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   88721篇
  免费   6635篇
  国内免费   2485篇
耳鼻咽喉   208篇
儿科学   1954篇
妇产科学   994篇
基础医学   7975篇
口腔科学   1169篇
临床医学   12485篇
内科学   13232篇
皮肤病学   897篇
神经病学   4160篇
特种医学   3567篇
外国民族医学   4篇
外科学   6251篇
综合类   15579篇
现状与发展   6篇
一般理论   1篇
预防医学   8485篇
眼科学   825篇
药学   9089篇
  86篇
中国医学   9052篇
肿瘤学   1822篇
  2024年   153篇
  2023年   1154篇
  2022年   1659篇
  2021年   3388篇
  2020年   3123篇
  2019年   2620篇
  2018年   2486篇
  2017年   2768篇
  2016年   2901篇
  2015年   2911篇
  2014年   5479篇
  2013年   5954篇
  2012年   5113篇
  2011年   5644篇
  2010年   4341篇
  2009年   3863篇
  2008年   3920篇
  2007年   4118篇
  2006年   3657篇
  2005年   3327篇
  2004年   2964篇
  2003年   2714篇
  2002年   2374篇
  2001年   2265篇
  2000年   1844篇
  1999年   1573篇
  1998年   1441篇
  1997年   1526篇
  1996年   1249篇
  1995年   1213篇
  1994年   1161篇
  1993年   880篇
  1992年   868篇
  1991年   767篇
  1990年   607篇
  1989年   596篇
  1988年   573篇
  1987年   483篇
  1986年   431篇
  1985年   651篇
  1984年   523篇
  1983年   349篇
  1982年   473篇
  1981年   349篇
  1980年   305篇
  1979年   234篇
  1978年   184篇
  1977年   177篇
  1976年   156篇
  1975年   75篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
61.
In the Netherlands, safe and sufficient drinking water is provided to the general population by ten drinking water companies. To guarantee safe drinking water the World Health Organization (WHO) developed a Water Safety Plan (WSP), a Risk Assessment and a Risk Management (RA/RM) framework. The objective of the study was to identify legally required RA approaches, to document application of RA/RM activities at Dutch drinking water companies and to determine to what extent these RA/RM activities as a whole cover all the elements of the WHO WSP approach. This study could be of interest to both managers of large water utilities and decision makers.The assessment was performed by means of a policy review and interviews with two to four staff members involved in RA/RM from all ten Dutch drinking water companies combined with a joint workshop. The drinking water companies are well aware of the potential hazards and risks that can influence the drinking water quality. To guarantee the supply of safe and sufficient drinking water, the Dutch drinking water sector uses six different legally required RA/RM approaches. This study shows that by using the six legally required RA/RM approaches, all WSP steps are covered. WSP entails a generic risk assessment for identifying all hazards and hazardous events from source to tap, whereas the six legally required RA/RM each focus on specific risks at an advanced level. Each risk assessment provides information on specific hazards and hazardous events covering a part of the water supply chain. These legal requirements are complemented with additional RA/RM activities at sector and water company level such as codes of practices and standard operating procedures. The outcomes of all RA/RM approaches combined provide information from source to tap. When using multiple RA/RM approaches, it is crucial to share and combine information derived from the different activities.  相似文献   
62.
目的探究临床用乌司他丁辅助治疗重症感染性休克的治疗效果。方法90例重症感染性休克患者,随机分为观察组与对照组,每组45例。对照组患者采用西医常规治疗,观察组患者在对照组基础上联合乌司他丁治疗。比较两组患者治疗效果、体温情况、感染情况以及治疗前后白细胞计数、白细胞介素-6(IL-6)水平、格拉斯哥昏迷量表(GCS)评分、急性生理功能和慢性健康状况评分系统Ⅱ(APACHEⅡ)评分。结果治疗后,观察组白细胞计数(7.34±1.32)×10^9/L低于对照组的(9.41±1.16)×10^9/L,差异具有统计学意义(P<0.05)。治疗后,观察组高热、感染体征发生率分别为97.78%、86.67%,均高于对照组的82.22%、62.22%,差异具有统计学意义(P<0.05);观察组体温恢复时间、感染消失时间分别为(7.19±1.39)、(3.88±0.89)d,均短于对照组的(9.81±1.88)、(10.76±1.57)d,差异具有统计学意义(P<0.05)。观察组患者血清IL-6为(4.27±0.95)μg/L低于对照组的(9.58±1.07)μg/L,差异具有统计学意义(P<0.05)。观察组患者GCS评分和APACHEⅡ评分较治疗前均有所改善,GCS评分(8.19±1.59)分、APACHEⅡ评分(8.83±0.82)分均优于对照组的(6.81±1.82)、(14.71±3.52)分,差异均具有统计学意义(P<0.05)。观察组患者治疗总有效率95.56%明显高于对照组的77.78%,差异具有统计学意义(χ^2=6.154,P<0.05)。结论乌司他丁具有较好的抗炎效果,与西医治疗相结合可以提高临床疗效,加快重症感染性休克患者退热速度,缩短感染时间,降低白细胞计数及血清IL-6水平,改善GCS评分和APACHEⅡ评分,临床疗效较好。  相似文献   
63.
化学药合成过程中水分残留不利于反应的进行,还影响药物及制剂的稳定性、理化性质、溶出及药理作用等,因此水分几乎是大多数药物合成中的必测项目,通过有效除水严格控制反应体系中水分的含量至关重要。本文综述了水分的存在形式,常见除水剂和脱水剂的种类、作用原理与除水能力,以及在药物合成的应用,为药物合成反应中水分的去除提供参考。  相似文献   
64.
尚前 《中国卫生产业》2020,(8):175-176,179
该文总结该市2017年1月-2018年12月之间,在无偿献血宣传招募方面工作内容。结果显示2018年较2017年献血总量有所提升,其中团体献血所占比例逐渐上升,街头献血所占比例逐渐下降。通过大力宣传无偿献血工作,扩大无偿献血团体招募工作,完善并深化无偿献血各项制度,使得普通群众的无偿献血认知度不断提高。  相似文献   
65.
目的观察肛窦炎应用针刺配合肠炎散保留灌肠治疗的效果。方法选取2017年10月-2018年10月就诊的72例肛窦炎患者,采用随机数字表法分为观察组(n=36)与对照组(n=36)。对照组给予肠炎散保留灌肠治疗,观察组为针刺配合肠炎散保留灌肠治疗,比较2组症状、疗效及安全性。结果观察组症状(放射痛、指诊症状及镜检症状)少于对照组,总有效率高于对照组,差异有统计学意义(P<0.05);2组安全性相比,差异无统计学意义(P>0.05)。结论针对肛窦炎患者,予以针刺配合肠炎散保留灌肠治疗效果确切,可减少临床症状,加快疾病转归,且治疗安全性较好。  相似文献   
66.
67.
Basic biochemical tests are frequently obtained in acutely unwell neonates and children, as well as in some elective situations. Correct interpretation can be invaluable in identifying rare inherited primary metabolic disorders, but secondary causes of hyperammonaemia, elevated blood lactate or blood gas derangement are more common and require appropriate treatment of the underlying cause. This Personal Practice guide provides an overview of these tests and their interpretation.  相似文献   
68.
《Journal of endodontics》2019,45(6):742-749
IntroductionThis study evaluated free water loss–induced residual strain with and without axial compressive loading and assessed the mechanical effect of cyclic loading in fully hydrated and partially dehydrated root dentin.MethodsRoot dentin sections prepared from freshly extracted human premolars were used. Customized 3-dimensional digital image correlation was used to qualitatively and quantitatively analyze the residual strain induced by 2 hours of free water loss in different regions of root dentin. Residual strain in partially dehydrated root dentin during axial compressive loading was also analyzed using 3-dimensional digital image correlation. The effect of cyclic loading on load to fracture in fully hydrated and partially dehydrated dentin and their fractography were analyzed using micro–computed tomographic imaging.ResultsFree water loss resulted in a heterogeneous distribution of residual strain and an overall formation of residual compressive strain with areas of tensile strain localized to the root canal and outer dentin. More residual compressive strain was observed in the apical dentin compared with the cervical dentin (P < .05), and more residual shear strain was observed in outer dentin compared with inner dentin (P < .05). Axial loading resulted in an increase in the load-induced compressive strain in the direction perpendicular to dentinal tubules (P < .05). Fully hydrated roots displayed a higher mean (P < .05) and median (P < .05) number of cycles to fracture with microcracks characteristic of toughness.ConclusionsAfter free water loss, root dentin displayed an increased formation of heterogenous residual strain, which resulted in increased axial compressive load-induced strain and a decreased resistance to fatigue failure. The effect of free water loss in the loss of mechanical integrity of root-filled teeth needs further investigation.  相似文献   
69.
A high resolution depth attenuation product (Kdhires) was developed using MODIS 500 m and 250 m spectral bands. The Kdhires was compared with Wang’s operational Kd for the Chesapeake Bay. Minimal differences were observed between the two methods, with greatest deviation occurring in areas of high turbidity in the tributaries. After tuning the new Kdhires, the mean absolute error and bias between the two algorithms was 0.22 m?1 and 0.026 m?1, indicating good agreement. Higher spatial resolution provides for improved retrievals along the coast and into the narrow sections of the tributaries, coinciding with areas of concern to estuarine health and coastal management applications.  相似文献   
70.
Abstract

