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   14101篇
  免费   1297篇
  国内免费   249篇
耳鼻咽喉   181篇
儿科学   237篇
妇产科学   68篇
基础医学   1353篇
口腔科学   230篇
临床医学   2225篇
内科学   3132篇
皮肤病学   43篇
神经病学   1452篇
特种医学   243篇
外国民族医学   1篇
外科学   2523篇
综合类   2117篇
预防医学   391篇
眼科学   111篇
药学   854篇
  9篇
中国医学   298篇
肿瘤学   179篇
  2024年   43篇
  2023年   301篇
  2022年   477篇
  2021年   674篇
  2020年   609篇
  2019年   597篇
  2018年   542篇
  2017年   481篇
  2016年   435篇
  2015年   440篇
  2014年   771篇
  2013年   769篇
  2012年   659篇
  2011年   731篇
  2010年   544篇
  2009年   589篇
  2008年   605篇
  2007年   620篇
  2006年   539篇
  2005年   495篇
  2004年   464篇
  2003年   379篇
  2002年   322篇
  2001年   325篇
  2000年   268篇
  1999年   265篇
  1998年   242篇
  1997年   242篇
  1996年   203篇
  1995年   210篇
  1994年   202篇
  1993年   196篇
  1992年   178篇
  1991年   149篇
  1990年   127篇
  1989年   111篇
  1988年   113篇
  1987年   81篇
  1986年   74篇
  1985年   109篇
  1984年   98篇
  1983年   72篇
  1982年   68篇
  1981年   52篇
  1980年   54篇
  1979年   23篇
  1978年   21篇
  1977年   23篇
  1976年   21篇
  1975年   13篇
排序方式: 共有10000条查询结果,搜索用时 328 毫秒
21.
Transforaminal injections are sometimes used for the diagnosis and treatment of painful conditions in the lumbar and to a lesser degree in the cervical spine. The technique is most often used when investigating/treating radiculopathy caused by degenerative disease. But how selective are the nerve root blocks? What possible structures other than the intended nerve root are affected from such injections? This study was undertaken in order to try to answer these questions, as no study focusing on the possible spread from the transforaminal selective nerve root blocks in the cervical spine has been performed earlier. In three groups of patients, each group including three patients, we injected three different volumes (0.6, 1.1 and 1.7 ml) with a transforaminal technique in the cervical spine. In all the injections, a small amount of contrast media was added. The spread of the injections were then investigated using multi-slice computed tomography with reconstructions. The imaging revealed a possible effect on other nerve roots than the intended ones when a larger volume was used for the root blocks. The spread was related to the injected volume as well as to local anatomy (size of foraminal area). In this study, only 0.6-ml injections could be accepted for being selective enough for diagnostic investigations.  相似文献   
22.
Twenty-five women receiving sedation for outpatient hysteroscopic polypectomy were injected with 0.25% bupivacaine 10 mL (paracervical group) and another 25 received the same volume of saline (control group) at the cervical fornix. Both groups were given target-controlled propofol sedation during the procedure. More propofol (mg/min) was needed for adequate anesthesia in the control group compared to the paracervical group (6.5 versus 4.6). In addition, the postoperative pain scores were lower in the paracervical group than in the control group. Hemodynamic changes and postoperative side effects were similar in the two groups. This prospective, randomized, double-blind, placebo-controlled study confirmed the effective use of paracervical blocks. This approach has the effect of reducing the amount of intraoperative propofol and decreasing postoperative pain in outpatient hysteroscopic surgery.  相似文献   
23.
We describe a case of 1:1 atrial flutter in a patient with coronary disease taking propafenone. In atrial flutter, the atrial rate is usually about 300 beciis/min with 2:1 AV conduction and a ventricular rate of 150 beats/min. Class IA antiarrhythmic drugs, especially quinidine and disopyramide, may cause 1:1 AV response because they reduce atrial rate and are vagolytic. However, propafenone is a Class IC agent and has no anticholinergic properties, and the occurrence of 1:1 AV conduction at a rate of about 250 beats/min is an important side, effect that, although uncommon, should be recognized.  相似文献   
24.
