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   7948篇
  免费   729篇
  国内免费   22篇
耳鼻咽喉   64篇
儿科学   310篇
妇产科学   270篇
基础医学   899篇
口腔科学   160篇
临床医学   819篇
内科学   1866篇
皮肤病学   162篇
神经病学   874篇
特种医学   338篇
外国民族医学   1篇
外科学   1151篇
综合类   286篇
一般理论   3篇
预防医学   595篇
眼科学   65篇
药学   391篇
肿瘤学   445篇
  2021年   78篇
  2018年   87篇
  2016年   78篇
  2015年   104篇
  2014年   131篇
  2013年   184篇
  2012年   272篇
  2011年   292篇
  2010年   170篇
  2009年   161篇
  2008年   288篇
  2007年   298篇
  2006年   269篇
  2005年   254篇
  2004年   273篇
  2003年   308篇
  2002年   276篇
  2001年   257篇
  2000年   293篇
  1999年   241篇
  1998年   144篇
  1997年   107篇
  1996年   111篇
  1995年   91篇
  1994年   96篇
  1993年   105篇
  1992年   222篇
  1991年   238篇
  1990年   212篇
  1989年   204篇
  1988年   235篇
  1987年   218篇
  1986年   212篇
  1985年   192篇
  1984年   178篇
  1983年   154篇
  1982年   99篇
  1981年   92篇
  1980年   81篇
  1979年   135篇
  1978年   83篇
  1977年   90篇
  1976年   81篇
  1975年   68篇
  1974年   96篇
  1973年   91篇
  1972年   87篇
  1971年   77篇
  1970年   71篇
  1969年   73篇
排序方式: 共有8699条查询结果,搜索用时 15 毫秒
1.
2.
Sleep is a vital, highly organized process regulated by complex systems of neuronal networks and neurotransmitters. Sleep plays an important role in the regulation of central nervous system and body physiologic functions. Sleep architecture changes with age and is easily susceptible to external and internal disruption. Reduction or disruption of sleep can affect numerous functions varying from thermoregulation to learning and memory during the waking state.  相似文献   
3.
The dermal absorption of niclosamide, a drug shown to prevent Schistosomiasis by blocking the dermal penetration of cercariae, has been examined in Sinclair minipigs and rats. Radioactivity in the urine and feces collected daily for 7 days after application of 14C-niclosamide accounted for less than 2 per cent and 10 per cent of the labelled compound applied to pig and rat skin, respectively. Approximately 20 per cent of the radioactivity from the dose solution was recovered on the skin excised from the area of application in both minipigs and rats. No radioactivity was detected in organs removed from the pig 7 days after application of radiolabelled drug while less than 6 per cent of the dose could be accounted for in the rat organs/carcass. Radioactivity in swine blood, removed 0.5, 1, 2, 4 and at 24 h intervals after dosing, was at or below three times background in all of the samples. Total recovery of the applied radioactivity was 78 per cent in pigs and 57 per cent in rats. These studies indicate that niclosamide is very poorly absorbed after dermal application. The results are consistent with earlier comparative studies showing that dermal penetration of xenobiotics in rats is generally higher than in swine.  相似文献   
4.
A 68 year-old woman presented with a two-week history of amaurosis fugax, ipsilateral fronto-temporal headache and jaw claudication suggesting carotid giant cell arteritis. However, this syndrome proved to be due to atherosclerosis causing complete occlusion of the external carotid artery at its origin and narrowing of the internal carotid artery. Combined external and internal carotid endarterectomy relieved the symptoms. The symptom complex of temporal arteritis may be rarely mimicked by carotid atherosclerotic occlusive disease.  相似文献   
5.
In the present study, we address the role of the gene for catechol-O-methyltransferase (COMT), a key modulator of dopaminergic and noradrenergic neurotransmission, in the genetic predisposition to obsessive-compulsive disorder (OCD). We show that a common functional allele of this gene, which results in a 3- to 4-fold reduction in enzyme activity, is significantly associated in a recessive manner with susceptibility to OCD, particularly in males. This association is further supported by psychiatric evaluation of patients who carry microdeletions encompassing the comt gene. The mechanism underlying this sex-selective association remains to be defined and may include a sexual dimorphism in COMT activity, although close linkage with a nearby disease susceptibility locus cannot be excluded at this point.  相似文献   
6.
J M Goldman  D J Barnes    D V Pohl 《Thorax》1990,45(1):76
A case of obstructive sleep apnoea is reported that was caused by a dermoid cyst of the floor of the mouth and cured by surgery.  相似文献   
7.
Infertility in women and moderate alcohol use.   总被引:16,自引:2,他引:14       下载免费PDF全文
OBJECTIVE. The purpose of this study was to investigate the relationship between moderate alcohol intake and fertility. METHODS. Interviews were conducted with 3833 women who recently gave birth and 1050 women from seven infertility clinics. The case subjects were categorized based on the infertility specialist's assignment of the most likely cause of infertility: ovulatory factor, tubal disease, cervical factor, endometriosis, or idiopathy. Separate logistic regression models were used to assess the relationship between alcohol use and each type of infertility, adjusted for age, infertility center, cigarette smoking, caffeine use, number of sexual partners, use of an intrauterine device (for tubal disease), and body mass index and exercise (for ovulatory factor). RESULTS. We found an increase in infertility, due to ovulatory factor or endometriosis, with alcohol use. The odds ratio for ovulatory factor was 1.3 (95% confidence interval [CI] = 1.0, 1.7) for moderate drinkers and 1.6 (95% CI = 1.1, 2.3) for heavier drinkers, compared with nondrinkers. The risk of endometriosis was roughly 50% higher in case subjects with any alcohol intake than in control subjects (OR = 1.6, 95% CI = 1.1, 2.3, at moderate levels; OR = 1.5, 95% CI = 0.8, 2.7, at heavier levels). CONCLUSIONS. Moderate alcohol use may contribute to the risk of specific types of infertility.  相似文献   
8.
9.
Retrospectively we analyzed the histocompatibility data and clinical results of bone marrow transplantation in 51 patients who received marrow from unrelated donors (UD) from 1977 to 1987 at one of four UK BMT centers. We compared the results with those obtained in 51 transplants carried out at the same centers using HLA-identical (ID) sibling donors. Of the UD/recipient pairs 32 (63%) were serologically identical for HLA A, B, and DR antigens, and 37% showed varying degrees of mismatch. UD-BMT primary diagnoses were: severe aplastic anemia or Fanconi's anemia (n = 17), acute leukemia (n = 11), chronic myeloid leukemia (n = 21), and other conditions (n = 2). T cell depletion of the graft was associated with a significant improvement in survival in both UD and ID-BMT. Graft failure was more common in recipients of UD than of ID transplants (13 [25%] vs. 5 [10%] P = 0.05) but there was no significant difference in the frequency of acute or chronic graft-versus-host disease. Actuarial survival was superior for recipients of ID transplants (UD vs. ID: 49% vs. 78%, respectively, at 3 months; 32% vs. 63% at one year). Reduced survival for recipients of UD-BMT was confirmed in case control regression analysis (relative risk 3.0, P = 0.01). Nevertheless in patients whose only alternative is a partially mismatched family donor we think that UD-BMT is justified.  相似文献   
10.
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