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   963篇
  免费   51篇
  国内免费   46篇
耳鼻咽喉   7篇
儿科学   3篇
妇产科学   5篇
基础医学   113篇
口腔科学   6篇
临床医学   77篇
内科学   117篇
皮肤病学   6篇
神经病学   32篇
特种医学   5篇
外科学   24篇
综合类   126篇
预防医学   88篇
眼科学   2篇
药学   366篇
中国医学   48篇
肿瘤学   35篇
  2023年   11篇
  2022年   13篇
  2021年   22篇
  2020年   17篇
  2019年   17篇
  2018年   22篇
  2017年   25篇
  2016年   35篇
  2015年   22篇
  2014年   43篇
  2013年   77篇
  2012年   61篇
  2011年   76篇
  2010年   50篇
  2009年   46篇
  2008年   45篇
  2007年   64篇
  2006年   49篇
  2005年   53篇
  2004年   32篇
  2003年   50篇
  2002年   30篇
  2001年   19篇
  2000年   17篇
  1999年   20篇
  1998年   11篇
  1997年   7篇
  1996年   20篇
  1995年   16篇
  1994年   5篇
  1993年   7篇
  1992年   7篇
  1991年   8篇
  1990年   6篇
  1989年   5篇
  1988年   6篇
  1987年   7篇
  1986年   3篇
  1985年   4篇
  1984年   3篇
  1983年   8篇
  1982年   2篇
  1981年   2篇
  1980年   2篇
  1974年   2篇
  1973年   3篇
  1971年   1篇
  1970年   1篇
  1969年   2篇
  1968年   1篇
排序方式: 共有1060条查询结果,搜索用时 31 毫秒
1.
《Vaccine》2022,40(11):1594-1605
In addition to providing pathogen-specific immunity, vaccines can also confer nonspecific effects (NSEs) on mortality and morbidity unrelated to the targeted disease. Immunisation with live vaccines, such as the BCG vaccine, has generally been associated with significantly reduced all-cause infant mortality. In contrast, some inactivated vaccines, such as the diphtheria, tetanus, whole-cell pertussis (DTPw) vaccine, have been controversially associated with increased all-cause mortality especially in female infants in high-mortality settings. The NSEs associated with BCG have been attributed, in part, to the induction of trained immunity, an epigenetic and metabolic reprograming of innate immune cells, increasing their responsiveness to subsequent microbial encounters. Whether non-live vaccines such as DTPw induce trained immunity is currently poorly understood. Here, we report that immunisation of mice with DTPw induced a unique program of trained immunity in comparison to BCG immunised mice. Altered monocyte and DC cytokine responses were evident in DTPw immunised mice even months after vaccination. Furthermore, splenic cDCs from DTPw immunised mice had altered chromatin accessibility at loci involved in immunity and metabolism, suggesting that these changes were epigenetically mediated. Interestingly, changing the order in which the BCG and DTPw vaccines were co-administered to mice altered subsequent trained immune responses. Given these differences in trained immunity, we also assessed whether administration of these vaccines altered susceptibility to sepsis in two different mouse models. Immunisation with either BCG or a DTPw-containing vaccine prior to the induction of sepsis did not significantly alter survival. Further studies are now needed to more fully investigate the potential consequences of DTPw induced trained immunity in different contexts and to assess whether other non-live vaccines also induce similar changes.  相似文献   
2.
