全文获取类型
收费全文 | 3392篇 |
免费 | 364篇 |
国内免费 | 3篇 |
出版年
2021年 | 34篇 |
2019年 | 26篇 |
2017年 | 26篇 |
2016年 | 44篇 |
2015年 | 76篇 |
2014年 | 95篇 |
2013年 | 139篇 |
2012年 | 157篇 |
2011年 | 180篇 |
2010年 | 118篇 |
2009年 | 92篇 |
2008年 | 124篇 |
2007年 | 163篇 |
2006年 | 133篇 |
2005年 | 137篇 |
2004年 | 172篇 |
2003年 | 143篇 |
2002年 | 144篇 |
2001年 | 67篇 |
2000年 | 74篇 |
1999年 | 80篇 |
1998年 | 52篇 |
1997年 | 38篇 |
1996年 | 33篇 |
1995年 | 27篇 |
1994年 | 29篇 |
1993年 | 37篇 |
1992年 | 49篇 |
1991年 | 51篇 |
1990年 | 45篇 |
1989年 | 50篇 |
1988年 | 47篇 |
1987年 | 39篇 |
1986年 | 40篇 |
1985年 | 51篇 |
1984年 | 45篇 |
1983年 | 33篇 |
1982年 | 50篇 |
1981年 | 38篇 |
1980年 | 46篇 |
1979年 | 36篇 |
1978年 | 45篇 |
1977年 | 39篇 |
1976年 | 40篇 |
1975年 | 28篇 |
1974年 | 40篇 |
1973年 | 32篇 |
1972年 | 40篇 |
1969年 | 32篇 |
1967年 | 24篇 |
排序方式: 共有3759条查询结果,搜索用时 31 毫秒
41.
Human follicular fluid from healthy mature Graafian follicles and from pathologic ovarian cyst fluid was found to be inhibitory to progesterone-induced meiotic maturation of oocytes from the South African clawed toad, Xenopus laevis. Human follicular fluid but not human serum, collected from the same individuals, demonstrated a linear dose-response inhibition on the maturation of oocytes in the Xenopus assay system. These findings indicate that the human follicular and cyst fluids contain oocyte maturation inhibitor (OMI). This human OMI was inactivated when subjected to a boiling water bath for 2 min. The OMI action was shown to be reversible in its inhibitory action. The fact that OMI can act directly on the oocyte was demonstrated by its inhibitory action on maturation in defolliculated oocytes. The findings demonstrate that the inhibitory action of human OMI is not species-specific. Xenopus oocytes provide a simple, readily available, year-round bioassay material for testing follicular oocyte maturation inhibitor. 相似文献
42.
Richard B. Silverman A. Jabbar Muztar Mark A. Levy James D. Hirsch 《Life sciences》1983,32(24):2717-2723
The effects of intraperitoneal administration of (S)-4-amino-5-fluoropentanoic acid, a mechanism-based covalent inactivator of γ-aminobutyric acid transaminase (GABA-T), on whole brain GABA metabolism in mice were investigated. A dose-dependent and time-dependent irreversible inactivation of GABA-T was observed with a concomitant increase in whole brain GABA levels. The compound exhibited no nor time-dependent inhibition of glutamate decarboxylase (GAD), alanine transaminase, or aspartate transaminase (Asp-T). It was, however, a potent competitive reversible inhibitor of GAD and a weak competitive inhibitor of Asp-T. The chloro analogue, (S)-4-amino-5-chloropentanoic acid, was ineffective. 相似文献
43.
Bonnie J. Reger Maurice S.B. Ku Jeffrey W. Pottert John J. Evans 《Phytochemistry》1983,22(5):1127-1132
The ribulose-1,5-bisphosphate carboxylase/oxygenase purified from maize (a C4 monocot) to homogeneity has a MW of532 000 and sedimentation coeffici 相似文献
44.
Hemming Fiona J. Begeot Martine Dubois Maurice P. Dubois Paul M. 《Cell and tissue research》1983,234(2):427-437
Corticotropes of rat fetuses aged 16, 18 and 21 days were localized by the indirect antibody-enzyme method on semithin sections of the pituitary. The development of the ultrastructure of these cells was observed on consecutive ultrathin sections. In comparison with previous data our present results show that identification of a fetal cell type cannot be based entirely on morphological criteria. The structural peculiarities of corticotropes obtained from studies in vivo are compared with those observed in cells maintained in vitro. 相似文献
45.
The identification and regionalization of four pituitary parenchymal cell types, gonadotrophs, mammotrophs, somatotrophs and thyrotrophs, were studied in the baboon (Papio cynocephalus) hypophysis using immunocytochemistry. The gonadotrophs were homogeneously distributed throughout the entire pars distalis. Both mammotrophs and somatotrophs predominate at the superior and inferior poles of the organ. The medial and anteromedial regions are populated by mammotrophs and thyrotrophs, while the lateral and posterior portions of the pars distalis contain large numbers of somatotrophs. 相似文献
46.
47.
Positioning Flagellar Genes in Escherichia coli by Deletion Analysis 总被引:12,自引:10,他引:2
48.
Separation of a New Deoxyribonucleic Acid Polymerase from Vaccinia-infected HeLa Cells 总被引:5,自引:4,他引:1
下载免费PDF全文
![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
HeLa cell deoxyribonucleic acid (DNA) polymerase was purified about 100-fold by sequential column chromatography on phosphocellulose, hydroxylapatite, and Bio Rex 70. A new form of DNA polymerase found in vaccinia virus-infected cells was separated from HeLa DNA polymerase by chromatography on diethylamino-ethyl cellulose. The new form was also purified approximately 100-fold in the same manner as the HeLa DNA polymerase. In addition to chromatographic differences, the two enzymes differed with regard to primer response, relative activity at high pH, inactivation by heat and p-chloromercuribenzoate, and inhibition by vaccinia antiserum. 相似文献
49.
Maurice Cross 《BMJ (Clinical research ed.)》1969,4(5686):808-809
50.
Therapy of Staphylococcal Infections in Monkeys. IV. Further Comparison of Triacetyloleandomycin and Erythromycins 总被引:4,自引:2,他引:2
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Intravenous inoculation of a penicillin-resistant, phage type 80/81 staphylococcus caused lethal infection in 8 of 15 untreated monkeys. Daily intragastric administration of 50 mg/kg of triacetyloleandomycin, erythromycin estolate, and erythromycin ethylsuccinate was followed by mortalities of 0 of 16, 3 of 16, and 3 of 10, respectively. At dose levels of 25 and 12.5 mg/kg, none of 7 and 4 of 7 receiving triacetyloleandomycin and erythromycin estolate, respectively, died, as compared to 3 of 4 deaths in controls. In vitro sensitivity data and serum antibacterial levels would suggest that triacetyloleandomycin would be the least effective therapeutically. However, this prediction was not fulfilled in these studies of experimental infections in monkeys wherein triacetyloleandomycin was a very effective antimicrobial agent. 相似文献