全文获取类型
收费全文 | 912809篇 |
免费 | 91877篇 |
国内免费 | 694篇 |
出版年
2018年 | 12438篇 |
2017年 | 12000篇 |
2016年 | 14087篇 |
2015年 | 14716篇 |
2014年 | 17426篇 |
2013年 | 24911篇 |
2012年 | 29483篇 |
2011年 | 33496篇 |
2010年 | 23399篇 |
2009年 | 21972篇 |
2008年 | 29395篇 |
2007年 | 31471篇 |
2006年 | 24996篇 |
2005年 | 24437篇 |
2004年 | 24043篇 |
2003年 | 23469篇 |
2002年 | 22947篇 |
2001年 | 41505篇 |
2000年 | 40869篇 |
1999年 | 32565篇 |
1998年 | 11321篇 |
1997年 | 11573篇 |
1996年 | 10953篇 |
1995年 | 10047篇 |
1994年 | 9619篇 |
1993年 | 9672篇 |
1992年 | 25876篇 |
1991年 | 25229篇 |
1990年 | 24349篇 |
1989年 | 23879篇 |
1988年 | 21869篇 |
1987年 | 20685篇 |
1986年 | 19210篇 |
1985年 | 18980篇 |
1984年 | 15460篇 |
1983年 | 13531篇 |
1982年 | 10190篇 |
1981年 | 9108篇 |
1980年 | 8453篇 |
1979年 | 14287篇 |
1978年 | 11259篇 |
1977年 | 10123篇 |
1976年 | 9615篇 |
1975年 | 10731篇 |
1974年 | 11416篇 |
1973年 | 11281篇 |
1972年 | 10743篇 |
1971年 | 9608篇 |
1970年 | 8061篇 |
1969年 | 7854篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
201.
202.
L-myo-Inositol-1-phosphate synthase has been found to have at least a 5-fold preference for the beta-anomer of its natural substrate D-Glc-6-P. The alpha-anomer appears to be an inhibitor of the reaction and may be converted to product as well. As well as showing an enzymatic preference for the equatorial C-1 hydroxyl of D-Glc-6-P, our results suggest that it is the pyranose form of D-Glc-6-P that binds to the enzyme and that ring-opening is an enzymatic step. We have also found D-2-dGlc-6-P, D-2-F-2-dGlc-6-P, and D-Man-6-P each to be both competitive inhibitors and substrates that are converted to inositol phosphates by the synthase. D-Allose-6-P is a weak inhibitor of the enzyme, but not a substrate. D-Gal-6-P is neither substrate nor inhibitor. Thus the specificity of the synthase with respect to single position epimers of D-Glc-6-P increases in the order C1 less than C2 much less than C3 less than C4. 相似文献
203.
A L Nevmiatullin O N Vorob'eva A N Maianski? 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1985,(7):67-71
The neutrophil-stimulating properties of 38 S. aureus strains and 32 S. epidermidis strains were studied in the reaction of luminol-mediated chemiluminescence. All S. aureus strains and 29 S. epidermidis strains were found to possess neutrophil-stimulating activity, the mean activity index for S. aureus being significantly higher. The stimulating activity of the strains varied within a wide range (the variation coefficient was 120.0 +/- 21.9%) and did not correlate with the content of protein A in bacterial cells and the degree of their hydrophoby. The opsonization of staphylococci with normal human serum enhanced the neutrophil reaction 1.5- to 100-fold and simultaneously leveled out the chemiluminescence indices in experiments with different strains (the variation coefficient was 8.0 +/- 1.5%). The nature of the neutrophil-stimulating effect of staphylococci and its relationship to the exploratory reactions of phagocytes are discussed. 相似文献
204.
Cryptococcosis is an often fatal opportunistic fungal infection. Despite efforts to elucidate the role of immunity in host defense against the disease, much remains to be learned. The purpose of this brief review is to provide the reader with an overview of the history of research concerned with host immunity in cryptococcosis. Both humoral and cell-mediated studies are included. An effort has been made to present the reader with a comprehensive list of references in the hope of encouraging additional reading and research in this important area. 相似文献
205.
B Spyropoulos P B Moens J Davidson J A Lowden 《American journal of human genetics》1981,33(3):375-380
Chi-square analyses of new data as well as data previously reported by Myrianthopoulos have shown that grandparents of Tay-Sachs carriers die from proportionally the same causes as grandparents of noncarriers. It is unlikely that there is any advantage to being a Tay-Sachs carrier insofar as resistance to tuberculosis is concerned. Our results are further evidence to support Fraikor's claim that the high carrier frequency of the allele in Ashkenazi Jews is probably caused by a combination of founder effect, genetic drift, and differential immigration patterns. 相似文献
206.
207.
208.
209.
210.