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   1184篇
  免费   110篇
  国内免费   252篇
耳鼻咽喉   19篇
儿科学   5篇
妇产科学   19篇
基础医学   115篇
口腔科学   9篇
临床医学   275篇
内科学   172篇
皮肤病学   11篇
神经病学   47篇
特种医学   77篇
外科学   132篇
综合类   245篇
现状与发展   1篇
预防医学   56篇
眼科学   14篇
药学   175篇
中国医学   70篇
肿瘤学   104篇
  2024年   2篇
  2023年   23篇
  2022年   27篇
  2021年   68篇
  2020年   45篇
  2019年   60篇
  2018年   56篇
  2017年   38篇
  2016年   35篇
  2015年   60篇
  2014年   66篇
  2013年   49篇
  2012年   100篇
  2011年   103篇
  2010年   58篇
  2009年   32篇
  2008年   60篇
  2007年   148篇
  2006年   50篇
  2005年   55篇
  2004年   38篇
  2003年   27篇
  2002年   27篇
  2001年   35篇
  2000年   36篇
  1999年   29篇
  1998年   24篇
  1997年   30篇
  1996年   24篇
  1995年   19篇
  1994年   11篇
  1993年   12篇
  1992年   20篇
  1991年   18篇
  1990年   14篇
  1989年   13篇
  1988年   10篇
  1987年   6篇
  1986年   3篇
  1985年   8篇
  1984年   2篇
  1983年   1篇
  1982年   2篇
  1981年   2篇
排序方式: 共有1546条查询结果,搜索用时 218 毫秒
1.
The processes involved in value evaluation and self‐control are critical when making behavioral choices. However, the evidence linking these two types of processes to behavioral choices in intertemporal decision‐making remains elusive. As the ventromedial prefrontal cortex (vmPFC), striatum, and dorsolateral prefrontal cortex (dlPFC) have been associated with these two processes, we focused on these three regions. We employed functional magnetic resonance imaging during a delayed discounting task (DDT) using a relatively large sample size, three independent samples. We evaluated how much information about a specific choice could be decoded from local patterns in each brain area using multivoxel pattern analysis (MVPA). To investigate the relationship between the dlPFC and vmPFC/striatum regions, we performed a psychophysiological interaction (PPI) analysis. In Experiment I, we found that the vmPFC and dlPFC, but not the striatum, could determine choices in healthy participants. Furthermore, we found that the dlPFC showed significant functional connectivity with the vmPFC, but not the striatum, when making decisions. These results could be replicated in Experiment II with an independent sample of healthy participants. In Experiment III, the choice‐decoding accuracy in the vmPFC and dlPFC was lower in patients with addiction (smokers and participants with Internet gaming disorder) than in healthy participants, and decoding accuracy in the dlPFC was related to impulsivity in addicts. Taken together, our findings may provide neural evidence supporting the hypothesis that value evaluation and self‐control processes both guide the intertemporal choices, and might provide potential neural targets for the diagnosis and treatment of impulsivity‐related brain disorders.  相似文献   
2.
Huang  Kangmo  Zha  Mingming  Gao  Jie  Du  Juan  Liu  Rui  Liu  Xinfeng 《Journal of thrombosis and thrombolysis》2021,51(2):536-544
Journal of Thrombosis and Thrombolysis - The impact of atrial fibrillation (AF) on outcomes of mechanical thrombectomy (MT) for acute ischemic stroke (AIS) is controversial, and with a paucity of...  相似文献   
3.
