全文获取类型
收费全文 | 5459篇 |
免费 | 484篇 |
国内免费 | 1篇 |
出版年
2023年 | 22篇 |
2022年 | 21篇 |
2021年 | 101篇 |
2020年 | 62篇 |
2019年 | 79篇 |
2018年 | 88篇 |
2017年 | 81篇 |
2016年 | 135篇 |
2015年 | 254篇 |
2014年 | 261篇 |
2013年 | 329篇 |
2012年 | 414篇 |
2011年 | 427篇 |
2010年 | 266篇 |
2009年 | 222篇 |
2008年 | 325篇 |
2007年 | 333篇 |
2006年 | 322篇 |
2005年 | 289篇 |
2004年 | 285篇 |
2003年 | 242篇 |
2002年 | 225篇 |
2001年 | 82篇 |
2000年 | 84篇 |
1999年 | 89篇 |
1998年 | 62篇 |
1997年 | 61篇 |
1996年 | 41篇 |
1995年 | 53篇 |
1994年 | 51篇 |
1993年 | 39篇 |
1992年 | 49篇 |
1991年 | 36篇 |
1990年 | 47篇 |
1989年 | 37篇 |
1988年 | 35篇 |
1987年 | 37篇 |
1986年 | 26篇 |
1985年 | 34篇 |
1984年 | 29篇 |
1983年 | 24篇 |
1982年 | 19篇 |
1981年 | 27篇 |
1980年 | 22篇 |
1979年 | 23篇 |
1978年 | 16篇 |
1976年 | 12篇 |
1975年 | 15篇 |
1973年 | 11篇 |
1971年 | 17篇 |
排序方式: 共有5944条查询结果,搜索用时 15 毫秒
1.
2.
G Kh Goldshte?ne I B Tsorin G G Chichkanov 《Biulleten' eksperimental'no? biologii i meditsiny》1986,101(2):177-179
The experiments on rats with a 3-day myocardial infarction caused by the left coronary artery ligation have shown that multiple lidocaine and pyromecaine injections according to a given scheme decrease the size of the necrosis area. Drug effects were not related to their action on the blood supply of the ischemic area. 相似文献
3.
4.
The Rd gene is expressed in the livers and oviducts of laying hens and codes for the riboflavin-binding protein (RfBP) of egg yolk and egg white. A lambda gt11 cDNA library derived from chicken oviduct poly(A)+ RNA was screened with polyclonal rabbit antiserum to chicken RfBP. Positive clones were isolated and rescreened with a mixed oligonucleotide probe corresponding to residues 20-25 of the mature protein. The largest cDNA clone (969 base pairs) was subcloned into plasmid pIBI21, and the nucleotide sequence was determined by the dideoxynucleotide method. This clone contained the entire coding region for RfBP. The published amino acid sequence of the mature protein was confirmed. In addition, the following 17-residue signal peptide was deduced: Met-Leu-Arg-Phe-Ala-Ile-Thr-Leu-Phe-Ala-Val-Ile-Thr-Ser-Ser-Thr-Cys. Unexpectedly, the nucleotide sequence codes for 2 adjacent arginine residues at the carboxyl terminus that are not observed in the mature protein. The amino acid sequence of RfBP is homologous with bovine milk folate-binding protein. Eight of the nine pairs of cysteines involved in disulfide bonds in RfBP are conserved in folate-binding protein, as are all of the tryptophan residues. Sequence identity between homologous regions of these two vitamin-binding proteins is more than 30%. 相似文献
5.
6.
T I Grand 《American journal of physical anthropology》1968,28(2):163-181
The howler monkey possesses unique anatomical adaptations associated with its arboreal habit. The behavioral elements are described by locomotor pattern, substrate, timing and rhythm of movement. The most significant motor adaptations are correlated clearly and directly with musculoskeletal features of the lower limb. The orientation of the joints within the limb, the shape of the joint surfaces, their bony environments, and the important planes of muscular control are the foundations for the observable locomotor behaviors. 相似文献
7.
Didier Arseguel Armand Lattes Michel Baboul ne 《Biocatalysis and Biotransformation》1990,3(3):217-225
Horseradish peroxidase was chemically conjugated on its carbohydrate moieties with short aliphatic chains (C8 and C16). An analytical method using FT.IR spectroscopy was developed to analyze this alteration in enzyme structure. This method is non-destructive, and can be applied directly to samples of the reaction mixture. More general applications of this technique are described and discussed. 相似文献
8.
R J Grand 《The Biochemical journal》1989,258(3):625-638
9.
10.
Mutations affecting the catalytic activity of Bacillus cereus 5/B/6 beta-lactamase II 总被引:2,自引:0,他引:2
Random in vitro mutagenesis of a cloned Bacillus cereus 5/B/6 beta-lactamase II gene was used to select defective genes unable to confer ampicillin or cephalosporin C resistance to Escherichia coli. DNA sequencing of mutant genes identified histidine at position 28 as important to beta-lactamase II function. In addition, the isolation of six identical frameshift mutants established that the carboxyl-terminal end of beta-lactamase II is critical for enzyme function. Random mutagenesis also revealed that His88 (implicated previously as one of 4 residues acting as a zinc ligand) is crucial to enzymatic activity and that a glycine to glutamic acid substitution at position 148 produced a defective beta-lactamase. Oligonucleotide mutagenesis directed at Glu37 and Glu212 suggests that these residues are inconsequential to enzyme function but that histidine at position 28 may be involved in substrate binding or recognition. 相似文献