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   445005篇
  免费   48274篇
  国内免费   11784篇
耳鼻咽喉   4374篇
儿科学   6453篇
妇产科学   9138篇
基础医学   35110篇
口腔科学   10145篇
临床医学   40331篇
内科学   45632篇
皮肤病学   4193篇
神经病学   14277篇
特种医学   12845篇
外国民族医学   260篇
外科学   50623篇
综合类   62194篇
现状与发展   51篇
一般理论   28篇
预防医学   45100篇
眼科学   2568篇
药学   38629篇
  491篇
中国医学   31974篇
肿瘤学   90647篇
  2024年   1043篇
  2023年   8645篇
  2022年   13059篇
  2021年   22715篇
  2020年   21623篇
  2019年   21721篇
  2018年   20220篇
  2017年   19212篇
  2016年   18990篇
  2015年   20054篇
  2014年   33572篇
  2013年   34564篇
  2012年   28143篇
  2011年   29478篇
  2010年   22630篇
  2009年   21339篇
  2008年   20862篇
  2007年   20086篇
  2006年   17596篇
  2005年   14454篇
  2004年   12132篇
  2003年   10444篇
  2002年   8503篇
  2001年   7405篇
  2000年   6259篇
  1999年   5269篇
  1998年   4313篇
  1997年   3874篇
  1996年   3183篇
  1995年   2999篇
  1994年   2544篇
  1993年   2162篇
  1992年   1907篇
  1991年   1725篇
  1990年   1447篇
  1989年   1363篇
  1988年   1226篇
  1987年   1095篇
  1986年   959篇
  1985年   2328篇
  1984年   2497篇
  1983年   1586篇
  1982年   2014篇
  1981年   1475篇
  1980年   1262篇
  1979年   1061篇
  1978年   853篇
  1977年   644篇
  1976年   790篇
  1975年   534篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
92.
BackgroundIsolated local recurrent or persistent esophageal cancer (EC) after curative intended definitive (dCRT) or neoadjuvant chemoradiotherapy (nCRT) with initially omitted surgery, is a potential indication for salvage surgery. We aimed to evaluate safety and efficacy of salvage surgery in these patients.Material and methodsA systematic literature search following PRISMA guidelines was performed using databases of PubMed/Medline. All included studies were performed in patients with persistent or recurrent EC after initial treatment with dCRT or nCRT, between 2007 and 2017. Survival analysis was performed with an inverse-variance weighting method.ResultsOf the 278 identified studies, 28 were eligible, including a total of 1076 patients. Postoperative complications after salvage esophagectomy were significantly more common among patients with isolated persistent than in those with locoregional recurrent EC, including respiratory (36.6% versus 22.7%; difference in proportion 10.9 with 95% confidence interval (CI) [3.1; 18.7]) and cardiovascular complications (10.4% versus 4.5%; difference in proportion 5.9 with 95% CI [1.5; 10.2]). The pooled estimated 30- and 90-day mortality was 2.6% [1.6; 3.6] and 8.0% [6.3; 9.8], respectively. The pooled estimated 3-year and 5-year overall survival (OS) were 39.0% (95% CI: [35.8; 42.2]) and 19.4% [95% CI:16.5; 22.4], respectively. Patients with isolated persistent or recurrent EC after initial CRT had similar 5-year OS (14.0% versus 19.7%, difference in proportion −5.7, 95% CI [-13.7; 2.3]).ConclusionsSalvage surgery is a potentially curative procedure in patients with locally recurrent or persistent esophageal cancer and can be performed safely after definitive or neoadjuvant chemoradiotherapy when surgery was initially omitted.  相似文献   
93.
