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   41077篇
  免费   2549篇
  国内免费   1678篇
耳鼻咽喉   586篇
儿科学   670篇
妇产科学   2227篇
基础医学   3953篇
口腔科学   212篇
临床医学   5224篇
内科学   1085篇
皮肤病学   180篇
神经病学   6177篇
特种医学   1969篇
外国民族医学   1篇
外科学   8180篇
综合类   6161篇
现状与发展   3篇
预防医学   2301篇
眼科学   39篇
药学   2258篇
  10篇
中国医学   1506篇
肿瘤学   2562篇
  2024年   63篇
  2023年   423篇
  2022年   738篇
  2021年   1372篇
  2020年   1263篇
  2019年   1001篇
  2018年   1188篇
  2017年   1264篇
  2016年   1287篇
  2015年   1332篇
  2014年   2730篇
  2013年   3265篇
  2012年   2526篇
  2011年   2867篇
  2010年   2562篇
  2009年   2247篇
  2008年   2113篇
  2007年   2142篇
  2006年   1902篇
  2005年   1604篇
  2004年   1398篇
  2003年   1245篇
  2002年   1018篇
  2001年   909篇
  2000年   786篇
  1999年   670篇
  1998年   560篇
  1997年   510篇
  1996年   423篇
  1995年   389篇
  1994年   324篇
  1993年   292篇
  1992年   292篇
  1991年   255篇
  1990年   236篇
  1989年   209篇
  1988年   173篇
  1987年   186篇
  1986年   196篇
  1985年   260篇
  1984年   241篇
  1983年   193篇
  1982年   152篇
  1981年   134篇
  1980年   122篇
  1979年   59篇
  1978年   49篇
  1977年   49篇
  1976年   24篇
  1975年   15篇
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
61.
目的 研究转酪氨酸激酶C(tyrosine kinase C,TrkC)基因神经干细胞(neural stem cells,NSCs)移植治疗脊髓损伤的作用。方法 60只SD大鼠随机分成正常对照组(A组)、脊髓半切组(B组)、NSCs移植组(C组)、NSCs移植+神经营养素(NT)-3局部使用(D)组、转TrkC基WNSCs移植组(E组)和转TrkC基因NSCs移植+NT-3局部使用组(F组),每组10只。脊髓损伤后第9天进行细胞移植。各组大鼠在细胞移植后2个月,行体感诱发电位(SEP)和运动诱发电位(MEP)检查以及脊髓运动功能(BBB)评分。结果 细胞移植后2个月SEP和MEP发生潜伏期和峰峰波幅以及右后肢BBB评分的恢复均以下组最佳,与其他各组比较,差异有统计学意义(P< 0.05,0.01)。结论在局部给予的NT-3作用下,转TrkC基因NSCs能较好地促进损伤脊髓功能的恢复。  相似文献   
62.
颈椎病与中医辨证关系的探讨(附100例分析)   总被引:3,自引:0,他引:3  
目的:探讨颈椎病与中医分型的辨证关系。方法:对100例该病的影像表现与中医分型进行系统分析。结果:主要临床表现颈部活动受限,颈、肩、背部疼痛,常伴头痛、头晕、视物模糊、耳鸣等症状。风寒型以软组织所致颈曲改变为主。肝肾亏虚型、痰湿交阻型以骨质增生、椎间隙及椎间孔狭窄为主。结论:X线、CT是本病首选检查方法,能与中医辨证有机结合,对中西医治疗有重要意义。  相似文献   
63.
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   
64.
In normal adult cats we measured the density of staining for the activity of succinate dehydrogenase (SDH staining) in ventral horn cells of different sizes. The measurements were restricted to that part of the lumbar ventral horn (L6-L7) which is known to contain motoneurones of the peroneal nerve. A statistically significant tendency was found for the SDH staining to be denser in smaller than in larger neurones within the size range of a motoneurones (soma diameter greater than 40 microns). These results are consistent with recently published evidence for ventral horn cells of rats and qualitatively similar relationships between size and SDH staining have also been observed among skeletal muscle fibres (confirmed for mixed muscle of cat in present study). In hindlimb muscles, size as well as SDH staining are known to be markedly activity-dependent. We tested whether this is the case for peroneal motoneurones as well by analyzing the effects of chronic nerve stimulation on the properties of neurones within the appropriate region of the ventral horn. Prior to the final acute experiment, these cats had been subjected to a left-side dorsal rhizotomy and hemispinalization. By aid of a portable mini-stimulator, the left-side common peroneal nerve was activated by repetitive pulses during 50% of total time per day (intra-activity rate: 10, 20 or 40 Hz). After 8 weeks of such treatment, cell sizes as well as the densities of SDH staining showed hardly any differences between peroneal ventral horn cells of the experimental and control sides of the spinal cord.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
65.
Between 23 and 70% of occupants involved in frontal impacts sustain cervical spine injuries, many with neurological involvement. It has been hypothesized that cervical spinal cord compression and injury may explain the variable neurological profile described by frontal impact victims. The goals of the present study, using a biofidelic whole cervical spine model with muscle force replication, were to quantify canal pinch diameter (CPD) narrowing during frontal impact and to evaluate the potential for cord compression. The biofidelic model and a sled apparatus were used to simulate frontal impacts at 4, 6, 8, and 10 g horizontal accelerations of the T1 vertebra. The CPD was measured in the intact specimen in the neutral posture (neutral posture CPD), under static sagittal pure moments of 1.5 Nm (pre-impact CPD), during dynamic frontal impact (dynamic impact CPD), and again under static pure moments following each impact (post-impact CPD). Frontal impact caused significant (P<0.05) dynamic CPD narrowing at C0-dens, C2-C3, and C6-C7. The narrowest dynamic CPD was observed at C0-dens during the 10 g impact and was 25.9% narrower than the corresponding neutral posture CPD. Interpretation of the present results indicate that the neurological symptomatology reported by frontal impact victims is most likely not due to cervical spinal cord compression. Cord compression due to residual spinal instability is also not likely.  相似文献   
66.
