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   2054984篇
  免费   145946篇
  国内免费   3138篇
耳鼻咽喉   29390篇
儿科学   62355篇
妇产科学   57334篇
基础医学   295746篇
口腔科学   59736篇
临床医学   176365篇
内科学   401688篇
皮肤病学   42776篇
神经病学   159803篇
特种医学   80471篇
外国民族医学   439篇
外科学   324707篇
综合类   41698篇
现状与发展   2篇
一般理论   511篇
预防医学   145088篇
眼科学   47395篇
药学   158657篇
  3篇
中国医学   4309篇
肿瘤学   115595篇
  2018年   19148篇
  2016年   16394篇
  2015年   18922篇
  2014年   25925篇
  2013年   39000篇
  2012年   53466篇
  2011年   56791篇
  2010年   33664篇
  2009年   31899篇
  2008年   55340篇
  2007年   59276篇
  2006年   60359篇
  2005年   58797篇
  2004年   56780篇
  2003年   54855篇
  2002年   53984篇
  2001年   102613篇
  2000年   105862篇
  1999年   89317篇
  1998年   23213篇
  1997年   20631篇
  1996年   20845篇
  1995年   19560篇
  1994年   18423篇
  1993年   17039篇
  1992年   70365篇
  1991年   68409篇
  1990年   66952篇
  1989年   65199篇
  1988年   60344篇
  1987年   58877篇
  1986年   55751篇
  1985年   53266篇
  1984年   38937篇
  1983年   33506篇
  1982年   18864篇
  1981年   16603篇
  1979年   35936篇
  1978年   24840篇
  1977年   21448篇
  1976年   19588篇
  1975年   21543篇
  1974年   25691篇
  1973年   24477篇
  1972年   23371篇
  1971年   21872篇
  1970年   20541篇
  1969年   19688篇
  1968年   18259篇
  1967年   16151篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Choledochojejunostomy (CJS) is commonly used for biliary reconstruction in liver transplantation for primary sclerosing cholangitis (PSC). We alternatively performed choledochoduodenostomy (CDS) and side-to-side choledochodocholedochstomy in a large cohort of patients. Fifty-one patients with PSC, transplanted between 1988 and 2000, were analyzed retrospectively. Biliary reconstruction was CDS in 25 (49%), CJS in 20 (39%) and CC in 6 transplantations (12%). Biliary leaks occurred in the early follow-up (< or =41 days) only in CDS patients (20%). However, in the late follow-up (>4 months), stricturing of anastomosis was found once in CDS (4%) and CJS (5%). Later (>9 months), intrahepatic bile duct strictures were diagnosed in four CDS (16%), one CJS (5%) and one CC (17%) patient(s). In 48% of CDS (12/25), 60% of CJS (12/20) and 17% of CC (1/6) at least one incidence of cholangitis was observed. Overall, biliary complication rates were significantly higher in CDS (40%) than CJS (10%) and CC (17%); of those none in CC and 12% in CDS were anastomosis-related. Graft/patient survival showed no significant differences among groups. Based on our results we consider CJS the standard method for biliary reconstruction in PSC; however, in selected cases where CJS is difficult to accomplish because of previous surgery or for retransplantation, CDS may present an alternative technique.  相似文献   
62.
BACKGROUND: Psychotic symptoms in Alzheimer disease (AD+P) identify a heritable phenotype associated with more rapid cognitive decline. The authors have proposed that AD+P is itself a composite of a misidentification and a paranoid subtype with increased cognitive impairment restricted to the misidentification type. Most prior studies of the clinical correlates of AD+P have been limited, however, by the inclusion of prevalent cases. METHODS: Subjects with possible or probable AD or mild cognitive impairment (MCI) without psychosis at study entry were assessed at the time of initial presentation and then annually. Psychotic symptoms were assessed using the CERAD Behavioral Rating Scale. Survival analyses used Cox proportional hazard models with time-dependent covariates to examine the predictors of psychosis onset. RESULTS: A total of 288 subjects completed at least one follow-up examination. Mean duration of follow-up was 22.1 months. The incidence of psychosis was 0.19 per person-year. Cognitive impairment was associated with onset of psychosis, largely as a result of its association with onset of the misidentification, but not the paranoid, subtype. Including psychotropic medication use in the model revealed an association of antidepressant use with the onset of psychosis. This latter association appeared to arise from an underlying association between depression and the risk of psychosis onset rather than from antidepressant treatment. CONCLUSION: These findings are consistent with the hypothesis that the misidentification and the paranoid subtypes each define a more biologically homogeneous group than AD+P as a whole. Further exploration of the relationship between depressive symptoms and psychosis in patients with AD is warranted.  相似文献   
63.
64.
65.
66.
For patients who receive a liver transplant (LTX) for alcoholic liver disease (ALD), investigators are focusing beyond survival to determine specific alcohol use outcomes. Studies suggest the use of alcohol ranges from 8 to 22% for the first post-transplant year with cumulative rates reaching 30 to 40% by 5 years following transplantation. Yet while investigators are interested in determining specific rates of alcohol use and predictors of use, only three studies since 1990 have been prospective. In 1998, we began a prospective study of post-LTX alcohol consumption in ALD recipients using multiple repeated measures of alcohol use. After 5 years of follow-up, we found that 22% had used any alcohol by the first year and 42% had a drink by 5 years. By 5 years, 26% drank at a heavier use (binge) pattern and 20% drank in a frequent pattern. In a univariate model, predictors of alcohol use included pre-transplant length of sobriety, a diagnosis of alcohol dependence, a history of other substance use, and prior alcohol rehabilitation.  相似文献   
67.
Turboprop: improved PROPELLER imaging.   总被引:1,自引:0,他引:1  
A variant of periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) MRI, called turboprop, is introduced. This method employs an oscillating readout gradient during each spin echo of the echo train to collect more lines of data per echo train, which reduces the minimum scan time, motion-related artifact, and specific absorption rate (SAR) while increasing sampling efficiency. It can be applied to conventional fast spin-echo (FSE) imaging; however, this article emphasizes its application in diffusion-weighted imaging (DWI). The method is described and compared with conventional PROPELLER imaging, and clinical images collected with this PROPELLER variant are shown.  相似文献   
68.
69.
70.
We report the case of a 38-year-old woman who presented with chronic lower abdominal pain. Her past medical history included a splenectomy due to abdominal trauma. Ultrasound examination revealed four pelvic tumors which, upon laparotomy, were found to be the result of splenosis. Approximately 100 cases of splenosis have been reported but only a minority of them have been published in the gynecological literature. Our case indicates that those involved in pelvic scanning (even of asymptomatic women) and/or treating those complaining of lower abdominal pain or presenting with pelvic tumors should be aware of splenosis as a possible diagnosis.  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