全文获取类型
收费全文 | 14374篇 |
免费 | 1074篇 |
国内免费 | 12篇 |
出版年
2023年 | 70篇 |
2022年 | 84篇 |
2021年 | 257篇 |
2020年 | 156篇 |
2019年 | 210篇 |
2018年 | 390篇 |
2017年 | 359篇 |
2016年 | 460篇 |
2015年 | 600篇 |
2014年 | 729篇 |
2013年 | 1031篇 |
2012年 | 1184篇 |
2011年 | 1199篇 |
2010年 | 781篇 |
2009年 | 583篇 |
2008年 | 795篇 |
2007年 | 723篇 |
2006年 | 686篇 |
2005年 | 581篇 |
2004年 | 530篇 |
2003年 | 484篇 |
2002年 | 476篇 |
2001年 | 142篇 |
2000年 | 108篇 |
1999年 | 142篇 |
1998年 | 165篇 |
1997年 | 117篇 |
1996年 | 107篇 |
1995年 | 92篇 |
1994年 | 100篇 |
1993年 | 79篇 |
1992年 | 81篇 |
1991年 | 100篇 |
1990年 | 69篇 |
1989年 | 59篇 |
1988年 | 78篇 |
1987年 | 69篇 |
1986年 | 59篇 |
1985年 | 79篇 |
1984年 | 77篇 |
1983年 | 76篇 |
1982年 | 87篇 |
1981年 | 89篇 |
1980年 | 76篇 |
1979年 | 77篇 |
1978年 | 62篇 |
1975年 | 59篇 |
1974年 | 68篇 |
1972年 | 66篇 |
1969年 | 55篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Formation of protoplasts and their reversion were followed in 7 strains of brevibacteria. The formation of protoplasts and
their reversion differed both between various species of brevibacteria and between various mutant strains of the same species. 相似文献
93.
Reversibility of the respiration-deficient locuspet23 and auxotrophic locuslys2 was followed in the standard (RAD1) and UV sensitive (rad1–2) strains ofSaccharomyces cerevisiae, both after identical doses of UV radiation and at identical survival. When comparing the reversibility after the treatment
with identical doses of UV radiation a much higher reversibility of both loci in strainrad1–2 could be detected. When comparing the reversibility of the loci in question at identical survival of both strains it could
be found that the reversibility of thepet23 locus is again much higher in strainrad1–2, whereas the reversibility of thelys2 locus is roughly identical in the two strains. Thus, the function of geneRAD1 in repair processes is apparently associated with the “error-free” repair, both at low and high doses of ultraviolet radiation. 相似文献
94.
Sandra Casellato 《Hydrobiologia》1984,115(1):65-69
Data on the life-cycle of a population of Branchiura sowerbyi Beddard in a water-lily tank at the Botanical Garden in Padua are reported. The breeding period is from April to July, after which the reproductive system is partially resorbed (August–September) and reformed later in the autumn. The karyology of the species was also studied, and revealed 38 mitotic chromosomes in the gonia, and 19 bivalents in the primary spermatocytes and in the primary oocytes. 相似文献
95.
Glucose inhibits the inducible synthesis of β-D-glucosidase inStreptomyces granaticolor. Neither cAMP nor cGMP influence the inhibitory effect of glucose. Glucose also inhibits the inducible synthesis of the cellobiose
uptake system but has no effect on its activity. This may be the mechanism underlying glucose inhibition of induction of β-D-glucosidase inS.granaticolor. 相似文献
96.
97.
M. Kučera 《Journal of invertebrate pathology》1984,43(2):190-196
Gel permeation, preparative isoelectric focusing, and affinity chromatography were used to purify three inhibitors of proteolytic activity from perchloric acid extracts of last instar Galleria mellonella larvae. Electrofocusing experiments revealed three isoinhibitors with different isoelectric points: inhibitor I-1 with p1 of pH 5.6, inhibitor I-2, pH 7.7, and inhibitor I-3 (of small inhibitory activity), pH 8.6. By affinity chromatography on trypsin-Sepharose 4B the I-1 was purified 9.7 ×, but 71.1% of inhibitory activity was lost. Molecular mass of the inhibitory complex was 12,600 Da. I-1 and I-2 are relatively stable to heat at several pHs with minor stability at pH 10. I-1 and I-2 inhibit serine proteases about 2.5 times as much as sulfhydryl proteases. In the same ratio protease P-1 and protease P-2 from Metarhizium anisopliae are inhibited. 相似文献
98.
99.
The contribution deals with the phytocenological analysis of theRondeletio correifoliae-Andropogonetum multinervosi, an endemic savanna association occuring on the Siguanea Hills (Sierra de la Siguanea) near the Colony Hotel. 相似文献
100.
Sandra N. Hing Carolyn M. Giles Angela H. L. Fielder J. Richard Batchelor 《Immunogenetics》1986,23(3):151-155
Twenty-three individuals from various disease groups and normal controls were identified by immunofixation with anti-C4, C4-dependent lysis, determination of Rg (Rodgers) and Ch (Chido) phenotypes, and immunoblotting with C4-specific mouse monoclonal antibody. We found that one haplotype predominates with the C4B
*
5 allele, HLA-A11, B22(55), Cw3, Bf
*
S, C4A
*
4B
*
5, which also carries the Ch
1,–2, 3 haplotype. The B5 allotype was also found with HLA-1360, HLA-1335 in Caucasoids, and HLA-B18 in non-Caucasoids; these carried the Ch
–1, –2, –3 haplotype. Our results are in accord with an earlier report of two B5 subtypes, B5Rg+ and B5Rg– (Roos et al. 1984). The specificity of the mouse monoclonal antibodies IC4 and 21312 had been previously related to C4A and C4B, respectively, but our results suggest that they relate more closely to Rg and Ch determinants. 相似文献