全文获取类型
收费全文 | 901693篇 |
免费 | 91555篇 |
国内免费 | 286篇 |
出版年
2018年 | 8732篇 |
2017年 | 8331篇 |
2016年 | 11664篇 |
2015年 | 14704篇 |
2014年 | 17598篇 |
2013年 | 25473篇 |
2012年 | 28564篇 |
2011年 | 29520篇 |
2010年 | 20188篇 |
2009年 | 18644篇 |
2008年 | 26468篇 |
2007年 | 27581篇 |
2006年 | 25838篇 |
2005年 | 24793篇 |
2004年 | 24616篇 |
2003年 | 23712篇 |
2002年 | 23307篇 |
2001年 | 39106篇 |
2000年 | 38818篇 |
1999年 | 31001篇 |
1998年 | 11392篇 |
1997年 | 11548篇 |
1996年 | 10930篇 |
1995年 | 10101篇 |
1994年 | 9738篇 |
1993年 | 9863篇 |
1992年 | 25331篇 |
1991年 | 24976篇 |
1990年 | 24264篇 |
1989年 | 23740篇 |
1988年 | 21810篇 |
1987年 | 20988篇 |
1986年 | 19518篇 |
1985年 | 19482篇 |
1984年 | 16022篇 |
1983年 | 13923篇 |
1982年 | 10495篇 |
1981年 | 9480篇 |
1980年 | 8868篇 |
1979年 | 14953篇 |
1978年 | 11879篇 |
1977年 | 10689篇 |
1976年 | 10127篇 |
1975年 | 11447篇 |
1974年 | 12354篇 |
1973年 | 12201篇 |
1972年 | 11237篇 |
1971年 | 10091篇 |
1970年 | 8834篇 |
1969年 | 8673篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
D C Rideout M Lambert D A Kendall G R Moe D G Osterman H P Tao I B Weinstein E T Kaiser 《Journal of cellular physiology》1985,124(3):365-371
Four amphiphilic peptides, each with net charges of +2 or more at neutrality and molecular weights under 4 kilodaltons, were found to mediate the adhesion of normal rat kidney fibroblasts to polystyrene surfaces. Two of these peptides, a model for calcitonin (peptide 1, MCT) and melittin (peptide 2, MEL), form amphiphilic alpha-helical structures at aqueous/nonpolar interfaces. The other two, a luteinizing hormone-releasing hormone model (peptide 3, LHM) and a platelet factor model (peptide 4, MPF) form beta-strand structures in amphiphilic environments. Although it contains only 10 residues, LHM mediated adhesion to surfaces coated with solutions containing as little as 10 pmoles/ml of peptide. All four of these peptides were capable of forming monolayers at air-buffer interfaces with collapse pressures greater than 20 dynes/cm. None of these four peptides contains the tetrapeptide sequence Arg-Gly-Asp-Ser, which has been associated with fibronectin-mediated cell adhesion. Ten polypeptides that also lacked the sequence Arg-Gly-Asp-Ser but were nonamphiphilic and/or had net charges less than +2 at neutrality were all incapable of mediating cell adhesion (Pierschbacher and Ruoslahti, 1984). The morphologies of NRK cells spread on polystyrene coated with peptide LHM resemble the morphologies on fibronectin-coated surfaces, whereas cells spread on surfaces coated with MCT or MEL exhibit strikingly different morphologies. The adhesiveness of MCT, MEL, LHM, and MPF implies that many amphiphilic cationic peptides could prove useful as well defined adhesive substrata for cell culture and for studies of the mechanism of cell adhesion. 相似文献
993.
E E Vasar L K Riago A Kh Soosaar A M Nurk M O Ma?mets 《Biulleten' eksperimental'no? biologii i meditsiny》1985,100(12):711-713
Subcutaneous administration of caerulein (100-500 micrograms/kg) significantly reduced the development of picrotoxin (8 mg/kg) seizures in male mice. The same doses of caerulein inhibited 3H-flunitrazepam binding in in vivo experiments. Proglumide, an antagonist of cholecystokinin receptors, in low dose (5 mg/kg) potentiated the effects of caerulein (100 micrograms/kg), whereas the administration of proglumide in high dose (25 mg/kg) reduced the action of caerulein on 3H-flunitrazepam binding and picrotoxin seizures. Caerulein (5-1000 nM) decreased 3H-flunitrazepam binding in in vitro experiments only after supplementation of the binding medium with 120 mM NaCl and 5mM KCl. The results suggest the possible interaction of caerulein with chloride ionophor. It seems probable that the direct interaction of caerulein with chloride ionophor in involved in the inhibitory effect of caerulein on picrotoxin seizures and 3H-flunitrazepam binding. 相似文献
994.
995.
Reinnervation of experimental superficial wounds in rats 总被引:1,自引:0,他引:1
Sensory reinnervation of a superficial skin wound in the rat was studied by labeling sensory axons with anterogradely transported wheat germ agglutinin-horseradish peroxidase. Reinnervation starts after 3 days from the edge of the wound as well as from beneath the wound. About 2 weeks after the production of the wound, some hyperinnervation appears to be present, but after a few additional weeks, the innervation pattern is essentially normal. The results indicate that structural recovery of sensory axons is rapid and probably complete when skin wounds heal with no or minimal scar formation. 相似文献
996.
I. T. Rass 《Biochemistry. Biokhimii?a》2010,75(3):353-366
Glucocorticoid hormones directly or indirectly control virtually all metabolic and physiological processes. Glucocorticoids
are also shown to act on a multitude of genes, enzyme systems, and proinflammatory factors, but for these hormones there is
no representative index of action on metabolism similar to glucose content in blood for insulin. The absence of such an index
prevents the assessment of tissue provision with these hormones under various conditions and seems to be an essential cause
of complications associated with the clinical use of glucocorticoid preparations. Considering specific features of tyrosine
metabolism and data obtained experimentally and on a clinical model (adrenalectomy in rats and substitution therapy in endocrine
disease), blood content of this amino acid seems promising as such an index. Based on comparing results of glucocorticoid
treatment in patients with systemic lupus erythematosus with changes in their blood tyrosine contents, the pharmacological
effect of glucocorticoid preparations is suggested to be mainly due to compensating a relative shortage of these hormones. 相似文献
997.
998.
Scott A. Snyder 《Chirality》2010,22(5):542-542
999.
1000.
R Sitia H Kikutani A Rubartelli Y Bushkin J Stavnezer U Hammerling 《Journal of immunology (Baltimore, Md. : 1950)》1982,128(2):712-716
Three different forms of alpha-chains are synthesized by BF0.3 and 615.2, two cloned cell lines derived from the murine B lymphoma 1.29. The three forms of alpha-chains differ in size, pI, cellular location, and rate of turnover. They were identified by means of lactoperoxidase-catalyzed radioiodination, internal 14C or 35S labeling, and immunofluorescence techniques as membrane-bound(alpha m), secreted (alpha s), and intracellular (alpha ic) proteins. Comparison of immunoglobulin products of the two lymphoma lines with those of a hybridoma cell line, Id 150, which secretes IgA of the 1.29 idiotype but lacks membrane IgA, confirmed the assignments of alpha m, alpha s, and alpha ic. Results of biosynthetic labeling of BF0.3, 615.2, and Id 150 in the presence and absence of tunicamycin suggest that the difference in m.w. and charge observed between alpha m and alpha s can be attributed to differences in primary amino acid structure rather than different degrees of glycosylation. 相似文献