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   24956篇
  免费   2556篇
  国内免费   504篇
耳鼻咽喉   136篇
儿科学   487篇
妇产科学   721篇
基础医学   1334篇
口腔科学   1292篇
临床医学   3159篇
内科学   4133篇
皮肤病学   512篇
神经病学   1691篇
特种医学   312篇
外国民族医学   4篇
外科学   2399篇
综合类   2035篇
现状与发展   1篇
预防医学   2383篇
眼科学   253篇
药学   3389篇
  9篇
中国医学   1806篇
肿瘤学   1960篇
  2024年   128篇
  2023年   731篇
  2022年   1011篇
  2021年   1498篇
  2020年   1274篇
  2019年   1340篇
  2018年   1294篇
  2017年   1180篇
  2016年   1005篇
  2015年   926篇
  2014年   1927篇
  2013年   2455篇
  2012年   1376篇
  2011年   1328篇
  2010年   1082篇
  2009年   1083篇
  2008年   1119篇
  2007年   1089篇
  2006年   1005篇
  2005年   895篇
  2004年   715篇
  2003年   569篇
  2002年   500篇
  2001年   365篇
  2000年   291篇
  1999年   269篇
  1998年   218篇
  1997年   168篇
  1996年   149篇
  1995年   116篇
  1994年   124篇
  1993年   74篇
  1992年   80篇
  1991年   68篇
  1990年   73篇
  1989年   65篇
  1988年   53篇
  1987年   45篇
  1986年   40篇
  1985年   53篇
  1984年   45篇
  1983年   33篇
  1982年   19篇
  1981年   28篇
  1980年   25篇
  1979年   21篇
  1978年   12篇
  1977年   11篇
  1976年   10篇
  1975年   12篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
2‐deoxy D‐glucose (2DG) was tested for efficacy in treating alopecia areata using the C3H/HeJ skin graft model. 2DG has proven to be efficacious in treatment of various mouse models of autoimmunity with minimal serious side effects noted. This agent has been shown to normalize abnormally activated T‐cell populations while also preventing cell surface expression of NKG2D; key factors defining alopecia areata disease progression. Daily oral ingestion of 2DG via drinking water to mice with patchy or diffuse alopecia areata for 16 weeks failed to prevent expansion of alopecia or cause regrowth of hair in treated mice. Histologically, there were no differences between treated and control groups. These results indicate that, while 2DG is effective for some autoimmune diseases, it was not efficacious for the cell‐mediated autoimmune mouse disease, alopecia areata.  相似文献   
32.
《Vaccine》2016,34(38):4635-4641
BackgroundBroad use of monovalent Haemophilus influenzae type b (Hib) conjugate vaccines based on the capsular polysaccharide polyribosyl-ribitol phosphate (PRP), has significantly reduced invasive Hib disease burden in children worldwide, particularly in children aged <1 year. In Japan, PRP conjugated to tetanus toxoid (PRP-T) vaccine has been widely used since the initiation of public funding programs followed by a routine vaccination designation in 2013.MethodsWe compared the immunogenicity and safety of PRP conjugated to a non-toxic diphtheria toxin mutant (PRP-CRM197) vaccine with the PRP-T vaccine when administered subcutaneously to healthy Japanese children in a phase III study. Additionally, we evaluated the immunogenicity and safety profiles of a diphtheria–tetanus acellular pertussis (DTaP) combination vaccine when concomitantly administered with either PRP-CRM197 or PRP-T vaccines. The primary endpoint was the “long-term seroprotection rate”, defined as the group proportion with anti-PRP antibody titers ⩾1.0 μg/mL, after the primary series.ResultsLong-term seroprotection rates were 99.3% in the PRP-CRM197 group and 95.6% in the PRP-T group. The intergroup difference (PRP-CRM197 group – PRP-T group) was 3.7% (95% confidence interval: 0.099–7.336), demonstrating that PRP-CRM197 vaccine was non-inferior to PRP-T vaccine (p < 0.0001). Furthermore, the “short-term seroprotection rate” (anti-PRP antibody titer ⩾0.15 μg/mL) before booster vaccination was higher in the PRP-CRM197 group than in PRP-T. Concomitant administration of PRP-CRM197 vaccine with DTaP vaccine showed no differences in terms of immunogenicity compared with concomitant vaccination with PRP-T vaccine and DTaP vaccine. Although CRM197 vaccine had higher local reactogenicity, overall, both Hib vaccines had acceptable safety and tolerability profiles.ConclusionThe immunogenicity of PRP-CRM197 vaccine administered subcutaneously as a three-dose primary series in children followed by a booster vaccination 1 year after the primary series induced protective levels of Hib antibodies with no safety or tolerability concerns.Clinical trial registry: Registered on ClinicalTrials.gov: NCT01379846  相似文献   
33.
