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   25201篇
  免费   2949篇
  国内免费   1245篇
耳鼻咽喉   193篇
儿科学   413篇
妇产科学   431篇
基础医学   1724篇
口腔科学   360篇
临床医学   2849篇
内科学   2550篇
皮肤病学   179篇
神经病学   1259篇
特种医学   910篇
外国民族医学   13篇
外科学   1846篇
综合类   5436篇
现状与发展   8篇
预防医学   2051篇
眼科学   686篇
药学   3148篇
  33篇
中国医学   3028篇
肿瘤学   2278篇
  2024年   167篇
  2023年   937篇
  2022年   1942篇
  2021年   2478篇
  2020年   2279篇
  2019年   1142篇
  2018年   1011篇
  2017年   757篇
  2016年   860篇
  2015年   952篇
  2014年   1923篇
  2013年   1689篇
  2012年   2318篇
  2011年   2317篇
  2010年   1265篇
  2009年   994篇
  2008年   628篇
  2007年   1178篇
  2006年   1009篇
  2005年   757篇
  2004年   587篇
  2003年   425篇
  2002年   370篇
  2001年   250篇
  2000年   152篇
  1999年   182篇
  1998年   160篇
  1997年   117篇
  1996年   78篇
  1995年   59篇
  1994年   58篇
  1993年   72篇
  1992年   61篇
  1991年   56篇
  1990年   39篇
  1989年   21篇
  1988年   35篇
  1987年   33篇
  1986年   31篇
  1985年   5篇
  1982年   1篇
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
1.
2.
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   
3.
目的 探究高糖饮食对小鼠真菌性角膜炎的影响。方法 选取健康无眼疾的雄性C57BL/6J小鼠78只,随机分为高糖饮食组和模型对照组,每组36只,模型对照组给予正常饮用水,高糖饮食组给予含体积分数10%果糖溶液,每2 d测量两组小鼠体质量及血糖,10 d后建立真菌性角膜炎模型。造模后24 h、36 h、48 h、72 h、96 h、120 h、168 h裂隙灯显微镜下对角膜进行临床评分并拍照。处死小鼠后,取角膜组织进行HE染色和PAS染色;测定角膜内中性粒细胞和巨噬细胞浸润体积。利用酶联免疫吸附实验对小鼠角膜内的白细胞介素-1β含量进行测定。结果 造模后 0~14 d,两组小鼠体质量与血糖差异均无统计学意义(均为P>0.05)。造模后24 h、36 h、48 h、120 h、168 h,高糖饮食组小鼠角膜临床评分均明显高于模型对照组,差异均有统计学意义(均为P<0.05)。高糖饮食组小鼠角膜穿孔率79.5%,高于模型对照组的40.9%,差异有统计学意义(P=0.000)。造模后各时间点,高糖饮食组中性粒细胞浸润体积均高于模型对照组,差异均有统计学意义(均为P=0.000)。造模后72 h、96 h、120 h、168 h,高糖饮食组巨噬细胞浸润体积均高于模型对照组(均为P=0.000)。角膜组织病理学检查结果示,高糖饮食组炎症反应更重,角膜组织破坏更早且更为严重。造模后24 h、48 h高糖饮食组白细胞介素-1β含量均明显高于模型对照组(均为P<0.05)。结论 高糖饮食加重了真菌性角膜炎感染的严重程度,增强了中性粒细胞、巨噬细胞的趋化,促进了IL-1β的分泌。  相似文献   
4.
目的 利用频域光学相干断层扫描深度增强(enhanced depth imaging spectral domain optical coherence tomography,EDI SD-OCT)观察糖尿病黄斑水肿(diabetic macular edema,DME)患者脉络膜厚度(choroidal thickness,CT)的变化及结构特点,探讨DME病变程度与CT的关系。方法 纳入2型糖尿病患者共123例204眼,其中69眼诊断为DME(DME组),135眼无黄斑水肿为对照组。DME眼依据OCT形态学特点进一步分为视网膜弥漫性增厚(diffuse retinal thickness,DRT)型(34眼)、黄斑囊样水肿(cystoid macular edema,CME)型(19眼)和浆液性视网膜脱离(serous retinal detachment,SRD)型(16眼),利用EDI-OCT分别测量黄斑中心凹下CT和以黄斑为中心上、下、鼻、颞500 μm、1000 μm、1500 μm、2000 μm处CT。结果 DME组黄斑中心凹下CT为(326.72±90.15)μm,对照组为(320.17±106.46)μm,两组之间无统计学差异,但黄斑中心凹下CT与视网膜厚度间具有明显正相关关系(r=0.270,P=0.025)。DME亚型CT分别为:DRT型(303.94±81.47)μm、CME型(304.42±73.98)μm和SRD型(401.63±88.80)μm,SRD型CT明显高于其他亚型(P<0.05),此外,SRD型的周边CT同样呈现均匀一致的增厚;鼻侧CT从500 μm至2000 μm呈距离敏感性降低(P<0.05),但SRD型鼻侧CT降低幅度明显变缓(P=0.195)。结论 SRD型黄斑水肿患者CT在中心凹下及周边部均显著增厚,CT与DME病变程度之间有一定相关性。  相似文献   
5.
