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   3390114篇
  免费   250976篇
  国内免费   8996篇
耳鼻咽喉   45738篇
儿科学   110531篇
妇产科学   92188篇
基础医学   476160篇
口腔科学   94841篇
临床医学   310638篇
内科学   667426篇
皮肤病学   77636篇
神经病学   280256篇
特种医学   131627篇
外国民族医学   952篇
外科学   506684篇
综合类   72841篇
现状与发展   5篇
一般理论   1295篇
预防医学   266771篇
眼科学   75211篇
药学   248015篇
  11篇
中国医学   6647篇
肿瘤学   184613篇
  2019年   26610篇
  2018年   37441篇
  2017年   28747篇
  2016年   33058篇
  2015年   37288篇
  2014年   51732篇
  2013年   77920篇
  2012年   103333篇
  2011年   109531篇
  2010年   65963篇
  2009年   63104篇
  2008年   102046篇
  2007年   108617篇
  2006年   110290篇
  2005年   106100篇
  2004年   102297篇
  2003年   98475篇
  2002年   94886篇
  2001年   162130篇
  2000年   166496篇
  1999年   140109篇
  1998年   40609篇
  1997年   36110篇
  1996年   36552篇
  1995年   35519篇
  1994年   32739篇
  1993年   30630篇
  1992年   110439篇
  1991年   106621篇
  1990年   103282篇
  1989年   99406篇
  1988年   91343篇
  1987年   89756篇
  1986年   84435篇
  1985年   80686篇
  1984年   60476篇
  1983年   51157篇
  1982年   30431篇
  1981年   27263篇
  1979年   53915篇
  1978年   38310篇
  1977年   32354篇
  1976年   30032篇
  1975年   32048篇
  1974年   38027篇
  1973年   36275篇
  1972年   33881篇
  1971年   31446篇
  1970年   28913篇
  1969年   27512篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
962.
963.
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   
964.
965.
PURPOSE: To provide a model for assessing occupational therapy workforce needs by using a demand-based approach to determine current workforce status in the Northwest region. Regional information may have implications for addressing national occupational therapy service needs. METHOD: A questionnaire was sent to a proportional random sample of 234 facilities that hire occupational therapy practitioners. Data were collected in July-August 2003 using structured mailing and follow-up procedures. RESULTS: Response rate was 79%. Twenty-four percent reported occupational therapy vacancies and 11% occupational therapy assistant vacancies; 48% predicted an increase in occupational therapy positions in the next 2 years and 41% an increase in occupational therapy assistant positions. Sixty-three percent of respondents reported difficulty in hiring. DISCUSSION: This study identifies an occupational therapy workforce shortage in the Northwest. Management of a shortage is critical, for even short-term adjustments could lead to permanent changes in service provision. This study demonstrates the importance of current information on the status of the national workforce and serves as a model for future studies.  相似文献   
966.
967.
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   
968.
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   
969.
970.
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