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   2550251篇
  免费   197651篇
  国内免费   3869篇
耳鼻咽喉   34593篇
儿科学   84211篇
妇产科学   72222篇
基础医学   370132篇
口腔科学   74540篇
临床医学   232331篇
内科学   492732篇
皮肤病学   55181篇
神经病学   206169篇
特种医学   98653篇
外国民族医学   713篇
外科学   374839篇
综合类   59471篇
现状与发展   5篇
一般理论   1063篇
预防医学   205347篇
眼科学   58355篇
药学   190813篇
  10篇
中国医学   4481篇
肿瘤学   135910篇
  2018年   25217篇
  2016年   21626篇
  2015年   25057篇
  2014年   34557篇
  2013年   53076篇
  2012年   71744篇
  2011年   76230篇
  2010年   44688篇
  2009年   42883篇
  2008年   72402篇
  2007年   76918篇
  2006年   77248篇
  2005年   75309篇
  2004年   73491篇
  2003年   70435篇
  2002年   68594篇
  2001年   113900篇
  2000年   117241篇
  1999年   99580篇
  1998年   27906篇
  1997年   25388篇
  1996年   25665篇
  1995年   24727篇
  1994年   23122篇
  1993年   21779篇
  1992年   81541篇
  1991年   79636篇
  1990年   77692篇
  1989年   75249篇
  1988年   69831篇
  1987年   68726篇
  1986年   65605篇
  1985年   62986篇
  1984年   47513篇
  1983年   41404篇
  1982年   24472篇
  1981年   22063篇
  1980年   20787篇
  1979年   45468篇
  1978年   32304篇
  1977年   27222篇
  1976年   25555篇
  1975年   27176篇
  1974年   33139篇
  1973年   32205篇
  1972年   29950篇
  1971年   28102篇
  1970年   26122篇
  1969年   24744篇
  1968年   22723篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
We describe the simple adaptation of a standard fluorescent microscope for illumination using a 'Royal Blue' Luxeon light emitting diode (LED) and demonstrate that this form of illumination is suitable for the detection of auramine O stained Mycobacterium spp. The low cost, low power consumption, safety and reliability of LEDs makes them attractive alternatives to mercury vapour lamps.  相似文献   
102.
OBJECTIVE: Gelastic seizures are a frequent and well established manifestation of the epilepsy associated with hypothalamic hamartomas. The scalp EEG recordings very seldom demonstrate clear spike activity and the information about the ictal epilepsy dynamics is limited. In this work, we try to isolate epileptic rhythms in gelastic seizures and study their generators. METHODS: We extracted rhythmic activity from EEG scalp recordings of gelastic seizures using decomposition in independent components (ICA) in three patients, two with hypothalamic hamartomas and one with no hypothalamic lesion. Time analysis of these rhythms and inverse source analysis was done to recover their foci of origin and temporal dynamics. RESULTS: In the two patients with hypothalamic hamartomas consistent ictal delta (2-3 Hz) rhythms were present, with subcortical generators in both and a superficial one in a single patient. The latter pattern was observed in the patient with no hypothalamic hamartoma visible in MRI. The deep generators activated earlier than the superficial ones, suggesting a consistent sub-cortical origin of the rhythmical activity. CONCLUSIONS: Our data is compatible with early and brief epileptic generators in deep sub-cortical regions and more superficial ones activating later. SIGNIFICANCE: Gelastic seizures express rhythms on scalp EEG compatible with epileptic activity originating in sub-cortical generators and secondarily involving cortical ones.  相似文献   
103.
In rare cases the usage of the internal thoracic vessels as recipient vessels in reconstructive surgery of the head and neck region with free tissue transfer is a challenging but valid alternative if local recipient vessels are unusable.  相似文献   
104.
AIM: The intention was to investigate cerebrospinal fluid pressure (CSFP) and volume of cerebrospinal fluid (CSF) drained during and after thoracic- and thoracoabdominal aneurysm repair. The findings were related to the occurrence of postoperative neurologic deficits. METHODS: Twenty-nine patients (12 with thoracic and 17 with thoracoabdominal aortic aneurysm) were operated without shunting or extracorporeal circulation. For monitoring of CSFP an intrathecal catheter was placed in all patients. The volume of CSF withdrawn intraoperatively, on the day of operation as well as on the 1st and 2nd postoperative day was recorded. RESULTS: Twenty-six patients had no postoperative neurologic sequelae. One patient had postoperative paraplegia while 2 had paraparesis. The three patients with neurologic sequelae had higher CSFP intraoperatively than those without neurologic symptoms (P=0.04). Median CSFP during aortic cross-clamping was 19 mmHg and 10 mmHg and the median volumes of CSF drained on the day of operation 210 and 85 mL in the two groups, respectively. There was a significant positive correlation between CSFP and central venous pressure. CONCLUSIONS: A higher intraoperative CSFP was observed in patients with neurologic sequelae following thoracic- and thoracoabdominal aneurysm repair. Further, there was a tendency of higher volumes of CSF drained in this group of patients. Although, the series is too small to allow firm conclusions, it supports the view that CSFP monitoring and drainage is beneficial during thoracic- and thoracoabdominal aneurysm repair.  相似文献   
105.
Many recent efforts in the field of community psychology have been dedicated to moving from values to action in incorporating diversity into our work. An essential aspect of this goal is designing research that provides opportunities for underrepresented perspectives to be heard. The voices of refugee women, in particular, are not typically incorporated in research, planning for service provision, and policy design. This article explores methodological challenges involved in conducting research with refugee women who are marginalized both within broader U.S. contexts and within their own communities. Six guiding principles are presented: 1) develop strategies for involving marginalized refugee women; 2) consider the advantages and limitations of quantitative and qualitative methodologies and be innovative about combining them; 3) prepare for extensive time and effort for quantitative measure construction; 4) consider gendered decision‐making structures in the lives of refugee women and their potential impact on the research process; 5) plan for refugee women's common triple burden of working outside of the home, managing their households, and adjusting to life in a new country; and 6) attend to refugee women's cultural norms about and unfamiliarity with the interview process. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 721–739, 2004.  相似文献   
106.
107.
108.
109.
110.
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