Idiopathic spinal cord herniation is a rare spinal cord disorder caused by spinal cord prolapse through a adural defect. It is a curable disease, so early detection is of particular importance. We report a 38-year-old woman with Brown-Sequard syndrome which was caused by the thoracic spinal cord herniation. Her weakness was almost completely resolved after surgical management, which emphasizes the importance of early diagnosis and surgical management in this rare disease entity.  相似文献   
67.
目的:探讨经皮激光椎间盘减压术(PLDD)治疗拒绝开放手术的脊髓型颈椎病患者的疗效。方法:2002年~2006年应用PLDD治疗16例拒绝开放手术的脊髓型颈椎病患者,手术前后采用日本骨科学会(JOA)17分法进行评价.计算改善率及优良率,随访观察治疗效果。结果:手术时间平均为15min,术中无明显出血,无血管、神经损伤及感染等并发症发生。术后1、3、6、12个月时JOA评分改善率分别为28.54%、34.82%、41.09%和47.57%.优良率分别为31.3%、37.5%、37.5%和56.0%。随访24个月者11例,改善率为46.56%,优良率为54.4%。结论:PLDD治疗脊髓型颈椎病患者有一定疗效,对拒绝开放手术的脊髓型颈椎病患者是一种可供选择的微创治疗手段。  相似文献   
68.
Objective: Paraplegia remains a serious complication of aortic operations. The production of free radicals during reperfusion after transient ischemia is believed to induce secondary spinal neuronal injury, resulting in paraplegia. The aim of the present study was to clarify the protective effect and method of administration of antioxidants on the neurological and histological outcome in the animal model for reperfusion injury after transient spinal cord ischemia. Methods: New Zealand white rabbits underwent surgical exposure of the abdominal aorta that was clamped for 15 minutes to achieve spinal cord ischemia. Group A animals received two 10 mg/kg doses of 3-methyl-l-phenyl-2-pyrazolin-5-one (MCI-186) at the time of release of the aortic clamp and 30 minutes later. In group B, MCI-186, 5 mg/kg, was given three times, at the time of aorta clamp release, 30 minutes and 12 hours later. In group C (control group), one dose of vehicle was administered. Neurological status was assessed using modified Tarlov’s score until 168 hours after operation. Spinal cord sections were examined microscopically to determine the extent of ischemic neuronal damage. Results: Groups A and B animals had better neurological function than group C (p(0.001). In contrast, group C animals exhibited paraplegia or paraparesis with marked neuronal necrosis. The number of surviving neurons within examined sections of the spinal cord was significantly greater in group B than in group C (p(0.001). Conclusion: In a 15-minute ischemia-reperfusion model using rabbits, systemic repetitious administration of MCI-186, a free radical scavenger, was found to have a protective effect on the spinal cord neurons both neurologically and histologically. We postulate that the drug minimizes the delayed neuronal cell death for reperfusion injury after transient ischemia by reducing the free radical molecules. Moreover, it was thought that we could protect delayed neuronal cell death more effectively by administering MCI-18612 hours later.  相似文献   
69.
Summary The effect of brainstem stimulation was studied on neurones recorded intracellularly in the superficial and deeper laminae of the lumbosacral dorsal horn of the spinal cord in anaesthetised cats. Stimulation in the nucleus locus coeruleus (LC) produced a hyperpolarisation in 4/13 multireceptive neurones and produced a biphasic action consisting of a hyperpolarisation which was followed by a depolarisation in 3/13 neurones. These actions were produced irrespective of whether the multireceptive neurone was located in the superficial or deeper laminae of the dorsal horn. Stimulation failed to produce postsynaptic potentials in the remaining 6/13 multireceptive neurones. The amplitude of hyperpolarisation was increased by the passage of depolarising pulses through the recording microelectrode and decreased by hyperpolarising pulses. Stimulation in other brainstem areas such as, the lateral (FTL), paralemniscal (FTP) and central (FTC) divisions of the tegmental field and the nuclei raphe magnus (NRM) and reticularis magnocellularis (RMc) also hyperpolarised neurones in the dorsal horn. The polarity of hyperpolarisation evoked from some brainstem areas (FTP, FTC, RMc) could be reversed to depolarisation by the passive diffusion of ions from the recording microelectrode containing 3M-KCl. Brainstem (LC, NRM, FTP, FTL) stimulation generated long lasting (700 ms) hyperpolarisation on 4/4 selectively nocireceptive neurones of lamina I. There was, however, no effect on the activity of 5/5 neurones recorded in laminae I/II which in addition to receiving excitatory cutaneous inputs were inhibited by heat stimuli. Stimulation in LC also produced dorsal root potentials (DRPs) and reduced the amplitude of simultaneously recorded excitatory postsynaptic potentials (EPSPs) generated by the activation of primary afferent fibres in 3 multireceptive neurones. It is concluded that inhibition of nociceptive transmission in the spinal cord from LC and other brainstem areas may involve both pre- and postsynaptic mechanisms.  相似文献   
70.
目的探讨我国歼击机飞行员受过载作用对颈椎及周围软组织的影响及其有效预防措施.方法对155名歼击机飞行员和127名地方人员颈椎异常发生率和各类颈椎X线表现进行对比分析.结果歼击机飞行员颈椎异常发生率与地方人员有非常显著差异,各类X线表现:椎体不稳、骨质增生、椎间隙变窄有非常显著差异,项韧带钙化、生理曲度异常有显著差异.结论持续性过载作用可致颈椎退变加剧.  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