全文获取类型
收费全文 | 233426篇 |
免费 | 16122篇 |
国内免费 | 47篇 |
出版年
2021年 | 1912篇 |
2018年 | 3243篇 |
2017年 | 3123篇 |
2016年 | 3828篇 |
2015年 | 3477篇 |
2014年 | 4737篇 |
2013年 | 6735篇 |
2012年 | 8017篇 |
2011年 | 8517篇 |
2010年 | 6043篇 |
2009年 | 5166篇 |
2008年 | 7629篇 |
2007年 | 7852篇 |
2006年 | 7564篇 |
2005年 | 7016篇 |
2004年 | 7175篇 |
2003年 | 6875篇 |
2002年 | 6819篇 |
2001年 | 9517篇 |
2000年 | 9181篇 |
1999年 | 7185篇 |
1998年 | 2252篇 |
1997年 | 2061篇 |
1996年 | 1936篇 |
1992年 | 5639篇 |
1991年 | 5879篇 |
1990年 | 5856篇 |
1989年 | 5782篇 |
1988年 | 5377篇 |
1987年 | 5026篇 |
1986年 | 4601篇 |
1985年 | 4827篇 |
1984年 | 3816篇 |
1983年 | 3136篇 |
1982年 | 2116篇 |
1981年 | 1827篇 |
1980年 | 1834篇 |
1979年 | 3451篇 |
1978年 | 2674篇 |
1977年 | 2463篇 |
1976年 | 2408篇 |
1975年 | 2897篇 |
1974年 | 3213篇 |
1973年 | 3190篇 |
1972年 | 2846篇 |
1971年 | 2694篇 |
1970年 | 2262篇 |
1969年 | 2226篇 |
1968年 | 2089篇 |
1967年 | 1858篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
11.
V V Sviridov E V Kozhevnikova 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1985,(9):67-70
The immunization of mice with the protein fraction of B. pertussis strain 305 has made it possible to obtain hybridomas producing monoclonal antibodies to B. pertussis antigens. Ascitic fluids containing monoclonal antibodies react in the ELISA in high titers and actively agglutinate B. pertussis strains 305 and 475. 相似文献
12.
A A Sukhopiatkina O S Bat A V Levitskaia V G Potapova 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1985,(4):80-81
The study of the specific epidemiological and clinical features of Q fever revealed the existence of an active focus of infection among humans due to their contacts with agricultural animals in one of the districts of the region. The focus was manifested by group morbidity among the cattle-tending personnel of a dairy farm. The source of this infection was cattle. The infection was transferred mainly through the air. The disease took a moderately severe course. The study of the rickettsial contamination of humans, animals and ticks suggested the presence of the active epidemic process and made it possible to work out concrete antiepidemic measures. 相似文献
13.
14.
F F Dias M K Shaikh Y B Bhatt D C Modi V R Subramanyam 《The Journal of applied bacteriology》1986,60(4):271-275
Mutants of Bacillus amyloliquefaciens resistant to at least 10 micrograms/ml of tunicamycin were isolated and shown to be pleiotropic. The mutants were more resistant to streptomycin, chloramphenicol, kanamycin and neomycin than was the parent strain but less resistant to penicillin G and tetracycline. They were more autolytic, presumably due to an altered cell wall. The mutants produced reduced levels of amylase, penicillinase and both metal and serine protease besides having an enhanced sporulation frequency and being more motile. 相似文献
15.
V A Berezin E N Zhmarev I A Brodskaia G M Shevchenko L S Zashko 《Biulleten' eksperimental'no? biologii i meditsiny》1985,100(7):68-70
The content of neurospecific proteins S-100, GFA and D2 was measured in malignant cerebral tumors by electrophoresis with the use of monospecific antisera. Concomitant measurement of proteins S-100 and GFA is a more reliable diagnostic criterion as to the tumor histogenesis than study of each protein alone. D2 protein appeared to be the most stable specific marker. 相似文献
16.
The role of DNA sequence in determining nucleosome positions in vivo was investigated by comparing the positions adopted by nucleosomes reconstituted on a yeast plasmid in vitro using purified core histones with those in native chromatin containing the same DNA, described previously. Nucleosomes were reconstituted on a 2.5 kilobase pair DNA sequence containing the yeast TRP1ARS1 plasmid with CUP1 as an insert (TAC-DNA). Multiple, alternative, overlapping nucleosome positions were mapped on TAC-DNA. For the 58 positioned nucleosomes identified, the relative positioning strengths and the stabilities to salt and temperature were determined. These positions were, with a few exceptions, identical to those observed in native, remodeled TAC chromatin containing an activated CUP1 gene. Only some of these positions are utilized in native, unremodeled chromatin. These observations suggest that DNA sequence is likely to play a very important role in positioning nucleosomes in vivo. We suggest that events occurring in yeast CUP1 chromatin determine which positions are occupied in vivo and when they are occupied. 相似文献
17.
18.
19.
20.
T. B. Lapirova V. R. Mikryakova A. S. Mavrin G. A. Yinogradova 《Journal of Evolutionary Biochemistry and Physiology》2000,36(1):47-51
The paper presents data on a change in lysozyme content in tissues of spleen, liver and heart in fry of the Lena River sturgeon
exposed to the presence of sublethal concentrations of Hg2+, Cd2+, and Cu2+ under conditions of chronic experiment. It has been shown that the lysozyme content in fish tissues varies and has a phasic
character. The amplitude of fluctuations of this parameter depends on the moment of sampling, nature of the toxicant, and
structural-functional organization of the studied organs. 相似文献