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   1591篇
  免费   182篇
  国内免费   24篇
耳鼻咽喉   6篇
儿科学   8篇
妇产科学   14篇
基础医学   138篇
口腔科学   10篇
临床医学   248篇
内科学   66篇
皮肤病学   7篇
神经病学   56篇
特种医学   22篇
外科学   49篇
综合类   265篇
预防医学   444篇
眼科学   4篇
药学   316篇
  1篇
中国医学   120篇
肿瘤学   23篇
  2024年   8篇
  2023年   35篇
  2022年   77篇
  2021年   70篇
  2020年   82篇
  2019年   66篇
  2018年   75篇
  2017年   49篇
  2016年   46篇
  2015年   70篇
  2014年   163篇
  2013年   158篇
  2012年   145篇
  2011年   157篇
  2010年   108篇
  2009年   81篇
  2008年   76篇
  2007年   85篇
  2006年   57篇
  2005年   34篇
  2004年   29篇
  2003年   21篇
  2002年   12篇
  2001年   15篇
  2000年   11篇
  1999年   9篇
  1998年   11篇
  1997年   6篇
  1995年   5篇
  1994年   4篇
  1993年   3篇
  1992年   3篇
  1991年   6篇
  1990年   2篇
  1989年   1篇
  1988年   2篇
  1987年   1篇
  1985年   2篇
  1984年   2篇
  1981年   1篇
  1979年   1篇
  1975年   1篇
  1974年   1篇
  1973年   1篇
  1972年   3篇
  1971年   1篇
  1964年   1篇
排序方式: 共有1797条查询结果,搜索用时 15 毫秒
1.
目的:优选散结消肿贴中大黄、重楼的渗漉提取工艺。方法:以总固体物得率和总蒽醌得率为指标,用正交实验优选。结果:工艺中影响最大的因素是乙醇浓度,其次是乙醇用量,浸泡时间影响较小。最佳工艺条件为乙醇浓度65%,乙醇用量8倍量。浸泡时间24h。结论:渗漉法操作简单,成份破坏少,用优选所得条件进行提取,总蒽醌和总固体物得率均较高,优选结果可用于散结消肿贴中大黄、重楼的提取。  相似文献   
2.
在系统水平上研究人脑的睡眠过渡过程,以寻求监测睡眠过渡过程的新方法.方法:让15名睡眠良好者进行睡眠中的行为反应实验,获取行为反应量.结果:发现行为反应量与脑电图所反映的脑状态一致,且能反应睡眠过渡过程中脑状态的微小变化.结论:以行为反应量监测睡眠过渡过程,结果可靠,操作简便,对被试者干扰小.  相似文献   
3.
4.
周小兵 《中外医疗》2009,28(34):185-185
目的吸取误诊教训,提高对茎突综合征诊断水平。方法回顾性分析3例茎突综合征误诊的临床资料。结果找出误诊原因,并借助文献进行分析、讨论。结论要熟悉茎突综合征的病因,临床特点和并发症,提高警惕性,发现可茎突综合征病人,及时做医学影像检查和咽部触诊。  相似文献   
5.
BACKGROUND: In view of the disappointing progress made in the last 20 years in reducing maternal mortality in low-income countries and before going to scale in implementing the new evidence-based strategies, it is crucial to review and assess the progress made in pilot countries where maternal mortality reduction programs focused on emergency obstetric care. OBJECTIVE: To review the process indicators recommended for monitoring emergency obstetric care and their application in field situations, examining the conditions under which they can be used to assess the progress of maternal mortality reduction programs. METHODS: Five of the six UN recommended process indicators were monitored annually for 5 years in selected districts of Morocco, Mozambique, India and Nicaragua. Trends are presented and discussed. RESULTS: With specific variations due to different local situations in the four countries and in spite of variations in quality of data collection, all indicators showed a consistent positive trend, in response to the inputs of the programs. CONCLUSIONS: The UN process indicators for emergency obstetric care should continue to be promoted, but with two important conditions: (1) data collection is carefully checked for quality and coverage; (2) efforts are made to match process and outcome indicators (maternal and perinatal mortality, incidence of complications).  相似文献   
6.
