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   72072篇
  免费   6163篇
  国内免费   4491篇
耳鼻咽喉   449篇
儿科学   1933篇
妇产科学   943篇
基础医学   13876篇
口腔科学   1448篇
临床医学   6037篇
内科学   10847篇
皮肤病学   1220篇
神经病学   4518篇
特种医学   1430篇
外国民族医学   29篇
外科学   5054篇
综合类   14271篇
现状与发展   23篇
一般理论   1篇
预防医学   3873篇
眼科学   1203篇
药学   5555篇
  7篇
中国医学   1735篇
肿瘤学   8274篇
  2024年   49篇
  2023年   748篇
  2022年   1143篇
  2021年   2089篇
  2020年   1970篇
  2019年   2176篇
  2018年   1953篇
  2017年   2095篇
  2016年   2324篇
  2015年   2442篇
  2014年   3739篇
  2013年   4775篇
  2012年   3882篇
  2011年   4897篇
  2010年   3982篇
  2009年   4052篇
  2008年   4202篇
  2007年   4606篇
  2006年   4434篇
  2005年   4067篇
  2004年   3685篇
  2003年   3175篇
  2002年   2711篇
  2001年   2418篇
  2000年   2043篇
  1999年   1635篇
  1998年   1304篇
  1997年   1053篇
  1996年   766篇
  1995年   777篇
  1994年   587篇
  1993年   389篇
  1992年   295篇
  1991年   239篇
  1990年   199篇
  1989年   131篇
  1988年   101篇
  1987年   79篇
  1986年   62篇
  1985年   191篇
  1984年   208篇
  1983年   150篇
  1982年   195篇
  1981年   156篇
  1980年   117篇
  1979年   126篇
  1978年   76篇
  1977年   57篇
  1976年   48篇
  1975年   55篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
71.
Job stress and the Circadian Locomotor Output Cycles Kaput (CLOCK) gene could affect circadian rhythm and sleep quality. The main aim of our present study was to investigate the association of job stress, CLOCK gene polymorphism and their interaction with sleep quality in a non‐clinical Chinese Han population, which has not been reported to date. Using a cross‐sectional design, 450 subjects were recruited in Beijing. Sleep quality was measured with the Pittsburgh Sleep Quality Index (PSQI) and job stress was measured with the Work Stress Scale. CLOCK gene rs11932595 polymorphism was genotyped in 297 blood samples. Correlation analysis showed a close but different association of high job stress with the PSQI and its components. Analysis of variance showed significant main effects of the CLOCK gene rs11932595 polymorphism. G‐allele carriers had a higher score in the PSQI, sleep duration, sleep latency and sleep disturbances. Further interaction analyses showed an ordinal interaction on sleep duration, and a disordinal interaction on daytime dysfunction. Specifically, G‐allele carriers had poorer sleep duration than AA homozygotes when in high job stress, while the two subgroups displayed similar sleep duration when in low job stress, conforming to the diathesis–stress model. In comparison to G‐allele carriers, AA homozygotes experienced less daytime dysfunction when in low job stress whereas more daytime dysfunction when in high job stress, fitting with the differential susceptibility model. As genetic links have been revealed, our investigation might be conducive for elucidating aetiological factors for sleep quality and targets for implementing interventions to attain good sleep quality.  相似文献   
72.
73.
目的对1例临床拟诊为X-连锁高IgM综合征(X-linked hyper-IgM syndrome,XHIM)并发进行性多灶性脑白质病变(progressive multifocal leukoencephalopathy,PML)的患儿CD40L基因及人类嗜神经多瘤病毒(Jamestown Canyon virus,JCV)进行检测,明确致病原因,为临床诊断提供依据。方法采集患儿及父母外周血提取基因组NDA,设计扩增CD40L基因5个外显子及外显子-内含子连接区的特异性引物并进行PCR扩增,产物测序结果与GenBank中CD40L基因序列分析对比确定有无变异。用两对JCV特异性引物对患儿外周血DNA行巢式PCR扩增,目的条带PCR产物测序结果与GenBank中JCV序列对比确定患儿是否存在JCV感染。结果测序结果显示患儿为CD40L c.506 A>C(p.Tyr169Ser)错义变异半合子,该变异位于CD40L肿瘤坏死因子同源区结构域,引起CD40L蛋白疏水作用及结构稳定性丧失,经PolyPhen2及SIFT蛋白功能预测软件预测分别为很可能有害变异(probably damaging,score=1.00)及有害变异(deleterious,score=-8.868),该变异尚未见文献报道。患儿母亲携带CD40L c.506 A>C(p.Tyr169Ser)半合子变异,父亲未检测到该变异。患儿外周血DNA巢式PCR产物经凝胶电泳后发现JCV目的条带,测序结果与GenBank中JCV基因序列比对同源性达到99%,表明患儿外周血DNA中含有JCV,有JCV感染。结论CD40L基因分析及JCV检测结果确诊患儿为XHIGM,其并发的PML与JCV感染有关。  相似文献   
74.
