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   146868篇
  免费   7958篇
  国内免费   171篇
耳鼻咽喉   2251篇
儿科学   6477篇
妇产科学   4952篇
基础医学   20339篇
口腔科学   4557篇
临床医学   11303篇
内科学   27375篇
皮肤病学   3767篇
神经病学   11916篇
特种医学   6069篇
外国民族医学   32篇
外科学   23267篇
综合类   1741篇
一般理论   31篇
预防医学   8290篇
眼科学   3899篇
药学   10160篇
中国医学   358篇
肿瘤学   8213篇
  2019年   1101篇
  2018年   1515篇
  2017年   1307篇
  2016年   1643篇
  2015年   1786篇
  2014年   2278篇
  2013年   3534篇
  2012年   4443篇
  2011年   4502篇
  2010年   2817篇
  2009年   2808篇
  2008年   4424篇
  2007年   4810篇
  2006年   4946篇
  2005年   5090篇
  2004年   4839篇
  2003年   4687篇
  2002年   4566篇
  2001年   7965篇
  2000年   7873篇
  1999年   6754篇
  1998年   1985篇
  1997年   1878篇
  1996年   1611篇
  1995年   1496篇
  1994年   1364篇
  1993年   1332篇
  1992年   4475篇
  1991年   4238篇
  1990年   4259篇
  1989年   4029篇
  1988年   3633篇
  1987年   3518篇
  1986年   3353篇
  1985年   3132篇
  1984年   2421篇
  1983年   1956篇
  1982年   1153篇
  1981年   1121篇
  1980年   944篇
  1979年   2162篇
  1978年   1596篇
  1977年   1316篇
  1976年   1133篇
  1975年   1406篇
  1974年   1461篇
  1973年   1418篇
  1972年   1240篇
  1971年   1170篇
  1970年   1060篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
22.
23.
Based on a standardized in-vitro method for quantifying the activity of prostaglandin-synthetase by means of coupling malondialdehyde with 2-thiobarbituric acid the possibility of using this method also as ex-vivo technique is described. By this, more favourable prerequisites to pharmacological valuation of the effects of potential antiinflammatory substances exists compared to the application of in-vitro results, only.  相似文献   
24.
A consecutive series of patients (1978–1981) comprising all patients with acute leukaemia from a population of 475000 inhabitants was reviewed. Thus, 94 patients were diagnosed as having acute leukaemia. No patients were lost from follow-up. The incidence figures of ALL and AML differed significantly from those of Sweden as a whole. 9 patients were < 15 years old. The median age of adult patients was 64 years, 60.8% being ≥ 60 years old. Of adult patients with AML, 20% had a preleukaemic history (chronic myeloproliferative disorders, myelodysplastic syndromes and others). None of 6 patients with leukaemia as a metamorphosis of a chronic myeloproliferative disorder achieved a complete remission. The overall remission rate of the remaining adult patients was 25%. Treated patients, 15–39 years old, with AML without any preleukaemic history, had a complete remission rate of 80% compared to 12% for patients ≥ 60 years old with the same diagnosis. Of 60 patients with ‘primary’ AML, 14 were not treated, mainly because of advanced age and complicating diseases. Most of these patients died within a week of admission.  相似文献   
25.
This study compares the weight of the human brain to gestational age and body dimensions. A new formula for calculating the rate of growth is proposed. It consists of a second order polynomial function: Y = A0 + A1X + A2X2, in which Y is brain weight, body weight, height, or body surface area; X is gestational age in weeks and A0, A1, and A2 are statistically estimated coefficients. In utero, the growth rate is most rapid for body weight, followed in decreasing order by brain weight, body surface area, and height. Brain growth is the same for both sexes in black and white races; it accelerates between the 20th and 45th weeks of gestation. The size of the newborn infant brain is directly related to gestational age and body size and is not determined by sex or race.  相似文献   
26.
27.
In 50 children, 4 months to 12 years of age, with minor head trauma non-target visual event-related potentials were performed and compared to a second registration of the potentials some months later. On following-up there was a clear tendency for a relative improvement of the latencies of the endogenous potentials. In this way non-target visual event-related potentials proved to be of value in the investigation of mental impairment in early childhood.  相似文献   
28.
The sequence of structural changes involved in postnatal photoreceptor differentiation, maturation and early degeneration was studied in young Abyssinian cats and kittens with hereditary rod-cone degeneration and compared to maturation in normal controls. In affected cats the earliest change seen was disorientation of outer segment discs in the majority of the rods, while other rods appeared to develop and mature normally. Such disorientation of discs (at oblique angles or parallel to the longitudinal axis of the outer segment, or whorls of discs) is considered as 'immaturity', since controls also showed a substantial number of disoriented rod outer segment discs at this young age. At postnatal day 35 the difference between affected animals and controls was marked with a high frequency of immature appearing rod outer segment discs in affected animals, while all rod outer segment discs were adult-like and arranged in an orderly manner in controls. Cones seemed unaffected at this age. More severe changes in affected rod outer segments in the form of disintegration of discs (vacuolization and clumping of disc material, or formation of debris), which we consider to represent degeneration, were first observed at the time when retinal maturation normally occurs in the cat, i.e. 150 days postnatally. Subsequently a drop-out of rods was seen, primarily of rods with disoriented and disintegrated outer segment discs, followed by a slow, progressive degeneration of rods that had developed and matured normally. Cones appeared normal during the time of retinal development and maturation and it was not until the age of 2-3 years (Narfstr?m and Nilsson, 1986, Incest. Ophthalmol, Vis. Sci. 27, 1569-76) that degenerative changes were seen also in cones.  相似文献   
29.
30.
The duodenal contents were examined in 81 patients with gastroduodenal ulcer. Bile acid concentrations, alkaline phosphatase activity, and sodium ion concentration were measured for the detection of duodenogastric reflux. Measurements of sodium ion concentration permitted estimation of the immediate volume of the duodenogastric reflux in the gastric contents. No methods for duodenogastric reflux detection should be given preference in examinations of peptic ulcer patients. Multiple-modality studies appear to be the most effective.  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