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   387868篇
  免费   36192篇
  国内免费   24375篇
耳鼻咽喉   2928篇
儿科学   4965篇
妇产科学   4219篇
基础医学   42517篇
口腔科学   6361篇
临床医学   54437篇
内科学   52053篇
皮肤病学   4240篇
神经病学   19028篇
特种医学   14008篇
外国民族医学   224篇
外科学   34639篇
综合类   71171篇
现状与发展   86篇
一般理论   31篇
预防医学   28185篇
眼科学   10954篇
药学   41392篇
  514篇
中国医学   25339篇
肿瘤学   31144篇
  2025年   311篇
  2024年   6438篇
  2023年   7492篇
  2022年   15146篇
  2021年   19640篇
  2020年   15665篇
  2019年   12686篇
  2018年   12302篇
  2017年   11882篇
  2016年   11001篇
  2015年   16955篇
  2014年   21081篇
  2013年   19142篇
  2012年   28450篇
  2011年   31909篇
  2010年   21526篇
  2009年   17536篇
  2008年   21408篇
  2007年   21139篇
  2006年   20172篇
  2005年   19241篇
  2004年   12726篇
  2003年   12248篇
  2002年   10017篇
  2001年   8555篇
  2000年   8328篇
  1999年   8399篇
  1998年   5310篇
  1997年   5100篇
  1996年   3959篇
  1995年   3723篇
  1994年   3140篇
  1993年   2028篇
  1992年   2429篇
  1991年   2129篇
  1990年   1794篇
  1989年   1558篇
  1988年   1284篇
  1987年   1184篇
  1986年   956篇
  1985年   676篇
  1984年   370篇
  1983年   271篇
  1982年   142篇
  1981年   169篇
  1980年   118篇
  1979年   154篇
  1978年   73篇
  1977年   53篇
  1974年   42篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
The posterior wall of the upper trachea was used to make a T-E shunt. An intelligible shunt speech could thus develop two weeks postoperatively. This procedure is reliable, easy and safe, and is applicable in almost all of total laryngectomy cases. A big horizontal tuck-situated above the shunt and made of mucous membrane of the inferior pharyngeal wall and the posterior cricoid was helpful in preventing aspiration.  相似文献   
53.
54.
血液尿素氮是肾功能最重要的观测指标之一,是临床常规和急诊不可缺少的检验项目.尿素氮的测定方法,长期以来采用湿化学分析。如二乙酰—肟法,脲酶—吲哚酚法、脲酶—谷氨酸脱氢酶偶联法等.这些方法有足够的精确性和准确性,但需昂贵的仪器设备和专业技术人员,且操作繁琐又不能应急.干化学试剂以其用血微量、操作简便、快速、易于掌握和无需特殊仪器设备等优点有效地补充了湿试剂法之不足.国外已有尿素氮试纸法报道.50-93494专利技术是以脲酶、pH指示剂和屏障体组成的尿素氮试纸.此技术的特点是不用pH缓冲剂,而用多种高分子物质组成的屏障体来控制血液pH的影响.缺点是在试纸表面形成一坚硬的甲膜,使血样不易渗入试剂层,反应产生的颜色较浅,肉眼不易分辨.  相似文献   
55.
随着教育制度的改革,中职院校的学生面貌发生了巨大变化。面对新形势,我们应科学借鉴先进的教育理念,合理设置教育目标,为职业教育改革注入新的理念和活力。  相似文献   
56.
目的 提高护理质量,提高护理对象的满意度,减少医疗护理纠纷的发生。方法 产前有计划的开办孕妇学校;住院后根据个体化需要,制定标准的教育计划、优化服务环境、营造良好的人文化氛围;分娩过程中人性化护理、工休座谈会人文化的有效沟通;出院产妇送温连心卡及随访等。结果 收到良好的效果,环境的人文化管理,使护理对象感到如同家的感觉,满意度大大提高,产程的人文化实施,更体现了人性化护理。结论 产科人文化护理的实施,不但密切了护患关系,提高护理管理水平和护理质量,还使护士完善了社会形象,提高了社会地位,实现了自我价值。  相似文献   
57.
58.
