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151.
In addition to assessing the impacts of CO2 doubling on environment and society, more consideration is needed to estimate extreme events or surprises. This is particularly important at the intersection of disciplines like climate and ecology because the potential for large discontinuities is high given all the possible climate/biota interactions. The vast disparities in scales encountered by those working in traditional ecology (typically 20 m) and climatology (typically 200 km) make diagnoses of such interactions difficult, but these can be addressed by an emerging research paradigm we call strategic cyclical scaling (SCS). The need to anticipate outlier events and assign them subjective probabilities suggests emphasis on interdisciplinary research associations. The desire to reduce societal vulnerability to such events suggests the need to build adaptive management and diverse economic activities into social organizations. The effectiveness of adaptation responses to anticipated climatic changes is complicated when consideration of transient changes, regional disturbances, large unforseeable natural fluctuations and surprises are considered. Slowing down the rate of disturbances and decreasing vulnerability are advocated as the most prudent responses to the prospect of human-induced climatic changes. 相似文献
152.
153.
Summary Sequence-specific 1H and 15N resonance assignments have been made for 137 of the 146 nonprolyl residues in oxidized Desulfovibrio desulfuricans [Essex 6] flavodoxin. Assignments were obtained by a concerted analysis of the heteronuclear three-dimensional 1H-15N NOESY-HMQC and TOCSY-HMQC data sets, recorded on uniformly 15N-enriched protein at 300 K. Numerous side-chain resonances have been partially or fully assigned. Residues with overlapping 1HN chemical shifts were resolved by a three-dimensional 1H-15N HMQC-NOESY-HMQC spectrum. Medium-and long-range NOEs, 3JNH
coupling constants, and 1HN exchange data indicate a secondary structure consisting of five parallel -strands and four -helices with a topology similar to that of Desulfovibrio vulgaris [Hidenborough] flavodoxin. Prolines at positions 106 and 134, which are not conserved in D. vulgaris flavodoxin, contort the two C-terminal -helices.Abbreviations CSI
chemical shift index
- DQF-COSY
double-quantum-filtered correlation spectroscopy
- DIPSI
decoupling in the presence of scalar interactions
- FMN
flavin mononucleotide
- GARP
globally optimized alternating phase rectangular pulse
- HMQC
heteronuclear multiple-quantum coherence
- HSQC
heteronuclear single-quantum coherence
- NOE
nuclear Overhauser effect
- NOESY
nuclear Overhauser enhancement spectroscopy
- TOCSY
total correlation spectroscopy
- TPPI
time-proportional phase increments
- TSP
3-(trimethylsilyl)propionic-2,2,3,3-d
4 acid, sodium salt 相似文献
154.
Bruce Aylward Katie Allen Jaime Echeverría Joseph Tosi 《Biodiversity and Conservation》1996,5(3):315-343
The paper discusses the sustainability of the Monteverde Cloud Forest Preserve in the context of Costa Rican ecotourism. While the history of the Preserve is somewhat unique, the analysis of visitation, financial, ecological and economic factors provides a convincing case that tourism at the Preserve is sustainable. The experience of the Preserve is also put in the context of Costa Rican ecotourism, particularly to the national parks. The paper concludes that the Preserve has played a very important role in the development of Costa Rica as an ecotourism destination. Nonetheless, the failure of experience at the Preserve to inform recent changes in national park pricing policy reveal that Costa Rica has yet to fully capitalize on the experience gained and lessons learned at the Preserve. 相似文献
155.
贺兰山不同生境旱生灌木的解剖学研究 总被引:9,自引:1,他引:8
贺兰山荒漠地带三种不同基质生境的20种旱生灌木的营养器官的比较解剖学研究表明:其共同特点是叶片的表面积/体积的比值小,叶表具厚的角质层、表皮毛,气孔下陷、并具孔下室,叶向中栅栏组织发达;轴器官中木栓层细胞层数多,皮层较厚,机械组织发达,木薄壁组织及髓部细胞的细胞壁术化加厚,根内都具周皮、木质部的导管分子大小不一、频率较高。此外,根、茎、叶中普遍存在粘液细胞和草酸钙结晶,部分植物的根和茎内有异常维管组织。这些结构特征都与早生环境相关,而不同基质生境中生长的植物尚存在一定差异。 相似文献
156.
研究了水平沟耕作条件下密度、施肥对谷子产量的影响,寻找最佳施肥和密度以获得最高产量和纯收入,并对株高、叶面积、叶面积系数、蒸腾强度、耗水量等指标作了研究,认为水平沟耕作有良好的经济和生态效益。 相似文献
157.
