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   907747篇
  免费   57672篇
  国内免费   2319篇
耳鼻咽喉   12533篇
儿科学   28694篇
妇产科学   26159篇
基础医学   126901篇
口腔科学   24721篇
临床医学   75030篇
内科学   183966篇
皮肤病学   19033篇
神经病学   71736篇
特种医学   36572篇
外国民族医学   336篇
外科学   142794篇
综合类   19036篇
一般理论   247篇
预防医学   64706篇
眼科学   20123篇
药学   63965篇
  14篇
中国医学   1807篇
肿瘤学   49365篇
  2018年   9107篇
  2017年   7234篇
  2016年   7764篇
  2015年   8763篇
  2014年   12420篇
  2013年   19269篇
  2012年   25732篇
  2011年   27365篇
  2010年   16635篇
  2009年   15827篇
  2008年   26213篇
  2007年   27856篇
  2006年   28015篇
  2005年   27558篇
  2004年   26402篇
  2003年   25561篇
  2002年   25153篇
  2001年   41442篇
  2000年   42627篇
  1999年   36350篇
  1998年   9989篇
  1997年   9163篇
  1996年   9099篇
  1995年   8462篇
  1994年   8089篇
  1993年   7593篇
  1992年   28244篇
  1991年   27015篇
  1990年   26451篇
  1989年   25393篇
  1988年   23618篇
  1987年   23215篇
  1986年   22283篇
  1985年   21187篇
  1984年   15829篇
  1983年   13492篇
  1982年   8095篇
  1979年   14607篇
  1978年   10218篇
  1977年   8638篇
  1976年   8160篇
  1975年   8968篇
  1974年   10712篇
  1973年   10193篇
  1972年   9668篇
  1971年   8921篇
  1970年   8592篇
  1969年   8031篇
  1968年   7688篇
  1967年   7088篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
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   
74.
75.
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   
76.
77.
78.
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   
79.
80.
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