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   147988篇
  免费   14710篇
  国内免费   9697篇
耳鼻咽喉   1137篇
儿科学   2225篇
妇产科学   1889篇
基础医学   15465篇
口腔科学   3022篇
临床医学   19159篇
内科学   20100篇
皮肤病学   1601篇
神经病学   6622篇
特种医学   5288篇
外国民族医学   46篇
外科学   13997篇
综合类   28327篇
现状与发展   36篇
一般理论   14篇
预防医学   11923篇
眼科学   3637篇
药学   16381篇
  162篇
中国医学   10219篇
肿瘤学   11145篇
  2024年   644篇
  2023年   2404篇
  2022年   6103篇
  2021年   7640篇
  2020年   6050篇
  2019年   4605篇
  2018年   4820篇
  2017年   4830篇
  2016年   4304篇
  2015年   6705篇
  2014年   8240篇
  2013年   8436篇
  2012年   12166篇
  2011年   13073篇
  2010年   9333篇
  2009年   7594篇
  2008年   9166篇
  2007年   8632篇
  2006年   7840篇
  2005年   7172篇
  2004年   5057篇
  2003年   4468篇
  2002年   3780篇
  2001年   2920篇
  2000年   2804篇
  1999年   2626篇
  1998年   1587篇
  1997年   1570篇
  1996年   1229篇
  1995年   1148篇
  1994年   961篇
  1993年   581篇
  1992年   649篇
  1991年   571篇
  1990年   504篇
  1989年   422篇
  1988年   339篇
  1987年   346篇
  1986年   244篇
  1985年   199篇
  1984年   128篇
  1983年   88篇
  1982年   63篇
  1981年   50篇
  1980年   36篇
  1979年   46篇
  1978年   18篇
  1974年   17篇
  1973年   17篇
  1966年   18篇
排序方式: 共有10000条查询结果,搜索用时 21 毫秒
991.
多囊卵巢综合征高雄激素血症患者瘦素水平的检测及评价   总被引:1,自引:0,他引:1  
目的探讨多囊卵巢综合征高雄激素血症进行患者瘦素(Leptin)水平及其与睾酮(T)、体重指数(BMI)的关系.方法采用放射免疫分析法(RIA)检测53例PCOS患者血清瘦素水平,其中非肥胖组PCOS患者36例,正常对照30例;肥胖组PCOS患者17例,正常对照20例.结果肥胖组及非肥胖组PCOS高雄激素血症患者血清瘦素水平均明显高于相当体重指数的正常对照组,有显著差异(p均<0.01);两组瘦素水平分别与其睾酮水平进行相关性分析,均显著正相关(r=0.51,p<0.01和r=0.58,p<0.01);非肥胖组PCOS患者血清瘦素水平与其BMI相关分析显示,无相关性;肥胖组PCOS患者血清瘦素水平与其BMI进行相关分析,显著正相关(p=0.56,p<0.01).结论高瘦素血症是PCOS患者的内分泌特征之一,PCOS高雄激素血症的形成与高瘦素水平有关;超重或肥胖的PCOS高雄激素血症患者存在瘦素抵抗现象.  相似文献   
992.
认知疗法治疗强迫症的对照研究   总被引:2,自引:0,他引:2  
目的 探讨认知疗法治疗强迫症的疗效。方法 对 6 0例符合 CCMD-2 -R诊断标准 ,且 Y-BOCS量表评分≥ 1 6分的强迫症病人 ,随机分到认知治疗组 ( 30例 )和氯丙咪嗪组 ( 30例 ) ,两组在氯丙咪嗪常规治疗的同时 ,其中一组加用认知治疗 ,共治疗 8周。在治疗前、后两组均进行临床疗效评估和 Y-BOCS量表评分。结果 认知治疗组痊愈 1 1例、显效 1 6例、有效 3例。氯丙咪嗪组痊愈 6例、显效 1 4例、有效 1 0例。两组痊愈和显效比较有显著差异 ( P<0 .0 5 )。 Y-BOCS量表减分率 :认知治疗组 5 4 .90 % ,氯丙咪嗪组 4 2 .33% ,两组比较有显著差异 ( P<0 .0 5 )。结论 认知疗法配合药物治疗强迫症比单用氯丙咪嗪治疗强迫症疗效更好  相似文献   
993.