《Vaccine》2021,39(45):6601-6613
AKS-452 is a biologically-engineered vaccine comprising an Fc fusion protein of the SARS-CoV-2 viral spike protein receptor binding domain antigen (Ag) and human IgG1 Fc (SP/RBD-Fc) in clinical development for the induction and augmentation of neutralizing IgG titers against SARS-CoV-2 viral infection to address the COVID-19 pandemic. The Fc moiety is designed to enhance immunogenicity by increasing uptake via Fc-receptors (FcγR) on Ag-presenting cells (APCs) and prolonging exposure due to neonatal Fc receptor (FcRn) recycling. AKS-452 induced approximately 20-fold greater neutralizing IgG titers in mice relative to those induced by SP/RBD without the Fc moiety and induced comparable long-term neutralizing titers with a single dose vs. two doses. To further enhance immunogenicity, AKS-452 was evaluated in formulations containing a panel of adjuvants in which the water-in-oil adjuvant, Montanide™ ISA 720, enhanced neutralizing IgG titers by approximately 7-fold after one and two doses in mice, including the neutralization of live SARS-CoV-2 virus infection of VERO-E6 cells. Furthermore, ISA 720-adjuvanted AKS-452 was immunogenic in rabbits and non-human primates (NHPs) and protected from infection and clinical symptoms with live SARS-CoV-2 virus in NHPs (USA-WA1/2020 viral strain) and the K18 human ACE2-trangenic (K18-huACE2-Tg) mouse (South African B.1.351 viral variant). These preclinical studies support the initiation of Phase I clinical studies with adjuvanted AKS-452 with the expectation that this room-temperature stable, Fc-fusion subunit vaccine can be rapidly and inexpensively manufactured to provide billions of doses per year especially in regions where the cold-chain is difficult to maintain.  相似文献   
3.
4.
用ELISA、IFA和IIP试验检测11例旋毛虫病人血清特异性抗体,阳性率分别为72.72%、81.82%和81.82%。它们之间无统计学差异,3项试验结果间存在良好一致性。 同时检测了30份健康献血员血清和20例其他寄生虫病人血清(包括华支睾吸虫病、四川肺吸虫病、日本血吸虫病、包虫病和阿米巴肝脓肿),旋毛虫病人组的ELISA、IFA和IIP阳性率明显为高。 由于3项免疫学试验均具有较好的特异性和灵敏性,故可以单独或联合用于人体旋毛虫病的诊断和流行病学调查。  相似文献   
5.
目的探讨脊髓血管畸形是否存在血管内皮生长因子(VEGF)表达,及其表达与临床特征之间是否存在相关性。方法在手术中留取56例脊髓血管畸形的脑脊液标本,其中动静脉畸形(SCAVM)23例,硬脊膜动静脉瘘(SDAVF)19例,海绵状血管瘤(CM)14例;以我院12例蛛网膜下腔阻滞病人脑脊液作为对照组,分别通过酶联免疫吸附方法(ELISA)测定脊髓血管畸形脑脊液中VEGF含量。结果SCAVM脑脊液中VEGF浓度为(277±66)pg/ml、SDAVF为(318±54)pg/ml、CM为(146±32)pg/ml均高于正常对照组(123±27)pg/ml。术前栓塞和出血均可导致脑脊液VEGF升高。结论VEGF与脊髓血管畸形的发生、发展存在一定关系,出血和栓塞均可影响VEGF的表达。  相似文献   
6.
两种清除法测定低密度脂蛋白胆固醇的临床评价   总被引:1,自引:0,他引:1  
目的对表面活性剂清除法 (SUR法 )和过氧化氢酶清除法 (CAT法 )两种低密度脂蛋白胆固醇 (LDL C)均相测定法进行临床评价。方法将上述两种方法与聚乙烯硫酸沉淀法 (PVS法 )进行比较 ,分析各自方法的精密度、准确性、特异性和干扰因素。结果两种清除法与PVS法 (X)具有良好的相关性 ,SUR法 (Y1) :Y1=0 .9311X +0 .10 2 2 ,r =0 .980 1;CAT法 (Y2 ) :Y2 =0 .94 0 1X +0 .0 991,r=0 .9832。高、中、低三种LDL C浓度混合血清所测定结果表明两种方法均具有良好的精密度 ,总CV值SUR法 3.4 5 - 3.89% ,CAT法 3.5 1- 3.99% ,均达到临床满意的程度。两法线性范围均较宽 (线性均至 8.2 2mmol/L) ,最低检测浓度均为 0 .12mmol/L ,平均回收率SUR法为 98.0 % ,CAT法为 97.6 %。TG <14 .2mmol/L ,Hb <5g/L ,HDL C <3.88mmol/L ,胆红素 <4 5 0 μmol/L对两法基本无影响。 结论两种LDL C清除法测定结果的准确度和精密度均符合临床要求 ,适宜自动分析 ,值得在临床推广应用。  相似文献   
7.
