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991.
992.
Bei Wen Longfei Li Yu Liu Hongna Zhang Xiaoyu Hu Xiao-quan Shan Shuzhen Zhang 《Plant and Soil》2013,362(1-2):345-354
Aims
There is a need to predict trace metal concentration in plant organs at given development stages. The aim of this work was to describe the Cd hyperaccumulation kinetics in the different plant organs, throughout the complete cultivation cycle, independently of a possible soil effect.Methods
Plants of Noccaea caerulescens were exposed in aeroponics to three constantly low Cd concentrations and harvested at 6 to 11 dates, until siliquae formation.Results
Dry matter allocation between roots and shoots was constant over time and exposure concentrations, as well as Cd allocation. However 86 % of the Cd taken up was allocated to the shoots. Senescent rosette leaves showed similar Cd concentrations to the living ones, suggesting no redistribution from old to young organs. The Cd root influx was proportional to the exposure concentration and constant over time, indicating that plant development had no effect on this. The bio-concentration factor (BCF), i.e. [Cd]plant/[Cd2+]solution for the whole plant, roots or shoots was independent of the exposure concentration and of the plant stage.Conclusions
Cadmium uptake in a given plant part could therefore be predicted at any plant stage by multiplying the plant part dry matter by the corresponding BCF and the Cd2+ concentration in the exposure solution. 相似文献993.
Yifu Yuan Weihua Guo Wenjuan Ding Ning Du Yujie Luo Jian Liu Fei Xu Renqing Wang 《Plant and Soil》2013,366(1-2):389-400
Background and aims
Anthropogenic nitrogen (N) and phosphorus (P) input has changed the relative importance of nutrient elements. This study aimed to examine the effects of different nutrient conditions on the interaction between exotic and native plants.Methods
We conducted a greenhouse experiment with a native species Quercus acutissima Carr. and an exotic species Rhus typhina L. grown in monocultures or mixtures, under three N:P ratios (5, 15 and 45 corresponding to N-limited, basic N and P supply and P-limited conditions, respectively). After 12 weeks of treatment, traits related to biomass allocation, leaf physiology and nutrient absorption were determined.Results
R. typhina was dominant under competition, with a high capacity for carbon assimilation and nutrient absorption, and the dominance was unaffected by increasing N:P ratios. R. typhina invested more photosynthate in leaves and more nutrients in the photosynthetic apparatus, enabling high biomass production. Q. acutissima invested more photosynthate in roots and more nutrients in leaf persistence at the expense of reduced carbon assimilation capacity.Conclusions
Different trade-offs in biomass and nutrient allocation of the two species is an important reason for their distinct performances under competition and helps R. typhina to maintain dominance under different nutrient conditions. 相似文献994.
Magnesium transporters and their role in Al tolerance in plants 总被引:2,自引:0,他引:2
Magnesium (Mg) is an essential macronutrient for plant growth, which has diverse biological functions. However, little is known about the transport system of this nutrient in plants. In the genome of plants such as rice and Arabidopsis, there are homologues of bacterial Mg transporters (CorA) and some of them have been functionally characterized, but the physiological role of these transporters are poorly understood. On the other hand, Mg is able to alleviate Al toxicity in a number of plant species, but the mechanisms underlying this alleviation are not well understood. Recently, this alleviation has been associated with a Mg transporter in rice. In this paper, we present our opinions on Mg transporters, which are required for uptake, translocation, distribution and storage in plants. Possible mechanisms for Mg-mediated alleviation of Al toxicity are also discussed. 相似文献
995.
