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   101368篇
  免费   7562篇
  国内免费   3947篇
耳鼻咽喉   310篇
儿科学   1898篇
妇产科学   1274篇
基础医学   17175篇
口腔科学   1375篇
临床医学   7719篇
内科学   20888篇
皮肤病学   1518篇
神经病学   4688篇
特种医学   2072篇
外国民族医学   19篇
外科学   5859篇
综合类   14267篇
现状与发展   21篇
预防医学   7666篇
眼科学   815篇
药学   13823篇
  26篇
中国医学   5215篇
肿瘤学   6249篇
  2023年   1143篇
  2022年   2449篇
  2021年   3173篇
  2020年   3062篇
  2019年   3237篇
  2018年   3118篇
  2017年   3252篇
  2016年   3680篇
  2015年   3914篇
  2014年   6746篇
  2013年   7902篇
  2012年   7154篇
  2011年   7490篇
  2010年   5837篇
  2009年   5488篇
  2008年   5297篇
  2007年   4883篇
  2006年   4447篇
  2005年   3845篇
  2004年   3266篇
  2003年   2740篇
  2002年   2224篇
  2001年   1951篇
  2000年   1556篇
  1999年   1341篇
  1998年   1231篇
  1997年   1071篇
  1996年   885篇
  1995年   901篇
  1994年   772篇
  1993年   641篇
  1992年   575篇
  1991年   468篇
  1990年   469篇
  1989年   381篇
  1988年   330篇
  1987年   298篇
  1986年   239篇
  1985年   637篇
  1984年   723篇
  1983年   552篇
  1982年   593篇
  1981年   489篇
  1980年   441篇
  1979年   384篇
  1978年   298篇
  1977年   235篇
  1976年   257篇
  1975年   234篇
  1974年   205篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Prostaglandin E1 (PGE1) was used in renal transplant recipients with living related donors. The drug was given intravenously from day 1 to day 7 after transplantation at a dose of 40 µg/kg twice a day. A total of 45 patients were studied divided into two groups: 25 patients were treated with PGE1 (group B) and the remaining 20 patients did not receive the drug (group A). In group B, 24-h creatinine clearance (Ccr) was 66 ± 12.8 ml/min compared with 40.3 ± 13.4 ml/min in group A on the fifth postoperative day (P < 0.05). Urinary levels of N-acetyl-β-d -glucosaminidase (NAG) and serum levels of platelet factor 4 (PF4) in group B were significantly lower than in group A. On the fourth postoperative day, the urinary excretion of thromboxan B2 (TxB2) in group A was higher than in group B, but not significantly (5.1 ± 3.0 ng/day and 2.8 ± 1.1 ng/day, respectively). Acute rejection occurred in four patients in group B and in 10 patients (40%) in group A. The percentage of Leu2a-positive lymphocytes in group B was higher than in group A. We conclude that postoperative administration of PGE1 improves graft function in kidneys from living related donors.  相似文献   
102.
精子洗涤对精液中HBV DNA含量的影响   总被引:8,自引:0,他引:8  
目的:检查HBV感染者精液是否存在乙型肝炎病毒(HBV),探讨精子洗涤是否能去除其中的HBV DNA。方法:用实时荧光定量PCR(FQ-PCR)法检测57名血清HBsAg阳性患者精液中HBV DNA,采用Percoll非连续梯度离心及上游法分离其中21份精液,并对洗涤后标本进行HBV DNA检测。结果:62份精液标本中有15份HBV DNA阳性,阳性率为24.19%;21份用于洗涤的精液标本中有,有7份HBV DNA阳性,洗涤后仍有6份标本阳性。结论:部分HBV感染者精液具有传染性,精子洗涤不能完全去除精液中的乙肝病毒。将HBV感染者的精液用于人工授精或体外受精应慎重。  相似文献   
103.
用放免法检测乙型慢性活动性肝炎病人的红细胞c3b受体(KBCCR1).结果:病人RBCCR1明显低于献血员(P<0.05);抗-HBs特异性免疫复合物阳性病人RBCCR1明显低于阴性病人(P<0.01),与红细胞C3b受体花环试验检测结果一致。表明乙型慢性活动性肝炎病人RBCCR1数量减少,活性下降。其原因可能是特异性循环免疫复合物占据了RBCCR1空位,使CR1活性下降。  相似文献   
104.
Taurine has been proposed as an inhibitory neurotransmitter or neuromodulator in the vertebrate central nervous system. Within the spinal cord, taurine has been shown to have a direct inhibitory effect on spinal neurons and to have a selective antinociceptive effect on chemically induced nociception. Although sufficient data exists to suggest that taurine plays a neurotransmitter or neuromodulatory role in the spinal cord, it is not known whether this amino acid is present in axon terminals nor if this amino acid has a unique pattern of distribution within spinal tissue. To address these questions a monoclonal antibody against taurine was employed to localize taurine-like immunoreactivity in the dorsal horn of the rat spinal cord by using both light and electron microscopic techniques. Taurine-like immunoreactivity was most dense and most prominent in laminae I and II of the dorsal horn. A moderate amount of immunoreactivity was also present in laminae VIII and IX and X while the remaining laminae were only lightly stained. In laminae I and II taurine-like immunostaining was evident within neuronal cell bodies, dendrites, myelinated and unmyelinated axons, axon terminals, and astrocytes and their processes. Cell counts of these two laminae indicated that approximately 30% of neuronal perikarya at the C2 level, 52% of neuronal perikarya at the T6 level, and 18% of neuronal perikarya at the L2 level of the cord exhibited taurine-like immunoreactivity. With preembedding diaminobenzidine staining, approximately 20% of the axons examined in laminae I and II were found to be immunoreactive for taurine. Using postembedding immunogold staining in combination with quantitative procedures, the highest densities of gold particles were found in axon terminals containing pleomorphic vesicles and forming symmetrical synapses (36.8 particles/micron2), in a subpopulation of myelinated axons (34.2 particles/micron2), in a subpopulation of neuronal dendrites (32.6 particles/micron2), and in capillary endothelial cells (39.8 particles/micron2). Moderate labeling occurred in astrocytes (20.9 particles/micron2) and neuronal perikarya (18.7 particles/micron2). The localization of taurine to presumptive inhibitory axon terminals provides anatomical support for the hypothesis that taurine may serve an inhibitory neurotransmitter role in the superficial dorsal horn of the spinal cord. On the other hand, its localization to astrocytes and endothelial cells within both the dorsal ventral horns implies that it serves other nonneuronal functions as well.  相似文献   
105.