This paper describes the results of the application of linear solvation energy relationships (LSERs) to quantitatively characterize the properties of adhesives and to evaluate the degree of drug-adhesive interaction in transdermal drug delivery formulations. Probe solutions were prepared in acetonitrile (ACN) for a set of probe compounds with different physicochemical properties, and were used to swell the adhesives for subsequent probe molecule-adhesive interactions. The degree of the interactions was measured by the 'sorbed' amount of probe molecules. Based on LSERs, the 'sorbed' amounts were linearly correlated with their properties. The corresponding coefficients reflect the differential interactions of these molecules with the adhesive and ACN, and are quantitative indications of the adhesive properties. Two different transdermal acrylate adhesives (isooctyl acrylate/acrylamide/vinyl acetate in the weight ratios of 75/5/20 and isooctyl acrylate/2-hydroxyethyl acrylate/vinyl acetate in the weight ratios of 58/20/18) were selected for the evaluation of the methodology. It is concluded that the first adhesive is more basic and hydrophobic, which is consistent with the use of acrylamide monomer and significant amount of isooctyl acrylate. The second adhesive is more acidic and polarizable due to a relatively high amount of the 2-hydroxyethyl acrylate. Additionally, the 'sorbed' amount can be regarded as an interaction parameter or index between a drug molecule and the adhesive. Finally, this parameter is expected to correlate with the thermodynamic properties of transdermal formulations such as drug solubility, diffusion coefficient, release rate, and maybe skin permeation rate.  相似文献   
59.
持续压力超负荷对兔左心室细胞凋亡的影响   总被引:3,自引:1,他引:2  
OBJECTIVE: To study the effect of chronic pressure overload on the apoptosis of the left ventricle myocytes in rabbits. METHODS: Rabbit models of chronic pressure overload-induced heart failure were prepared in which dynamic changes of apoptotic myocytes in the left ventricle were observed by way of terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay. RESULTS: Only a few apoptotic cells was observed in the sham-operated group, while in the experimental group, the apoptotic left ventricle myocytes significantly increased after operation, presenting a peak level between day 3 and day 7. Seven days after the operation, the apoptotic myocytes began to decrease and till day 14, the apoptotic cell number had been smaller than that measured on day 1. When signs of heart failure set in, the apoptotic myocytes were again increased (P<0.001). CONCLUSION: During chronic pressure overload, myocyte apoptosis in the left ventricle is elevated at the early stages and undulates subsequently, with the peak occurring before hypertrophy is obvious.  相似文献   
60.
Electrophysiologic target localization in posteroventral pallidotomy   总被引:1,自引:0,他引:1  
Summary The current interest in stereotactic posteroventral pallidotomy (PVP) for treating Parkinson's disease and the variability of published results have raised questions regarding techniques for target localization. In our technique the probe is guided to the optimum target at the most ventral pallidum and ansa lenticularis by macroelectrode stimulation of the internal capsule and optic tract from within the globus pallidus, with the thresholds providing a relative measure of the electrode proximity to these structures. We have characterized these localizing macroelectrode stimulation parameters in 57 posteroventral pallidotomies with consistent anatomic lesion placement, excellent outcome, and no complications.Using a 1.8 × 2.0 mm radiofrequency electrode for macroelectrode stimulation (RFG-3C, Radionics Inc.), minimum voltages (thresholds) to activate motor (at a frequency of 2 Hz) or visual (at a frequency of 100 Hz) responses as well as impedance measurements were obtained at the final target (Tf) and at distances proximal to Tf along the electrode trajectory. The visual and motor threshold voltages at Tf via our standard approach angles (50 ° above base plane, 20 ° from the sagittal plane), had a range of 1.0 to 1.5 V, and 2.0 to 3.5 V respectively. We also found that as the probe approaches Tf there is a significant decrease in voltage thresholds for motor (P<.0001) and visual (P<.0001) responses in an individual patient indicating that the probe is converging on these structures. Increases in impedance between Tf, 2–3 mm, and 4–5 mm proximal to Tf were also statistically significant (P<.0001). Microelectrode recording of electrophysiological neuronal activity at various points along the trajectory towards the target showed distinct firing patters providing identification of the globus pallidus externus and internus, ansa lenticularis, and optic tract.Macroelectrode electrophysiological stimulation within the target volume, inducing threshold responses in the internal capsule and optic tract, provides for accurate localization of the most effective PVP target in the ansa lenticularis. In unresponsive patients, the utilization of microelectrode recording for the identification of the pallidal borders and the optic tract improves safety.  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