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   53155篇
  免费   4831篇
  国内免费   2306篇
耳鼻咽喉   386篇
儿科学   805篇
妇产科学   725篇
基础医学   14034篇
口腔科学   918篇
临床医学   3650篇
内科学   7706篇
皮肤病学   1419篇
神经病学   2048篇
特种医学   670篇
外国民族医学   25篇
外科学   3335篇
综合类   7614篇
现状与发展   11篇
预防医学   1550篇
眼科学   436篇
药学   4121篇
  3篇
中国医学   1060篇
肿瘤学   9776篇
  2024年   116篇
  2023年   658篇
  2022年   1278篇
  2021年   1699篇
  2020年   1443篇
  2019年   1306篇
  2018年   1270篇
  2017年   1362篇
  2016年   1443篇
  2015年   1957篇
  2014年   2664篇
  2013年   3021篇
  2012年   2646篇
  2011年   3524篇
  2010年   3041篇
  2009年   3288篇
  2008年   3114篇
  2007年   3141篇
  2006年   2908篇
  2005年   2720篇
  2004年   2518篇
  2003年   2358篇
  2002年   2014篇
  2001年   1767篇
  2000年   1557篇
  1999年   1294篇
  1998年   1181篇
  1997年   962篇
  1996年   868篇
  1995年   783篇
  1994年   561篇
  1993年   425篇
  1992年   246篇
  1991年   218篇
  1990年   115篇
  1989年   94篇
  1988年   84篇
  1987年   51篇
  1986年   55篇
  1985年   68篇
  1984年   77篇
  1983年   37篇
  1982年   55篇
  1981年   50篇
  1980年   50篇
  1979年   35篇
  1978年   35篇
  1977年   34篇
  1976年   20篇
  1973年   17篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
VEGF和p53在胰腺癌中的表达及意义   总被引:1,自引:0,他引:1  
目的 探讨胰腺癌组织中血管内皮生长因子 (VEGF)及p5 3蛋白的表达及其临床病理意义。方法 采用SP免疫组织化学方法 ,对 46例胰腺癌组织中VEGF及 p5 3蛋白的表达进行检测。结果 VEGF与 p5 3表达率分别为 65 .2 %和 5 8.7%。p5 3表达与VEGF表达呈明显正相关(P <0 .0 5 )。VEGF表达与胰腺癌淋巴结转移 (P <0 .0 5 )和远处转移 (P <0 .0 1)显著相关 ,而与肿瘤大小 ,病理学分级无关 ,p5 3表达与胰腺癌远处转移 (P <0 .0 5 )显著相关 ,而与肿瘤大小 ,病理学分级及淋巴结转移无关。结论 在胰腺癌中 ,VEGF表达与 p5 3蛋白的表达呈正相关 ,在胰腺癌的转移中起重要作用  相似文献   
52.
老年2型糖尿病患者胰岛素抵抗相关指标的检测和意义   总被引:1,自引:1,他引:0  
目的:探讨老年2型糖尿病胰岛素抵抗(IR)及其相关性,为老年2型糖尿病的合理防治提供临床依据。方法:选择120例老年2型糖尿病患者,按胰岛素敏感指数(HOMA)胰岛素抵抗(HOMA-IR)50百分位点将患者分为两组:胰岛素相对敏感组(HOMA-IR<3.56)和胰岛素相对抵抗组(HOMA-IR≥3.56),比较体重指数(BMI)、腰/臀比(WHR)、血压、血生化学检查等指标。用年龄>40岁,<60岁的2型糖尿病患者做对照组。结果:两组老年患者在年龄、性别、舒张压、空腹血糖、胆固醇、高密度脂蛋白、糖化血红蛋白、HOMA胰岛β细胞功能方面无差异;但BMI、WHR、收缩压、甘油三脂、空腹胰岛素、HOMA-IR差异具有显著性。多线性回归分析后,只有腰/臀比、收缩压、甘油三脂、HOMA-IR存在统计学差异。老年患者与对照组相比,IR发生率明显增加,且两者腰/臀比、收缩压、甘油三脂方面也差异显著。结论:IR与老年2型糖尿病密切相关,是临床防治糖尿病的重要靶点。  相似文献   
53.
Polysaccharidenucleicacidfractionofbacilluscalmetteguerin (BCG PSN ,SiqikangInjection)andthymopeptidesarenowtwowidelyusedimmunomod ulatorsinclinicalpractice .Theyareusuallyusedasanadjuvanttherapyforvirusinfection ,autoimmunediseasesandneoplasms ,whichhavebeenclinicallyprovedtobeeffective .Somereportsdemonstratedthattheybothcanstimulatetheproliferationanddif ferentiationofT lymphocytes.However ,theexactmechanismshavenotbeenelucidatedyet .InordertocomparetheirmodulatingmechanismsonT lympho c…  相似文献   
54.
火箭推进剂呼吸防护装备研究现状及发展趋势   总被引:4,自引:2,他引:2  
本文对呼吸防护装备的应用、发展进行了综述,分析了火箭推进剂毒性对呼吸防护的要求和国内推进剂呼吸防护研究现状,对推进剂专用呼吸防护装备的发展趋势进行了探讨。  相似文献   
55.
