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   109768篇
  免费   9424篇
  国内免费   6689篇
耳鼻咽喉   1188篇
儿科学   1577篇
妇产科学   786篇
基础医学   10346篇
口腔科学   1892篇
临床医学   11954篇
内科学   15981篇
皮肤病学   1337篇
神经病学   5394篇
特种医学   4672篇
外国民族医学   25篇
外科学   12817篇
综合类   21069篇
现状与发展   27篇
一般理论   10篇
预防医学   9281篇
眼科学   1977篇
药学   11057篇
  109篇
中国医学   6231篇
肿瘤学   8151篇
  2024年   316篇
  2023年   1143篇
  2022年   3032篇
  2021年   4398篇
  2020年   3302篇
  2019年   2714篇
  2018年   2904篇
  2017年   3096篇
  2016年   3083篇
  2015年   4728篇
  2014年   6049篇
  2013年   6324篇
  2012年   9426篇
  2011年   10092篇
  2010年   7919篇
  2009年   6747篇
  2008年   7748篇
  2007年   7727篇
  2006年   6914篇
  2005年   6234篇
  2004年   4633篇
  2003年   4372篇
  2002年   3724篇
  2001年   2267篇
  2000年   1740篇
  1999年   1113篇
  1998年   722篇
  1997年   733篇
  1996年   486篇
  1995年   440篇
  1994年   371篇
  1993年   236篇
  1992年   202篇
  1991年   171篇
  1990年   123篇
  1989年   103篇
  1988年   81篇
  1987年   69篇
  1986年   73篇
  1985年   40篇
  1984年   46篇
  1983年   26篇
  1982年   26篇
  1981年   19篇
  1980年   21篇
  1978年   19篇
  1975年   16篇
  1974年   12篇
  1973年   16篇
  1972年   18篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
By a double-labeling method combining the retrograde tracing of horseradish peroxidase and the immunocytochemical technique, serotonin-like immunoreactive neurons in the midbrain periaqueductal gray (PAG) and nucleus raphe dorsalis (DR) of the rat were observed to send projection fibers to the nucleus parafascicularis of the thalamus bilaterally with an ipsilateral dominance. These serotonin-containing projecting neurons were observed mainly at the middle-caudal levels of the ventrolateral subdivision of the PAG and less at the middle-rostral levels of the DR.  相似文献   
102.
目的 采用HPCE法拆分伯胺类药物对映异构体。方法 缓冲液 2 0mmol/LTris 0 .1%H3 PO4(v/v)(pH 2 .0 6 ) +18 冠 6 四甲酸 (18C6H4) ;检测波长 2 10nm。结果  8种伯胺类药物得以拆分。结论 缓冲液中添加手性冠醚的HPCE法能较好地拆分伯胺类药物。  相似文献   
103.
The purpose of this study was to determine the relationship between segmental hyperintensity of the liver on T1-weighted images and segmental cholestasis in patients with obstructive jaundice. T1-weighted and T2-weighted MR images were obtained of 73 patients with obstructive jaundice caused by various diseases. Fat-suppressed T1-weighted images were also obtained of 10 patients. Eleven patients with segmental intra-hepatic bile duct dilatation (cholestasis) showed segmental hyperintensity on T1-weighted images and/or fat-suppressed T1-weighted images and no signal intensity difference on T2-weighted images. Sixty-two patients with widespread intrahepatic bile duct dilatation showed no intensity difference on T1-weighted and T2-weighted images (P < .01). Segmental hyperintensity on T1-weighted images was correlated with intrahepatic cholestasis.  相似文献   
104.
Abstract: Studies on the circadian rhythm of urine excretion in healthy men have demonstrated that the maximal urine flow occurs in the early afternoon and the minimal around midnight. In this study, an abnormality in the variation of urine volume was found in parkinsonian patients. Urine samples were collected during daytime (9:00–21:00) and nighttime (21:00–9:00). Fifteen healthy control subjects were examined and found to excrete 60% during the daytime and 40% during the nighttime of the total urine volume. Sixteen parkinsonian patients excreted 43% during the daytime and 57% during the nighttime. In contrast to the control subjects, the parkinsonian patients excreted a smaller volume of their urine during the daytime than during the nighttime. This finding might be related to the degeneration of dopaminergic and/or nondopaminergic neurons in the brain which control urinary excretion.  相似文献   
105.
单孔钻颅引流术治疗慢性硬膜下血肿80例临床分析   总被引:7,自引:0,他引:7  
慢性硬膜下血肿(chronic subdural hematoma,CSDH)为受伤3W后出现硬膜下的血肿,是中老年患者轻微颅脑损伤后最为常见的颅内病变。约占颅内血肿的10%,起病隐匿,且临床表现无特征。虽然CSDH的治疗方法多种多样,但单孔钻颅闭式引流方法简单,操作容易,已成为神经外科医师普遍采用的方法。我们近3年来采用单孔钻颅闭式引流术治疗慢性硬膜下血肿80例,效果满意,现报告如下。  相似文献   
106.
