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:      
  示例: 沙坡头地区,人工植被区,变化  检索词用空格隔开表示必须包含全部检索词,用“,”隔开表示只需满足任一检索词即可!
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   83602篇
  免费   6444篇
  国内免费   3015篇
耳鼻咽喉   943篇
儿科学   1005篇
妇产科学   787篇
基础医学   10066篇
口腔科学   1408篇
临床医学   8930篇
内科学   11841篇
皮肤病学   1453篇
神经病学   4085篇
特种医学   3955篇
外国民族医学   21篇
外科学   8272篇
综合类   12295篇
现状与发展   28篇
一般理论   7篇
预防医学   5461篇
眼科学   2402篇
药学   8739篇
  85篇
中国医学   4111篇
肿瘤学   7167篇
  2025年   68篇
  2024年   1028篇
  2023年   1249篇
  2022年   2595篇
  2021年   3654篇
  2020年   2737篇
  2019年   2692篇
  2018年   2471篇
  2017年   2356篇
  2016年   2518篇
  2015年   3739篇
  2014年   4615篇
  2013年   4555篇
  2012年   6648篇
  2011年   7044篇
  2010年   4651篇
  2009年   4018篇
  2008年   4991篇
  2007年   4706篇
  2006年   4444篇
  2005年   3921篇
  2004年   2967篇
  2003年   2970篇
  2002年   2473篇
  2001年   1677篇
  2000年   1400篇
  1999年   1252篇
  1998年   791篇
  1997年   702篇
  1996年   599篇
  1995年   543篇
  1994年   520篇
  1993年   345篇
  1992年   374篇
  1991年   343篇
  1990年   288篇
  1989年   262篇
  1988年   173篇
  1987年   188篇
  1986年   141篇
  1985年   96篇
  1984年   55篇
  1983年   39篇
  1982年   38篇
  1981年   27篇
  1980年   28篇
  1979年   17篇
  1975年   7篇
  1973年   10篇
  1972年   6篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.

One-step separation and recovery of sodium, aluminum and iron in high-iron red mud in a high-calcium alkaline hydrothermal system is realized by a high-pressure hydrothermal reduction process. The transformation behavior of the aluminasilica phase in high-iron red mud is mainly investigated. The results show that under the optimized conditions, a temperature of 290℃, a Na2O concentration of 240 g/L, a calcium to silicon ratio of 3.5, and a liquid–solid ratio of 5, the Na2O content in the transition slag is reduced to 0.12%, the dealkalization rate can reach 98%, and the alumina dissolution rate is 73%. When the starch-free reductant is added, the transition slag mainly consists of hematite and hydroandradite, and when the starch reductant is added (the addition amount is 1/4 that of ω(Fe2O3) in the red mud), all Fe2O3 in the transition slag is completely reduced to Fe3O4, and the main phases are magnetite and hydrogrossular.

  相似文献   
42.
微波体模   总被引:9,自引:1,他引:9  
用水、盐,聚氯乙烯粉和羧甲基纤维钠四种材料配制成一种适用的微波体模(模拟肌肉组织)。该体模的复介电系数在300~2500MHz范围内与实际人体肌肉组织的误差≤5%。这种体模的优点是材料立足国内,价廉,室温下配制,使用方便。本文也给出这种体模的温度特性,稳定性和热学特性,供电磁场生物效应和微波热疗等研究使用。  相似文献   
43.
44.
HNE1细胞株光动力学治疗前后形态学的动态变化   总被引:8,自引:2,他引:6  
目的 探讨体外光动力学治疗(PDT)引起鼻咽癌(NPC)细胞死亡的作用机制。方法对鼻咽癌细胞株HNE1体外光动力学治疗前后形态学变化进行动态观察。结果 对照组HNE1细胞培养3h,6h,12h,24h和48h后细胞形态与正常培养组HNE1细包开始变形皱缩,细胞界限模糊,细胞透光度和立体感较差,治疗24~48h后细胞发生凋亡。结论 体外光动力学治疗对HNE1具有明显的杀伤效应并HNE1细胞凋亡。PD  相似文献   
45.
本文用微吸管吸吮技术检测人疲劳运动前后中性粒细胞表面进入微吸管内的距离D(t)有明显差异。提示疲劳运动会降低人中性粒细胞的变形能力,影响其与变形有关的细胞吞噬功能。  相似文献   
46.
探讨中药肛滴在治疗消化道恶性肿瘤中的应用。通过对6例典型病例的回顾分析,观察中药肛滴在缓解癌性粘连性肠梗阻、缓解消化道恶性肿瘤患者症状、提高晚期消化道恶性肿瘤患者生存质量的作用。应用中医理论“通则不痛”之说,对消化道恶性肿瘤患者进行中药肛滴治疗.认为有较好的临床效果。  相似文献   
47.
This article examines 993 violent incidents involving faculty, students, and staff that occurred at a highly ranked teaching and research university and its affiliated medical center. Violent incidents were included in the sample if they involved faculty, students, or staff, regardless of their specific location or context (i.e., whether they occurred on campus and/or off-campus and whether they occurred within the context of work or some other activity). The theoretical goal of the project was to compare work-related incidents with non-work-related incidents of interpersonal violence occurring in a single, multifunctioning, and professionally hierarchical organization. Data were collected over a 7-year period from three police departments (city, county, and university), university records, and criminal history records obtained from the state police. The coding protocol was developed to capture crime-scene information pertinent to each of the incidents. This included information about the victim, the perpetrator, the relationship between the victim and perpetrator, and the violent incident. The data were examined using nonparametric statistics and logistic regression to model predictive differences between the workplace and non-workplace incidents. The results suggest that the workplace incidents of violence differ from the non-workplace incidents according to their time, victim age, degree of victim injury, and whether the workplace is a medical location. The authors conclude that these differences are better explained by the movement of people in and out of the workplace who bring societal violence with them, rather than by a category or type of workplace violence.  相似文献   
48.
目的:前瞻性研究异氰醚分娩镇痛对母体血液动力学的影响。方法:应用国产无创性血液动力学测试仪,对分娩活跃期异氟醚分娩镇痛和对照组产妇共30例的血液动力学状况进行检测。结果:;实验前后,各组母体血液动力学参数;心率(HR),每搏量(SV),每搏指数(SI),心输出量(CO),心脏指数(CI),左室有效泵力(VPE),平均动脉压(MAP)和总外周阻力(TPR)均无显著差异;两组间无显著差异。  相似文献   
49.
OBJECTIVES: To clarify the clinical significance of increased signal intensities on T1 weighted magnetic resonance imaging (MRI) we performed a large-scale epidemiological study on asymptomatic manganese (Mn)-exposed workers with its focus on MRI. METHODS: We randomly selected 121 male workers out of a total of 750 workers including Mn-exposed, non-exposed manual, and non-exposed clerical workers in the factories. We studied environmental and biological monitoring, neurological examination, and MRI. RESULTS: The proportion of workers with increased signal intensities among the exposed, the non-exposed manual workers, and the non-exposed clerical workers was 46.1%, 18.8%, and 0%, respectively. Especially, 73.5% of the welders showed increased signal intensities. In no subject, were clinical signs of manganism observed. The pallidal index correlated with blood Mn concentration. CONCLUSION: Increase in signal intensities on the T1-weighted image reflect recent exposure to Mn, but not necessarily manganism. At which increase of signal intensity, the progression of manganism from Mn exposure occurs, remains to be solved.  相似文献   
50.
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