The hormone 20-hydroxyecdysone is fundamental for regulating moulting and metamorphosis in immature insects, and it plays a role in physiological regulation in adult insects. This hormone acts by binding and activating a receptor, the ecdysone receptor, which is part of the nuclear receptor gene superfamily. Here, we analyse the genome of the kissing bug Rhodnius prolixus to annotate the nuclear receptor superfamily genes. The R. prolixus genome displays a possible duplication of the HNF4 gene. All the analysed insect organs express most nuclear receptor genes as shown by RT-PCR. The quantitative PCR analysis showed that the RpEcR and RpUSP genes are highly expressed in the testis, while the RpHNF4-1 and RpHNF4-2 genes are more active in the fat body and ovaries and in the anterior midgut, respectively. Feeding does not induce detectable changes in the expression of these genes in the fat body. However, the expression of the RpHNF4-2 gene is always higher than that of RpHNF4-1. Treating adult females with 20-hydroxyecdysone increased the amount of triacylglycerol stored in the fat bodies by increasing their lipogenic capacity. These results indicate that 20-hydroxyecdysone acts on the lipid metabolism of adult insects, although the underlying mechanism is not clear.  相似文献   
75.
76.
Discoid lupus erythematosus (DLE) is the most common skin manifestation of lupus; however, the molecular mechanisms underlying DLE remain unknown. Therefore, we aimed to identify key differentially expressed genes (DEGs) in discoid lupus skin and investigate their potential pathways.To identify candidate genes involved in the occurrence and development of the disease, we downloaded the microarray datasets GSE52471 and GSE72535 from the Gene Expression Database (GEO). DEGs between discoid lupus skin and normal controls were selected using the GEO2R tool and Venn diagram software (http://bioinformatics.psb.ugent.be/webtools/Venn/). The Database for Annotation, Visualization, and Integrated Discovery (DAVID), Enrichr, and Cytoscape ClueGo were used to analyze the Kyoto Encyclopedia of Gene and Genome pathways and gene ontology. Protein-protein interactions (PPIs) of these DEGs were further assessed using the Search Tool for the Retrieval Interacting Genes version 10.0.Seventy three DEGs were co-expressed in both datasets. DEGs were predominantly upregulated in receptor signaling pathways of the immune response. In the PPI network, 69 upregulated genes were selected. Furthermore, 4 genes (CXCL10, ISG15, IFIH1, and IRF7) were found to be significantly upregulated in the RIG-I-like receptor signaling pathway, from analysis of Enrichr and Cytoscape ClueGo.The results of this study may provide new insights into the potential molecular mechanisms of DLE. However, further experimentation is required to confirm these findings.  相似文献   
77.