周婷  杨军  潘景峰  陈志刚  张峰 《农垦医学》2002,24(6):399-401
目的 :应用荧光定量PCR方法精确检测HBV -DNA的拷贝数 ,为临床判断病毒复制程度提供指标 ;对比分析荧光定量PCR方法和ELISA方法检测HBV -DNA的结果。方法 :用荧光定量PCR法检测 10 14例用ELISA法诊断为乙型肝炎病人的血清HBV -DNA拷贝数。结果 :10 14例病人中 ,病毒拷贝数≥ 1× 10 5的 4 99例 ,阳性率4 9.2 % ;HBeAg阳性患者的HBV -DNA拷贝数≥ 1× 10 5的阳性率显著高于HBeAg阴性患者。结论 :荧光定量PCR检测HBV病毒复制情况结果准确 ,对临床工作指导意义更大 ;HBeAg是一项重要指标。  相似文献   
8.
本文介绍了人类精浆免疫抑制因子分离及免疫活性测定的全过程。通过低温高速离心,SephadexG-100凝胶过滤,DEAE离子交换层析等步骤从人精浆中分离出两种免疫抑制因子——DF_1和DF_2。DF_2达到聚丙烯酰胺凝胶电泳纯,呈单一蛋白带,DF_1呈二条蛋白带。二者对PHA诱导的人外周血淋巴细胞转化和人外周血NK细胞活性均有抑制作用。100μg/ml培养液的DF_1和DF_2对PHA诱导的淋转抑制率分别为41.7%和68.2%;对NK细胞活性的抑制率分别为30.4%和81.5%。在PHA诱导的淋转中同时加入DF_1和DF_2,抑制率为80.7%。比较不同浓度的DF_1,DF_2对PHA诱导的淋转抑制作用结果表明:100μg/ml具有相对高的抑制活性。不同浓度的DF_2对NK活性抑制作用也表现出类似结果。  相似文献   
9.
The GABA (gamma-aminobutyric acid) hypothesis of kindling suggests that the permanent changes caused by the kindling procedure result from a loss of GABA-mediated inhibition. Pharmacological studies have generally supported this hypothesis: GABA-complex antagonists accelerate (or stimulate) kindling, whereas GABA-complex agonists retard (or reverse) it. Assay studies, however, have presented an inconsistent picture. Earlier studies found no GABAergic brain changes after kindling, whereas recent studies have reported postkindling changes in a number of GABA-related parameters. The crucial difference seems to be that earlier studies assayed GABA parameters in "whole tissue," whereas recent studies have concentrated on "synaptic" GABA. As indicated by recent studies, when the "metabolic pool" is excluded, kindled subjects show a variety of persistent abnormalities in the GABA system. These data are generally consistent with the GABA hypothesis of kindling.  相似文献   
10.
Hepatitis B virus (HBV) is one of the major causative agents of chronic liver diseases in Korea. HBV has been classified into 8 genotypes by a divergence of >8% in the entire genomic sequence, and have distinct geographic distributions. There are limited data on the relevance between HBV genotypes and clinical outcomes in Korea. To investigate the clinical feature relating to HBV genotype in Korea, a total 120 serum samples with HBsAg (65 from Seoul and 55 from the other city in Korea) were obtained from each 30 chronic HBV carriers with asymptomatic carrier (ASC), chronic hepatitis (CH), liver cirrhosis (LC) and hepatocellular carcinoma (HCC). HBV genotype was determined by either enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies against genotype-specific epitopes in the preS2-region or the direct sequencing of small S gene. HBV genotypes were determined in 105 (87.5%) of 120 samples. HBV genotype C was identified in all HBV carriers with ASC, CH, LC, and HCC. Genotypes A, B, D, E, F and G were not detected in any of them. Genotype C HBV prevails predominantly among chronic carriers of the virus in Korea, irrespective of their clinical stages of liver disease and geographic origin.  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