Creat membership Creat membership
Sign in

Forgot password?

  • Forgot password?
    Sign Up
  • Confirm
    Sign In
home > search

Now showing items 1 - 16 of 32


    Provided in the invention is a thin notebook computer mechanical keyboard. The keyboard comprises: a reinforcement iron plate, a scissor foot, a keycap, a base, a pressing stopper, a spring and a cover. The reinforcement iron plate is arranged on a circuit board and provided with a hollow groove and a plurality of clamping parts at corners thereof. The scissor foot is provided with a plurality of first positioning parts and a plurality of second positioning parts. The first positioning parts are vertically and movably clamped on the clamping parts, and the scissor foot is hollow. The keycap is provided with a plurality of fastening parts. The fastening parts are fastened on the second positioning parts. When the keycap is pressed to a certain extent, an action between a hand touch and a fourth terminal produces a sound of an upward impact against the cover. Moreover, when the keycap is pressed, the scissor foot maintains the balance of the whole keycap without catching the keycap, ensuring a favorable touch feeling; a switch is directly installed on a PCB and passes through the reinforcement iron plate; thus, the scissor foot structure maintains the balance of the keycap, and balanced movement is achieved without falling short of thinning requirements.
    Download Collect
  • Isotopic evidence for oligotrophication of terrestrial ecosystems.

    Craine, Joseph M   Elmore, Andrew J   Wang, Lixin   Aranibar, Julieta   Bauters, Marijn   Boeckx, Pascal   Crowley, Brooke E   Dawes, Melissa A   Delzon, Sylvain   Fajardo, Alex   Fang, Yunting   Fujiyoshi, Lei   Gray, Alan   Guerrieri, Rossella   Gundale, Michael J   Hawke, David J   Hietz, Peter   Jonard, Mathieu   Kearsley, Elizabeth   Kenzo, Tanaka   Makarov, Mikhail   Maranon-Jimenez, Sara   McGlynn, Terrence P   McNeil, Brenden E   Mosher, Stella G   Nelson, David M   Peri, Pablo L   Roggy, Jean Christophe   Sanders-DeMott, Rebecca   Song, Minghua   Szpak, Paul   Templer, Pamela H   Van der Colff, Dewidine   Werner, Christiane   Xu, Xingliang   Yang, Yang   Yu, Guirui   Zmudczynska-Skarbek, Katarzyna  

    Human societies depend on an Earth system that operates within a constrained range of nutrient availability, yet the recent trajectory of terrestrial nitrogen (N) availability is uncertain. Examining patterns of foliar N concentrations and isotope ratios (delta15N) from more than 43,000 samples acquired over 37years, here we show that foliar N concentration declined by 9% and foliar delta15N declined by 0.6-1.6. Examining patterns across different climate spaces, foliar delta15N declined across the entire range of mean annual temperature and mean annual precipitation tested. These results suggest declines in N supply relative to plant demand at the global scale. In all, there are now multiple lines of evidence of declining N availability in many unfertilized terrestrial ecosystems, including declines in delta15N of tree rings and leaves from herbarium samples over the past 75-150years. These patterns are consistent with the proposed consequences of elevated atmospheric carbon dioxide and longer growing seasons. These declines will limit future terrestrial carbon uptake and increase nutritional stress for herbivores.=20
    Download Collect
  • Land Use and Land Cover Change in the Kailash Sacred Landscape of China

    Duan, Cheng   Shi, Peili   Song, Minghua   Zhang, Xianzhou   Zong, Ning   Zhou, Caiping  

