全文获取类型
收费全文 | 4554篇 |
免费 | 443篇 |
国内免费 | 4篇 |
出版年
2023年 | 25篇 |
2022年 | 47篇 |
2021年 | 120篇 |
2020年 | 62篇 |
2019年 | 75篇 |
2018年 | 92篇 |
2017年 | 75篇 |
2016年 | 122篇 |
2015年 | 227篇 |
2014年 | 245篇 |
2013年 | 285篇 |
2012年 | 326篇 |
2011年 | 322篇 |
2010年 | 218篇 |
2009年 | 163篇 |
2008年 | 239篇 |
2007年 | 232篇 |
2006年 | 204篇 |
2005年 | 194篇 |
2004年 | 190篇 |
2003年 | 183篇 |
2002年 | 137篇 |
2001年 | 71篇 |
2000年 | 64篇 |
1999年 | 59篇 |
1998年 | 51篇 |
1997年 | 40篇 |
1996年 | 36篇 |
1995年 | 34篇 |
1994年 | 39篇 |
1993年 | 40篇 |
1992年 | 55篇 |
1991年 | 55篇 |
1990年 | 52篇 |
1989年 | 49篇 |
1988年 | 42篇 |
1987年 | 48篇 |
1986年 | 34篇 |
1985年 | 44篇 |
1984年 | 33篇 |
1983年 | 32篇 |
1982年 | 25篇 |
1981年 | 18篇 |
1980年 | 25篇 |
1979年 | 28篇 |
1978年 | 25篇 |
1976年 | 19篇 |
1975年 | 28篇 |
1973年 | 20篇 |
1968年 | 18篇 |
排序方式: 共有5001条查询结果,搜索用时 265 毫秒
71.
A diverse collection of actinomycete strains were screened for production of extracellular peroxidase activity by adapting a chemiluminescence analysis system developed for horseradish peroxidase-based enzyme-linked immunosorbent assay. Extracellular peroxidase activity was found to be common but quantitatively variable, and this rapid and sensitive screening system permitted identification of a small group of high-producing strains. A range of spectrophotometric assays were compared for the measurement of peroxidase activity in concentrated culture supernatants of two selected thermophilic streptomycetes. Of these, the peroxide-dependent oxidation of 2,4-dichlorophenol was identified as the most robust and reproducible assay for quantitative studies. 相似文献
72.
73.
74.
Françoise Mead Catherine Habersetzer Danielle Gabouriaut Jacques Gervet 《Journal of Ethology》1994,12(1):43-51
This study focused on how a decrease in prey availability affected the development of aP. dominulus Christ colony. Nutritional oophagy and larval development were parameters found to be most directly affected. The more indirect
effects on the growth of the nest and on offspring production were also analyzed. 相似文献
75.
Prof. Danielle Swinne 《Mycopathologia》1994,128(2):65-65
Editor's Note. Dr Vanbreuseghem was a member of the Mycopathologia Educational Board from 1959 to 1960. 相似文献
76.
International dissemination of epidemic Vibrio cholerae by cargo ship ballast and other nonpotable waters. 总被引:4,自引:1,他引:3 下载免费PDF全文
In 1991 and 1992, toxigenic Vibrio cholerae O1, serotype Inaba, biotype El Tor, was recovered from nonpotable (ballast, bilge, and sewage) water from five cargo ships docked in ports of the U.S. Gulf of Mexico. Four of these ships had taken on ballast water in cholera-infected countries; the fifth took on ballast in a noninfected country. Isolates examined by pulsed-field gel electrophoresis were indistinguishable from the Latin American epidemic strain, C6707; however, they differed significantly from the endemic Gulf Coast strain (VRL 1984), the sixth-pandemic strain (569-B), and a V. cholerae non-O1 strain isolated from a ship arriving from a foreign port. On the basis of our findings, the Food and Drug Administration recommended that the U.S. Coast Guard issue an advisory to shipping agents and captains requesting that ballast waters be exchanged on the high seas before entry of ships into U.S. ports. 相似文献
77.
78.
79.
An antibody- and synthetic peptide-defined rubella virus E1 glycoprotein neutralization domain. 总被引:6,自引:0,他引:6 下载免费PDF全文
J S Wolinsky E Sukholutsky W T Moore A Lovett M McCarthy B Adame 《Journal of virology》1993,67(2):961-968
We previously described a monoclonal antibody (MAb) library generated by infecting BALB/c mice with rubella virus (RV) and selected by an enzyme-linked immunosorbent assay (ELISA) using purified virion targets. Plasmid pARV02-01, which expresses the fusion protein RecA1-35-GIGDLGSP-E1(202)-E1(283)-GDP-LacZ9-1015 in Escherichia coli, was shown to be a ligand for MAbs E1-18 and E1-20 (J. S. Wolinsky, M. McCarthy, O. Allen-Cannady, W. T. Moore, R. Jin, S. N. Cao, A. Lovett, and D. Simmons, J. Virol. 65:3986-3994, 1991). Both of these MAbs neutralize RV infectivity. A series of five overlapping synthetic peptides was made to further explore the requirements of this MAb binding domain. One of these peptides (SP15; E1(208) to E1(239)) proved an effective ligand for both MAbs in the ELISA. Stepwise synthesis of SP15 defined the minimal amino-terminal requirement for binding MAb E1-18 as E1(221) and that of MAb E1-20 as E1(223); the minimal carboxyl-terminal requirement is uncertain but does not exceed E1(239). Immunization of mice and rabbits with SP15 induced polyvalent antibody reactive with SP15, with other overlapped and related but not unrelated synthetic peptides, and with RV. The rabbit anti-SP15 antibody showed neutralization activity to RV similar to that of MAbs E1-18 and E1-20 but lacked hemagglutination inhibition activity. These data define a neutralization domain on E1 and suggest that the RV epitopes conserved by SP15 may be critical for protective host humoral immune responses. 相似文献
80.