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   8058篇
  免费   405篇
  国内免费   236篇
耳鼻咽喉   2篇
儿科学   265篇
妇产科学   96篇
基础医学   246篇
口腔科学   13篇
临床医学   2698篇
内科学   911篇
皮肤病学   63篇
神经病学   79篇
特种医学   208篇
外国民族医学   1篇
外科学   1854篇
综合类   1500篇
现状与发展   1篇
预防医学   244篇
眼科学   12篇
药学   318篇
  10篇
中国医学   148篇
肿瘤学   30篇
  2024年   7篇
  2023年   126篇
  2022年   141篇
  2021年   289篇
  2020年   258篇
  2019年   282篇
  2018年   295篇
  2017年   279篇
  2016年   228篇
  2015年   317篇
  2014年   557篇
  2013年   612篇
  2012年   435篇
  2011年   533篇
  2010年   455篇
  2009年   486篇
  2008年   382篇
  2007年   399篇
  2006年   424篇
  2005年   322篇
  2004年   276篇
  2003年   209篇
  2002年   152篇
  2001年   148篇
  2000年   136篇
  1999年   108篇
  1998年   93篇
  1997年   115篇
  1996年   62篇
  1995年   92篇
  1994年   77篇
  1993年   45篇
  1992年   28篇
  1991年   25篇
  1990年   33篇
  1989年   27篇
  1988年   18篇
  1987年   22篇
  1986年   20篇
  1985年   60篇
  1984年   43篇
  1983年   24篇
  1982年   13篇
  1981年   15篇
  1980年   15篇
  1979年   2篇
  1978年   7篇
  1977年   4篇
  1975年   2篇
  1973年   1篇
排序方式: 共有8699条查询结果,搜索用时 15 毫秒
61.
中药蝶脉灵注射液在心肺复苏中脑保护作用的实验研究   总被引:1,自引:0,他引:1  
目的 探讨中药蝶脉灵注射在心脏骤停时对脑复苏的作用。方法 用电刺激导致室颤制备家兔心脏骤停模型,在光镜和电镜下观察大剂量肾上腺素治疗时,蝶脉灵注射液对脑组织的影响。结果 蝶脉灵注射液对脑细胞有明显的保护作用。结论 蝶脉灵注射液能明显改善心脏骤停时脑缺血性损害,因而有利于脑复苏。  相似文献   
62.
肝素涂层体外循环管道抗凝血性能的研究   总被引:2,自引:1,他引:2  
目的 评测3种离子键肝素涂层体外循环管道的抗凝血性能和稳定性。方法 用PT和APTT对不同浓度肝素—氯烃基二甲基代苯甲胺(HBC)复合物涂层体外循环管道的凝血性能进行评测,同时测试体外转流对3种肝素涂层管道抗凝血性能的影响。结果 3种肝素涂层方法均能够将肝素分子结合于材料表面并具有抗凝活性,其中HBC复合物和肝素—聚乙烯亚胺复合物处理的体外循环管道经体外转流96h后仍具有较佳的抗凝血活性。结论 离子键肝素涂层因结合物质不同其稳定性也不同;HBC复合物和肝素—聚乙烯亚胺复合物处理的体外循环管道肝素分子结合较牢固,能够满足临床短期使用需要。  相似文献   
63.