Many nanoparticles (NPs) have toxic effects on multiple cell lines. This toxicity is assumed to be related to their accumulation within cells. However, the process of internalization of NPs has not yet been fully characterized. In this study, the cellular uptake, accumulation, and localization of titanium dioxide nanoparticles (TiO2 NPs) in rat (C6) and human (U373) glial cells were analyzed using time-lapse microscopy (TLM) and transmission electron microscopy (TEM). Cytochalasin D (Cyt-D) was used to evaluate whether the internalization process depends of actin reorganization. To determine whether the NP uptake is mediated by phagocytosis or macropinocytosis, nitroblue tetrazolium (NBT) reduction was measured and the 5-(N-ethyl-N-isopropyl)-amiloride was used. Expression of proteins involved with endocytosis and exocytosis such as caveolin-1 (Cav-1) and cysteine string proteins (CSPs) was also determined using flow cytometry.TiO2 NPs were taken up by both cell types, were bound to cellular membranes and were internalized at very short times after exposure (C6, 30 min; U373, 2 h). During the uptake process, the formation of pseudopodia and intracellular vesicles was observed, indicating that this process was mediated by endocytosis. No specific localization of TiO2 NPs into particular organelles was found: in contrast, they were primarily localized into large vesicles in the cytoplasm. Internalization of TiO2 NPs was strongly inhibited by Cyt-D in both cells and by amiloride in U373 cells; besides, the observed endocytosis was not associated with NBT reduction in either cell type, indicating that macropinocytosis is the main process of internalization in U373 cells. In addition, increases in the expression of Cav-1 protein and CSPs were observed.In conclusion, glial cells are able to internalize TiO2 NPs by a constitutive endocytic mechanism which may be associated with their strong cytotoxic effect in these cells; therefore, TiO2 NPs internalization and their accumulation in brain cells could be dangerous to human health.  相似文献   
6.
7.
8.
高血压病是我国发病率较高的疾病之一,西医治疗以长期服用降压药物为主要治疗方式,但常因依从性差的原因导致血压控制不佳,而用中医辨证治疗对于首次发现高血压的患者,可明显有效地降低高血压的发病率。高血压病在中医学中属"眩晕",在临床中常常会用半夏白术天麻汤来治疗眩晕,本文通过跟师医案及临床收集介绍半夏白术天麻汤治疗高血压眩晕临证方药的运用。  相似文献   
9.
Study objectiveFibrinogen concentrate is used to treat severe postpartum hemorrhage despite limited evidence of its effectiveness in obstetric settings. We aimed to explore the association between its administration and maternal outcomes in women with severe postpartum hemorrhage.Design, setting and patientsThis secondary analysis of the EPIMOMS prospective population-based study, exploring severe maternal morbidity, as defined by national expert consensus (2012–2013, 182,309 deliveries, France), included all women with severe postpartum hemorrhage and transfused with red blood cells during active bleeding.MeasurementsThe primary endpoint was maternal near-miss or death, and the secondary endpoint the total number of red blood cells units transfused.InterventionsWe studied fibrinogen concentrate administration as a binary variable and then by the timing of its administration. We used multivariable analysis and propensity score matching to account for potential indication bias.Main resultsAmong the 730 women with severe postpartum hemorrhage and transfused, 313 (42.9%) received fibrinogen concentrate, and 142 (19.5%) met near-miss criteria or died. The risk of near-miss or death was not significantly lower among the women treated with fibrinogen concentrate than among those not treated, in either the multivariable analysis (adjusted RR = 1.03; 95% CI, 0.72–1.49; P = 0.855) or the propensity score analysis (RR = 0.85; 95% CI, 0.55–1.32; P = 0.477). Among women treated with fibrinogen concentrate, administration more than three hours after red blood cell transfusion started was associated with a higher risk of near-miss or death than administration before or within 30 min after the transfusion began (adjusted RR = 2.07; 95% CI, 1.10–3.89; P = 0.024). Results were similar for the secondary endpoint.ConclusionsThe use of fibrinogen concentrate in severe postpartum hemorrhage needing red blood cell transfusion during active bleeding is not associated with improved maternal outcomes.  相似文献   
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