全文获取类型
收费全文 | 501174篇 |
免费 | 48900篇 |
国内免费 | 227篇 |
出版年
2018年 | 4848篇 |
2016年 | 6312篇 |
2015年 | 7229篇 |
2014年 | 9109篇 |
2013年 | 12975篇 |
2012年 | 15012篇 |
2011年 | 15522篇 |
2010年 | 10818篇 |
2009年 | 9716篇 |
2008年 | 13946篇 |
2007年 | 14434篇 |
2006年 | 13777篇 |
2005年 | 13284篇 |
2004年 | 13220篇 |
2003年 | 13081篇 |
2002年 | 12685篇 |
2001年 | 19597篇 |
2000年 | 19340篇 |
1999年 | 15540篇 |
1998年 | 5334篇 |
1997年 | 5301篇 |
1996年 | 5164篇 |
1995年 | 4945篇 |
1994年 | 4940篇 |
1993年 | 4842篇 |
1992年 | 13247篇 |
1991年 | 13241篇 |
1990年 | 13076篇 |
1989年 | 12951篇 |
1988年 | 12152篇 |
1987年 | 11765篇 |
1986年 | 10839篇 |
1985年 | 11202篇 |
1984年 | 9204篇 |
1983年 | 7969篇 |
1982年 | 5963篇 |
1981年 | 5548篇 |
1980年 | 5197篇 |
1979年 | 9070篇 |
1978年 | 7071篇 |
1977年 | 6650篇 |
1976年 | 6417篇 |
1975年 | 7257篇 |
1974年 | 8017篇 |
1973年 | 7871篇 |
1972年 | 7159篇 |
1971年 | 6601篇 |
1970年 | 5747篇 |
1969年 | 5692篇 |
1968年 | 5208篇 |
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
41.
A dot-ELISA technique for the detection of Pseudomonas protease was developedusing IgG of anti- Pseudomonas AFT-36 protease as capture antibody. The detection limitof protease in buffer or milk was 1·01 ng ml−1 . The procedure was performedat room temperature, took about 2·5 h and was economical. Protease AFT-36 isimmunologically related to five out of seven Pseudomonas spp. The results suggest thatthe assay could be used to detect proteases in dairy products. 相似文献
42.
Eighty-five catalase- and oxidase-positive Gram-negative rods and cocci susceptible to penicillin G were isolated from a variety of food sources. The phenotypic relationships of these isolates with reference cultures of Bergeyella -like, Chryseobacterium, Empedobacter, Myroides , Moraxella , Sphingobacterium and Weeksella -like strains were examined by numerical taxonomy. Seventy-three isolates were recovered in five groups; 80% of the isolates clustered in groups 1, 2 and 3 and produced indole, bearing a strong resemblance to Weeksella and Bergeyella . They could not, however, be regarded as belonging to the known species of W. virosa and B. zoohelcum . It is suggested that three species may be necessary to accommodate the environmental Weeksella - or Bergeyella -like bacteria. The isolates in groups 4 and 5 had white colonies and were unable to produce indole, in this way resembling the Moraxella genus. 相似文献
43.
W. D. Roof H. Q. Fang K. D. Young Jianling Sun & Ry Young 《Molecular microbiology》1997,25(6):1031-1046
slyD encodes a 196 amino acid polypeptide that is a member of the FKBP family of cis–trans peptidyl–prolyl isomerases (PPIases). slyD mutations affect plaque formation by the phage φX174 by blocking the action of the phage lysis protein E. Here we describe the selection of a set of spontaneous slyD mutations conferring resistance to the expression of gene E from a plasmid. These mutations occur disproportionately in residues of SlyD that, based on the structure of the prototype mammalian FKBP12, make ligand contacts with immunosuppressing drug molecules or are conserved in other FKBP proteins. A wide variation in the plating efficiency of φX174 on these E R strains is observed, relative to the parental, indicating that these alleles differ widely in residual SlyD activity. Moreover, it is found that slyD mutations cause significant growth rate defects in Escherichia coli B and C backgrounds. Finally, overexpression of slyD causes filamentation of the host. Thus, among the FKBP genes found in organisms across the evolutionary spectrum, slyD is unique in having three distinct drug-independent phenotypes. 相似文献
44.
M. V. Bazunova L. A. Sharafutdinova R. Yu. Lazdin V. V. Chernova D. N. Mixonov V. P. Zakharov 《Applied Biochemistry and Microbiology》2018,54(5):474-477
The conditions to obtain materials with elastic-viscous properties based on chitosan succinamide have been studied. A decreased polymer content and a transition from visco-elastic liquids to elastic-viscous systems were shown upon the addition of glycerol to an aqueous solution of chitosan succinamide. The systemic response, biological compatibility, and dynamics of bioresorbability of the obtained materials were studied during implantation in laboratory animals. 相似文献
45.
46.
Continental‐scale macrofungal assemblage patterns correlate with climate,soil carbon and nitrogen deposition 下载免费PDF全文
47.
48.
49.
50.