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   68220篇
  免费   4895篇
  国内免费   2242篇
耳鼻咽喉   485篇
儿科学   1315篇
妇产科学   2924篇
基础医学   7550篇
口腔科学   1548篇
临床医学   5395篇
内科学   6650篇
皮肤病学   880篇
神经病学   4245篇
特种医学   1868篇
外国民族医学   8篇
外科学   4980篇
综合类   10913篇
现状与发展   3篇
一般理论   6篇
预防医学   6374篇
眼科学   1743篇
药学   9830篇
  81篇
中国医学   5786篇
肿瘤学   2773篇
  2024年   198篇
  2023年   981篇
  2022年   1734篇
  2021年   2424篇
  2020年   2217篇
  2019年   2109篇
  2018年   2049篇
  2017年   2092篇
  2016年   2068篇
  2015年   2005篇
  2014年   3985篇
  2013年   4875篇
  2012年   4006篇
  2011年   4483篇
  2010年   3652篇
  2009年   3254篇
  2008年   3182篇
  2007年   3302篇
  2006年   2878篇
  2005年   2574篇
  2004年   2114篇
  2003年   2069篇
  2002年   1588篇
  2001年   1492篇
  2000年   1212篇
  1999年   1145篇
  1998年   986篇
  1997年   1010篇
  1996年   903篇
  1995年   877篇
  1994年   751篇
  1993年   636篇
  1992年   588篇
  1991年   534篇
  1990年   533篇
  1989年   469篇
  1988年   348篇
  1987年   284篇
  1986年   348篇
  1985年   465篇
  1984年   442篇
  1983年   268篇
  1982年   346篇
  1981年   280篇
  1980年   306篇
  1979年   222篇
  1978年   185篇
  1977年   176篇
  1976年   162篇
  1975年   113篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
101.
Abstract. Twenty-one patients were studied at rest and during exercise after heart transplantation to compare cardiac output measured by thermodilution and impedance cardiography. Exercise was performed on a bicycle ergometer over a limited range of work load (25 and 50 watt) whilst metabolic gas exchange was recorded. One patient was studied at rest whilst his circulation was maintained by a Jarvik-7 artificial heart. The values of cardiac output measured by impedance cardiography corresponded closely with the flow rate from the artificial heart. There was also close agreement between the impedance and thermodilution measurements of cardiac output at rest and during exercise. Both measurements followed the changes in heart rate and oxygen consumption. Both thermodilution and impedance cardiography methods elicited good reproducibility of cardiac output measurements at rest and during exercise. These observations suggest that the noninvasive and continuous record of cardiac output obtained by impedance cardiography can be used for the postoperative monitoring of heart transplant recipients.  相似文献   
102.
石刻雕塑作业劳动卫生学调查及实验研究   总被引:1,自引:0,他引:1  
测定了石雕作业粉尘浓度,几何平均浓度为82.35~3.67mg/m3。工人职业性健康检查结果,接尘工人的咽部充血、咳嗽、咯痰检出率高于对照组;肺功能低下的检出率也高于对照组。该厂自1972年以来发生尘肺患者17例,其病情发展和晋期缓慢,发病工龄长。动物实验研究表明,石雕粉尘有轻微的致纤维化作用。  相似文献   
103.
Summary Pleiotrophin (PTN), also known as HBGAM, belongs to an emerging cytokine family unrelated to other growth factors. We report here the first comprehensive study using in situ hybridization on the cellular distribution of this new heparin-binding growth factor mRNA in rat tissues. PTN mRNA was developmentally expressed in many — but not all — neuroectodermal and mesodermal lineages, whilst no PTN mRNA was detected in endoderm, ectoderm and trophoblast. PTN mRNA was found in the nervous system throughout development, with a post-natal peak of expression. In the adult nervous system, significant expression persisted in hippocampal CA1 pyramidal neurons and in cortical neurons, but also in different non-neuronal cells types in various locations (olfactory nerve, cerebellar astrocytes, pituicytes, Schwann cells surrounding the neurons in sensory ganglia). PTN mRNA was also found during development in the mesenchyme of lung, gut, kidney and reproductive tract, in bone and cartilage progenitors, in dental pulp, in myoblasts, and in several other sites. Expression was differently regulated in each location, but usually faded around birth. In the adult, PTN mRNA was still present in the meninges, the iris, the Leydig cells of the testis and in the uterus. PTN mRNA was also strongly expressed in the basal layers of the tongue epithelium, which is the only epithelium and ectodermal derivative to express PTN mRNA, and this only after birth. PTN is known to be a growth factor for perinatal brain neurons and a mitogen for fibroblasts in vitro. Recently, trophic effects on epithelial cells and a role as a tumour growth factor have been reported. The mechanisms of regulation and the functions of PTN are however still uncertain. Its expression pattern during development suggests important roles in growth and differentiation. Moreover, the presence of PTN mRNA in several adult tissues and the up-regulation of PTN mRNA expression in the gravid uterus indicate that PTN also has physiological functions during adulthood.  相似文献   
104.
