全文获取类型
收费全文 | 1483篇 |
免费 | 127篇 |
专业分类
1610篇 |
出版年
2021年 | 22篇 |
2018年 | 22篇 |
2017年 | 16篇 |
2016年 | 27篇 |
2015年 | 39篇 |
2014年 | 48篇 |
2013年 | 68篇 |
2012年 | 62篇 |
2011年 | 68篇 |
2010年 | 42篇 |
2009年 | 36篇 |
2008年 | 40篇 |
2007年 | 40篇 |
2006年 | 42篇 |
2005年 | 42篇 |
2004年 | 43篇 |
2003年 | 41篇 |
2002年 | 34篇 |
2001年 | 49篇 |
2000年 | 50篇 |
1999年 | 42篇 |
1998年 | 22篇 |
1996年 | 13篇 |
1994年 | 13篇 |
1993年 | 15篇 |
1992年 | 29篇 |
1991年 | 24篇 |
1990年 | 28篇 |
1989年 | 22篇 |
1988年 | 37篇 |
1987年 | 29篇 |
1986年 | 13篇 |
1985年 | 35篇 |
1984年 | 15篇 |
1983年 | 29篇 |
1982年 | 23篇 |
1981年 | 25篇 |
1980年 | 14篇 |
1979年 | 29篇 |
1978年 | 20篇 |
1977年 | 17篇 |
1976年 | 13篇 |
1975年 | 17篇 |
1974年 | 21篇 |
1973年 | 17篇 |
1972年 | 18篇 |
1970年 | 16篇 |
1968年 | 14篇 |
1966年 | 13篇 |
1964年 | 12篇 |
排序方式: 共有1610条查询结果,搜索用时 15 毫秒
1.
2.
The destruction of spores of Bacillus subtilis by the combined effects of hydrogen peroxide and ultraviolet light 总被引:3,自引:0,他引:3
W.M. Waites S.E. Harding D.R. Fowler S.H. Jones D. Shaw M. Martin 《Letters in applied microbiology》1988,7(5):139-140
Ultraviolet light irradiation of bacterial spores in the presence of hydrogen peroxide has been shown to produce synergistic kills when compared with ultraviolet light (u.v.) and hydrogen peroxide used sequentially. This use in combination has been patented for the commercial sterilization of packaging before filling with UHT-processed products. Previous results have shown that lamps producing u.v. light with a maximum output at about 254 nm were extremely effective. Results obtained using a Synchrotron radiation source to produce a narrow band of irradiation now shows that the greatest kill of spores of Bacillus subtilis in the presence of hydrogen peroxide is obtained with radiation at ˜270 nm. Such results suggest that the action of the u.v. light is not directly on the spore DNA but may be related to the production of free hydroxyl radicals from hydrogen peroxide. 相似文献
3.
4.
Structure of the peptidogylcan of bacterial cell walls. I 总被引:11,自引:0,他引:11
5.
6.
Carroll D. Arnett Joanna S. Fowler Robert R. MacGregor David J. Schlyer Alfred P. Wolf Bengt Långström Christer Halldin 《Journal of neurochemistry》1987,49(2):522-527
The distribution of carbon-11-labeled L-deprenyl, an irreversible inhibitor of monoamine oxidase type B (MAO-B), was determined in the baboon brain by positron emission tomography. The irreversible blood-to-brain transfer constant (influx constant, Ki) was measured using a complete metabolite-corrected arterial plasma concentration curve. This influx constant was used as a measure of functional enzyme activity for sequential determinations of MAO-B recovery following a single high dose of unlabeled l -deprenyl. The half-life for turnover of MAO-B was thus determined to be 30 days. Using appropriate irreversible inhibitors, this procedure should be generally useful for determining enzyme turnover rates in any organ in vivo and can be applied to some human studies as well. 相似文献
7.
8.
A study is described in which three general practices were provided with low cost, low technology support from a "facilitator" and were compared with control practices in the ascertainment of major risk factors for cardiovascular disease in middle aged patients. Patients who were attending for a consultation with their general practitioners were recruited to make an appointment with a practice nurse for a health check, and this was compared with ordinary consultations in the control practices. Practices were helped by the facilitator to develop the nurse''s role. During the study the increase between intervention and control practices in blood pressure recording was doubled and in the recording of smoking habit it was quadrupled, and there was a fivefold increase in the recording of weight. This model can be applied to other aspects of prevention and general practice care. 相似文献
9.
Specificity of endoproteinase Asp-N (Pseudomonas fragi): cleavage at glutamyl residues in two proteins 总被引:2,自引:0,他引:2
D Ingrosso A V Fowler J Bleibaum S Clarke 《Biochemical and biophysical research communications》1989,162(3):1528-1534
Endoproteinase Asp-N, a metalloprotease from a mutant strain of Pseudomonas fragi, has been reported to specifically cleave on the N-terminal side of aspartyl and cysteic acid residues. We utilized this enzyme to generate fragments for determining the amino acid sequence of the D-aspartyl/L-isoaspartyl methyltransferase isozyme I from human erythrocytes. Surprisingly, we identified cleavage sites for this enzyme at the N-terminal side of several glutamyl residues in addition to the expected cleavage sites at aspartyl residues. The ability of this enzyme to cleave polypeptides at both glutamyl and aspartyl residues was confirmed by mapping additional sites on erythrocyte carbonic anhydrase I. These results indicate that a more appropriate name for this enzyme may be Endoproteinase Asp/Glu-N. 相似文献
10.
Carrier-free 203Pb has been used to label high affinity lead-binding proteins in rat brain cytosol to allow their initial characterization. The low molecular weight 203Pb-protein complex collected from a Sephadex G-75 column eluate has been further purified by Sephadex DEAE chromatography and then partially characterized. The protein has a molecular weight of 23,000 daltons as determined by SDS polyacrylamide gel electrophoresis and significant levels of glutamic acid (9.3%), aspartic acid (10.8%) and cysteine (9.4%). Western blot studies conducted using the polyclonal antibody to the renal lead-binding proteins showed a lack of reactivity, indicating that the brain protein is immunologically distinct from that found in the kidney. 相似文献