IntroductionDural puncture epidural (DPE) analgesia is a modification of conventional epidural analgesia that involves the intentional puncture of the dura with a spinal needle through the needle placed in the epidural space, without a medication being injected intrathecally. There have been contradictory findings regarding better analgesia and better block quality.MethodsA systematic literature search was done to identify randomized controlled trials (RCT) comparing DPE with epidural analgesia. The risk of bias was assessed with the Cochrane tool. Risk ratio and 95% confidence intervals were calculated.ResultsFive RCTs including 581 patients were identified. One RCT on caesarean section was excluded. Single studies suggested slightly better analgesia by finding a median time to achieve sufficient analgesia of two minutes less in the DPE group, a higher number of women having a pain score <10/100 at 20 min, a reduction in the number of epidural top-ups and better sacral spread. The studies did not show a difference between DPE and epidural analgesia for catheter replacement or manipulation rates, the incidence of intravascular placement or unilateral block.ConclusionThere is a lack of clear evidence on either the benefits or the risks of the DPE technique, such that a recommendation for or against its routine use is premature. Two of the three studies showing a beneficial effect of DPE came from the same institution and replication of the findings by other groups is warranted.  相似文献   
34.
35.
BackgroundMedication adherence is crucial for improving clinical outcomes in the treatment of patients. We evaluate the effect of short message service (SMS) reminder on medication adherence and serum hormones in patients with breast cancer on aromatase inhibitors.MethodsAn open-label, multi-centre, prospective randomised controlled trial of SMS versus Standard Care was conducted. Medication adherence was assessed via self-report using the Simplified Medication Adherence Questionnaire at baseline, 6 month, and 1 year. Androstenedione, estradiol, and estrone were measured at baseline and 1 year. The χ2 test and mixed effects logistic regression was performed to compare medication adherence between groups. Difference in androstenedione and estrone levels were assessed using analysis of covariance, whereas χ2 test and logistic regression was used for estradiol. Analysis was based on intention-to-treat.ResultsA total of 244 patients were randomised to receive weekly SMS reminder (n = 123) or Standard Care (n = 121) between May 2015 and December 2018. The odds of adherence was higher at 6-month in SMS (OR = 1.78, 95% CI 1.04–3.05, p = 0.034), and not significantly different at 1-year (OR = 1.15, 95% CI: 0.67–1.96 p = 0.617). Mixed effects logistic regression analysis showed higher odds of adherence in SMS over the 1-year period (OR = 2.35, 95% CI: 1.01–5.49, p = 0.048). There was no difference in serum hormone levels between groups.ConclusionSMS reminder improved medication adherence in the short-term but had no effect on serum hormones levels in the longer term. Future studies could investigate the use of tailored SMS intervention according to patient preference to improve its sustainability.  相似文献   
36.
It is well known that a meta-analysis of randomized controlled trials aims to increase the power and precision of the estimated intervention effects. However, when a meta-analysis includes a limited number of patients and a small number of events, overestimation of intervention effect estimates may occur and could cause spurious results. Although many biases can cause the overestimation, random error may be the most common cause. Trial sequential analysis (TSA) can explore the independent effect of random error on intervention effect estimates in meta-analyses and protect meta-analyses against overestimation due to random error.  相似文献   
37.
