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   29595篇
  免费   2862篇
  国内免费   1457篇
耳鼻咽喉   273篇
儿科学   305篇
妇产科学   488篇
基础医学   6253篇
口腔科学   537篇
临床医学   1487篇
内科学   3471篇
皮肤病学   654篇
神经病学   1517篇
特种医学   418篇
外国民族医学   14篇
外科学   1823篇
综合类   4188篇
现状与发展   6篇
预防医学   764篇
眼科学   269篇
药学   3462篇
  2篇
中国医学   838篇
肿瘤学   7145篇
  2024年   60篇
  2023年   432篇
  2022年   680篇
  2021年   1163篇
  2020年   949篇
  2019年   753篇
  2018年   682篇
  2017年   781篇
  2016年   802篇
  2015年   1094篇
  2014年   1553篇
  2013年   1593篇
  2012年   1451篇
  2011年   1866篇
  2010年   1631篇
  2009年   1710篇
  2008年   1704篇
  2007年   1732篇
  2006年   1569篇
  2005年   1519篇
  2004年   1432篇
  2003年   1362篇
  2002年   1158篇
  2001年   1055篇
  2000年   951篇
  1999年   744篇
  1998年   653篇
  1997年   563篇
  1996年   459篇
  1995年   385篇
  1994年   241篇
  1993年   185篇
  1992年   114篇
  1991年   97篇
  1990年   57篇
  1989年   59篇
  1988年   65篇
  1987年   42篇
  1986年   47篇
  1985年   61篇
  1984年   70篇
  1983年   34篇
  1982年   57篇
  1981年   44篇
  1980年   50篇
  1979年   33篇
  1978年   32篇
  1977年   34篇
  1976年   24篇
  1975年   18篇
排序方式: 共有10000条查询结果,搜索用时 24 毫秒
21.
胃癌组织p16基因蛋白表达的意义   总被引:9,自引:4,他引:5  
目的 检测 p1 6基因蛋白在胃癌组织、癌旁组织中的表达及其分布特点 ,分析其与胃癌临床病理学特征及预后的关系 .方法 采用 S- P免疫组织化学法对 53例胃癌组织及 35例癌旁组织进行 p1 6蛋白的定位观察 .结果 各病理类型胃癌组织、癌旁组织均有 p1 6基因蛋白表达 .阳性率分别为 62 .3% (33/53)和 88.6% (31 /35) ,阳性细胞的棕黄色颗粒主要位于细胞核 .胃癌 p1 6基因蛋白表达与性别、年龄、肿瘤部位在统计学上无差异 (P>0 .0 5) ;而与组织学类型、病理分级、淋巴结转移、临床病理分期在统计学上有差异 (P<0 .0 5) .p1 6蛋白阳性者 5年生存率 51 .0 %高于 p1 6蛋白阴性者 2 0 .0 % (P<0 .0 5) .结论  p1 6基因缺失和表达水平的改变与胃癌发生、发展密切相关 ,检测 p1 6基因蛋白表达可作为辅助临床判断胃癌的生物学行为及推测预后的指标  相似文献   
22.
人原发性肝癌中p16基因表达及CpG岛甲基化状态的研究   总被引:1,自引:0,他引:1  
目的 进一步探讨人原发性肝癌中 p16基因 m RNA转录水平变化与其基因启动子区 Cp G岛甲基化的关系 ,及其在肝癌发生中的意义。方法 采用狭缝印迹杂交检测 2 0例人原发性肝癌及相应的癌旁、远癌组织及 2例正常人肝组织中 p16基因 m RNA表达水平 ,以甲基化特异性 PCR分析各组织中 p16基因启动子区 Cp G岛的甲基化状况 ,并进行统计分析。结果  2 0例人原发性肝癌中 14例 (70 % ) p16 m RNA水平比远癌组织显著降低 ;13例 (6 5 % )显示 p16基因启动子区 Cp G岛甲基化 ,其中 84 .6 % (11例 )伴 p16 m RNA转录水平降低。结论 人原发性肝癌中存在高频率的 p16基因表达失活 ,其主要机制可能是启动子区 Cp G岛甲基化抑制了基因的转录 ,在人原发性肝癌的发生发展中有重要作用。其临床诊断和治疗意义有待进一步深入研究。  相似文献   
23.
p14ARF基因和核转录因子E2F-1在细胞周期调控,细胞凋亡和肿瘤发生中具有重要作用。近年来,有研究表明p14ARF在肺癌中的表达率低于正常组织,E2F-1的表达率高于正常组织。本文将就p14ARF、E2F-1与肺癌的关系进行综述。  相似文献   
24.
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   
25.
26.
