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   1587篇
  免费   109篇
  国内免费   21篇
耳鼻咽喉   9篇
儿科学   22篇
妇产科学   12篇
基础医学   364篇
口腔科学   29篇
临床医学   166篇
内科学   165篇
皮肤病学   67篇
神经病学   246篇
特种医学   26篇
外科学   72篇
综合类   85篇
一般理论   1篇
预防医学   247篇
眼科学   25篇
药学   104篇
中国医学   37篇
肿瘤学   40篇
  2023年   16篇
  2022年   25篇
  2021年   65篇
  2020年   56篇
  2019年   54篇
  2018年   73篇
  2017年   55篇
  2016年   72篇
  2015年   50篇
  2014年   68篇
  2013年   137篇
  2012年   77篇
  2011年   83篇
  2010年   74篇
  2009年   75篇
  2008年   75篇
  2007年   77篇
  2006年   69篇
  2005年   52篇
  2004年   44篇
  2003年   37篇
  2002年   32篇
  2001年   27篇
  2000年   30篇
  1999年   32篇
  1998年   15篇
  1997年   13篇
  1996年   9篇
  1995年   16篇
  1994年   13篇
  1993年   9篇
  1992年   17篇
  1991年   14篇
  1990年   13篇
  1989年   12篇
  1988年   8篇
  1987年   12篇
  1986年   10篇
  1985年   10篇
  1984年   14篇
  1983年   6篇
  1982年   9篇
  1981年   10篇
  1980年   6篇
  1979年   8篇
  1978年   6篇
  1977年   4篇
  1976年   7篇
  1975年   8篇
  1973年   5篇
排序方式: 共有1717条查询结果,搜索用时 31 毫秒
1.
2.
Recently, there has been a call for research-informed and research-developed practice in health sciences education. This prompts the consideration of alternative suitable research approaches that could be used to enhance health sciences education practice, including medical radiation sciences education (MRSE) practice. In this discussion paper, the authors uphold design science research (DSR) methodology as a suitable research approach to enhance MRSE practice and research. An overview of the DSR methodology and an example of a project that used DSR methodology are presented to demonstrate the application of this methodology in MRSE practice and research. The paper concludes that the use of DSR methodology could be instrumental in addressing practice related challenges while developing a theoretical contribution to the discipline.  相似文献   
3.
目的分析犬梭形动脉瘤(FFA)模型在采用生物膜包裹后1年期的血流动力学与组织学变化,探讨生物膜包裹的远期效果。方法对10只犬采用显微手术制作双侧梭形动脉瘤模型20枚。左侧用生物膜完全匹配包裹。右侧未包裹以作为对照,行DSA、彩色多普勒超声动态检测,对照观察两组的血流动力学变化特征。术后1年时行活体解剖取标本。对照观察组织学变化。结果所有模型均制作成功。FFA腔内为涡流,多普勒超声具有特征性的双相涡流频谱,造影剂滞留明显;对照侧术后1年膨胀性增大,并具有自发破裂的趋势。手术侧包裹后瘤腔消失。血流恢复为层流,超声频谱与颈总动脉一致,未见造影剂滞留,血管顺应性、弹性及舒缩状态与颈总动脉基本匹配;瘤腔与吻合口处的血流动力学参数差异有统计学意义(P〈0.05)。组织学改变与血流动力学变化相符。结论犬FFA模型是研究包裹治疗的理想动脉模型,采用生物膜完全匹配包裹,远期效果良好。  相似文献   
4.
Stress is a general reaction to any burden on the body. If such a process becomes chronic, stress-based diseases develop which are hard to treat. The stress cycle in the hypothalamus-hypophysis-suprarenal glands disturbs the bio-psycho-social circuit, which is in a feedback loop with controlled and uncontrolled stress converting processes. This is coupled with the reactivity of the extracellular matrix (ECM) embedded in this circuit. Two “breaks” are installed in the ECM to keep stress reactions under control: The non neuronal acetylcholin system (NNAChS) and the system of endogenous endocannabinoids. Both systems have a limiting effect on pathological increased sympathetic effects raised by stress. Acupuncture stimulates the parasympathicus and NNAChS while neural therapy augments the endocannabinoid system, resulting in slower sympathetic actions.  相似文献   
5.