Primary follicular large cell lymphoma of the testis in a child   总被引:3,自引:0,他引:3  
Primary follicular lymphoma of the testis in childhood is extremely rare. To our knowledge, only 5 cases have been reported to date. We report a case in a 6-year-old boy who presented with painless right scrotal enlargement. Right radical orchiectomy revealed a follicular large cell lymphoma with diffuse areas confined to the testis and epididymis, clinical stage IE. Immunohistochemical stains demonstrated that the neoplastic cells were of B-cell lineage, positive for CD10, CD20, CD79a, and BCL-6. Staining for CD21 accentuated networks of dendritic reticulum cells within the nodules. The cells were negative for BCL-2, p53, and T-cell antigens. There was no evidence of the t(14;18) detected by polymerase chain reaction. The data suggest that follicular lymphoma of the testis in children has a different pathogenesis than follicular lymphoma in adults.  相似文献   
994.
995.
原位PCR技术检测石蜡包埋脑组织中人巨细胞病毒DNA   总被引:6,自引:0,他引:6  
应用原位聚合酶链反应(ISPCR)技术检测了25例尸检畸形胎儿石蜡包埋脑组织中人巨细胞病毒(HCMV)DNA,并与普通PCR及原位杂交(ISH)进行了比较。ISPCR、PCR及ISH检测阳性率分别为44%,36%及20%。与ISH相比较,ISPCR不仅检出阳性率高,而且信号强度增强。研究结果提示,IS-PCR是诊断HCMV感染的快速、敏感、特异的实用方法。  相似文献   
996.
孕妇巨细胞病毒感染对胎儿影响的前瞻性研究   总被引:12,自引:0,他引:12  
用酶联免疫吸附试验(ELISA)及聚合酶链反应(PCR)方法对沈阳市450名孕妇进行巨细胞病毒(CMV)筛查,并前瞻性追查到其婴儿100名CMV感染状况。结果孕妇97.11%为既往感染,0.89%为原发感染,11.11%为复发感染,仅2%为易感者。450例中感染组孕妇有畸形儿3例,流产3例,其胎儿感染率与致畸率明显高于对照组。100例母婴检查结果:感染组孕妇所生先天性感染儿比对照组多1.43倍(RR=1.43),感染组有2名低智儿,对照组无。本组早孕原发感染对胎儿危害最大,其宫内传播率为33.3%。感染组孕妇9例感染儿中2例巨细胞包涵体病,7例无症状。为了早期诊断达到优生目的,对孕妇进行CMV筛查是必要的,但筛查过程中发现有活动感染时处理要慎重,最好追查到羊水阳性时考虑终止妊娠。  相似文献   
997.
鼻腔外侧壁的应用解剖   总被引:3,自引:0,他引:3  
在60个头颅(男34,女26)120侧鼻腔外侧壁上观察测量了以下诸结构,结果:上鼻甲长15.9±2.9mm,宽4.7±1.1mm;中鼻甲长36.5±3.3mm,宽10.4±3.4mm;下鼻甲长42.7±3.6mm,宽12.3±1.7mm;半月裂长16.6±2.3mm;钩突长20.7±3.1mm,宽4.3±1.7mm;筛泡长19.2±4.1mm,高6.5±2.1mm,另外还测量了前鼻棘距上述各结构的距离.  相似文献   
998.