Whether blood flow during cardiopulmonary resuscitation (CPR) results from intrathoracic pressure fluctuations or direct cardiac compression remains controversial. We developed a mathematical model that predicts that blood flow due to intrathoracic pressure fluctuations should be insensitive to compression rate over a wide range but dependent on the applied force and compression duration. If direct compression of the heart plays a major role, however, the model predicts that flow should be dependent on compression rate and force, but above a threshold, insensitive to compression duration. These differences in hemodynamics produced by changes in rate and duration form a basis for determining whether blood flow during CPR results from intrathoracic pressure fluctuations or from direct cardiac compression. The model was validated for direct cardiac compression by studying the hemodynamics of cyclic cardiac deformation following thoracotomy in four anesthetized, 21–32-kg dogs. As predicted by the model, there was no change in myocardial or cerebral perfusion pressures when the duration of compression was increased from 15% to 45% of the cycle at a constant rate of 60/min. There was, however, a significant increase in perfusion pressures when rate was increased from 60 to 150/min at a constant duration of 45%. The model was validated for intrathoracic pressure changes by studying the hemodynamics produced by a thoracic vest (vest CPR) in eight dogs. The vest contained a bladder that was inflated and deflated. Vest CPR changed intrathoracic pressure without direct cardiac compression, since sternal displacement was <0.8 cm. As predicted by the model and opposite to direct cardiac compression, there was no change in perfusion pressures when the rate was increased from 60 to 150/min at a constant duration of 45% of the cycle. Manual CPR was then studied in eight dogs. There was no surgical manipulation of the chest. Myocardial and cerebral blood flows were determined with radioactive microspheres and behaved as predicted from the model of intrathoracic pressure, not direct cardiac compression. At nearly constant peak sternal force (378–426 N), flow was significantly increased when the duration of compression was increased from short (13%–19% of the cycle) to long (40%–47%), at a rate of 60/min. Flow was unchanged, however, for an increase in rate from 60 to 150/min at constant compression duration. In addition, myocardial and cerebral flow correlated with their respective perfusion pressures. Thus vital organ perfusion pressures and flow for manual external chest compression are dependent on the duration of compression, but not on rates of compression of 60 and 150/min. These data are of course similar to those produced by vest CPR, where intrathoracic pressure is manipulated without sternal displacement, and to those predicted for movement of blood by intrathoracic pressure changes. These data are, however, opposite to those produced by cardiac deformation and to those predicted for movement blood by direct cardiac compression. We conclude that intrathoracic pressure fluctuations generate blood flow during manual CPR.  相似文献   
64.
Complement activation products are major components of the inflammatory response induced by cardiac surgery and cardiopulmonary bypass which contribute to postoperative organ dysfunction, fluid accumulation, and morbidity. Activation of the complement system occurs during extracorporeal circulation, during reperfusion of ischemic tissue, and after the formation of heparin-protamine complexes. In this study we examine the efficacy of Compstatin, a recently discovered peptide inhibitor of complement, in preventing heparin/protamine-induced complement activation in baboons. The study was performed in baboons because Compstatin binds to baboon C3 and is resistant to proteolytic cleavage in baboon blood (similar to humans); Compstatin inhibits only the activation of primates' complement system. After testing various doses and administration regimens, Compstatin produced complete inhibition at a total dose of 21 mg/kg when given as a combination of bolus injection and infusion. Compstatin completely inhibited in vivo heparin/protamine-induced complement activation without adverse effects on heart rate or systemic arterial, central venous, and pulmonary arterial pressures. This study indicates that Compstatin is a safe and effective complement inhibitor that has the potential to prevent complement activation during and after clinical cardiac surgery. Furthermore, Compstatin can serve as the prototype for designing an orally administrated drug.  相似文献   
65.
All citizens (N = 22066) aged 16 to 65 of a medium-sized Belgiantown were personally invited to CPR training sessions held intheir neighbourhood. 1152 responded by attending a trainingsession. Those who did not so respond were surveyed (randomsample N=600) for reasons of their not coming. The sample fittedwell with census data for gender, age and suburb location butnot for job, because retired persons and women at home wereover represented. 123 persons did not want to answer the questions. 116 personssaid they were already trained in CPR, 276 said they would accepton a future occasion and 82 said they would not. Three personsdid not answer this question. There was no discrimination for job, gender and suburb locationbetween those who did and did not accept a future training opportunity,nor was the existence of a heart patient among relatives. Theolder the person, the less inclined was that person to participatein CPR training (age effect x2 = 17.17, d.f. = 9, P<0.05).The 276 who accepted future training, chose their workplace(221) and/or their social meeting place (club etc.) as the placewhere this future training should be held. We suggest that CPR training is well accepted and that the trainingopportunities should be given at places of work and social gatherings.  相似文献   
66.
Zusammenfassung Das Ziel der vorliegenden Untersuchungen bestand darin, das pharmakokinetische Profil von Adrenalin bei endobronchialer (e.b.) und intravenöser (i.v.) Applikation zu erarbeiten und die gemessenen Adrenalin-Plasmaspiegel mit hämodynamischen Messungen zu korrelieren. Die e.b. Applikation von 100 g/kg Adrenalin erwies sich als ebenso effektiv, wie die i.v.-Gabe von 10 g/kg. Dabei war der Wirkungseintritt der e.b.-Gabe von Adrenalin nur geringfügig um einige Sekunden verzögert. Die Bioverfügbarkeit für e.b. verabreichtes Adrenalin lag zwischen 80 und 85%. Der therapeutische Effekt blieb nach e.b.-Applikation von 100 g/kg Adrenalin wesentlich länger erhalten (ca. 30 min) als nach i.v.-Gabe von 10 g/kg (ca. 3–5 min). Aus den Ergebnissen wird geschlossen, daß die tiefe endobronchiale Instillation von 2–3 mg Adrenalin (verdünnt in 5–10 ml Kochsalzlösung) als alternative Dosierungstechnik bei klinischen Reanimationen betrachtet werden kann.
