全文获取类型
收费全文 | 1362篇 |
免费 | 66篇 |
国内免费 | 1篇 |
专业分类
林业 | 129篇 |
农学 | 49篇 |
基础科学 | 5篇 |
219篇 | |
综合类 | 74篇 |
农作物 | 33篇 |
水产渔业 | 102篇 |
畜牧兽医 | 652篇 |
园艺 | 46篇 |
植物保护 | 120篇 |
出版年
2022年 | 12篇 |
2021年 | 19篇 |
2020年 | 19篇 |
2019年 | 14篇 |
2018年 | 45篇 |
2017年 | 44篇 |
2016年 | 50篇 |
2015年 | 26篇 |
2014年 | 38篇 |
2013年 | 55篇 |
2012年 | 83篇 |
2011年 | 67篇 |
2010年 | 44篇 |
2009年 | 47篇 |
2008年 | 55篇 |
2007年 | 64篇 |
2006年 | 61篇 |
2005年 | 67篇 |
2004年 | 53篇 |
2003年 | 50篇 |
2002年 | 46篇 |
2001年 | 41篇 |
2000年 | 35篇 |
1999年 | 41篇 |
1997年 | 9篇 |
1996年 | 10篇 |
1992年 | 16篇 |
1991年 | 12篇 |
1990年 | 19篇 |
1989年 | 13篇 |
1988年 | 19篇 |
1987年 | 17篇 |
1986年 | 16篇 |
1985年 | 10篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1978年 | 14篇 |
1977年 | 7篇 |
1976年 | 8篇 |
1974年 | 9篇 |
1973年 | 9篇 |
1972年 | 8篇 |
1971年 | 14篇 |
1970年 | 10篇 |
1968年 | 11篇 |
1966年 | 8篇 |
1914年 | 7篇 |
排序方式: 共有1429条查询结果,搜索用时 31 毫秒
111.
A map of the interactome network of the metazoan C. elegans 总被引:1,自引:0,他引:1
Li S Armstrong CM Bertin N Ge H Milstein S Boxem M Vidalain PO Han JD Chesneau A Hao T Goldberg DS Li N Martinez M Rual JF Lamesch P Xu L Tewari M Wong SL Zhang LV Berriz GF Jacotot L Vaglio P Reboul J Hirozane-Kishikawa T Li Q Gabel HW Elewa A Baumgartner B Rose DJ Yu H Bosak S Sequerra R Fraser A Mango SE Saxton WM Strome S Van Den Heuvel S Piano F Vandenhaute J Sardet C Gerstein M Doucette-Stamm L Gunsalus KC Harper JW Cusick ME Roth FP Hill DE Vidal M 《Science (New York, N.Y.)》2004,303(5657):540-543
To initiate studies on how protein-protein interaction (or "interactome") networks relate to multicellular functions, we have mapped a large fraction of the Caenorhabditis elegans interactome network. Starting with a subset of metazoan-specific proteins, more than 4000 interactions were identified from high-throughput, yeast two-hybrid (HT=Y2H) screens. Independent coaffinity purification assays experimentally validated the overall quality of this Y2H data set. Together with already described Y2H interactions and interologs predicted in silico, the current version of the Worm Interactome (WI5) map contains approximately 5500 interactions. Topological and biological features of this interactome network, as well as its integration with phenome and transcriptome data sets, lead to numerous biological hypotheses. 相似文献
112.
113.