Open, Double-Blind and Long-Term Study of Vigabatrin in Chronic Epilepsy   总被引:5,自引:4,他引:1  
We performed an open, double-blind, and long-term study of vigabatrin (gamma-vinyl-GABA, GVG) in patients with treatment-resistant epilepsy who were receiving only one or at most two standard antiepileptic drugs (AEDs). The novel design included a parallel, double-blind, placebo-controlled phase that minimized the number of patients receiving placebo and allowed determination of the optimum dose of GVG for each patient before initiation of the double-blind phase. The study was divided into four phases. The first phase was a 6-week period of baseline observation. In the second phase, GVG was added openly to previous AEDs for 8 weeks. During the first 2 weeks of this phase, the dose of GVG was increased weekly and then, in the absence of adverse effects, was held constant for the next 6 weeks. At the end of this open phase, seizure frequency during the 6 weeks of constant treatment was compared with the baseline seizure frequency for each patient. Patients who experienced reduction greater than 50% in the frequency of any seizure type during the open phase were defined as responders. These responders were then entered into the third and double-blind phase, in which they were randomly allocated wither to continue active GVG treatment or placebo for 8 weeks. Thirty-three patients entered the study; 31 of 33 patients completed the initial open phase. Twenty patients achieved a reduction greater than or equal to 50% in the frequency of one or more seizure types and were eligible for the double-blind phase; 10 were randomized to continue GVG and 10 were randomized to placebo.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
27.
BACKGROUND: Exposure to a high level of house dust mite allergens (HDMAs) is considered as a risk factor for HDM sensitization and development of asthma in genetically disposed people. Mattresses are one of the most important sources of HDMA in people's living environment. OBJECTIVE: The aim of this study was to evaluate the association between mattress characteristics and HDMA concentrations on mattresses. METHODS: Dust samples of mattress surfaces were taken to evaluate the level of Der p 1 allergen. All participants filled in a questionnaire about the type of mattress, the type of covering (upper layer) of the mattress, dwelling characteristics and cleaning habits. Humidity and temperature of the bedroom were measured at the time of dust sampling. RESULTS: One hundred and sixty-eight questionnaires were filled in. Synthetic upper layer of the mattress was associated with a higher level of Der p 1 compared with cotton upper layer (2.6 vs. 0.8 microg/g Der p 1). Moreover, higher relative humidity (RH) was associated with significant higher concentrations and density of Der p 1. CONCLUSIONS: Two factors were associated with lower levels of Der p 1 found on mattresses, namely: a cotton upper layer of the mattress compared with a layer of synthetic material and lower RH at the time of sampling. As far as we know, the association between type of upper layer and concentration of Der p 1 has not been described before and could lead to the formulation of practical advices in order to reduce HDMA concentrations on mattresses.  相似文献   
28.
p16INK4A (p16) binds to cyclin-dependent kinase 4/6 and negatively regulates cell growth. Recent studies have led to an understanding of additional biologic functions for p16; however, the detailed mechanisms involved are still elusive. In this article, we show an unexpected expression of anion exchanger 1 (AE1) in the cytoplasm in poorly and moderately differentiated gastric and colonic adenocarcinoma cells and in its interaction with p16, thereby sequestrating the protein in the cytoplasm. Genetic alterations of p16 and AE1 were not detectable. Forced expression of AE1 in these cells sequestrated more p16 in the cytoplasm, whereas small interfering RNA-mediated silencing of AE1 in the cells induced the release of p16 from the cytoplasm to the nucleus, leading to cell death and growth inhibition of tumor cells. By analyzing tissue samples obtained from patients with gastric and colonic cancers, we found that 83.33% of gastric cancers and 56.52% of colonic cancers coexpressed AE1 and p16 in the cytoplasm. We conclude that AE1 plays a crucial role in the pathogenesis of gastric and colonic adenocarcinoma and that p16 dysfunction is a novel pathway of carcinogenesis.  相似文献   
29.
p53,p16,PCNA蛋白在食管癌中的表达及其临床意义   总被引:3,自引:0,他引:3  
目的探讨p53,p16,PCNA蛋白在食管癌中的表达及临床意义。方法用免疫组织化学染色SP法对62例食管癌标本进行p53,p16,PCNA蛋白测定。结果62例食管癌中,p53,PCNA蛋白阳性表达均为71.0%(44/62),p16缺失率48.4%(30/62)。p16缺失与肿瘤浸润深度、淋巴结转移密切相关(P<0.05、P<0.01)。而p53,PCNA蛋白同时表达56.5%(35/62),亦与肿瘤浸润深度、淋巴结转移密切相关(P<0.05、P<0.01)。结论食管癌p53,PCNA蛋白同时表达及p16缺失可视为危险预后因素。  相似文献   
30.
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