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   5137篇
  免费   284篇
  国内免费   96篇
耳鼻咽喉   42篇
儿科学   60篇
妇产科学   64篇
基础医学   659篇
口腔科学   151篇
临床医学   742篇
内科学   409篇
皮肤病学   33篇
神经病学   335篇
特种医学   199篇
外科学   659篇
综合类   679篇
预防医学   841篇
眼科学   109篇
药学   291篇
  12篇
中国医学   125篇
肿瘤学   107篇
  2024年   14篇
  2023年   109篇
  2022年   217篇
  2021年   316篇
  2020年   270篇
  2019年   238篇
  2018年   244篇
  2017年   195篇
  2016年   137篇
  2015年   167篇
  2014年   428篇
  2013年   366篇
  2012年   360篇
  2011年   337篇
  2010年   260篇
  2009年   241篇
  2008年   218篇
  2007年   188篇
  2006年   181篇
  2005年   147篇
  2004年   113篇
  2003年   80篇
  2002年   77篇
  2001年   66篇
  2000年   46篇
  1999年   54篇
  1998年   43篇
  1997年   46篇
  1996年   35篇
  1995年   25篇
  1994年   37篇
  1993年   25篇
  1992年   18篇
  1991年   18篇
  1990年   17篇
  1989年   7篇
  1988年   12篇
  1987年   9篇
  1986年   11篇
  1985年   17篇
  1984年   25篇
  1983年   17篇
  1982年   18篇
  1981年   15篇
  1980年   21篇
  1979年   8篇
  1978年   6篇
  1977年   3篇
  1976年   7篇
  1973年   2篇
排序方式: 共有5517条查询结果,搜索用时 9 毫秒
11.
选用典型的清热中药黄芩、银花、连翘组成清热方,从体温调节中枢神经介质方面来探讨清热类中药的解热作用机制。实验表明影响体温调节中枢解热介质AVP代谢,增加其含量,从而抑制体温调定点上移是清热中药作用机理之一。  相似文献   
12.
SRTR Center-Specific Reporting Tools: Posttransplant Outcomes   总被引:3,自引:2,他引:1  
Measuring and monitoring performance—be it waiting list and posttransplant outcomes by a transplant center, or organ donation success by an organ procurement organization and its partnering hospitals—is an important component of ensuring good care for people with end-stage organ failure. Many parties have an interest in examining these outcomes, from patients and their families to payers such as insurance companies or the Centers for Medicare and Medicaid Services; from primary caregivers providing patient counseling to government agencies charged with protecting patients.
The Scientific Registry of Transplant Recipients produces regular, public reports on the performance of transplant centers and organ procurement organizations. This article explains the statistical tools used to prepare these reports, with a focus on graft survival and patient survival rates of transplant centers—especially the methods used to fairly and usefully compare outcomes of centers that serve different populations. The article concludes with a practical application of these statistics—their use in screening transplant center performance to identify centers that may need remedial action by the OPTN/UNOS Membership and Professional Standards Committee.  相似文献   
13.
目的 采用脑磁图(magnetoencephalograph,MEG)的等价电流偶极子定位法(Equivalent current dipole,ECD)和合成孔径磁场定位法(SAMSynthetic、Aperture Magnetometry,SAM)定位母语为汉语的健康自愿者的语占中枢,探讨汉字的语言处理过程。方法 对10例母语为汉语的健康受试者给予默读真词、假词的语言任务刺激,记录刺激后产生的诱发磁场,将采集的数据与MRI叠加获得磁源性影像(MSI Magnetic source imaging)语占功能区定位川同样的方法对4例胶质瘤患者进行术前语言功能区定位,术中皮层电刺激所定位语言功能区,明确是否产生言语障碍。结果 所有受试者真词、假词均在双侧大脑半球诱发出明显的晚期磁反应波,左侧大脑半球磁反应波分化较右侧大脑半球好,Broea区俯于额下回后部,Wernicke区位于颞中同、颢上回、缘上回,Wernieke区先于Broca区出现。胶质瘤患者术巾电刺激所定位的Broca区、Wernicke区均产生言语障碍:结论母语为汉语的正常人的Broca区Wernieke区与经典的语言中枢糕本相符,MEG定位语言中枢的技术是可行的。  相似文献   
14.
Although extensively pursued, the central respiratory neurons have remained elusive. We departed from the more conventional physiologic and morphologic methods of system and tissue examination and cultured dissociated fetal rat cells (Fitzgerald et al., J Neurosci Res 33:579-589, 1992) from the area of the nucleus ambiguus and the nucleus tractus solitarius located within the 2 mm rostral to the obex. Pacemaker-like cells, with a regular single or bursting activity, studied at 3-5 weeks of age, responded to very small pulses of CO2 (50 ms) and low pH with an increase in spike frequency and a decrease in spike amplitude. Other irregularly beating or silent cells did not respond or else required very large pulses (> 200 ms) to do so. The pacemaker cells also responded to hypoxia induced by administration of sodium hydrosulfite with an increase in spike frequency and amplitude; high oxygen (> 600 torr) and adenosine produced a decrease in electrical activity. Most of these cells were multipolar after staining with antibodies to neuron-specific enolase (NSE) and Fragment C of tetanus toxin. They did not stain for choline acetyltransferase (ChAT). The results suggest that these cultured cells, expressing a phenotype inherently responsive to CO2 and low pH, have the characteristics of central respiratory chemoreceptors, and may be involved in the generation of the respiratory rhythm.  相似文献   
15.