目的 分析富含三酰甘油脂蛋白(TRLs)分子组成及其代谢特征.方法应用脂蛋白电泳技术,对30例飞行员空腹和脂肪负荷餐后血浆做脂蛋白分析,以扫描图面积表示各亚组分构成,观察脂蛋白亚组分变化特点.结果 30例飞行员TRLs清除延迟发生率46.67%.TRLs分子脂蛋白亚组分由极低密度脂蛋白(VLDL)、中密度脂蛋白(IDL)、低密度脂蛋白(LDL)、乳糜微粒(CM)和脂蛋白a[LP(a)]组成.TRLs清除延迟典型扫描图特征为LDL左侧区面积增高,呈双峰或多峰.LDL、VLDL区面积增高,伴有高密度脂蛋白(HDL)面积降低.结论 高三酰甘油血症致动脉粥样硬化作用是在代谢水平异常所致的TRLs清除延迟,TRLs清除延迟是核心环节.  相似文献   
6.
Semiconductor manufacturing: an introduction to processes and hazards   总被引:2,自引:0,他引:2  
Recent studies suggest that semiconductor workers have an increased incidence of work-related illness. Semiconductor manufacturing is a chemically intensive industry involving many potentially hazardous operations. As this industry moves into new geographic areas, health care professionals will be asked to evaluate medical or workplace conditions associated with unfamiliar and complex production processes. This paper provides an overview of semiconductor manufacturing processes for these health practitioners. Each step of device fabrication is detailed with its attendant chemical and physical hazards. Broader concepts of industrial control technology, clean room ventilation, and ergonomics are explained. The hazards are tabulated to allow rapid assessment of the risks inherent to each processing step. References have been chosen to guide the reader to more indepth information.  相似文献   
7.
The problem of designing strategies for optimal feedback control of non‐linear processes, specially for regulation and set‐point changing, is attacked in this paper. A novel procedure based on the Hamiltonian equations associated to a bilinear approximation of the dynamics and a quadratic cost is presented. The usual boundary‐value situation for the coupled state–costate system is transformed into an initial‐value problem through the solution of a generalized algebraic Riccati equation. This allows to integrate the Hamiltonian equations on‐line, and to construct the feedback law by using the costate solution trajectory. Results are shown applied to a classical non‐linear chemical reactor model, and compared against suboptimal bilinear‐quadratic strategies based on power series expansions. Since state variables calculated from Hamiltonian equations may differ from the values of physical states, the proposed control strategy is suboptimal with respect to the original plant. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
8.
嗅神经母细胞瘤的临床病理及超微结构观察   总被引:2,自引:0,他引:2  
本文报道了12例嗅神经母细胞瘤的临床病理及其中2例的超微结构特点。光镜观察结果,12例均可见细胞之间由细胞突起形成的嗜酸性背景,有4例可见Flexner菊形团、7例见Homer-Wright菊形团(其中3例同时存在Flexner菊形团);电镜观察结果,细胞具有轴突样和树突样突起,胞体及突起内含微管、神经细丝及神经分泌颗粒,细胞突起之间见突触样的连接。作者并对该瘤的诊断问题进行了探讨。  相似文献   
9.
Glial fibrillary acidic protein (GFAP) is the principal intermediate filament protein found in mature astrocytes. Although the exact function of GFAP is poorly understood, it is presumed to stabilize the astrocyte’s cytoskeleton and help in maintaining cell shape. Previous studies from our laboratory have shown that when astrocytes were cocultured with primary Schwann cells (pSCs), astrocytes became hypertrophied and fibrous with intensely positive GFAP staining and segregated Schwann cells (SCs) into pockets. In order to understand the functional role of GFAP in this already established astrocyte-SC coculture model, we generated GFAP-negative cell lines from a GFAP-positive astrocytoma cell line and cocultured both the cell lines with pSCs. Our studies demonstrate that the GFAP-positive cell line put out processes toward the SCs, whereas the GFAP-negative cells did not form processes and the majority of the cells remained round. The most significant and interesting finding of this study, however, is the formation of elaborate processes by SCs when grown in coculture with the astrocytoma cells, unlike SCs cultured alone, which showed their typical bipolar spindle-shaped morphology. The extent of processes did not seem to be dependent on GFAP, since SCs cultured with both the cell lines formed similar processes. This coculture model may be useful in elucidating the factor(s) responsible for the formation of processes by SCs and can be further help in our understanding of the mechanism of morphological transformation of SCs.  相似文献   
10.
随着我国老龄化进程的进一步加剧,衰弱作为常见的老年综合征已成为备受关注的公共卫生问题。高血压与衰弱常共存于老年人,导致出现多种不良健康结局。本文分析了老年高血压相关性衰弱的流行现状及发病机制,包括炎性反应、氧化应激反应、胰岛素抵抗及激素代谢紊乱等,总结了运动干预改善高血压相关性衰弱的可能作用途径,并发现目前关于高血压相关性衰弱的运动作用机制类研究仍然缺乏,而且不同类型的运动干预形式对机体的作用机制也存在一定差异性,未来可以进一步探讨不同的运动干预形式对高血压相关性衰弱的作用靶点及干预效果的不同。  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