人抗HBsAg噬菌体抗体Fab段基因的序列分析及表达   总被引:3,自引:0,他引:3  
对已建的噬菌体抗体库分离出来的人抗-HBs克隆进行了序列分析和表达研究,发现4个克隆中3个克隆的重链和轻链完全相同,DNA序列分析表明VH分别属于VH1亚群和Ⅱ亚群,其轻链VL分别属于VλⅡ亚群和VλⅠ亚群。构建了可溶性Fab段表达载体,显示出在细菌中表达的Fab段抗体与HBsAg特异性结合,这说明所筛选出来的噬菌体抗体具有HBdisplay status  相似文献   
106.
检测198例各型乙肝患者血小板功能的五个项目:血小板总数、粘附试验、聚集试验、血块退缩、血小板第3因子有效性,发现各期乙肝患者血小板功能的异常有显著性差异(P<0.01).并提示乙肝患者除有血小板数量的改变外,还有质量的改变,因此,全面的血小板功能检测可作为估计乙肝患者肝损害程度的辅助指标.  相似文献   
107.
以正常人外周血淋巴细胞的SCE率作为细胞遗传学指标,研究了Na_2SeO_3与AFB_1相互作用对细胞遗传物质的影响。结果表明,一定浓度的Na_2SeO_3(10 ̄(-5)mol)对AFB_1所诱发的SCE有明显的抑制作用,但当浓度达到10 ̄(-2)mol时,细胞增殖受到抑制,到10 ̄(-1)mol时细胞出现毒性现象。提示Na_2SeO_3具有抑变和细胞毒性双相作用。所以在Na_2SeO_3与AFB_1相互作用的SCE实验中应避免Na_2SeO_3的浓度过高而损伤培养的细胞。  相似文献   
108.
The immunoreactivity of apolipoprotein B (apo B) in plasma obtained from 238 unrelated black African male subjects from the People's Republic of Congo was analysed by non-competitive Enzyme Linked-Immunosorbent Assay (ELISA) with monoclonal BIP 45 anti-LDL antibody. The polymorphism detected by BIP 45 monoclonal antibody is identical to the Ag(c,g) polymorphism. Antibody BIP 45 distinguishes three apo B allotypes (immunophenotypes) encoded by the two allelic genes apo B Ag(c) and apo B Ag(g). Because of co-dominant transmission, genotypes may be inferred from allotypes, and it has been shown that BIP 45 binds strongly to the Ag(c) factor and only weakly to the allelic Ag(g) factor. Analysis of the Congolese plasma samples indicated that 67.65% of them bound BIP 45 with low affinity (Ag(c-,g+) genotype), 28.15% with intermediate affinity (Ag(c+,g+) genotype) and 4.20% with high affinity (Ag(c+,g-) genotype). According to the Hardy-Weinberg equilibrium, this corresponds to gene frequencies of 0.817 and 0.183 for the type Ag(g)/Ag(c) alleles, respectively. After adjustment for age and body-mass index, it was found that the Ag(c) allele decreases the apo B level by 9.62 mg/dl and that the Ag(g) allele increases apo B by 0.43 mg/dl. Therefore, as much as 4.30% of the genetic variance for apo B level could be accounted for by the Ag(c,g) gene locus.  相似文献   
109.
Abstract The major reason for late graft losses is chronic rejection. Recently, a large number of studies have indicated that proteolytic enzymes play an important role as mediators of glomerular injury. The cysteine proteinases cathepsins B and L degrade structural matrix proteins such as type I collagen and laminin. We investigated intraglomerular protease activities in 12 patients after kidney graftectomy because of end-tage renal disease following chronic rejection. A group of 12 patients undergoing nephrectomy because of cancer served as controls using only non-involved parts of the kidney. The activities of cathepsins B and L in homogenates of isolated glomeruli were measured fluorometrically methylcoumarylamidc substrates and related to DNA content. In rejected kidney allografts we observed significantly enhanced intraglomerular cathepsin B activity and cathepsin B + L activity.  相似文献   
110.
The paraneoplastic autoantibody, collapsin response-mediator protein (CRMP)-5 immunoglobulin G (IgG), is specific for neuronal cytoplasmic CRMP-5, and is usually associated with small-cell lung carcinoma or thymoma. We report on details of a movement disorder that followed anti-B-cell therapy in a patient with lymphoma, and was accompanied by CRMP-5 IgG.  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