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   32747篇
  免费   1686篇
  国内免费   790篇
耳鼻咽喉   396篇
儿科学   681篇
妇产科学   1167篇
基础医学   8150篇
口腔科学   779篇
临床医学   2170篇
内科学   3568篇
皮肤病学   560篇
神经病学   1973篇
特种医学   721篇
外科学   1958篇
综合类   3478篇
预防医学   3606篇
眼科学   462篇
药学   3357篇
  6篇
中国医学   386篇
肿瘤学   1805篇
  2023年   301篇
  2022年   558篇
  2021年   813篇
  2020年   799篇
  2019年   789篇
  2018年   817篇
  2017年   897篇
  2016年   879篇
  2015年   1016篇
  2014年   1836篇
  2013年   1916篇
  2012年   1650篇
  2011年   2039篇
  2010年   1589篇
  2009年   1623篇
  2008年   1701篇
  2007年   1563篇
  2006年   1394篇
  2005年   1203篇
  2004年   1066篇
  2003年   978篇
  2002年   696篇
  2001年   698篇
  2000年   666篇
  1999年   600篇
  1998年   593篇
  1997年   562篇
  1996年   573篇
  1995年   586篇
  1994年   553篇
  1993年   466篇
  1992年   446篇
  1991年   378篇
  1990年   337篇
  1989年   304篇
  1988年   286篇
  1987年   226篇
  1986年   180篇
  1985年   269篇
  1984年   251篇
  1983年   154篇
  1982年   155篇
  1981年   140篇
  1980年   126篇
  1979年   114篇
  1978年   87篇
  1977年   72篇
  1976年   66篇
  1974年   42篇
  1973年   37篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
目的 探讨血清β-绒毛膜促性腺激素(β-hCG)和C-反应蛋白(CRP)水平,在预测胎膜早破宫内感染和预后的应用比较.方法 入选2009年3月-2011年5月在医院妇产科孕足月住院发生胎膜早破的孕妇146例,产前抽取静脉血5 ml,用免疫分析法分别检测血清β-hCG和CRP,产后留取胎膜组织和胎盘组织,检查是否存在组织绒毛膜炎,将146例胎膜早破孕妇分为感染组与非感染组,比较两组血清β-hCG和CRP,以评价β-hCG、CRP在预测胎膜早破宫内感染和预后中的临床价值.结果 146例胎膜早破孕妇中,血清β-hCG阳性者47例,发生感染33例,感染率为70.2%,阴性者99例,发生感染19例,感染率为19.2% ;CRP阳性者63例,发生感染41例,感染率为65.1%;阴性者83例,发生感染11例,感染率为13.3%,差异均有统计学意义(P<0.05),血清β-hCG预测胎膜早破感染敏感度为63.5%,特异度为85.1%,二者与CRP检查差异无统计学意义,146例胎膜早破的孕妇分娩顺利,血清β-hCG和CRP阳性者预后较阴性者差,抗菌药物使用时间长,剂量大,住院时间延长,但是血清β-hCG和CRP在评价预后无差异.结论 血清β-hCG和CRP均能较好地预测胎膜早破孕妇是否发生感染和评价预后,二者之间没有差异,临床上结合血清β-hCG和CRP能够更迅速、更准确地诊断胎膜早破并发感染,并能更好地评价预后.  相似文献   
993.
锶与人体健康   总被引:1,自引:0,他引:1  
锶是人体中必需微量元素之一,它与人体骨骼的形成密切相关,是骨骼、牙齿的主要成分,身体所有组织中都有锶,在肠内它与钠竞争吸收部位,使人体降低对钠的吸收,有利于心血管正常活动。锶可用来治疗一些由于副甲状腺功能不全导致的抽搐症状,缺锶会引起龋齿,锶过量则可引起骨骼的生长发育过快,表现为关节和骨骼变形、粗大、脆弱、疼痛,肌肉萎缩及贫血等。  相似文献   
994.
Infection with Bartonella spp may cause cardiac arrhythmias, myocarditis and endocarditis in humans. The aim of the present study was to evaluate a possible association between Bartonella spp bacteremia and endocarditis, arrhythmia and Chagas cardiomyopathy in patients from Brazil and Argentina. We screened for the presence of bacterial 16S rRNA in human blood by PCR using oligonucleotides to amplify a 185-bp bacterial DNA fragment. Blood samples were taken from four groups of subjects in Brazil and Argentina: i) control patients without clinical disease, ii) patients with negative blood-culture endocarditis, iii) patients with arrhythmias, and iv) patients with chronic Chagas cardiomyopathy. PCR products were analyzed on 1.5% agarose gel to visualize the 185-bp fragment and then sequenced to confirm the identity of DNA. Sixty of 148 patients (40.5%) with cardiac disease and 1 of 56 subjects (1.8%) from the control group presented positive PCR amplification for Bartonella spp, suggesting a positive association of the bacteria with these diseases. Separate analysis of the four groups showed that the risk of a Brazilian patient with endocarditis being infected with Bartonella was 22 times higher than in the controls. In arrhythmic patients, the prevalence of infection was 45 times higher when compared to the same controls and 40 times higher for patients with Chagas cardiomyopathy. To the best of our knowledge this is the first report of the association between Bartonella spp bacteremia and Chagas disease. The present data may be useful for epidemiological and prevention studies in Brazil and Argentina.  相似文献   
995.
