全文获取类型
收费全文 | 10189篇 |
免费 | 25篇 |
国内免费 | 37篇 |
专业分类
系统科学 | 30篇 |
丛书文集 | 48篇 |
教育与普及 | 30篇 |
理论与方法论 | 24篇 |
现状及发展 | 3961篇 |
研究方法 | 522篇 |
综合类 | 5468篇 |
自然研究 | 168篇 |
出版年
2012年 | 151篇 |
2011年 | 325篇 |
2010年 | 60篇 |
2009年 | 54篇 |
2008年 | 168篇 |
2007年 | 208篇 |
2006年 | 192篇 |
2005年 | 214篇 |
2004年 | 210篇 |
2003年 | 190篇 |
2002年 | 205篇 |
2001年 | 429篇 |
2000年 | 437篇 |
1999年 | 294篇 |
1996年 | 52篇 |
1994年 | 269篇 |
1992年 | 252篇 |
1991年 | 201篇 |
1990年 | 230篇 |
1989年 | 192篇 |
1988年 | 185篇 |
1987年 | 190篇 |
1986年 | 201篇 |
1985年 | 264篇 |
1984年 | 201篇 |
1983年 | 163篇 |
1982年 | 135篇 |
1981年 | 140篇 |
1980年 | 144篇 |
1979年 | 325篇 |
1978年 | 263篇 |
1977年 | 215篇 |
1976年 | 191篇 |
1975年 | 195篇 |
1974年 | 206篇 |
1973年 | 176篇 |
1972年 | 206篇 |
1971年 | 245篇 |
1970年 | 303篇 |
1969年 | 229篇 |
1968年 | 226篇 |
1967年 | 194篇 |
1966年 | 223篇 |
1965年 | 149篇 |
1959年 | 75篇 |
1958年 | 123篇 |
1957年 | 81篇 |
1956年 | 58篇 |
1954年 | 62篇 |
1948年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 734 毫秒
881.
T Sato 《Experientia》1977,33(9):1165-1167
When frog taste cells were stimulated by varying salts after adaptation to water, quinine or acetic acid, a phasic depolarization appeared initially in the receptor potential of taste cells. The initial transient depolarization may be related to the enhancement of an initial phasic response in the taste nerve. 相似文献
882.
883.
884.
885.
Barton John Pyrch Timothy Koehler Cortus T. 《Systemic Practice and Action Research》2000,13(2):243-254
Rethinking the Fifth Discipline: Learning Within the Unknowable by Robert Louis Flood. Sami Potatoes: Living with Reindeer and Perestroika by Michael Robinson and Karim-Aly Kassam. The Self Managing Organization: How Leading Companies Are Transforming the Work of Teams for Real Impact by Ronald E. Purser and Steven Cabana. 相似文献
886.
Location of functional regions of acetylcholine receptor alpha-subunit by site-directed mutagenesis 总被引:1,自引:0,他引:1
M Mishina T Tobimatsu K Imoto K Tanaka Y Fujita K Fukuda M Kurasaki H Takahashi Y Morimoto T Hirose 《Nature》1985,313(6001):364-369
The availability of cloned cDNAs encoding the four subunits of the Torpedo acetylcholine receptor, which can be expressed to make functional receptors in Xenopus oocytes, has made possible a detailed investigation of the functions of the different structural components of the receptor. The functional analysis of receptors with alpha-subunits altered at specific sites by site-directed mutagenesis of the cDNA has allowed the location of specific regions of the alpha-subunit molecule involved in acetylcholine binding and forming a transmembrane ionic channel. 相似文献
887.
888.
D. E. Dussourd C. A. Harvis J. Meinwald T. Eisner 《Cellular and molecular life sciences : CMLS》1989,45(9):896-898
Summary Pyrrolizidine alkaloid sequestered by adult maleDanaus gilippus from plants is transferred in large measure to the female at mating, and by the female to the eggs. The eggs, presumably, are protected as a result. The male's courtship pheromone, danaidone, derived from the sequestered alkaloid, may function to advertise the male's alkaloid-donating capacity.Acknowledgments. Paper Nr. 89 of the series Defense Mechanisms of Arthropods. Study supported by NIH (Grants AI-02908 and AI-12020; Predoctoral Traineeship to DED), Hatch funds (191-7416), the Bache Fund (National Academy of Sciences, to DED), and the Theodore Roosevelt Memorial Fund (American Museum of Natural History, to DED). We thank M. Weingarner and J. Miller forD. gilippus collection, J. Boggan for technical assistance, and the staff of the Archbold Biological Station, Lake Placid, Florida, for assistance and hospitality. One of us (DED) is indebted to M. D. Achey, who by demonstrating nuptial cardenolide transfer in the monarch butterfly [Honors Thesis, Amherst College, Amherst, Massachusetts (1979)] raised the possibility that other plant metabolites might be similarly transferred in danaines.Deceased July, 1985. This paper is affectionately dedicated to his memory. 相似文献
889.
Structures and functions of annexins in plants 总被引:6,自引:0,他引:6
890.
Activation of the superoxide generating system in human neutrophils is thought to involve the interaction or assembly of cytochrome b with other cytosolic and membrane proteins. We have now co-isolated by conventional purification procedures a protein of relative molecular mass 22,000 with cytochrome b. This Ras-related protein is not a fragment of either of the subunits of cytochrome b, and its primary structure, as determined by the sequencing of its complementary DNA, is identical to that predicted from a recently cloned ras-related gene, rap1 (also termed Krev-1). Immunoaffinity purification on anti-cytochrome and anti-Ras immunoaffinity matrices indicates an association between cytochrome b and the Ras-related protein. The association of a Ras-related GTP-binding protein with cytochrome b of human neutrophils could indicate a role for such a protein in the transduction, regulation or structure of the superoxide generating system. 相似文献