目的:探讨弥漫大B细胞淋巴瘤(DLBCL)患者外周血中白细胞介素6(IL-6)、白细胞介素8(IL-8)和白细胞介素10(IL-10)的表达及其临床意义。方法:回顾性分析2018年3月至2021年3月厦门大学附属第一医院78例初治DLBCL患者的临床资料,选取同期58名健康体检者作为健康对照。采用流式微球捕获芯片技术(CBA)检测受试者外周血中IL-6、IL-8和IL-10表达水平,并分析DLBCL患者这些指标与临床特征、疾病分期和预后的关系。结果:DLBCL组IL-6、IL-8和IL-10表达水平均高于健康对照组[(171.81±70.91)pg/ml比(2.71±0.28)pg/ml,(47.95±13.04)pg/ml比(3.69±0.47)pg/ml,(38.02±10.35)pg/ml比(1.77±0.23)pg/ml],差异均有统计学意义( t值分别为2.38、3.39、3.50,均 P<0.05)。DLBCL患者中,骨髓侵犯、国际预后指数(IPI)评分3~5分及临床分期Ⅲ~Ⅳ期患者的IL-6、IL-8和IL-10水平均高于骨髓未侵犯、IPI评分1~2分及临床分期Ⅰ~Ⅱ期患者(均 P<0.05)。DLBCL患者外周血中IL-6与IL-8、IL-6与IL-10、IL-8与IL-10表达水平均相关( r2值分别为0.93、0.89、0.89,均 P<0.05)。IL-6、IL-8、IL-10均高表达的患者中,临床分期为Ⅲ~Ⅳ期、6个疗程后未缓解患者比例均高于IL-6、IL-8、IL-10单项及两项高表达患者,差异均有统计学意义(均 P<0.05)。 结论:DLBCL患者外周血清中IL-6、IL-8和IL-10表达水平具有较高的相关性,三者表达水平升高预示DLBCL患者疾病分期较晚、预后较差。  相似文献   
78.
79.
目的探讨细胞增殖抑制基因(HSG)、增殖细胞核抗原(Ki67)组织表达与宫颈癌新辅助化疗治疗效果的相关性。方法选取2017年1月至2019年7月广东省第二人民医院收治的180例经临床确诊的宫颈癌患者作为研究对象,采用随机数字表法分为观察组和对照组,每组90例。对照组采用传统手术治疗和放疗;观察组实施收治治疗、放疗及新辅助化疗。统计比较两组治疗前后HSG、Ki67水平变化、临床疗效及不良反应发生率情况。结果观察组术后3周及术后6周HSG阳性表达率高于对照组,而Ki67阳性表达率低于对照组(P<0.05)。观察组疾病控制率(DCR)高于对照组(P<0.05)。结论宫颈患部HSG表达率与宫颈癌患者的康复情况呈正相关,而Ki67表达水平与宫颈癌患者DCR呈负相关。评估HSG及Ki67指标变化对宫颈癌新辅助化疗结果的评价具有重要的指导价值。  相似文献   
80.
《Vaccine》2021,39(38):5401-5409
BackgroundPapua New Guinea (PNG) introduced the 13-valent pneumococcal conjugate vaccine (PCV13) in 2014, with administration at 1, 2, and 3 months of age. PCV13 has reduced or eliminated carriage of vaccine types in populations with low pneumococcal carriage prevalence, carriage density and serotype diversity. This study investigated PCV13 impact on serotype-specific pneumococcal carriage prevalence, density, and serotype diversity in PNG infants, who have some of the highest reported rates of pneumococcal carriage and disease in the world.MethodsNasopharyngeal swabs were collected at 1, 4 and 9 months of age from PCV13-vaccinated infants (n = 57) and age-/season-matched, unvaccinated infants (at approximately 1 month, n = 53; 4 months, n = 57; 9 months, n = 52). Serotype-specific pneumococcal carriage density and antimicrobial resistance genes were identified by qPCR and microarray.ResultsPneumococci were present in 89% of swabs, with 60 different serotypes and four non-encapsulated variants detected. Multiple serotype carriage was common (47% of swabs). Vaccine type carriage prevalence was similar between PCV13-vaccinated and unvaccinated infants at 4 and 9 months of age. The prevalence of non-vaccine type carriage was also similar between cohorts, with non-vaccine types present in three-quarters of samples (from both vaccinated and unvaccinated infants) by 4 months of age. The median pneumococcal carriage density was high and similar at each age group (~7.0 log10 genome equivalents/mL). PCV13 had no effect on overall pneumococcal carriage density, vaccine type density, non-vaccine type density, or the prevalence of antimicrobial resistance genes.ConclusionPNG infants experience dense and diverse pneumococcal colonisation with concurrent serotypes from 1 month of age. PCV13 had no impact on pneumococcal carriage density, even for vaccine serotypes. The low prevalence of vaccine serotypes, high pneumococcal carriage density and abundance of non-vaccine serotypes likely contribute to the lack of PCV13 impact on carriage in PNG infants. Indirect effects of the infant PCV programs are likely to be limited in PNG. Alternative vaccines with broader coverage should be considered.  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