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   8121篇
  免费   627篇
  国内免费   15篇
耳鼻咽喉   22篇
儿科学   275篇
妇产科学   241篇
基础医学   1125篇
口腔科学   90篇
临床医学   1324篇
内科学   1325篇
皮肤病学   140篇
神经病学   735篇
特种医学   181篇
外科学   730篇
综合类   118篇
一般理论   22篇
预防医学   1081篇
眼科学   245篇
药学   603篇
中国医学   11篇
肿瘤学   495篇
  2024年   13篇
  2023年   93篇
  2022年   105篇
  2021年   217篇
  2020年   177篇
  2019年   271篇
  2018年   297篇
  2017年   226篇
  2016年   241篇
  2015年   259篇
  2014年   357篇
  2013年   484篇
  2012年   668篇
  2011年   658篇
  2010年   362篇
  2009年   312篇
  2008年   506篇
  2007年   551篇
  2006年   498篇
  2005年   513篇
  2004年   470篇
  2003年   444篇
  2002年   346篇
  2001年   66篇
  2000年   43篇
  1999年   61篇
  1998年   76篇
  1997年   60篇
  1996年   54篇
  1995年   46篇
  1994年   44篇
  1993年   46篇
  1992年   23篇
  1991年   20篇
  1990年   15篇
  1989年   6篇
  1988年   16篇
  1987年   5篇
  1986年   7篇
  1985年   14篇
  1984年   17篇
  1982年   10篇
  1981年   6篇
  1980年   6篇
  1979年   5篇
  1978年   7篇
  1977年   6篇
  1974年   5篇
  1973年   7篇
  1971年   7篇
排序方式: 共有8763条查询结果,搜索用时 0 毫秒
71.
72.
73.
Wolcott-Rallison syndrome is a rare autosomal recessive condition characterized by diabetes mellitus arising in early infancy and multiple epiphyseal dysplasia. To date, nine cases have been described in the world literature. We report an affected girl who died at the age of 4 years and on whom a full autopsy was performed. In addition to neonatal diabetes mellitus and epiphyseal dysplasia, this child had mental retardation and recurrent episodes of self-limiting hepatic failure. Autopsy revealed severe pancreatic hypoplasia and markedly abnormal pancreatic histology, while histology of the bone was consistent with epiphyseal dysplasia. There was laryngeal stenosis and pulmonary hypoplasia. The heart was enlarged with mitral valve dysplasia and stenosis, left atrial dilatation, left ventricular hypertrophy, and endocardial fibroelastosis. Examination of the central nervous system showed arrhinencephaly and cerebellar cortical dysplasia. The liver showed minor histological abnormalities but no features were present to account for the recurrent hepatic failure. In addition to Wolcott-Rallison syndrome this child had a deletion at 15q11-12 in 65 of her cells.  相似文献   
74.
Objective To describe changes in the maternal cerebral circulation and the external iliac arteries throughout pregnancy and the puerperium using the Laplace transform analysis of Doppler waveforms.
Design A prospective longitudinal study.
Setting Department of Obstetrics and Gynaecology, Nottingham University Hospital.
Sample A cohort of 17 healthy women studied every four weeks from early pregnancy until term and up to three months postpartum. Pre-conception data were available for 10 subjects.
Methods Doppler signals were recorded from the internal carotid, middle cerebral and external iliac arteries. The waveforms were analysed using two different techniques: standard indices (systolic: diastolic ratio, pulsatility and resistance indices) and Laplace transform analysis, an alternative method of waveform shape analysis which may provide additional haemodynamic information.
Results Vessel wall tone decreased at an early stage in pregnancy in the cerebral circulation and in the external iliac artery, but this rose again following delivery. The Laplace transform analysis techniques suggest dramatic eight-fold increases in downstream resistance within the external iliac artery in the second half of pregnancy. An increase in downstream resistance to flow also occurred in the internal carotid artery whereas more stable conditions were noted in the middle cerebral artery.
Conclusions Having a preliminary idea of the normal ranges for the Laplace transform analysis variables during pregnancy in a variety of maternal vessels, haemodynamic changes in pregnancies complicated by conditions, such as pre-eclampsia, can now be studied.  相似文献   
75.
