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   118864篇
  免费   6950篇
  国内免费   1581篇
耳鼻咽喉   1576篇
儿科学   2970篇
妇产科学   4107篇
基础医学   18326篇
口腔科学   3608篇
临床医学   9273篇
内科学   21612篇
皮肤病学   2437篇
神经病学   8001篇
特种医学   4018篇
外国民族医学   3篇
外科学   16751篇
综合类   5213篇
一般理论   34篇
预防医学   8680篇
眼科学   2818篇
药学   10197篇
中国医学   818篇
肿瘤学   6953篇
  2021年   983篇
  2019年   1047篇
  2018年   1609篇
  2017年   1167篇
  2016年   1198篇
  2015年   1447篇
  2014年   1886篇
  2013年   2440篇
  2012年   3546篇
  2011年   3800篇
  2010年   2289篇
  2009年   2049篇
  2008年   3383篇
  2007年   3615篇
  2006年   3601篇
  2005年   3166篇
  2004年   2978篇
  2003年   2774篇
  2002年   2631篇
  2001年   6730篇
  2000年   6921篇
  1999年   5695篇
  1998年   1829篇
  1997年   1377篇
  1996年   936篇
  1995年   862篇
  1992年   3728篇
  1991年   3806篇
  1990年   3549篇
  1989年   3552篇
  1988年   3428篇
  1987年   3277篇
  1986年   3090篇
  1985年   2967篇
  1984年   2048篇
  1983年   1792篇
  1982年   985篇
  1979年   1909篇
  1978年   1184篇
  1977年   986篇
  1976年   918篇
  1975年   1191篇
  1974年   1358篇
  1973年   1413篇
  1972年   1357篇
  1971年   1247篇
  1970年   1137篇
  1969年   1121篇
  1968年   1024篇
  1967年   897篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
The involuntary hospitalisation of psychiatric patients continues to be a controversial issue. All patients certified and admitted to Sterkfontein Hospital under Sections 9 and 12 of the Mental Health Act, No. 18 of 1973, over a 4-week period were surveyed. Almost 40% were admitted as urgent certifications. The majority of the patients in the sample were black, single, urban and had either primary or limited high school education. Most patients had been referred from academic/teaching and provincial hospitals. The average duration of hospital stay was 7.2 weeks, with only 1 patient eventually being transferred to a ward for chronic patients within the hospital, which suggests that Sterkfontein Hospital functions largely as an acute psychiatric facility. There was a discrepancy of approximately 30% between the assessments of the certifying and ward doctors, probably as a result of differing uses of terminology. Not only are more community psychiatric services needed, but communication between psychiatry and the other medical disciplines should be improved.  相似文献   
82.
83.
84.
Prolongation of the action potential duration of dorsal root ganglion (DRG) neurons by low (nM) concentrations of opioids occurs through activation of excitatory opioid receptors that are positively coupled via Gs regulatory protein to adenylate cyclase. Previous results suggested GM1 ganglioside to have an essential role in regulating this excitatory response, but not the inhibitory (APD-shortening) response to higher (μM) opioid concentrations. Furthermore, it was proposed that synthesis of GM1 is upregulated by prolonged activation of excitatory opioid receptor functions. To explore this possibility we have utilized cultures of hybrid F11 cells to carry out closely correlated electrophysiological and biochemical analyses of the effects of chronic opioid treatment on a homogeneous population of clonal cells which express many functions characteristic of DRG neurons. We show that chronic opioid exposure of F11 cells does, in fact, result in elevated levels of GM1 as well as cyclic adenosine monophosphate (AMP), concomitant with the onset of opioid excitatory supersensitivity as manifested by naloxone-evoked decreases in voltage-dependent membrane K+ currents. Such elevation of GM1 would be expected to enhance the efficacy of excitatory opioid receptor activation of the Gs/adenylate cyclase/cyclic AMP system, thereby providing a positive feedback mechanism that may account for the remarkable supersensitivity of chronic opioid-treated neurons to the excitatory effects of opioid agonists as well as antagonists. These in vitro findings may provide novel insights into the mechanisms underlying naloxone-precipitated withdrawal syndromes and opioid-induced hyperalgesia after chronic opiatf addiction in vivo. © 1995 Wiley-Liss, Inc.  相似文献   
85.
86.
Clinicopathologic correlation of pigmented epiretinal membranes   总被引:1,自引:0,他引:1  
We performed clinicopathologic correlation on ten surgically removed pigmented epiretinal membranes causing macular pucker. All cases occurred in eyes with existing retinal holes or tears, including eight cases of macular pucker after previous retinal detachment. These cases probably represented a limited form of proliferative vitreoretinopathy. All membranes contained pigment epithelial cells with polarity, basement membrane, and melanosomes. Cytoplasmic melanin granules accounted for the clinical feature of pigmentation in these eyes.  相似文献   
87.
88.
89.
Changes in semen parameters are presented for 4708 patients treated for infertility. The largest group comprised patients with oligoasthenozoospermia of various grades (57.7%). Improvement in the seminal state was noted in 70.3%. The percentage of achieved normospermia increased proportionally to the initial semen state. Pregnancy rate also increased proportionally to the initial seminal state. Among the patients' wives 20.4% conceived: 28.2% of these pregnancies had occurred after having achieved normospermia, while in 71.8% the seminal states were still below the accepted normal values.  相似文献   
90.
We report a series of 33 consecutive hospitalized geriatric diabetic patients who were referred for evaluation of diabetic nephropathy, defined as proteinuria greater than or equal to 1 g/d (1,000 mg/24 h) or a serum creatinine concentration greater than or equal to 177 mumol/d (greater than or equal to 2 mg/dL). The study population was 60 years old or older (mean age, 68 +/- 6 years), was comprised mainly of women (24 of 33, 72.7%), and was predominantly black (25 of 33, 75.8%). All patients had type II diabetes. A family history of diabetes in parent or sibling was elicited in 24 (72.7%) patients. There were eight patients undergoing maintenance hemodialysis and 25 with less severe nephropathy (mean proteinuria, 2.7 g/d [2,700 mg/24 h]; mean creatinine clearance, 0.57 mL-s [34 mL/min]). Cardiac disorders were noted in the majority of patients: congestive failure in 20 (60.6%), myocardial infarction in eight (24.2%), and active angina in five (15.2%). Other comorbid diseases were present in both hemodialysis patients and the subset of nondialyzed azotemic-proteinuric patients, and consisted of peripheral neuropathy in 31 (93.9%), gastroparesis in 16 (48.5%), retinopathy in 28 (84.8%), and legal blindness in 11 (33%). We conclude that geriatric diabetic nephropathy in type II diabetes is similar in presentation and severity of comorbid extrarenal complications to the syndrome described in younger adults. This inference must be tempered by both the small size and the limitation imposed by the demographics of the study population, which is predominantly composed of black patients receiving treatment at inner city hospitals.  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