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   5869篇
  免费   508篇
  国内免费   322篇
耳鼻咽喉   8篇
儿科学   63篇
妇产科学   373篇
基础医学   442篇
口腔科学   78篇
临床医学   599篇
内科学   434篇
皮肤病学   39篇
神经病学   158篇
特种医学   435篇
外国民族医学   4篇
外科学   307篇
综合类   1260篇
预防医学   386篇
眼科学   30篇
药学   642篇
  2篇
中国医学   611篇
肿瘤学   828篇
  2024年   10篇
  2023年   62篇
  2022年   137篇
  2021年   221篇
  2020年   173篇
  2019年   180篇
  2018年   169篇
  2017年   220篇
  2016年   266篇
  2015年   225篇
  2014年   405篇
  2013年   412篇
  2012年   425篇
  2011年   488篇
  2010年   410篇
  2009年   359篇
  2008年   313篇
  2007年   328篇
  2006年   283篇
  2005年   236篇
  2004年   180篇
  2003年   150篇
  2002年   151篇
  2001年   96篇
  2000年   91篇
  1999年   51篇
  1998年   44篇
  1997年   57篇
  1996年   54篇
  1995年   34篇
  1994年   44篇
  1993年   39篇
  1992年   35篇
  1991年   28篇
  1990年   27篇
  1989年   24篇
  1988年   27篇
  1987年   22篇
  1986年   19篇
  1985年   31篇
  1984年   25篇
  1982年   16篇
  1981年   11篇
  1980年   17篇
  1979年   14篇
  1978年   14篇
  1977年   11篇
  1976年   12篇
  1974年   15篇
  1973年   13篇
排序方式: 共有6699条查询结果,搜索用时 15 毫秒
41.
The only effective measure to decrease morbidity and mortality caused by the influenza virus in the human population is worldwide vaccination. Vaccination produces neutralizing antibodies that target the HA1 subunit of the HA (hemagglutinin) protein and are strain specific. The effectiveness of new influenza vaccines are linked to two factors, the correct prediction of the circulating strains in the population in a particular season and the concentration of the HA1 protein in the vaccine formulation. With the advent of the licensing of quadrivalent vaccines, pharmaceutical manufacturers are under considerable pressure due to time constraints and dedicated resources to deliver 194–198 million doses (2020–2021 U.S. market) of vaccine. Considering the valuable resources needed to produce the influenza vaccine in a timely manner, the efficient quantitation of the HA1 protein (the main component in the influenza vaccine) is required. Currently the only method approved by regulatory agencies for quantitation of the HA antigen in vaccines is the single radial immunodiffusion assay (SRID), an antibody dependent assay that is not time efficient. Time efficient methods that are antibody independent e.g. reverse phase-high performance liquid chromatography (RP-HPLC) or size exclusion-HPLC (SE-HPLC) are available. An improved method implementing reverse phase-ultra performance liquid chromatography (RP-UPLC) has been developed to quantitate the HA1 protein antigen present in the high yield reassortant vaccine seed viruses from influenza A H1N1 and H3N2 subtypes harvested from inoculated embryonated chicken eggs. This method differentiates between high yield and lower yielding reassortants in order to select the best vaccine candidate seed virus with the highest growth ‘in ovo’. This direct capability to monitor the HA1 concentration of potential reassortant seed viruses and to choose the best yielding HA influenza reassortant when faced with multiple viral seed candidates provides a major advantage on the industrial scale to the influenza vaccine process.  相似文献   
42.
43.
软骨种子细胞的老化和缺乏是限制软骨组织工程在临床应用的瓶颈问题。本文概述了目前对软骨种子细胞研究的两个方面 :扩大种子细胞的来源及预防和延缓种子细胞功能老化 ,并展望软骨组织工程在监床的应用前景。  相似文献   
44.
为探讨B超与放射免疫分析诊断卵巢癌的临床价值 ,对 45例卵巢癌患者行B超及放射免疫分析血液CEA、CA12 5、TSGF。提示B超与CA12 5、TSGF ,CEA联合检查 ,可提高对卵巢癌的诊断率  相似文献   
45.
对 30 2例胃癌术前检测CA5 0、CA199、CA12 5、CA72 4、CEA、β2 -MG、SA、Fer等 8种肿瘤标志物 ,并按年龄、胃癌病期及病理分类分组分析。结果 :(1) 30 2例胃癌血清中 8种肿瘤标志物总的阳性率依次为 β2 -MG6 5 .9%、CA19932 .1%、CA72 42 9.5 %、SA2 4.5 %、CA12 5 16 .9%、CEA13 .2 %、CA5 0 11.6 %、Fer(- )。 (2 ) 8种肿瘤标志物阳性率与年龄大小均无关。 (3) β2 -MG、CA72 4、CA12 5、CA199、SA、CEA、在Ⅲ、Ⅳ期病例中均较敏感 ,且随病期增加 ,阳性率增高。 (4 )CA199和CA72 4对腺癌、β2 -MG和SA对低分化腺癌、β2 -MG和CA72 4对粘液癌、混合型癌阳性率较高。提示血清测β2 -MG、CA199、CA72 4、SA、CA12 5对胃癌的辅助诊断有一定应用价值  相似文献   
46.