PurposeA meta-analysis aimed to systematically evaluate the safety and efficiency of I125 irradiation stent placement for patients with hepatocellular carcinoma (HCC) combined with portal vein tumor thrombosis (PVTT).Materials and methodsThe Cochrane library, PubMed/Medline, EMBASE, CNKI, Wanfang Data and CQVIP were systematically screened out from the earliest to December 2019. The qualities of all included studies were assessed. The primary endpoints were the 6-month, 12-month stent cumulative patency rate and 6-month, 12-month, 24-month overall survival rate while the secondary endpoints were the objective response rate of PVTT, main portal venous pressure changes and treatment-related adverse events. Our meta-analysis was conducted using Stata 12.0 software.ResultsTotally seven studies with 1018 patients were included in the final analysis, in which 602 patients received TACE and I125 irradiation stent placement, and 416 patients in control group underwent TACE and stent placement without endovascular brachytherapy (EVBT). Meta-analysis showed that the I125 irradiation stent improved the cumulative stent patency rates in 6 months [OR = 1.65, 95% CI (1.32–2.05), P < 0.001] and 12 months [OR = 2.55, 95% CI (1.90–3.42), P < 0.001] and the survival rates in 6 months [OR = 1.77, 95% CI (1.41–2.22), P < 0.001], 12 months [OR = 3.14, 95% CI (2.24–4.40), P < 0.001] and 24 months [OR = 7.39, 95% CI (3.55–15.41), P < 0.001]. However, there was no difference in the objective response rate of PVTT [OR = 1.13, 95% CI (0.87–1.48), P = 0.365], main portal venous pressure and the occurrence adverse event [OR = 0.88, CI = 0.72–1.08, P = 0.212] between two groups.ConclusionI125 irradiation stent seems to be more effective in treating hepatocellular carcinoma with portal vein tumor thrombosis. The usage of portal vein stent combined endovascular brachytherapy has the potential to act as an alternative therapy for HCC with PVTT. On account of the limitation of studies included, more studies with high-level evidence, such as RCTs, are requisite to support the above promising results.  相似文献   
4.
5.
Retinal degeneration (RD) results in photoreceptor loss and irreversible visual impairments. This study sought to alleviate the photoreceptor degeneration via the adeno-associated virus (AAV)-mediated erythropoietin (EPO) therapy. AAV-2/2-mCMV-EPO vectors were constructed and delivered into the subretinal space of a RD model. The retinal morphology, optokinetic behaviour and electrophysiological function of the treated animals were analysed. The subretinal delivery of AAV-2/2 vectors induced robust EPO gene expressions in the retinas. AAV2/2-mediated EPO therapy ameliorated the photoreceptor degeneration and visual impairments of the RD animal model. Furthermore, the multi-electrodes array (MEA) was used to detect the firing activities of retinal ganglion cells. MEA recording showed that the EPO therapy could restrain the spontaneous firing response, enhance the light-induced firing response and preserve the basic configurations of visual signal pathway in RD model. Our MEA assay provided an example to evaluate the potency of pharmacological compounds on retinal plasticity. In conclusion, AAV2/2-mediated EPO therapy can ameliorate the photoreceptor degeneration and rectify the abnormities in visual signal transmission. These beneficial results suggest the AAV vector is a viable therapeutic option for retinopathies with rapidly degenerating kinetics and lay the groundwork for future development of EPO gene therapy.  相似文献   
6.
7.
Osteosarcoma (OS) is one of the most common malignancies of bone. This study was aimed to explore the anti-metastatic effect of euxanthone on OS. Adhesion assay and Transwell assay were used to examine the effect of euxanthone on adhesion, migration and invasion of OS cells. COX-2-over-expressing plasmid was applied to transfect OS cells to assess whether COX-2 affects the anti-metastatic function of euxanthone. PDCD4 knockdown and miR-21 mimic were applied to assess whether euxanthone suppresses the transactivation of c-jun via modulating miR-21-PDCD4 signaling. The effect of euxanthone in vivo was also examined by lung metastasis assay. Euxanthone, a xanthone derivative extracted from Polygala caudata, has been found to exhibit anti-neoplastic activities. In present study, our results showed that euxanthone suppressed cell adhesion, migration, and invasion in OS cells. Our experimental data also showed that repression of COX-2 by euxanthone mediated its anti-metastatic activities. Moreover, our findings revealed that euxanthone modulated the COX-2 expression through the miR-21/PDCD4/c-jun signaling pathway. The anti-metastatic activities of euxanthone were also validated in a pulmonary metastasis model. Taken together, our results highlighted the potential of euxanthone to be used in the treatment of OS. Anat Rec, 302:1399–1408, 2019. © 2018 Wiley Periodicals, Inc.  相似文献   
8.