Pharmacokinetics and -dynamics of epinephrine administered endobronchially
Summary The present animal study was designed to investigate the pharmacokinetic behavior of epinephrine after endobronchial (e.b.) and intravenous (i.v.) administration and its correlation to pharmacodynamic measurements. We found the effectiveness of e.b.-epinephrine (100 g/kg BW) to be in the same magnitude as i.v.-epinephrine (100 g/kg BW) with only a slight delay in the pharmacodynamic onset of a few seconds. The bioavailability of e.b.-administration of epinephrine was in the range of 80–85%. The therapeutic effect of e.b.-epinephrine (100 pg/kg BW) lasted much longer (30 min) when compared to i.v.-epinephrine (10 g/kg BW) where the pharmacodynamic effect was terminated after 3 to 5 min. For the clinical situation of cardiopulmonary resuscitation a dose of 2–3 mg epinephrine in 5–10 ml of physiological saline instilled deeply into the bronchial system should be considered as alternative administration technique with fast onset and good effectiveness.
Herrn Prof. Dr. Dr. h.c. F. Stelzner zum 65. Geburtstag gewidmet  相似文献   
67.
Numerous health conditions affecting the musculoskeletal, cardiopulmonary, and nervous systems can result in physical dysfunction, impaired performance, muscle weakness, and disuse-induced atrophy. Due to its well-documented anabolic potential, creatine monohydrate has been investigated as a supplemental agent to mitigate the loss of muscle mass and function in a variety of acute and chronic conditions. A review of the literature was conducted to assess the current state of knowledge regarding the effects of creatine supplementation on rehabilitation from immobilization and injury, neurodegenerative diseases, cardiopulmonary disease, and other muscular disorders. Several of the findings are encouraging, showcasing creatine’s potential efficacy as a supplemental agent via preservation of muscle mass, strength, and physical function; however, the results are not consistent. For multiple diseases, only a few creatine studies with small sample sizes have been published, making it difficult to draw definitive conclusions. Rationale for discordant findings is further complicated by differences in disease pathologies, intervention protocols, creatine dosing and duration, and patient population. While creatine supplementation demonstrates promise as a therapeutic aid, more research is needed to fill gaps in knowledge within medical rehabilitation.  相似文献   
68.
69.
目的:报告4例体外循环心内直视手术后左室破裂修补成功病例,方法:4例心内直视手术后发生左室自发性破裂,再次体外循环阻断主动脉,两条长涤纶补片距裂口10mm处全层修补后,加用组织生物胶和止血纱布覆盖创面,其中1例加用自身心包补片修补。结果:4例病人均修补止血成功,3例康复出院,1例水后第10天因肾功能衰竭而死亡。结论:左室破裂是心脏手术后的严重的并发症,用长涤纶补片距裂口10mm处修补,外盖自身心包补片加固,并加用组织生物胶,止血纱布粘固是一种有效的修补方法。  相似文献   
70.
Summary The potent antioxidative potential of propofol during cardiopulmonary bypass (CPB) in adults was investigated. The selected 30 patients receiving open heart surgery under CPB were randomly divided into group A and group B. The patients in the group A and group B were given propofol (0. 1 mg. kg−1, min−1 and fentanyl (5 μg. kg−1, min−1) respectively to maintain anesthesia after aorta was cross-clamped. Blood samples were drawn pre-anesthesia, pre-CPB, at 30 min of CPB, at the end of CPB, at 1 h after CPB, at the end of operation, at 12 and 24 h postoperatively. RBC suspension was prepared and erythrocyte glucose-6-phosphate dehydrogenase (G-6-PD) and phosphofructokinase (PFK) activities, total erythrocyte reduced glutathione (GSH) and oxidized GSH (GSSG) were assayed and GSH/GSSG ratio was calculated. In the group A, G-6-PD and PFK activities and GSH/GSSG ratio were almost uneventfully during CPB and postoperatively. In the group B, G-6-PD activity was increased and PFK activity and GSH/GSSG ratio decreased significantly from 30 min of CPB until 12 h postoperatively. It was demonstrated that propofol could obviously attenuate free radical activity during CPB, while fentanyl has no effect on free radical reduction. Propofol could be beneficial as an anesthetic in patients presenting pathologies associated with free radical reactions during CPB. This project was supported partly by a grant from National Natural Sciences Foundation of China (No. 39270660).  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