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   1798篇
  免费   118篇
  国内免费   8篇
耳鼻咽喉   11篇
儿科学   29篇
妇产科学   17篇
基础医学   164篇
口腔科学   27篇
临床医学   139篇
内科学   562篇
皮肤病学   15篇
神经病学   145篇
特种医学   43篇
外科学   298篇
综合类   43篇
一般理论   2篇
预防医学   170篇
眼科学   47篇
药学   64篇
中国医学   2篇
肿瘤学   146篇
  2022年   17篇
  2021年   29篇
  2020年   27篇
  2019年   35篇
  2018年   36篇
  2017年   28篇
  2016年   38篇
  2015年   41篇
  2014年   49篇
  2013年   82篇
  2012年   96篇
  2011年   102篇
  2010年   50篇
  2009年   50篇
  2008年   116篇
  2007年   101篇
  2006年   102篇
  2005年   98篇
  2004年   80篇
  2003年   96篇
  2002年   103篇
  2001年   44篇
  2000年   40篇
  1999年   39篇
  1998年   14篇
  1997年   18篇
  1996年   17篇
  1995年   18篇
  1994年   13篇
  1993年   11篇
  1992年   21篇
  1991年   12篇
  1990年   20篇
  1989年   17篇
  1988年   18篇
  1987年   13篇
  1986年   23篇
  1985年   18篇
  1984年   15篇
  1983年   16篇
  1982年   13篇
  1981年   14篇
  1980年   6篇
  1979年   8篇
  1978年   7篇
  1976年   6篇
  1974年   10篇
  1972年   8篇
  1969年   6篇
  1968年   13篇
排序方式: 共有1924条查询结果,搜索用时 281 毫秒
31.
32.
Helicobacter pylori and the prevention of gastric cancer.   总被引:2,自引:0,他引:2  
BACKGROUND: Helicobacter pylori is an important cause of stomach cancer that infects a substantial proportion of the Canadian adult population. H pylori can be detected by noninvasive tests and effectively eradicated by medical treatment. Screening for and treatment of H pylori may represent a significant opportunity for preventive oncology. METHODS: Cancer Care Ontario organized a workshop held in Toronto, Ontario, on October 24 and 25, 2002, to: review the current state of knowledge regarding H pylori treatment and cancer prevention; determine if there is currently sufficient evidence to consider the promotion of H pylori treatment for the purpose of cancer prevention; identify critical areas for research; and advise Cancer Care Ontario on H pylori and cancer prevention. RESULTS: Workshop participants developed a number of recommendations for research into the relationship between H pylori and stomach cancer, including determining the prevalence of infection in different regions of Canada, the pathogenetic sequence of carcinogenesis from H pylori infection, and the implementation of a prospective observational study. INTERPRETATION: Although the rate of H pylori infection is declining in Canada and the treatment of H pylori is generally accepted to be safe, the evidence to date may not warrant the implementation of population screening for H pylori infection to prevent gastric carcinoma in average-risk populations. Rather, a demonstration project is needed to estimate prevalence, evaluate the merits of screening, measure patient compliance and physician participation, develop education materials, establish a registry for monitoring and evaluation, and develop a quality assurance framework.  相似文献   
33.
34.
