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   3416篇
  免费   119篇
  国内免费   24篇
耳鼻咽喉   356篇
儿科学   25篇
妇产科学   2篇
基础医学   457篇
口腔科学   33篇
临床医学   168篇
内科学   111篇
皮肤病学   2篇
神经病学   1501篇
特种医学   223篇
外科学   143篇
综合类   158篇
预防医学   102篇
眼科学   146篇
药学   86篇
中国医学   11篇
肿瘤学   35篇
  2023年   24篇
  2022年   66篇
  2021年   81篇
  2020年   57篇
  2019年   55篇
  2018年   66篇
  2017年   82篇
  2016年   95篇
  2015年   79篇
  2014年   140篇
  2013年   198篇
  2012年   152篇
  2011年   171篇
  2010年   169篇
  2009年   187篇
  2008年   223篇
  2007年   214篇
  2006年   178篇
  2005年   134篇
  2004年   126篇
  2003年   104篇
  2002年   86篇
  2001年   62篇
  2000年   72篇
  1999年   75篇
  1998年   77篇
  1997年   72篇
  1996年   64篇
  1995年   38篇
  1994年   50篇
  1993年   31篇
  1992年   30篇
  1991年   40篇
  1990年   22篇
  1989年   24篇
  1988年   14篇
  1987年   16篇
  1986年   15篇
  1985年   21篇
  1984年   21篇
  1983年   21篇
  1982年   19篇
  1981年   10篇
  1980年   8篇
  1979年   20篇
  1977年   8篇
  1976年   11篇
  1974年   5篇
  1973年   7篇
  1972年   8篇
排序方式: 共有3559条查询结果,搜索用时 0 毫秒
11.
目的:探讨颞叶癫痫的MRI表现、临床特征及治疗。方法:利用MRI辅以EEG诊断并定位32例颞叶癫痫(TLE),抗癫痫药(AED)正规治疗2年控制不良并外科手术治疗。结果:32例TLE患全部海马萎缩,2例双侧;高信号26例。诊断海马硬化26例。24例手术病理结果证实与MRI结果相符。手术后加药物治疗,效果满意15例,显7例,良好2例。结论:海马萎缩与信号增高是硬化常见MRI表现,有诊断价值。MRI有助于TLE定位诊断。手术加药物是治疗顽固性TLE之重要方法。  相似文献   
12.
Summary Single unit activity of 355 cells was recorded in the auditory thalamus of anesthetized cats before, during, and after the inactivation by cooling of the ipsilateral primary auditory cortex (AI). Most of the units (n = 288) showed similar functional characteristics of firing before and after the cryogenic blockade of AI. The spontaneous firing rate remained unchanged by cooling in 20% of the units and decreased in the majority of them (60%). In some regions, i.e. dorsal division of the medial geniculate body (MGB), lateral part of the posterior group of the thalamus, and auditory sector of the reticular nucleus of the thalamus, the maximum firing rate evoked by white noise bursts was generally affected by cooling in the same direction and to the same extent as the spontaneous activity. Units in the ventral division of MGB showed a characteristic increase of signal-to-noise ratio during cortical cooling. The corticofugal modulation led to the appearance or disappearance of the best frequency of tuning in 51 units and changed it by more than 0.5 octave in 34 units. The bandwidths of different response patterns to pure tones stimulation were used to define a set of functional properties. During cryogenic blockade of AI, two cortically modulated sub-populations of units were usually distinguished that exhibited changes for a given functional property. The complexity and diversity of the effects of cortical inactivation suggest that the corticothalamic projection may be the support for selective operations such as an adaptive filtering of the incoming acoustic signal at the thalamic level adjusted as a function of cortical activity.  相似文献   
13.
14.
Brief interruptions of REM sleep are considered to be part of the REM episode. The maximum allowable duration of such an interruption, which is used to define the end of the REM episode, is currently a matter of debate. Making measurements on individual REM cycles, inter-REM interval analysis was carried out to determine whether the generally adopted 15 minute empirical rule for this maximum needs to be extended to 25 minutes as suggested by several including Kobayashi et al. Our results show that there is no reason to alter the 15 minute rule and that measurements which do not take into account the time-of-night effect may be misleading. The proportion of interrupted REM episodes observed in our population of healthy adults is high. We have therefore also examined in some detail the phenomenology of the temporal evolution of the structure and content of the interrupted REM episodes. Both showed a definite change over the night: the interruptions in the earlier episodes tend to return the system to slow wave sleep while those in the later episodes tend to return it to wake. It is hypothesized that these interruptions reflect a measure of REM sleep pressure and its interaction with both slow wave sleep and wake pressures.  相似文献   
15.