我们利用兔抗微管蛋白抗体和兔抗辣根过氧化物酶(HRP)抗血清制备的HRP—抗HRP(PAP)复合物,建立了微管的PAP免疫酶细胞化学方法。应用此法观察到人食管癌ECa 109、胃癌SGC 7901,乳腺癌MCF 7和成骨肉瘤OS 732细胞间期胞质微管减少或消失,只有大量弥散分布的微管蛋白棕色反应产物,在微管组织中心(MTOC)附近十分密集,而正常成纤维细胞和胎儿胃粘膜上皮细胞间期,都有发达的胞质微管结构(CMTC)。在分裂期,这些肿瘤细胞都显示纺锤体微管,与正常细胞比较无明显差异。本研究应用PAP方法进一步证明,以前用免疫荧光细胞化学方法观察到的人肿瘤细胞间期胞质微管缺陷的特征。除去低温(4℃)或秋水仙酰胺处理后,解聚的CMTC又可恢复,表明本方法与免疫荧光染色法,同样具有很高的特异性。本工作在细胞固定及免疫反应的某些步骤上有所改进。  相似文献   
999.
Electrogastrogram is a surface measurement of gastric myoelectrical activity, and electrogastrography has been an attractive method for physiological and pathophysiological studies of the stomach due to its nonivasive nature. Motion artifacts, however, ruin the electrogastrogram (EGG), and make the analysis very difficult and sometimes even impossible. They must be eliminated from EGG signals before analysis. Up to now, this can only be done by visual inspection, which is not only time-consuming but also subjective. In this study, a method using feature analysis and neural networks has been developed to realize automatic detection and elimination of the motion artifacts in EGG recordings by computer. Experiments were conducted to investigate the characteristics of different motion artifacts. Useful features were extracted, and different combinations of the features used as the input of the neural network were compared to obtain the optimal performance for the detection of motion artifacts using the artificial neural network.  相似文献   
1000.
BACKGROUND: There are conflicting reports on the effect of BCG vaccination on the subsequent development of atopy and asthma. There are no data on the effects of neonatal BCG vaccination on cytokine responses of lymphocytes that are exposed in vitro to allergens. OBJECTIVES: We sought to test the hypothesis that neonatal BCG vaccination or, alternatively, evidence of an immunologic memory of this vaccination is associated with a reduced prevalence of allergic sensitization, asthma, eczema, and hay fever during childhood. METHODS: An historical cohort study was conducted among 7- to 14-year-old children who were born in 2 districts in Sydney, Australia, and whose mothers were born in southeast Asia. One district had routinely administered BCG vaccination to infants born to overseas-born mothers and the other had not. Eligible subjects were identified from birth registers. Consenting subjects completed questionnaires, performed spirometric and airway hyperresponsiveness testing, and had allergen skin prick testing and tuberculin skin testing. Blood was collected to measure total serum IgE levels and for in vitro lymphocyte culture in the presence of an extract of house dust mite, the dominant allergen in this region, and purified protein derivative of Mycobacterium tuberculosis (tuberculin). IL-4, IL-5, IL-10, and IFN-gamma were measured in the culture supernatant. RESULTS: The cohort included 309 BCG-vaccinated subjects and 442 non-BCG-vaccinated subjects. BCG-vaccinated subjects did not have a lower rate of allergic sensitization than nonvaccinated subjects. However, among the subgroup of subjects with a family history of rhinitis or eczema, BCG vaccination was associated with a lower prevalence of current asthma (defined as recent wheezing plus airway hyperresponsiveness; relative risk, 0.46; 95% CI, 0.22-0.95). BCG vaccination was also associated with lower levels of allergen-stimulated IL-10 production in vitro. Among the BCG-vaccinated subjects, the 44 (14.3%) who had tuberculin skin test reaction sizes of 5 mm or greater and the 31 (18.3%) who demonstrated an in vitro IFN-gamma response to purified protein derivative of M tuberculosis did not have lower rates of allergic sensitization and, overall, did not have a lower prevalence of allergic disease than tuberculin skin test or IFN-gamma nonreactors. CONCLUSION: We conclude that neonatal BCG vaccination has an effect on T-cell allergen responsiveness 7 to 14 years after vaccination and that among a subgroup of subjects with an inherited predisposition to allergic disease, this is associated with clinically relevant beneficial effects. The findings of this study encourage the view that external influences on the immune system in the neonatal period have consequences that extend into later childhood and influence the expression of asthma. Genetic factors are likely to modify the effect of those external factors.  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