全文获取类型
收费全文 | 300篇 |
免费 | 12篇 |
国内免费 | 9篇 |
出版年
2023年 | 5篇 |
2022年 | 3篇 |
2021年 | 10篇 |
2020年 | 4篇 |
2019年 | 9篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 5篇 |
2014年 | 13篇 |
2013年 | 9篇 |
2012年 | 5篇 |
2011年 | 12篇 |
2010年 | 8篇 |
2009年 | 4篇 |
2008年 | 8篇 |
2007年 | 10篇 |
2006年 | 5篇 |
2005年 | 8篇 |
2004年 | 5篇 |
2003年 | 11篇 |
2002年 | 8篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1987年 | 7篇 |
1986年 | 2篇 |
1985年 | 12篇 |
1984年 | 7篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1977年 | 5篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1971年 | 1篇 |
排序方式: 共有321条查询结果,搜索用时 15 毫秒
1.
《Cryobiology》2019
Global amphibian declines have fueled an increased interest in amphibian assisted reproductive technologies. Within the genus Rhaebo, half of the species are experiencing decreasing population trends; however, insufficient information is available on many of these species’ reproductive biology. Using the smooth-sided toad, Rhaebo guttatus, we present effective methods for collecting and cryopreserving an example of Rhaebo sperm. Specifically, our findings show that administering 10 IU/g body weight of hCG (human chorionic gonadotropin) yields the most motile and concentrated sperm and that cryopreserving spermic urine in a solution of 5% DMFA (N,N-Dimethylformamide) and 10% trehalose returns sperm with a 33 ± 3% average post-thaw motility. These findings may represent an important step forward in developing techniques that can be safely applied to other, more vulnerable species within the Rhaebo genus. 相似文献
2.
Extracellular matrix influences hormone and protein production by human chorionic villi 总被引:4,自引:0,他引:4
Summary Increasing evidence confirms that the extracellular matrix greatly influences cell behaviour and function. Collagen and fibrin are in contact with trophoblast throughout pregnancy. To investigate whether these two matrices influence hormon production by the trophoblast, explants from first-trimester chorionic villi were cultured for up to 30 days either a) in medium with agitation, b) embedded in type-I collagen (three-dimensional gels), or c) embedded in fibrin (three-dimensional gels). The supernatant culture medium was changed every 48 h and tested by radioimmunoassay for hCG, progesterone and pregnancy-associated plasma protein A. In addition, after 3, 7, 15, and 30 days of culture villi were fixed and studied by light and electron microscopy. Embedding in the extracellular matrix showed higher and longer-lasting production rates of all measured products and superior structural preservation as compared to cultures with agitation. Collagen matrix proved to be superior to fibrin. As established by several tests, this difference was neither due to thrombin used to polymerize fibrinogen, nor to differences in the diffusion rates through the two different matrices used. We conclude that extracellular matrix, particularly collagen, influences the synthesis of trophoblastic products. Embedding of the villous explants in three-dimensional gels constitutes a new method for long-term cultures of chorionic villi.This study was presented at the workshop Placental-and decidual-specific protein synthesis and secretion: regulation, role and interaction, Zemun, Belgrade, Yugoslavia, 19–20 May, 1988 (Bischof and Castellucci 1988; see also J. Aplin 1989), and at the 11th Rochester Trophoblast Conference, Rochester, N.Y. USA, 9–12 October 1988 (Castellucci et al. 1988) 相似文献
3.
M Hattori K Ozawa K Wakabayashi 《Biochemical and biophysical research communications》1985,127(2):501-508
To elucidate a possible role of sialic acid moiety in the electrical heterogeneity of rat pituitary lutropin, seven components separated were individually treated with neuraminidase. Some intermediates with isoelectric points corresponding to the native components were concomitantly seen at the serial stages of the enzyme treatment. All the treated components showed an isoelectric point of about 10.0 which was the same to the isoelectric point of one of the seven components. Desialylation of the components with less biological activity caused enhancement of the in vitro cyclic AMP producing- and testosterone producing-activities as well as the binding activity to the receptor. It is concluded that the number of sialic acid moiety in lutropin is responsible for the charge heterogeneity and the biological potency of the hormone. 相似文献
4.
The performance of The Subhuman Primate Pregnancy Test Kit was evaluated for routine detection of early (days 19-21) pregnancy in the rhesus monkey. Out of 123 confirmed matings, 19 resulted in pregnancy. In the pregnant animals the kit had an accuracy of 73.7%. In the nonpregnant females the accuracy was higher, 88.5%. False positives were encountered in ovariectomized females as well as adult intact males. 相似文献
5.
Summary Gonadotropin releasing hormone enhanced guanylate cyclase [E.C.4.6.1.2] two- to threefold in pituitary, testis, liver and kidney. Dose response relationships revealed that at a concentration of 1 nanomolar, gonadotropin releasing hormone caused a maximal augmentation of guanylate cyclase activity and that increasing its concentration to the millimolar range caused no further enhancement of this enzyme. There was an absolute cation requirement for gonadotropin releasing hormone's enhancement of guanylate cyclase activity as there was no increase without any cation present. Gonadotropin releasing hormone could increase guanylate cyclase activity with either calcium or manganese in the incubation medium but more augmentation was observed with manganese. The data in this investigation suggest that guanylate cyclase may play a role in the mechanism of action of gonadotropin releasing hormone. 相似文献
6.
