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   987481篇
  免费   68367篇
  国内免费   2807篇
耳鼻咽喉   13575篇
儿科学   30778篇
妇产科学   27433篇
基础医学   137842篇
口腔科学   26778篇
临床医学   83534篇
内科学   202361篇
皮肤病学   20394篇
神经病学   79746篇
特种医学   40030篇
外国民族医学   337篇
外科学   156699篇
综合类   19757篇
一般理论   436篇
预防医学   70626篇
眼科学   21714篇
药学   69157篇
中国医学   1919篇
肿瘤学   55539篇
  2021年   8850篇
  2019年   8957篇
  2018年   12091篇
  2017年   9296篇
  2016年   9989篇
  2015年   11293篇
  2014年   15957篇
  2013年   23818篇
  2012年   32543篇
  2011年   34244篇
  2010年   20457篇
  2009年   19157篇
  2008年   31916篇
  2007年   33356篇
  2006年   33324篇
  2005年   32774篇
  2004年   31109篇
  2003年   29857篇
  2002年   28956篇
  2001年   41901篇
  2000年   42971篇
  1999年   36887篇
  1998年   10774篇
  1997年   9785篇
  1996年   9602篇
  1995年   8969篇
  1994年   8489篇
  1993年   7997篇
  1992年   28508篇
  1991年   27272篇
  1990年   26679篇
  1989年   25597篇
  1988年   23811篇
  1987年   23392篇
  1986年   22508篇
  1985年   21406篇
  1984年   16134篇
  1983年   13752篇
  1982年   8393篇
  1979年   14730篇
  1978年   10384篇
  1977年   8789篇
  1976年   8264篇
  1975年   9081篇
  1974年   10818篇
  1973年   10290篇
  1972年   9753篇
  1971年   9000篇
  1970年   8645篇
  1969年   8077篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Electrocardiographic symptoms were evaluated in 53 patients with an additional left-ventricular chorda (ALVC), detected by two-dimensional echocardiography. Signs of early ventricular repolarization (EVR) were identified in 45 (84.9%) patients. A transverse ALVC was more common in EVR-free patients (87.5%), as compared to patients with ALVC + EVR combinations (51.1%; p less than 0.05).  相似文献   
82.
83.
84.
Noninvasive localized proton magnetic resonance spectroscopy (MRS) was used for differential diagnosis of a focal brain lesion in a 2.5-year-old girl. The clinical signs were a mild head tilt and neck pain. Magnetic resonance imaging (MRI) revealed a lesion in the right hemisphere of the cerebellum, but its nature remained obscure. In this lesion quantitative determinations of cerebral metabolites by fully relaxed, short-echo-time proton MRS revealed markedly lowered N-acetylaspartate (NAA) and pronounced elevations of choline-containing compounds (Cho) and myo-inositol (Ins), whereas metabolite concentrations in cortical gray matter and white matter were within normal ranges. The metabolite pattern of the lesion indicated loss of vital neuroaxonal tissue (low NAA) and enhanced glial proliferation (high Cho and Ins), which, together with the MRI morphology, suggested a brain tumor. The diagnosis was established by neurosurgical exploration and total extirpation of the tumor. Histology confirmed an astrocytoma (WHO II). After 2 weeks' recovery the child was discharged with no neurological signs.  相似文献   
85.
86.
87.
Background : Methimazole, an anti-thyroid drug, was recently found to be useful in the treatment of systemic lupus erythematosus and other autoimmune diseases. Moreover, decreased thyroid hormone production is associated with a variety of immunological manifestations, such as reduced activation of CD4+ cells, increased CD8+ cell activity and reduced soluble IL-2 receptors. In the present study we examined the effects of methimazole and propylthiouracil on a rat model of experimental colitis.
Methods : Colitis was induced by intracolonic administration of 30 mg trinitrobenzene sulphonic acid (TNB). Two weeks prior to induction of colitis, rats were treated by either methimaziole (0.04%) or propylthiouracil (0.01%) in drinking water after a week of free access to water. Rats were sacrificed 48 h or 7 days after induction of colitis. The colon was isolated, rinsed with ice-cold water and weighed. Damage was assessed both macroscopically and microscopically and myeloperoxidase (MPO) activity determined.
Results : All treated rats were hypothyroid as manifested by a significant elevation of thyroid stimulating hormone (TSH), by comparison with the control groups (mean -1.82±0.40 versus 0.11±0.02 mmol/L, respectively). The inflammatory response elicited by TNB resulted in severe mucosal damage 48 h after damage induction, which persisted for 7 days. Pre-treatment with either methimazole 0.04% or propylthiouracil 0.01% significantly decreased mucosal damage macroscopically (lesion area, lesion score and segmental weight) microscopically and also significantly decreased MPO level at both time points ( P <0.01).
Conclusions : Methimazole and propylthiouracil significantly reduce mucosal damage and colonic weight in a rat model of colitis. The mode by which they do so remains to be studied.  相似文献   
88.
89.
90.
The results of the in vitro fertilisation programme at Tygerberg Hospital for the period April 1983 to January 1988 are presented. Of the 1117 laparoscopies performed, 825 patients reached the transfer stage. A live-birth rate of 9.3% was achieved. The pregnancy rate after transfer of 4 embryos was 25.9% compared with 15.4% after 2 embryos and 10.8% after 3 embryos (P = less than 0.0001). The multiple pregnancy rate was 2.8% in the group receiving 2 embryos and 11.7% and 10.4% in those receiving 3 and 4 embryos, respectively. Of the 77 successful pregnancies (90 babies), 1 baby died at 34 weeks' gestation as the result of abruptio placentae due to preeclampsia and 1 cot death occurred. The only congenital abnormality encountered was a cleft palate.  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