目的探讨重型颅脑损伤患者应用洛赛克对应激性溃疡进行防治与胃肠道感染几率增加之间的关系及治疗对策。方法回顾近3年来我院收治的重型颅脑损伤并存活30 d以上病人176例,测定不同时间胃液pH值并分析防治应激性溃疡与发生胃肠道感染的相关性以及相应对策。结果在126例持续应用洛赛克的患者中,持续应用>7 d的患者胃肠道感染发生率明显高于持续应用≤7 d的病人。其余50例间隔应用洛赛克患者与126例持续应用洛赛克患者相比,应激性溃疡发生率无明显差别,但间隔应用洛赛克患者胃肠道感染发生率较持续应用洛赛克>7 d的患者明显下降。结论重型颅脑损伤患者应激性溃疡防治>7 d者,由于胃酸分泌严重抑制,增加胃肠道感染发生率。间隔性应用洛赛克治疗在抑制胃酸分泌,减少应激性溃疡发生的同时,可明显减少胃肠道感染的发生。  相似文献   
107.
OBJECTIVE: To study the effect of the cervical plexus and the accessory nerve to the function of the trapezius muscle. STUDY DESIGN AND SETTING: Eighteen adult male Sprague-Dawley rats were randomly divided into three groups. The neurotomies were performed in the left sides and the right sides served as within-subject controls. In group A, the accessory nerve was transected. The C2-5 were transected in group B, and both of the accessory nerve and C2-5 were cut in group C. The electrophysiologic, myophysiologic, and histologic changes of the muscles were measured. RESULTS: There were significant differences (P < 0.05) between the three groups in the recovery rates of the transverse area of the muscles. The CMAP recorded from the experimental sides in group B were similar to the control sides. The values of the maximum tension of the tetanus contraction between the two sides showed no differences either (P > 0.05). CONCLUSION: The accessory nerve supplies the most important motor input to the trapezius. Motor innervations of the cervical plexus are not very significant.  相似文献   
108.
Objective: To make an epidemiological analysis of the effect of environment on extremely severe road traffic crashes (RTCs). Methods: Epidemiologic data of extremely severe RTCs associated with environmental factors, including weather, topography, road conditions and other traffic conditions in Mainland China during 2000-2001, were collected and analyzed. Results: ( 1 ) During 2000-2001, there were 3 365 extremely severe RTCs with 13 666 deaths, 12 204 injuries and a direct economical loss of 136 million RMB. ( 2 ) Most extremely severe RTCs occurred in fine weather days and in the daytime. The high occurrence sites were plain areas, horizontal and straight roads, Grade B and C roads, ordinary road segment, and asphalt, smooth and mixed roads. (3) Compared with other RTCs, extremely severe RTCs were more likely to happen under following conditions: on cloudy, snowing, misty and blustering days; in hill and mountainous areas; on crooked and sloping roads; on freeway, Grade A, B, and C roads; mixed roads; ordinary, bridge, narrow and transitional roads; sand and dirt-roads; without traffic control measures; night without lighting. (4) Extremely severe RTCs of mountainous area or crooked and sloping roads were most severe in terms of deaths and injures per crash. Conclusions: Extremely severe RTCs are closely related with environmental factors. Rational road programming, enhancing road establishment and improving road conditions are probably effective measures to reduce the road traffic injuries.  相似文献   
109.
目的:探讨铸造夹板式Herbst矫治器和Twin-bolck矫治器矫治Angle Ⅱ2类错的机制和效果。方法:随机选取30例骨龄为FG-G期恒牙列Angle Ⅱ2类错患者,随机分为治疗组(Herbst矫治器组)和对照组(Twin-block矫治器组),其中治疗组15例,采用铸造夹板式Herbst矫治器矫治:对照组15例,采用Twin-blokc矫治器治疗。治疗组和对照组的所有患者均在治疗前、后拍摄头颅定位侧位片,进行矫治前后、颌、面矢状向和垂直向上的头影测量分析,并做统计学处理。结果:两组患者均达到了磨牙中性关系,前牙达到正常的覆盖、覆关系,但是治疗组的疗程明显的短于对照组。结论:Herbst矫治器和Twin-block矫治器均能有效地矫治Angle Ⅱ2类错;但前者在刺激下颌骨生长、促进下颌骨前移等骨性变化以及在患者面型的改善方面明显的优于后者。  相似文献   
110.
目的探讨应用小剂量抗CD3单克隆抗体(OKT3)治疗肾移植术后早期急性排斥反应的效果和安全性.方法将33例发生早期急性排斥反应的肾移植病人分为两组,A组16例(OKT3 5 mg/d);B组17例(OKT3 2.5mg/d).观察排斥反应逆转情况及感染的发生率.结果A组13例(81.25%)急性排斥反应逆转,移植肾功能恢复正常;1例移植肾自发性破裂行移植肾摘除术,2例移植肾失功恢复血液透析.B组15例(88.24%)急性排斥反应逆转,移植肾功能恢复正常;1例移植肾自发性破裂行移植肾摘除术,1例移植肾失功恢复血液透析.两组排斥反应逆转率无显著性差异(P>0.05).A组合并感染43.75%,B组5.88%;两组比较有显著性差异(P<0.05).结论小剂量OKT3治疗肾移植术后早期急性排斥反应的效果良好,并发症少,且费用较低.  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