辣蓼颗粒成型工艺的研究   总被引:1,自引:0,他引:1  
目的探讨辣蓼颗粒的成型工艺条件。方法考察不同辅料即乳糖、玉米淀粉和糊精对浸膏粉吸湿性的影响;用正交试验法优选制粒工艺条件及评价颗粒的流动性与吸湿性等。结果3种辅料均可明显降低浸膏粉的吸湿性;最佳制粒工艺条件为浸膏粉与玉米淀粉、乳糖按2:2:1的比例混匀,以75%乙醇为润湿剂制软材,湿粒以70%温度干燥,成品颗粒的流动性好;临界相对湿度为75%。结论混合辅料(玉米淀粉和乳糖)可改善浸膏粉的成型性和颗粒剂的抗湿性;辣蓼颗粒制粒工艺条件的优化为产品的工业生产环境控制提供了科学依据。  相似文献   
7.
在心室晚电位的研究中,我们引入了信号的时间一频率表示法,并根据晚电位的具体特性用Wigner分布法(维格纳分布)把信号表示为在时间及频率空间中的能量分布。由于Wigner分布的优异性质使我们有可能更准确表示出心室晚电位的存在。但当输入信号是两个信号的线性叠加时,Wigner分布的结果会出现一个交叉项,相当于引入干扰。针对此不足,作者介绍改进方案,消除部分交叉项,收到较好的效果,并给出一些仿真及应用实例。  相似文献   
8.
Neutrophils migrating in tissue respond to complex overlapping signals generated by a variety of chemotactic factors (CFs). Previous studies suggested a hierarchy between bacteria-derived CFs and host-derived CFs but could not differentiate neutrophil response to potentially equal host-derived CFs (IL-8 and LTB4). This paper reports neutrophil migration in conflicting gradients of IL-8 and LTB4 using a microfluidic chemotaxis device that can generate stable and well-defined gradients. We quantitatively characterized the movement of cells from time-lapse images. Neutrophils migrate more efficiently toward single IL-8 gradients than single LTB4 gradients as measured by the effective chemotactic index (ECI). In opposing gradients of IL-8 and LTB4, neutrophils show obvious chemotaxis toward a distant gradient, consistent with previous reports. When an opposing gradient of LTB4 is present, neutrophils show less effective chemotaxis toward IL-8 than when they are in a gradient of IL-8 alone. In contrast, the chemotactic response of neutrophils to LTB4 is not reduced in opposing gradients as compared to that in a single LTB4 gradient. These results indicate that the presence of one host-derived CF modifies the response of neutrophils to a second CF suggesting a subtle hierarchy between them.This revised version was published online in May 2005 with corrected author affiliations  相似文献   
9.
Single neuronal activities were recorded in the oral region of the postcentral gyrus in conscious Japanese monkeys. Among 5,756 neurons isolated, receptive fields (RFs) and submodalities were identified in 1,502 neurons in area 3b, 970 in area 1, and 1,461 in area 2. The relative incidence of neurons that had bilateral RFs increased gradually upon moving caudally from area 3b to area 2 (bilateral integration). A total of 276 neurons had bimaxillary RFs covering both the maxillary and mandibular divisions of the trigeminal nerve, such as the upper and lower lips, upper and lower teeth, palate and tongue, or combinations thereof. There was also a tendency for the relative incidence of neurons with bimaxillary RFs to increase across the postcentral gyrus but with an abrupt change in area 2 (bimaxillary integration). A total of 382 neurons had composite RFs covering more than one of five oral structures: lip, cheek mucosa, teeth/gingiva, tongue, and palate. The relative incidence of neurons with composite RFs was significantly higher in area 2 than in areas 3b and 1 (interstructural integration). These results indicate that the convergence of inputs from oral structures proceeds in a hierarchical manner across the postcentral gyrus, but chiefly in area 2 for the bimaxillary and interstructural integrations. The relative incidence of neurons with composite RFs was higher among neurons associated with the teeth/gingiva or palate than among neurons associated with the tongue or lip in all three areas. We interpret this to mean that anatomical or functional differences between oral structures might be reflected in the converging patterns in the oral representation.  相似文献   
10.
目的探索老年患者日间手术全程质量管理模式。方法通过医院病历系统采集2015年-2020年应用老年患者日间手术全程质量管理模式前后患者信息,进行对比分析。结果老年患者应用日间手术全程质量管理模式后,≥65岁老年患者日间手术人数逐年上升,占比从13.52%上升至18.62%,差异有统计学意义(χ2=6.450,P=0.011);日间手术住院时间>5 d的比例从0.72%下降至0.50%,差异有统计学意义(χ2=338.088,P<0.001);不良事件发生率从3.77‰下降至1.56‰,差异有统计学意义(χ2=5.156,P=0.023),其中严重不良事件发生率从2.08‰下降至0.35‰,差异有统计学意义(χ2=7.019,P=0.008)。结论应用日间手术全程质量管理模式能够有效提高老年患者日间手术的安全性,值得借鉴与推广。  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