全文获取类型
收费全文 | 3057篇 |
免费 | 252篇 |
出版年
2021年 | 22篇 |
2020年 | 18篇 |
2019年 | 20篇 |
2018年 | 28篇 |
2017年 | 29篇 |
2016年 | 46篇 |
2015年 | 69篇 |
2014年 | 86篇 |
2013年 | 125篇 |
2012年 | 167篇 |
2011年 | 150篇 |
2010年 | 93篇 |
2009年 | 85篇 |
2008年 | 132篇 |
2007年 | 135篇 |
2006年 | 144篇 |
2005年 | 132篇 |
2004年 | 131篇 |
2003年 | 145篇 |
2002年 | 171篇 |
2001年 | 50篇 |
2000年 | 42篇 |
1999年 | 45篇 |
1998年 | 55篇 |
1997年 | 50篇 |
1996年 | 57篇 |
1995年 | 51篇 |
1994年 | 54篇 |
1993年 | 39篇 |
1992年 | 34篇 |
1991年 | 31篇 |
1990年 | 33篇 |
1989年 | 33篇 |
1988年 | 25篇 |
1987年 | 28篇 |
1986年 | 34篇 |
1985年 | 35篇 |
1984年 | 48篇 |
1983年 | 34篇 |
1982年 | 42篇 |
1981年 | 42篇 |
1980年 | 36篇 |
1979年 | 20篇 |
1978年 | 25篇 |
1977年 | 23篇 |
1976年 | 24篇 |
1975年 | 24篇 |
1974年 | 31篇 |
1970年 | 22篇 |
1968年 | 22篇 |
排序方式: 共有3309条查询结果,搜索用时 20 毫秒
991.
Siu-Leung Lee Heinz G. Floss Peter Heinstein 《Archives of biochemistry and biophysics》1976,177(1):84-94
Dimethylallylpyrophosphate:l-tryptophan dimethylallyltransferase (DMAT synthetase), the first pathway-specific enzyme of ergot alkaloid biosynthesis, has been isolated from mycelia of Claviceps sp., strain SD 58, and purified to apparent homogeneity. The enzyme reaction products were identified as l-4-(γ,γ-dimethylallyl)tryptophan and inorganic pyrophosphate. DMAT synthetase is a single subunit protein of molecular weight 70,000–73,000 and has an isoelectric point at pH 5.8. The enzyme is activated by Fe2+, Mg2+, and particularly Ca2+; Km values for l-tryptophan and dimethylallylpyrophosphate were determined to be 0.067 and 0.2 mm, respectively. Kinetic analysis indicated that the DMAT synthetase reaction proceeds by a sequential rather than a ping-pong mechanism. 相似文献
992.
993.
994.
Sónia Barbosa Dagmar Pratte Heinz Schwarz Rüdiger Pipkorn Birgit Singer‐Krüger 《Traffic (Copenhagen, Denmark)》2010,11(8):1092-1106
Yeast Dop1p is an essential protein that is highly conserved in evolution and whose function is largely unknown. Here, we provide evidence that Dop1p localizes to endosomes and exists in a complex with two other conserved proteins: Neo1p, a P4‐ATPase and putative flippase, and the scaffolding protein Ysl2p/Mon2p. The latter operates during membrane budding at the tubular endosomal network/trans‐Golgi network (TEN/TGN) in a process that includes clathrin recruitment via adaptor proteins. Consistent with a role for Dop1p during this process, temperature‐sensitive dop1‐3 cells accumulate multivesicular, elongated tubular and ring‐like structures similar to those displayed by neo1 and ysl2 mutants. In further agreement with the concept of Dop1p‐Neo1p‐Ysl2p complex formation and co‐operation, we show that dop1‐3 cells exhibit reduced levels of Neo1p and Ysl2p at steady state. Conversely, mutations or deletions in NEO1 and YSL2 lead to a decrease in Dop1p levels. In addition to binding to Neo1p and Ysl2p, Dop1p can form dimers or multimers. A critical region for dimerization resides in the C‐terminus with leucine zipper‐like domains. Dop1p's membrane association is largely mediated by its internal region, but Ysl2p might not be crucial for membrane recruitment. 相似文献
995.
996.
997.
998.
999.
1000.
Janusz Dabrowski Peter Hanfland Heinz Egge Ursula Dabrowski 《Archives of biochemistry and biophysics》1981,210(1):405-411
The Lea-, Leb-, and H-type 1 (LedH)-blood-group-active glycosphingolipids, as well as H-I-type 2 glycolipid, lactotetraosyl ceramide, and neo-lactotetraosyl ceramide were examined by 1H nuclear magnetic resonance at 360 MHz in dimethyl-d6 sulfoxide as solvent. The resonances of almost all protons of the sugar rings were assigned with the aid of spin decoupling and nuclear Overhauser difference spectroscopy. The latter technique was also applied to establish the sequences and sites of glycosidic linkage. This information, combined with the chemical shift-structure correlations established in our previous work, led to an independent identification of those six glycolipids. Type 1 (Galβ1 → 3GlcNAc) and type 2 (Galβ1 → 4GlcNAc) saccharide chains can be distinguished by this approach. Some deviations from additivity in chemical shifts, calculated for oligosaccharides from the data on their constituent sugar residues, furnished information on the conformational changes in crowded glycolipid molecules. 相似文献