全文获取类型
收费全文 | 616110篇 |
免费 | 61860篇 |
国内免费 | 447篇 |
专业分类
678417篇 |
出版年
2018年 | 5570篇 |
2016年 | 7252篇 |
2015年 | 8990篇 |
2014年 | 10834篇 |
2013年 | 16016篇 |
2012年 | 17390篇 |
2011年 | 18330篇 |
2010年 | 12464篇 |
2009年 | 11359篇 |
2008年 | 16192篇 |
2007年 | 16984篇 |
2006年 | 16005篇 |
2005年 | 15340篇 |
2004年 | 15229篇 |
2003年 | 14840篇 |
2002年 | 14632篇 |
2001年 | 26671篇 |
2000年 | 26778篇 |
1999年 | 21156篇 |
1998年 | 7136篇 |
1997年 | 7497篇 |
1996年 | 7167篇 |
1995年 | 6720篇 |
1994年 | 6629篇 |
1993年 | 6513篇 |
1992年 | 17881篇 |
1991年 | 17539篇 |
1990年 | 17578篇 |
1989年 | 17170篇 |
1988年 | 16132篇 |
1987年 | 15290篇 |
1986年 | 14025篇 |
1985年 | 14662篇 |
1984年 | 11943篇 |
1983年 | 10319篇 |
1982年 | 7768篇 |
1981年 | 7016篇 |
1980年 | 6546篇 |
1979年 | 11416篇 |
1978年 | 8831篇 |
1977年 | 8312篇 |
1976年 | 7948篇 |
1975年 | 8809篇 |
1974年 | 9557篇 |
1973年 | 9437篇 |
1972年 | 8580篇 |
1971年 | 7884篇 |
1970年 | 6908篇 |
1969年 | 6687篇 |
1968年 | 6267篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
221.
E. Molina Grima J. A. Sánchez Pérez F. García Camacho F. G. Acién Fernández J. M. Fernández Sevilla F. Valdés Sanz 《Biotechnology letters》1994,16(10):1035-1040
Summary Eicosapentaenoic acid (EPA) volumetric productivity from an outdoor chemostat culture ofPhaeodactylum tricornutum UTEX 640 in a 50-l tubular photobioreactor varies with dilution rate, reaching a maximum of 47.8 mg l–1 d–1 at D=0.36 d–1. Continuous culture at high dilution rates' is proposed as the most adequate operating mode to maximize polyunsaturated fatty acid production. 相似文献
222.
G A Vilkov E M Stepanenko T A Khoruzhaia 《Biulleten' eksperimental'no? biologii i meditsiny》1985,99(1):48-50
The authors studies the effects of blood serum and IgG fraction from dogs immunized with brain and blood sera from patients with multiple sclerosis and schizophrenia on lipid peroxidation in rat brain homogenates. Measured the content of diene conjugates (DC) and malonic dialdehyde (MDA) in the rat brain after administering the IgG fraction. It was established that antioxidant activity of blood sera and IgG fraction from control animals and donors was significantly higher as compared to experimental. Administration of the IgG fraction brought about an increase in the content of DC and MDA in the brain of experimental animals. It is concluded that complement-dependent brain antibodies present in the blood serum of patients with schizophrenia and multiple sclerosis potentiate lipid peroxidation in the cerebral tissue and that the unsophisticated and informative method for antibody determination may be used in clinical practice. 相似文献
223.
224.
Cloning and mapping of the chloroplast DNA sequences for two messenger RNAs from mustard (Sinapis alba L.). 总被引:7,自引:3,他引:4 下载免费PDF全文
G Link 《Nucleic acids research》1981,9(15):3681-3694
225.
226.
227.
A Rauch R A Pfeiffer G Leipold H Singer M Tigges M Hofbeck 《American journal of human genetics》1999,64(2):659-666
228.
Microsatellite DNA in peach (Prunus persica L. Batsch) and its use in fingerprinting and testing the genetic origin of cultivars. 总被引:11,自引:0,他引:11
R Testolin T Marrazzo G Cipriani R Quarta I Verde M T Dettori M Pancaldi S Sansavini 《Génome》2000,43(3):512-520
We isolated and sequenced 26 microsatellites from two genomic libraries of peach cultivar 'Redhaven', enriched for AC/GT and AG/CT repeats, respectively. For 17 of these microsatellites, it was possible to demonstrate Mendelian inheritance. Microsatellite polymorphism was assayed in 50 peach and nectarine cultivars. Of the 1300 PCRs carried out, all but two produced amplified products of the expected size. All microsatellites were polymorphic, showing 2-8 alleles per locus. Heterozygosity ranged from 0.04-0.74 (mean 0.47); the discrimination power (PD) ranged from 0.04-0.84 (mean 0.60). Cultivar heterozygosity varied greatly, with one cultivar ('Independence') being homozygous at all loci. The set of microsatellites discriminated all cultivars investigated, except several sport mutations, i.e., 'Dixitime' vs. 'Springcrest', 'Compact Redhaven' vs. 'Redhaven', and two pairs of cultivars, 'Venus' vs. 'Orion' and 'Elegant Lady' vs. 'Rome Star', whose pedigrees are controversial. We were able to analyze the paternity of several cultivars. In most cases, the parenthood was confirmed. The comparison of three long-living 'Redhaven' accessions supplied by different repositories did not provide any evidence of somatic instability of microsatellites. Hence, microsatellites, ranked according to their information content, are recommended as markers of choice for peach fingerprinting and suggestions are provided for interpreting band profiles and the correct sizing of alleles. 相似文献
229.
Ia I Serkiz A I Lipskaia L B Pinchuk V V Trishin Iu F Kataevski? G N Koval' 《Radiobiologiia》1991,31(5):629-634
Irradiation conditions in which laboratory animals were kept in experimental laboratories of Chernobyl and Kiev after the accident at the Chernobyl A.P.S. are described. The data are presented on the spectral structural and activity of radionuclides in the diet as well as in the organs and tissues of the animals. The radiation loads have been estimated with regard to an external gamma component and the internal one contributed by the incorporated radionuclides. It has been shown that radiation doses received by the animals during their lifetime due to these contributions do not exceed units of cGy. 相似文献
230.