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   34317篇
  免费   2383篇
  国内免费   2045篇
耳鼻咽喉   1490篇
儿科学   240篇
妇产科学   108篇
基础医学   4820篇
口腔科学   913篇
临床医学   2778篇
内科学   1317篇
皮肤病学   174篇
神经病学   8372篇
特种医学   1150篇
外国民族医学   2篇
外科学   6965篇
综合类   4500篇
预防医学   483篇
眼科学   2413篇
药学   1688篇
  18篇
中国医学   878篇
肿瘤学   436篇
  2024年   50篇
  2023年   447篇
  2022年   690篇
  2021年   1127篇
  2020年   1185篇
  2019年   1037篇
  2018年   998篇
  2017年   1271篇
  2016年   1286篇
  2015年   1249篇
  2014年   2043篇
  2013年   2051篇
  2012年   1654篇
  2011年   1816篇
  2010年   1698篇
  2009年   1513篇
  2008年   1711篇
  2007年   1665篇
  2006年   1531篇
  2005年   1316篇
  2004年   1242篇
  2003年   1126篇
  2002年   990篇
  2001年   884篇
  2000年   729篇
  1999年   685篇
  1998年   672篇
  1997年   616篇
  1996年   502篇
  1995年   452篇
  1994年   402篇
  1993年   369篇
  1992年   391篇
  1991年   330篇
  1990年   334篇
  1989年   270篇
  1988年   227篇
  1987年   238篇
  1986年   233篇
  1985年   314篇
  1984年   266篇
  1983年   179篇
  1982年   204篇
  1981年   180篇
  1980年   165篇
  1979年   114篇
  1978年   76篇
  1977年   69篇
  1976年   54篇
  1975年   30篇
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
61.
目的:探讨降低喉返神经损伤的方法。方法:2005年9月-2007年1月共有375例甲状腺手术患者,对其喉返神经损伤进行分析。结果:375例病人中有5例喉返神经损伤,其中甲状腺腺瘤3例,桥本甲状腺炎1例,甲状腺癌1例,损伤后立即行喉镜检查示声带处于外展位。给予营养神经治疗,15 d-3个月后完全恢复,喉镜检查示声带正常。结论:喉返神经损伤可以预防,关键是术者应熟悉喉返神经的解剖结构和变异,熟悉其与周围组织及血管的关系,要有手术区域的组织结构特别是喉返神经走行的“立体影像”。  相似文献   
62.
We studied the trigeminal and facial motor nuclei of the hagfish by the retrograde HRP method. We distinguished 4 components in a single column of the motor nuclei of the trigeminal nerve and the facial nerve, viz., the pars magnocellularis of the trigeminal motor nucleus (mVm), the anterior part of the pars parvocellularis of the trigeminal motor nucleus (mVp1), the posterior part of the pars parvocellularis of the trigeminal motor nucleus (mVp2) and the facial motor nucleus (mVII). Although in Nissl preparations only the mVm could be distinguished from the rest of the nucleus, the boundaries of the other 3 components were clearly demarcated in HRP preparations. Intramuscular injections into two representative antagonistic jaw muscles revealed that there was no apparent topological organization of the neurons pertaining to the opening and closing muscles in the mVm and mVp1, but both antagonistic muscles were innervated bilaterally. Although the hagfish does possess a cartilaginous jaw, the organization pattern of the motor nuclei of the jaw muscles seems to be the most primitive of all living vertebrates.  相似文献   
63.
64.
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   
65.
66.
用5只猫于左侧颈部食管壁内注入 HRP 溶液,通过 HRP 逆行追踪法研究颈部食管的交感神经支配,结果表明:1.长轴突型交感节前神经元直接分布到食管壁内,其标记细胞位于双侧脊髓的胸1~3节段,以胸2节段最多(占标记细胞总数的66.45%),注射侧占优势。标记细胞主要位于中间带外侧核(约占95.02%),其次为侧索、中介核、前角腹后外侧核。其细胞形态不一,以中小型细胞为主(占标记细胞总数的90.4%)。2.支配颈部食管的交感节后神经元主要位于星状神经节(约占61.99%),余者位于双侧颈前、中和2~5胸交感节内、以小细胞最多。  相似文献   
67.