生态文明——人类未来的文明:关于人与自然持续发展的思考 总被引:3,自引:1,他引:2
生态文明人类未来的文明关于人与自然持续发展的思考李建国(中国林业科学研究院林业研究所,北京100091)EcologicalCivilizationtheHumanFutureCivilizationConsiderationaboutHumanbe... 相似文献
158.
Atmospheric carbon dioxide enrichment and increasing nitrogen deposition are often predicted to increase forest productivity based on currently available data for isolated forest tree seedlings or their leaves. However, it is highly uncertain whether such seedling responses will scale to the stand level. Therefore, we studied the effects of increasing CO2 (280, 420 and 560 μL L-1) and increasing rates of wet N deposition (0, 30 and 90 kg ha-1 y-1) on whole stands of 4-year-old spruce trees (Picea abies). One tree from each of six clones, together with two herbaceous understory species, were established in each of nine 0.7 m2 model ecosystems in nutrient poor forest soil and grown in a simulated montane climate for two years. Shoot level light-saturated net photosynthesis measured at growth CO2 concentrations increased with increasing CO2, as well as with increasing N deposition. However, predawn shoot respiration was unaffected by treatments. When measured at a common CO2 concentration of 420 μL L-1 37% down-regulation of photosynthesis was observed in plants grown at 560 μL CO2 L-1. Length growth of shoots and stem diameter were not affected by CO2 or N deposition. Bud burst was delayed, leaf area index (LAI) was lower, needle litter fall increased and soil CO2 efflux increased with increasing CO2. N deposition had no effect on these traits. At the ecosystem level the rate of net CO2 exchange was not significantly different between CO2 and N treatments. Most of the responses to CO2 studied here were nonlinear with the most significant differences between 280 and 420 μL CO2 L-1 and relatively small changes between 420 and 560 μL CO2 L-1. Our results suggest that the lack of above-ground growth responses to elevated CO2 is due to the combined effects of physiological down-regulation of photosynthesis at the leaf level, allometric adjustment at the canopy level (reduced LAI), and increasing strength of below-ground carbon sinks. The non-linearity of treatment effects further suggests that major responses of coniferous forests to atmospheric CO2 enrichment might already be under way and that future responses may be comparatively smaller. 相似文献
159.
旱地玉米农田棵间蒸发研究 总被引:3,自引:0,他引:3
采用中子微区模拟装置测量旱地玉农田棵间蒸发,实验表明,本实验装置实用可行。晋西棵间蒸发量占降水量(510nm)的55%以上,棵间蒸发与蒸散的比值同时叶面积指数呈反相关,玉米产量与作物蒸腾呈正相关。 相似文献
160.
Colleen K. Kelly 《植被学杂志》1996,7(3):417-424
Abstract. In an effort to identify ‘plant functional types’, the islands floras of Great Britain and Kríti (Crete, Greece) were examined separately for ecological correlates of plant range size. Plant functional types (PFTs) were defined here as categories into which plants could be grouped on the basis of attributes that predict greater or lesser sensitivity to ecological variability. Plant range size indicates commonness of a species and was assumed to be a proxy for ‘ecological flexibility’, i.e. species of larger range sizes can better withstand environmental change and differences than species of smaller range sizes. Using evolutionary comparative methods that account for the effect of taxonomic relatedness, both floras were investigated for the effects on range size of woodiness vs. non-woodiness, trees vs. shrubs, trees vs. herbs and shrubs vs. herbs. The British flora was examined additionally for the effects of wind- vs. non-wind-pollination, self vs. animal pollination and animal vs. non-animal fruit dispersal on range size. Two analyses showed significant effects on range size: for British species, trees had larger ranges than shrubs, and wind- pollinated species had larger ranges than non-wind-pollinated species. It is suggested that the lack of a similar pattern for shrubs and trees in Kríti is because the lower water availability of Kríti imbues shrubs with an ecophysiological advantage not relevant in plants of Great Britain. That trees have larger range sizes than shrubs in Great Britain is ascribed to the greater importance of competition for light when other factors are not at issue. The greater range of wind-pollinated than non-windpollinated species in Great Britain is postulated to be because both mutualists must be capable of invading new areas. This may be termed a ‘cost of mutualism’. In terms of PFTs, the results indicate that ‘life-form’ is too broad a classification category by which to differentiate relative sensitivity to environmental variability in Great Britain, in that there were significant differences in range size of trees and shrubs, but not between either of the two categories and herbs, or between woody and non-woody plants. Although pollination type may predict relative sensitivity to variation in Great Britain, dispersal type will not. Finally, differences between Great Britain and Kríti in relative range size patterns suggests that plant functional types may be specific to a region or set of conditions. 相似文献