Background and aim: Capsule retention is the most common adverse event associated with video capsule endoscopy. The use of double-balloon enteroscopy-assisted capsule endoscope retrieval has been increasingly reported in recent years. However, evidence is limited regarding its success rate, associated factors, and subsequent clinical outcomes.

Methods: A systematic review of relevant studies published before January 2019 was performed. Successful retrieval rate and associated factors, rate of endoscopic balloon dilation, and outcomes after double-balloon enteroscopy were summarized and pooled.

Results: Within 154 associated original articles, 12 including 150 cases of capsule retrieval by double-balloon enteroscopy were included. The estimated pooled successful retrieval rate was 86.5% (95% confidence interval, 75.6–95.1%). Anterograde approach and capsules retained in the jejunum or trapped by malignant strictures were associated with a higher successful retrieval rate than the retrograde approach (62/83 [74.7%] vs. 10/38 [26.3%], p?<?.001) and capsules retained in the ileum (41/41 [100.0%] vs. 43/58 [74.1%], p?<?.001) or trapped by benign strictures (21/21 [100.0%] vs. 65/83 [78.3%], p?=?.043). Endoscopic balloon dilation was performed in 38.8% (95% confidence interval, 22.3–56.3%) of patients with benign strictures. Two perforations (1.3%) were reported as severe adverse events after double-balloon enteroscopy. A significantly lower surgery rate was found among cases with successful video capsule removal compared with unsuccessful cases (7.2% vs. 38.5%, p?=?.002).

Conclusions: Double-balloon enteroscopy is feasible and safe for removing retained video capsule endoscopes, and its use could decrease the need for surgery in patients with benign strictures and facilitate subsequent surgery in patients with malignant strictures.  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