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   1278414篇
  免费   92884篇
  国内免费   1991篇
耳鼻咽喉   18214篇
儿科学   42309篇
妇产科学   37872篇
基础医学   187227篇
口腔科学   35414篇
临床医学   108237篇
内科学   251928篇
皮肤病学   26539篇
神经病学   99332篇
特种医学   50109篇
外国民族医学   366篇
外科学   197802篇
综合类   26522篇
现状与发展   1篇
一般理论   301篇
预防医学   92776篇
眼科学   29071篇
药学   97890篇
  1篇
中国医学   2498篇
肿瘤学   68880篇
  2018年   11871篇
  2015年   11687篇
  2014年   16057篇
  2013年   24448篇
  2012年   33660篇
  2011年   36050篇
  2010年   21274篇
  2009年   20072篇
  2008年   35067篇
  2007年   38048篇
  2006年   38629篇
  2005年   37903篇
  2004年   36483篇
  2003年   35429篇
  2002年   34975篇
  2001年   58148篇
  2000年   59645篇
  1999年   50738篇
  1998年   14249篇
  1997年   12825篇
  1996年   13088篇
  1995年   12357篇
  1994年   11769篇
  1993年   10871篇
  1992年   40999篇
  1991年   40380篇
  1990年   39907篇
  1989年   38720篇
  1988年   36119篇
  1987年   35359篇
  1986年   33735篇
  1985年   32146篇
  1984年   23933篇
  1983年   20834篇
  1982年   12382篇
  1981年   10933篇
  1980年   10211篇
  1979年   22650篇
  1978年   15880篇
  1977年   13735篇
  1976年   12973篇
  1975年   14203篇
  1974年   16689篇
  1973年   16083篇
  1972年   15322篇
  1971年   14230篇
  1970年   13220篇
  1969年   12735篇
  1968年   11981篇
  1967年   10483篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
102.
Background The appearance of eosinophils is a hallmark sign of the allergic late-phase response (LPR). Eosinophil cationic protein (ECP), a readily measurable product released from activated eosinophils, has so far not been evaluated in the ocular LPR. Objective Two sets of trials were performed in order to investigate changes of local and systemic eosinophil activity and their possible link with symptoms and hyper-reactivity in the allergic LPR in the eye. Methods In the first experiment, ECP was analysed in tears and serum and the clinical reaction was evaluated during a 72-h time–course after a single, high-dose allergen challenge out of season in one eye of 15 pollen-sensitized volunteers. In a second experiment, the hypothesis of an increased clinical response to an allergen challenge in an eye that had been provoked with allergen 48h previously was tested in nine sensitized individuals. Results In the first experiment, symptoms at 10 min and 2, 4, 6, 8 and 24 h significantly exceeded base line scores of the challenged eyes. Tear ECP was significantly elevated in challenged eyes compared to contralateral eyes at 6, 8 and 24 h. In addition, symptoms and ECP release correlated significantly at the 24-h evaluation. Serum ECP remained unchanged throughout the study period. In the second experiment, conjunctival hyperreactivity 48h after an allergen challenge was not confirmed. Conclusion ECP secretion occurs in the experimental ocular LPR and is in part associated with the magnitude of the clinical reaction, which suggests a truly pathogenic role of the activated eosinophil in pollen-induced allergic conjunctivitis.  相似文献   
103.
104.
105.
106.
107.
108.
109.
Transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (TES) of the human motor cortex produce a silent period (SP) following motor evoked potentials (MEPs). The early part of the SP can be explained by decreased alpha motor neuron excitability, whereas the late part is presumably due to suprasegmental mechanisms. In order to determine the level of the suprasegmental contribution to the generation of SPs, we recorded excitatory and inhibitory responses to TMS, TES, and percutaneous electrical brainstem stimulation (PBS) in the voluntarily activated first dorsal interosseous muscle of the hand. Stimulus intensities were set so that PBS and TES induced MEPs with areas equal to or larger than those of MEPs obtained with TMS. This procedure revealed that SPs were 49% and 83% shorter with TES and PBS, respectively, than with TMS. As TMS is more effective than TES or PBS in activating cortical interneurons, these findings support the idea that a significant component of the SP arises from intracortical mechanisms.  相似文献   
110.
From 1979 to 1987, 907 patients with non-oat cell carcinoma of the lung were subjected to thoracotomy: of these, 685 (75.5%) underwent radical resection of the lung tumour. The 230 stage IIIa patients were studied in this paper. These were divided into three groups. First group: 93 patients with only local parietal or mediastinal spread without involvement of the mediastinal lymph nodes (T3N0-1M0); the 5-year survival of this group was 35% (44.1% when the ribs and muscles were not affected). A second group of 118 patients had tumour spreading to the mediastinal lymph nodes, but without local involvement (T1-2N2M0): this group had a 5-year survival of 22.3%. The 5-year survival was better in patients without metastases in the subcarinal lymph nodes than in patients with them (23.76% versus 12.89%). Skipping of lymphatic levels was frequent: 37% of patients with metastasis to mediastinal lymph nodes did not have metastases in the lymph nodes of the lung; 10% of tumours removed by lobectomy had metastases in the lymph nodes of the residual lobe. The third group with parietal and lymphatic mediastinal invasion (T3N2M0) had a poor survival (13.5% at 5 years). The author concludes that it is possible to achieve an acceptable 5-year survival in selected cases with metastasis to mediastinal lymph nodes: when the CT scan demonstrated mediastinal lymph nodes larger than 1.5 cm, mediastinoscopy was carried out and, if positive, the patient was judged inoperable.  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