Michel E Baglin A Auvergne M Catala C Samadi R Baudin F Appourchaux T Barban C Weiss WW Berthomieu G Boumier P Dupret MA Garcia RA Fridlund M Garrido R Goupil MJ Kjeldsen H Lebreton Y Mosser B Grotsch-Noels A Janot-Pacheco E Provost J Roxburgh IW Thoul A Toutain T Tiphène D Turck-Chieze S Vauclair SD Vauclair GP Aerts C Alecian G Ballot J Charpinet S Hubert AM Lignières F Mathias P Monteiro MJ Neiner C Poretti E de Medeiros JR Ribas I Rieutord ML Cortés TR Zwintz K 《Science (New York, N.Y.)》2008,322(5901):558-560
Oscillations of the Sun have been used to understand its interior structure. The extension of similar studies to more distant stars has raised many difficulties despite the strong efforts of the international community over the past decades. The CoRoT (Convection Rotation and Planetary Transits) satellite, launched in December 2006, has now measured oscillations and the stellar granulation signature in three main sequence stars that are noticeably hotter than the sun. The oscillation amplitudes are about 1.5 times as large as those in the Sun; the stellar granulation is up to three times as high. The stellar amplitudes are about 25% below the theoretic values, providing a measurement of the nonadiabaticity of the process ruling the oscillations in the outer layers of the stars. 相似文献
114.
Burgert R Schnöckel H Grubisic A Li X Stokes ST Bowen KH Ganteför GF Kiran B Jena P 《Science (New York, N.Y.)》2008,319(5862):438-442
The reactivity pattern of small (approximately 10 to 20 atoms) anionic aluminum clusters with oxygen has posed a long-standing puzzle. Those clusters with an odd number of atoms tend to react much more slowly than their even-numbered counterparts. We used Fourier transform ion cyclotron resonance mass spectrometry to show that spin conservation straightforwardly accounts for this trend. The reaction rate of odd-numbered clusters increased appreciably when singlet oxygen was used in place of ground-state (triplet) oxygen. Conversely, monohydride clusters AlnH-, in which addition of the hydrogen atom shifts the spin state by converting formerly open-shell structures to closed-shell ones (and vice versa), exhibited an opposing trend: The odd-n hydride clusters reacted more rapidly with triplet oxygen. These findings are supported by theoretical simulations and highlight the general importance of spin selection rules in mediating cluster reactivity. 相似文献
115.
The human cofactor complexes ARC (activator-recruited cofactor) and CRSP (cofactor required for Sp1 activation) mediate activator-dependent transcription in vitro. Although these complexes share several common subunits, their structural and functional relationships remain unknown. Here, we report that affinity-purified ARC consists of two distinct multisubunit complexes: a larger complex, denoted ARC-L, and a smaller coactivator, CRSP. Reconstituted in vitro transcription with biochemically separated ARC-L and CRSP reveals differential cofactor functions. The ARC-L complex is transcriptionally inactive, whereas the CRSP complex is highly active. Structural determination by electron microscopy (EM) and three-dimensional reconstruction indicate substantial differences in size and shape between ARC-L and CRSP. Moreover, EM analysis of independently derived CRSP complexes reveals distinct conformations induced by different activators. These results suggest that CRSP may potentiate transcription via specific activator-induced conformational changes. 相似文献
116.
Spahni R Chappellaz J Stocker TF Loulergue L Hausammann G Kawamura K Flückiger J Schwander J Raynaud D Masson-Delmotte V Jouzel J 《Science (New York, N.Y.)》2005,310(5752):1317-1321
The European Project for Ice Coring in Antarctica Dome C ice core enables us to extend existing records of atmospheric methane (CH4) and nitrous oxide (N2O) back to 650,000 years before the present. A combined record of CH4 measured along the Dome C and the Vostok ice cores demonstrates, within the resolution of our measurements, that preindustrial concentrations over Antarctica have not exceeded 773 +/- 15 ppbv (parts per billion by volume) during the past 650,000 years. Before 420,000 years ago, when interglacials were cooler, maximum CH4 concentrations were only about 600 ppbv, similar to lower Holocene values. In contrast, the N2O record shows maximum concentrations of 278 +/- 7 ppbv, slightly higher than early Holocene values. 相似文献
117.
Polyansky OL Császár AG Shirin SV Zobov NF Barletta P Tennyson J Schwenke DW Knowles PJ 《Science (New York, N.Y.)》2003,299(5606):539-542
The spectrum of water vapor is of fundamental importance for a variety of processes, including the absorption and retention of sunlight in Earth's atmosphere. Therefore, there has long been an urgent need for a robust and accurate predictive model for this spectrum. In our work on the high-resolution spectrum of water, we report first-principles calculations that approach experimental accuracy. To achieve this, we performed exceptionally large electronic structure calculations and considered a variety of effects, including quantum electrodynamics, which have routinely been neglected in studies of small many-electron molecules. The high accuracy of the resulting ab initio procedure is demonstrated for the main isotopomers of water. 相似文献
118.
