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   557篇
  免费   37篇
  国内免费   9篇
儿科学   36篇
妇产科学   1篇
基础医学   52篇
口腔科学   2篇
临床医学   30篇
内科学   168篇
皮肤病学   6篇
神经病学   8篇
特种医学   74篇
外科学   36篇
综合类   57篇
预防医学   30篇
药学   81篇
中国医学   2篇
肿瘤学   20篇
  2022年   2篇
  2021年   4篇
  2019年   3篇
  2016年   2篇
  2015年   2篇
  2014年   9篇
  2013年   8篇
  2012年   15篇
  2011年   19篇
  2010年   20篇
  2009年   9篇
  2008年   21篇
  2007年   27篇
  2006年   21篇
  2005年   16篇
  2004年   26篇
  2003年   16篇
  2002年   8篇
  2001年   17篇
  2000年   14篇
  1999年   17篇
  1998年   38篇
  1997年   29篇
  1996年   24篇
  1995年   19篇
  1994年   20篇
  1993年   17篇
  1992年   15篇
  1991年   14篇
  1990年   16篇
  1989年   20篇
  1988年   18篇
  1987年   10篇
  1986年   15篇
  1985年   10篇
  1984年   9篇
  1983年   3篇
  1982年   7篇
  1981年   7篇
  1980年   6篇
  1979年   3篇
  1978年   4篇
  1976年   2篇
  1975年   3篇
  1967年   2篇
  1947年   2篇
  1945年   1篇
  1944年   2篇
  1943年   2篇
  1926年   1篇
排序方式: 共有603条查询结果,搜索用时 46 毫秒
41.
Adverse reactions in blood donors with a history of seizures or epilepsy   总被引:1,自引:0,他引:1  
BACKGROUND: Individuals with epilepsy or seizure disorders are restricted from donating blood because of concern that they are prone to adverse donor reactions such as syncope and convulsions. A study evaluating whether that concern is warranted is reported. STUDY DESIGN AND METHODS: During a 2-year period beginning in 1987, blood donors in Maryland with a history of seizures were actively recruited by the American Red Cross. Adverse donor reactions were classified as "slight", indicating dizziness and nausea without loss of consciousness; "moderate," denoting syncope; and "severe," indicating convulsive syncope. RESULTS: There were 329,143 satisfactory blood donations; 613 individuals reporting a history of seizures donated blood a total of 723 times. Among donors with seizures, 186 (35.7%) were taking antiepileptic medication, and 61 (8.4%) had had one or more seizures in the preceding year. Individuals with seizures had a low incidence of adverse reactions (3.34%). Although this incidence was slightly higher than that in the entire population (2.24%), the difference was not significant. In particular, the risk of syncope with or without convulsive activity was low for people with seizures (0.21%) and not significantly greater than that in other donors (0.28%). CONCLUSION: Individuals with seizures or epilepsy are not at greater risk for adverse reactions after blood donation, and major restrictions on their participation as blood donors are not warranted.  相似文献   
42.
43.
44.
45.
Gastroesophageal reflux disease (GERD) is one of the most prevalent diseases worldwide, and it is becoming increasingly important to monitor the effect of various interventions on GERD symptoms. There can be rapid temporal changes in the severity and frequency of patients' symptoms as well as their health status and well-being, all of which could, theoretically, be monitored using diaries or questionnaires. However, current GERD monitoring instruments are not appropriate because they do not assess symptoms daily, they are not sufficiently responsive to short-term changes in health status or they are not adequately validated. To address these problems, the conceptual and psychometric requirements for a GERD symptom assessment questionnaire were identified. A dimension-based scale was designed to reduce the number of symptoms monitored on a daily basis, and the validation process was defined to produce parallel long and short forms of a scale for patients' self-assessment of their GERD symptom response to therapy. These basic principles which underlie the successful development of a new, self-assessed symptomatic reflux questionnaire (ReQuest) are also applicable to the development of validated questionnaires for daily symptom self-assessment in other disease areas.  相似文献   
46.
47.

Background  

It has recently been shown that overexpression of the serine protease, matriptase, in transgenic mice causes a dramatically increased frequency of carcinoma formation. Overexpression of HAI-1 and matriptase together changed the frequency of carcinoma formation to normal. This suggests that the ratio of matriptase to HAI-1 influences the malignant progression. The aim of this study has been to determine the ratio of matriptase to HAI-1 mRNA expression in affected and normal tissue from individuals with colorectal cancer adenomas and carcinomas as well as in healthy individuals, in order to determine at which stages a dysregulated ratio of matriptase/HAI-1 mRNA is present during carcinogenesis.  相似文献   
48.
