全文获取类型
收费全文 | 1923篇 |
免费 | 98篇 |
出版年
2021年 | 12篇 |
2020年 | 11篇 |
2019年 | 15篇 |
2018年 | 31篇 |
2017年 | 16篇 |
2016年 | 29篇 |
2015年 | 54篇 |
2014年 | 53篇 |
2013年 | 191篇 |
2012年 | 101篇 |
2011年 | 106篇 |
2010年 | 79篇 |
2009年 | 59篇 |
2008年 | 84篇 |
2007年 | 89篇 |
2006年 | 88篇 |
2005年 | 83篇 |
2004年 | 89篇 |
2003年 | 73篇 |
2002年 | 94篇 |
2001年 | 44篇 |
2000年 | 40篇 |
1999年 | 31篇 |
1998年 | 31篇 |
1997年 | 28篇 |
1996年 | 22篇 |
1995年 | 31篇 |
1994年 | 25篇 |
1993年 | 21篇 |
1992年 | 21篇 |
1991年 | 20篇 |
1990年 | 35篇 |
1989年 | 16篇 |
1988年 | 18篇 |
1987年 | 14篇 |
1986年 | 22篇 |
1985年 | 23篇 |
1984年 | 17篇 |
1983年 | 20篇 |
1982年 | 13篇 |
1981年 | 16篇 |
1980年 | 13篇 |
1979年 | 15篇 |
1977年 | 11篇 |
1976年 | 14篇 |
1975年 | 11篇 |
1974年 | 18篇 |
1973年 | 12篇 |
1972年 | 8篇 |
1966年 | 8篇 |
排序方式: 共有2021条查询结果,搜索用时 140 毫秒
1.
2.
A new snake-eel,Apterichtus keramanus, is described on the basis of a single 276-mm TL specimen trawled from the coast of Kerama Islands, Okinawa Prefecture, Japan.
The species is unique in the genus in having the posterior nostril opening entirely inside the mouth and a dark band running
from the anteroventral margin of the eye to the upper lip. 相似文献
3.
4.
5.
Masayuki Sasaki Kenji Sugio Jun-Ichi Soejima Tatsuro Ikeuchi Akira Tonomura Takeo Iwama Joji Utsunomiya Takehiko Sasazuki 《Human genetics》1987,77(1):36-39
Summary We investigated possible association of and linkage between HLA and familial polyposis coli (FPC). In 182 individuals from 66 pedigrees of FPC and 108 individuals from a normal population, HLA-A,-B, and-C antigens were determined. When the frequencies of HLA antigens in 66 unrelated patients and in normal controls were compared, no association of FPC with HLA was observed. For the linkage analysis, HLA haplotypes of 17 affected sib pairs were investigated by the affected sib pair method. The number of pairs which shared two, one, and no haplotypes identical by descent was not significantly different from the number expected with random occurrence (P>0.95). Finally, seven families were analyzed using Morton's sequential test. A maximum lod score of-0.056 at a recombination fraction of 0.4, and a lod of-3.089 at a recombination fraction of 0.05 were obtained. Therefore, there is neither an association of nor linkage between FPC and HLA. 相似文献
6.
Extractable nuclear antigens (ENA) were prepared from liver of C57BL/6J mouse and analyzed by SDS PAGE Western-immunoblotting techniques. Some protein components of the ENA, with molecular weights of 94 K, 65 K, 32 K, and 26 K, reacted with antinuclear antibodies in the sera of NOD mice. Incidence of antinuclear antibodies in the sera of NOD mice with aging were measured by ELISA method using the ENA as antigen. The antinuclear antibodies were not detected in young NOD mice (10 weeks old). However, the incidence increased with aging and reached 100% in the female NOD mice of 40 weeks. In the male NOD mice, the incidence of antinuclear antibodies was delayed and low in comparison with that in female. 相似文献
7.