Although relatively high CO2 laser energies have been shown to sterilize root canals, the response of several bacterial strains to decreasing exposures of CO2 laser energy remains unknown. Freshly grown bacterial cells were irradiated on glass microscope coverslips. A comparison of equivalent energy exposures with differing parameters was made on the bacterial viability. No statistically significant difference was found in the energy required to kill closely related bacterial species. However, the energy density required to kill greater than 99.5% of the bacteria is less than 200 J/cm2, much less than that shown to sterilize in a previous study.  相似文献   
105.
Treatment of rat heart grafts with PUVA, the combination of the photosensitizer 8-methoxypsoralen and longwave ultraviolet light, leads to a prolonged transplant survival in allogeneic recipients. A PUVA treatment of the recipient rats, performed for 7 consecutive days after transplantation, prolonged graft survival even more effectively. This may be due to the systemic immunomodulatory effects of PUVA in the recipient. One of the mediators is urocanic acid, which is transformed by ultraviolet light in the skin from its trans- to the cis-isomer, which, in turn, acts as a mediator on the immune system. An injection of cisurocanic acid into graft recipients for 7 consecutive days after transplantation resulted in prolonged graft survival; in 40% of the rats, permanent graft acceptance was observed. The significance of these results for clinical organ transplantation is discussed.  相似文献   
106.
运用人力资源管理策略 改革病房护理管理   总被引:3,自引:0,他引:3  
从发展成功管理的共同文化,创建优质服务病房;建立有效的护理人力资源管理支持系统,创建适合于专业护理的工作环境,确保护理质量;以病人为中心,以病人满意度作为衡量护理工作优劣的标准三个方面介绍了乐山市人民医院运用护理人力资源管理策略,改革病房护理管理,创建优质服务病房的实践经验及其效果。  相似文献   
107.
真皮下血管网岛状皮瓣抗菌力的实验研究   总被引:2,自引:0,他引:2  
为研究真皮下血管网薄皮瓣用于感染创面的可行性,在家猪臀部两侧分别形成以旋髂深血管主干分支为蒂的传统岛状皮瓣和远侧50%修薄的真皮下血管网岛状皮瓣。用细菌计数、吖啶橙荧光染色测定白细胞吞噬指数和白细胞内杀菌率,应用激光多普勒、墨汁灌注、透明标本等方法,对两种皮瓣的抗菌力作自身对照研究。结果表明,真皮下血管网岛状皮瓣的抗菌力明显降低,可能与皮瓣修薄后血供减少,白细胞功能相应降低有关。  相似文献   
108.
应用原位杂交技术,观察了二乙基亚硝胺(DEN)诱发大鼠肝癌前病变组织中胎盘型谷胱甘肽S转移酶(GST-P)mRNA的表达。结果显示,GST-PmRNA主要在癌前病变肝组织中的变异灶及灶外卵圆形细胞内表达,且在变异灶间或和同一灶内阳性细胞间表达程度不尽一致,而正常肝、再生肝组织中未见其表达。提示在分子水平上变异灶细胞及卵圆型细胞可能成为实验性肝癌的癌前期细胞  相似文献   
109.
The release of lithium carbonate incorporated into polymethylmethacrylate, poly vinyl chloride, hy-drogenated vegetable oil, and carbomer matrix tablets was studied in vitro. The formulation containing 10% carbomer showed a sustained-release profile comparable to that of a standard, commercially available, sustained-release preparation containing 400 mg lithium carbonate embedded in a composite material. In vivo the newly formulated and standard sustained-release lithium carbonate tablets were compared to an oral solution and conventional lithium carbonate tablets in 12 healthy subjects. These crossover studies showed that the sustained-release tablets produced a flatter serum concentration curve than the oral solution and conventional tablet, without loss of total bioavailability.  相似文献   
110.
碘过量与甲状腺疾病   总被引:8,自引:0,他引:8  
介绍近年来国内外对高碘致甲状腺肿、甲状腺功能亢进症、甲状腺功能减退症、自身免疫甲状腺炎、甲状腺癌的研究进展,阐述防治碘缺乏病(IDD)应当因地因人分类设计,盲目补碘和过度补碘都是错误的。  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