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   192192篇
  免费   13720篇
  国内免费   5144篇
耳鼻咽喉   2554篇
儿科学   3112篇
妇产科学   2517篇
基础医学   26124篇
口腔科学   4407篇
临床医学   20663篇
内科学   30938篇
皮肤病学   5047篇
神经病学   12635篇
特种医学   9602篇
外国民族医学   22篇
外科学   22150篇
综合类   14196篇
现状与发展   19篇
一般理论   29篇
预防医学   13141篇
眼科学   4588篇
药学   19106篇
  80篇
中国医学   6151篇
肿瘤学   13975篇
  2024年   315篇
  2023年   1826篇
  2022年   4984篇
  2021年   7459篇
  2020年   4604篇
  2019年   4850篇
  2018年   5562篇
  2017年   5065篇
  2016年   5714篇
  2015年   8437篇
  2014年   10294篇
  2013年   11633篇
  2012年   17232篇
  2011年   16976篇
  2010年   10895篇
  2009年   9277篇
  2008年   12010篇
  2007年   11341篇
  2006年   10502篇
  2005年   9395篇
  2004年   7572篇
  2003年   6633篇
  2002年   5644篇
  2001年   4155篇
  2000年   3669篇
  1999年   2777篇
  1998年   1255篇
  1997年   1063篇
  1996年   772篇
  1995年   702篇
  1994年   613篇
  1993年   466篇
  1992年   884篇
  1991年   824篇
  1990年   730篇
  1989年   620篇
  1988年   520篇
  1987年   504篇
  1986年   364篇
  1985年   386篇
  1984年   283篇
  1983年   201篇
  1982年   142篇
  1981年   180篇
  1980年   139篇
  1979年   230篇
  1978年   167篇
  1976年   135篇
  1975年   124篇
  1974年   147篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
112.
本文介绍一种用国产热水增压泵替代进口中药包装机加压泵的方法.  相似文献   
113.
目的评价烤瓷贴面的修复效果。方法选择20例患者制作烤瓷贴面92个。复诊时对烤瓷贴面的边缘适合性,边缘着色及颜色进行评价;同时采用牙龈出血指数和菌斑指数评价治疗前后的牙周状况。观察时间为12~18个月。结果5颗牙烤瓷贴面失败,成功率为95.7%;烤瓷贴面治疗前后牙龈出血指数无显著性差异(P>0.05),治疗后菌斑指数降低(P<0.01)。结论烤瓷贴面具有较好的治疗效果。  相似文献   
114.
Considerable indirect evidence implicates participation of natural killer cells (NK) in the pathogenesis of diabetes in BB rats. The most convincing evidence derives from studies showing that anti-CD8 antibody effectively prevents both primary disease onset and autoimmune damage to transplanted islets. However, anti-CD8 treatment depletes both NK and cytotoxic T cells (CTL) since both cell types express the CD8 marker. To study directly the role of NK in diabetic BB rats we used MCA 3.2.3, a monoclonal antibody which selectively depletes normal Lewis rats of NK cells but not CTL. A regimen of ip injected antibody achieved rapid reduction of NK cells in diabetic and nondiabetic BB rats by FACS analysis. NK cell activity remained low in rats treated weekly as evidenced by YAC tumor cell killing. We next studied the effect of NK depletion on disease incidence in diabetes-prone BB rats of which about one half are expected to develop diabetes. Onset and incidence of diabetes in 3.2.3-treated and control antibody-treated aged matched litter mates were equal. These studies suggest that NK cells are not necessary for autoimmune islet destruction in spontaneously diabetic BB rats and support a role for CTL in pathogenesis of the disease.  相似文献   
115.
A 25-year-old female has had brown to erythematous telangiectatic patches and grouped papules on her face, neck, arm, and trunk since childhood following B.C.G. vaccination. Histopathologically, the lesions consisted of hyperkeratosis, slight acanthosis, tuberculoid granulomas with some Langerhans type giant cells in the mid-dermis. Although various forms of cutaneous tuberculosis after B.C.G. vaccination have been reported, it was difficult for us to assign the patient's skin lesion to any specific disease entity. Remission of her cutaneous lesions occurred clinically and histopathologically after treatment with isoniazid and rifampin.  相似文献   
116.
BACKGROUND. Biomaterial pretreatment with endothelial cell mitogens may enhance endothelialization. METHODS. Modified fibrin glue (FG) containing 1 ng/cm2 recombinant 125I-labeled fibroblast growth factor type 1 (125I-FGF-1), 20 micrograms/cm2 heparin, 2.86 mg/cm2 fibrinogen, and 2.86 x 10(-2) units/cm2 thrombin was pressure perfused into expanded polytetrafluoroethylene (ePTFE) grafts. Grafts were interposed into infrarenal aortas of 24 New Zealand white rabbits and explanted after 0, 5, 30, and 60 minutes and 1, 7, 14, and 30 days. Residual radioactivity was determined by gamma-counting. Remaining 125I-FGF-1 is expressed as percent of value at time 0. To determine the effect of the FG/FGF-1 on graft healing, three groups of 50 x 4 mm 60 microns internodal-distance nonreinforced ePTFE grafts were implanted in the aortoiliac position of 12 dogs. Group I (n = 12) contained the complete modified FG, group II (n = 6) contained FG with heparin but no FGF-1, and group III (n = 6) contained untreated identical ePTFE. Tritiated thymidine (0.5 microCi/kg) was injected intramuscularly 10 hours before explantation after 7 and 28 days for light and electron microscopy and en face autoradiography. RESULTS. Retention of 125I-FGF-1 showed rapid initial loss (delta %/delta min = -24.1) followed by slow loss after 1 hour (delta %/delta min = -0.03), with 13.4% +/- 6.9% remaining at 1 week and 3.8% +/- 1.1% at 30 days. Every FG/FGF-1 graft at 28 days showed extensive capillary ingrowth and confluent endothelialized luminal surfaces, not seen in any specimen of the other two groups. Autoradiography revealed a significant increase (p less than 0.05) in 3H-thymidine incorporation in the FG/FGF-1 grafts at 28 days versus all groups as a function of time and graft treatment. CONCLUSIONS. Pressure perfusion of an FGF-1/FG suspension into 60 microns internodal-distance ePTFE grafts promotes endothelialization through capillary ingrowth and increased endothelial cell proliferation.  相似文献   
117.
The expression and localization of a novel protein kinase C delta (nPKC delta) mRNA were investigated using Northern blotting and in situ hybridization in the developmental process of mouse brain. In adult mice, nPKC delta was abundantly expressed in the thalamus, moderately in the pons and the cerebellum, but faintly in the cerebral cortex and the spinal cord. By in situ hybridization, the signals were observed specifically at the sensory and motor relay nuclei of the thalamus, the dorsal cochlear nuclei of the pons, and the molecular layer of the cerebellum. When developmental changes in the expression of nPKC delta gene were analyzed by in situ hybridization, it was not detectable in embryonic and neonatal brains, very weakly expressed in the thalamus in the first week, and highly expressed at two weeks of age. These results suggest that the gene expression of nPKC delta is strictly controlled by both the cell type and the developmental process.  相似文献   
118.
Case report 487     
The opinions or assertions contained herein are the private views of the authors and are not to be construed as official nor as reflecting the views of the United States Air Force  相似文献   
119.
120.
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