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   2920篇
  免费   159篇
  国内免费   11篇
耳鼻咽喉   34篇
儿科学   78篇
妇产科学   54篇
基础医学   499篇
口腔科学   84篇
临床医学   254篇
内科学   523篇
皮肤病学   52篇
神经病学   334篇
特种医学   79篇
外科学   373篇
综合类   13篇
预防医学   264篇
眼科学   27篇
药学   268篇
中国医学   3篇
肿瘤学   151篇
  2022年   25篇
  2021年   45篇
  2020年   21篇
  2019年   28篇
  2018年   50篇
  2017年   29篇
  2016年   38篇
  2015年   35篇
  2014年   68篇
  2013年   102篇
  2012年   139篇
  2011年   158篇
  2010年   87篇
  2009年   89篇
  2008年   150篇
  2007年   161篇
  2006年   156篇
  2005年   175篇
  2004年   149篇
  2003年   151篇
  2002年   155篇
  2001年   37篇
  2000年   22篇
  1999年   33篇
  1998年   67篇
  1997年   60篇
  1996年   42篇
  1995年   45篇
  1994年   38篇
  1993年   40篇
  1992年   37篇
  1991年   32篇
  1990年   25篇
  1989年   26篇
  1988年   26篇
  1987年   31篇
  1986年   37篇
  1985年   41篇
  1984年   51篇
  1983年   28篇
  1982年   47篇
  1981年   30篇
  1980年   26篇
  1979年   24篇
  1978年   26篇
  1977年   17篇
  1975年   36篇
  1974年   13篇
  1973年   14篇
  1967年   13篇
排序方式: 共有3090条查询结果,搜索用时 31 毫秒
61.
We performed two case–control studies on brain tumours diagnosed during 1 January 1997 to 30 June 2000 and 1 July 2000 to 31 December 2003, respectively. Living cases and controls aged 20–80 years were included. An additional study was performed on deceased cases with a malignant brain tumour using deceased controls. Pooled results for glioma yielded for ipsilateral use of mobile phone odds ratio (OR) = 2.9, 95% confidence interval (CI) = 1.8–4.7 in the >10 years latency group. The corresponding result for cordless phone was OR = 3.8, 95% CI = 1.8–8.1. OR increased statistically significant for cumulative use of wireless phones per 100 h and per year of latency. For high-grade glioma ipsilateral use of mobile phone gave OR = 3.9, 95% CI = 2.3–6.6 and cordless phone OR = 5.5, 95% CI = 2.3–13 in the >10 years latency group. Heredity for brain tumour gave OR = 3.4, 95% CI = 2.1–5.5 for glioma. There was no interaction with use of wireless phones. X-ray investigation of the head gave overall OR = 1.3, 95% CI = 1.1–1.7 for glioma without interaction with use of wireless phones or heredity. In conclusion use of mobile and cordless phone increased the risk for glioma with highest OR for ipsilateral use, latency >10 years and third tertile of cumulative use in hours. In total, the risk was highest in the age group <20 years for first use of a wireless phone.  相似文献   
62.
63.
The present study examines non-coercive interview techniques aimed for eliciting intelligence from human sources. Two versions of the Scharff technique were compared against the direct approach (a combination of open-ended and specific questions). The Scharff conditions were conceptualised into four tactics and differed with respect to when the confirmation tactic was implemented: before or after an initial open-ended question. Participants (n = 93) took the role of a source in a phone interview and were instructed to strike a balance between not revealing too little or too much information. In general, the Scharff technique outperformed the direct approach on all important measures. The sources in the Scharff conditions revealed more new information, and found it more difficult to understand the interviewer's information objectives. Importantly, the sources interviewed by the Scharff technique underestimated how much new information they revealed, whereas the sources interviewed by the direct approach overestimated the amount of new information revealed. Although no clear order effects of the Scharff tactics were found, we introduce an alternative method for implementing the confirmation tactic.  相似文献   
64.
Various modeling methods have been proposed to estimate the potential predictive ability of polygenic risk variants that predispose to various common diseases. However, it is unknown whether differences between them affect their conclusions on predictive ability. We reviewed input parameters, assumptions and output of the five most common methods and compared their estimates of the area under the receiver operating characteristic (ROC) curve (AUC) using hypothetical data representing effect sizes and frequencies of genetic variants, population disease risk and number of variants. To assess the accuracy of the estimated AUCs, we aimed to reproduce the AUCs of published empirical studies. All methods assumed that the combined effect of genetic variants on disease risk followed a multiplicative risk model of independent genetic effects, but they either assumed per allele, per genotype or dominant/recessive effects for the genetic variants. Modeling strategy and input parameters differed. Methods used simulation analysis or analytical formulas with effect sizes quantified by odds ratios (ORs) or relative risks. Estimated AUC values were similar for lower ORs (<1.2). When AUCs were larger (>0.7) due to variants with strong effects, differences in estimated AUCs between methods increased. The simulation methods accurately reproduced the AUC values of empirical studies, but the analytical methods did not. We conclude that despite differences in input parameters, the modeling methods estimate similar AUC for realistic values of the ORs. When one or more variants have stronger effects and AUC values are higher, the simulation methods tend to be more accurate.  相似文献   
65.

