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   1548864篇
  免费   115117篇
  国内免费   4766篇
耳鼻咽喉   19461篇
儿科学   50036篇
妇产科学   40986篇
基础医学   228214篇
口腔科学   44875篇
临床医学   146562篇
内科学   302736篇
皮肤病学   30984篇
神经病学   131195篇
特种医学   55763篇
外国民族医学   396篇
外科学   210676篇
综合类   30309篇
现状与发展   2篇
一般理论   602篇
预防医学   138847篇
眼科学   32965篇
药学   111859篇
  6篇
中国医学   3899篇
肿瘤学   88374篇
  2021年   15106篇
  2019年   15643篇
  2018年   21676篇
  2017年   16463篇
  2016年   17388篇
  2015年   19945篇
  2014年   27498篇
  2013年   40591篇
  2012年   57445篇
  2011年   60710篇
  2010年   34246篇
  2009年   31742篇
  2008年   53927篇
  2007年   56921篇
  2006年   56256篇
  2005年   54706篇
  2004年   51817篇
  2003年   48962篇
  2002年   45734篇
  2001年   66988篇
  2000年   68472篇
  1999年   57760篇
  1998年   16857篇
  1997年   15103篇
  1996年   14963篇
  1995年   14042篇
  1994年   13123篇
  1993年   12319篇
  1992年   45152篇
  1991年   44097篇
  1990年   42626篇
  1989年   40414篇
  1988年   37367篇
  1987年   36306篇
  1986年   34574篇
  1985年   32966篇
  1984年   24717篇
  1983年   21017篇
  1982年   12532篇
  1981年   11005篇
  1979年   22143篇
  1978年   15659篇
  1977年   12730篇
  1976年   12430篇
  1975年   12820篇
  1974年   15520篇
  1973年   15201篇
  1972年   13991篇
  1971年   13027篇
  1970年   12063篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A new technique for ultrasonic examination of the hip joint was evaluated in neonatals and infants. An anterior approach was used with the sound sector centered over the femoral head and parallel to the femoral neck. The ultrasonograms corresponded to lateral radiographs of the joint with the leg in Lorenz' first position. It was possible to evaluate the size and depth of the acetabulum and the size and position of the femoral head. The projection also permitted a dynamic examination for determination of hip instability. Thus, the technique provided a method for an objective diagnosis in congenital dislocation of the hip (CDH). In 216 hips, the results of clinical evaluation for CDH were correlated with the degree of instability demonstrated by ultrasound. The comparison showed the clinical diagnosis to be highly inaccurate.  相似文献   
992.
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   
993.
994.
D-xylose disposition was examined in 24 healthy men between 32 and 85 years of age. Xylose was administered as a 5 gm iv infusion and as a 25 gm po solution. Serum xylose concentrations and urinary excretion of intact xylose were determined. There were statistically significant inverse relationships with age for each of the following parameters after intravenous infusion: elimination rate constant (r2 = 0.71); systemic clearance (r2 = 0.66); renal clearance (r2 = 0.66); and nonrenal clearance (r2 = 0.35). Similar inverse relationships were found after oral dosing for the elimination rate constant (r2 = 0.69) and renal clearance (r2 = 0.54). There was no significant age relationship for the apparent volume of distribution or the steady-state volume of distribution. The percentage of the oral and intravenous dose recovered in urine up to 5 hours after dosing was significantly and inversely correlated with age. The implications of the latter finding are discussed with regard to the interpretation of the xylose tolerance test used to assess gastrointestinal absorptive capacity.  相似文献   
995.
Sex and racial predilection, social history, and histology were analyzed in a biopsy-proven adenocarcinoma of the lower esophagus/esophagogastric junction collected over a 5-year period in two teaching institutions with different patient populations. Adenocarcinoma occurred in 11% of patients with biopsy-proven esophageal cancer. The disease occurred only in males at one center, and in a 7:1 ratio of males to females at the other center. Clear racial predilection was seen, since 12 of 13 patients with adenocarcinoma of the esophagus were white, whereas less than 20% of patients with squamous carcinoma of the esophagus were white. The finding of Barrett's epithelium in eight of the 13 cases strongly supports the theory that in white males, Barrett's epithelium is a precursor lesion of adenocarcinoma of the esophagus/esophagogastric junction.  相似文献   
996.
997.
A transfer procedure is very useful in the treatment of strabismus. The most common use of this procedure is to augment an already planned resection or recession procedure so that it can be performed monocularly to reduce an accompanying hypertropia or hypotropia or to collapse the A or V pattern when horizontal surgery is being performed for estropia or exotropia. In transfer procedures, the resultant change of deviation and cosmetic improvement is good or excellent in almost all cases. Some special transfer procedures, such as the Harada-Ito or the Jensen operation, can have dramatic effects on both comfort and change of symptoms for the patient.  相似文献   
998.
999.
Art and soul     
L Dopson 《Nursing times》1987,83(46):16-17
  相似文献   
1000.
The structural behaviour of cobalt(II)phthalocyanine-tetrasodium sulfonate (CoPc(NaSO3)4) ( 1 ), a catalyst used in thiol oxidation, was investigated in the presence of ionenes (poly-quaternary ammonium salts), ( 2 ) using visible light spectroscopy. It was observed that ionenes, which have been shown to promote the catalytic activity, strongly enhance the aggregation of the cobalt complex. No cobalt site isolation occurred up to N+/Co = 105. Furthermore, a stoichiometric CoPc(NaSO3)4/ionene complex appeared to be formed with an N+/Co-ratio of 4:1. This ratio was found to hold for ionenes with M?n varying from 6 100 to 22 000 and charge densities from 0,8 to 1,5. As the charge density was increased, the observed CoPc(NaSO3)4 spectrum was more affected. Experiments with oxygen in alkaline solution revealed that the complex was resistant toward oxygen adduct formation in the presence of ionenes. This phenomenon is discussed in relation to the catalytic activity of the system.  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