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   187272篇
  免费   1862篇
  国内免费   73篇
耳鼻咽喉   1212篇
儿科学   6989篇
妇产科学   3296篇
基础医学   18251篇
口腔科学   1778篇
临床医学   13551篇
内科学   33514篇
皮肤病学   934篇
神经病学   17804篇
特种医学   9212篇
外科学   29969篇
综合类   2408篇
现状与发展   1篇
一般理论   10篇
预防医学   19234篇
眼科学   2918篇
药学   10143篇
中国医学   662篇
肿瘤学   17321篇
  2024年   53篇
  2023年   226篇
  2022年   422篇
  2021年   772篇
  2020年   436篇
  2019年   636篇
  2018年   22443篇
  2017年   17704篇
  2016年   19908篇
  2015年   1348篇
  2014年   1400篇
  2013年   1460篇
  2012年   7979篇
  2011年   22046篇
  2010年   19345篇
  2009年   11971篇
  2008年   20133篇
  2007年   22381篇
  2006年   1183篇
  2005年   2763篇
  2004年   3930篇
  2003年   4831篇
  2002年   2902篇
  2001年   299篇
  2000年   428篇
  1999年   205篇
  1998年   252篇
  1997年   249篇
  1996年   117篇
  1995年   122篇
  1994年   116篇
  1993年   71篇
  1992年   38篇
  1991年   87篇
  1990年   126篇
  1989年   77篇
  1988年   57篇
  1987年   40篇
  1986年   27篇
  1985年   32篇
  1984年   23篇
  1983年   28篇
  1982年   25篇
  1980年   45篇
  1938年   60篇
  1937年   26篇
  1935年   23篇
  1934年   31篇
  1932年   57篇
  1930年   48篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
93.

Background  

It has been observed that ras-transformed cell lines in culture have a higher phosphatidylcholine (PC) biosynthesis rate as well as higher PC-degradation rate (increased PC-turnover) than normal cells. In correspondence to these findings, the concentrations of the PC-degradation product lyso-phosphatidylcholine (LPC) in cancer patients were found to be decreased. Our objective was the systematic investigation of the relationship between LPC and inflammatory and nutritional parameters in cancer patients. Therefore, plasma LPC concentrations were assessed in 59 cancer patients and related to nutritional and inflammatory parameters. To determine LPC in blood plasma we developed and validated a HPTLC method.  相似文献   
94.
95.
The depth and extent of the invasion of the skull base by a tumor are the most critical information for successful en bloc resection of the tumor. The only means available for the evaluation of these factors are CT or MRI images. In order to clarify the ability of these imaging modes to delineate the invasion of the skull base, preoperative images of ten patients who underwent en bloc resection of skull base tumors at Kobe University Hospital were compared with the histopathological findings of the resected specimens. CT proved to be superior to MRI for evaluating bone destruction of the skull base. On the other hand, MRI provided more useful information about intracranial invasion than CT. As a hypertrophic linear shadow on Gd-enhanced MRI represented dural invasion or thickened dura mater adjacent to the tumor, this technique should be taken into consideration to determine the dural resection. We concluded that preoperative evaluation of the depth of skull base invasion by both CT and Gd-enhanced MRI is essential for planning complete tumor resection.  相似文献   
96.
97.
Summary To investigate the distribution of possible novel mutations from parkin gene in variant subset of patients with Parkinson’s disease (PD) in China and explore whether parkin gene plays an important role in the pathogenesis of PD, 70 patients were divided into early-onset group and late-onset group; 70 healthy subjects were included as controls. Genomic DNA from 70 normal controls and from those of PD patients were extracted from peripheral blood leukocytes by using standard procedures. Mutations of parkin gene (exon 1–12) in all the subjects were screened by PCR-single strand conformation polymorphism (SSCP), and further sequencing was performed in the samples with abnormal SSCP results, in order to confirm the mutation and its location. A new missense mutation Gly284Arg in a patient and 3 abnormal bands in SSCP electrophoresis from samples of another 3 patients were found. All the DNA variants were sourced from the samples of the patients with early-onset PD. It was concluded that Parkin point mutation also partially contributes to the development of early-onset Parkinson’s disease in Chinese. WANG Tao, male, born in 1961, Associate Professor This work was supported by grants from the key program of the special scientific project of Scientific & Technologic Agency of Hubei Province (Serial No. 2001AA308B01) and the Hygienic Research Project of Hygienic Agency of Hubei province (Serial No. WJ 01529).  相似文献   
98.
99.
100.
In a population-based longitudinal cohort study, we tested the hypothesis that children growing up in a high-traffic polluted urban area (UA) in the Athens' basin have higher prevalence of allergies and sensitization when compared with those growing up in a Greek provincial rural area (RA). We recruited 478 and 342 children aged 8-10 living in the UA and the RA, respectively. Respiratory health was assessed by a parent-completed questionnaire in three phases: 1995-96 (phase 1), 1999-2000 (phase 2), 2003-04 (phase 3) and skin-prick testing to common indoor and outdoor aeroallergens was performed at phases 1 and 2. Reported asthma and eczema did not differ between the two areas, whereas reported hay fever was persistently more prevalent in the UA than in the RA (16.5%, 17.0%, 18.2% vs. 7.0%, 8.3%, 9.6%, respectively). Sensitization was more prevalent in the UA at both phases (19.0% vs. 12.1% in phase 1, 20.0% vs. 14.1% in phase 2). Residential area contributed independently to sensitization to >or=1 aeroallergens (OR: 0.29; 95% CI: 0.13-0.66; p = 0.003) and to polysensitization (OR: 0.28; 95% CI: 0.10-0.82; p = 0.020) in phase 1. These associations were independent of farming practices. No significant contributions were found in phase 2. Our results suggest that long-term exposure to urban environment is associated with a higher prevalence of hay fever but not of asthma or eczema. The negative association between rural living and the risk of atopy during childhood, which is independent of farming practices, implies that it is mainly driven by an urban living effect.  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