Although relatively common in adults, leiomyoma of the esophagus is a rare disorder in children. A single case report describes the coexistence of both esophageal and bronchial leiomyoma in a child. The authors describe the diagnostic and treatment challenges encountered in a 2-year-old boy with coexisting inflammatory pseudotumor and esophageal leiomyoma presenting as massive atelectasis.  相似文献   
76.
77.
78.
PURPOSE: Epstein-Barr virus (EBV) in Hodgkin's lymphoma (HL) cells has been considered as a prognostic marker for this heterogeneous disease, but studies have yielded mixed findings, likely because of selected patient series and failure to acknowledge an effect of age on outcome. This study assessed survival after HL in a population-based cohort large enough to examine the joint effects of EBV with other factors including age, sex, and histologic subtype. PATIENTS AND METHODS: Included were 922 patients with classical HL diagnosed between mid-1988 and 1997 in the Greater San Francisco Bay Area, with archived biopsy specimens assayed for EBV with immunohistochemistry and in situ hybridization. Vital status was followed through December 30, 2003 (median follow-up time, 97 months). Overall and disease-specific survival were analyzed with the Kaplan-Meier method and Cox proportional hazards regression models. RESULTS: In children less than 15 years old, EBV presence was suggestively associated (P = .07) with favorable survival. In adults aged 15 to 44 years, EBV did not affect HL outcome, although a protective effect was suggested. In older adults (45 to 96 years), EBV presence nearly doubled the risk of overall and HL-specific mortality but only for patients with nodular sclerosis (NS) histologic subtype (hazard ratio for death = 2.5; 95% CI, 1.5 to 4.3). CONCLUSION: In HL, EBV tumor cell presence is associated with better survival in young patients and poorer survival in older patients with NS, independent of other factors. Variation in outcome by age and histology could indicate biologically distinct disease entities. Evidence that EBV is a meaningful prognostic marker may have therapeutic relevance.  相似文献   
79.
Reported parameters of the MTT assay vary widely, and reflect a need to optimise the assay for different cell types. The MTT assay conditions for the human B-lymphocyte-derived cell line WIL2NS were optimised for MTT incubation and formazan development. The optimised MTT assay was validated by examining the effects of the acaride amitraz on WIL2NS. In pH-buffered media in the absence of cells, MTT formed formazan spontaneously, and absorbance was proportional to both the initial concentration of MTT and the time of incubation at 37 °C. One milligram per millilitre MTT was toxic to WIL2NS cells, but the accuracy of the standard curve was reduced when only 0.2 mg/ml MTT was used. Twenty percent SDS in 0.2 M HCl was preferable to DMSO as a solvent for formazan. Exposure to 0.035% amitraz resulted in a significant reduction in WIL2NS cell numbers after only 2 h of exposure. It was concluded that 0.035% of amitraz has the potential to adversely affect lymphocytes in the systemic blood system in humans, and that an optimised MTT assay was obtained by incubating WIL2NS cells with 0.45 mg/ml MTT for 17 h, followed by addition of acidified SDS for 1 h.  相似文献   
80.
Objectives To assess the feasibility and acceptability of concordance in pharmacy practice through examination of communication between customers and pharmacists in two community pharmacies in consultations for over‐the‐counter medicines. Method A qualitative pilot study involving data drawn from six sources: audiotaped training session with all the pharmacists involved, observational field work in the pharmacies, audiotaped consultations with pharmacists and customers, debriefing interviews with pharmacists after the consultation, and semi‐structured interviews with customers a few days after their consultation. Setting Two community pharmacies that concentrate their services on medicine advice and dispensing, one in a deprived inner‐city area, the other in a more affluent suburban area of London. Key findings The pharmacists developed a personal understanding of concordance which informed their practice. Customers reported a high level of satisfaction with services they received from the respective pharmacists. Their accounts of the consultations verified the pharmacists' patient‐centredness in their day‐to‐day practice. Conclusion The implementation of a concordance model was possible through the development of a personalised, patient‐centred model which drew on the model of concordance but was adapted in accordance with both structural constraints as well as the personal style of the pharmacists involved.  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