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   3228720篇
  免费   248673篇
  国内免费   5633篇
耳鼻咽喉   47255篇
儿科学   102544篇
妇产科学   89457篇
基础医学   459605篇
口腔科学   92957篇
临床医学   289822篇
内科学   626639篇
皮肤病学   66694篇
神经病学   265521篇
特种医学   128205篇
外国民族医学   1170篇
外科学   490063篇
综合类   74177篇
现状与发展   2篇
一般理论   1197篇
预防医学   255275篇
眼科学   75944篇
药学   243028篇
  5篇
中国医学   6006篇
肿瘤学   167460篇
  2018年   32047篇
  2016年   27263篇
  2015年   30968篇
  2014年   44148篇
  2013年   67547篇
  2012年   91473篇
  2011年   96936篇
  2010年   57048篇
  2009年   54401篇
  2008年   92386篇
  2007年   99112篇
  2006年   100263篇
  2005年   97864篇
  2004年   94378篇
  2003年   91047篇
  2002年   90080篇
  2001年   146293篇
  2000年   151161篇
  1999年   128093篇
  1998年   37315篇
  1997年   33606篇
  1996年   33536篇
  1995年   32306篇
  1994年   30381篇
  1993年   28257篇
  1992年   103614篇
  1991年   100809篇
  1990年   98109篇
  1989年   94821篇
  1988年   88111篇
  1987年   86682篇
  1986年   82353篇
  1985年   78860篇
  1984年   59619篇
  1983年   51063篇
  1982年   30966篇
  1981年   27545篇
  1980年   25811篇
  1979年   56272篇
  1978年   39779篇
  1977年   33695篇
  1976年   31855篇
  1975年   34056篇
  1974年   41427篇
  1973年   39481篇
  1972年   37315篇
  1971年   34559篇
  1970年   32449篇
  1969年   30452篇
  1968年   28193篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
To determine whether well-appearing children found incidentally to be neutropenic are at risk for an infectious complication, 44 consecutive months of hematology laboratory records were reviewed. One hundred nineteen patients had medical record documentation regarding clinical course, serial white blood cell counts, and the absence of serious infections, chronic illnesses, or a family history known to be associated with neutropenia. The median duration of documented neutropenia was 13 days (range, 1 to 491 days). Infectious complications occurred in 4 of the 36 patients who had neutropenia for more than 30 days (2 with stomatitis, 1 with cellulitis, and 1 with pneumonia) but in none with shorter durations of neutropenia. There were no significant associations between the development of an infectious complication and either the initial absolute neutrophil count or the lowest documented absolute neutrophil count, nor was there a correlation between the initial absolute neutrophil count and the duration of neutropenia. These data indicate that infectious complications occur in otherwise well children with unexplained neutropenia that persists, but these infections are infrequent and usually are superficial.  相似文献   
992.
Usher syndrome: clinical findings and gene localization studies   总被引:3,自引:0,他引:3  
The issue of genetic heterogeneity is a critical problem in the localization of the gene(s) for Usher syndrome. Based on the data obtained on families studied to date, the differences between type I and type II Usher syndrome appear quite distinct with regard to auditory and vestibular function. Although the majority of families can be confidently diagnosed as typical type I or type II, clinical investigations revealed four families with findings that did not fit into either of the two more common subtypes. These findings emphasize the critical importance of an in-depth clinical analysis concomitant with the linkage investigation to assure accurate subtyping of Usher syndrome. Based on an analysis of only those families with definite type I or type II Usher syndrome, approximately 17% of the genome can be excluded as a potential site of the gene for type I, and 14% can be excluded as the site for the type II gene. This study will continue until the Usher gene(s) is successfully localized.  相似文献   
993.
This paper reports the results of an experimental study modeled after a study conducted by Kaplan et al. The hypothesis tested was: Adolescents who receive a social learning intervention (SLI) will show greater improvement in metabolic control of their diabetes than will adolescents who receive only traditional diabetes instruction. Thirty-four adolescents between the ages of 12 and 16 who attended a midwestern camp were randomly divided into two groups. Both groups attended a daily 1-hour teaching session about diabetes. Later each day, the experimental group received an SLI consisting of role modeling to help the subjects circumvent peer pressure. To determine metabolic control, HbA1 values were determined before and 3 1/2 months after the intervention. The control group showed no significant difference in HbA1 values, while the experimental group showed a decrease in metabolic control.  相似文献   
994.
995.
Gram negative endotoxins play a contributory role in the syndrome which results from over consumption of carbohydrates by horses and ponies. Since the antibiotic polymyxin B exerts a direct anti-endotoxin effect by chemically modifying the active lipid A moiety of endotoxin, it might be expected to protect horses after carbohydrate overload and provide a new therapeutic and experimental tool for this condition. The present study was undertaken to evaluate the effect of polymyxin B on hemostatic, hemodynamic, acid-base, and clinical aspects of the syndrome resulting from carbohydrate overload. Experimentally-induced carbohydrate overload resulted in lactic acidosis, hypercoagulability, hypovolemic shock and lameness. Although there was a slight delay in the onset of clinical signs resulting from experimental carbohydrate overload in treated animals, polymyxin B administered iv at 2.5 mg/kg every 6 hr failed to significantly ameliorate the coagulopathy, acidosis, lameness and shock induced by alimentary carbohydrate overload.  相似文献   
996.
The authors studied the clinical features and outcome at 6 months in 191 patients with subarachnoid hemorrhage (SAH) from ruptured aneurysms. Aneurysm repair (AR) was undertaken in 123 cases (64.4%). In the non-AR group (n = 68), 48.5% of the patients were 70 years of age or older, compared with 12.2% in the AR group. The duration from onset to admission was less than 3 hours in 48 non-AR cases (70.6%) and in 42 AR cases (34.1%). Among non-AR patients, 63.2% were Hunt and Hess grade IV or V, whereas the figure for AR patients was only 14.7%. By 6 months after SAH, 94.1% of non-AR patients had died, and the remainder were vegetative or severely disabled. In contrast, only 15.4% in the AR group died, and over 50% showed good recovery. The large majority of non-AR patients were treated conservatively because they were judged to be poor surgical risks and, among these patients, nearly one half were elderly. In the 10 elderly patients considered good surgical candidates, vasospasm was the most common reason (70%) for not performing AR.  相似文献   
997.
Herniation of a thoracic disc in an acromegalic giant is reported. Degenerative changes in the spine in association with dorsal kyphosis, and the additional strain, resulted in the disc prolapse.  相似文献   
998.
999.
1000.
Catecholamine (CA) release was measured in vivo in the monkey and cat visual cortices electrochemically. Stereate-modified, graphite-paste electrodes were used to monitor changes in norepinephrine and dopamine release. Micromolar changes in CA concentration were obtained by stimulation of the eye with nonspecific (strobe) or specific (oriented bars, radial gratings) stimuli. CA release depended on which eye was illuminated. Electrodes passed tangentially through the striate area recorded release following visual stimulation of one eye or the other in succession, and the shift in eye dominance occurred at about 500 microns intervals. The magnitude of CA release was highly correlated with the ocular dominance of neuronal activity measured with tungsten microelectrodes. Light-stimulated release was not recorded in monkey area V2, V4, or somatosensory area 1, but was recorded in cat V2, suggesting that the presence of LGN afferents is associated with CA release. Results are discussed in terms of the role of geniculate activity and the specific role of CAs in cortical information processing.  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