目的:分析高危型人乳头瘤病毒(HPV)感染者配偶的病毒感染状况并调查其危险因素。方法:对146例妻子确定为高危型HPV阳性的已婚男性进行阴茎头和尿道口上皮细胞高危型HPV型别检测,并通过问卷调查收集感染者配偶的人口学信息,分析发生病毒感染的可能危险因素。结果:146例男性共检出高危型HPV感染64例,感染率为43.84%,优势型别为HPV16、18、58、52型。多个性伴侣(≥2)、性生活前后不经常清洗外阴、包皮过长或包茎、患包皮阴茎头炎是感染者配偶高危型HPV感染的危险因素(P0.05或P0.01)。结论:女性高危型HPV感染者的配偶也是高危型HPV感染的高危人群,男性在性活动中洁身自好、保持良好的性行为方式和尽早治疗包皮过长、包茎、包皮阴茎头炎可能有利于减少病毒在配偶之间的相互传播。  相似文献   
996.
997.
Background: Food intake, accompanied by systemic and splanchnic haemodynamic changes, has only been studied in males. The extent to which splanchnic postprandial hyperaemia shows gender differences is unknown. Methods: We tested 1) the splanchnic hyperaemic response to food in females and 2) whether postprandial haemodynamic changes show gender differences. Twenty-four healthy women (aged 20-35 years) and 20 healthy men (aged 21-34 years) participated in the study. A liquid test meal (Ensure plus, 1.5 kcal/ml) was perfused intraduodenally for 75 min through an enteral feeding tube at a rate of 3 ml/min after a 45-min basal period. Blood flow parameters were measured using Echo-Doppler technology. Results: Basal diastolic arterial blood pressure was significantly (P  相似文献   
998.
During the immune response to pathogens and autoantigens, CD8T cells are exposed to numerous inflammatory agents including the cytokine IL-12. Previous studies have focused on how IL-12 regulates T cell functions when present during or after the activation of the T cell receptor (TCR). However, recent studies suggest that prior exposure to IL-12 also alters the TCR responsiveness of murine T cells. Whether similar phenomena occur in human activated CD8T cells and the mechanisms mediating these effects remain unexplored. In this study, we observed that pretreatment of human activated CD8T cells with IL-12 results in increased cytokine mRNA and protein production following subsequent TCR challenge. The potentiation of TCR-mediated cytokine release was transient and required low doses of IL-12 for at least 24 h. Mechanistically, prior exposure to IL-12 increased the TCR induced activation of select MAPKs and AKT without altering the activation of more proximal TCR signaling molecules, suggesting that the IL-12 mediated changes in TCR signaling are responsible for the increased production of cytokines. Our data suggest that prior treatment with IL-12 potentiates human CD8T cell responses at sites of infection and inflammation, expanding our understanding of the function of this clinically important cytokine.  相似文献   
999.

Introduction  

Preconception diagnosis requires first polar body biopsy. When the hole in the zona pellucida is made with a laser beam, heat propagation could, like the biopsy itself, be deleterious. Our aim was to evaluate the effect of this technique on human in vitro matured oocyte and embryo development.  相似文献   
1000.
Gender differences in medicine have been recognized in anatomy, physiology, as well as in epidemiology and manifestations of various diseases. With respect to skin disorders, males are generally more commonly afflicted with infectious diseases while women are more susceptible to psychosomatic problems, pigmentary disorders, certain hair diseases, and particularly autoimmune as well as allergic diseases. Significantly, more female sex‐associated dermatoses can be identified than the male sex‐associated dermatoses. Dermatoses in the genital area differ between men and women. Gender differences also exist in the occurrence and prognosis of certain skin malignancies. The mechanisms underlying gender differences in skin diseases remain largely unknown. Differences in the skin structure and physiology, effect of sex hormones, ethnic background, sociocultural behaviour and environmental factors may interact to exert the influences. A better understanding of gender differences in human health and diseases will allow the development of novel concepts for prevention, diagnosis and therapy of skin diseases.  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