目的利用多维分析法对住院病案首页数据质量进行评价,以形成科学、系统的住院病案首页质控管理模式,提升住院病案首页填写质量。方法对某三甲医院2019年1月至12月的住院病案按照随机数字表法抽取3000份,采用多维分析法,从住院病案首页填报的完整性、准确性、住院病案首页优质率三个方面进行分析。结果该院住院病案首页数据的完整率、准确率及住院病案首页质量优质率分别为92.40%,96.03%和91.80%。住院病案首页中缺失较多的项目为RH血型、ABO血型、是否有31天再入院计划等;错误较多的项目为主要诊断、主要手术及操作及主要诊断、主要手术及操作编码。其中内科系统及重症医学科完整率高于外科系统,内科系统正确性及住院病案首页优质率高于外科系统和重症医学科,差异均有统计学意义(均P<0.05)。结论多维分析方法是住院病案首页数据质量控制的重要辅助工具,可为临床及医院管理人员进行住院病案首页数据质量控制提供科学的依据。  相似文献   
9.
目的 探讨葡萄籽原花青素(GSP)对糖尿病小鼠心脏损伤的保护作用及作用机制.方法 采用腹腔注射四氧嘧啶制备1型糖尿病模型,造模成功后,随机分为模型组、GSP低、中、高剂量组(65、130、195 mg/kg)和二甲双胍(MET)阳性对照组(220 mg/kg).同时设置空白对照组,各组灌胃给药30 d,对照和模型组给予0.9%氯化钠溶液灌胃.给药期间记录动态血糖、糖耐量和饮食饮水量的变化.连续给药30 d后,采用BL-420S生物机能实验系统检测小鼠心功能并计算心脏重量指数(HWI)和肾脏重量指数(KWI);苏木精-伊红(HE)染色和马松(Masson)染色观察组织病理学变化;酶联免疫吸附法和比色法检测血清学指标的改变;免疫荧光法和Western blot检测心脏组织蛋白表达的变化.结果 与对照组相比,模型组小鼠血糖、糖耐量、饮食饮水量明显升高;血流动力学、病理形态学、血清学指标发生明显异常改变,如心肌组织内皮素A(ETA)明显升高,内皮型一氧化氮合酶(eNOS)明显降低等.与模型组相比,给药组和MET组均能显著改善上述指标.结论 GSP对糖尿病心脏损伤具有一定的保护作用,其机制可能与抗氧化应激和改善内皮功能障碍有关.  相似文献   
10.
Cholinesterases (ChEs) have been identified in vertebrates and invertebrates. Inhibition of ChE activity in invertebrates, such as bivalve molluscs, has been used to evaluate the exposure of organophosphates, carbamate pesticides, and heavy metals in the marine system. The golden apple snail (Pomacea canaliculata) is considered as one of the worst invasive alien species harmful to rice and other crops. The ChE(s) in this animal, which has been found recently, but poorly characterized thus far, could serve as biomarker(s) for environmental surveillance as well as a potential target for the pest control. In this study, the tissue distribution, substrate preference, sensitivity to ChE inhibitors, and molecular species of ChEs in P. canaliculata were investigated. It was found that the activities of both AChE and BChE were present in all test tissues. The intestine had the most abundant ChE activities. Both enzymes had fair activities in the head, kidney, and gills. The BChE activity was more sensitive to tetra-isopropylpyrophosphoramide (iso-OMPA) than the AChE. Only one BChE molecular species, 5.8S, was found in the intestine and head, whereas two AChE species, 5.8S and 11.6S, were found there. We propose that intestine ChEs of this snail may be potential biomarkers for manipulating pollutions.  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