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   1301876篇
  免费   99506篇
  国内免费   2065篇
耳鼻咽喉   18590篇
儿科学   45097篇
妇产科学   35581篇
基础医学   185700篇
口腔科学   34009篇
临床医学   114534篇
内科学   262420篇
皮肤病学   28428篇
神经病学   102851篇
特种医学   51750篇
外国民族医学   660篇
外科学   198264篇
综合类   27210篇
现状与发展   1篇
一般理论   403篇
预防医学   98480篇
眼科学   28331篇
药学   96419篇
  3篇
中国医学   2472篇
肿瘤学   72244篇
  2019年   9666篇
  2018年   13822篇
  2017年   10452篇
  2016年   11448篇
  2015年   13075篇
  2014年   17992篇
  2013年   27482篇
  2012年   37829篇
  2011年   40004篇
  2010年   23834篇
  2009年   22789篇
  2008年   38213篇
  2007年   40887篇
  2006年   41120篇
  2005年   39943篇
  2004年   39014篇
  2003年   37760篇
  2002年   36951篇
  2001年   64131篇
  2000年   66610篇
  1999年   56558篇
  1998年   15335篇
  1997年   13908篇
  1996年   14346篇
  1995年   13559篇
  1994年   12883篇
  1993年   11885篇
  1992年   44620篇
  1991年   43543篇
  1990年   42286篇
  1989年   40186篇
  1988年   36937篇
  1987年   36281篇
  1986年   33661篇
  1985年   32326篇
  1984年   24197篇
  1983年   20330篇
  1982年   11789篇
  1981年   10735篇
  1979年   21374篇
  1978年   14843篇
  1977年   12553篇
  1976年   11715篇
  1975年   12643篇
  1974年   14682篇
  1973年   14131篇
  1972年   12957篇
  1971年   11740篇
  1970年   11054篇
  1969年   10024篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
Medullary thyroid carcinoma (MTC) is a rare form of thyroid cancer representing about 10% of all thyroid malignancies. It occurs mostly as a sporadic tumor or in association with autosomal dominant inherited cancer syndromes--multiple endocrine neoplasia (MEN) types 2A and 2B and familial MTC. Germline mutations in exons 8, 10, 11, 13, 14, 15 and 16 of the RET proto-oncogene are found in most of the familial cases. There are only a few published data reporting multiple germline mutations in the RET proto-oncogene. We have detected double germline mutations in 2 different exons on the same RET allele in two MEN 2 families. In the MEN 2A family, double germline mutation in exons 10 (Cys620Phe) and 13 (Tyr791Phe) was detected. In the MEN 2B family, beside the classical germline mutation in exon 16 (Met918Thr) a second germline mutation in exon 13 (Tyr791Phe) was found. This study revealed that MEN 2 syndromes can also be caused by double germline mutations in the RET proto-oncogene and these families can be added to small worldwide cohort of families with multiple germline mutations.  相似文献   
23.
24.
25.
26.
Infections due to Penicillium species other than P.marneffei are rare. We identified a boy with X-linked chronic granulomatous disease (X-CGD) with a pulmonary nodule and adjacent rib osteomyelitis caused by Penicillium piceum. The only sign of infection was an elevated sedimentation rate. P. piceum was isolated by fine needle aspirate and from excised infected tissues. Surgical removal and one year of voriconazole treatment were very well tolerated and led to complete recovery. Microbiological, microscopic and molecular studies support the fungal diagnosis. P. piceum should be considered as a relevant pathogen in immunocompromised patients.  相似文献   
27.
Abstract: Background: Fetal pulse oximetry improves the assessment of fetal well‐being during labor. The objective of this study was to evaluate women's satisfaction with their experience with this additional technology. Methods: We surveyed women participating in the FOREMOST trial, a randomized controlled trial comparing the addition of fetal pulse oximetry (FPO) to conventional cardiotocograph (CTG) monitoring (intervention group), versus CTG‐only (control group), in the presence of nonreassuring fetal status during labor. Our survey evaluated 3 aspects of women's experience: labor, fetal monitoring, and participation in the research. The survey was administered within a few days of giving birth and repeated 3 months later. Results: No differences were found between the intervention and control groups for women's evaluations of their labor, fetal monitoring, research, or overall experiences when surveyed on both occasions. Within each study group, a small but statistically significant decline occurred in women's scores for their experience of labor and overall experience from the initial survey close to the time of giving birth, to 3 months later. The magnitude of differences in responses over time was similar for the both groups. Women were more satisfied after a spontaneous or assisted vaginal birth than after cesarean section. Length of time the research midwife was present had a significant positive effect on women's ratings of their experience several days after giving birth (p = 0.006), but no effect at 3 months. Conclusions: The addition of fetal pulse oximetry for the assessment of fetal well‐being during labor did not affect childbearing women's perceptions of fetal monitoring or their labor. Women evaluated their experience in the research process positively overall. Small changes occurred in women's perception of their satisfaction over time. (BIRTH 33:2 June 2006)  相似文献   
28.
29.
30.
OBJECTIVE: To establish reference intervals for the fetal right, left and total lung volumes and heart volume between 12 and 32 weeks of gestation. METHODS: Fetal lung and heart volumes were measured using three-dimensional (3D) ultrasound in 650 normal singleton pregnancies at 12-32 weeks. The VOCAL (Virtual Organ Computer-aided AnaLysis) technique was used to obtain a sequence of six sections of each lung and the heart around a fixed axis, each after a 30 degrees rotation from the previous one. The rotation axis for the lungs extended from the apex to the upper limit of the diaphragm dome, and the rotation axis for the heart extended from its apex to its connection to the great vessels. The contour of each of these organs was drawn manually in the six different rotation planes to obtain the 3D volume measurement. In 60 cases the fetal lungs and heart volumes were measured by the same sonographer twice and also by a second sonographer once in order to compare the measurements and calculate intra- and interobserver agreement. RESULTS: The total lung volume and heart volume increased with gestation, from respective mean values of 1.6 and 0.6 mL at 12 weeks to 10.9 and 4.3 mL at 20 weeks and 49.3 and 26.6 mL at 32 weeks. The right to left lung volume ratio did not change significantly with gestation (median, 0.7), whereas the heart to total lung volume ratio increased with gestation from about 0.3 at 12 weeks to 0.5 at 32 weeks. In the Bland-Altman plot, the difference between paired measurements by two sonographers was, in 95% of the cases, less than 0.05, 0.5 and 1.9 mL for each lung at 12-13, 19-22 and 29-32 weeks, respectively, and the corresponding values for the heart volumes were 0.04, 0.4 and 2.3 mL. CONCLUSIONS: In normal fetuses the lung and heart volumes increase between 12 and 32 weeks of gestation. The extent to which in pathological pregnancies possible deviations in these measurements from normal prove to be useful in the prediction of outcome remains to be determined.  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