BACKGROUND/AIMS: The aim of this study was to determine the one-year outcome of an eradication therapy with ranitidine bismuth citrate and antibiotics in Helicobacter pylori-positive duodenal ulcer patients in respect to ulcer and Helicobacter pylori relapse rates. METHODOLOGY: This multicenter, randomized, double-blind study involved 648 duodenal ulcer patients and had been carried out to compare the following regimens: ranitidine bismuth citrate b.i.d. co-prescribed with either clarithromycin 250 mg q.i.d. or clarithromycin 500 mg b.i.d. or clarithromycin 500 mg b.i.d. plus metronidazole 400 mg b.i.d. for 2 weeks, followed by a further 14 days of treatment with ranitidine bismuth citrate 400 mg b.i.d. to facilitate ulcer healing. H. pylori eradication was assessed by 13C-urea breath test and histology at least 4 weeks, 26 weeks and 52 weeks after the end of treatment. Ulcer relapse and H. pylori status were assessed 4 weeks, 26 weeks and 52 weeks post-treatment or if ulcer symptoms recurred. For the remainder of the follow-up period only serious adverse events were collected. RESULTS: At 12 months data of 438 (69%) patients were evaluable. The observed H. pylori eradication rates were 88-91%. H. pylori relapse rates were 2.1% after 26 weeks and 3.9% after 52 weeks. At the week 26 visit 26 patients (5.6%) and at the week 52 visit 25 patients (5.7%) had documented gastroesophageal reflux disease. CONCLUSIONS: Our data confirm the reduction of duodenal ulcer relapses after the cure of Helicobacter pylori infection.  相似文献   
49.
INTRODUCTION: We previously demonstrated that 60% ethanol increased macromolecular leakage and induced lesion formation in areas of permanent flow stasis within gastric mucosal vessels. Mast cells and their mediators have been implicated in acute mucosal injury. Fluorescent in vivo microscopy was used to assess the effects of ketotifen, a mast cell stabilizer, and pyrilamine, a histamine (H1)-receptor antagonist, on ethanol-induced rat gastric mucosal injury. METHODS: Experiments were carried out on anaesthetized rats pretreated orally with ketotifen (1 mg/kg) or pyrilamine (30 mg/kg). Fluorescein isothiocyanate-bovine serum albumin (FITC-BSA; 0.2 mL/100 g), a marker for quantitating macromolecular leakage was administered intra-arterially. Ethanol (60%) or distilled water was applied topically to the gastric mucosa. Macromolecular leakage of FITC-BSA, vessel diameters and leucocyte activity were quantified using image analysis. RESULTS: Pretreatment with ketotifen or pyrilamine, followed by ethanol, caused no change in macromolecular leakage compared with controls. Both compounds prevented blood flow stasis in all areas and no lesion formation was observed. However, increased leucocyte activity and increases in vessel diameter were observed following pretreatment with ketotifen and pyrilamine, respectively. CONCLUSIONS: The data suggest that vasoactive substances released from mast cells may be involved in the aetiology of ethanol-induced gastric mucosal damage. The prevention of these normal physiological responses to injury may lead to the employment of other microcirculatory mechanisms of defence.  相似文献   
50.
OBJECTIVE: Percutaneous endoscopic gastrostomy (PEG) feeding has been validated in specific clinical situations such as acute stroke with dysphagia and oropharyngeal malignancy. The perception that gastrostomy insertion is safe and technically simple has led to an increase in the demands for PEG insertion, encompassing clinical applications such as in patients with dementia, in whom its role has not been justified. The purpose of this study was to compare the mortality of patients with dementia who were fed by PEG to that of other subgroups of patients requiring gastrostomy feeding. METHODS: The study focused on a cohort of 361 consecutive patients requiring PEG feeding between August 1992 and July 1997 from two District General Hospitals (Rotherham District General Hospital and Doncaster Royal Infirmary) in South Yorkshire. A retrospective cohort survival analysis was performed using the Kaplan-Meier survival method and Cox proportional hazards analysis. RESULTS: In all patients requiring gastrostomy feeding there is a high initial mortality of 28% at 30 days. However, patients with dementia have a worse prognosis compared to other subgroups, with 54% having died at 1 month and 90% at 1 yr (log rank test p < 0.0001). This difference remained significant (log rank p < 0.0001) after adjusting for age at the time of PEG insertion. CONCLUSIONS: This is the first demonstration in the United Kingdom that the mortality of patients with dementia who are fed by gastrostomy is considerable. Consequently, we may wish to advise against gastrostomy feeding in selected patients within this clinical setting.  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