Using a specific radioimmunoassay for gonadotropin releasing hormone, the presence of gonadotropin releasing hormone like
material in the first trimester human placenta has been demonstrated. The material has been partially characterized using
carboxy methyl cellulose chromatography, high pressure gel permeation chromatography and reverse phase C18 high pressure liquid
chromatographic analysis. Analysis for bioactivity revealed that placental gonadotropin releasing hormone is much more active
than synthetic gonadotropin releasing hormone inin vitro rat pituitary lutinising hormone release assay.In vitro biosynthetic studies using labelled precursors and immunoaffinity chromatography indicated that first trimester human placenta
synthesizes gonadotropin releasing hormone like material. 相似文献
7.
Sexing the human fetus and identification of polyploid nuclei by DNA-DNA in situ hybridisation in interphase nuclei 总被引:1,自引:0,他引:1
J D West C M Gosden J R Gosden K M West Z Davidson C Davidson K H Nicolaides 《Molecular reproduction and development》1989,1(2):129-137
Samples of human adult lymphocytes, fetal lymphocytes, amniotic fluid cells, and chorionic villus cells were sexed independently by cytogenetics and DNA-DNA in situ hybridisation to a tritiated Y probe. For the in situ hybridisation analysis, the presence of Y bodies (hybridisation bodies) in 100 interphase nuclei were scored after autoradiography. In all, 82/83 samples were sexed in this way (one technical failure) and 78/82 were sexed by both in situ hybridisation and cytogenetics. There was complete agreement between the two methods. There was a considerable variation (40-100%) in the percentage of interphase nuclei with a hybridisation body among the male samples, but very few nuclei from female samples showed significant hybridisation. In situ hybridisation could be used to sex the conceptus when males but not females are at risk for various X-linked genetic disorders and may also be useful for detecting 45,X/46,XY mosaicism or polyploid/diploid mosaicism. This would be particularly useful for direct preparations of chorionic villus samples, which often prove difficult to analyse cytogenetically but offer the best means of avoiding maternal contamination. Some interphase nuclei had more than one hybridisation body, and this was most commonly found among amniotic fluid cells. Comparison of sizes of nuclei with one or two hybridisation bodies strongly suggested that most of the amniotic fluid cell nuclei with two hybridisation bodies were tetraploid. 相似文献
8.
The influence of the source of pregnant mares' serum gonadotropin (PMSG) on the num ber, quality, and in vitro development of mouse embryos before and after freezing was evaluated among three genotypes: N:NIH(S), C57BL/6N, and C3H/HeN-MTV?. Immature females were given PMSG from one of five commercial sources. Following col lection ( 116 hr later), embryos were evaluated for stage of development, and four-to eight-cell embryos were pooled within genotype and assigned to standardized fresh or freeze-thaw culture trials. Different PMSG sources stimulated the production of different num bers of total embryos (P < 0.05) but not necessarily more embryos suitable for freezing. Differences in embryo production among genotypes indicated that absolute embryo num bers using a single mouse genotype may not accurately reflect the potency of a specific gonadotropin source. The PMSG source also affected the ability of an embryo to survive in culture either immediately after collection or after frozen storage. The effect, however, was genotype specific, with some mouse strains being relatively insensitive to PMSG source, whereas gonadotropin source played a major role in determining in vitro viability in others. Development rates for freshly collected embryos differed, often inconsistently, from those of thawed embryos regardless of the PMSG source used, demonstrating that fresh embryo development cannot be used to estimate expected post-thaw survival. In vitro development of thawed embryos is influenced not only by genotype, but also the source of the gonadotropin used to promote follicular development and oocyte maturation. These findings may explain, in part, the wide variation in embryo viability and culture rates reported among laboratories and intraspecies animal populations. 相似文献
9.
10.
Charlotte L. Branchaud Cynthia G. Goodyer Harvey J. Guyda Yves Lefebvre 《In vitro cellular & developmental biology. Plant》1990,26(9):865-870
Summary We have compared hormone production by early gestation and term human placental trophoblasts cultured in Ham's F10 medium
containing 10% fetal bovine serum with that by cells cultured in serum-free HB102 medium. Mean daily production of progesterone
on Days 3 to 7 was approximately 25% less by both early gestation and term cells cultured in HB102 as compared to Ham's F10,
but production was maintained at a stable level for at least 7 d longer than the cells in Ham's. Estradiol production from
10−6
M dehydroepiandrosterone by both early gestation and term cells was comparable in both media. Human placental lactogen production
on Days 3 to 7 was 40% less by cells cultured in HB102. Human chorionic gonadotropin (hCG) output by early gestation cells
was also 50% less in HB102 but term cells in HB102 produced twice as much hCG as those in Ham's F10. 3B-Hydroxysteroid dehydrogenase
(3BHSD) activity in early gestation and term cells and 11B-hydroxysteroid dehydrogenase (11BHSD) activity of early gestation
cultures was comparable in the two media. 11BHSD activity was decreased in the term cultures, and this decrease was more marked
in Ham's than in HB102. Sulfatase and aromatase activities in the early gestation cultures were comparable in both media;
sulfatase activity was comparable and aromatase activity only 20% less in the term cells cultured in HB102. These results
indicate that serum-free HB102 supports differential function of human trophoblast cells and is useful for studies of placental
activity for as long as 14 d in culture. 相似文献