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   5891篇
  免费   547篇
  国内免费   30篇
耳鼻咽喉   23篇
儿科学   172篇
妇产科学   93篇
基础医学   937篇
口腔科学   93篇
临床医学   661篇
内科学   1358篇
皮肤病学   249篇
神经病学   523篇
特种医学   328篇
外科学   547篇
综合类   101篇
一般理论   2篇
预防医学   654篇
眼科学   57篇
药学   350篇
  1篇
中国医学   3篇
肿瘤学   316篇
  2023年   34篇
  2021年   67篇
  2020年   63篇
  2019年   71篇
  2018年   102篇
  2017年   76篇
  2016年   106篇
  2015年   123篇
  2014年   139篇
  2013年   213篇
  2012年   325篇
  2011年   343篇
  2010年   191篇
  2009年   174篇
  2008年   287篇
  2007年   272篇
  2006年   256篇
  2005年   249篇
  2004年   247篇
  2003年   226篇
  2002年   230篇
  2001年   206篇
  2000年   149篇
  1999年   178篇
  1998年   159篇
  1997年   112篇
  1996年   105篇
  1995年   103篇
  1994年   81篇
  1993年   78篇
  1992年   96篇
  1991年   97篇
  1990年   86篇
  1989年   133篇
  1988年   108篇
  1987年   95篇
  1986年   83篇
  1985年   74篇
  1984年   51篇
  1983年   52篇
  1982年   37篇
  1981年   33篇
  1979年   48篇
  1978年   40篇
  1977年   38篇
  1976年   37篇
  1975年   32篇
  1973年   34篇
  1972年   31篇
  1971年   37篇
排序方式: 共有6468条查询结果,搜索用时 11 毫秒
61.
62.
BACKGROUND: Many dual and triple therapy treatment regimens have been proposed for the eradication of Helicobacter pylori. However, assessing the relative efficacy of these regimens is complicated by differences in study design, and few well-controlled comparative studies have been reported. METHODS: This multicentre, randomized, double-blind study involved 530 duodenal ulcer patients, of whom 520 had confirmed H. pylori infection. Patients received 14 days b.d. dual therapy of either ranitidine bismuth citrate (RBC) 400 mg or omeprazole 20 mg, both with clarithromycin 500 mg to eradicate H. pylori, followed by a further 14 days of treatment with RBC 400 mg b. d. or omeprazole 20 mg o.d. to facilitate ulcer healing. H. pylori eradication and ulcer healing were assessed at least 26 days after the end of treatment. Adverse events were recorded throughout the study. RESULTS: H. pylori was eradicated in 90% of patients who received RBC with clarithromycin and in 66% of patients who received omeprazole with clarithromycin (per protocol; P<0.001). intention-to-treat eradication rates were 77% and 60%, respectively (P<0.001). Ulcer healing rates were 97% in the RBC treatment group and 95% in the omeprazole treatment group. Only 3% and 1% of patients in the RBC and omeprazole treatment groups, respectively, were withdrawn due to adverse events. CONCLUSIONS: RBC with clarithromycin is a simple and highly effective dual therapy regimen for the eradication of H. pylori, and is significantly more effective than omeprazole with clarithromycin. Both treatment regimens are well tolerated and effectively heal duodenal ulcers.  相似文献   
63.
64.
Delayed evolution of posttraumatic subdural hygroma   总被引:1,自引:0,他引:1  
Five hundred and forty-six patients in a consecutive series of 1,601 patients with craniocerebral trauma had computed tomography. One hundred and ninety-six patients had a follow-up CT scan. Thirteen patients (6.6%) developed apparently "silent" subdural hygromas of delayed evolution noted from six to 46 days after injury (average 22 days). Three of 10 patients (30%) improved after operation. No patient with a severe cerebral deficit (decortication or decerebration) improved. The three unoperated hygromas and the six that persisted after operation tended to resolve spontaneously. The infrequent and modest improvement following surgical treatment and the tendency to spontaneous resolution suggest that operation may be unnecessary in many patients with posttraumatic subdural hygroma of delayed evolution.  相似文献   
65.
66.
Objectives: To describe the physical growth patterns of infants born to narcotic dependent mothers (INDM) over a 12 months period and, if possible, to relate the growth to drug taking patterns during pregnancy.
Methodology: The growth of a cohort of 43 INDM was measured during the first 12 months of life. Weight and length measurements were compared with percentile charts and converted to Z scores. Questionnaire data about drug taking practices, demographic variables and the neonatal period (including withdrawal scores) were obtained.
Results: Twenty-four (55.8%) of INDM had evidence of neonatal drug withdrawal requiring treatment with phenobarbitone. At birth, Z scores for weight and length indicated relative intrauterine growth retardation. By 12 months, there had been some catch up growth, but Z scores for weight and length were still below zero. Persistent weight retardation at 12 months was correlated with methadone dosage during pregnancy, but not the need for phenobarbitone therapy.
