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   26488篇
  免费   2669篇
  国内免费   1344篇
耳鼻咽喉   267篇
儿科学   302篇
妇产科学   455篇
基础医学   5613篇
口腔科学   508篇
临床医学   1376篇
内科学   3059篇
皮肤病学   556篇
神经病学   1266篇
特种医学   408篇
外国民族医学   13篇
外科学   1683篇
综合类   3975篇
现状与发展   6篇
预防医学   691篇
眼科学   235篇
药学   2677篇
  2篇
中国医学   617篇
肿瘤学   6792篇
  2024年   58篇
  2023年   385篇
  2022年   725篇
  2021年   1051篇
  2020年   847篇
  2019年   646篇
  2018年   601篇
  2017年   679篇
  2016年   702篇
  2015年   975篇
  2014年   1332篇
  2013年   1381篇
  2012年   1266篇
  2011年   1584篇
  2010年   1382篇
  2009年   1455篇
  2008年   1493篇
  2007年   1532篇
  2006年   1376篇
  2005年   1356篇
  2004年   1306篇
  2003年   1259篇
  2002年   1092篇
  2001年   1020篇
  2000年   915篇
  1999年   725篇
  1998年   637篇
  1997年   547篇
  1996年   450篇
  1995年   369篇
  1994年   231篇
  1993年   176篇
  1992年   110篇
  1991年   91篇
  1990年   52篇
  1989年   56篇
  1988年   66篇
  1987年   43篇
  1986年   47篇
  1985年   60篇
  1984年   62篇
  1983年   29篇
  1982年   49篇
  1981年   41篇
  1980年   42篇
  1979年   31篇
  1978年   32篇
  1977年   32篇
  1976年   22篇
  1973年   17篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
本文采用中和试验、沉降反应和解离试验对135例已知血型人精液中ABH血型物质的分泌强度进行了检验,并将其分为强、中、弱三型。这对区别个人血型物质含量及性犯罪的法医学鉴定均有重要意义。并证明了AB型人精液中A、B血型物质含量不均等现象,并且绝大多数人B型物质高于A型物质。  相似文献   
102.
《Movement disorders》2003,18(11):1240-1249
The identification of disease genes using family‐based approaches has provided important insights into the pathogenesis of Parkinson's disease (PD) demonstrating the importance of genetic studies on monogenic forms of the disease. We studied a large Cuban family with typical, late‐onset PD and probable autosomal dominant inheritance. Mean age at onset was 61.2 years (±12.53, 45–76). Other phenotypes such as essential tremor and atypical parkinsonism were observed in this family. We carried out a genome‐wide scan and linkage analyses. The genetic data were analyzed using a conservative model in which only patients with clinically definite or likely PD were considered affected, other phenotypes were regarded as “unknown.” Multipoint analyses yielded a maximum LOD of 2.26 between markers D19S221 and D19S840. Haplotype analysis showed a region on chromosome 19 shared by six of seven PD patients. The essential tremor phenotype and the atypical parkinsonism do not segregate with this haplotype, suggesting a different etiology. Our findings suggest the presence of a novel locus for PD on chromosome 19p13.3–q12. We propose that an oligogenic model with moderate contribution of two or three genes rather than a “pure” monogenic model might explain better the wide range in age at onset, the reduced penetrance and the phenotypical variability observed in PD families. © 2003 Movement Disorder Society  相似文献   
103.
48例非霍奇金淋巴瘤中的p53基因突变   总被引:1,自引:0,他引:1  
采用ABC和PCR-SSCP法在48例NHL中研究p53基因外显子5~8中发生突变的类型、频率与突变型p53蛋白的表达以及它们与病理分型、恶性程度的相关性。结果:突变型p53蛋白在NHL中的阳性率为41.7%,其中在弥漫型大细胞性淋巴瘤(DLCL)为75%,在非DLCL为35%,两者差异显著(P<0.05);在p53蛋白表达阳性的NHL中PCRSSCP阳性主要见于DLCL,检出率为15%,在非DLCL中PCR-SSCP均为阴性(P<0.05)。表明国人NHL,尤其在恶性程度很高的DLCL中存在p53基因突变,各型NHL都有不同程度的突变型p53蛋白表达  相似文献   
104.
Objective To test the hypothesis that p53 gene therapy combined with endostatin can enhance tumor response to radiation therapy of RM-1 mouse xenograft prostate cancer and to investigate its mechanism. Methods A mouse prostate cancer model was established. Then mice with xenograft tumor were randomly divided into group A (control), B (radiation), C (radiation and rAdp53), D (radiation and rh-endostatin) and E (radiation and rAdp53 and rh-endostatin). On day 1, rAdp53 was injected intra-tumorously with 1 × 1010 vp per animal to group C and E. From day 1 to 14, rh-endostatin was given 15 mg/kg intraperitoneally daily to group D and E. On day 4 single fraction of 15 Gy was given to tumors in groups B, C, D and E. Normal saline was injected intra-tumorously or intraperitoneaUy accordingly as control. No treatment was done to group A. Tumor volume was measured daily. Samples were collected on Days 5, 10 and 15. Ki67, CD31, p53 and VEGF were detected by means of immunohistochemistry. Results (1) Radiation alone, radiation combined with intra-tumorous injection of Adp53 and/or intraperitoneal injection of rh-endostatin resulted in tumor growth arrest of RM-1 cells in vivo (P = 0.000). Radiation combined with both rAdp53 and rh-endostatin was the most effective treatment (P < 0.05). (2) All the four treatment groups had a decreased expression of mutant type P53 (P = 0.000). The expression of Ki67 in groups B and C were equal (P 0.05) and increasing (P = 0.000), respectively. Group D had a up-down-up curve (P < 0.05), but group E had a up-down one. On day 5 the expresion of VEGF in group E was the lowest (P < 0.05). An increased expression of MVD compared with the control was shown, and MVD in groups C, D and E were always higher than that in the control (P < 0.05). Conclusions The limitation of radiotherapy could be overcome by combination with beth p53 gene therapy and endostatin on the growth of mouse prostate cancer cell. Radiation, rAdp53 and endostatin have their own role but they can be interacted with each other.  相似文献   
105.