Objective: The objective of this study is to evaluate the efficacy and safety of the clearing the lung and dissipating phlegm method in the treatment of acute exacerbation of chronic obstructive pulmonary disease(COPD) and to provide evidence for the treatment of the disease. Materials and Methods: Literature was searched from the United States National Library of Medicine(PubMed), Embase, Cochrane Library, China National Knowledge Infrastructure, Wanfang Database(Wanfang), and the Full?Text Database of Chinese Scientific and Technical Periodicals(VIP).A comprehensive collection was made of randomized controlled trials(RCTs) before June 2018, in which the treatment groups used either the clearing the lung and dissipating phlegm formulas only or combined it with routine Western medicine therapy, and the control group adopted routine Western medicine therapy only for the acute exacerbation of COPD. The Cochrane risk of bias method was used to evaluate the quality of the literature. The data were analyzed and retrieved independently by two reviewers before meta?analysis was carried out with RevMan 5.3 software to evaluate the primary outcome measures, including the total clinical effective rate, and the secondary outcome measures such as the pulmonary function(forced vital capacity [FVC], forced expiratory volume in the 1 s [FEV1], percentage of FEV1 [FEV1%], and FEV1/FVC)and blood gases(PaO_2 and PaCo_2). Results: A total of 13 RCTs involving 990 patients(496 in the treatment group and 494 in the control group)were included in this study. Meta?analysis revealed significant difference in the efficacy of the group that adopted solely the routine Western medicine method and the group that combined the Western medicine with the clearing the lung and dissipating phlegm method. Outcome measures including the pulmonary function(FVC, FEV1, FEV1%, and FEV1/FVC) and the blood gases(PaO_2 and PaCo_2) were significantly improved as compared to the control group(P 0.00001). However, adverse effects in the treatment group using combined traditional Chinese medicine were not reported due to the short observation time of the study. Conclusion: The clearing the lung and dissipating phlegm method can improve the efficacy in the treatment of acute exacerbation of COPD, the outcome measures of the pulmonary function and the blood gases,as well as the life quality of the patients. However, due to the fact that the existing studies are generally of poor quality in which randomization and its implementation were not properly carried out, more high?quality RCTs are necessary to confirm the findings of this study.  相似文献   
94.
95.
ARID1A, one of the subunits in SWI/SNF chromatin remodeling complex, is frequently mutated in gastric cancers with microsatellite instability (MSI). The most frequent MSI in solid‐type poorly differentiated adenocarcinoma (PDA) has been reported, but the SWI/SNF complex status in solid‐type PDA is still largely unknown. We retrospectively analyzed 54 cases of solid‐type PDA for the expressions of mismatch repair (MMR) proteins (MLH1, PMS2, MSH2, and MSH6), SWI/SNF complex subunits (ARID1A, INI1, BRG1, BRM, BAF155, and BAF170) and EBER, and mutations in KRAS and BRAF. We analyzed 40 cases of another histological type of gastric cancer as a control group. The solid‐type PDAs showed coexisting glandular components (76%), MMR deficiency (39%), and complete/partial loss of ARID1A (31%/7%), INI1 (4%/4%), BRG1 (48%/30%), BRM (33%/33%), BAF155 (13%/41%), and BAF170 (6%/2%), EBER positivity (4%), KRAS mutation (2%), and BRAF mutation (2%). Compared to the control group, MMR deficiency and losses of ARID1A, BRG1, BRM, and BAF155 were significantly frequent in solid‐type PDAs. Mismatch repair deficiency was associated with the losses of ARID1A, BRG1, and BAF155 in solid‐type PDAs. In the MMR‐deficient group, solid components showed significantly more frequent losses of ARID1A, BRG1, BRM, and BAF155 compared to glandular components (P = .0268, P = .0181, P = .0224, and P = .0071, respectively). In the MMR‐proficient group, solid components showed significantly more frequent loss of BRG1 compared to glandular components (P = .012). In conclusion, solid‐type PDAs showed frequent losses of MMR proteins and the SWI/SNF complex. We suggest that loss of the SWI/SNF complex could induce a morphological shift from differentiated‐type adenocarcinoma to solid‐type PDA.  相似文献   
96.