Polycyclic aromatic hydrocarbons (PAHs), such as benzo[a]pyrene (BaP), are carcinogens suggested to be involved in development of human cancer. Several recent studies have reported that PAHs can activate estrogen receptors (ER), either directly or indirectly by producing estrogenic metabolites. We hypothesized that the activation of ER by PAHs or their metabolites could induce cell proliferation in estrogen-sensitive cells. In the present study, we found that two PAHs, benz[a]anthracene (BaA) and BaP, can stimulate proliferation of human breast carcinoma MCF-7 cells at concentrations 100 nM and higher. This effect was ER-dependent, because it was blocked by the pure antiestrogen ICI 182,780. Although both PAHs partially inhibited S-phase entry and DNA synthesis induced by 17beta-estradiol, they stimulated S-phase entry when applied to MCF-7 cells synchronized by serum deprivation. This was in contrast with model antiestrogenic aryl hydrocarbon receptor ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin, which fully suppressed S-phase entry. BaP, which is a strong mutagen, was found to induce p53 tumor suppressor expression, a partial S-phase arrest and at higher concentrations also cell death. Pifithrin-alpha, a synthetic inhibitor of p53 activity, abolished both S-phase arrest and apoptosis induced by genotoxic PAHs, and it potentiated the proliferative effect of BaP. Thus, both genotoxic and nongenotoxic events seem to interact in the effects of BaP on cell proliferation. Taken together, our data indicate that both BaA and BaP can stimulate cell proliferation through activation of ER. The proliferative effects of these carcinogenic compounds might contribute to tumor promotion in estrogen-sensitive tissues.  相似文献   
56.
57.
A 15-year-old boy with a terminal deletion of the short arm of chromosome 4 is described. The patient has a mild clinical phenotype that is incompatible with Wolf-Hirschhorn syndrome. Careful neurological examination including CT scan did not show any signs of Huntington disease. The chromosomal breakpoint was analyzed by means of polymorphic DNA probes localized close to the tentative Huntington (HD) locus. The breakage has occurred between D4S43 and D4S90 loci and thus deletes part of the chromosomal candidate regions for the HD locus. © 1992 Wiley-Liss, Inc.  相似文献   
58.
Background :
The aim of this study was to examine nuclear p53 overexpression in transitional cell carcinoma of the bladder, adenocarcinoma of the prostate, and renal cell carcinoma.
Methods :
Forty-four pathologic specimens from 39 bladder cancer patients, 41 prostatic adenocarcinoma, and 39 renal cell carcinoma specimens were analyzed immunohistochemically with D07 monoclonal antibody to detect the expression of the mutant p53 gene. Overexpression was said to occur when the number of positively-stained tumor nuclei were≥ 10% in each specimen. p53 overexpression was correlated with the clinical and histopathological features of these cancers.
Results :
Nuclear p53 overexpression occurred in 18.2% of transitional cell bladder cancer specimens, 12.2% of prostate cancer specimens, and 17.9% of renal cell cancer specimens. Statistical analyses showed that grade, vascular invasion, and necrosis in bladder cancer, a high Gleason score in prostate cancer, and the 1-year mortality rate in renal cancer were significantly related with p53 nuclear overexpression (P<0.05).
Conclusion :
Using the D07 monoclonal antibody, nuclear p53 overexpression is relatively uncommon in urologic malignancies, and moderately correlates with several histopathological and clinical features of urologic malignancies.  相似文献   
59.
CD44 is the principal cell surface receptor for hyaluronate. Variant forms of the receptor, produced by alternative splicing, have been found to be associated with tumor progression in a variety of cancers. Based on investigations at the RNA level, it has recently been proposed that expression of CD44 variant V2 was present in urothelial cancer but not in normal urothelium. Since a distinctive marker for urothelial cancer would be extremely useful, frozen sections of normal urothelium and urothelial cancer were examined for expression of standard CD44 and CD44V2. Frozen sections of specimens of 35 patients with transitional cell carcinoma of the bladder, 16 specimens of normal bladder and 5 ureters were examined. Immunohistochemical staining was performed using a polyclonal antibody to CD44V2 (PAB CD44V2), a monoclonal antibody to CD44V2 (MAB CD44V2) and a monoclonal antibody to CD44S (MAB CD44S). CD44V2 and CD44S were also measured in lysates of urine sediments from 21 patients by enzyme-linked immunoabsorbent assay (ELISA). All investigated transitional cell carcinomas expressed CD44V2. There was no differentiation between invasive and noninvasive carcinoma. CD44V2 was also expressed in normal urothelium. Standard CD44 was expressed by the transitional cell carcinoma, normal urothelium, musculature and interstitial tissue. The amount of CD44V2 and CD44S in lysates of urine sediments is not correlated to diagnosis. In contrast to investigations at the RNA level, CD44V2 on the protein level seems not to be a distinctive marker for urothelial cancer. Therefore, CD44V2 will not be a useful diagnostic marker for detection of transitional cell carcinoma.  相似文献   
60.
Background: The overexpression of p53 has been found to be correlated with prognosis of some carcinomas, including gastric cancer, but no studies have reported on its relationship to the location of gastric cancer. In the present study, we compared the p53 expression of proximal and distal gastric cancer concerning histopathology and prognosis. Methods: A total of 170 tumors in the patients with proximal (80 cases) and distal (90 cases) gastric cancer were studied by immunohistochemical methods. Results: p53 immunopositivity was detected in 28.8% of all tumors. The p53-positive expression in proximal gastric cancer was higher than in distal gastric cancer (38.8% vs. 20.0%, p<0.05). A 5-year survival analysis showed that there is no significant difference between tumors that are p53 positive and p53 negative. No correlation was found between p53 expression and histopathology of gastric cancer. Conclusion: p53 nuclear staining is not useful as a prognostic indicator or as a parameter in gastric cancer.  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