Increasing river discharge to the Arctic Ocean 总被引:10,自引:0,他引:10
Peterson BJ Holmes RM McClelland JW Vörösmarty CJ Lammers RB Shiklomanov AI Shiklomanov IA Rahmstorf S 《Science (New York, N.Y.)》2002,298(5601):2171-2173
Synthesis of river-monitoring data reveals that the average annual discharge of fresh water from the six largest Eurasian rivers to the Arctic Ocean increased by 7% from 1936 to 1999. The average annual rate of increase was 2.0 +/- 0.7 cubic kilometers per year. Consequently, average annual discharge from the six rivers is now about 128 cubic kilometers per year greater than it was when routine measurements of discharge began. Discharge was correlated with changes in both the North Atlantic Oscillation and global mean surface air temperature. The observed large-scale change in freshwater flux has potentially important implications for ocean circulation and climate. 相似文献
119.
A physical map of the 1-gigabase bread wheat chromosome 3B 总被引:2,自引:0,他引:2
Paux E Sourdille P Salse J Saintenac C Choulet F Leroy P Korol A Michalak M Kianian S Spielmeyer W Lagudah E Somers D Kilian A Alaux M Vautrin S Bergès H Eversole K Appels R Safar J Simkova H Dolezel J Bernard M Feuillet C 《Science (New York, N.Y.)》2008,322(5898):101-104
As the staple food for 35% of the world's population, wheat is one of the most important crop species. To date, sequence-based tools to accelerate wheat improvement are lacking. As part of the international effort to sequence the 17-billion-base-pair hexaploid bread wheat genome (2n = 6x = 42 chromosomes), we constructed a bacterial artificial chromosome (BAC)-based integrated physical map of the largest chromosome, 3B, that alone is 995 megabases. A chromosome-specific BAC library was used to assemble 82% of the chromosome into 1036 contigs that were anchored with 1443 molecular markers, providing a major resource for genetic and genomic studies. This physical map establishes a template for the remaining wheat chromosomes and demonstrates the feasibility of constructing physical maps in large, complex, polyploid genomes with a chromosome-based approach. 相似文献
120.
This study addresses the influence of three different land use systems (continuous maize, pasture/maize rotation, permanent pasture) on the relationships between earthworm populations and the number of earthworm burrows quantified in a soil profile. Quantified burrows were limited to those observable by the naked eye (i.e. >2 mm in diameter) and enumerated earthworms were limited to those which could have created the observable burrows (i.e. >0.3 g).The results were combined with data from the literature coming from different geographical regions. This study showed that earthworm abundance decreased with the increasing land management intensity (maize crop vs. pasture), while the number of burrows could be higher or similar under maize compared to pasture. Under maize, despite lower earthworm abundance and the annual destruction of the burrows by tillage, the number of burrows was almost as high as under pasture. This absence of a relationship between burrow numbers and earthworm abundance was observed in the soil profile and for each layer of the profile for each land use system. Furthermore, the burrow number/m?2 per earthworm strongly varied depending on land use and was far higher under maize when compared to pasture (74 vs. 7). Therefore, a power-law type relationship was clearly established between burrow number/m?2 per earthworm and earthworm abundance. This power type relationship was also observed when including data from the literature although it followed a different mathematical model. These results were explained by (i) increased earthworm burrowing activity (i.e. an increase in the number of burrows produced by each earthworm) under maize, and (ii) the dynamics of burrow number under pasture (i.e. decreased burrowing activity and burrow destruction process); both results of food accessibility combined with inter-individual competition. The results of the study suggest that farmers should not use the number of pores as an indicator of earthworm abundance, but as an indicator of earthworm activity, which could be integrated in an indicator of soil quality. 相似文献