97.
PurposeTo evaluate tumor and ablation zone morphology and densitometry related to tumor recurrence in participants with Stage IA non–small cell lung cancer undergoing radiofrequency ablation in a prospective, multicenter trial.Materials and MethodsForty-five participants (median 76 years old; 25 women; 20 men) from 16 sites were followed for 2 years (December 2006 to November 2010) with computed tomography (CT) densitometry. Imaging findings before and after ablation were recorded, including maximum CT attenuation (in Hounsfield units) at precontrast and 45-, 90-, 180-, and 300-s postcontrast.ResultsEvery 1-cm increase in the largest axial diameter of the ablation zone at 3-months’ follow-up compared to the index tumor reduced the odds of 2-year recurrence by 52% (P = .02). A 1-cm difference performed the best (sensitivity, 0.56; specificity, 0.93; positive likelihood ratio of 8). CT densitometry precontrast and at 45 seconds showed significantly different enhancement patterns in a comparison among pretreated lung cancer (delta = +61.2 HU), tumor recurrence (delta = +57 HU), and treated tumor/ablation zone (delta [change in attenuation] = +16.9 HU), (P < .0001). Densitometry from 45 to 300 s was also different among pretreated tumor (delta = −6.8 HU), recurrence (delta = −11.2 HU), and treated tumor (delta = +12.1 HU; P = .01). Untreated and residual tumor demonstrated washout, whereas treated tumor demonstrated increased attenuation.ConclusionsAn ablation zone ≥1 cm larger than the initial tumor, based on 3-month follow-up imaging, is recommended to decrease odds of recurrence. CT densitometry can delineate tumor versus treatment zones.  相似文献   
98.
目前临床研究已证实腹腔镜胃癌根治术治疗早期胃癌的安全性、可行性和有效性。基于此,第4版日本《胃癌治疗指南》推荐腹腔镜手术治疗临床Ⅰ期远端胃癌。然而,腹腔镜胃癌手术治疗进展期胃癌的有效性和安全性仍存争议。中国腹腔镜胃肠外科研究组(CLASS研究组)发起的CLASS-01研究顺利完成,提供了全球首个局部进展期胃癌腹腔镜手术安全性和疗效的前瞻性多中心证据。胃癌外科的主流方向在从“大切口和扩大化手术切除”逐渐向“微创、精准化手术”转变,以使手术安全性和病人术后生活质量最优化。  相似文献   
99.
100.
目的:探索以系统化、标准化的新型冠状病毒核酸检测为核心和重要组成部分,建立适合于眼科医院新冠疫情精准防控切实可行的防控体系。方法:系列病例研究。自2020年2月24日至3月2日期间,以标准化病毒核酸检测联合血常规、C反应蛋白(CRP)、血清淀粉样蛋白A(SAA)等检测作为所有眼科手术患者术前筛查常规检测项目,同时也为返岗员工提供病毒核酸检测。设计调查问卷了解受检者对鼻咽拭子采样的接受度以及核酸检测结果对其心理状态的影响。结果:99例患者血液学检测结果有一定的异常比例,其中SAA检测结果增高13例,淋巴细胞计数减低12例、增高5例,白细胞计数增高11例、减低1例,CRP增高2例,新型冠状病毒核酸检测均阴性。33例本院职工新型冠状病毒核酸检测均阴性。12%的受访者对鼻咽拭子采样接受度评分较低。受检者在核酸检测前后思想压力评分较高的比例分别为46.7%和6.7%。结论:该项举措一方面为术前新冠病毒肺炎筛查及鉴别诊断提供了客观依据,很大程度上排除了隐性无症状感染者传播的可能,有利于减少二次传播的风险,降低院内交叉感染的概率;另一方面,核酸检测阴性结果有利于调整患者术前的心理状态并缓解医护人员在疫情防控期间的心理压力。  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