全文获取类型
收费全文 | 3639篇 |
免费 | 202篇 |
国内免费 | 7篇 |
出版年
2021年 | 18篇 |
2019年 | 19篇 |
2018年 | 28篇 |
2017年 | 24篇 |
2016年 | 42篇 |
2015年 | 55篇 |
2014年 | 67篇 |
2013年 | 249篇 |
2012年 | 156篇 |
2011年 | 197篇 |
2010年 | 124篇 |
2009年 | 129篇 |
2008年 | 214篇 |
2007年 | 197篇 |
2006年 | 198篇 |
2005年 | 203篇 |
2004年 | 216篇 |
2003年 | 224篇 |
2002年 | 237篇 |
2001年 | 66篇 |
2000年 | 59篇 |
1999年 | 79篇 |
1998年 | 61篇 |
1997年 | 48篇 |
1996年 | 41篇 |
1995年 | 38篇 |
1994年 | 37篇 |
1993年 | 51篇 |
1992年 | 65篇 |
1991年 | 53篇 |
1990年 | 54篇 |
1989年 | 44篇 |
1988年 | 47篇 |
1987年 | 27篇 |
1986年 | 53篇 |
1985年 | 30篇 |
1984年 | 29篇 |
1983年 | 27篇 |
1982年 | 26篇 |
1981年 | 30篇 |
1980年 | 28篇 |
1979年 | 33篇 |
1978年 | 18篇 |
1977年 | 19篇 |
1976年 | 25篇 |
1975年 | 22篇 |
1974年 | 22篇 |
1973年 | 16篇 |
1971年 | 15篇 |
1969年 | 13篇 |
排序方式: 共有3848条查询结果,搜索用时 265 毫秒
1.
Kaori Matsumoto Yuji Nakai Masaru Hoshino Koki Yamazaki Yoshiaki Takioto Satoru Takadera 《Bioscience, biotechnology, and biochemistry》2017,81(10):1926-1936
Tenascin-C (TNC), an extracellular matrix glycoprotein, plays a pivotal role in tumor growth. However, the mechanism whereby TNC affects tumor biology remains unclear. To investigate the exact role of TNC in primary tumor growth, a mouse mammary tumor cell line, GLMT1, was first developed. Subsequently, global gene expression in GLMT1-derived tumors was compared between wild-type (WT) and TNC-knockout (TNKO) mice. Tumors in WT mice were significantly larger than those in TNKO mice. DNA microarray analysis revealed 447 up and 667 downregulated in the tumors inoculated into TNKO mice as compared to tumors in WT mice. Validation by quantitative gene expression analysis showed that Tnc, Cxcl1, Cxcl2, and Cxcr2 were significantly upregulated in WT mice. We hypothesize that TNC stimulates the CXCL1/2-CXCR2 pathway involved in cancer cell proliferation. 相似文献
2.
Abstract The amounts of mRNA and protein of plasma membrane proton-ATPase were measured in the salt-tolerant yeast Zygosaccharomyces rouxii by Northern and Western blot analyses. Although their amounts were independent of growth phase, their synthesis were induced when yeast cells were grown in the presence of NaCl or were subjected to NaCl shock. This finding was consistent with our previous result that plasma membrane proton-ATPase activity was elevated in Z. rouxii cells grown in medium containing high concentrations of NaCl. 相似文献
3.
4.
5.
The lectin-binding patterns of the cells involved in amelogenesis and dentinogenesis in developing teeth of rats were studied. Undifferentiated odontogenic epithelia exhibited very slight staining with almost all of the lectins examined. The lectin-staining affinities of secretory ameloblasts could be divided into two categories: Concanavalin-A (Con-A), Wheat germ agglutinin (WGA) and Soybean agglutinin (SBA) binding occurred from the middle to apical cytoplasm, whereas Ricinus communis agglutinin-I (RCA-I) and Ulex europeus I (UEA-I) binding predominated in the basal regions. The cells of the stratum intermedium exhibited relatively strange lectin staining, which appeared to be dependent on ameloblastic maturation. The basement membranes in undifferentiated epithelia were markedly positive for lectin binding. Odontoblasts showed moderate Con-A staining on the apical side of the cells, as well as slight-to-moderate reactions with WGA and SBA. Pulp cells and dental papillae showed slight-to-moderate lectin staining, and predentin and dentin were also moderately positive for Con-A and RCA-I binding and slightly so for WGA and SBA. The lectin-binding affinities were enhanced during the formation of enamel and dentin, and appeared to be dependent on the degree of cellular differentiation in ameloblasts and odontoblasts. 相似文献
6.
The role of the Trp6 residue in the biological activity of the hypotensive peptide xenopsin (<Glu-Gly-Lys-Arg-Pro-Trp-Ile-Leu-OH) was investigated. This residue was satisfactorily reduced to 2,3-dihydro-Trp on treatment with excess pyridine-borane in trifluoroacetic acid without any detectable change in other parts of the molecule. The analogous peptide, (Lys2, Gly3) xenopsin, was also reduced in a similar manner. Both reduction products were purified by gel filtration and characterized by UV absorption, amino acid composition, and structural analysis.The reduced peptides were assayed on the fundus strip of isolated rat stomach and were found to possess less than 1 percent of the activity of the original peptides. Although each of the reduced analogs had an indoline substituted for an indole in the tryptophyl residue, their biological activity was virtually lost. This suggests that the tryptophyl residue of xenopsin is crucial for its biological activity. 相似文献
7.
8.
Hatsumi Taniguchi Kiyoshi Sato Midori Ogawa Takezo Udou Yasuo Mizuguchi 《Microbiology and immunology》1984,28(3):327-337
Phage Vf33, a filamentous phage about 1,400 nm long and 7 nm wide, specific for Vibrio parahaemolyticus, was isolated and characterized. The buoyant density of Vf33 in CsCl was 1.292 g/cm3. As with other filamentous phages, the lytic activity of Vf33 was resistant to heating below 80 C and to treatment with diethylether, acetone or methanol but sensitive to chloroform. The nucleic acid of this phage is single-stranded circular DNA 8.4 kb in size. The viral genome was converted to a double-stranded replicative form in the host cell. Among the strains tested, only V. parahaemolyticus strains possessing K38 antigen was sensitive to the phage. 相似文献
9.
Carbon (C) and nitrogen (N) content and growth/grazing characteristicsof the heterotrophic dinoflagellate Noctiluca scintillans wereexamined in laboratory cultures at 24°C. The C and N contentsof N.scintillans per unit cell volume were 2.3 x 10 相似文献
10.