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   5966篇
  免费   329篇
  国内免费   33篇
耳鼻咽喉   33篇
儿科学   194篇
妇产科学   124篇
基础医学   791篇
口腔科学   140篇
临床医学   431篇
内科学   1278篇
皮肤病学   99篇
神经病学   428篇
特种医学   279篇
外科学   716篇
综合类   24篇
预防医学   622篇
眼科学   292篇
药学   438篇
中国医学   7篇
肿瘤学   432篇
  2023年   28篇
  2022年   73篇
  2021年   130篇
  2020年   70篇
  2019年   108篇
  2018年   122篇
  2017年   115篇
  2016年   99篇
  2015年   130篇
  2014年   151篇
  2013年   180篇
  2012年   337篇
  2011年   339篇
  2010年   177篇
  2009年   156篇
  2008年   306篇
  2007年   312篇
  2006年   339篇
  2005年   330篇
  2004年   341篇
  2003年   304篇
  2002年   306篇
  2001年   213篇
  2000年   184篇
  1999年   163篇
  1998年   67篇
  1997年   57篇
  1996年   74篇
  1995年   40篇
  1994年   36篇
  1993年   23篇
  1992年   93篇
  1991年   78篇
  1990年   74篇
  1989年   81篇
  1988年   91篇
  1987年   60篇
  1986年   60篇
  1985年   57篇
  1984年   54篇
  1983年   32篇
  1981年   17篇
  1979年   25篇
  1978年   30篇
  1976年   21篇
  1975年   21篇
  1974年   23篇
  1973年   34篇
  1972年   18篇
  1968年   18篇
排序方式: 共有6328条查询结果,搜索用时 15 毫秒
81.
PURPOSE Early-stage colon cancer patients (Dukes A or B; pT1–T3 pNO pMO) are excluded from adjuvant chemotherapy following potentially curative surgery because they are expected to have good long-term survival. However, 20 percent to 30 percent of these patients ultimately succumb from recurrent disease. This indicates that the conventional staging procedures may be unable to precisely predict cancer prognosis.METHODS In 65 early-stage colon cancers, we investigated by immunohistochemistry the role of molecular markers such as p27, p53, and vascular endothelial growth factor in identifying high-risk patients who may benefit from adjuvant treatments.RESULTS No clinicopathologic factor, namely Dukes stage, t parameter, number of resected nodes, and vascular or lymphatic invasion, was found be an independent significant predictor of disease-specific and disease-free survival. In contrast, each molecular marker predicted survival and recurrence rates much better than the conventional Dukes staging system. The best combination of variables for prediction of long-term outcome and recurrence rate included p27, p53, and vascular endothelial growth factor. Interestingly, the greater the number of molecular alterations, the lower the five-year estimated survival function. Nearly all cancer-related deaths were observed among patients whose colon cancers expressed all three molecular alterations. Regardless of Dukes stage, the recurrence rate was found to increase with the increase in the number of molecular alterations. Early-stage colon cancers expressing p27 down-regulation and high p53 and vascular endothelial growth factor immunoreactivity showed a 100 percent actuarial four-year recurrence rate.CONCLUSIONS Assessment of molecular alterations may be useful to identify a higher-risk group of early-stage colon cancer patients who may benefit from adjuvant chemotherapy.  相似文献   
82.
83.
84.
BACKGROUND: The pathogenesis of alcoholic pancreatitis may involve the metabolism of ethanol (via oxidative and non-oxidative pathways) within the pancreas. The aims of this study were to determine the rate of non-oxidative metabolism in isolated rat pancreatic acini and to compare this to the rate of ethanol oxidation. METHODS: Pancreatic acini were isolated from male Sprague-Dawley rats and incubated with (14)C-ethanol. Radiolabelled fatty acid ethyl esters (non-oxidative metabolites) were isolated from lipid extracts by thin-layer chromatography. Radiolabelled acetate (oxidative metabolite) was isolated from the incubation medium by ion-exchange chromatography. RESULTS: Non-oxidative metabolism by isolated pancreatic acini was demonstrated. At 50 and 100 mmol/l ethanol, fatty acid ethyl ester concentrations were 49.6 +/- 13.3 and 199 +/- 93 micromol/l, respectively. These levels have previously been shown to result in tissue injury. Non-oxidative metabolism was increased 9-fold by addition of oleic acid and inhibited by the lipase inhibitor, tetrahydrolipstatin, by 91.05 +/- 1.99%. The rate of oxidative metabolism was 21-fold higher than that of non-oxidative metabolism. CONCLUSIONS: Intact pancreatic cells metabolize ethanol by the non-oxidative pathway, generating fatty acid ethyl esters at a rate sufficient to cause pancreatic damage. Oxidative metabolism of ethanol occurs at a much higher rate and may also play a role in pancreatitis.  相似文献   
85.
