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   4385篇
  免费   228篇
  国内免费   100篇
耳鼻咽喉   89篇
儿科学   103篇
妇产科学   90篇
基础医学   267篇
口腔科学   91篇
临床医学   286篇
内科学   258篇
皮肤病学   9篇
神经病学   426篇
特种医学   152篇
外国民族医学   1篇
外科学   1554篇
综合类   459篇
预防医学   119篇
眼科学   19篇
药学   326篇
  3篇
中国医学   56篇
肿瘤学   405篇
  2024年   10篇
  2023年   67篇
  2022年   126篇
  2021年   156篇
  2020年   140篇
  2019年   144篇
  2018年   153篇
  2017年   148篇
  2016年   117篇
  2015年   160篇
  2014年   368篇
  2013年   283篇
  2012年   233篇
  2011年   266篇
  2010年   233篇
  2009年   237篇
  2008年   258篇
  2007年   213篇
  2006年   209篇
  2005年   165篇
  2004年   141篇
  2003年   97篇
  2002年   90篇
  2001年   63篇
  2000年   59篇
  1999年   60篇
  1998年   49篇
  1997年   48篇
  1996年   45篇
  1995年   28篇
  1994年   34篇
  1993年   38篇
  1992年   20篇
  1991年   24篇
  1990年   24篇
  1989年   31篇
  1988年   27篇
  1987年   20篇
  1986年   11篇
  1985年   18篇
  1984年   11篇
  1983年   13篇
  1982年   11篇
  1981年   11篇
  1980年   10篇
  1979年   10篇
  1978年   6篇
  1977年   10篇
  1975年   8篇
  1972年   2篇
排序方式: 共有4713条查询结果,搜索用时 62 毫秒
41.
徐存拴  蔺芳  秦少伟 《解剖学报》2008,39(3):302-309
目的在基因转录水平了解脂类代谢和运输相关基因在大鼠肝再生(LR)中的表达变化和模式。方法用搜集网站资料和查阅相关论文等方法获得参与脂类代谢和运输基因,用大鼠基因组230 2.0芯片检测它们在大鼠再生肝中的表达情况,用比较手术和假手术中基因表达的差异性确定肝再生相关基因。结果初步证实上述基因中193个基因与肝再生相关。肝再生早期[部分肝切除(PH)后0.5~4h]、前期(PH后6~12h)、中期(PH后12~66h)、后期(PH后72~168h)等4个阶段起始表达的基因数为113、20、66和1;基因的总表达次数为250、205、796和293。共上调852次,下调630次,分为27种表达方式。肝再生早期和前期胆汁酸代谢相关基因转录减弱;早期和后期糖皮质激素分解相关基因转录增强;前期和中期磷脂合成相关基因转录增强,磷脂分解相关基因转录减弱;中期脂肪酸、白三烯和鞘糖脂合成相关基因转录增强,甘油三酯和磷脂酰肌醇代谢相关基因转录增强,鞘糖脂分解相关基因转录减弱;中期和后期前列腺素合成和脂肪酸分解相关基因转录增强;几乎在整个肝再生中性激素、糖皮质激素和孕酮合成相关基因转录增强,鞘磷脂代谢相关基因转录增强,脂类运输相关基因转录增强,胆固醇代谢相关基因转录减弱。结论肝再生中脂类代谢和运输变化较大,与肝再生密切相关。  相似文献   
42.
Modern Mind-Brain Reading: Psychophysiology, Physiology, and Cognition   总被引:17,自引:0,他引:17  
This paper reviews the actual and potential benefits of a marriage between cognitive psychology and psychophysiology. Psychophysiological measures, particularly those of the event-related brain potential, can be used as markers for psychological events and physiological events. Thus, they can serve as "windows" on the mind and as "windows" on the brain. These ideas are illustrated in the context of a series of studies utilizing the lateralized readiness potential, a measure of electrical brain activity that is related to preparation for movement. This measure has been used to illuminate presetting processes that prepare the motor system for action, to demonstrate the presence of the transmission of partial information in the cognitive system, and to identify processes responsible for the inhibition of responses. The lateralized readiness potential appears to reflect activity in motor areas of cortex. Thus, this measure, along with other psychophysiological measures, can be used to understand how the functions of the mind are implemented in the brain.  相似文献   
43.
目的:探讨颈内动脉岩内段形态位置变化的规律及其与毗邻结构的关系.方法:对66侧正常成人颅底高分辨率CT连续图像进行分析,测量颞骨气房体积,建立定位颈内动脉岩内段及其毗邻结构的参照系,对其位置和形态进行测量,运用偏相关分析方法求出它们形态位置的变化规律及其影响因素.结果:在男性,颈内动脉垂直段更偏外侧,其水平段长度也大于女性.颞骨气化好,则颈内动脉垂直段更偏后移.颈内动脉垂直段与颈静脉球的位置变化表现为同步.垂直段的内外移位相应地使水平段与中线的夹角发生变化.颈内动脉水平段的方位与蜗轴方向相关,蜗轴偏离中线的角度越小,则颈内动脉水平段偏离中线的角度越大,反之亦然.结论:影响颈内动脉岩内段形态位置变化的因素是复杂和多重的,包括性别因素、颅底发育状态、颞骨气化程度以及毗邻结构发育状态均可能是影响因素.  相似文献   
44.
