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   260606篇
  免费   24658篇
  国内免费   20380篇
耳鼻咽喉   2007篇
儿科学   2294篇
妇产科学   3001篇
基础医学   32476篇
口腔科学   4266篇
临床医学   37585篇
内科学   37481篇
皮肤病学   2389篇
神经病学   14783篇
特种医学   9504篇
外国民族医学   198篇
外科学   24749篇
综合类   43958篇
现状与发展   74篇
一般理论   27篇
预防医学   15483篇
眼科学   8152篇
药学   28065篇
  298篇
中国医学   15561篇
肿瘤学   23293篇
  2024年   790篇
  2023年   3897篇
  2022年   9703篇
  2021年   13947篇
  2020年   10559篇
  2019年   9213篇
  2018年   9650篇
  2017年   8501篇
  2016年   8081篇
  2015年   12152篇
  2014年   14932篇
  2013年   12513篇
  2012年   18718篇
  2011年   21526篇
  2010年   13016篇
  2009年   10054篇
  2008年   13328篇
  2007年   13355篇
  2006年   13585篇
  2005年   13840篇
  2004年   8195篇
  2003年   7606篇
  2002年   6362篇
  2001年   5688篇
  2000年   6425篇
  1999年   7161篇
  1998年   4711篇
  1997年   4725篇
  1996年   3677篇
  1995年   3512篇
  1994年   2896篇
  1993年   1966篇
  1992年   2213篇
  1991年   1842篇
  1990年   1566篇
  1989年   1332篇
  1988年   1133篇
  1987年   952篇
  1986年   737篇
  1985年   608篇
  1984年   348篇
  1983年   214篇
  1982年   115篇
  1981年   126篇
  1980年   82篇
  1979年   90篇
  1965年   1篇
  1962年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
The modification of semiconductor nanostructures with metallic nanocomponents can promote the separation of electron/hole from photoexited semiconductors by forming heterojunctions, thus exhibit enhanced photocatalytic activities and potential applications. In this study, Pt-based NPs, including Pt, PtCu, and PtCuCo are employed as model co-catalysts to comparatively study their capability to enhance the photocatalytic activity of TiO2 nanosheets. It was found that each of Pt, PtCu, and PtCuCo can greatly enhance the photocatalytic activity of TiO2 toward degradation of organic dyes. Using electron spin resonance spectroscopy, we demonstrated that deposition of Pt-based NPs resulted in more production of reactive oxygen species including hydroxyl radicals, superoxide, and singlet oxygen. The enhancing effects of Pt-based NPs on generation of ROS and photocatalytic activity showed same trend: PtCuCo?>?PtCu?>?Pt. The mechanism underlying the enhancement differences in Pt-based NPs may be mainly related to electronic structure change of Pt in alloying with Cu and Co. These results are valuable for designing hybrid nanomaterials with high photocatalytic efficiency for applications in water purification and antibacterial products.  相似文献   
162.
Background: High-quality adverse drug reaction (ADR) reports are essential for conducting drug safety monitoring in pharmacovigilance. The study aim was to assess the current quality of ADR reports in western China, and to identify problems with ADR report quality.

Research design and methods: A sample of 1139 reports received by the Shaanxi ADR Monitoring Center from January 2015 to December 2017 was selected. ADR report quality was evaluated using an ADR report quality evaluation system.

Results: None of the reports were rated as excellent and 1.40% (n = 16) as good. Report quality was better for new and serious reports than for general reports. Medical institutions generated higher quality reports than pharmaceutical manufacturers. Nurses generated higher quality reports than doctors, pharmacists, and other professionals. Reporters of different occupations showed significant differences in the quality of the indicators Reporting time limit, Intervention ADR time, ADR termination time, ADR intervention measures, Original disease, and Cause of medication (P = 0.000).

Conclusions: The ADR data quality was poor in western China, and of lower quality than reported data from previous research in other regions. Improvements in the quality and availability of ADR reports are urgently needed.  相似文献   

