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   334篇
  免费   26篇
耳鼻咽喉   1篇
儿科学   19篇
妇产科学   4篇
基础医学   47篇
口腔科学   4篇
临床医学   29篇
内科学   95篇
皮肤病学   29篇
神经病学   22篇
特种医学   6篇
外科学   33篇
综合类   10篇
预防医学   18篇
眼科学   11篇
药学   28篇
肿瘤学   4篇
  2023年   2篇
  2021年   1篇
  2019年   3篇
  2018年   3篇
  2017年   6篇
  2016年   9篇
  2015年   11篇
  2014年   7篇
  2013年   8篇
  2012年   12篇
  2011年   16篇
  2010年   20篇
  2009年   18篇
  2008年   14篇
  2007年   21篇
  2006年   25篇
  2005年   13篇
  2004年   11篇
  2003年   6篇
  2002年   14篇
  2001年   10篇
  2000年   11篇
  1999年   16篇
  1998年   8篇
  1997年   11篇
  1996年   14篇
  1995年   7篇
  1994年   8篇
  1993年   6篇
  1992年   10篇
  1991年   4篇
  1990年   8篇
  1988年   2篇
  1987年   1篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1981年   1篇
  1980年   2篇
  1977年   2篇
  1976年   1篇
  1967年   1篇
  1959年   3篇
  1958年   2篇
  1957年   1篇
  1955年   2篇
  1954年   5篇
排序方式: 共有360条查询结果,搜索用时 31 毫秒
1.
Laparoscopic surgery has several advantages over traditional surgery because it has been shown to be less invasive. The next logical step in the evolution of minimally invasive surgery may be to eliminate all abdominal incisions. The natural orifices provide a port of entry via the gastrointestinal tract to the peritoneal cavity. This approach would require the creation of a perforation, which is considered to be a major complication of endoscopy with significant morbidity and mortality. However, there are several recent studies that have described the technical feasibility and safety of a per‐oral transgastric approach to the peritoneal cavity using conventional endoscopes. Theoretically, this approach could reduce postoperative abdominal wall pain, wound infection, hernia formation, and adhesions. This article aims to summarize the current status of transgastric surgery, currently referred to as natural orifice transluminal endoscopic surgery (NOTES), and to address some of its future challenges.  相似文献   
2.
Occupational exposure to carcinogenic agents on the decks on six Norwegian crude oil tankers was examined in five harbors. The purpose of the study was to evaluate the need for improving the working environment on deck on these tankers. Technical arrangments and the work itself on the deck were observed during loading or unloading. Occupational monitoring was performed by active sampling of benzene, polyaromatic hydrocarbons, and some aldehydes. The crew answered a questionnaire concerning their work, use of protective equipment, and occurrence of acute symptoms. The levels of air-borne carcinogenic agents were low, probably due to closed loading systems on all tankers. However, the seamen reported discomfort during the work that may be related to other chemical agents in the cargo. The seamen were frequently painting with lead chromate paint without using personal protective equipment. This type of chemical exposure should be evaluated.  相似文献   
3.
Abstract: The plasma ratio of each neutral amino acid (tryptophan (TRP), tyrosine (TYR), valine, isoleucine, leucine (LEU) or phenylalanine) to the sum of the other neutral amino acids was measured in 16 : manic and 14 : depressed patients. In the manics, there was a correlation between the psychomotor activity and the plasma TRP and LEU ratios. In the depressives, the depressed mood, retardation and global severity were correlated with the TRP ratio. The zotepine responders showed an increase in the TRP ratio after treatment. In the mianserin responders, the TYR ratio, which was high before the treatment, decreased to the normal range after the treatment. But, the plasma amino acid ratios remained unchanged in the patients treated with lithium carbonate or amitriptyhe. These results suggest that, in manic-depressive illness, there might be abnormalities in the metabolism of neutral amino acids, mainly of TRP and TYR, and that the plasma TRP and TYR ratios might be important indicators for determining the efflcacy of some drugs.  相似文献   
4.
5.