在急救中心开展多发伤一体化救治分析   总被引:16,自引:5,他引:11  
目的 探讨提高多发伤救治成功率的措施。方法 回顾性总结2002年6月~2003年6月间中山市急救中心开展多发伤救治的效果,分析多发伤一体化救治的模式和关键点。结果 共收治135例,抢救成功107例,成功率79.3%;死亡28例,死亡率20.7%。结论 (1)住急救中心实施多发伤一体化救治是提高其成功率的有效途径,也是多发伤救治的发展趋势,(2)在急救中心实施多发伤一体化救治的模式:急救中心设立创伤中心、建立成套的创伤急救体系,培养高素质专业人员.多发伤的诊治由急救中心医师实施或组织实施。(3)严重多发伤救治的关键点:抓好院前、院内急救——抢救生命;开展急诊手术——尽早修复损伤器官,消除致死致残因素;重视重症监护及治疗——进一步治疗原发损伤,保护各脏器功能,促进机体恢复,防止并发症。  相似文献   
16.
Mice rendered deficient for interleukin (IL) 6 by gene targeting were evaluated for their response to T cell–dependent antigens. Antigen-specific immunoglobulin (Ig)M levels were unaffected whereas all IgG isotypes showed varying degrees of alteration. Germinal center reactions occurred but remained physically smaller in comparison to those in the wild-type mice. This concurred with the observations that molecules involved in initial signaling events leading to germinal center formation were not altered (e.g., B7.2, CD40 and tumor necrosis factor R1). T cell priming was not impaired nor was a gross imbalance of T helper cell (Th) 1 versus Th2 cytokines observed. However, B7.1 molecules, absent from wild-type counterparts, were detected on germinal center B cells isolated from the deficient mice suggesting a modification of costimulatory signaling. A second alteration involved impaired de novo synthesis of C3 both in serum and germinal center cells from IL-6–deficient mice. Indeed, C3 provided an essential stimulatory signal for wild-type germinal center cells as both monoclonal antibodies that interrupted C3-CD21 interactions and sheep anti–mouse C3 antibodies caused a significant decrease in antigen-specific antibody production. In addition, germinal center cells isolated from C3–deficient mice produced a similar defect in isotype production. Low density cells with dendritic morphology were the local source of IL-6 and not the germinal center lymphocytes. Adding IL-6 in vitro to IL-6–deficient germinal center cells stimulated cell cycle progression and increased levels of antibody production. These findings reveal that the germinal center produces and uses molecules of the innate immune system, evolutionarily pirating them in order to optimally generate high affinity antibody responses.  相似文献   
17.
The distribution of the specific radioactivity and the incorporation into protein of [3H]-tryptophan and [3H]valine at varying layers from surface to centre were measured in incubated slices of cerebral cortices from infant and adult rats. Specific radioactivity in free amino acids was in both age groups highest in the intact surface layer. Incorporation of tryptophan into protein was even in slices from adult rats but much less than the average in the surface layers in slices from infant rats. Incorporation of valine exhibited similar heterogeneity in both age groups. The results suggest in brain slice preparations a zonal compartmentation of amino acid and protein metabolism which varies for different amino acids.  相似文献   
18.
19.
Axial rotation component of thoracic scoliosis   总被引:3,自引:0,他引:3  
The axial rotation (rotation about a vertical axis) of the vertebrae, of the ribs, and of the back surface are components of the deformity recognized clinically as the "rib hump" in thoracic scoliosis. Relationships of these rotations to the lateral deviation and lateral curvature of the spine were studied in 40 patients with idiopathic scoliosis. Stereoradiographs of the spine and rib cage were used to measure three components of axial rotation: rotation of the vertebrae, of the rib cage, and of the plane of maximum curvature of the spine. Stereotopographs of the back surface were digitized to measure the axial rotation of the back surface. In individual patients, there were high correlations of all components of axial rotation at each spinal level with the corresponding vertebral lateral deviation from the spinal axis. By regression analyses of the maximum values of each rotation in each curve, the rotation of the apex vertebra was found to be generally of lesser magnitude than the rotation of the plane of maximum curvature of the spine and in an opposite sense in kyphotic curves. The rib cage rotation was generally of lesser magnitude than the vertebra rotation, and the back surface rotation was less than both of these skeletal rotations. Vertebra rotation correlated most closely with lateral deviation of the spine. Simple segmental coupling of axial rotation and lateral bending could not be responsible for this axial rotation.  相似文献   
20.
Summary Genomic imprinting is a biological phenomenon determined by an evolutionally acquired, underlying system that may control harmonious development and growth in mammals. It is also relevant to some genetic disorders in man. In this article, lines of biological evidence of imprinting, characteristics of the mouse and human imprinted genes, and findings and mechanisms on the occurrence of several human imprinting disorders are reviewed.  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