全文获取类型
收费全文 | 92篇 |
免费 | 8篇 |
国内免费 | 9篇 |
专业分类
109篇 |
出版年
2024年 | 1篇 |
2022年 | 1篇 |
2021年 | 3篇 |
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 7篇 |
2013年 | 2篇 |
2012年 | 3篇 |
2011年 | 5篇 |
2010年 | 5篇 |
2009年 | 2篇 |
2008年 | 3篇 |
2007年 | 5篇 |
2006年 | 4篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2001年 | 2篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 4篇 |
1972年 | 1篇 |
排序方式: 共有109条查询结果,搜索用时 0 毫秒
101.
W H Moger 《Biology of reproduction》1983,28(3):528-535
The effects of various calcium-channel blockers on androgen production by collagenase-dispersed mouse testicular interstitial cells were investigated. Cobalt caused a dose-dependent inhibition of the maximum rate of luteinizing hormone (LH)-stimulated androgen production without altering the concentration of LH required for half maximum stimulation (EC50). Nickel and manganese also inhibited LH-stimulated steroidogenesis but were less potent than cobalt. The major site at which cobalt treatment inhibited steroidogenesis was beyond cAMP formation and before 3 beta-hydroxysteroid dehydrogenase. This conclusion was based on the observation that cobalt inhibited dibutyryl cAMP-stimulated androgen production but did not affect protein synthesis and pregnenolone-supported androgen production. Androgen production was unaffected by the organic calcium-channel blockers verapamil and the (+) and (-) enantiomers of D600 at concentrations less than 0.1 mM. At a concentration of 0.1 mM the organic calcium-channel blockers inhibited LH- and dibutyryl cAMP-stimulated androgen production. Unlike cobalt, the organic calcium-channel blockers also inhibited pregnenolone-supported androgen production and reduced the rate of protein synthesis. Similarities between the effects of cobalt in the present study and previous reports of the effects of reduced extracellular calcium concentrations on androgen production suggest that cobalt inhibits androgen production as a result of its ability to block calcium influx. The calcium channels involved in the steroidogenic process appear, however, to be relatively insensitive to the organic calcium-channel blockers. 相似文献
102.
Natalie L. Garrett Peter Vukusic Feodor Ogrin Evgeny Sirotkin C. Peter Winlove Julian Moger 《Journal of biophotonics》2009,2(3):157-166
We show that naturally occurring chitinous nanostructures found on the wings of the Graphium butterfly can be used as substrates for surface‐enhanced Raman scattering when coated with a thin film of gold or silver. The substrates were found to exhibit excellent biocompatibility and sensitivity, making them ideal for protein assaying. An assay using avidin/biotin binding showed that the substrates could be used to quantify protein binding directly from changes in the surface‐enhanced Raman scattering (SERS) spectra and were sensitive over a concentration range comparable with a typical enzyme‐linked immunosorbent assays (ELISA) assay. A biomimetic version of the wing nanostructures produced using a highly reproducible, large‐scale fabrication process, yielded comparable enhancement factors and biocompatibility. The excellent biocompatibility of the wings and biomimetic substrates is unparalleled by other lithographically produced substrates, and this could pave the way for widespread application of ultrasensitive SERS‐based bioassays. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
103.
Exposure to short photoperiods induces gonadal regression in the golden hamster. This is accompanied by a fall in serum gonadotropins and changes in hypothalamic neurotransmitter turnover. We have attempted to correlate these changes with alterations in neurotransmitter receptor binding parameters. Compared to hamsters held in long photoperiods, opiate ([3H] naloxone) binding in hamsters exposed to short photoperiods is elevated in whole brain and in cerebral cortex but not in hypothalamus. However, beta-adrenergic ([3H] dihydroalprenolol) and benzodiazepine ([3H] flunitrazepam) binding are unaffected in whole brain, cerebral cortex or hypothalamus. Thus, changes in hypothalamic noradrenaline turnover rate previously reported may not be correlated with changes in beta-adrenergic binding. 相似文献
104.
