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   7765篇
  免费   276篇
  国内免费   24篇
耳鼻咽喉   65篇
儿科学   167篇
妇产科学   2871篇
基础医学   511篇
口腔科学   213篇
临床医学   808篇
内科学   1262篇
皮肤病学   45篇
神经病学   366篇
特种医学   110篇
外科学   448篇
综合类   27篇
预防医学   368篇
眼科学   9篇
药学   393篇
中国医学   22篇
肿瘤学   380篇
  2021年   86篇
  2019年   77篇
  2018年   92篇
  2017年   81篇
  2016年   81篇
  2015年   98篇
  2014年   117篇
  2013年   195篇
  2012年   266篇
  2011年   273篇
  2010年   143篇
  2009年   197篇
  2008年   270篇
  2007年   257篇
  2006年   228篇
  2005年   268篇
  2004年   235篇
  2003年   205篇
  2002年   199篇
  2001年   148篇
  2000年   119篇
  1999年   192篇
  1998年   205篇
  1997年   243篇
  1996年   236篇
  1995年   179篇
  1994年   189篇
  1993年   124篇
  1992年   178篇
  1991年   215篇
  1990年   111篇
  1989年   170篇
  1988年   144篇
  1987年   101篇
  1986年   146篇
  1985年   142篇
  1984年   103篇
  1983年   124篇
  1982年   116篇
  1981年   91篇
  1980年   81篇
  1979年   85篇
  1978年   77篇
  1977年   76篇
  1976年   76篇
  1975年   86篇
  1974年   74篇
  1973年   103篇
  1972年   74篇
  1970年   79篇
排序方式: 共有8065条查询结果,搜索用时 0 毫秒
1.
BACKGROUND: In the central nervous system, several neuropeptides are believed to be involved in the pathophysiology of Alzheimer's disease (AD). Indeed, previous studies have documented that glucagon-like peptide 1 (GLP-1) possesses neurotropic properties and can reduce amyloid-beta peptide levels in the brain in vivo. Moreover, the concentrations of neuropeptide Y (NPY) seem to be altered in the cerebrospinal fluid of patients with AD and in subjects with major depression. Finally, among the modifications induced by aging, a dysregulation of the ghrelin-growth hormone (GH) system has been reported. METHODS: We investigated the plasma concentrations of these neuropeptides in 14 subjects with AD. Data obtained from these patients were compared with data from an age- and weight-matched healthy group. RESULTS: No significant differences were found between the two groups in relation to plasma levels of GLP-1, NPY, ghrelin and GH. Peripheral NPY concentrations were positively correlated with ghrelin levels in both groups, and with plasma GLP-1 concentration only in controls. CONCLUSION: On the basis of our results, peripheral levels of these neuropeptides seem not to serve as biochemical markers of AD.  相似文献   
2.
Coagulation screening before epidural analgesia in pre-eclampsia   总被引:1,自引:0,他引:1  
A questionnaire survey of current practice at a small cross-section of obstetric units, covering 22% of all United Kingdom deliveries, revealed a marked lack of standard practice regarding requests for coagulation screens on pre-eclamptic patients who require epidural procedures. A retrospective audit was therefore carried out on 434 coagulation screens requested for pre-eclamptic patients in whom epidural analgesia might have been considered. Borderline abnormalities of coagulation were found in only 10 patients (2%). Platelet counts of less than 150 x 10(9)/litre were present in 28% of cases. 'Significant' thrombocytopenia (less than 100 x 10(9)/litre) and all coagulation abnormalities were only encountered in severe pre-eclampsia (diastolic blood pressure of greater than 110 mmHg and proteinuria of + + or greater). Furthermore, coagulation abnormality was always associated with a reduced platelet count (mean, 97 x 10(9)/litre). This study would therefore support anaesthetic practice which restricted any requests for coagulation testing to severe pre-eclamptic patients only. For these patients first line testing could be limited to a platelet count.  相似文献   
3.
4.
