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   10916篇
  免费   998篇
  国内免费   869篇
耳鼻咽喉   88篇
儿科学   146篇
妇产科学   142篇
基础医学   1308篇
口腔科学   127篇
临床医学   1435篇
内科学   1622篇
皮肤病学   129篇
神经病学   588篇
特种医学   503篇
外国民族医学   10篇
外科学   997篇
综合类   1736篇
现状与发展   4篇
一般理论   1篇
预防医学   762篇
眼科学   466篇
药学   1143篇
  8篇
中国医学   593篇
肿瘤学   975篇
  2024年   30篇
  2023年   152篇
  2022年   427篇
  2021年   544篇
  2020年   388篇
  2019年   364篇
  2018年   402篇
  2017年   335篇
  2016年   336篇
  2015年   479篇
  2014年   585篇
  2013年   527篇
  2012年   818篇
  2011年   924篇
  2010年   611篇
  2009年   437篇
  2008年   632篇
  2007年   538篇
  2006年   532篇
  2005年   555篇
  2004年   348篇
  2003年   305篇
  2002年   258篇
  2001年   224篇
  2000年   289篇
  1999年   277篇
  1998年   189篇
  1997年   154篇
  1996年   171篇
  1995年   122篇
  1994年   115篇
  1993年   71篇
  1992年   74篇
  1991年   70篇
  1990年   79篇
  1989年   59篇
  1988年   58篇
  1987年   57篇
  1986年   45篇
  1985年   36篇
  1984年   21篇
  1983年   21篇
  1982年   13篇
  1981年   15篇
  1980年   14篇
  1979年   10篇
  1977年   11篇
  1976年   14篇
  1974年   6篇
  1973年   9篇
排序方式: 共有10000条查询结果,搜索用时 20 毫秒
121.
成都地区汉族人群ACE基因多态性与血清ACE活性的相关性   总被引:6,自引:0,他引:6  
为调查中国汉族人群血管紧张素转换酶(ACE) 基因多态性分布及与血清ACE(SA CE)活性的相关性.采用比色法和PCR技术,对90例健康汉族人群进行SACE活性和ACE基因插入/缺失(I/D)多态性的检测.结果显示:中国汉族人群ACE基因DD型占18%,DI型占44%,II 型占38%, D和I等位基因频率分别为0.40和0.60.ACE基因多态性与SACE活性密切相关,提示不同种族间ACE基因分布存在着差异,中国汉族人群ACE基因多态性以II型和I等位基因占优势;SACE活性受ACE基因I/D多态性的影响.  相似文献   
122.
为了解2型糖尿病及其血管并发症患者血清ACE(SACE)活性的变化, 采用比色法对1 27例2型糖尿病患者和90例正常人进行SACE活性的检测。结果显示:糖尿病患者SACE活性(45 9. 51±175.85U)明显高于正常人(321.14±121.27U);糖尿病肾病组SACE活性(548.27±166.60 U)明显高于非肾病组(383.20±139-00U),但微量蛋白尿组(528.10±190.70U)与大量蛋白 尿 组(545.83±138.60U)SACE活性比较无统计学意义(P>005);糖尿病视网膜病变 组SACE活性(465.64±178.93 U)与无视网膜病变组(449.07±170.04U)比较也无统计学意义;糖尿病患者SACE活性与病程 、 血压、血脂和血糖无关。提示ACE可能仅参与了糖尿病和糖尿病肾病的发病,而与糖尿病肾 病进行性发展、糖尿病视网膜病变和高血压发病无关。  相似文献   
123.
京剧嗓音的声学分析及音域特征   总被引:3,自引:0,他引:3  
OBJECTIVE: To get the objective acoustic parameters of the voice of Beijing Opera actors and set a foundation for the training and protection of the special professional voice. METHODS: Seventy-three (age 16-57 years) professional actors and students were asked to produce sustained comfortable vowels /a/ and /i/, and to sing two pieces of songs which were in the category of Xipi and Erhuang respectively. Dr. Speech for windows version 3.0 was used to get the acoustic parameters of the vowels and the songs. RESULTS: F0 of the vowels /a/ and /i/ of different Hangdangs were Chou (272.6 +/- 42.0) Hz (mean +/- s), (304.2 +/- 22.1) Hz; Xiaosheng (499.3 +/- 34.0) Hz, (485.4 +/- 18.7) Hz; Laosheng (335.6 +/- 60.0) Hz, (317.9 +/- 45.1) Hz; Hualian (319.0 +/- 61.3) Hz, (340.1 +/- 68.8) Hz; Laodan (427.6 +/- 47.2) Hz, (437.7 +/- 45.8) Hz; Huadan (535.8 +/- 48.8) Hz, (561.6 +/- 29.2) Hz; Qingyi (548.0 +/- 69.5) Hz, (543.5 +/- 79.3) Hz; these and other acoustic parameters of vowels such as Jitter, Shimmer and NNE were all within the normal range given by the software. The vocal range of Beijing Opera actors was from 1.7 to 2.8 oct, and most of the highest and the lowest pitches were higher than that of tenor or soprano. CONCLUSIONS: These findings may help to provide insight regarding the acoustic characteristics of the voice of Beijing Opera actors.  相似文献   
124.
