全文获取类型
收费全文 | 422676篇 |
免费 | 44002篇 |
国内免费 | 194篇 |
出版年
2016年 | 4598篇 |
2015年 | 6104篇 |
2014年 | 7196篇 |
2013年 | 10798篇 |
2012年 | 11725篇 |
2011年 | 12217篇 |
2010年 | 8288篇 |
2009年 | 7604篇 |
2008年 | 10851篇 |
2007年 | 11515篇 |
2006年 | 10855篇 |
2005年 | 10338篇 |
2004年 | 10424篇 |
2003年 | 10204篇 |
2002年 | 9962篇 |
2001年 | 17479篇 |
2000年 | 17490篇 |
1999年 | 14061篇 |
1998年 | 4878篇 |
1997年 | 5207篇 |
1996年 | 4909篇 |
1995年 | 4786篇 |
1994年 | 4682篇 |
1993年 | 4692篇 |
1992年 | 12343篇 |
1991年 | 12152篇 |
1990年 | 12128篇 |
1989年 | 11909篇 |
1988年 | 11227篇 |
1987年 | 10548篇 |
1986年 | 9855篇 |
1985年 | 10283篇 |
1984年 | 8471篇 |
1983年 | 7319篇 |
1982年 | 5657篇 |
1981年 | 5058篇 |
1980年 | 4713篇 |
1979年 | 8113篇 |
1978年 | 6337篇 |
1977年 | 5960篇 |
1976年 | 5695篇 |
1975年 | 6153篇 |
1974年 | 6727篇 |
1973年 | 6592篇 |
1972年 | 6149篇 |
1971年 | 5557篇 |
1970年 | 4789篇 |
1969年 | 4796篇 |
1968年 | 4463篇 |
1967年 | 3820篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
A series of site-directed mutations has been constructed in E coli 16S rRNA and shown to suppress UGA-dependent translational termination. With the exception of the C726 to G base change, all were constructed in helix 34. Characterization of these mutations is reviewed here and from these data and mRNA-rRNA base pairing model for the termination event is presented. The interaction functions via antiparallel base pairing between either 1 of the 2 UCA motifs in helix 34 and the complementary UGA stop codon on the message, thus forming a quasicontinuous A-type helical structure that is further stabilized by stacking enthalpy. Finally, rRNA motifs potentially required for UAA and UAG-dependent translational termination are discussed. 相似文献
62.
E. R. R. Rochedo L. F. C. Conti H. G. Paretzke 《Radiation and environmental biophysics》1996,35(4):243-261
The structure and mathematical model of PARATI, a detailed computer programme developed for the assessment of the radiological
consequences of an accidental contamination of urban areas, is described with respect to the scenarios used for the estimation
of exposure fields in a village or town, the models for the initial and secondary contamination with the radionuclide 137Cs, the concepts for calculating the resulting radiation exposures and the changes with time of the contamination and radiation
fields. Kerma rates at various locations in tropical urban areas are given, and the contribution of different contaminated
surfaces to these rates after dry or wet deposition are discussed.
Received: 12 April 1996 / Accepted in revised form: 30 August 1996 相似文献
63.
M G Lee 《Molecular and cellular biology》1996,16(3):1220-1230
64.
65.
66.
The cold-shock response — a hot topic 总被引:4,自引:2,他引:2
67.
68.
C. M. Hooijmans T. A. Abdin G. J. Alaerts 《Applied microbiology and biotechnology》1995,43(5):781-785
Lipid phosphate, which is a measure of viable biomass, was determined using biofilm samples from three different laboratory-scale
reactors. The analysis procedure proposed in the literature was modified and tested for suitability in experiments with biofilm
reactors. The microbial contents of the biofilms studied are compared in three types of reactor.
Received: 2 November 1994/Accepted: 23 January 1995 相似文献
69.
The content of proteins, lipids and carbohydrates and the calorific contents in six Antarctic and three south Chilean brown algae were determined. These constitute the first reports of chemical composition in the endemic Antarctic species Cystosphaera jacquinotii, Phaeurus antarcticus and Desmarestia antarctica. There were no marked differences in total energy levels between Antarctic and cold-temperate species (values between 10.6 and 13 kJ g–1 dry weight). However, species such as Adenocystis utricularis showed significantly higher ash-free energy (26.3 kJ), which is explained in terms of morpho-functional differentiation. Ascoseira mirabilis and Phaeurus antarcticus showed high total lipids (2.1–2.2% dry weight) and soluble carbohydrates (5.9 and 3.4% dry weight). In general, algae from Chile had similar energy levels and no obvious differences in organic content could be found. 相似文献
70.