BACKGROUND: Highly active antiretroviral therapy (HAART) including two nucleoside analogues and a potent protease inhibitor is standard of care initial therapy for HIV-infected adults. The best-tolerated and most potent initial HAART regimen is unknown and was investigated in this study. METHODS: One hundred and nine HIV-infected adults with no prior antiretroviral therapy, and CD4 lymphocyte counts < 500 x 10(6) cells/l or plasma HIV RNA > 30,000 copies/ml were randomized to zidovudine-lamivudine-indinavir (ZDV-3TC-IDV), stavudine-lamivudine-indinavir (d4T-3TC-IDV) or stavudine-didanosine-indinavir (d4T-ddI-IDV) for 52 weeks. The primary endpoints were plasma HIV RNA and drug-related adverse events. Other assessments were overall safety, adherence and adverse events, CD4 lymphocyte counts, cutaneous delayed type hypersensitivity (DTH) responses and quality of life (Euroqol). RESULTS: Only 58% patients had HIV RNA < 50 copies/ml plasma at 12 months, with no significant difference between the three regimes (P = 0.34). Drug-related adverse events sufficiently severe to warrant drug discontinuation were less common (P = 0.06) in patients receiving d4T-3TC-IDV (18%) than in those receiving ZDV-3TC-IDV (34%) or d4T-ddI-IDV (41%). The percentages of patients who remained on their assigned therapy with plasma HIV RNA < 50 copies/ml at 52 weeks were 60% with d4T-3TC-IDV, 53% with ZDV-3TC-IDV and 35% with d4T-ddI-IDV. Virological failure at 52 weeks was more likely in those whose adherence was estimated to be < 100% in the first 4 weeks of therapy (P = 0.02), but not in those who developed grade 3 or 4 drug-related adverse events. At 52 weeks, the mean CD4 lymphocyte count increase was 200 x 10(6) cells/l with only 7% of patients having counts lower than at baseline; DTH responses improved but remained clinically impaired in most patients. Quality of life improved significantly in all groups. CONCLUSIONS: Initial HAART regimens including IDV failed to suppress plasma HIV RNA to < 50 copies/ml in > 40% patients after only 12 months of therapy although there was significant overall improvement immunologically and in quality of life. The type of dual nucleoside combination used was less important in predicting virological failure than was imperfect adherence early in therapy. Consideration should be given to modifying a HAART regimen relatively early in non-adherent patients.  相似文献   
35.
BACKGROUND: Methotrexate has become a standard second-line agent for the treatment of sarcoidosis. Because sarcoidosis has a high frequency of liver involvement, we routinely perform a liver biopsy after each cumulative gram of methotrexate therapy in patients with sarcoidosis in whom we plan to continue therapy. METHODS: Following a previously described protocol for methotrexate therapy, we have performed 100 liver biopsies on 68 patients with chronic sarcoidosis at our institution. On the basis of the liver biopsy results, we identified the following 4 groups: sarcoidosis (47 cases), toxic effects of methotrexate (14 cases), hepatitis C (2 cases), and normal liver tissue (37 cases). RESULTS: We found no difference among the groups in terms of age, weight at time of biopsy, the number of patients receiving corticosteroids at the time of biopsy, cumulative dose of methotrexate, race, or sex. The 14 cases of toxic reactions to methotrexate included 5 patients who had undergone 1 or more previous liver biopsies in which the results did not show toxic effects. We found a significant difference between groups for levels of alkaline phosphatase and asparate aminotransferase at the time of starting (or restarting) methotrexate therapy (analysis of variance, P<.05). This finding was also true for the liver function tests performed at the time of the biopsy (analysis of variance, P<.05). The highest values were for those whose biopsy findings showed sarcoidosis. CONCLUSIONS: Toxic reactions to methotrexate eventually occurred in more than 10% of patients with sarcoidosis treated for more than 2 years with methotrexate. Because of hepatic involvement owing to sarcoidosis, results of serial liver function tests were not useful in determining which patients would have this reaction to methotrexate.  相似文献   
36.