    Land use and land cover change (LUCC) is an important driver of ecosystem function and services. Thus, LUCC analysis may lay foundation for landscape planning, conservation and management. It is especially true for alpine landscapes, which are more susceptible to climate changes and human activities. However, the information on LUCC in sacred landscape is limited, which will hinder the landscape conservation and development. We chose Kailash Sacred Landscape in China (KSL-China) to investigate the patterns and dynamics of LUCC and the driving forces using remote sensing data and meteorological data from 1990 to 2008. A supervised classification of land use and land cover was established based on field survey. Rangelands presented marked fluctuations due to climatic warming and its induced drought, for example, dramatic decreases were found in high- and medium-cover rangelands over the period 2000-2008. And recession of most glaciers was also observed in the study period. Instead, an increase of anthropogenic activities accelerated intensive alteration of land use, such as conversion of cropland to built-up land. We found that the change of vegetation cover was positively correlated with growing season precipitation (GSP). In addition, vegetation cover was substantially reduced along the pilgrimage routes particularly within 5 km of the routes. The findings of the study suggest that climatic warming and human disturbance are interacted to cause remarkable LUCC. Tourism development was responsible land use change in urban and pilgrimage routes. This study has important implications for landscape conservation and ecosystem management. The reduction of rangeland cover may decrease the rangeland quality and pose pressure for the carrying capacity of rangelands in the KSL-China. With the increasing risk of climate warming, rangeland conservation is imperative. The future development should shift from livestock-focus animal husbandry to service-based ecotourism in the sacred landscape.
    Download Collect
  • Nitrogen Critical Loads for an Alpine Meadow Ecosystem on the Tibetan Plateau

    Zong, Ning   Shi, Peili   Song, Minghua   Zhang, Xianzhou   Jiang, Jing   Chai, Xi  

    Increasing atmospheric nitrogen (N) deposition has the potential to alter plant diversity and thus the function and stability of terrestrial ecosystems. N-limited alpine ecosystems are expected to be particularly susceptible to increasing N deposition. However, little is known about the critical loads and saturation thresholds of ecosystem responses to increasing N deposition on the Tibetan Plateau, despite its importance to ecosystem management. To evaluate the N critical loads and N saturation thresholds in an alpine ecosystem, in 2010, we treated an alpine meadow with five levels of N addition (0, 10, 20, 40, and 80 kg N ha(-1) year(-1)) and characterized plant and soil responses. The results showed that plant species richness and diversity index did not statistically vary with N addition treatments, but they both changed with years. N addition affected plant cover and aboveground productivity, especially for grasses, and soil chemical features. The N critical loads and saturation thresholds, in terms of plant cover and biomass change at the community level, were 8.8-12.7 and 50 kg N ha(-1) year(-1) (including the ambient N deposition rate), respectively. However, pronounced changes in soil inorganic N and net N mineralization occurred under the 20 and 40 kg N ha(-1) year(-1) treatments. Our results indicate that plant community cover and biomass are more sensitive than soil to increasing N inputs. The plant community composition in alpine ecosystems on the Qinghai-Tibetan Plateau may change under increasing N deposition in the future.
    Download Collect
  • Effects of aggressive traits on cyberbullying:Mediated moderation or moderated mediation?

    Song, Minghua   Zhu, Zhuan   Liu, Shen   Fan, Hang   Zhu, Tingting   Zhang, Lin  

    To explore the process of cyberbullying, the current study investigated the relationships among aggressive traits, beliefs about aggression, network public opinion, and cyberbullying. A questionnaire survey was conducted among 693 Chinese college students. Based on the findings, we constructed two competing models (mediated moderation and moderated mediation). The results revealed the following: (1) Aggressive traits and beliefs about aggression were all positively correlated with cyberbullying, aggressive traits were positively correlated with beliefs about aggression, and aggressive traits were negatively correlated with network public opinion. (2) The effect of aggressive traits on beliefs about aggression and cyberbullying was moderated by network public opinion. When network public opinion included irrational comments, aggressive traits directly and indirectly affected cyberbullying. When network public opinion included rational comments, aggressive traits only directly affected cyberbullying. Finally, (3) the effect of aggressive traits on cyberbullying was moderated by network public opinion and the moderating effect of network public opinion was partly realized through the mediating effect of beliefs about aggression. The findings contribute to our understanding of when and how aggressive traits affect cyberbullying. We found support for the mediated moderation model, and the results have implications for prevention and intervention in cyberbullying.
    Download Collect
  • Interactions between intercropped Avena sativa and Agropyron cristatum for nitrogen uptake

    Liu, Min   Li, Huimin   Song, Jingjing   Song, Minghua   Qiao, Na   Tian, Yuqiang   Liu, Yanjie   Niu, Haishan  

