全文获取类型
收费全文 | 2635篇 |
免费 | 210篇 |
国内免费 | 1篇 |
出版年
2023年 | 13篇 |
2022年 | 15篇 |
2021年 | 52篇 |
2020年 | 34篇 |
2019年 | 41篇 |
2018年 | 71篇 |
2017年 | 53篇 |
2016年 | 85篇 |
2015年 | 132篇 |
2014年 | 147篇 |
2013年 | 179篇 |
2012年 | 200篇 |
2011年 | 184篇 |
2010年 | 133篇 |
2009年 | 126篇 |
2008年 | 150篇 |
2007年 | 149篇 |
2006年 | 114篇 |
2005年 | 111篇 |
2004年 | 110篇 |
2003年 | 122篇 |
2002年 | 74篇 |
2001年 | 34篇 |
2000年 | 25篇 |
1999年 | 19篇 |
1998年 | 19篇 |
1997年 | 19篇 |
1995年 | 10篇 |
1992年 | 11篇 |
1991年 | 11篇 |
1989年 | 9篇 |
1988年 | 13篇 |
1987年 | 14篇 |
1986年 | 8篇 |
1985年 | 10篇 |
1984年 | 12篇 |
1983年 | 11篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 13篇 |
1979年 | 12篇 |
1978年 | 11篇 |
1977年 | 8篇 |
1976年 | 11篇 |
1974年 | 12篇 |
1973年 | 12篇 |
1971年 | 10篇 |
1969年 | 8篇 |
1965年 | 8篇 |
1927年 | 7篇 |
排序方式: 共有2846条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
M Nicol C Massart N Savouré 《Comptes rendus des séances de la Société de biologie et de ses filiales》1980,174(1):33-39
The stabilization by glycerol of the serum estradiol 17 beta dehydrogenase has been investigated here in terms of time and temperature. The protected enzyme is stable for a month at least at --20 degrees C. Its activity reaches a maximum at 60 degrees C. In another connection, effect of reduced glutathione, of N. acetyl-cysteine and of various mineral ions on the enzymic conversion has been studied. 相似文献
6.
Elia Pintus Silvia Sorbolini Andrea Albera Giustino Gaspa Corrado Dimauro Roberto Steri Gabriele Marras Nicolò P. P. Macciotta 《Animal genetics》2014,45(1):1-11
Selection is the major force affecting local levels of genetic variation in species. The availability of dense marker maps offers new opportunities for a detailed understanding of genetic diversity distribution across the animal genome. Over the last 50 years, cattle breeds have been subjected to intense artificial selection. Consequently, regions controlling traits of economic importance are expected to exhibit selection signatures. The fixation index (Fst) is an estimate of population differentiation, based on genetic polymorphism data, and it is calculated using the relationship between inbreeding and heterozygosity. In the present study, locally weighted scatterplot smoothing (LOWESS) regression and a control chart approach were used to investigate selection signatures in two cattle breeds with different production aptitudes (dairy and beef). Fst was calculated for 42 514 SNP marker loci distributed across the genome in 749 Italian Brown and 364 Piedmontese bulls. The statistical significance of Fst values was assessed using a control chart. The LOWESS technique was efficient in removing noise from the raw data and was able to highlight selection signatures in chromosomes known to harbour genes affecting dairy and beef traits. Examples include the peaks detected for BTA2 in the region where the myostatin gene is located and for BTA6 in the region harbouring the ABCG2 locus. Moreover, several loci not previously reported in cattle studies were detected. 相似文献
7.
8.
Kazimierz S. Kasprzak Michael P. Waalkes Lionel A. Poirier 《Biological trace element research》1987,13(1):253-273
Interactions between the physiologically essential metals calcium, magnesium, and zinc and the carcinogenic metals nickel
and cadmium were investigated to help elucidate the mechanisms of action of the carcinogenic metals. Bioassay studies revealed
several significant findings, including: (1) the ability of magnesium and calcium to inhibit nickel-induced elevation of pulmonary
adenoma incidence in strain A mice; (2) the ability of magnesium, but not of calcium, to prevent cadmium-induced subcutaneous
sarcoma formation; and (3) the ability of magnesium, but not of calcium, to inhibit nickel-induced muscle tumor formation.
Biochemical studies indicated a direct relationship between the antitumorigenic potential of magnesium and the capacity of
this metal to: (1) inhibit nickel and cadmium uptake by the target tissues in vivo; (2) inhibit nickel-induced disturbances
in DNA synthesis in vivo; (3) inhibit nuclear and cytosolic uptake of nickel by the target tissue cells in vivo; and (4) inhibit
nickel and cadmium binding to DNA in vitro. Calcium, which in most cases did not prevent carcinogenesis, had no consistent
influence on the uptake of carcinogenic metals or their biochemical effects in the target tissues. Magnesium and zinc, but
not calcium, were also found to attenuate the acute toxic effects of nickel, indicating a possible correlation between prevention
of acute effects and reduction in tumorigenicity. Zinc, which antagonizes cadmium tumorigenicity in the rat testis, was found
to reduce markedly cadmium uptake into isolated testicular interstitial cells. Also, zinc was found to inhibit strongly cadmium
binding to DNA in vitro. 相似文献
9.
10.