OBJECTIVE: To document disease activity and functional status in patients with scleroderma (systemic sclerosis [SSc]) and Raynaud's phenomenon (RP) and to determine the sensitivity to change, reliability, ease of use, and validity of various outcome measures in these patients. METHODS: Patients with SSc and moderate-to-severe RP participating in a multicenter RP treatment trial completed daily diaries documenting the frequency and duration of RP attacks and recorded a daily Raynaud's Condition Score (RCS). Mean scores for the 2-week periods prior to baseline (week 0), end of trial (week 6), and posttrial followup (week 12) were calculated. At weeks 0, 6, and 12, physicians completed 3 global assessment scales and performed clinical assessments of digital ulcers and infarcts; patients completed the Health Assessment Questionnaire (HAQ), the Arthritis Impact Measurement Scales 2 (AIMS2) mood and tension subscales, 5 specific SSc/RP-related visual analog scales (VAS), and 3 other VAS global assessments. We used these measures to document baseline disease activity and to assess their construct validity, sensitivity to change, and reliability in trial data. RESULTS: Two hundred eighty-one patients (248 women, 33 men; mean age 50.4 years [range 18-82 years]) from 14 centers participated. Forty-eight percent had limited cutaneous SSc; 52% had diffuse cutaneous SSc. Fifty-nine patients (21%) had digital ulcers at baseline. Patients had 3.89 +/- 2.33 (mean +/- SD) daily RP attacks (range 0.8-14.6), with a duration of 82.1 +/- 91.6 minutes/attack. RCS for RP activity (possible range 0-10) was 4.30 +/- 1.92. HAQ scores (0-3 scale) indicated substantial disability at baseline (total disability 0.86, pain 1.19), especially among the subscales pertaining to hand function (grip, eating, dressing). AIMS2 mood and tension scores were fairly high, as were many of the VAS scores. Patients with digital ulcers had worse RCS, pain, HAQ disability (overall, grip, eating, and dressing), physician's global assessment, and tension, but no significant difference in the frequency of RP, duration of RP, patient's global assessment, or mood, compared with patients without digital ulcers. VAS scores for digital ulcers as rated by the patients were not consistent with the physician's ratings. Factor analysis of the 18 measures showed strong associations among variables in 4 distinct domains: disease activity, RP measures, digital ulcer measures, and mood/tension. Reliability of the RCS, HAQ pain and disability scales, and AIMS2 mood and tension subscales was high. The RP measures demonstrated good sensitivity to change (effect sizes 0.33-0.76). CONCLUSION: Our findings demonstrate that the significant activity, disability, pain, and psychological impact of RP and digital ulcers in SSc can be measured by a small set of valid and reliable outcome measures. These outcome measures provide information beyond the quantitative metrics of RP attacks. We propose a core set of measures for use in clinical trials of RP in SSc patients that includes the RCS, patient and physician VAS ratings of RP activity, a digital ulcer/infarct measure, measures of disability and pain (HAQ), and measures of psychological function (AIMS2).  相似文献   
37.
ObjectivesMobile stroke unit (MSU) has been shown to rapidly provide pre-hospital thrombolysis in acute ischemic stroke (AIS). MSU encounters neurological disorders other than AIS that require emergent treatment.Methods/MaterialsWe obtained pre-hospital diagnosis and treatment data from the prospectively collected dataset on 221 consecutive MSU encounters. Based on initial clinical evaluation and neuroimaging obtained on MSU, the diagnosis of AIS (definite, probable, and possible AIS, transient ischemic attack), intracranial hemorrhage, and likely stroke mimics was made.ResultsFrom July 2014 to April 2015, 221 patients were treated on MSU. 78 (35%) patients had initial clinical diagnosis of definite/probable AIS or TIA, 69 (31%) were diagnosed as possible AIS or TIA, 15 (7%) had intracranial hemorrhage while 59 patients (27%) were diagnosed as likely stroke mimics. Stroke mimics encountered included 13 (6%) metabolic encephalopathy, 11 (5%) seizures, 9 (4%) migraines, 3 (1%) substance abuse, 2 (1%) CNS tumor, 3 (1%) infectious etiology and 3 (1%) hypoglycemia. Fifty-four (24%) patients received non-thrombolytic treatments on MSUConclusionAbout one third of MSU encounters were not AIS initially, including intracranial hemorrhage and stroke mimics. MSU can be utilized to provide pre-hospital treatments in emergent neurological conditions other than AIS.  相似文献   
38.
39.
40.
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