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61.
Induction of follicle stimulating hormone receptor in the granulosa cells of intact immature rat ovary by diethylstilbesterol,
an estrogen, has been studied.
A single injection of 4 mg of diethylstilbesterol produced 72 h later a 3-fold increase in follicle stimulating hormone receptor
concentration as monitored by [125I]-oFSH binding to isolated cells. The newly induced receptors were kinetically indistinguishable from the preexisting ones, as
determined by Lineweaver-Burk plot of the binding data. The induced receptors were functional as evidenced by increased ability
of the granulosa cells to incorporate [3H]-leucine into cellular proteins.
Neutralization of endogenous follicle stimulating hormone and luteinizing hormone by administering specific antisera had no
effect on the ability of diethylstilbesterol to induce follicle stimulating hormone receptors, whereas blockade of endogenous
prolactin secretion by ergobromocryptin administration significantly inhibited (∼ 30 %) the response to diethylstilbesterol;
this inhibition could be completely relieved by ovine prolactin treatment. However, ovine prolactin at the dose tried did
not by itself enhance follicle stimulating hormone receptor level.
Administration of ergobromocryptin to adult cycling rats at noon of proestrus brought about as measured on diestrusII, (a) a reduction of both follicle stimulating hormone (∼ 30 %) and luteinizing hormone (∼ 45 %) receptor concentration in granulosa
cells, (b) a drastic reduction in the ovarian tissue estradiol with no change in tissue progesterone and (c) reduction in
the ability of isolated granulosa cells to convert testosterone to estradiol in response to follicle stimulating hormone.
Ergobromocryptin treatment affected only prolactin and not follicle stimulating hormone or luteinizing hormone surges on the
proestrus evening. Treatment of rats with ergobromocryptin at proestrus noon followed by an injection of ovine prolactin (1
mg) at 1700 h of the same day completely reversed the ergobromocryptin induced reduction in ovarian tissue estradiol as well
as the aromatase activity of the granulosa cells on diestrus II, thus suggesting a role for proestrus prolactin surge in the
follicular maturation process 相似文献
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66.
We have examined the monthly variations in sperm output and attempted to correlate the profiles of endocrine hormones secreted
with the sperm counts throughout the year in the adult male bonnet monkey. As previously reported, there was a distinct spurt
in sperm output beginning September through December months. A concomitant increase in serum testosterone and prolactin concentrations
were also noted during September through November (mid and post-monsoon season). Although there was a marked increase in gonadotropin
releasing hormone stimulated testosterone secretion, the peak testosterone concentrations post gonadotropin releasing hormone
injection did not vary significantly (P > 0.05) throughout the year. Basal serum follicle stimulating hormone concentrations did not vary significantly (P > 0.05) during April to June months compared to September-November months. Serum inhibin concentration remained unaltered
throughout the year, except in the month of March. The results of this study provide evidence for annual rhythms in prolactin
and testosterone secretion and a distinct seasonality in the sperm output of the adult male bonnet monkey, but the pituitary
responsiveness to exogenous gonadotropin releasing hormone remains unaltered throughout the year. Because of the existence
of seasonality as noted in the present study, future studies which utilize the adult male bonnet monkey as an experimental
model need to take into consideration the seasonal effects on reproductive function in this species. 相似文献
67.
The presence of a gonadotropin receptor binding inhibitor in pooled porcine follicular fluid has been demonstrated. Porcine follicular fluid fractionation on DE-32 at near neutral pH, followed by a cation exchange chromatography on SPC-50 and Cibacron blue affinity chromatography, yielded a partially purified gonadotropin receptor binding inhibitor (GI-4). The partially purified GI binding inhibitor inhibited the binding of both 125I labelled hFSH and hCG to rat ovarian receptor preparation. SDS electrophoresis of radioiodinated partially purified GI followed by autoradiography made it possible to identify the binding component as a protein of molecular weight of 80,000. Subjecting 125I labelled GI-4 to chromatography on Sephadex G-100 helped obtain a homogeneous material, GI-5. The 125I labelled GI-5 exhibited in its binding to ovarian membrane preparations characteristics typical of a ligand-receptor interaction such as saturability, sensitivity to reaction conditions as time, ligand and receptor concentrations and finally displaceability by unlabelled inhibitor as well as FSH and hCG in a dose dependent manner. This material could bind ovarian receptors for both FSH and LH, its binding being inhibited by added FSH or hCG in a dose dependent manner. 相似文献
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Administration of human chorionic gonadotropin to pregnant bonnet monkeys(Macaca radiata) at 55–60 days and 130–140 days of pregnancy resulted in a significant increase in serum progesterone levels. This effect
could be observed even in lutectomized monkeys. However, no significant change in the serum estrogen level was noticed. These
results suggest that although no chorionic gonadotropin is detectable in the serum after 35 days of pregnancy, the foetoplacental
steroidogenic system is still responsive to exogenous gonadotropic stimulation. 相似文献
70.
We reported the presence of a 80 kDa polypeptide in porcine follicular fluid that inhibited the binding of 125I-radiolabelled hFSH as well as hCG to the rat ovarian gonadotropin receptors. In the present study, the biological activity of the receptor binding inhibitor is determined using an in vitro bioassay procedure. Granulosa cells isolated from PMSG primed immature rat ovaries respond to exogenously added gonadotropins in terms of progesterone production. Addition of fractions containing the gonadotropin receptor binding inhibitory activity inhibited progesterone production stimulated by the gonadotropins in a dose-dependent fashion. The receptor binding inhibitory activity was also capable of inhibiting progesterone production stimulated by PMSG, which has both FSH- and LH-like activities in rats. In contrast, progesterone production stimulated by dbcAMP was not inhibited by the receptor binding inhibitor. This result indicates that the site of action of the inhibitor is proximal to the formation of the cAMP. The above observations point out to a possible role for this factor in modulating gonadotropin activity at the ovarian level. 相似文献