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   1084篇
  免费   76篇
  国内免费   15篇
耳鼻咽喉   12篇
儿科学   109篇
妇产科学   61篇
基础医学   124篇
口腔科学   42篇
临床医学   123篇
内科学   233篇
皮肤病学   34篇
神经病学   46篇
特种医学   135篇
外科学   87篇
综合类   44篇
预防医学   43篇
眼科学   16篇
药学   40篇
中国医学   2篇
肿瘤学   24篇
  2021年   13篇
  2020年   14篇
  2019年   19篇
  2018年   16篇
  2017年   20篇
  2016年   21篇
  2015年   24篇
  2014年   31篇
  2013年   36篇
  2012年   30篇
  2011年   18篇
  2010年   51篇
  2009年   39篇
  2008年   31篇
  2007年   45篇
  2006年   24篇
  2005年   19篇
  2004年   18篇
  2003年   20篇
  2002年   17篇
  2001年   18篇
  2000年   19篇
  1999年   20篇
  1998年   46篇
  1997年   40篇
  1996年   37篇
  1995年   24篇
  1994年   33篇
  1993年   28篇
  1992年   14篇
  1991年   13篇
  1990年   19篇
  1989年   26篇
  1988年   22篇
  1987年   23篇
  1986年   12篇
  1985年   14篇
  1984年   17篇
  1983年   14篇
  1982年   24篇
  1981年   13篇
  1980年   23篇
  1979年   9篇
  1977年   14篇
  1976年   11篇
  1972年   9篇
  1971年   13篇
  1970年   15篇
  1969年   15篇
  1967年   10篇
排序方式: 共有1175条查询结果,搜索用时 15 毫秒
991.
992.
OBJECTIVE: To investigate the neuropsychological characteristics of patients diagnosed with mild cognitive impairment (MCI) with and without apathy. METHODS: A cohort of 245 MCI patients (mean age = 72 +/- 5.5 years; mean MMSE = 27.5 +/- 1.3) was divided into two subgroups according to their Apathy Inventory score and underwent an extensive neuropsychological battery. RESULTS: There were 94 (38.4%) patients with and 151 (61.6%) patients without apathy. At baseline the apathetic subgroup had a significantly lower total score on the free and cued selective reminding test (FCSR). Furthermore, the apathetic subgroup showed a significant deterioration in FCSR total recall score between baseline and the 1-year assessment. In conclusion, the presence of apathy in MCI patients is not associated with frontal task performance but with a higher degree of memory impairment.  相似文献   
993.
994.
995.
Cervical neural foramina: correlative anatomic and MR imaging study   总被引:2,自引:0,他引:2  
Accurate diagnosis of diseases affecting the cervical neural foramina with magnetic resonance (MR) imaging requires an appreciation of the normal anatomic appearance of the foramen. The MR appearance of the foramen was studied in cadavers and healthy volunteers and was correlated with cadaver cryomicrotome sections. With gradient-echo techniques, foraminal soft tissues are highlighted relative to adjacent bone, making gradient-echo images valuable for evaluating the overall size and contents of the neural foramina. Intravenously administered gadolinium DTPA produces enhancement of all foraminal soft tissues, including the dorsal root ganglion. The nerve roots do not enhance with Gd-DTPA. Gradient-echo pulse sequences and intravenous use of Gd-DTPA represent promising techniques for the evaluation of the cervical foramina.  相似文献   
996.
为了了解中老年人马拉松赛后心脏结构、功能和血清磷酸肌酸激酶及同功酶变化的特点,对参加加拿大国家马拉松赛的10名50—73岁的马拉松运动员进行观察并与10名50岁以下的马拉松运动员作了比较,发现50岁以上有训练的马拉松运动员有较好的血管调节功能和良好的心脏代偿能力。血清磷酸肌酸激酶同功酶的变化,反映了马拉松跑对老年人心脏的影响。  相似文献   
997.
998.
BACKGROUND: Trypanosoma cruzi, the cause of Chagas' disease, is often transmitted by transfusion in Latin America. Previous studies showed that at least 1 in 1000 eligible blood donors at the Los Angeles County+University of Southern California (LAC+USC) Medical Center Blood Bank had specific antibodies to T. cruzi. In June 1993, serologic screening of prospective allogeneic donors at epidemiologic risk for T. cruzi infection was begun voluntarily. STUDY DESIGN AND METHODS: The risk of T. cruzi infection in all eligible donors was assessed by questionnaire. At-risk donors were screened serologically for antibodies to T. cruzi with an enzyme immunoassay, and confirmatory testing was done with a radioimmunoprecipitation assay. RESULTS: During the 29-month study period 1311 (39.5%) of 3320 donors were judged to be at risk for T. cruzi infection. Seven donors (1/475) were reactive by an enzyme immunoassay, and six of these seven (1/ 553) were positive in a radioimmunoprecipitation assay. All radioimmunoprecipitation assay- positive donors had been born in countries in which Chagas' disease is endemic. One person in this group had received a transfusion in his homeland. CONCLUSION: These results demonstrate that a substantive proportion of eligible blood donors at our institution have antibodies specific for T. cruzi and that a commercially available assay can be used to detect these antibodies. Our data suggest that the risk of transmission of T. cruzi by transfusion could be eliminated by serologic testing limited to persons born in or transfused in countries in which Chagas' disease is endemic.  相似文献   
999.
1000.
Pancreatic necrosis: CT manifestations   总被引:2,自引:0,他引:2  
Pancreatic necrosis is a potential sequela of acute pancreatitis, which pathologically represents a collection of devitalized tissue. Appropriate therapeutic planning requires definition of this irreversibly damaged gland, the presence of which is not consistently diagnosed on the basis of clinical and laboratory data. Over an 18-month period, 22 patients with pancreatic necrosis were studied by one or more computed tomographic (CT) examinations. Retrospective analysis showed the findings to vary with the developmental stage of the necrotizing process. During the acute phase, there was considerable morphologic overlap of necrosis and pancreatic phlegmon. Typical findings were seen in the subacute and chronic stages and included diffuse enlargement of the gland with largely decreased central density. A thick, smooth surrounding rim produced a characteristic saclike configuration. CT-guided aspiration for culture material was performed in four patients with suspected superinfection. Negative gram stain and culture results in two patients allowed surgery to be performed on a more elective basis.  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