BACKGROUND: A previous study demonstrated a higher rate of schizophrenia in dizygotic twins than in the general population, and a higher rate of schizophrenia in siblings of dizygotic twins than in siblings of monozygotic twins and singletons, pointing to a common genetic predisposition for dizygotic twinning and schizophrenia. The aim of the present study was to investigate whether these findings also apply to bipolar disorder. METHODS: Through record linkage between The Danish Twin Register, The Danish Psychiatric Central Register and The Danish Civil Registration System, the rate of bipolar disorder (diagnosed for the first time during admission to hospital) in dizygotic and monozygotic twins was compared with the rate in singletons, and the rate in siblings and parents of twins was compared with the rate in siblings and parents of singletons. RESULTS: The rate of bipolar disorder was the same in dizygotic twins, monozygotic twins and singletons as well as for parents and siblings of dizygotic twins, monozygotic twins and singletons. LIMITATIONS: The study is a register-based study, only including hospitalized patients. CONCLUSION: This study shows that there is an equal rate of bipolar disorder in twins and in singletons. Assuming that DZ twinning is under some genetic influence, a differential relationship between schizophrenia and DZ twinning on one hand and bipolar disorder and DZ twinning on the other hand may suggest differences in the genetic basis of the two diseases. The finding that the rate of bipolar disorder in monozygotic twins is the same as the rate of bipolar disorder in singletons supports studies finding no association between bipolar disorder and obstetric complications.  相似文献   
6.
Type 1 diabetes has been associated with an increased frequency of activated T cells and T-cell hyperactivity to non-specific and disease-specific stimuli including the islet autoantigen glutamic acid decarboxylase 65 (GAD). To address whether T-cell hyperactivity is genetic or acquired we measured whole blood cytokines in vitro in response to GAD or tetanus in 18 identical twin pairs, nine discordant for type 1 diabetes. In addition, the activity of 2', 5' oligoadenylate synthetase (OAS) in blood mononuclear cells was measured as a marker of viral infection. Interleukin-2 (IL-2) basally and IL-2 and interferon-gamma (IFN-gamma) in response to GAD, were detected more frequently and at higher levels in diabetic compared to non-diabetic twins. IL-10 was not different between groups. OAS activity was increased in diabetic compared to non-diabetic twins and showed a correlation with basal IL-2 and GAD-stimulated IFN-gamma and IL-10. These findings suggest that T-cell hyperactivity in type 1 diabetes is an acquired trait and could reflect persisting virus expression.  相似文献   
7.
BACKGROUND: Twin studies have concluded that there is a substantial genetic contribution to the aetiology of eating disorders. The aim of the present study was to estimate the genetic contribution to the aetiology of self-reported eating disorders in a sample of representative twins. METHOD: A population cohort of 34142 young Danish twins was screened for eating disorders by a mailed questionnaire. RESULTS: Concordance rates differed significantly across monozygotic and dizygotic twin pairs for broadly defined self-reported anorexia nervosa and bulimia nervosa. Heritability estimates of 0.48, 0.52 and 0.61 respectively were estimated for narrow and broad definitions of self-reported anorexia nervosa and for self-reported bulimia nervosa. CONCLUSIONS: There is a genetic contribution to the aetiology of self-reported eating disorders in the general population. The relationship between self-reported and clinical eating disorder remains to be examined.  相似文献   
8.
It has recently been proposed that occupational exposure to organic solvents in vivo may lead to platelet activation and this has been substantiated by exposure of platelets to solvents in vitro. The present work was undertaken to study the effects of organic solvents on the platelet inositol lipid signal transduction system. Human platelets that had been prelabelled with [(32)P] P, were exposed to a saturated atmosphere of the organic solvents toluene, xylene or hexane. Extracts were analyzed for metabolites of the polyphosphoinositide cycle and ATP. All solvents studied induced a decrease in radioactivity in phosphatidylinositol 4,5-bisphosphate together with an increase in radioactivities in phosphatidylinositol 4-phosphate and phosphatidic acid. This is compatible with solvent-induced activation of the cells through the inositol lipid pathway. In cells exposed to toluene or xylene we could detect an increased level in inositol trisphosphates at 3 min of exposure. The solvent-induced changes in metabolic ATP could not explain the solvent-induced effects on the inositol lipid metabolism. It is concluded that the organic solvents toluene, xylene and hexane can activate human platelets through the inositol lipid-linked transmembrane signal system.  相似文献   
9.
We report a case of Takayasu's disease with severe renovascular hypertension in a girl from Eritrea. In the "burn-out" phase after the erythrocyte sedimentation rate had normalized, reconstructive vascular surgery was performed as further progression of the disease seemed unlikely. However, probably due to her growth, the graft rotated and a second operation was successfully performed.  相似文献   
10.
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