    Aims The effect of cropping regime on nitrogen (N) uptake in two coexisting plant grass species (Avena sativa and Agropyron cristatum) was investigated. Methods The two grass species were cultivated by monocropping or intercropping. N-15-labeling was used to examine N uptake of NH4+ versus NO3- at 0-5 cm and 5-15 cm soil depths. Results The aboveground and total biomass of intercropped A. sativa was 1.3 times greater than monocropped A. sativa. The biomass of A. cristatum did not change between cropping systems. In the 0-5 cm soil layer, uptake of NO3- by A. sativa was 0.5 times less in the intercropped system than in the monocropped system, whereas uptake of NO3- by A. cristatum was 2.0 times more in the intercropped system. In the 5-15 cm depth, intercropping did not change N uptake by A. sativa but decreased NO3- uptake to 0.6 times by A. cristatum. Conclusions Complementarity in N uptake between A. sativa and A. cristatum in the upper 0-5 cm soil layer is conducive to biomass accumulation. Intercropped A. sativa and A. cristatum does not compete strongly for soil resources and can alter their N uptake patterns to optimize biomass production.
    Download Collect
  • Effects of aggressive traits on cyberbullying: Mediated moderation or moderated mediation?

    Song, Minghua   Zhu, Zhuan   Liu, Shen   Fan, Hang   Zhu, Tingting   Zhang, Lin  

    Download Collect
  • Seasonal patterns of root and shoot interactions in an alpine meadow on the Tibetan Plateau

    Song, Minghua   Hu, Qiwu   Tian, Yuqiang   Ouyang, Hua  

    Numerous studies have showed that the balance between negative and positive plant-plant interactions shifted along environmental gradients. But little is known how the positive or negative plant-plant interactions varied with temporal fluctuating habitat conditions and plant ontogenetic phases. In a 2-year experiment, the four perennial grasses (Kobresia humilis, Stipa aliena, Elymus nutans and Saussurea superba) were grown under four interaction treatments (no root or shoot interaction, only shoot interaction, only root interaction, root and shoot interaction). Intensity of above- and belowground interactions is proposed to vary with the fluctuation of seasonal climatic conditions and soil available nutrients. Here we report measurements of above- and belowground interactions during entire growing season. Correlation between plant interaction intensity and seasonal soil available N as well as habitat climate conditions was also performed. Our experiment found that root interactions had negative effect on plant growth for the four species during growing season. However, both negative and positive shoot interactions occurred among the four species. Despite there being shoot facilitative effect for E. nutans and S. superba, the full interaction was negative, suggested that root interaction take more important role on plant growth than that of shoot interaction. The interaction between root and shoot effect varied as a function of species identity and growth phases. The weak correlation of plant interaction intensity to habitat environmental factors suggested that plant ontogenetic characteristics may be primary factors causing temporal variation in plant interaction.
    Download Collect
  • Feeding solution:Crop-livestock integration via crop-forage rotation in the southern Tibetan Plateau

    Duan, Cheng   Zong, Ning   Wang, Jingsheng   Song, Minghua   Zhang, Xianzhou  

    Separated, specialized crop and forage production has a long history on the Tibetan Plateau. Such isolated pattern has led to current concerns of intensified agriculture, environmental degradation and forage shortage in the increasing pressures of population and livestock growth. To tackle the predicament of feed shortage, an alternative to specialized agriculture is crop-forage rotation for potential crop-livestock integration (CLI). However, its feasibility is understudied and the potential remains unanswered in the southern Tibetan Plateau. Based on the analyses of grazing pressure index and growing degree days (GDD), we examined the practicability and modes of crop-forage rotation for feed solution in the middle reaches of the Yarlung Tsangpo Watershed (YTW). Additionally, cultivated land area suitable for forage rotation after crop harvest was defined. Livestock carrying capacity and grazing pressure indices under forage rotation were compared with those only with rangeland and crop residues. We found that the average number of livestock maintained about 9 million standard sheep unit (SU) in the period 2000-2015, which exceeded the carrying capacity provided by rangeland and crop residues. Growing season length are about 200 days ranging from late April to early November, with daily average temperature >=3D 5 degrees C and over 1500 GDD in the Yarlung Tsangpo River valley. About 158,377 ha, accounting for 74.4% of the cultivated land is suitable for annual forage rotation after crop harvest. The appropriate period for annual forage rotation is ca. 80 days, i.e. from 20th August to 8th November after spring crop harvest and from 1st August to 20th October after winter crop harvest. In addition, the information of GDD also provides elevational thresholds for implementing forage rotation practice in the future. The upper limits for forage rotation are 4000 m after spring crop harvest and 4500 m after winter crop harvest. The grazing pressure indices in most counties can be substantially reduced after filling feed gaps through crop-forage rotation. We demonstrate that crop-forage rotation could be a good solution to forage deficits. These findings also provide insights into promising potential for crop-livestock integration to alleviate grazing pressure in the southern Tibetan agricultural area. However, adoption will depend on farmers' preference and market factors. Further efforts are needed to encourage farmers' involvement into the forage rotation by policy guidance.
    Download Collect
  • Clonal plants and plant species diversity in wetland ecosystems in China

