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   3617048篇
  免费   256091篇
  国内免费   9473篇
耳鼻咽喉   48815篇
儿科学   119956篇
妇产科学   99385篇
基础医学   508267篇
口腔科学   102115篇
临床医学   331242篇
内科学   705196篇
皮肤病学   85352篇
神经病学   292704篇
特种医学   137172篇
外国民族医学   941篇
外科学   540154篇
综合类   77794篇
现状与发展   8篇
一般理论   1392篇
预防医学   276955篇
眼科学   83848篇
药学   264023篇
  12篇
中国医学   7988篇
肿瘤学   199293篇
  2019年   28663篇
  2018年   40855篇
  2017年   31136篇
  2016年   35435篇
  2015年   40141篇
  2014年   55558篇
  2013年   83019篇
  2012年   111908篇
  2011年   118454篇
  2010年   70937篇
  2009年   67335篇
  2008年   110299篇
  2007年   117418篇
  2006年   119032篇
  2005年   114179篇
  2004年   109866篇
  2003年   105669篇
  2002年   102069篇
  2001年   175745篇
  2000年   179881篇
  1999年   151284篇
  1998年   42990篇
  1997年   37867篇
  1996年   37993篇
  1995年   36842篇
  1994年   33680篇
  1993年   31561篇
  1992年   117089篇
  1991年   112933篇
  1990年   109310篇
  1989年   105603篇
  1988年   96564篇
  1987年   94586篇
  1986年   88801篇
  1985年   84783篇
  1984年   63205篇
  1983年   53634篇
  1982年   31459篇
  1981年   28040篇
  1979年   55909篇
  1978年   39251篇
  1977年   33402篇
  1976年   31142篇
  1975年   32956篇
  1974年   39314篇
  1973年   37577篇
  1972年   35093篇
  1971年   32572篇
  1970年   30100篇
  1969年   28767篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Reconstitution of the nasal scaffolding with maintainence of soft tissue proportions either following severe facial trauma or as a sequela to aesthetic rhinoplasty misadventures frequently is best achieved using the stability afforded by bone grafts. Split cranial bone grafts offer many advantages and may be the donor site of choice, and may even allow such surgery to be performed on an outpatient basis in some cases. The use of miniplate or screw osteosynthesis, now commonly accepted as a superior technique in craniomaxillofacial procedures, may simplify fixation of these calvarial nasal bone grafts with an apparent decrease in the risk of resorption.  相似文献   
992.
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   
993.
Cyclodialysis and ciliochoroidal detachment were performed in three eyes of three rabbits and in three eyes of another three rabbits, respectively. After aspiration of the aqueous humor, 0.1 ml of 10% sodium fluorescein was injected intracamerally, and the eyeball was enucleated between 30 minutes and one hour after injection and prepared for fluorescence microscopy. Sodium fluorescein concentrations in the supraciliary space were much greater in the group with cyclodialysis or ciliochoroidal detachment than in the normal control group. These results suggest that (1) in the eye with cyclodialysis, the aqueous humor may freely gain access to the supraciliary space through the cleft between the anterior chamber and the supraciliary space and then be removed rapidly and (2) in the eye with ciliochoroidal detachment, the aqueous humor may pass through the uveoscleral outflow pathway.  相似文献   
994.
995.
Two new naphtho-pyrone glycosides, 9-[(beta-D-glucopyranosyl-(1----6)-O-beta-D-glucopyranosyl)oxy]-10- hydroxy-7-methoxy-3-methyl-1H-naphtho[2,3-c]pyran-1 -one (5) and 6-[(alpha-apiofuranosyl-(1----6)-O-beta-D-glucopyranosyl)oxy]- rubrofusarin (6), together with cassiaside (3) and rubrofusarin-6-beta-gentiobioside (4) were isolated from the seeds of Cassia tora L. Their structures were elucidated on the basis of chemical and spectral data. The naphtho-gamma-pyrone glycosides (3, 4, and 6) were found to have significant hepato-protective effects against galactosamine damage, which were higher than that of silybin from Silybum marianum.  相似文献   
996.
Using a 31P-NMR spectroscopy, we monitored the metabolic kinetics of energy organophosphate compound in rat lens during the process of generating galactose cataract. The most remarkable metabolic change in the earlier phase of galactose cataract formation was found in alpha-glycerophosphate. This increased significantly, as compared to controls, since the day 3 of giving feed containing 25% galactose. The high level lasted for up to three weeks, decrease followed by a gradual decrease and subsequently a significant decrease at five weeks. Adenosine triphosphate (ATP) showed a significant decrease in the galactose group compared to the controls from two weeks after beginning of the experiment and the decrease continued. Inorganic orthophosphate increased gradually in the galactose group as compared to the controls, the increase being of significance at one week reading a maximum at two weeks followed by a subsegment decrease. Our basic study suggests that 31P-NMR spectroscopy is a useful technique in lens of the metabolic kinetics, to noninvasively determine the pathophysiology of galactose cataract, which has been studied biochemically and histologically.  相似文献   
997.
998.
999.
Clinical pharmacokinetics-pharmacodynamics of anticancer drugs   总被引:3,自引:0,他引:3  
  相似文献   
1000.
Knowledge of the health status of, and patterns of health care service utilization by rural Australian communities, is scant. This deficiency limits attempts to formulate policies designed to bring about efficient, effective and equitable delivery of health care services. This article reports the results of a health interview survey conducted in the Wimmera region of Victoria during spring 1984. The results demonstrate not only that patterns of morbidity in rural areas differ from the Australian average, but also that the health status of rural dwellers is worse than that of most Australians. Evidence suggests that while accessibility is not the most significant determinant of utilization of health care services, distance from services does affect propensity to use them.  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