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   2473211篇
  免费   183992篇
  国内免费   5536篇
耳鼻咽喉   35047篇
儿科学   78669篇
妇产科学   71580篇
基础医学   347640篇
口腔科学   71029篇
临床医学   216043篇
内科学   487214篇
皮肤病学   57224篇
神经病学   201044篇
特种医学   96135篇
外国民族医学   879篇
外科学   376262篇
综合类   57673篇
现状与发展   8篇
一般理论   863篇
预防医学   184372篇
眼科学   57758篇
药学   180172篇
  5篇
中国医学   5443篇
肿瘤学   137679篇
  2018年   25299篇
  2017年   19640篇
  2016年   21993篇
  2015年   24739篇
  2014年   35043篇
  2013年   52757篇
  2012年   70444篇
  2011年   74569篇
  2010年   44132篇
  2009年   42513篇
  2008年   70145篇
  2007年   75167篇
  2006年   76155篇
  2005年   73892篇
  2004年   71046篇
  2003年   68258篇
  2002年   66708篇
  2001年   119197篇
  2000年   122284篇
  1999年   102653篇
  1998年   28458篇
  1997年   25835篇
  1996年   25376篇
  1995年   24068篇
  1994年   22178篇
  1993年   20703篇
  1992年   78668篇
  1991年   75598篇
  1990年   73424篇
  1989年   70866篇
  1988年   65627篇
  1987年   64238篇
  1986年   61104篇
  1985年   57978篇
  1984年   43957篇
  1983年   37194篇
  1982年   22557篇
  1981年   20337篇
  1979年   40530篇
  1978年   28790篇
  1977年   24577篇
  1976年   22554篇
  1975年   24656篇
  1974年   29292篇
  1973年   28518篇
  1972年   27047篇
  1971年   24910篇
  1970年   23756篇
  1969年   22529篇
  1968年   21260篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
Forty-six (85%) basal cell and eight (15%) squamous cell carcinomas of the eyelids were treated with electron beams between 1963 and 1983. Lesion sizes ranged from microscopic to 4 cm, with 28 lesions larger than 1 cm. Thirty-eight lesions were treated with radiotherapy after incisional biopsy, and 16 were treated after excisional biopsy (specimens showed positive margins). Doses varied from 45 to 72 Gy, with daily fractions ranging from 2.12 to 4.0 Gy. There were six disease recurrences (10.9%): three in the treatment field and three at the treatment margin. Four of six recurrences were subsequently controlled by limited surgical excision and repair with preservation of the eye, whereas the other two required enucleation. Treatment sequelae such as skin atrophy, telangiectasis, and cosmetic results were evaluated in terms of radiotherapy parameters, pretreatment surgery, and size of the lesion. In 44 patients, the overall cosmetic result was judged as good to excellent, five patients had a mild to modest degree of deformity, and five had significant deformity. Such deformity was usually associated with tumor destruction or previous surgery. No major complications were noted.  相似文献   
952.
953.
Weaver mutant mice are characterized by a decrease in striatal dopamine (DA), which is associated with a progressive loss of DA neurones in the substantia nigra. This mutant thus provides the opportunity to examine the functional effects of DA neurones grafted to the striatum in a genetic model of parkinsonism. Ventral mesencephalic tissue from normal foetuses was placed on the surface of the right dorsal striatum of adult weaver mutants. After grafting, animals were tested for methamphetamine-induced circling behaviour. Mutants with DA containing grafts displayed a significant circling bias toward the left, non-grafted side. Mutants without grafts did not display any rotational bias to either side. These results demonstrate that grafted DA containing neurones establish a functional innervation of the weaver striatum and suggest that grafting of neural tissue is a viable approach in restoring function in genetic degenerative disorders of the nigrostriatal system.  相似文献   
954.
955.
Serum protein electrophoresis (SPEP) data obtained at diagnosis were available for 98 of 342 patients with chronic lymphocytic leukemia (CLL) identified in a population-based case-control epidemiologic study. Patients tested with SPEP at diagnosis were significantly younger, more likely to have lymphadenopathy, and more likely to have had their conditions diagnosed at a university hospital than those not tested. Four categories of electrophoretic patterns were identified: normal (N = 56), hypogammaglobulinemia (N = 28), hypergammaglobulinemia (N = 11), and monoclonal gammopathy (N = 3). A higher proportion of those with hypergammaglobulinemia were black, and patients with hypergammaglobulinemia and monoclonal gammopathy were more likely to die within the first year following diagnosis than patients in the other SPEP groups. No association was found, however, between SPEP pattern and a clinical staging classification for CLL. These findings suggest that SPEP may be a useful adjunct in categorizing possible subtypes of CLL and developing future clinical staging classifications.  相似文献   
956.
The electrocardiographic features of Noonan's syndrome have been known for several years, but the discordance between these electrical findings and the underlying haemodynamic disorders remains unexplained. In an attempt to elucidate the genesis of electrical abnormalities, we present here a retrospective study of 14 children with Noonan's disease, aged from a few days to 16 years and evaluated by electrocardiography, vectography, one- or two-dimensional echocardiography, angiography and His bundle electrophysiology. The electrocardiographic abnormalities observed concerned ventricular depolarization and intracardiac electric conduction with, notably, a QRS axis directed towards the right upper part of the electric field and a first degree infra-hisian atrioventricular block (His bundle potentials). Vectography showed in some cases an image of inferior pseudo-necrosis due to the absence of initial inferior forces; this image is highly characteristic. In other cases the QRS loop showed an image of left segmental block which is unusual in this type or cardiac pathology (pulmonary stenosis with or without atrial septal defect of the ostium secundum type).  相似文献   
957.
Mentally retarded adolescents and MA-matched nonretarded children participated in three experiments designed to examine differences in language-processing efficiency. A compressed speech technique was used in Experiments 1 and 2. Experiment 3 relied on a sentence-picture verification procedure. Our results suggest that retarded and nonretarded individuals differ in the speed with which they are able to execute the semantic-analytic processes but not necessarily the phonological encoding processes that are involved in auditory language comprehension. In addition, the data suggest a possible group difference in the quality of the semantic representation encoded during sentence processing.  相似文献   
958.
959.
960.
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