Neural activity was recorded from the median nerve of a monkey during grasping and lifting, using a chronically implanted cuff electrode. At the onset of lifting, there was an initial dynamic response during which the intensity of the neural signal increased rapidly. This neural response attained its peak value well before the displacement, the load force or the grip force. The time course and peak of the rectified, integrated neurogram were best correlated with the rate of change of grip force. The neural activity declined exponentially to a steady value following the initial peak. During steady holding the mean amplitude of the neurogram was best correlated with the mean grip force. At the end of the holding phase there was a short burst of neural activity as the monkey relaxed the grip force and released the object. During some blocks of trials pulse perturbations were applied to the object. When the monkey did not increase the grip force in advance of the perturbation, the perturbation produced a relatively large displacement of the object and a burst of neural activity whose onset coincided with the onset of displacement. When the monkey anticipated the perturbation by increasing the grip force during the holding period preceding the perturbation, the perturbation produced a relatively small displacement and relatively little increase in neural activity.  相似文献   
68.
To compare nerve regeneration in young adult and aging mice, the right sciatic nerves of 6- and 24-month-old mice were crushed at the sciatic notch. Two weeks later, both groups of mice were perfused with an aldehyde solution, and, after additional fixation, the sciatic nerves were processed so that the transverse sections of each nerve subsequently studied by light and electron microscopy included the entire posterior tibial fascicle 5 mm distal to the crush site. The same level was sectioned in unoperated contralateral nerves; these nerves served as controls. Electron micrographs and the Bioquant Image Analysis System IV were used to measure areas of posterior tibial fascicles and count the number of myelinated axons, the number of unmyelinated axons, and their frequency in Schwann cell units. In aging mice, the total number of regenerating myelinated axons was significantly reduced, but totals of regenerating unmyelinated axons in aging and young adults did not differ significantly. In aging mice, the frequency of Schwann cells that contained a single unmyelinated axon was greater, suggesting that before myelination began, Schwann cell ensheathment of axons also was slowed. After axotomy by a crush injury, the area of the posterior tibial fascicle was less than that in young adults and the distal disintegration of myelin sheath remnants also appeared to be retarded. The results indicate that responses of neurons, axons, and Schwann cells could be important in slowing the regeneration of myelinated fibers found in sciatic nerves from aging mice.  相似文献   
69.
目的 探讨经蝶窦入路穿刺三叉神经节及其分支的可行性,分析两者的毗邻关系及相关限制因素.方法 对110例成年中国人头部薄层CT轴位原始资料进行多平面重组,观察圆孔、卵圆孔、翼腭窝(管)、Meckel腔与蝶窦外侧壁的关系,测量蝶窦外侧壁至诸结构的骨壁厚度.结果 ①圆孔紧靠蝶窦外侧壁的前外下方,骨壁厚度<2 mm者84例(76%);②重组图像可显示翼腭管全程,翼腭窝与蝶窦前下外侧壁之间的骨壁厚度<2 mm者77例(70%);③卵圆孔距离蝶窦外侧壁距离>5 mm 98例(89%);④由蝶窦腔内经颈内动脉管前方入路,斜向后下外方可及Meckel腔,骨壁厚度1~5 mm,颈动脉管为重要骨性标志.结论 经蝶窦内可分别穿刺或开放圆孔、翼腭窝和Meckel腔,而经蝶窦内穿刺卵圆孔基本不可行;经蝶窦入路至三叉神经节及其分支的可及性与蝶窦气腔的位置和扩展程度有关.  相似文献   
70.
老年与青壮年脑挫裂伤组织NGF的表达差异及意义   总被引:1,自引:0,他引:1  
目的 研究衰老对脑挫裂伤组织神经生长因子(NGF)基因表达的影响,进一步探讨老年颅脑损伤病人神经功能缺失程度较重的分子生物学机制.方法 收集重型颅脑损伤开颅手术中的脑挫裂伤组织,应用免疫组化和医学数码图像分析技术,观察老年组(≥60岁)和青壮年组(19~59岁)病人脑损伤后3~9 h脑挫裂伤组织NGF蛋白的表达差异.结果 脑损伤后NGF在老年和青壮年脑挫裂伤组织中的表达均明显增强;老年组脑挫裂伤组织中的NGF蛋白表达显著性低于青壮年组(P<0.05).结论 老年人脑挫裂伤后NGF表达水平下降明显,提示其受损神经元的修复和生存能力降低,这可能是老年颅脑损伤病人恢复不良的重要原因之一.  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