The thiadiazinone derivative [+]-EMD 60263 ((+)-5-(1-(α-ethylimino-3,4-dimethoxybenzyl)-1,2,3,4- tetrahydroquinoline-6-yl)-6-methyl-3,6-dihydro-2H-1,3,4 -thiadiazine-2-on) is a Ca2+-sensitizing agent with only minor phosphodiesterase inhibitory activity. Our aim was to characterize the inotropic and electrophysiological effects of [+]-EMD 60263 and its enantiomer [-]-EMD 60264 in several cardiac muscle preparations. The Ca2+-sensitizing activity resided in the [+]-enantiomer only. [+]-EMD 60263 (3 μM) shifted the EC50 of Ca2+ for contractile activation of skinned fibers of pig heart from 2.41 μM to 0.73 μM, whereas [-]-EMD 60264 (30 μM) was ineffective. In Langendorff-perfused guinea pig hearts, [+]-EMD 60263 and [-]-EMD 60264 induced concentration-dependent positive and negative inotropic effects, respectively; both enantiomers reduced spontaneous heart rate but did not influence perfusion pressure. The maximum increase in force of human atrial trabeculae was 35 % of pre-drug control with [+]-EMD 60263 in comparison to 113 % with forskolin. In guinea-pig papillary muscles, [+]-EMD 60263 and [-]-EMD 60264 had opposite inotropic responses, however, both agents similarly prolonged action potential duration. Both enantiomers concentration-dependently blocked the rapidly activating component IKr of the delayed rectifier in guinea-pig myocytes. The block saturated at potentials positive to +30 mV, closely resembling the effects of the antiarrhythmic agent E-4031 which had been originally used to define IKr. It is concluded, that the positive inotropic action of [+]-EMD 60263 can be explained by prevalence of the Ca2+-sensitizing effect. The accompanying prolongation in action potential duration is caused by block of the IKr component of the delayed rectifier. While the inotropic effects are stereoselective, most of the electrophysiological actions are clearly independent of sterical configuration. The combination of Ca2+-sensitizing with class-III antiarrhythmic action may provide an interesting pharmacological profile of potential therapeutic use. Received: 7 January 1997 / Accepted: 25 February 1997  相似文献   
25.
颈丛阻滞常可引起心率增快 ,血压增高 ,被认为是颈动脉窦及迷走神经被阻滞 ,交感神经活性增强所致 [1 ]。我们采用艾司洛尔预注射的方法 ,抑制颈丛阻滞后的心血管副反应 ,取得了良好的效果 ,现介绍如下。1 临床资料和方法1.1 一般资料 选择 ASA I~ 级 ,择期行甲状腺瘤或囊  相似文献   
26.
颈丛阻滞、硬膜外阻滞下甲状腺手术应激反应的比较   总被引:2,自引:0,他引:2  
目的 :比较颈丛阻滞、硬膜外阻滞下甲状腺手术应激反应的大小。方法 :选择ASAⅠ~Ⅱ级 ,女性 ,甲状腺手术患者 30例 ,年龄 2 2~ 5 5岁 ,术前无呼吸、循环和内分泌疾病 ,随机分为颈丛阻滞组 (颈丛组 ) 15例 ,硬膜外阻滞组(硬膜外组 ) 15例 ;颈丛阻滞选用 0 .8%利多卡因和 0 .2 5 %布比卡因混合液 ,以C4一点法行双侧深浅丛阻滞 ;硬膜外阻滞选用 1.3%利多卡因和 0 .15 %丁卡因混合液 ,穿刺点选择C4~ 5或C5~ 6间隙 ,采用侧卧位直入法 ,并向头置管 3cm ;分别测定并记录麻醉前、麻醉后 2 0min、切皮、分上极、切腺体和术毕共六个时点的血糖、血压和心率的变化。结果 :两组病例各时点血糖均逐步上升 ,于分上极、切腺体和术毕血糖值与麻醉前比较有显著性差异 (P <0 .0 1) ;硬膜外组只在分上极时SBP与麻醉前比较有差异外 (P <0 .0 5 ) ,而颈丛组在分上极、切腺体时DBP与麻醉前比较有差异 (P <0 .0 5 ) ,SBP、MAP与麻醉前比较有显著性差异 (P <0 .0 1)。结论 :本研究表明颈丛阻滞、硬膜外阻滞均不能完全抑制甲状腺手术的应激反应 ,在稳定甲状腺手术循环功能方面硬膜外阻滞优于颈丛阻滞  相似文献   
27.
