全文获取类型
收费全文 | 3052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 | 70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 | 35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 | 23篇 |
1975年 | 21篇 |
1974年 | 29篇 |
1970年 | 22篇 |
1968年 | 22篇 |
排序方式: 共有3304条查询结果,搜索用时 265 毫秒
991.
992.
993.
994.
995.
996.
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
997.
998.
Nucleic acid hybridization and cell wall composition studies of pyogenic streptococci 总被引:2,自引:0,他引:2
Abstract DNA-rRNA and DNA-DNA hybridization studies indicate that the classical pyogenic streptococci can be divided into five homology clusters. Based on these studies the term pyogenic streptococci should be confined to the first cluster consisting of serological groups A, A-variant, C, G ('large' colony, type II) and L.
Streptococci of serological groups B and M form the second cluster. The third cluster is composed of streptococci of serological groups R and S and serological groups U, V and P are found in the fourth cluster. The fifth cluster comprises strains of Streptococcus anginosus S. intermedius, Streptococcus MG and serological groups G ('minute' colony, type I) and F (type I). Most of the test strains contain the peptidoglycan type Lys-Ala1–3 . Only streptococci of serogroups R and S reveal a directly cross-linked peptidoglycan. Rhamnose was found as characteristic component of all cell wall polysaccharides. The impact of our results on the systematics of classical pyogenic streptococci will be discussed. 相似文献
Streptococci of serological groups B and M form the second cluster. The third cluster is composed of streptococci of serological groups R and S and serological groups U, V and P are found in the fourth cluster. The fifth cluster comprises strains of Streptococcus anginosus S. intermedius, Streptococcus MG and serological groups G ('minute' colony, type I) and F (type I). Most of the test strains contain the peptidoglycan type Lys-Ala
999.
The fadD gene of Escherichia coli K12 was cloned and sequenced. The gene was identified by its ability to complement the corresponding mutant and by measuring the enzymatic activity after its expression in this mutant. The deduced polypeptide sequence exhibits similarity to other long chain acyl-CoA (coenzyme A) synthetases and a variety of other proteins, which together form a family of AMP-binding proteins. This family is extended by several new members and subdivided into four groups. fadD is assigned to a subgroup that does not include long chain acyl-CoA synthetases from eukaryotic organisms. 相似文献
1000.