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   55341篇
  免费   5323篇
  国内免费   1774篇
耳鼻咽喉   237篇
儿科学   1971篇
妇产科学   709篇
基础医学   4239篇
口腔科学   423篇
临床医学   5295篇
内科学   6934篇
皮肤病学   479篇
神经病学   2142篇
特种医学   1567篇
外国民族医学   2篇
外科学   13697篇
综合类   8753篇
现状与发展   3篇
一般理论   1篇
预防医学   3861篇
眼科学   482篇
药学   5565篇
  36篇
中国医学   3671篇
肿瘤学   2371篇
  2024年   81篇
  2023年   1184篇
  2022年   1509篇
  2021年   3146篇
  2020年   2527篇
  2019年   2450篇
  2018年   2355篇
  2017年   2328篇
  2016年   2479篇
  2015年   2459篇
  2014年   4282篇
  2013年   4576篇
  2012年   3350篇
  2011年   3687篇
  2010年   2969篇
  2009年   2640篇
  2008年   2675篇
  2007年   2384篇
  2006年   2238篇
  2005年   1861篇
  2004年   1586篇
  2003年   1332篇
  2002年   1098篇
  2001年   1016篇
  2000年   753篇
  1999年   599篇
  1998年   487篇
  1997年   390篇
  1996年   407篇
  1995年   368篇
  1994年   359篇
  1993年   288篇
  1992年   301篇
  1991年   274篇
  1990年   210篇
  1989年   223篇
  1988年   189篇
  1987年   164篇
  1986年   130篇
  1985年   151篇
  1984年   149篇
  1983年   113篇
  1982年   104篇
  1981年   100篇
  1980年   83篇
  1979年   104篇
  1978年   63篇
  1977年   50篇
  1976年   48篇
  1975年   30篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
IntroductionLung cancer (LC) is usually diagnosed at advanced stages with only a 12% 5-year survival. Trials as NLST and NELSON show a mortality decrease, which justifies implementation of lung cancer screening in risk population. Our objective was to show survival results of the largest LC screening program in Spain with low dosage computed tomography (LDCT).MethodsClinical records from International Early Lung Cancer Detection Program (IELCAP) at Valencia, Spain were analysed. This program recruited volunteers, ever-smokers aged 40-80 years, since 2008. Results are compared to those from other similar sizeable programs.ResultsA total of 8278 participants were screened with at least two-rounds until November 2020. A mean of 6 annual screening rounds were performed. We detected 239 tumours along 12-year follow-up. Adenocarcinoma was the most common histology, being 61.3% at stage I. The lung cancer prevalence and incidence proportion was 1.5% and 1.4%, respectively with an annual detection rate of 0.17. One-year survival and 10-year survival were 90% and 80.1%, respectively. Adherence was 96.84%.ConclusionLargest lung cancer screening in Spain shows that survival is improved when is performed in multidisciplinary team experienced in management of LC, and is comparable to similar screening programs.  相似文献   
2.
IntroductionThis study was designed to assess whether a dental caries management protocol combining a single application of 38% silver diamine fluoride (SDF) with comprehensive oral health education will successfully divert high-risk children from dental treatment under dental general anaesthesia (DGA), arrest active caries in primary teeth, and improve parent-reported child oral health–related quality of life (OHRQoL).MethodsChildren aged 2 to 10 years, who attended two public dental agencies in Victoria, Australia, and were unable to tolerate restorative treatments in the clinic setting, elected to participate in either a 38% SDF intervention protocol or, alternatively, referral for DGA. Follow-up examinations were completed at 6 months to assess caries progression, decayed missing filled tooth index, PUFA index (pulpal involvement, ulceration, fistula, abscess), DGA referral rates, and OHRQoL (Early Childhood Oral Health Impact Scale [ECOHIS]).ResultsOf the total sample, 89.5% of children (n = 102) [mean (SD) age, 4.1 (1.0) years] with 401 active carious lesions elected to participate in the 38% SDF protocol; 10.5% (n = 12) of parents opted for referral for treatment under DGA. The proportion of active caries subsequently arrested at follow-up (number of arrested lesions/number of lesions treated) was 0.78 (95% CI, 0.69 to 0.87). There was an 88% reduction in referrals for DGA in eligible children over the 6-month period. The 38% SDF intervention group showed a significant improvement in ECOHIS scores at follow-up (P < .001).DiscussionAdoption of the 38% SDF intervention protocol resulted in a significant reduction in the rate of preventable dental hospitalisations. Most parents opted against referral for DGA. Parent-reported OHRQoL for children improved significantly.  相似文献   
3.
4.
【摘要】目的 探讨二维斑点追踪显像技术(2D-STI)评估新生儿窒息合并心肌损害后左心室整体及局部心肌的纵向收缩功能在早期诊断窒息新生儿心肌损害中的临床价值。方法 选择2019年07月至2020年12月期间在右江民族医学院附属医院新生儿科住院的足月窒息新生儿61例,经临床确诊合并心肌损害,根据Apgar评分分为轻度组31例和重度组30例,选择同期住院出生的正常足月新生儿30例作为对照组。检测受检者的血清肌酸激酶同工酶(CK-MB)、肌钙蛋白(cTnT)、左室舒张期前后径(LVDId)、左室射血分数(LVEF)、左室短轴缩短率(LVFS)、辛普森法左室射血分数(Simpson EF)、左室三腔心整体应变(GLS-LAX)、左室四腔心整体应变(GLS-A4C)、左室两腔心整体应变(GLS-A2C)、左室整体应变(GLS-AVG),分析GLS-AVG和CK-MB、cTnT三者的相关性。结果 三组间CK-MB和cTnT比较差异有统计学意义(P<0.05)。三组间性别、体重、胎龄均无统计学差异(P>0.05)。三组间LVDId、LVEF、LVFS、Simpson EF比较差异无统计学意义(P>0.05)。GLS-AVG与CK-MB呈负性相关(r=-0.515,P=0.000),GLS-AVG与cTnT呈负性相关(r=-0.912,P=0.000)。结论 GLS-AVG与CK-MB、cTnT具有相关性,GLS-AVG可作为窒息新生儿心肌损害早期诊断指标。  相似文献   
5.
