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   40214篇
  免费   4115篇
  国内免费   2862篇
耳鼻咽喉   300篇
儿科学   585篇
妇产科学   517篇
基础医学   3521篇
口腔科学   590篇
临床医学   5497篇
内科学   4991篇
皮肤病学   345篇
神经病学   1504篇
特种医学   1336篇
外国民族医学   7篇
外科学   3133篇
综合类   8971篇
现状与发展   23篇
一般理论   1篇
预防医学   3681篇
眼科学   797篇
药学   5109篇
  54篇
中国医学   3329篇
肿瘤学   2900篇
  2024年   156篇
  2023年   559篇
  2022年   1492篇
  2021年   1854篇
  2020年   1530篇
  2019年   1160篇
  2018年   1172篇
  2017年   1337篇
  2016年   1108篇
  2015年   1877篇
  2014年   2332篇
  2013年   2416篇
  2012年   3607篇
  2011年   3626篇
  2010年   2728篇
  2009年   2237篇
  2008年   2571篇
  2007年   2619篇
  2006年   2390篇
  2005年   2106篇
  2004年   1491篇
  2003年   1495篇
  2002年   1134篇
  2001年   898篇
  2000年   791篇
  1999年   557篇
  1998年   362篇
  1997年   319篇
  1996年   230篇
  1995年   211篇
  1994年   188篇
  1993年   101篇
  1992年   90篇
  1991年   86篇
  1990年   95篇
  1989年   66篇
  1988年   62篇
  1987年   41篇
  1986年   46篇
  1985年   23篇
  1984年   7篇
  1983年   7篇
  1982年   1篇
  1981年   3篇
  1980年   5篇
  1979年   4篇
  1970年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
机器视觉技术通过视觉采集和分析系统对外界环境进行实时图像采集和处理,得到目标的特征信息,最终实现外部设备的控制.机器视觉技术具有精度高、实时性强、自动化与智能化程度高的优点,已广泛应用于机器人控制、工业生产、辅助医疗诊断等领域.随着医疗技术的发展,机器视觉作为人工智能的重要分支,在康复领域也得到越来越多的应用.本文综述了机器视觉的基本结构和工作原理,并对其在辅助辅具、肢体康复、心理康复等5种康复领域的常见应用进展状况进行简要归纳与介绍,最后总结了机器视觉应用于康复领域的主要问题和发展趋势.  相似文献   
992.
目的 使用加权基因共表达网络分析探究糖尿病肾病基因的协同共表达,寻找糖尿病肾病发病的潜在关键基因.方法 从GEO数据库下载GSE30122表达谱数据,根据基因的相关性,构建基因共表达模块,并计算模块基因与疾病的相关性,选取与疾病显著相关的关键模块,使用R包clusterprofiler数据库进行GO与KEGG富集分析,并根据基因log FC值与富集最显著的通路关联并分析.结果 MEturquoise模块与疾病呈显著相关性(P=0.02);利用limma包筛选出的差异表达基因与关键模块中基因取交集,共得到201个共有关键基因,主要富集于细胞黏附分子、糖尿病并发症中的AGE-RAGE信号通路,细胞黏附分子中的CDH3、F11R、VTCN1表达下调,ITGA8、NECTIN2、NTNG1表达上调;AGE-RAGE信号通路中MAPK13表达上调,而COL4A3、PLCE1、PLCG2、VEGFA表达下调.结论 细胞黏附分子中的CDH3、F11R、VTCN1、ITGA8、NECTIN2、NTNG1等基因与AGE-RAGE信号通路中的MAPK13、COL4A3、PLCE1、PLCG2、VEGFA等基因可能在DN的发生发展中起到关键作用.  相似文献   
993.
994.
995.
996.
This study investigates the clinical and imaging characteristics of coronavirus disease 2019 (COVID‐19) patients with false‐negative nucleic acids. Mild‐to‐moderate COVID‐19 patients, including 19 cases of nucleic acid false‐negative patients and 31 cases of nucleic acid positive patients, were enrolled. Their epidemiological, clinical, and laboratory examination data and imaging characteristics were analyzed. Risk factors for false negatives were discussed. Compared with the nucleic acid positive group, the false‐negative group had less epidemiological exposure (52.6% vs 83.9%; P = .025), less chest discomfort (5.3% vs 32.3%; P = .035), and faster recovery (10 [8, 13] vs 15 [11, 18.5] days; P = .005). The number of involved lung lobes was (2 [1, 2.5] vs 3 [2, 4] days; P = .004), and the lung damage severity score was (3 [2.5, 4.5] vs 5 [4, 9] days; P = .007), which was lighter in the nucleic acid false‐negative group. Thus, the absence of epidemiological exposure may be a potential risk factor for false‐negative nucleic acids. The false‐negative cases of COVID‐19 are worth noting because they have a risk of viral transmission without positive test results, lighter clinical manifestations, and less history of epidemiological exposure.  相似文献   
997.