An empirical adjustment to the likelihood ratio statistic 总被引:2,自引:0,他引:2
105.
Noncontact dipole effects on channel permeation. III. Anomalous proton conductance effects in gramicidin 总被引:3,自引:2,他引:1 下载免费PDF全文
LR Phillips CD Cole RJ Hendershot M Cotten TA Cross DD Busath 《Biophysical journal》1999,77(5):2492-2501
Proton transport on water wires, of interest for many problems in membrane biology, is analyzed in side-chain analogs of gramicidin A channels. In symmetrical 0.1 N HCl solutions, fluorination of channel Trp(11), Trp-(13), or Trp(15) side chains is found to inhibit proton transport, and replacement of one or more Trps with Phe enhances proton transport, the opposite of the effects on K(+) transport in lecithin bilayers. The current-voltage relations are superlinear, indicating that some membrane field-dependent process is rate limiting. The interfacial dipole effects are usually assumed to affect the rate of cation translocation across the channel. For proton conductance, however, water reorientation after proton translocation is anticipated to be rate limiting. We propose that the findings reported here are most readily interpreted as the result of dipole-dipole interactions between channel waters and polar side chains or lipid headgroups. In particular, if reorientation of the water column begins with the water nearest the channel exit, this hypothesis explains the negative impact of fluorination and the positive impact of headgroup dipole on proton conductance. 相似文献
106.
107.
108.
Groups of seven intact male Long-Evans hooded rats were housed with pups for 1, 7, 14, or 22 days and their parental behavior was recorded each day. All but one male showed parental behavior. Twenty-eight control males were housed without pups. At the end of each observation period the males were decapitated and their trunk blood was collected for hormone analysis by radioimmunoassay. Males with pups had lower prolactin levels than control males on all 4 days but did not differ in leutinizing hormone, follicle-stimulating hormone, or testosterone levels from males without pups. Both prolactin and testosterone levels were correlated positively with the frequency of parental behavior, suggesting that the males which are behaviorally the most responsive to infants are also hormonally the most responsive. 相似文献
109.
M Nicosia W H Moger C A Dyer M M Prack D L Williams 《Molecular endocrinology (Baltimore, Md.)》1992,6(6):978-988
Apolipoprotein-E (apoE) is a constituent of various lipoproteins and is a ligand for cellular lipoprotein receptors. Unlike most apolipoproteins, apoE is synthesized in peripheral tissues, including those engaged in steroidogenesis. ApoE expression in adrenal cells inhibits cholesterol utilization for steroid synthesis and blocks signal transduction via the protein kinase-A pathway. In cultured ovarian thecal/interstitial cells, exogenous apoE has been shown to inhibit LH-induced androgen synthesis. These findings support a role for apoE as an autocrine or paracrine factor involved in regulating steroidogenesis. In the present study in situ hybridization was used to identify cell types that express apoE mRNA in ovaries from rats with a 4-day estrous cycle, from pregnant rats, from immature rats treated with PMSG to stimulate follicular development, and from PMSG-treated rats that were subsequently administered hCG to stimulate ovulation and luteinization. ApoE mRNA was localized to theca and interstitial cells of follicles in animals at all stages of the estrous cycle as well as in immature rats treated with PMSG. ApoE mRNA was not detected in oocytes, cumulus cells, or granulosa cells. High levels of apoE mRNA also were expressed by localized clusters of presumptive macrophages in atretic follicles and degenerating corpora lutea. This complex pattern of expression may indicate that apoE has multiple functions in the rat ovary. ApoE made by theca and interstitial cells may act locally as an autocrine factor to regulate androgen production. ApoE made in atretic follicles and regressing corpora lutea may serve to facilitate local transport and reutilization of lipid released as these structures degenerate. 相似文献