全文获取类型
收费全文 | 7229篇 |
免费 | 525篇 |
国内免费 | 3篇 |
出版年
2022年 | 35篇 |
2021年 | 88篇 |
2020年 | 62篇 |
2019年 | 76篇 |
2018年 | 97篇 |
2017年 | 93篇 |
2016年 | 135篇 |
2015年 | 226篇 |
2014年 | 277篇 |
2013年 | 350篇 |
2012年 | 431篇 |
2011年 | 420篇 |
2010年 | 269篇 |
2009年 | 267篇 |
2008年 | 333篇 |
2007年 | 381篇 |
2006年 | 316篇 |
2005年 | 298篇 |
2004年 | 264篇 |
2003年 | 294篇 |
2002年 | 267篇 |
2001年 | 51篇 |
2000年 | 40篇 |
1999年 | 71篇 |
1998年 | 87篇 |
1997年 | 61篇 |
1996年 | 50篇 |
1995年 | 69篇 |
1994年 | 58篇 |
1993年 | 60篇 |
1992年 | 64篇 |
1991年 | 69篇 |
1990年 | 49篇 |
1989年 | 49篇 |
1988年 | 67篇 |
1987年 | 54篇 |
1986年 | 43篇 |
1985年 | 67篇 |
1984年 | 51篇 |
1983年 | 55篇 |
1982年 | 75篇 |
1981年 | 70篇 |
1980年 | 71篇 |
1979年 | 54篇 |
1978年 | 61篇 |
1977年 | 45篇 |
1976年 | 61篇 |
1975年 | 40篇 |
1974年 | 39篇 |
1968年 | 35篇 |
排序方式: 共有7757条查询结果,搜索用时 171 毫秒
241.
Karl Enquist Mawritz Fransson Carolina Boekel Inger Bengtsson Lisa Lang Sofia Johansson IngMarie Nilsson 《Journal of molecular biology》2009,387(5):1153-354
To what extent do corresponding transmembrane helices in related integral membrane proteins have different membrane-insertion characteristics? Here, we compare, side-by-side, the membrane insertion characteristics of the 12 transmembrane helices in the adenosine triphosphate-binding cassette (ABC) transporters, P-glycoprotein (P-gp) and the cystic fibrosis transmembrane conductance regulator (CFTR). Our results show that 10 of the 12 CFTR transmembrane segments can insert independently into the ER membrane. In contrast, only three of the P-gp transmembrane segments are independently stable in the membrane, while the majority depend on the presence of neighboring loops and/or transmembrane segments for efficient insertion. Membrane-insertion characteristics can thus vary widely between related proteins. 相似文献
242.
243.
244.
Methanol extracts from the alga Enteromorpha compressa (L.) Grev. contain substances which inhibit the elongation of Lepidium roots. Chromatographic separation of the inhibiting substances revealed that one of the inhibitory zones of the chromatograms had properties of the so-called inhibitor β. Neither abscisic acid (ABA) nor lunularic acid proved to be responsible for the growth-inhibiting property of this zone. Moreover, the extracts contain substances which promote the elongation of Avena coleoptile segments. One of these substances could be tentatively identified as indole-3-acetic acid by thin-layer and gas-liquid chromatography. (In addition to indole-3-acetic acid a second growth-promoting factor with the properties of the so-called accelerator α could be detected.) 相似文献
245.
246.
247.
The fine structure of the male and female gametes of Pseudobryopsis, particularly that of the flagellar apparatus, is compared with that of swarmers of other green algae. There is general similarity, with differences in detail, to the Ulvales and other green siphons that have been studied. The similarities include overlapping basal bodies, the capping plate type of connective between basal bodies, terminal caps, and system II fibrous roots (rhizoplasts). The capping plate of the female gamete differs from that in other green siphons and the Ulvales in form and in the presence of a faint striation. A diagram illustrating the actual arrangement of the components of the flagellar apparatus is given, along with a discussion of the fact that the mirror image of the true arrangement has been given in some reports on ulvaphycean algae. 相似文献
248.
249.
Karl L. Schuchmann 《Journal of Ornithology》1977,118(2):200-201
Ohne Zusammenfassung 相似文献
250.