163.
目的:研究滋阴清热方治疗对甲状腺功能亢进症阴虚火旺证患者疗效、血浆内皮素-1、炎症因子和免疫功能的影响。方法:将广州市花都区妇幼保健院收治的100例甲状腺功能亢进症阴虚火旺证患者分成观察组和对照组。对照组:给患者使用常规药物治疗;观察组:在对照组的基础上,给予滋阴清热方治疗。干预后,比较两组患者的临床疗效、血浆内皮素-1(Endothelin,ET)、炎症因子[白介素-2(Interleukin-2,IL-2)、白介素-8(Interleukin-8,IL-8)]及肿瘤坏死因子(Tumour Necrosis Factor-α,TNF-α)和免疫功能(CD3^+、CD4^+、CD8^+及CD4^+/CD8^+)。结果:干预前,两组患者IL-2、IL-8及TNF-α无变化,差异无统计学意义(P>0.05);干预后,观察组患者的IL-2比对照组高,且对照组的IL-8及TNF-α比观察组的高,P<0.05,差异有统计学意义;干预前,两组患者的CD3^+、CD4^+、CD8^+及CD4^+/CD8^+与ET无变化;干预后,观察组的CD3^+、CD4^+、CD8+及CD4^+/CD8^+比对照组高,P <0.05,差异有统计学意义,且观察组的ET低于对照组且观察组总有效率明显高于对照组。结论:滋阴清热方治疗降低了血浆内皮素-1,减少炎症的出现,提高免疫功能。  相似文献   
164.
目的应用6σ理论对肿瘤标志物项目的分析性能进行评价,并初步确定各项目的质量目标。 方法收集本实验室2018年1至12月室内质控数据和国家卫生健康委临床检验中心室间质量评价结果,以生物学变异导出的质量规范和国家室间质量评价标准作为允许总误差(TEa)计算6项肿瘤标志物的σ水平,并依据质量目标选择流程图和肿瘤标志物分析性能验证图评价肿瘤标志物的分析性能,进而为肿瘤标志物选择合适的质量目标。 结果应用不同层级的生物学变异导出的质量规范和国家室间质量评价标准,肿瘤标志物项目的σ水平存在显著差异;依据质量目标选择流程图:选择生物学变异导出的"适当的"质量规范作为CA125项目的质量目标,选择生物学变异导出的"最低的"质量规范作为t-PSA、CEA、AFP、CA199和CA153项目的质量目标。 结论6σ能够客观评价肿瘤标志物的分析性能,并为实验室质量目标的选择提供重要的参考价值。  相似文献   
165.
目的:研究右美托咪定在宫颈癌根治术后镇痛及术后快速康复中的临床应用效果。方法:将2015年7月至2018年7月在本院行宫颈癌根治术的86例患者随机分为对照组和观察组各43例。对照组术后镇痛采用舒芬太尼和格拉司琼,观察组术后镇痛加用右美托咪定。采用视觉模拟评分法(VAS)评价患者术后1 h、6 h、12 h、24 h、48 h疼痛情况,采用Ramesay评分法评价患者不同时间点镇静状况,记录并比较两组患者不同时间点收缩压、舒张压、心率及呼吸频率变化,比较两组患者不良反应发生情况。结果:观察组患者术后6 h、12 h、24 h、48 h VAS评分均明显低于对照组(P<0.05),Ramesay评分均明显高于对照组(P<0.05);观察组和对照组患者术后不同时间点呼吸频率比较,差异无统计学意义,但术后6 h、12 h、24 h观察组患者收缩压、心率均明显低于对照组(P<0.05),术后1 h、6 h观察组患者舒张压明显低于对照组(P<0.05);观察组患者恶心呕吐、高血压发生率较对照组明显减低。结论:右美托咪定用于宫颈癌根治术后镇痛,可以提高镇痛镇静效果,稳定患者血流动力学,有助于术后快速康复。  相似文献   
166.
随着医改的不断深入和建立现代医院管理制度的迫切要求,公立医院面临全新的挑战,向管理要效益是实现医院内涵式发展的重要途径。从当前公立医院运营管理的现状入手,通过深入分析存在的问题,为进一步推进公立医院运营管理建设提出思路和建议,对实现公立医院管理转型,提升医院管理水平,实现科学化、精益化管理提供借鉴。  相似文献   
167.
The objective of the present study was to evaluate the clinical, radiological, and functional outcomes of a subscapularis transthoracic surgical approach and a posterolateral surgical approach with debridement, bone graft fusion, and internal fixation for the treatment of upper thoracic tuberculosis.There is currently debate over the best surgical approach for the treatment of upper thoracic tuberculosis. Traditionally, the subscapularis transthoracic approach has been preferred; however, the posterolateral approach has gained popularity in the past few years.A prospective, consecutive cohort of 43 upper thoracic tuberculosis patients with a mean age of 39 years (range: 20–52 years) was followed up for a minimum of 12 months (range: 12–60 months). Patients were randomly divided into 2 groups. Group A (n = 21) was treated by the subscapularis transthoracic approach and group B (n = 22) was treated by the posterolateral approach. All cases were evaluated for clinical, radiological, and functional outcomes. Intraoperative blood loss, operative duration, intraoperative and postoperative complications, hospital stay, the cure rate, fusion time, and the Frankel scale were used for clinical and functional evaluation, whereas the kyphosis angle was used for radiological evaluation.Grafted bones were fused by 10 months in all cases. There was no statistically significant difference between groups before surgery in terms of gender, age, segmental tuberculosis, erythrocyte sedimentation rate (ESR), Frankel scale, or Cobb''s angle (P > 0.05). The average operative duration for Group B was lower than that of Group A. There were no significant differences in intraoperative blood loss, intraoperative and postoperative complications, hospital stay, grafted bone fusion time, or cure rate between groups (P > 0.05). The Cobb''s angle correction rate for group B (68.5%) was significantly better than that of group A (30.9%). The neurological score showed significant postoperative improvement in both groups, with no significant difference between the groups.The subscapularis transthoracic approach and the posterolateral approach with debridement, bone graft fusion, and internal fixation are both sufficient and satisfactory for the surgical treatment of upper thoracic tuberculosis. However, the posterolateral approach is superior to the subscapularis transthoracic approach in terms of surgical trauma, operative time, and kyphosis correction.  相似文献   
168.
The structural properties, elastic anisotropy, electronic structures and work function of D022-type Al3TM (TM = Sc, Ti, V, Y, Zr, Nb, La, Hf, Ta) are studied using the first-principles calculations. The results indicate that the obtained formation enthalpy and cohesive energy of these compounds are in accordance with the other calculated values. It is found that the Al3Zr is the most thermodynamic stable compound. The mechanical property indexes, such as elastic constants, bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, and Vickers hardness are systematically explored. Moreover, the calculated universal anisotropic index, percent anisotropy and shear anisotropic factors of D022-type Al3TM are analyzed carefully. It demonstrates that the shear modulus anisotropy of Al3La is the strongest, while that of Al3Ta is the weakest. In particular, the density of states at Fermi level is not zero, suggesting that these phases have metal properties and electrical conductivity. More importantly, the mechanisms of correlation between hardness and Young’s modulus are further explained by the work function. Finally, the experimental design proves that D022-Al3Ta has an excellent strengthening effect.  相似文献   
169.
170.
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