    Song, Minghua   Dong, Ming  

    Download Collect
  • Nutrient limitation of alpine plants: Implications from leaf N : P stoichiometry and leaf delta N-15

    Wanek, Wolfgang   Zhou, Caiping   Richter, Andreas   Song, Minghua   Cao, Guangmin   Ouyang, Hua   Kuzyakov, Yakov  

    Nitrogen (N) deposition can affect grassland ecosystems by altering biomass production, plant species composition and abundance. Therefore, a better understanding of the response of dominant plant species to N input is a prerequisite for accurate prediction of future changes and interactions within plant communities. We evaluated the response of seven dominant plant species on the Tibetan Plateau to N input at two levels: individual species and plant functional group. This was achieved by assessing leaf N : P stoichiometry, leaf delta N-15 and biomass production for the plant functional groups. Seven dominant plant species-three legumes, two forbs, one grass, one sedge-were analyzed for N, P, and delta N-15 2 years after fertilization with one of the three N forms: NO3-, NH4+, or NH4NO3 at four application rates (0, 7.5, 30, and 150 kg N ha(-1) y(-1)). On the basis of biomass production and leaf N : P ratios, we concluded that grasses were limited by available N or co-limited by available P. Unlike for grasses, leaf N : P and biomass production were not suitable indicators of N limitation for legumes and forbs in alpine meadows. The poor performance of legumes under high N fertilization was mainly due to strong competition with grasses. The total above-ground biomass was not increased by N fertilization. However, species composition shifted to more productive grasses. A significant negative correlation between leaf N : P and leaf delta N-15 indicated that the two forbs Gentiana straminea and Saussurea superba switched from N deficiency to P limitation (e. g., N excess) due to N fertilization. These findings imply that alpine meadows will be more dominated by grasses under increased atmospheric N deposition.
    Download Collect
  • Three Tibetan grassland plant species tend to partition niches with limited plasticity in nitrogen use

    Zhang, Li   Pang, Rui   Xu, Xingliang   Song, Minghua   Li, Yikang   Zhou, Huakun   Cui, Xiaoyong   Wang, Yanfen   Ouyang, Hua  

    Aims Niche complementarity theory explains how species coexist by using different resources. Two pathways to partition resource have been demonstrated: classical niche differentiation and plasticity in resource use. We aimed to determine N-uptake patterns in three Tibetan Plateau grassland species, and to examine how N-partitioning is driven by neighbor interactions. Methods We conducted a transplantation experiment using ten plant communities, each comprising a different combination of Kobresia humilis, Stipa aliena, and Saussurea superba. Soil was sprayed uniformly with a mixture of (NH4)(2)SO4, KNO3, and glycine (C2H5NO2) (1:1:1 by mass of N, each containing one form of N-15) after growing for 45 days. Results Across three species, the N-uptake pattern was NO3- > NH4+ > glycine (NO3-: 58.47%; NH4+: 26.91%; glycine: 14.62%). Neighbor presence had species-specific effects on N-15 recovery. Kobresia humilis took up more N-15-NO3- when it was in competition with other species, whereas Stipa aliena and Saussurea superba took up more N-15-NH4+ and N-15-glycine, respectively. Conclusions Plasticity in N resource utilization of the three species was limited. The species competed for N resources proportionally to the availability of these sources, and tended to partition niches. These findings provide important insights into how plant species grow together in alpine grasslands.
    Download Collect
  • Clonality-climate relationships along latitudinal gradient across China: adaptation of clonality to environments.