Objective

To introduce a novel, simple, utility‐based outcome measure, the number needed per quality‐adjusted life year (QALY) gained (NNQ), and to apply it in clinical practice in anti–tumor necrosis factor (anti‐TNF)–treated patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA), and spondylarthritis (SpA).

Methods

The NNQ is the number of patients one has to treat in order to gain 1 QALY. It is calculated as the inverted value of the utility gain (area under the curve) over 1 year in a cohort subjected to an intervention. EuroQol Index utility data from the South Swedish Arthritis Treatment register were used.

Results

Patients with RA (n = 1,001), PsA (n = 241), and SpA (n = 255) were eligible for the study. First, second, and third treatment courses were studied. For RA, NNQ was 4.5, 6.4, and 5.2 for first, second, and third courses, respectively. For PsA and SpA, NNQ was 4.2–4.5, irrespective of treatment order. Treatment groups with <50 patients were not analyzed. During the study period 2002–2007, there were no secular trends of utility gains.

Conclusion

The NNQ is an easily derived and understandable utility‐based outcome measure that may be useful for stakeholders and decision makers as well as for clinicians. It was readily applied in this study of TNF blockade across 3 arthritis diagnoses. NNQ varied little over diagnoses and treatment course order, with a possible exception in second treatment course in RA.  相似文献   
66.
67.
68.
Surgery for fulminating colitis during pregnancy   总被引:2,自引:1,他引:2  
Two cases of fulminating colitis presenting during pregnancy are described. In both cases, resectional surgery was performed. In the first case, cesarean section was combined with subtotal colectomy and ileostomy during the 32nd week of gestation. In the second case, cesarean section was performed during the 33rd week of gestation and proctocolectomy in the puerperium. In both cases, histopathologic examination showed colitis more consistent with Crohn's disease. It is concluded that if fulminating colitis appears during pregnancy it should be treated in the same manner as in the nonpregnant state.  相似文献   
69.
The comparative diagnostic value of IgA anti-endomysium and IgA antigliadin antibodies in adults with histologically confirmed celiac disease is reported. Sera from 144 adult patients (without concurrent dermatitis herpetiformis or IgA deficiency) who underwent small bowel biopsy were analyzed for both IgA anti-endomysium and IgA anti-gliadin antibodies. Nineteen patients (13%) had celiac disease. The presence of IgA antiendomysium antibodies had a sensitivity of 74% and a specificity of 100%. The positive and negative predictive values were 100% and 96%, respectively, and the diagnostic accuracy was 97%. In contrast, IgA anti-gliadin antibodies had positive and negative predictive values of 28% and 96%, respectively, with a diagnostic accuracy of 71%. Based on these data, we suggest that small bowel biopsy is not necessary to diagnose celiac disease in symptomatic adults with IgA antiendomysium antibodies. Due to a negative predictive value of 96%, some symptomatic adults lacking anti-endomysium antibodies will not be correctly diagnosed without small bowel biopsy.  相似文献   
70.
One of the obstacles to AIDS vaccine development is the variability of HIV-1 within individuals and within infected populations, enabling viral escape from highly specific vaccine induced immune responses. An understanding of the different immune mechanisms capable of inhibiting HIV infection may be of benefit in the eventual design of vaccines effective against HIV-1 variants. To study this we first compared the immune responses induced in Rhesus monkeys by using two different immunization strategies based on the same vaccine strain of HIV-1. We then utilized a chimeric simian/HIV that expressed the envelope of a dual tropic HIV-1 escape variant isolated from a later time point from the same patient from which the vaccine strain was isolated. Upon challenge, one vaccine group was completely protected from infection, whereas all of the other vaccinees and controls became infected. Protected macaques developed highest titers of heterologous neutralizing antibodies, and consistently elevated HIV-1-specific T helper responses. Furthermore, only protected animals had markedly increased concentrations of RANTES, macrophage inflammatory proteins 1α and 1β produced by circulating CD8+ T cells. These results suggest that vaccine strategies that induce multiple effector mechanisms in concert with β-chemokines may be desired in the generation of protective immune responses by HIV-1 vaccines.  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