Auditory oddball scalp and limbic P3s were recorded from 18 patients with unilateral temporal lobe epilepsy (TLE) prior to seizure surgery. Limbic P3s were unilaterally absent ipsilateral to the seizure focus and were present in the nonepileptogenic temporal lobe in all 18 cases studied. Scalp P3s, recorded from C3 and C4, on the other hand, were elicited bilaterally and there was no significant difference in amplitude or latency between the epileptogenic and nonepileptogenic sides. These data concur with studies of scalp P3 performed following surgery and suggest that the assessment of the contribution of limbic P3 to scalp P3 may be masked by volume conduction effects and other generators of P3. We conclude that the P3 recorded from central scalp sites, unlike its limbic counterpart, offers little clinical information in the presurgical assessment of patients with TLE.  相似文献   
16.
Summary:  Purpose: Temporal lobe epilepsy (TLE) is probably more difficult to recognize in children than in adults. In fact, ictal symptoms in children are less stereotyped and less obvious, and the neuropathological substrate is more heterogeneous than in adults. The aim of this study is to examine the relationships between etiology, age at onset and electroclinical findings in 77 children with TLE, 32 of whom were surgically treated.
Methods: Electroclinical study including video-EEG recording of seizures in 77 children with TLE. The investigation focused on the first five initial ictal symptoms.
Results: Age at onset was less than 3 years in 39 cases, between 3 and 6 years in 17 cases and older than 6 years in 21 cases. Auras also occurred in younger children but were more common after the age of 6 years. A peculiar initial ictal semiology consisted in staring with arrest, lip cyanosis, and very slight oral automatisms. In some cases, EEG recordings documented seizures starting independently on both temporal lobes. Based on electroclinical and neuroradiological features, we recognized three subgroups: symptomatic TLE due to cortical malformations or nonevolutive tumors, TLE with mesial temporal sclerosis, and cryptogenic TLE.
Conclusions: A correct electroclinical and neuroradiological approach allows in several cases early recognition of TLE even when onset is earlier than the age of 6 years. A correct definition of the localization relies primarily on video-EEG recording of the seizures, possibly repeated during follow up in cases lacking obvious neuroradiological correlation.  相似文献   
17.
OBJECTIVE: The study was designed to investigate the neurocognitive network in the frontal and lateral temporal cortices that is activated by the complex cognitive visuomotor tasks of letter writing. METHODS: Eight epilepsy surgery candidates with implanted intracerebral depth electrodes performed two tasks involving the writing of single letters. The first task consisted of copying letters. In the second task, the patients were requested to write any other letter. The cognitive load of the second task was increased mainly by larger involvement of the executive functions. The task-related ERD/ERS of the alpha, beta and gamma rhythms was studied. RESULTS: The alpha and beta ERD as the activational correlate of writing of single letters was found in the sensorimotor cortex, anterior cingulate, premotor, parietal cortices, SMA and the temporal pole. The alpha and beta ERD linked to the increased cognitive load was present moreover in the dorsolateral and ventrolateral prefrontal cortex, orbitofrontal cortex and surprisingly also the temporal neocortex. Gamma ERS was detected mostly in the left motor cortex. CONCLUSIONS: Particularly the temporal neocortex was activated by the increased cognitive load. SIGNIFICANCE: The lateral temporal cortex together with frontal areas forms a cognitive network processing executive functions.  相似文献   
18.
面神经管病变的多层螺旋CT评价   总被引:1,自引:0,他引:1  
目的:分析面神经管病变CT表现,评价多层螺旋CT的临床价值。方法:回顾性分析面神经管病变患者35例CT资料,男24例,女11例,年龄4~51岁,平均27岁,所有患者均行多层螺旋CT扫描,常规行多平面重建和面神经管曲面重建。结果:面神经管骨折15例,其中鼓室段骨折8例,乳突段骨折5例,迷路段骨折2例;胆脂瘤型中耳炎侵犯面神经管15例;面神经瘤1例,乳突段面神经管前移2例,颞骨骨纤维异常增殖症累及面神经管2例。结论:多层螺旋CT及后处理成像能清晰显示面神经管病变,对临床诊断和治疗有重要价值。  相似文献   
19.
20.
Since it covers the lateral wall of the mastoid air system, the suprameatal triangle is of importance to otologic surgeons during mastoidectomy. Because of this clinical importance, topographic anatomy of the suprameatal spine and depression was studied on Anatolian skulls. In all, 363 male and 231 female skulls were studied. The most prevalent type of suprameatal spine resembled a crest and was found in both sexes on the right (77.6%) and left (80%) sides. The absence of a suprameatal depression was significantly higher in females (right 9.1%; left 8.7%) than in males (right 1.7%; left 2.5%). Suprameatal depressions were mostly shallow in female subjects, but were mostly observed in males to be at a medium depth or deep. Received: 5 January 1998 / Accepted: 19 March 1998  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