H Wu  S Qu  Q Huang  J Deng  Y Zhang  J Li 《华西医科大学学报》2000,31(2):169-70, 179
This study was aimed at the angiotensin converting enzyme (ACE) gene insertion/deletion(I/D) polymorphism distribution in Chinese and its relationship with serum ACE activity(SACE). SACE activity and ACE gene polymorphism in 90 healthy persons in Chengdu region were investigated using a spectrophotometric assay and the PCR technique, respectively. The results showed that, in the Hans, DD genotype of ACE gene was 18%, DI genotype 44%, and II genotype 38%. Allele frequencies were 0.40 for the D allele and 0.60 for the I allele. There were significant relationships between ACE I/D polymorphism and SACE activity. The results suggest that ACE genotype distribution be different between races, that II genotype and I allele be more frequent in Chinese, and that SACE activity be under the influence of a genetic polymorphism of ACE in Chinese.  相似文献   
125.
目的 通过使用不同成像序列及接收线圈,寻找最佳非增强门脉磁共振成像技术。方法 对20例上腹部受检者行门静脉成像。以轴位为定位像,行冠状位扫描。其中10例GRASS、GRASS+EATSAT、SPGR、SPGR+FATSAT4种序列扫描;10例以体线圈、GPF线圈及胸腰椎线圈和GRASS扫描。所得图像均进行MIP重建,并对MIP重建图像门静脉显示效果进行对比评价。结果 SPGR,GRASS信噪比、对  相似文献   
126.
H Wu  S Qu  Y Zhang  J Deng  J Li  J Zhou 《华西医科大学学报》2000,31(3):373-375
This investigation was made with reference to the changes of serum angiotensin converting enzyme (SACE) activity in type 2 diabetes and its vascular complications. SACE activity was studied in 127 type 2 diabetic patients and 90 healthy persons by using a spectrophotometric assay. The results showed SACE activity was obviously higher in diabetic patients (459.51 +/- 175.85 U) than in healthy persons (321.14 +/- 121.27 U); SACE activity was significantly higher in type 2 diabetic patients with diabetic nephropathy (548.27 +/- 166.60 U) than in patients without diabetic nephropathy (383.2 +/- 139.00 U), but there was no difference between patients with microalbuminuria and macroalbuminuria; no statistical difference was detected in SACE activity between diabetic patients with diabetic retinopathy (465.64 +/- 178.93 U) and without retinopathy (449.07 +/- 170.04 U); SACE activity was not associated with the course of diabetes, blood pressure, blood lipid and blood glucose. These data suggest that raised SACE activity might only play a role in the initiation of type 2 diabetes and diabetic nephropathy, but not relate to the progress of diabetic nephropathy, the onset of diabetic retinopathy and hypertension.  相似文献   
127.
为了解肝素对脂多糖诱导人肾小球系膜细胞增殖和细胞因子分泌的影响。作者采用四甲基偶氮唑蓝比色分析法及生物活性法,分别测定了人肾小球MC增殖和细胞因子的分泌情况。结果显示;在正常培养条件下,人肾上球MC分泌一定理的白细胞介素6(IL-60和肿瘤坏死因子α(TNF-α)。脂多糖诱导MC增殖及分泌IL-6,TNF-α。高浓度的肝素(500U/ml)促进MC增殖及分泌细胞因子,低浓度的肝素(5U/ml)抑制  相似文献   
128.
Urban-rural comparison of HBV and HCV infection prevalence in eastern China   总被引:6,自引:0,他引:6  
The present study was initiated to make and urban-rural comparison of the prevalence of cases positive to hepatitis B and C virus(HBV and HCV,respectively)infection markers in densely populated eastern half of China.For this purpose.10 survey sites were selected,i.e.,six sites in urban areas(the city group;Beijing,shangahi and four provincial capitals)and four sites in rural areas(the village group;one village each in Jilin and Shandong provinces,and two villages in Shaanxi Province),About 50 adult women per site volunteered to participate,from whom 494 valid bllod samples were collected.Positivities to HBsAg(HBsAg^ ),anti-HBs(anti-HBs^ )and antiHBc(anti-HBc^ )were examined by RIA methods.and that to anti-HCV(anti-HCV^ )by either EIA or RIA.Those positive to any one of the three HBV infection markers were taken as HBV infection-positive(HBV^ ).The prevalence of HBsAg^ ,HBV^ and anti-HBc^ was 8%,70%and 2.7% in the city group,and 8%,65% and 2.0%in the village group,and no significant difference was found between the two groups.The overall prevalence was 8% for HBsAg^ ,68% for HBV^ ,and 2.4% for anti-HVC^ ,The results were discussed in reference to some 20 papers each on HBV^ and anti-HCV^ prevalence in China published since(1991),The reviewing of these papers of anti-HCV was low(well below 5%),and that no substantial difference was found between the rural and urban populations.  相似文献   
129.
小学生学习困难综合干预前瞻性研究   总被引:6,自引:2,他引:4  
目的 验证综合干预治疗小学生学习困难(LD)的效果。方法 84例LD学生分成干预组(43例)和不干预组(41例)作对照,用教育、家庭、学校干预和心理治疗及药物治疗进行综合干预。结果 二年后,干预组有效率(76.74%)、学习成绩及智商明显高于不干预组,LD和行为问题发生率明显低于后者(P〈0.05~0.01)。结论 综合干预是通过增强学生学习自信心,减少或消除心理行为问题,提高智力水平等综合发挥效  相似文献   
130.
为探讨铁氰化钾〔potassiumferricyanideK3Fe(CN) 6〕对血管基膜的特殊染色作用 ,以铁氰化钾作为染色剂对生物样本进行处理 ,并在透射电镜下观察血管基膜对该物质的反应。结果显示 ,用铁氰化钾浸染后的病理标本 ,血管基膜部位染色明显加深 ,电子密度增高。提示 :铁氰化钾可以与血管基膜结合 ,从而为研究血管基膜的超微病理变化提供了 1种新的电子染色技术  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