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   5718篇
  免费   485篇
  国内免费   9篇
耳鼻咽喉   45篇
儿科学   126篇
妇产科学   216篇
基础医学   848篇
口腔科学   95篇
临床医学   552篇
内科学   1289篇
皮肤病学   155篇
神经病学   414篇
特种医学   267篇
外国民族医学   5篇
外科学   797篇
综合类   61篇
一般理论   6篇
预防医学   505篇
眼科学   52篇
药学   331篇
中国医学   11篇
肿瘤学   437篇
  2022年   39篇
  2021年   81篇
  2020年   44篇
  2019年   71篇
  2018年   82篇
  2017年   68篇
  2016年   74篇
  2015年   76篇
  2014年   117篇
  2013年   163篇
  2012年   255篇
  2011年   283篇
  2010年   154篇
  2009年   140篇
  2008年   267篇
  2007年   270篇
  2006年   224篇
  2005年   243篇
  2004年   247篇
  2003年   239篇
  2002年   213篇
  2001年   216篇
  2000年   224篇
  1999年   162篇
  1998年   103篇
  1997年   85篇
  1996年   67篇
  1995年   52篇
  1994年   64篇
  1993年   49篇
  1992年   143篇
  1991年   110篇
  1990年   120篇
  1989年   116篇
  1988年   115篇
  1987年   120篇
  1986年   88篇
  1985年   94篇
  1984年   79篇
  1983年   65篇
  1981年   40篇
  1979年   59篇
  1978年   45篇
  1974年   50篇
  1973年   50篇
  1972年   42篇
  1971年   47篇
  1969年   38篇
  1968年   35篇
  1967年   45篇
排序方式: 共有6212条查询结果,搜索用时 15 毫秒
11.
The procoagulant response of cytomegalovirus infected endothelial cells.   总被引:6,自引:0,他引:6  
The report describes the effect of an in vitro infection of human umbilical vein endothelial cells with human Cytomegalovirus (CMV). The parameters studied are cellular procoagulant activity, secretion of plasminogen activator inhibitor (PAI-1) and urokinase-type plasminogen activator (u-PA), activation and internalization of factor X and Merocyanine 540 staining. The infection does not result in an increase in PAI-1 and u-PA secretion, but it brings about a procoagulant response, which is relatively rapid compared to the tissue factor mediated response induced by inflammatory mediators. The time course and the coagulation factor dependency suggest a facilitated interaction of coagulation factors on the surface of infected cells. Chromogenic activity measurements after the addition of purified factor X and electron microscopic examination of the cells after addition of colloidal gold-factor X conjugates both point to an internalization of factor X and/or Xa after interaction with the endothelial cell surface. Merocyanine 540 staining suggests that CMV infection leads to membrane perturbations.  相似文献   
12.
13.
OBJECTIVE: To determine the separate and interactive effects of age, phase of the menstrual cycle, menopausal hormone status, body fat mass, and regional fat distribution on glucose tolerance in healthy women. DESIGN: Retrospective study. SETTING: The Baltimore Longitudinal Study of Aging. PATIENTS: Two hundred sixty healthy women aged 22-89 years. MEASUREMENTS: Plasma levels of estradiol and progesterone, body mass index (BMI), waist-to-hip ratio (WHR), and plasma glucose values in the fasting state (FPG) as well as 120 minutes after 40 gm/m2 of oral glucose (G120) were measured for each participant. RESULTS: We found a progressive decline in oral glucose tolerance of 0.4 mM (6.7 mg/dL)/decade at G120) in women from early to late adult years, with no relationship to phase of the menstrual cycle and no abrupt change associated with the menopause. Multiple regression analysis revealed significant, independent effects of BMI and WHR on FPG and G120. The influence of age (P less than 0.01) on G120 was stronger than that of the BMI or WHR (P less than 0.05). There was no significant relationship between the levels of endogenous sex hormones and glucose tolerance after adjustments for age, BMI, and WHR. However, women taking oral contraceptives, but not those receiving postmenopausal replacement therapy, did exhibit mildly elevated G120 values. CONCLUSIONS: Age per se, and to a lesser extent BMI and WHR, but not levels of endogenous sex steroids, contribute to the physiological decline in glucose tolerance in older women.  相似文献   
14.
15.
16.
The clinical presentation of SARS is nonspecific and diagnostic tests do not provide accurate results early in the disease course. Initial diagnosis remains reliant on clinical assessment. To identify features of the clinical assessment that are useful in SARS diagnosis, the exposure status and the prevalence and timing of symptoms, signs, laboratory and radiographic findings were determined for all adult patients admitted with suspected SARS during the Toronto SARS outbreak. Findings were compared between patients with laboratory-confirmed SARS and those in whom SARS was excluded by laboratory or public health investigation. Of 364 cases, 273 (75%) had confirmed SARS, 30 (8%) were excluded, and 61 (17%) remained indeterminate. Among confirmed cases, exposure occurred in the healthcare environment (80%) or in the households of affected patients (17%); community or travel-related cases were rare (<3%). Fever occurred in 97% of patients by the time of admission. Respiratory findings including cough, dyspnea and pulmonary infiltrates evolved later and were present in only 59, 37 and 68% of patients, respectively, at admission. Direct exposure, fever on the first day of illness, and elevated temperature, pulmonary infiltrates, lymphopenia and thrombocytopenia at admission were associated with confirmed cases. Rhinorrhea, sore throat, and an elevated neutrophil count at admission were associated with excluded cases. In the absence of fever or significant exposure, SARS is unlikely. Other clinical, laboratory and radiographic findings further raise or lower the likelihood of SARS and provide a rational basis for estimating the likelihood of SARS and directing initial management.  相似文献   
17.
18.
19.
20.
In a retrospective study of 137 biopsy specimens of skin from 137 patients (69 men and 68 women) that had been obtained between 1972 and 1989 at our institution and that had perivascular and periappendageal lymphocytic infiltrates characteristic of those described as benign lymphocytic infiltrate (BLI), we determined the specificity of the histologic diagnosis and the correlation with clinical data. The final diagnoses, based on clinical and laboratory data and histologic findings, were BLI (59), possible BLI (7), lupus erythematosus (LE) (12), possible LE (7), procainamide-induced LE (1), insect bites (9), possible insect bites (3), polymorphous light eruption (4), lymphocytoma (4), urticaria (4), and indeterminate or miscellaneous diagnoses (27). BLI is a clinical and histologic syndrome that can be heterogeneous in origin. We recommend careful evaluation to exclude other disorders such as LE, polymorphous light eruption, lymphocytoma, and insect bites. Direct immunofluorescence microscopy and immunophenotypic studies may help distinguish BLI from LE.  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