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   1074328篇
  免费   93681篇
  国内免费   4746篇
耳鼻咽喉   17682篇
儿科学   34868篇
妇产科学   29319篇
基础医学   132916篇
口腔科学   27246篇
临床医学   102836篇
内科学   234564篇
皮肤病学   26698篇
神经病学   87137篇
特种医学   43615篇
外国民族医学   340篇
外科学   186444篇
综合类   20069篇
现状与发展   76篇
一般理论   273篇
预防医学   73450篇
眼科学   24489篇
药学   67248篇
  1篇
中国医学   2066篇
肿瘤学   61418篇
  2021年   10225篇
  2020年   10163篇
  2019年   9536篇
  2018年   17406篇
  2017年   15074篇
  2016年   16747篇
  2015年   17837篇
  2014年   28463篇
  2013年   35726篇
  2012年   33539篇
  2011年   35093篇
  2010年   27846篇
  2009年   30460篇
  2008年   33594篇
  2007年   33640篇
  2006年   35871篇
  2005年   32591篇
  2004年   30600篇
  2003年   28527篇
  2002年   28048篇
  2001年   45217篇
  2000年   45643篇
  1999年   39499篇
  1998年   13563篇
  1997年   12462篇
  1996年   12279篇
  1995年   11495篇
  1994年   9951篇
  1993年   9082篇
  1992年   29581篇
  1991年   28408篇
  1990年   27484篇
  1989年   26538篇
  1988年   24571篇
  1987年   24044篇
  1986年   23145篇
  1985年   21908篇
  1984年   16371篇
  1983年   14004篇
  1982年   8616篇
  1979年   14918篇
  1978年   10539篇
  1977年   9025篇
  1976年   8397篇
  1975年   9259篇
  1974年   10950篇
  1973年   10437篇
  1972年   9965篇
  1971年   9134篇
  1970年   8833篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
Case report 506   总被引:1,自引:0,他引:1  
  相似文献   
94.
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   
95.
Summary: This is the first report of the largest study of blood pressure measurement in pregnancy in a New Zealand population using standardized definitions and methodology. Over 3,800 women who delivered in an 8-month period in the Wellington region were included in the study. Blood pressure measurement and the presence of oedema and proteinuria were recorded from booking until delivery and in the puerperium. Only 2.7% of women were unable to be contacted after delivery for details on outcomes. The results established normal ranges for blood pressure throughout pregnancy. The data show that Mood pressure greater than 140/90 until 35 weeks' gestation is outside 2 standard deviations at all gestations and justifies using these measurements as the definition of hypertension in pregnancy. The fall in blood pressure in the 2nd trimester was less than 1 mm Ffg per week in both the systolic and diastolic pressures. This fall was smaller than previously recorded in other studies. Gestational hypertension was the commonest blood pressure abnormality occurring in 15.2% of the population. This represented 69% of the pregnant women with a hypertensive disorder. The overall incidence of both gestational hypertension and preeclampsia was 18.5% which is higher than reported in other parts of the world. In this study obesity was significantly associated with hypertensive disorders in pregnancy. An arm circumference of >33 cm, one of the measurements of obesity, was found in 6.8% of the study population. Even after the effect of arm circumference was taken into account, hypertensive disorders were also more common in Pacific Island women. Ankle oedema was significantly associated with the development of both gestational hypertension and preeclampsia but the incidence of oedema was noted in only 11.9% of the subjects.  相似文献   
96.
97.
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   
98.
99.
100.
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   
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