目的总结完全性左束支传导阻滞伴快速心房纤颤并急性左心衰竭的治疗经验,以提高抢救成功率.方法对经抢救治疗的完全性左束支传导阻滞伴快速心房纤颤并急性左心衰竭9例(16次)患者进行治疗方面的回顾分析.结果9例(16次)患者14次抢救成功,成功率87.0%,但复发率较高,预后较差,有5例患者在抢救时或出院后1~2年内猝死.结论该组患者经传统"强心、利尿、扩血管",控制心房纤颤、心室率等治疗是远远不够的.应在未发生肺泡性肺水肿及心源性休克之前,尽早尽快地应用血管扩张剂及联合应用小剂量非洋地黄类正性肌力药物,并维持治疗24~72 h.其中以酚妥拉明加多巴胺和(或)多巴酚丁胺效果可能较佳,血管扩张剂硝酸酯类不及α-受体阻滞剂酚妥拉明疗效明显.  相似文献   
28.
目的 观察臂丛神经阻滞的局麻药液中加入地塞米松和小剂量吗啡用于术后镇痛的效果和副作用。方法 80例患者随机分为A、B、C、D四组。全部用肌间沟法臂丛神经阻滞,A组(n=20)注入0.5%布比卡因、2%利多卡因等量混合液25ml;B组(n=20)注入A组用药加地塞米松10mg(2ml);C组(n=20)注入A组用药加吗啡2mg(0.2ml);D组(n=20)注入A组用药加地塞米松10mg(2ml)、吗啡2mg(0.2ml)。结果 B、C、D组与A组相比起效时间显著缩短、镇痛时间显著延长,差异非常显著(P<0.01);而D组和B、C组相比镇痛时间又明显延长,差异非常显著(P<0.01);C组中有1例(5%)因发生恶心呕吐,其余多组无并发症发生。结论 臂丛神经阻滞的局麻药液中加入地塞米松和小剂量吗啡用于术后镇痛,镇痛时间长,效果可靠,副作用少,操作方便,经济实用。  相似文献   
29.
Physiologic assessment of diseases of the motor unit from the anterior horn cells to the muscles relies on a combination of needle electromyography (EMG) and nerve conduction studies (NCS). Both require a unique combination of knowledge of peripheral nervous system anatomy, physiology, pathophysiology, diseases, techniques, and electricity is necessary. Successful, high‐quality, reproducible EMG depends on the skills of a clinician in patient interaction during the physical insertion and movement of the needle while recording the electrical signals. These must be combined with the skill of analyzing electric signals recorded from muscle by auditory pattern recognition and semiquantitation. 10 , 52 This monograph reviews the techniques of needle EMG and waveform analysis and describes the types of EMG waveforms recorded during needle EMG. © 2009 Wiley Periodicals, Inc. Muscle Nerve 39: 244–270, 2009  相似文献   
30.
目的:通过免疫组化的方法研究无水酒精阻滞大鼠腹腔神经丛后脊髓和延髓孤束核内CFOS和NOS1的表达。材料和方法:对70只Wistar大鼠实施手术,建立实验动物模型。分5组于术后不同时间取得脊髓和延髓样本,并用标准方法对其进行CFOS和NOS1免疫组化染色,观察脊髓和延髓孤束核CFOS和NOS1的表达。结果:无水酒精阻滞后脊髓后角、延髓孤束核神经元细胞内均有CFOS和NOS1表达。结论:无水酒精阻滞腹腔神经丛后,短时间内脊髓后角和延髓孤束核内CFOS和NOS1表达阳性,表明FOS和NOS1与内脏信息在脊髓水平的传导有关。CFOS和NOS1参与了内脏信息在孤束核内的传导。  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