癌基因c-fos、c-jun蛋白在鳞状细胞癌皮损中的表达及意义   总被引:3,自引:0,他引:3  
目的 探讨癌基因c fos、c jun的表达与皮肤鳞癌发生和发展的关系。 方法 采用免疫组化法对 6 0例皮肤鳞癌的c fos、c jun的表达情况进行检测 ,并与正常皮肤组织进行对照。 结果 c fos、c jun在正常皮肤组织不表达 ,在皮肤鳞癌中的表达阳性率分别为 6 1.7%和 4 8.3% ,其表达水平与癌组织的分化程度有关 (P <0 .0 5 ) ,肿瘤的分化程度越高其表达水平越高。 结论 c fos、c jun的表达水平可作为判定皮肤鳞癌分化的指标。  相似文献   
106.
Polymorphism p53 codon-72 and invasive cervical cancer: a meta-analysis.   总被引:4,自引:0,他引:4  
OBJECTIVES: Although some studies have reported that the arginine isoform on codon 72 of p53 increases the susceptibility to invasive cervical cancer, such data remain controversial. The objective of this study was to quantitatively summarize the evidence for such a relationship. METHODS: Our data sources consisted of a MEDLINE search of the literature published before December 2002, bibliography review, and expert consultation. Thirty-seven studies met the inclusion criteria. Information on sample size, study design, Hardy-Weinberg equilibrium, and method of genotype determination was abstracted by two reviewers using a standardized protocol. The overall odds ratio (OR) of the p53 gene on invasive cervical cancer was estimated using the Mantel-Haenzel method. RESULTS: The overall OR (95% confidence interval) for cervical cancer among those with the homozygous mutant (Arg/Arg) was 1.2 (1.1-1.3, P=0.001) compared with those with the heterozygous mutant (Arg/Pro). By a cellular type of cervical cancer, the overall OR among those with Arg/Arg was statistically significant in adenocarcinomas (1.7, 1.1-2.6, P=0.024), but not in squamous cell carcinomas (1.1, 0.9-1.2, P=0.960), compared with Pro/Pro. Compared with Arg/Pro, the OR among those with Arg/Arg was statistically significant in HPV types 16 (1,5, 1.2-2.0, P=0.002). CONCLUSIONS: Overall, the p53 gene was associated with increased risk for invasive cervical cancer. However, the risk varied by country, cellular, and HPV type.  相似文献   
107.
检测25例脑肿瘤中抑制癌基因P53突变情况。突用复合PCR,聚合酶链反应-=单链构象多态性分析法,统计学处理采用X^2检验。结果:P53基因总的突变率为44.0%,其中第5外显子突变率为28.0%,第6外显子突变率12.0%,第7外显子突变率为12.0%,第8外显子突变率16.0%;病理分级Ⅱ级及其以上突变为72.7%,  相似文献   
108.
石棉相关肿瘤p53基因突变的免疫组化及PCR—SSCP研究   总被引:3,自引:0,他引:3  
为了分析石棉相关肿瘤p53基因的突变特点,对石蜡包埋的石棉相关肿瘤p53基因突变体蛋白的表达进行了免疫组化观察,提取染色体DNA,对p53基因的第5、7、8外显子进行PCR-SSCP及测序分析。免疫组化观察发现:在分析的10例病例中有5例阳性。PCR-SSCP分析发现7例(8处)发生突变,其中4处集中在第8外显子上。5例腺癌中有4例发生p53基因突变。测序发现热点区突变。提示:石棉相关肿瘤p53基因突变率高。  相似文献   
109.
BACKGROUND: We have previously demonstrated that the proteolytic activity of Der p 1 selectively cleaves human CD25, the 55 kDa alpha subunit of the IL-2 receptor. As a result of cleavage of surface CD25, peripheral blood T cells produce less IFN-gamma and more IL-4, thereby leading to progressive polarization of the T cells towards a Th2 cytokine profile. Therefore, these observations underline the potential role of the proteolytic activity of Der p 1 in creating a microenvironment conducive for IgE synthesis. OBJECTIVE: To study the effect of T cells that have been conditioned by the proteolytic activity of Der p 1 on IgE synthesis by B cells. METHODS: We have examined this concept in experiments whereby T cells that have been exposed to either proteolytically active or inactive Der p 1 were cocultured with autologous B cells and IgE antibody synthesis was monitored. RESULTS: Here we demonstrate for the first time that coculturing T cells that have been in contact with proteolytically active Der p 1 with autologous B cells leads to augmentation of IgE antibody responses. CONCLUSIONS: The proteolytic activity of Der p 1 conditions human T cells, which then become empowered to trigger enhanced IgE synthesis by B cells.  相似文献   
110.
应用免疫且化的方法对59例肝细胞癌p21蛋白及增殖细胞核抗原的表达进行研究,并对两者在肝细胞癌中的表达关系进行比较。结果显示:p21在癌周肝组织的表达水平高于癌组织,在癌组织中的表达与肝细胞癌的分化程度有关,癌组织的分化降低,p21表达水平也随之降低p21的表达与PCNA的表达呈负相关关系(r=-0.327,P<0.01)。提示:p21的缺失表达可能促进PCNA合成的增加,对肝癌的发生发展起重要作用。  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