Nuclear protein antigens to the antinuclear antibodies in serum of non-obese diabetic (NOD) mice were investigated. In the serum of diabetic NOD female mice (20 weeks old), the antinuclear antibodies were detected by indirect immunofluorescence assay using frozen sections of liver of C 57 BL/6 J or NOD mice as antigen. Nuclei were separated from the liver of C 57 BL/6 J mice and solubilized. Solubilized nuclear antigens were analyzed by SDS PAGE-Western immunoblotting techniques. Nuclear protein antigens with molecular weights of 26,000, 32,000 and 65,000 showed strongly positive reactions with the antinuclear antibodies in the serum of the NOD mouse. 相似文献
8.
The protein factor which binds to the upstream activating sequence of Saccharomyces cerevisiae ENO1 gene. 总被引:11,自引:2,他引:9 下载免费PDF全文
Using a gel retardation assay it was shown that the 87 bp DNA fragment (UAS87) containing the upstream activating sequence (UAS) of S. cerevisiae EN01 gene and a nuclear extract gave rise to three migration-retarded species specific to UAS87. Heat- or proteinase-treatment of the nuclear extract revealed that these species were protein-DNA complexes. The precise binding region of the protein identified by DNaseI protection analysis was found to include a CCAAACA sequence which forms a dyad-symmetrical structure. The amount of one of the three migration-retarded species significantly increased when cells were grown in medium containing a gluconeogenic carbon source. The introduction of pGCR8, a multicopy plasmid containing GCR1 gene, a regulatory gene controlling the expression of several glycolytic enzymes, showed no effect on the amount of three migration-retarded species. 相似文献
9.
Relationship between susceptibility and immune response to staphylococcal exfoliative toxin A in mammalian species 总被引:2,自引:0,他引:2
Staphylococcal exfoliative toxin A (ETA) had a splitting effect at the granular layer of skin in humans and neonatal mice, but not in rabbits, guinea pigs, golden hamsters, or rats. Besides its splitting effect, ETA could stimulate productions of neutralizing antibody to ETA in rabbits, rats and B10D2 mice, but not in golden hamsters, guinea pigs, or ICR, HRS/J, and C57BL/10 mice. In our epidemiological investigation of human sera, the percentage of antibody to ETA in sera obtained from patients with impetigo (8%) was lower than those in sera of healthy males (23%) and females (29%). The relationship between susceptibility and immune response to ETA in these mammalians could be divided into three groups: the possession of resistant skin and high production of antibody to ETA; the possession of resistant skin and low production of antibody to ETA; the possession of sensitive skin and various titers of antibody to ETA. 相似文献
10.
Nucleotide sequences of Saccharomycopsis fibuligera genes for extracellular beta-glucosidases as expressed in Saccharomyces cerevisiae 总被引:1,自引:0,他引:1
M Machida I Ohtsuki S Fukui I Yamashita 《Applied and environmental microbiology》1988,54(12):3147-3155
We isolated two genes for extracellular beta-glucosidase, BGL1 and BGL2, from the genomic library of the yeast Saccharomycopsis fibuligera. Gene products (BGLI and BGLII) were purified from the culture fluids of Saccharomyces cerevisiae transformed with BGL1 and BGL2, respectively. Molecular weights of BGLI and BGLII were estimated to be 220,000 and 200,000 by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The two beta-glucosidases showed the same enzymatic characteristics, such as thermo-denaturation kinetics and dependencies on pH and temperature, but quite different substrate specificities: BGLI hydrolyzed cellobiose efficiently, but BGLII did not. This result is consistent with the observation that the S. cerevisiae transformant carrying BGL1 fermented cellobiose to ethanol but the transformant carrying BGL2 did not. Southern blot analysis revealed that the two beta-glucosidase genes were derived from Saccharomycopsis fibuligera and that the nucleotide sequences of the two genes are closely related. The complete nucleotide sequences of the two genes were determined. BGL1 and BGL2 encode 876- and 880-amino-acid proteins which were shown to be highly similar to each other. The putative precursors begin with hydrophobic segments that presumably act as signal sequences for secretion. Amino acid analysis of the purified proteins confirmed that BGL1 and BGL2 encode BGLI and BGLII, respectively. 相似文献