首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   753篇
  免费   32篇
耳鼻咽喉   2篇
儿科学   16篇
妇产科学   73篇
基础医学   58篇
口腔科学   2篇
临床医学   400篇
内科学   30篇
皮肤病学   34篇
神经病学   31篇
特种医学   2篇
外科学   42篇
综合类   9篇
预防医学   44篇
眼科学   1篇
药学   14篇
肿瘤学   27篇
  2023年   8篇
  2021年   4篇
  2018年   5篇
  2017年   6篇
  2016年   4篇
  2014年   3篇
  2013年   9篇
  2012年   8篇
  2011年   26篇
  2010年   9篇
  2009年   12篇
  2008年   9篇
  2007年   30篇
  2006年   7篇
  2005年   20篇
  2004年   14篇
  2003年   46篇
  2002年   15篇
  2001年   23篇
  2000年   13篇
  1999年   40篇
  1998年   50篇
  1997年   65篇
  1996年   38篇
  1995年   20篇
  1994年   28篇
  1993年   20篇
  1992年   34篇
  1991年   31篇
  1990年   14篇
  1989年   8篇
  1988年   15篇
  1987年   21篇
  1986年   17篇
  1985年   6篇
  1984年   8篇
  1983年   10篇
  1981年   6篇
  1980年   8篇
  1979年   8篇
  1978年   5篇
  1977年   6篇
  1976年   4篇
  1975年   3篇
  1974年   4篇
  1973年   8篇
  1971年   4篇
  1969年   3篇
  1968年   4篇
  1967年   4篇
排序方式: 共有785条查询结果,搜索用时 265 毫秒
11.
12.
Urogenital ageing and its effect on sexual health in older British women   总被引:4,自引:0,他引:4  
Objective To provide information on the extent of problems of urogenital ageing in older British women.
Design A MORI survey of a representative population sample of older British women.
Setting Home interviews.
Participants Two thousand and forty-five women aged 55–85+.
Results Urogenital symptoms had affected 48.8% of the women at some time, but no more than 11% were currently affected by individual symptoms; however, these were often of long duration. The majority (73%) were not sexually active, with lack of a partner being a factor for many. There was also a decreasing prevalence of sexual activity with increasing age. Those sexually active in the 65–74 year old age group (   n = 148  ) tended to have a similar sexual frequency (at least once per month) compared with the younger women studied. Approximately 12% of those who reported dyspareunia and/or vaginal dryness claimed a severe problem; 33% did not seek professional advice and 36% resorted to an over the counter remedy. Use of hormone replacement therapy was generally of relatively short duration. There was a declining gradient of ever-use with age.
Conclusions The extent of significant urogenital symptoms is relatively low, but some women are seriously affected and use self-help as well as professional assistance. The extent of sexual activity in older women and factors affecting this have been defined, and the effect of urogenital symptoms on sexual activity demonstrated.  相似文献   
13.
Objective To assess serum lipid and lipoprotein concentrations and oral glucose tolerance in postmenopausal women treated with 17β-oestradiol (2 mg/day) and cyclical dydrogesterone (10 mg/day for 14 days per 28 day cycle).
Design A 24 month prospective study of 29 women acting as their own controls. On-treatment samples were taken during the combined (oestrogen–progestogen) phase of therapy.
Setting Metabolic research unit in London.
Population Postmenopausal women with no previous exposure to hormone replacement therapy attending a menopause clinic in a London hospital.
Methods Fasting serum sampling and oral glucose tolerance testing.
Main outcome measures Serum lipids and lipoprotein concentrations and plasma glucose, insulin and C-peptide responses to an oral glucose load.
Results Restricting the analysis to the 17 women who completed the study, no effect was seen on serum triglyceride concentrations. There was a mean fall of 5.9% (95% CI 1.2 to −13.0) in concentrations of serum total cholesterol, reflecting the balance of a 10.7% fall (95% CI 4.3 to −25.8) in low density lipoprotein cholesterol concentrations and a 16.3% increase (95% CI 7.3 to −25.3) in those of high density lipoproteins. Fasting glucose concentrations and glucose tolerance test responses were unchanged. Fasting insulin concentrations fell substantially (–41.6%, 95% CI −23.4 to −59.8) with falls also being seen in insulin responses to glucose. Fasting C-peptide concentrations increased by 36.2% (95% CI 9.17 to 63.3), with no consistent effect on C-peptide responses to glucose.