Time- and dose-dependent changes in plasma catecholamines, heart rate, and blood pressure were studied in response to sublethal doses of intravenous (i.v.) bacterial endotoxin in conscious male rats. Hypotension occurred with high endotoxin (1,000 micrograms/kg), whereas hypertension occurred in the low-dose group (10 micrograms/kg). All groups had significant tachycardia, which was dose and time dependent, but heart rate was unchanged for the first 2 hr in the low-dose groups (100 and 10 micrograms/kg). Plasma levels of norepinephrine (NE) and epinephrine (E) increased with both dose and time and there was significant interaction of dose and time effects. NE levels increased maximally at 0.5 hr following the highest dose of endotoxin and remained elevated during the protocol. Plasma E levels were maximal at 0.5 hr in the high-dose group, but then declined while remaining significantly higher than the 10 and 100 micrograms/kg endotoxin-treated groups for the duration of the protocol. Peak E levels in the 100 and 10 micrograms/kg group occurred at 3.0 hr and then decreased at the 6.0 hr time. Significant increases in plasma catecholamines and heart rate with endotoxin in the absence of significant hypotension present the possibility that factors other than blood pressure may be mediating efferent sympathetic outflow in endotoxicosis.  相似文献   
86.
87.
The use of thumbtacks in massive presacral bleeding   总被引:4,自引:0,他引:4  
  相似文献   
88.
BACKGROUND/AIMS: Helicobacter pylori (H. pylori) infection is one of the most common gastrointestinal diseases. An increasing number of people undergo different treatment options. Unfortunately, H. pylori therapy may be troublesome for drug side effects and inefficacious for resistance to antibiotics. METHODOLOGY: One hundred and ninety-three (193) H. pylori-positive patients were randomly assigned to one of the following 7-day treatments: Group A (N = 64): amoxicillin, clarithromycin and rabeprazole; Group B (N = 64): tinidazole, clarithromycin and ranitidine bismuth citrate; Group C (N = 65): tinidazole, clarithromycin and rabeprazole Eradication was assessed by 13C-Urea Breath Test 6-8 weeks after the end of the therapy. Not-eradicated patients underwent a second cycle with tinidazole, tetracycline, bismuth and rabeprazole. All patients were asked to complete a validated questionnaire regarding presence and intensity of drug side effects. RESULTS: One hundred and eighty-eight out of the 193 H. pylori-positive patients (96%) completed therapy. No significant difference in eradication rates was observed among the three groups both in intention to treat analysis and in per protocol analysis. No significant difference in incidence of side effects occurred among groups after the first-line regimens: 48% in group A, 44% in group B and 46% in group C. Twenty-two out of the 193 enrolled subjects (11%) were not eradicated after the first-line therapy. Among them, 86% were successfully eradicated by the tinidazole, tetracycline, bismuth and rabeprazole therapy. Moreover, during quadruple therapy, a higher prevalence and intensity of side effects than in each one of the groups submitted to the first-line triple therapy was observed. CONCLUSIONS: This study shows that triple rabeprazole-based eradicating regimens are effective and safe. Incidence of side effects seems low and similar in different three-drug regimens used. Quadruple therapy, which appear highly efficacious as a second line therapy, is associated with a significantly higher incidence of side effects when compared to first-line treatment.  相似文献   
89.
Urinary incontinence is a common problem in older subjects, very often wrongfully accepted as a normal part of the aging process. A total of 520 subjects (208 males and 312 females; mean age 74.8 +/- 11.8 years), from both private- and nursing-home dwelling populations, were included in this study aimed to estimate the incidence of urinary incontinence and identify factors associated with condition, in aged subjects. The incidence and type of urinary incontinence (stress, urge or mixed incontinence) were assessed by structured questionnaires and diagnosis was confirmed by a seven-day consecutive voiding diary. Assessment of physical, cognitive and emotional functions was performed on each subject using the Mini Mental State Examination (MMSE), Instrumental Activities of Daily Living Scale (IADL), Tinetti Scale (gait), Tinetti Scale (balance) and Geriatric Depression Scale (GDS) instruments. In the total population sample the incidence of urinary incontinence was 47.9%. The incontinence cases were classified, according to the different types, as: stress incontinence (males: 3.4%; females: 8.7%; males+females: 6.5%); urge incontinence (males: 27.4%; females: 31.4%; males+females: 29.8%); mixed incontinence (males: 20.2%; females: 5.8%; males+females: 11.5%). In the total population sample, no significant relationship was found between age and prevalence of urinary incontinence. In the elderly female group, age significantly correlated in a direct manner with urge incontinence (P<0.01) and inversely with stress incontinence (P<0.001). Only in the male sex group age significantly correlated with mixed incontinence (P<0.005). Multiple linear regression analysis showed that the dependent variable 'incontinence' could be predicted by MMSE (P<0.001) in the male sex group and by the Tinetti Scale (gait) (P<0.001) in the female sex group.  相似文献   
90.
BACKGROUND/AIMS: The outcome of endoscopic biliary stent insertion for postoperative bile duct stenosis was retrospectively evaluated. METHODOLOGY: Fifty-seven patients with biliary stenosis from laparoscopic cholecystectomy were included from February 1992 to January 2000. One to three stents were inserted for an average of 12.4 months, with stent exchange every 3 months to avoid cholangitis caused by clogging. RESULTS: Successful stent insertion was achieved in 43/57 (75.4%) patients. Stent insertion failed in 10 patients with complete and in 4 patients with incomplete biliary obstruction. Early complications occurred in 4 patients. Late complications occurred in 5/43 patients. Five patients experienced recurrence of stenosis. CONCLUSIONS: Endoscopic treatment should be the initial management of choice for postoperative bile duct stenosis.  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