    Ye, Duo   Hu, Yukun   Song, Minghua   Pan, Xu   Xie, Xiufang   Liu, Guofang   Ye, Xuehua   Dong, Ming  

    Plant clonality, the ability of a plant species to reproduce itself vegetatively through ramets (shoot-root units), occurs in many plant species and is considered to be more frequent in cold or wet environments. However, a deeper understanding on the clonality-climate relationships along large geographic gradients is still scarce. In this study we revealed the clonality-climate relationships along latitudinal gradient of entire China spanning from tropics to temperate zones using clonality data for 4015 vascular plant species in 545 terrestrial communities. Structural equation modeling (SEM) showed that, in general, the preponderance of clonality increased along the latitudinal gradient towards cold, dry or very wet environments. However, the distribution of clonality in China was significantly but only weakly correlated with latitude and four climatic factors (mean annual temperature, temperature seasonality, mean annual precipitation, precipitation seasonality). Clonality of woody and herbaceous species had opposite responses to climatic variables. More precisely, woody clonality showed higher frequency in wet or climatically stable environments, while herbaceous clonality preferred cold, dry or climatically instable environments. Unexplained variation in clonality may be owed to the influences of other environmental conditions and to different clonal strategies and underlying traits adopted by different growth forms and phylogenetic lineages. Therefore, in-depth research in terms of more detailed clonal growth form, phylogeny and additional environmental variables are encouraged to further understand plant clonality response to climatic and/or edaphic conditions. =20
    Download Collect
  • Patterns in leaf traits of leguminous and non-leguminous dominant trees along a rainfall gradient in Ghana

    Song, Minghua   Djagbletey, Gloria   Nkrumah, Elvis E.   Huang, Mei  

    Aims Both dominance distribution of species and the composition of the dominant species determine the distribution of traits within community. Leaf carbon (C) and nitrogen (N) isotopic composition are important leaf traits, and such traits of dominant species are associated with ecosystem C, water and N cycling. Very little is known how dominant species with distinct traits (e.g. N-fixing leguminous and non-leguminous trees) mediate resource utilization of the ecosystems in stressful environment. Methods Leaves of 81 dominant leguminous and non-leguminous trees were collected in forest (moist semi-deciduous and dry semi-deciduous ecosystems) and savanna (costal savanna, Guinean savanna and west Sudanian savanna ecosystems) areas and the transitional zone (between the forest and the savanna) along the transect from the south to the north of Ghana. We measured leaf traits, i.e. leaf delta C-13, leaf delta N-15, leaf water content, leaf mass per area (LMA) and C and N concentration. Correlation analyses were used to examine trait-trait relationships, and relationships of leaf traits with temperature and precipitation. We used analysis of covariance to test the differences in slopes of the linear regressions between legumes and non-legumes. Important Findings Leaf delta C-13, delta N-15, leaf water content and LMA did not differ between leguminous and non-leguminous trees. Leaf N concentration and C: N ratio differed between the two groups. Moreover, leaf traits varied significantly among the six ecosystems. delta C-13 values were negatively correlated with annual precipitation and positively correlated with mean annual temperature. In contrast, leaf delta N-15 of non-leguminous trees were positively correlated with annual precipitation and negatively correlated with mean annual temperature. For leguminous trees, such correlations were not significant. We also found significant coordination between leaf traits. However, the slopes of the linear relationships were significantly different between leguminous and non-leguminous trees. Our results indicate that shifts in dominant trees with distinct water-use efficiency were corresponded to the rainfall gradient. Moreover, leguminous trees, those characterized with relative high water-use efficiency in the low rainfall ecosystems, were also corresponded to the relative high N use efficiency. The high proportion of leguminous trees in the savannas is crucial to mitigate nutrient stress.
    Download Collect
  • Distributions of Dominant Tree Species on the Tibetan Plateau under Current and Future Climate Scenarios

    Song, Minghua   Zhou, Caiping   Ouyang, Hua  

    Download Collect
  • Mean-field analysis of two-species totally asymmetric simple exclusion process (TASEP) with attachment and detachment

    Song, Minghua   Zhang, Yunxin  

    Download Collect
1 2


If you have any feedback, Please follow the official account to submit feedback.

Turn on your phone and scan

Submit Feedback