After partial denervation, the remaining motor units (MUs) of adult fast extensor digitorum longus muscle (EDL) expand their peripheral field. The time course of this event was studied using tension measurement and recordings of electromyographic (EMG) activity. The results show that after section of the L4 spinal nerve, when only 5.3 ± 0.63 of the 40 MUs normally supplying EDL muscle remain, the force of individual motor units starts to increase between the 1st and 2nd week after the operation and continues to do so for a further week. The drastic reduction of the number of motoneurones supplying the fast EDL leads to an increase in activity of the remaining MUs. In the 1st week after partial denervation, there was a sharp increase in the EMG activity of remaining motor units. During the next 12 days, this increase became less marked, but EMG activity remained nevertheless significantly higher than that of the unoperated EDL muscle. Many MUs became tonically active during posture. The EMG activity pattern during locomotion was also altered, so that the burst duration was positively correlated with the step cycle duration. Moreover, shortly after partial denervation, the interlimb coordination was disturbed but returned to its original symmetrical use 1–2 weeks later. Received: 17 September 1996 / Accepted: 3 November 1997  相似文献   
45.
局限性癫痫脑电时间序列的分形维数计算比较   总被引:1,自引:0,他引:1  
为探索应用非线性动力学理论诊断癫痫病的新方法,对局限性癫痫病患者脑电时间序列进行了相关维数(Dc)和波形维数(Dw)的计算比较。观察到,痫性导联脑电的分形维数多低于对侧导联的值;相关维数Dc的相对变化量较波形维数Dw大;而波形维数Dw对痫性棘波敏感;结果提示,脑电时间序列的分形维数有可能成为诊断癫痫的特征参数,值得进一步深入研究。  相似文献   
46.
In an n-back face recognition task where subjects responded to repeated stimuli, ERPs were recorded to upright, inverted, and contrast-reversed faces. The effects of inversion and contrast reversal on face encoding and recognition were investigated using the multivariate spatiotemporal partial least squares (PLS) analysis. The configural manipulations affected early processing (100-200 ms) at posterior sites: Inversion effects were parietal and lateral, whereas contrast-reversal effects were more occipital and medial, suggesting different underlying generators. A later reactivation of face processing areas was unique to inverted faces, likely due to processing difficulties. PLS also indicated that the "old-new" repetition effect was maximal for upright faces and likely involved frontotemporal areas. Marked processing differences between inverted and contrast-reversed faces were seen, but these effects were similar at encoding and recognition.  相似文献   
47.
17 alpha-Alkylated androgens are highly effective in preventing attacks in HAE patients. These drugs, however, seem to be implicated in the development of cholestatic jaundice, peliosis hepatis, and liver tumors. In order to assess the risk-benefit balance of the long-term therapy with androgen derivatives, a follow-up investigation was performed in 13 HAE patients. The results of this study indicate that long-term treatment (15 to 47 mo) with low doses of danazol or stanozolol does not induce significant hepatic damage detectable by laboratory tests or liver biopsy. However, the limited number of patients, although in a rather long period of observation, still suggests a careful control and the use of minimal effective doses.  相似文献   
48.
A clinical and electroencephalographic study of 107 neurologically normal children with partial seizures was undertaken to verify the existence and determine the frequency of epileptic syndromes reported in selected populations. Sixty-three children had simple partial seizures, 39 had complex partial seizures, and 5 children were unclassifiable. The syndrome of benign partial epilepsy of children with rolandic spikes (BPEC, 38 cases) was clearly identified and its uniformly benign final prognosis was confirmed even if some of these children had at times severe or poorly controlled seizures. Among the children with simple partial seizures outside the BPEC (25 cases) and complex partial seizures (39 cases), no homogeneous clinical or electroclinical subgroup could be found. Two children with benign partial epilepsy and myoclonic-astatic seizures ("atypical benign partial epilepsy of childhood") and one child with "benign epilepsy with occipital spike-waves" were identified. 74% of children with epilepsy with complex partial seizures (ECP) had a 1-year seizure-free interval, and many children with epilepsy with simple partial seizures outside the BPEC group (ESP) had no more than two seizures. A benign course is thus not limited to the BPEC but is difficult to predict. Prospective studies are necessary to confirm the existence of well-defined benign syndromes among the idiopathic partial epilepsies of childhood, which appear quite rare outside the BPEC.  相似文献   
49.
The effects of amphetamine on the partial punishment effect (PPE) at one trial per day, were examined. Two groups of animals were trained to run in a straight alley. The continuously reinforced (CRF) group received food reward on every trial. The partially punished (PP) group received food reward on every trial but in addition, received footshocks of a gradually increasing intensity in the goal box on a random 50% of the trials. In the test stage, all animals received both food and footshock on each trial. dl-Amphetamine 1.5 mg/kg was administered in a 2 × 2 design, i.e. drug-no drug in training and drug-no drug in test. The partially punished animals exhibited increased persitence in running to the goal box during test, and this partial punishment effect was unaffected by amphetamine.  相似文献   
50.
目的:探讨喉部分切除术的疗效及修复方法。方法:回顾分析1980年1999年施行喉部分切除术81例的临床资料,其中声门上型喉癌22例、声门型喉癌59例。结果:声门上型喉癌3、5年生存率分别为66.7%、63.2%,声门型喉癌3、5年生存率分别为87.2%、80.5%。拔管率声门上型喉癌为77.2%(17/22),声门型喉癌为93.2%(55/59)。结论:喉部分切除术能保留大部分患者喉的呼吸及发声功能,是根治喉癌的有效术式。  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