Several attempts have been made to enhance doxorubicin (DOXO) concentrations in tumour cells by drug conjugation with human albumin (HSA). HSA-DOXO has the drawback of causing DOXO accumulation in spleen and bone marrow, with a consequent leucopoenia not produced when lactose molecules are coupled to the carrier protein. In the present experiments we demonstrated that the effect of HSA lactosamination is not a consequence of a more rapid disappearance from the bloodstream of the lactosaminated conjugate (L-HSA-DOXO), which is rapidly internalized by the liver through the asialoglycoprotein receptor, but is due to a hindered uptake by spleen and bone marrow cells caused by the coupled lactose molecules. Experiments in vitro showed that HSA-DOXO produced an inhibition of murine macrophage proliferation not caused by L-HSA-DOXO. This result can be explained by higher amounts of the former conjugate entering in these cells and suggests macrophages as the cell type responsible for the spleen and bone marrow internalization of HSA-DOXO hindered by lactose coupling. Importantly, lactosamination of HSA did not reduce the marked uptake of HSA-DOXO by chemically induced rat hepatocellular carcinoma. L-HSA-DOXO, by avoiding DOXO accumulation in bone marrow is an attractive candidate for clinical trials against tumors which were found to actively internalize this conjugate in laboratory animals, such as hepatocellular carcinoma.  相似文献   
5.
Urinary tract injuries during obstetric intervention   总被引:11,自引:0,他引:11  
A retrospective case record review of obstetric urinary tract injury in the Grampian region from 1976 to 1993 identified 16 cases of bladder injury (0.1 per 1000 deliveries, 1.4 per 1000 caesarean sections and four cases of ureteric injury (0.03 per 1000 deliveries, 0.27 per 1000 caesarean sections). Diagnosis of bladder injury was immediate, but of ureteric injury often delayed. Although the injury rates are lower than previously reported and previously reported risk factors not confirmed, this audit has resulted in guidelines for junior staff, compliance with which will be monitored, and every case of urinary tract injury will be reviewed.  相似文献   
6.
This case report describes infantile nephrotic syndrome (NS) in a baby girl with a clinically severe cytomegalovirus (CMV) infection. Culture of the baby's urine was positive for CMV and IgM anti-CMV antibodies were detected. After an unsuccessful course of corticosteroids, gancyclovir treatment was started and a remission of cutaneous, pulmonary, and renal symptoms was achieved. As the mother also developed NS at the end of pregnancy, a common etiology could be postulated, although there were no signs of recent CMV infection in the mother, only anti-CMV IgG. The relationship between CMV infection and glomerular disease is still unclear: NS may represent another manifestation of CMV disease.  相似文献   
7.
The research describes how nursing staff on a general surgical ward in a district general hospital perceived the delivery method of nursing care in practice. The study design was based on ethnographic methods and data were collected by diary keeping and semi-structured interviews. An organizational method based on the principles of primary nursing had been implemented on the ward for 2 years prior to the study commencing. As well as talking in general terms about primary nursing, the nursing staff talked at some length about specific issues related to their practice.  相似文献   
8.
9.
10.
Reversal of sterilisation by the railroad technique   总被引:1,自引:0,他引:1  
Objective To show that a simple, easily learned and relatively inexpensive method of reversal of sterilisation provides good results.
Design Retrospective observational study.
Setting An NHS Trust Hospital.
Sample Sixty-seven women aged 19 to 39 years who underwent reversal of sterilisation between January 1984 and December 1993.
Main outcome measures Pregnancy rate following reversal; rate of ectopic pregnancy.
Results Thirty-four women (51%) had intrauterine pregnancies after reversal of sterilisation; intrauterine pregnancy rate in women who had been sterilised with rings or clips was 64%. Five women (7.5%) had ectopic pregnancies.
Conclusion This technique provides results that compare favourably with those of microsurgery. It offers hope to couples who do not meet the restrictive criteria for microsurgery and in vitro fertilisation and should appeal to purchasing authorities.  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