Asthma is a chronic respiratory disease characterized by airway inflammation and remodeling as well as hyper-responsiveness. Thymic stromal lymphopoietin (TSLP), which is a crucial inflammatory cytokine in immune homeostasis, consists of two isoforms, the long isoform lfTSLP and short isoform sfTSLP. The lfTSLP promotes inflammation and plays a pivotal role in asthma pathogenesis, while sfTSLP had been reported to have anti-asthma effects. Experiments have shown that lfTSLP could induce autophagy in hepatocytes. It is unknown whether lfTSLP or sfTSLP could influence autophagy and affect the progression of asthma. Using house dust mite (HDM)-stimulated airway smooth muscle cells as an in vitro model and HDM-induced asthma mice as in vivo model, we found that lfTSLP could induce autophagy and remodeling, while sfTSLP has the reverse effect. Strikingly, sfTSLP treatment in vivo reversed HDM-mediated activation of inflammation and airway remodeling, partly determined by autophagy change. These findings may help us understand the function of TSLP isoforms in the pathogenesis of asthma, and they support the use of drugs targeting sfTSLP and TSLP for asthma treatment.  相似文献   
998.
The species of Beauveria bassiana is widely used for the management of agricultural insect pests. In this study, we integrated egfp-double-stranded RNA (dsRNA) to a previously generated egfp-expressing B. bassiana transformant (Bb-egfp#3) using a protoplast integration method. The Bb-egfp#3 protoplast was mixed with the dsRNA under PEG/CaCl2 conditions and liquid-cultured in Sabouraud dextrose broth for 5 days. A control culture followed the same procedure without dsRNA. Bb-egfp#3/egfp-dsRNA cultures showed very low fungal growth (OD630 = 0.2) compared to the control culture, Bb-egfp#3 only (OD630 = 1.1). Screening of possible transformants on Sabouraud dextrose agar revealed a transformant T3, without egfp signal. T3 was confirmed as B. bassiana through sequencing of conserved genes and insect bioassays. Interestingly, the genomic egfp fragment of T3 was disrupted, and the egfp signal was not detected over four subcultures, which was also confirmed by RNA-seq of Bb-egfp#3 and T3. This study provides an interesting observation that protoplast integration with dsRNA could possibly generate significantly reduced gene expression in B. bassiana and it is stable across several generations.  相似文献   
999.
Li  Yu-Yang  Cai  Qing  Li  Bao-Sheng  Qiao  Shu-Wei  Jiang  Jia-Yang  Wang  Dan  Du  Xue-Chun  Meng  Wei-Yan 《Inflammation》2021,44(3):846-858
Inflammation - Periodontitis is a chronic inflammatory disease induced by Porphyromonas gingivalis (P. gingivalis) and other pathogens. P. gingivalis release various virulence factors including...  相似文献   
1000.
Objective: The study was designed to investigate some plasma markers which help us to decide the use of adjuvant corticosteroid therapy in bronchopulmonary dysplasia (BPD) of premature infants.Methods: Thirty BPD infants were treated by dexamethasone. Among these cases, dexamethasone was significant effective in 10 cases, and no significant effective in 20 cases. These patients were divided into two groups as the significant effect (SE) group (n=10) and the non-significant effect (NE) group (n=20) according to the curative effect of dexamethasone. Fifteen non-BPD infants with gestational age and gender matching were selected as the control group. Plasma samples before and after dexamethasone treatment were collected from three infants chosen randomly from SEG for the data-independent acquisition (DIA) analysis. ELISA was further used to detect the levels of differential proteins LRP1 and S100A8 in all individuals, including SE, NE and control groups.Results: DIA analysis results showed that after dexamethasone treatment, there were a total of 52 plasma proteins that showed significant differences, of which 43 proteins were down-regulated and 9 proteins were up-regulated. LRP1 and S100A8 were two plasma proteins that were significantly changed after dexamethasone treatment. Compared with the control group, plasma LRP1 was significantly increased in BPD. Interestingly, the plasma concentration of LRP1 in the NE group was significantly higher than that in the SE group. S100A8, as an indicator of plasma inflammation, was significantly higher in BPD than the control group. Unlike LRP1, there was no significantly difference between the SE and NE group (P=0.279) before dexamethasone treatment.Conclusion: Elevated plasma LRP1 and S100A8 in BPD infants are two indicators that correlated with the efficacy of dexamethasone, and might be used as biomarkers for deciding the use of adjuvant corticosteroids therapy in the BPD.  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