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   2580600篇
  免费   209281篇
  国内免费   7694篇
耳鼻咽喉   34533篇
儿科学   84954篇
妇产科学   72200篇
基础医学   360600篇
口腔科学   74632篇
临床医学   231338篇
内科学   513077篇
皮肤病学   58517篇
神经病学   211513篇
特种医学   104417篇
外国民族医学   720篇
外科学   396193篇
综合类   63522篇
现状与发展   5篇
一般理论   912篇
预防医学   205460篇
眼科学   57449篇
药学   187914篇
  8篇
中国医学   4591篇
肿瘤学   135020篇
  2018年   25088篇
  2016年   22813篇
  2015年   26030篇
  2014年   36195篇
  2013年   54793篇
  2012年   70297篇
  2011年   74827篇
  2010年   45594篇
  2009年   43988篇
  2008年   70893篇
  2007年   75208篇
  2006年   76714篇
  2005年   74369篇
  2004年   72256篇
  2003年   69751篇
  2002年   67240篇
  2001年   120212篇
  2000年   123901篇
  1999年   104366篇
  1998年   30405篇
  1997年   27477篇
  1996年   28119篇
  1995年   27837篇
  1994年   26151篇
  1993年   24573篇
  1992年   86987篇
  1991年   84755篇
  1990年   82079篇
  1989年   78999篇
  1988年   73490篇
  1987年   72360篇
  1986年   68546篇
  1985年   66267篇
  1984年   50215篇
  1983年   42798篇
  1982年   26061篇
  1981年   23421篇
  1980年   22071篇
  1979年   46908篇
  1978年   33319篇
  1977年   28189篇
  1976年   26233篇
  1975年   27654篇
  1974年   33301篇
  1973年   32015篇
  1972年   29484篇
  1971年   27572篇
  1970年   25307篇
  1969年   23781篇
  1968年   21868篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
Multiple intrahippocampal injections of gallamine impair performance of a representational memory task in rats. The binding of [3H]-(-)-quinuclidinyl benzilate (QNB) to rat brain sections was measured to determine if changes in receptor binding were associated with the deleterious effects of gallamine. [3H]-(-)-QNB binding to sections taken from gallamine-injected animals was compared with binding in saline-injected control animals. Autoradiographic analyses indicated an increase in [3H]-(-)-QNB binding sites within all layers of the cerebral cortex and in the superior colliculus in gallamine-treated animals as compared to saline-injected controls. Significant increases were noted in cortical layers IV and V (P less than 0.025) in gallamine-treated animals. No significant changes (P greater than 0.05) in the number of binding sites were observed in the hippocampus, neostriatum or various thalamic nuclei. The ability of unlabeled pirenzepine, gallamine and carbamylcholine to inhibit 0.2 nM [3H]-(-)-QNB binding also was measured to determine changes in the distribution of receptor subtypes. No significant changes were observed in any brain region for the binding of the selective antagonists pirenzepine and gallamine or the agonist carbamyl-choline. Although other possibilities are considered, the data suggest that an increase in the number of muscarinic receptors may contribute to the observed behavioral deficits associated with long-term gallamine treatment.  相似文献   
995.
996.
997.
The literature suggests that pain in the elderly, especially among seniors with dementia, is under-assessed and under-treated.This qualitative study solicited the perspectives of seniors, front-line nursing staff, nursing-home administrators, and informal caregivers of seniors with dementia on the current status of pain assessment and management. The views of these participants complement the research findings reported in the literature. While some of their explanations and potential solutions concerning under-treatment of pain in seniors echo views that have been presented in the literature, the participants also pointed to factors and avenues that have been given less formal consideration (e.g., systemic barriers to effective assessment and treatment of pain).They also highlighted the need for pain-control strategies beyond medication. The implications of these findings are discussed.  相似文献   
998.
The microfracture technique and spongiolization using Pridie drilling are the most commonly used and highly cost-efficient operative therapies for restoration of cartilage in Germany. Microfracturing can be performed arthroscopically in various joints including the knee, ankle, elbow, and shoulder joint. Specifically designed instruments are recommended for this procedure. Steadman recently reported excellent results in a series of 72 patients undergoing microfracturing with a mean follow-up of 11 years showing consistent and long-term reduction of weight-bearing pain and swelling as well as improvement of daily activities. Ideal indications for this easy arthroscopic procedure of microfracture treatment include focal lesions up to 4 cm2. Some studies have demonstrated that microfracturing results not merely in the formation of fibrocartilage but also in the induction of hyaline cartilage with superior properties.  相似文献   
999.
OBJECTIVE: To describe the course and outcome of fetuses with absent or reversed end-diastolic (ARED) flow in the umbilical artery (UA) and to examine the influence of prematurity according to gestational age at delivery. METHODS: Sixty pregnancies complicated by ARED flow in the UA were monitored by repeat Doppler measurements of arterial and venous vessels, non-stress tests (cardiotocogram (CTG)) and maternal investigations, and were delivered between 24 and 34 weeks. Fetal outcome was investigated and compared to a control group of appropriate-for-gestational age (AGA) preterm neonates, matched for gestational age. Mortality, birth weight, Apgar scores, postnatal cord arterial pH and need for ventilation were all recorded, as were cases of respiratory distress syndrome, bronchopulmonary dysplasia, persistent ductus arteriosus, necrotizing enterocolitis, intraventricular hemorrhage, periventricular leukomalacia, abnormal neurological findings and those requiring surgical intervention. Additionally, the group of fetuses with ARED flow was divided into three subgroups of different degrees of prematurity (delivery between 24 + 0 and 28 + 6 weeks, delivery between 29 + 0 and 31 + 6 weeks, and delivery after 32 weeks) and compared according to the above parameters. RESULTS: Pre- or postnatal death occurred in 16 cases. Comparing the 44 (61%) that were born alive with the AGA neonates, significant differences were found in birth weight (P < 0.001), arterial pH value (P < 0.001), bronchopulmonary dysplasia (P = 0.002) and intestinal complications (P < 0.01). Prematurity-related complications were: need for ventilation (P = 0.001), respiratory distress syndrome (P < 0.0001), periventricular leukomalacia (P = 0.002) and pathological neurological testing (P = 0.005). CONCLUSIONS: Neonates displaying ARED flow before birth are growth restricted, acidemic at delivery and are at high risk of developing bronchopulmonary dysplasia and intestinal complications. While perinatal mortality seems to be related to abnormal fetal Doppler velocimetry, age at delivery has a significant impact on short-term morbidity. After 32 weeks, morbidity is low and delivery should be considered. It could be speculated from our data that prolongation of pregnancy with Doppler velocimetry monitoring could help to reduce morbidity, although prolongation remains limited in most cases.  相似文献   
1000.
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