The main aim of the paper is to discuss current knowledge on how Age Related Macular Degeneration (AMD) affects Dark Adaptation (DA). The paper is divided into three parts. Firstly, we outline some of the molecular mechanisms that control DA. Secondly, we review the psychophysical issues and the corresponding analytical techniques. Finally, we characterise the link between slowed DA and the morphological abnormalities in early AMD.Historically, DA has been regarded as too cumbersome for widespread clinical application. Yet the technique is extremely useful; it is widely accepted that the psychophysically obtained slope of the second rod-mediated phase of the dark adaptation function is an accurate assay of photoreceptor pigment regeneration kinetics. Technological developments have prompted new ways of generating the DA curve, but analytical problems remain. A simple potential solution to these, based on the application of a novel fast mathematical algorithm, is presented. This allows the calculation of the parameters of the DA curve in real time.Improving current management of AMD will depend on identifying a satisfactory endpoint for evaluating future therapeutic strategies. This must be implemented before the onset of severe disease. Morphological changes progress too slowly to act as a satisfactory endpoint for new therapies whereas functional changes, such as those seen in DA, may have more potential in this regard. It is important to recognise, however, that the functional changes are not confined to rods and that building a mathematical model of the DA curve enables the separation of rod and cone dysfunction and allows more versatility in terms of the range of disease severity that can be monitored. Examples are presented that show how analysing the DA curve into its constituent components can improve our understanding of the morphological changes in early AMD.  相似文献   
6.
《Clinical microbiology and infection》2022,28(8):1152.e1-1152.e6
ObjectivesDespite the possibility of concurrent infection with COVID-19 and malaria, little is known about the clinical course of coinfected patients. We analysed the clinical outcomes of patients with concurrent COVID-19 and malaria infection.MethodsWe conducted a retrospective cohort study that assessed prospectively collected data of all patients who were admitted between May and December 2020 to the Universal COVID-19 treatment center (UCTC), Khartoum, Sudan. UCTC compiled demographic, clinical, laboratory (including testing for malaria), and outcome data in all patients with confirmed COVID-19 hospitalized at that clinic. The primary outcome was all-cause mortality during the hospital stay. We built proportional hazard Cox models with malaria status as the main exposure and stepwise adjustment for age, sex, cardiovascular comorbidities, diabetes, and hypertension.ResultsWe included 591 patients with confirmed COVID-19 diagnosis who were also tested for malaria. Mean (SD) age was 58 (16.2) years, 446/591 (75.5%) were males. Malaria was diagnosed in 270/591 (45.7%) patients. Most malaria patients were infected by Plasmodium falciparum (140/270; 51.9%), while 121/270 (44.8%) were coinfected with Plasmodium falciparum and Plasmodium vivax. Median follow-up was 29 days. Crude mortality rates were 10.71 and 5.87 per 1000 person-days for patients with and without concurrent malaria, respectively. In the fully adjusted Cox model, patients with concurrent malaria and COVID-19 had a greater mortality risk (hazard ratio 1.43, 95% confidence interval 1.21-1.69).DiscussionCoinfection with COVID-19 and malaria is associated with increased all-cause in-hospital mortality compared to monoinfection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).  相似文献   
7.
8.
BackgroundTo evaluate the association of neutrophil-to-lymphocyte ratio (NLR) with recurrence-free survival (RFS) and overall survival (OS) in patients with locally advanced nonmetastatic clear cell renal cell carcinoma (ccRCC) undergoing radical nephrectomy.Material and MethodsWe retrospectively identified 880 nephrectomies performed between January 2009 and December 2016 in a single center, reviewed data from 478 radical nephrectomies for kidney tumors and identified 187 patients with locally advanced nonmetastatic ccRCC (pT3-T4 N0M0). NLR was obtained preoperatively and calculated by dividing absolute neutrophil count by absolute lymphocyte count. OS and RFS were evaluated by the Kaplan–Meier method. Cox proportional-hazards regression models were used to evaluate predictors of RFS and OS.ResultsAmong 187 patients with ccRCC (mean age 63.4 ± 11.5 years; 118 [63.1%] male), the median follow-up was 48.7 months. On univariate analysis, in patients with Fuhrman nuclear grade of differentiation 3-4, the median time to recurrence was significantly shorter with NLR ≥ 4 than < 4 (24 vs. 55 months, P = .045). On multivariable analysis adjusted for NLR ≥ 4, among all variables analyzed (NLR, microvascular invasion, sarcomatoid differentiation, tumor size and body mass index), only nuclear grade of differentiation was an independent predictor of recurrence (hazard ratio 2.18; 95% confidence interval 1.07-4.92, P = .03). The 3-year OS had no statistically significant difference between patients with NLR ≥ 4 or < 4.ConclusionFor patients with locally advanced, nonmetastatic ccRCC, RFS was reduced with high nuclear grade of differentiation and high preoperative NLR. These findings suggest an association between higher NLR and worse outcomes in locally advanced ccRCC.  相似文献   
9.
10.
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