全文获取类型
收费全文 | 3281篇 |
免费 | 297篇 |
国内免费 | 1篇 |
出版年
2021年 | 61篇 |
2020年 | 25篇 |
2019年 | 37篇 |
2018年 | 31篇 |
2017年 | 28篇 |
2016年 | 76篇 |
2015年 | 100篇 |
2014年 | 123篇 |
2013年 | 156篇 |
2012年 | 166篇 |
2011年 | 181篇 |
2010年 | 99篇 |
2009年 | 88篇 |
2008年 | 157篇 |
2007年 | 138篇 |
2006年 | 109篇 |
2005年 | 117篇 |
2004年 | 112篇 |
2003年 | 121篇 |
2002年 | 108篇 |
2001年 | 106篇 |
2000年 | 99篇 |
1999年 | 93篇 |
1998年 | 43篇 |
1997年 | 52篇 |
1996年 | 36篇 |
1995年 | 33篇 |
1994年 | 44篇 |
1993年 | 28篇 |
1992年 | 67篇 |
1991年 | 55篇 |
1990年 | 68篇 |
1989年 | 61篇 |
1988年 | 47篇 |
1987年 | 56篇 |
1986年 | 65篇 |
1985年 | 71篇 |
1984年 | 47篇 |
1983年 | 48篇 |
1982年 | 36篇 |
1981年 | 31篇 |
1979年 | 36篇 |
1978年 | 27篇 |
1975年 | 23篇 |
1974年 | 23篇 |
1973年 | 21篇 |
1972年 | 19篇 |
1971年 | 17篇 |
1970年 | 17篇 |
1969年 | 20篇 |
排序方式: 共有3579条查询结果,搜索用时 109 毫秒
1.
2.
Insulin release from a cloned hamster B-cell line (HIT-T15). The effects of glucose, amino acids, sulphonylureas and colchicine 总被引:1,自引:0,他引:1
D G Lambert K Hughes T W Atkins 《Biochemical and biophysical research communications》1986,140(2):616-625
Insulin release from statically incubated HIT-T15 cells was maximally stimulated by glucose, L-arginine and L-leucine. L-arginine stimulated insulin release in the absence of glucose. Glucose induced insulin release was potentiated by the addition of L-leucine, L-arginine and the two in combination. Both glibenclamide and chlorpropamide stimulated insulin release from HIT-T15 cells. Glibenclamide was the more potent and equivalent in insulinotrophic action to 7.5 mmol/l glucose. Only chlorpropamide significantly potentiated glucose induced insulin release. Perifused HIT-T15 cells produced a reproducible biphasic insulin response to glucose challenge which was characterised by a pronounced and sustained first phase and a reduced second phase. The stimulation of phase I by glibenclamide alone and the inhibition of phase II of glucose induced insulin release by colchicine suggested the presence of a readily available pool of insulin granules which was not rapidly restored by insulin biosynthesis and granule margination. 相似文献
3.
4.
5.
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
6.
7.
After ovulation, female African catfish are strongly attracted by the odor of male conspecifics. This attraction depends on the presence of the seminal vesicle, a part of the male reproductive organs. Removal of the seminal vesicle illustrates this fact. A low dose of seminal vesicle fluid, added to the water, appears to be highly attractive for catfish which have ovulated. Fractionation of the fluid and testing of the different fractions shows that steroid glucuronides could be responsible for the attraction. These steroid glucuronides can be identified with gas chromatographic-mass spectrometric analysis. A mixture of glucuronides, prepared to resemble the composition of the seminal vesicle fluid, evokes a dose-dependent attraction. The most potent odorant, observed by measuring electrical responses from the olfactory epithelium and from the olfactory tract appears to be 3α,17α-dihydroxy-5β-pregnan-20-one-3α-glucuronide. 相似文献
8.
J C Lambert G Vallette G E Seralini R Vranckx E Nunez C Stora 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1986,302(9):353-358
Data are presented which indicate a possible action of alpha-fetoprotein (AFP) on female germinal cells. The in vitro maturation of mature mice oocytes was significantly inhibited when mouse AFP replaced albumin in the culture medium. In addition, the degenerative aspect of oocytes cultured with AFP seemed to indicate that this me?otic inhibition was caused by a premature degeneration of oocytes rather than by a blockage at a specific stage of maturation. Thus AFP, perhaps through its ligands, may play a role in the reduction of germinal cells during fetal and immediate post-natal life rather than in the arrest of me?osis at the diplotene stage. 相似文献
9.
A. Verrips Gerry C. H. Steenbergen-Spanjers J. A. F. M. Luyten R. A. Wevers John H. J. Wokke Fons J. M. Gabreëls Bert G. Wolthers Lambert P. W. J. van den Heuvel 《Human genetics》1997,100(2):284-286
We report a new mutation in the sterol 27-hydroxylase (CYP 27) gene in a Dutch family with cerebrotendinous xanthomatosis:
a G→A transition in the splice donor site in intron 4. This mutation leads to skipping of exon 4, resulting in a loss of 66
amino acids in the CYP 27 enzyme molecule.
Received: 15 March 1997 / Accepted: 26 March 1997 相似文献
10.