《Value in health》2020,23(10):1340-1348
ObjectivesWe applied principles for conducting economic evaluations of factorial trials to a trial-based economic evaluation of a cluster-randomized 2 × 2 × 2 factorial trial. We assessed the cost-effectiveness of atorvastatin, omega-3 fish oil, and an action-planning leaflet, alone and in combination, from a UK National Health Service perspective.MethodsThe Atorvastatin in Factorial With Omega EE90 Risk Reduction in Diabetes (AFORRD) Trial randomized 800 patients with type 2 diabetes to atorvastatin, omega-3, or their respective placebos and randomized general practices to receive a leaflet-based action-planning intervention designed to improve compliance or standard care. The trial was conducted at 59 UK general practices. Sixteen-week outcomes for each trial participant were extrapolated for 70 years using the United Kingdom Prospective Diabetes Study Outcomes Model v2.01. We analyzed the trial as a 2 × 2 factorial trial (ignoring interactions between action-planning leaflet and medication), as a 2 × 2 × 2 factorial trial (considering all interactions), and ignoring all interactions.ResultsWe observed several qualitative interactions for costs and quality-adjusted life-years (QALYs) that changed treatment rankings. However, different approaches to analyzing the factorial design did not change the conclusions. There was a ≥99% chance that atorvastatin is cost-effective and omega-3 is not, at a £20 000/QALY threshold.ConclusionsAtorvastatin monotherapy was the most cost-effective combination of the 3 trial interventions at a £20 000/QALY threshold. Omega-3 fish oil was not cost-effective, while there was insufficient evidence to draw firm conclusions about action planning. Recently-developed methods for analyzing factorial trials and combining parameter and sampling uncertainty were extended to estimate cost-effectiveness acceptability curves within a 2x2x2 factorial design with model-based extrapolation.  相似文献   
38.
OBJECTIVES: To assess the effectiveness and safety of additional bedtime H2‐receptor antagonists (H2RAs) in suppressing nocturnal gastric acid breakthrough (NAB) via a systematic review. METHODS: Eligible trials were identified by searching the Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library Issue 2, 2004), MEDLINE (January 1966–June 2004), EMBASE (January 1980–June 2004) and CINAHL (January 1982–June 2004). Additional hand‐searching was conducted on the proceedings of correlated conferences, eight important Chinese journals and references of all included trials. All randomized controlled trials evaluating H2RAs for the control of NAB were eligible for inclusion. The systematic review was conducted using methods recommended by The Cochrane Collaboration. RESULTS: Only two randomized crossover studies, comprising 32 participants, met the inclusion criteria. Because the design, dosage and duration of the treatments were different between the studies, it was not possible to conduct meta‐analysis. There were no consistent conclusions found between the two included studies in evaluating H2RAs for the control of NAB. CONCLUSIONS: No implications for practice at this stage can be concluded. Appropriately designed large‐scale randomized controlled trials with long‐term follow up are needed to determine the effects of additional bedtime H2RAs in suppressing NAB.  相似文献   
39.
40.
BACKGROUND: Computer-assisted image analysis has been proposed for human hair growth studies. METHODS: The performances of Trichoscan, a commercially available automated system combining epiluminiscence microscopy with digital image analysis, developed for office-based hair growth measurements, have been evaluated comparatively on the same skin sites using standardized photographic equipment and calibrated processing for contrast-enhanced phototrichogram (CE-PTG) analysis. This reference method has been validated with scalp biopsies and histological examination of serial sectioning. RESULTS: Besides edge effects, hair fibres escaped the Trichoscan analysis for various reasons including, but not limited to, thickness, pigmentation, closeness and crossing. CONCLUSION: Most of these problems have been identified in the late 1980s and remain largely unsolved by the processing software that was evaluated in 2004. Therefore claims promoting the Trichoscan method for accurate hair measurements in clinical trials on scalp and body hair are not supported by the present investigation. The speed at which the analysis is performed is outweighed by the errors in signal detection. Therefore we suggest that improvements must be clearly documented before Trichoscan is established for quantified diagnostic purposes and detailed hair cycle monitoring during hair trials.  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