子宫腺肌病误诊原因分析及术前诊断临床探讨   总被引:5,自引:0,他引:5  
段社教  申延琴 《河北医学》2000,6(9):790-792
目的;探讨子宫腺肌病误诊原因及近年术前诊断研究进展,方法;对我院近10年收治的197例腺肌病患者的临床资料进行回顾性分析。结果:1990年元月至1997年12月128例腺肌病患者术前,术后诊断符合率仅为29.7%,术后误诊,漏诊率达70.3%,1998年元月至1999年12月69例术前经测定血清CA125及 腔双氧水造影后误诊,漏诊率降为27.5%术前主要误诊为子宫肌瘤或(和)子宫内膜异位症,结论  相似文献   
47.
子宫内膜异位症癌抗原(CA125)检测及其临床意义   总被引:3,自引:0,他引:3  
目的:探讨子宫内膜异位症与CA125有无相关性、提高临床子宫内膜异位症诊断雍诊断最佳途径。方法:用放射免疫测定法(RIA)检测79例子宫内膜异位症、70例子宫肌瘤、64例子宫颈癌、80名正常育龄女性为对照。结果:子宫内膜异位症、子宫肌瘤、子宫颈癌、正常对照组阳性率分别是79.75%、8.57%、17.19%、0.00%。前者显著高于后三者(P〈0.01)。结论:CA125检测为临床诊断子宫内膜异位  相似文献   
48.
Venous volume (venous capacity) of the calf is low in patientswith acute myocardial infarction, who also have a high riskof deep vein thrombosis (DVT). The effect of graduated compressionstockings on the venous volume and on the incidence of DVT wastherefore studied in 80 patients aged 70 years and above withacute myocardial infarction. Graduated compression stockingswere randomly fitted to one leg, the other serving as a control,after which the venous volume was measured by strain gauge plethysmography.The incidence of DVT was measured by the 125I fibrinogen uptaketest. Venous volume was significantly higher in legs treatedwith graduated compression stockings compared to control legs.DVT developed in eight control legs but not in any leg treatedwith graduated compression stockings (P = 0.003). DVT was alsosignificantly more frequent in women compared to men and themajority of DVT developed in legs with very low venous volumevalues.  相似文献   
49.
To test iodine-125 labelled low-density lipoprotein (125I-LDL), polyclonal indium-111 labelled immunoglobulin G (111In-IgG) and iodine-125 labelled endothelin-1 uptake in metabolically active atheromatous plaques after arterial wall injury, we performed balloon de-endothelialization of carotid arteries or abdominal aortas in 24 New Zealand male rabbits which were fed with a normal diet (n=14) or a hypercholesterolaemic diet (n=10) after surgery. Six weeks later the animals were injected with 200 Ci of (125I-LDL), and/or with 100 Ci of 111In-IgG or with 9 Ci of 125I-endothelin-1. Forty-eight hours later the animals were sacrificed. Carotid arteries and aortas were removed, counted and fixed for autoradiography and light microscopy examination. Contralateral carotid arteries and thoracic aortas served as controls.Significant 111In-IgG uptake was observed in the injured arteries at autoradiography, with localization mainly in the healing edges, and at well counting. The percentage of the injected dose per gram (%D.inj/g) was 0.0188±0.06 versus 0.0059±0.003 in controls (P< 0.05). There was no difference in 111In-IgG uptake between arteries with injury alone and those with active atheroma formation at the site of the injury. Significant (125I-LDL), uptake was observed only when lipid deposition was present at light microscopy (%D.inj/g of 0.0024±0.0005 vs 0.0010±0.0003 in controls, P < 0.05). 125I-endothelin-1 accumulation was observed in four of five injured aortas both at autoradiography, with diffuse localization, and at well counting (%D.inj/g of 0.0012±0.0004 in the abdominal aortas vs 0.0008±0.0003 in the thoracic aortas).Polyclonal IgG may accumulate in injured arteries without active atheroma formation. Inflammatory reaction at the site of the injury may cause 111In-IgG uptake independently of atheromatous plaque formation. LDL accumulation takes place only with active atheroma formation at the site of the injury. Use of labelled peptides such as endothelin-1 may provide further insight into the mechanisms of atheromatous plaque formation.  相似文献   
50.
Summary N6-p-Hydroxyphenylisopropyladenosine (HPIA) has been labelled with carrier-free Na[125I] to very high specific activity (2,175 Ci/mmol) and used as an agonist ligand to characterize Ri adenosine receptors in rat cerebral cortex membranes. The binding is saturable, reversible, stereospecific and dependent on protein concentration. The specific binding at 37°C was of high affinity with an equilibrium dissociation constant KD of 0.48 nmol/l and was saturable with 0.23 pmol of [125I]HPIA per mg of protein. The rate constant of association, k1, was 3.25×108 l mol–1 min–1 and that of dissociation, k2, 0.0110 min–1 yielding a t1/2 of 63 min. In competition experiments the (–)isomer of N6-phenylisopropyladenosine (PIA) was 16-fold more potent than the (+)isomer in competing for the binding sites. Specific binding was most effectively displaced by N6-cyclohexyladenosine (CHA, ki=0.26 nmol/l), (–)PIA (ki=0.33 nmol/l) and HPIA (ki=0.52 nmol/l), whereas 5-N-ethylcarboxamidoadenosine (NECA, ki-1.42 nmol/l) was less effective. The methylxanthines 3-isobutyl-1-methylxanthine (IBMX), theophylline and caffeine which have been classified as adenosine antagonists had ki values between 5–34 mol/l. Binding of [125I]HPIA was regulated by guanine nucleotides and divalent cations. The results indicate that [125I]HPIA labels Ri adenosine receptors in rat brain membranes.  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