全文获取类型
收费全文 | 1149篇 |
免费 | 57篇 |
国内免费 | 2篇 |
专业分类
林业 | 100篇 |
农学 | 39篇 |
基础科学 | 11篇 |
254篇 | |
综合类 | 189篇 |
农作物 | 46篇 |
水产渔业 | 94篇 |
畜牧兽医 | 336篇 |
园艺 | 57篇 |
植物保护 | 82篇 |
出版年
2023年 | 7篇 |
2022年 | 5篇 |
2021年 | 24篇 |
2020年 | 24篇 |
2019年 | 31篇 |
2018年 | 33篇 |
2017年 | 29篇 |
2016年 | 27篇 |
2015年 | 30篇 |
2014年 | 34篇 |
2013年 | 60篇 |
2012年 | 71篇 |
2011年 | 89篇 |
2010年 | 53篇 |
2009年 | 48篇 |
2008年 | 78篇 |
2007年 | 65篇 |
2006年 | 70篇 |
2005年 | 60篇 |
2004年 | 44篇 |
2003年 | 48篇 |
2002年 | 50篇 |
2001年 | 8篇 |
2000年 | 11篇 |
1999年 | 10篇 |
1997年 | 4篇 |
1992年 | 6篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1979年 | 4篇 |
1978年 | 7篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1975年 | 9篇 |
1974年 | 4篇 |
1973年 | 7篇 |
1972年 | 4篇 |
1970年 | 4篇 |
1969年 | 9篇 |
1968年 | 5篇 |
1967年 | 8篇 |
1966年 | 6篇 |
1965年 | 4篇 |
1930年 | 5篇 |
排序方式: 共有1208条查询结果,搜索用时 15 毫秒
991.
We studied the free fluid-fluid interface in a phase-separated colloid-polymer dispersion with laser scanning confocal microscopy and directly observed thermally induced capillary waves at the interface in real space. Experimental results for static and dynamic correlation functions validate the capillary wave model down to almost the particle level. The ultralow interfacial tension, the capillary length, and the capillary time are found to be in agreement with independent measurements. Furthermore, we show that capillary waves induce the spontaneous breakup of thin liquid films and thus are of key importance in the process of droplet coalescence. 相似文献
992.
Xiong JP Stehle T Zhang R Joachimiak A Frech M Goodman SL Arnaout MA 《Science (New York, N.Y.)》2002,296(5565):151-155
The structural basis for the divalent cation-dependent binding of heterodimeric alphabeta integrins to their ligands, which contain the prototypical Arg-Gly-Asp sequence, is unknown. Interaction with ligands triggers tertiary and quaternary structural rearrangements in integrins that are needed for cell signaling. Here we report the crystal structure of the extracellular segment of integrin alphaVbeta3 in complex with a cyclic peptide presenting the Arg-Gly-Asp sequence. The ligand binds at the major interface between the alphaV and beta3 subunits and makes extensive contacts with both. Both tertiary and quaternary changes are observed in the presence of ligand. The tertiary rearrangements take place in betaA, the ligand-binding domain of beta3; in the complex, betaA acquires two cations, one of which contacts the ligand Asp directly and the other stabilizes the ligand-binding surface. Ligand binding induces small changes in the orientation of alphaV relative to beta3. 相似文献
993.
Activation of endothelial cell protease activated receptor 1 by the protein C pathway 总被引:1,自引:0,他引:1
The coagulant and inflammatory exacerbation in sepsis is counterbalanced by the protective protein C (PC) pathway. Activated PC (APC) was shown to use the endothelial cell PC receptor (EPCR) as a coreceptor for cleavage of protease activated receptor 1 (PAR1) on endothelial cells. Gene profiling demonstrated that PAR1 signaling could account for all APC-induced protective genes, including the immunomodulatory monocyte chemoattractant protein-1 (MCP-1), which was selectively induced by activation of PAR1, but not PAR2. Thus, the prototypical thrombin receptor is the target for EPCR-dependent APC signaling, suggesting a role for this receptor cascade in protection from sepsis. 相似文献
994.
Aeolian deposits in the Wahiba Sands, Sultanate of Oman, reveal patterns of atmospheric circulation over the past 160,000 years. Luminescence dating indicates a correlation of dune activity with periods of low global sea level and decreased monsoon intensity. Evidence from dune orientation and sedimentary structures shows exclusively northbound transport of sand during times of high- latitude glaciation. These results are in contrast to the current paleocirculation model that assumes an increase of northwesterly winds because of a southward shift of the Intertropical Convergence Zone. Our results indicate that the circulation pattern during glacial times was comparable to that of the present. 相似文献
995.
Eisele YS Obermüller U Heilbronner G Baumann F Kaeser SA Wolburg H Walker LC Staufenbiel M Heikenwalder M Jucker M 《Science (New York, N.Y.)》2010,330(6006):980-982
The intracerebral injection of β-amyloid-containing brain extracts can induce cerebral β-amyloidosis and associated pathologies in susceptible hosts. We found that intraperitoneal inoculation with β-amyloid-rich extracts induced β-amyloidosis in the brains of β-amyloid precursor protein transgenic mice after prolonged incubation times. 相似文献
996.
997.
Geballe TH Matthias BT Andres K Maita JP Cooper AS Corenzwit E 《Science (New York, N.Y.)》1968,160(3835):1443-1444
Magnetic ordering in the rare-earth hexaborides has been studied by a variety of methods, and a clear correlation with the presence of conduction electrons has been found. 相似文献
998.
Matthias BT Geballe TH Andres K Corenzwit E Hull GW Maita JP 《Science (New York, N.Y.)》1968,159(3814):530
Ferromagnetism, antiferromagnetism, or superconductivity has been discovered in most hexa- and dodecaborides. 相似文献
999.
Dietrich FS Voegeli S Brachat S Lerch A Gates K Steiner S Mohr C Pöhlmann R Luedi P Choi S Wing RA Flavier A Gaffney TD Philippsen P 《Science (New York, N.Y.)》2004,304(5668):304-307
We have sequenced and annotated the genome of the filamentous ascomycete Ashbya gossypii. With a size of only 9.2 megabases, encoding 4718 protein-coding genes, it is the smallest genome of a free-living eukaryote yet characterized. More than 90% of A. gossypii genes show both homology and a particular pattern of synteny with Saccharomyces cerevisiae. Analysis of this pattern revealed 300 inversions and translocations that have occurred since divergence of these two species. It also provided compelling evidence that the evolution of S. cerevisiae included a whole genome duplication or fusion of two related species and showed, through inferred ancient gene orders, which of the duplicated genes lost one copy and which retained both copies. 相似文献
1000.