全文获取类型
收费全文 | 884篇 |
免费 | 20篇 |
国内免费 | 3篇 |
出版年
2019年 | 8篇 |
2018年 | 16篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 7篇 |
2014年 | 57篇 |
2013年 | 49篇 |
2012年 | 44篇 |
2011年 | 48篇 |
2010年 | 51篇 |
2009年 | 38篇 |
2008年 | 40篇 |
2007年 | 62篇 |
2006年 | 42篇 |
2005年 | 40篇 |
2004年 | 18篇 |
2003年 | 11篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1987年 | 2篇 |
1985年 | 27篇 |
1984年 | 42篇 |
1983年 | 32篇 |
1982年 | 48篇 |
1981年 | 43篇 |
1980年 | 31篇 |
1979年 | 30篇 |
1978年 | 19篇 |
1977年 | 23篇 |
1976年 | 19篇 |
1975年 | 10篇 |
1974年 | 4篇 |
1973年 | 9篇 |
1972年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有907条查询结果,搜索用时 15 毫秒
1.
S C Tsai R Adamik V C Manganiello M Vaughan 《Biochemical and biophysical research communications》1981,100(2):637-643
A new amino acid was isolated from the cuticle collagen of and characterized by ultraviolet, mass and nmr spectroscopies and chemical degradation. The results indicate that the compound is an isomer of trityrosine, having an ether linkage. The name “isotrityrosine” is proposed. Its structure suggests that it serves as a crosslink and plays a role in the organization of the collagen structure. 相似文献
2.
F H Stephenson 《Gene》1985,35(3):313-320
3.
4.
ATP-dependent deoxyribonuclease in Bacillus subtilis and a mutant deficient in this activity 总被引:13,自引:0,他引:13
ATP-dependent DNAse activity was measured in rec+ and several rec strains of B. subtilis 168. One of the strains (marker recE5) was found to lack this activity. The enzyme from the wild type was partially purified and some of its properties were determined. The pH optimum is 9.5. Activity is higher at 50° but inactivation occurs on standing at this temperature. The enzyme requires Mg2+ (10?2M) or Mn2+ (2·10?4M). ATP is an absolute requirement and the only other nucleoside triphosphate that can partially replace it is dATP. Lack of activity in the mutant does not seem to be due to the presence of an inhibitor. Results so far do not allow us to conclude as to whether or not the mutant produces an altered enzyme. 相似文献
5.
J.C. Smith R.B. Derbyshire E. Cook L. Dunthorne J. Viney S.J. Brewer H.M. Sassenfeld L.D. Bell 《Gene》1984,32(3):321-327
A 43-bp DNA duplex coding for poly(arginine) [poly(arg)] has been synthesised by modified phosphotriester procedures. It has been inserted into the BglII and BamHI restriction sites of a cloned synthetic β-urogastrone (Uro) gene, under the control of the trp promoter. Subsequent induction with 3β-indole acrylic acid produces β-Uro with a C-terminal poly(arg) fusion. The raised isoelectric point of this polypeptide fusion facilitates rapid purification by cation exchange chromatography. The C-terminal poly(arg) tail can be readily removed by treatment with carboxypeptidase B. 相似文献
6.
7.
8.
9.
T.G. Adelman P. Arosio J.W. Drysdale 《Biochemical and biophysical research communications》1975,63(4):1056-1062
The subunit composition of human heart and liver ferritins was examined by both sodium dodecyl sulfate gel electrophoresis and acetic acidurea gel electrophoresis. These analyses indicated that both tissues contained two subunit types of similar size but different surface charge. One subunit was common to both tissues. The implications of these findings in relation to the known heterogeneity of isoferritins are discussed, and a new model of ferritin structure is proposed. 相似文献
10.
Hisatoshi Mimura 《BBA》2005,1708(3):393-403
The H+-pyrophosphatase (H+-PPase) consists of a single polypeptide, containing 16 or 17 transmembrane domains. To determine the higher order oligomeric state of Streptomyces coelicolor H+-PPase, we constructed a series of cysteine substitution mutants and expressed them in Escherichia coli. Firstly, we analyzed the formation of disulfide bonds, promoted by copper, in mutants with single cysteine substitutions. 28 of 39 mutants formed disulfide bonds, including S545C, a substitution at the periplasmic side. The formation of intermolecular disulfide bonds suppressed the enzyme activity of several, where the substituted residues were located in the cytosol. Creating disulfide links in the cytosol may interfere with the enzyme's catalytic function. Secondly, we prepared double mutants by introducing second cysteine substitutions into the S545C mutant. These double-cysteine mutants produced cross-linked complexes, estimated to be at least tetramers and possibly hexamers. Thirdly, we co-expressed epitope-tagged, wild type, and inactive mutant H+-PPases in E. coli and confirmed the formation of oligomers by co-purifying one subunit using the epitope tag used to label the other. The enzyme activity of these oligomers was markedly suppressed. We propose that H+-PPase is present as an oligomer made up of at least two or three sets of dimers. 相似文献