全文获取类型
收费全文 | 33653篇 |
免费 | 2908篇 |
国内免费 | 122篇 |
出版年
2021年 | 472篇 |
2020年 | 308篇 |
2019年 | 449篇 |
2018年 | 522篇 |
2017年 | 440篇 |
2016年 | 683篇 |
2015年 | 1092篇 |
2014年 | 1170篇 |
2013年 | 1688篇 |
2012年 | 1880篇 |
2011年 | 1730篇 |
2010年 | 1268篇 |
2009年 | 1020篇 |
2008年 | 1494篇 |
2007年 | 1441篇 |
2006年 | 1391篇 |
2005年 | 1252篇 |
2004年 | 1295篇 |
2003年 | 1183篇 |
2002年 | 1250篇 |
2001年 | 1111篇 |
2000年 | 1023篇 |
1999年 | 895篇 |
1998年 | 450篇 |
1997年 | 451篇 |
1996年 | 340篇 |
1995年 | 360篇 |
1994年 | 268篇 |
1993年 | 316篇 |
1992年 | 615篇 |
1991年 | 555篇 |
1990年 | 556篇 |
1989年 | 505篇 |
1988年 | 409篇 |
1987年 | 392篇 |
1986年 | 374篇 |
1985年 | 428篇 |
1984年 | 388篇 |
1983年 | 340篇 |
1982年 | 244篇 |
1981年 | 256篇 |
1980年 | 241篇 |
1979年 | 329篇 |
1978年 | 284篇 |
1977年 | 316篇 |
1976年 | 280篇 |
1975年 | 277篇 |
1974年 | 290篇 |
1973年 | 267篇 |
1972年 | 232篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
91.
92.
93.
94.
The interaction of jatrophone with sRNA from Escherichia coli has been investigated through UV, CD, and 1H NMR measurements. The results obtained show that the interaction with jatrophone increases the stability of the polynucleotide. It appears that the optical properties of jatrophone depend upon the jatrophone/nucleotide ratio. The observed behaviour can only be explained by the existence of different types of interaction between jatrophone and sRNA. Even for a jatrophone/nucleotide ratio as low as 0.17 the 1H NMR spectra show a multiplicity of resonances that can only be explained by the simultaneous existence of two different binding modes involving the jatrophone molecules. 相似文献
95.
Pollens from Pinus canariensis, P. nigra, P. pinaster, P. pinea, Castanea sativa, Magnolia grandiflora, Olea sativa cv frantoio, cv itrana, cv pisciottana were examined for their free amino acid composition. A large amount of proline was found in all species; pollens of Olea also contain a large amount of serine. 相似文献
96.
97.
A J De Siervo 《Canadian journal of biochemistry》1975,53(9):1031-1034
Using membrane preparations of Micrococcus lysodeikticus, the end-products of cardiolipin synthesis, cardiolipin and glycerol, were shown to inhibit cardiolipin synthetase at several concentrations. Other phospholipids tested for inhibitory effects, phosphatidyl-ethanolamine, phosphatidylinositol, and phosphatidic acid were also shown to inhibit cardiolipin synthesis. Phosphatidic acid was considerably more inhibitory than cardiolipin, phosphatidylethanolamine was similar to cardiolipin, and phosphatidylinositol less inhibitory at the same concentrations. A non-phosphate-containing glycolipid was also inhibitory. In contrast, glycerophosphate had no effect on cardiolipin synthesis. 相似文献
98.
99.
100.
The influence of the substituents upon the Amide I and νNH frequencies has been analyzed for ten amides substituted by aliphatic side chains. By considering the aliphatic chain field effect, some data are obtained as to the conformation of the N? Cα bond. In two amides, the presence of an equilibrium between two conformers is shown and a semiquantitative estimation of the energies involved is obtained. The consequences for polypeptides conformation, especially for poly-L -valine, are discussed. 相似文献