Conclusions: The growth patterns of INDM in the first 12 months of life indicated that at birth there was evidence of intrauterine growth retardation, but by 12 months the growth was little different from the rest of the community. There appears to be some influence of narcotic agents taken while pregnant on subsequent growth of INDM.  相似文献   
67.
68.
Aflatoxin B1 (AFB1), a mutagen and hepatocarcinogen in rats and humans, is a contaminant of the human food supply, particularly in parts of Africa and Asia. AFB1-induced changes in gene expression may play a part in the development of the toxic, immunosuppressive and carcinogenic properties of this fungal metabolite. An understanding of the-role of AFB1 in modulating gene regulation should provide insight regarding mechanisms of AFB1-induced carcinogenesis. We used three PCR- based subtractive techniques to identify AFB1-responsive genes in cultured primary rat hepatocyte RNA: differential display PCR (DD-PCR), representational difference analysis (RDA) and suppression subtractive hybridization (SSH). Each of the three techniques identified AFB1- responsive genes, although no individual cDNA was isolated by more than one technique. Nine cDNAs isolated using DD-PCR, RDA or SSH were found to represent eight genes that are differentially expressed as a result of AFB1 exposure. Genes whose mRNA levels were increased in cultured primary rat hepatocytes after AFB1 treatment were corticosteroid binding globulin (CBG), cytochrome P450 4F1 (CYP4F1), alpha-2 microglobulin, C4b-binding protein (C4BP), serum amyloid A-2 and glutathione S-transferase Yb2 (GST). Transferrin and a small CYP3A-like cDNA had reduced mRNA levels after AFB1 exposure. Full-length CYP3A mRNA levels were increased. When liver RNA from AFB1-treated male F344 rats was evaluated for transferrin, CBG, GST, CYP3A and CYP4F1 expression, a decrease in transferrin mRNA and an increase in CBG, GST, CYP3A and CYP4F1 mRNA levels was also seen. Analysis of the potential function of these genes in maintaining cellular homeostasis suggests that their differential expression could contribute to the toxicity associated with AFB1 exposure.   相似文献   
69.
Postoperative intra-abdominal adhesions are associated with significant morbidity and mortality. In this study, the effect of topical fibrin glue (FG) on adhesion formation in a rat model was investigated. Forty Sprague-Dawley male rats underwent midline laparotomy. Bilateral peritoneal-muscular abdominal wall defects were created and then replaced with premeasured soft tissue Goretex patches. Rats were randomized to FG sprayed over the patches or to a control group. Two observers blinded to the randomization assessed the severity of adhesions to the patch by scoring the density of adhesions (grades 0-3) and the percentage of the patch area covered by adhesions (0-100%). The mean percentage of the patch covered by adhesions was 32.8 +/- 6.1 per cent for the FG group versus 57.9 +/- 6.7 per cent for the control group (P < 0.01). The mean density of adhesions for the FG group was 0.95 (+/-0.17) versus 2.0 (+/-0.21) for the control group (P = 0.001). Topical FG reduces the severity and density of intra-abdominal adhesions in a rat model.  相似文献   
70.
Neill F  Sear JW  French G  Lam H  Kemp M  Hooper RJ  Foex P 《Anaesthesia》2000,55(7):641-647
We investigated the use of measurements of serum concentrations of the cardiac proteins troponins I and T as biochemical markers of myocardial cell damage in 80 patients undergoing vascular or major orthopaedic surgery. Holter electrocardiographic monitoring was carried out before surgery and for 3 days after surgery. Blood samples for troponins I and T and creatine kinase-MB isoenzyme were taken on each of these 4 days. Outcome was assessed at 3 months using a patient questionnaire, general practitioner follow-up and case notes review. Silent postoperative myocardial ischaemia was detected in 21 patients; increases in troponins I and T and creatine kinase-MB occurred in four, six and 17 of these patients, respectively. Eight patients suffered major postoperative complications (cardiac death, myocardial ischaemia, congestive cardiac failure, unstable angina and cerebrovascular accident) and 21 minor complications (poorly controlled hypertension needing increased or new additional treatment, palpitations, increased tiredness or shortness of breath in the absence of known respiratory disease). There were no associations between postoperative ischaemia and cardiac protein concentrations. The relative odds for the associations of major adverse outcome at 3 months after surgery and postoperative ischaemia or increased serum concentrations of the three proteins were 5.39 [95% confidence intervals 1.16-27.67] for postoperative ischaemia; 5.64 [1.07-31.00] for creatine kinase-MB isoenzyme; 17.00 [2.20-116.54] for troponin T and 13.20 [1.12-135.00] for troponin I. We found troponin T to be the only prospective marker for both major and minor cardiovascular complications (relative odds 10.65 [1.26-252.88]).  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