Conclusions Dydrogesterone did not appear to oppose the potentially beneficial effects of oestradiol on insulin or either low or high density lipoproteins, making the combination with 17β-oestradiol a potentially useful option for postmenopausal women particularly those at risk of cardiovascular disease or diabetes mellitus.  相似文献   
14.
Objective To assess the efficacy of oral oestriol in the prevention of recurrent Urinary tract infections in elderly women.
Design Double-blind, randomised, parallel group, placebo controlled trial
Setting Urogynaecology Unit at King's College Hospital with some women recruited from the geriatric units of St. Pancras Hospital and Dulwich Hospital, London (UK).
Participants Seventy-two postmenopausal women older than 60 years of age (mean 73.2 years) suffering from recurrent urinary tract infections.
Intervention Oral oestriol (3 mg per day) or placebo for six months.
Main outcome measures Urinary tract infection rates.
Results The study was difficult to conduct because of its design and the age of the participants. Oral oestriol (3 mg per day) was not shown to be superior to placebo in the prevention of recurrent urinary tract infections, but both oestriol and placebo improved urinary symptoms during the trial.
Conclusion The power of the study might have been too low to detect a significant difference between the groups, or oral oestriol(3 mg per day) may have been either the wrong dose or the wrong route of administration for this indication.  相似文献   
15.
16.
17.
18.
The molecular mechanisms that coordinate cell morphogenesis with the cell cycle remain largely unknown. We have investigated this process in fission yeast where changes in polarized cell growth are coupled with cell cycle progression. The orb6 gene is required during interphase to maintain cell polarity and encodes a serine/threonine protein kinase, belonging to the myotonic dystrophy kinase/cot1/warts family. A decrease in Orb6 protein levels leads to loss of polarized cell shape and to mitotic advance, whereas an increase in Orb6 levels maintains polarized growth and delays mitosis by affecting the p34cdc2 mitotic kinase. Thus the Orb6 protein kinase coordinates maintenance of cell polarity during interphase with the onset of mitosis. orb6 interacts genetically with orb2, which encodes the Pak1/Shk1 protein kinase, a component of the Ras1 and Cdc42-dependent signaling pathway. Our results suggest that Orb6 may act downstream of Pak1/Shk1, forming part of a pathway coordinating cell morphogenesis with progression through the cell cycle.  相似文献   
19.
The Dama of South West Africa are a Negroid people living as a reproductive isolate in the desert and semi-desert areas of the north-west of the country. Until recent times a large proportion of them were held in bondage by the Khoikhoi (Hottentot) Nama, while the rest lived as hunter-gatherers in the mountains. This study and the work of Knussmann and Knussmann indicate that they are a Negro people, which probably has been cut off over a long period from contact with other Negroes. They have received very little genetic contribution from the Khoikhoi or the San (Bushmen). The results of this investigation of 24 blood genetic marker systems in a carefully selected random sample of Dama support these conclusions.  相似文献   
20.
Escherichia coli acetylvalyl (AcVal)-tRNA1Val became crosslinked to both yeast and spinach chloroplast ribosomes upon irradiation (300 nm) in the presence of poly(U2,G). Yields were 25-30% and 33%, respectively, compared to 45% for E. coli. Crosslinking occurred to the P site, only to the 40S subunit, and 90% of that was to the 18S rRNA. The crosslink could be photolyzed at 254 nm with the same first-order kinetics as for the E. coli ribosome complex previously studied. The AcVal-tRNA that split off could be crosslinked again when irradiated at 300 nm, showing that the crosslink was photoreversible. There was a strong codon specificity for crosslinking. With pG-U-U, 85% crosslinking was obtained after 20 min of irradiation; with G-U-A, only 3% crosslinking occurred. All of these properties are the same as those previously reported for the E. coli ribosome crosslink that occurs via cyclobutane dimer formation between the 5' anticodon base 5'-carboxymethoxyuridine-34 and cytidine-1400 of the 16S RNA. Cytidine-1400 is in the center of a 17-mer that has been almost totally conserved among the small subunit rRNAs of all species so far examined, including yeast. Crosslinking of tRNA in the same way to both yeast and E. coli ribosomes shows that there has been a functional conservation as well in this region of the small subunit rRNA. This region may be involved in some essential aspect of the decoding process that is common to both prokaryotic and eukaryotic protein synthesis systems.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号