Dynamics of fertilizer-derived organic nitrogen fractions in an arable soil during a growing season 总被引:8,自引:0,他引:8
Huijie Lü Hongbo He Jinsong Zhao Wei Zhang Hongtu Xie Guoqing Hu Xiao Liu Yeye Wu Xudong Zhang 《Plant and Soil》2013,373(1-2):595-607
Background
Inorganic fertilizer is one of the most important anthropogenic inputs which influences soil nutrient turnover in agricultural ecosystems. However, as the key process involved in the maintenance, transformation and stability of soil nitrogen (N), the incorporation and allocation of fertilizer N between different soil organic N (SON) fractions in a growing season remains largely unknown.Methods
In this study, a field experiment was conducted in triplicate of micro-plots and a total of 200 kg N ha?1 (15?N-labeled (NH4)2SO4, 98 atom %) was applied as a basal dressing and two top dressings, at jointing and filling stages, respectively, to a maize crop during one growing season. The distribution and seasonal dynamics of fertilizer N in different SON fractions (i.e., amino acids, amino sugars, hydrolyzable ammonium N and acid insoluble-N) were measured by liquid/gas chromatography–mass spectrometry (LC/GC-MS) and element analysis-combustion-isotope ratio mass spectrometry (EA-C-IRMS) techniques. Path analysis was used to evaluate the transformation processes between organic N fractions derived from fertilizer and N supply strategy in soil-plant system.Results
The accumulation of fertilizer-derived N in different organic fractions was season-specific. At jointing stage, preferential enrichment of 15?N was found in soil amino acids plus amino sugars, indicating the active biological immobilization of basal dressing fertilizer N. Nevertheless, there is still a small proportion of fertilizer N stabilized in the acid insoluble fraction. The accumulation of the residual fertilizer N in hydrolyzable ammonium N reached a maximum at filling stage and then declined significantly, implying the rapid release of the fertilizer N remained in mineral forms. The contents of amino acids changed slightly, but they played a very important role in mediating SON transformation.Conclusion
The hydrolyzable ammonium N was a temporary pool for rapid fertilizer N retention and simultaneously was apt to release N for crop uptake in the current season. In contrast, the amino acids could serve as a transitional pool of available N in the soil-crop system, while the acid insoluble fraction was as a stable pool of fertilizer N. Importantly, there is an interim shift among different pools to maintain soil N turnover; hence N in the amino acid fraction mediates N supply and the depolymerization of SON constituents controls the proceeding of fertilizer N cycling in the soil-plant system. 相似文献996.
Intermediate herbivory intensity of an aboveground pest promotes soil labile resources and microbial biomass via modifying rice growth 总被引:2,自引:0,他引:2
Jinghua Huang Manqiang Liu Xiaoyun Chen Jing Chen Fajun Chen Huixin Li Feng Hu 《Plant and Soil》2013,367(1-2):437-447
Background and Aims
The importance of aboveground herbivores for modifying belowground ecosystems has prompted numerous studies; however, studies can be biased by context dependent conditions which lead to extremely inconsistent results. So far, the impacts of herbivory intensity by important rice pests on rice paddy soil ecosystems are lacking. The aim of this study was to test the hypothesis that intermediate herbivory intensity of the brown planthopper (Nilaparvata lugens Stål) could promote soil labile resources and microbial biomass, while high intensity would show a reverse pattern, by mediating rice plant growth. This study will also help the development of integrative pest management.Methods
Four hopper infestation density treatments (0, 4, 8 and 12 nymphs per rice plant) and two infestation duration treatments (9 and 15 days after N. lugens infestation, DAI 9 and DAI 15) were established in a glasshouse experiment. Soil and plant were sampled destructively from four replicates and analysed for soil labile resources availability, soil microbial biomass and plant performance, respectively.Results
The infestation density significantly affected both shoot and root mass of rice (P?<?0.05), soil dissolved organic carbon (DOC) and nitrogen (DON), and microbial biomass carbon (MBC) and nitrogen (MBN), and the effects were further enhanced by prolonged infestation duration. Compared to the control (CK) without N. lugens, plant dry mass, DOC, DON, MBC and MBN increased under low (LD) and moderate hopper densities (MD) but decreased under high density (HD) on DAI 9. Moreover, the LD treatment exerted the most promotional effects on DAI 15. Rice root to shoot ratio generally increased in treatments subjected to herbivory. The labile resources and microbial biomass showed close relationships with both shoot and root mass across treatments, in particular with root mass on DAI 15. Such a trend indicated that the shift of photosynthate allocation to belowground contributed to changes of soil resource availability and microbial biomass.Conclusions
Intermediate herbivory intensity showed positive effects on rice seedling performance and, further, promoted soil labile resource availability and microbial biomass. The importance of extrapolating temporal and spatial scale, i.e. from the short-term greenhouse experiment to an entire rice growing season in the field, was highlighted. 相似文献997.
998.
999.
1000.
As protoplasts have the characteristics of no cell walls, rapid population growth, and synchronicity, they are useful tools for research in many fields, especially cellular biology (Table 1). This article is an overview that focuses on the application of protoplasts to investigate the mechanisms of dedifferentiation, including changes in hormone signals, epigenetic changes, and organelle distribution during the dedifferentiation process. The article also emphasizes the wide range of uses for protoplasts in studying protein positions and signaling during different stresses. The examples provided help to show that protoplast systems, for example the mesophyll protoplast system of Arabidopsis, represent promising tools for studying developmental biology. Meanwhile, specific analysis of protoplast, which comes from different tissue, has specific advantages and limitations (Table 2), and it can provide recommendations to use this system. 相似文献