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   4599篇
  免费   249篇
  国内免费   38篇
耳鼻咽喉   71篇
儿科学   26篇
妇产科学   5篇
基础医学   776篇
口腔科学   46篇
临床医学   328篇
内科学   881篇
皮肤病学   9篇
神经病学   757篇
特种医学   192篇
外国民族医学   1篇
外科学   861篇
综合类   358篇
预防医学   54篇
眼科学   249篇
药学   186篇
  2篇
中国医学   66篇
肿瘤学   18篇
  2023年   113篇
  2022年   165篇
  2021年   238篇
  2020年   191篇
  2019年   179篇
  2018年   152篇
  2017年   164篇
  2016年   124篇
  2015年   123篇
  2014年   249篇
  2013年   229篇
  2012年   178篇
  2011年   221篇
  2010年   177篇
  2009年   190篇
  2008年   201篇
  2007年   167篇
  2006年   157篇
  2005年   156篇
  2004年   145篇
  2003年   108篇
  2002年   76篇
  2001年   87篇
  2000年   93篇
  1999年   100篇
  1998年   70篇
  1997年   83篇
  1996年   51篇
  1995年   53篇
  1994年   57篇
  1993年   59篇
  1992年   60篇
  1991年   39篇
  1990年   35篇
  1989年   36篇
  1988年   41篇
  1987年   43篇
  1986年   27篇
  1985年   29篇
  1984年   25篇
  1983年   21篇
  1982年   36篇
  1981年   22篇
  1980年   21篇
  1979年   18篇
  1978年   13篇
  1977年   9篇
  1976年   23篇
  1974年   5篇
  1973年   8篇
排序方式: 共有4886条查询结果,搜索用时 15 毫秒
21.
The association of craniosynostosis with ectopia lentis is extremely rare. This was recently reported in monozygotic twin sisters, supporting a genetic etiology for this syndromic association. We report on female first cousins once removed who were born with unilateral coronal synostosis. One cousin also had peripheral pulmonic branch stenosis at birth and was later found to have ectopia lentis and severe myopia. The other cousin had an atrial septal defect, mitral valve prolapse, and only mild myopia. Their intelligence is normal. The inheritance is likely autosomal dominant with variable expression and incomplete penetrance and further defines this syndrome to include congenital heart defects. These findings will have important implications for genetic counseling. © 2001 Wiley‐Liss, Inc.  相似文献   
22.
在杏仁内侧核微量注射精氨酸加压素(AVP)和精氨酸加压素单克隆抗体(AVPMc-Ab),观察其对兔内毒素(ET)性发热效应的影响。结果表明,杏仁内侧核微量注射AVP能明显抑制兔ET性发热效应,注射AVPMcAb则能明显提高兔ET性发热效应;而将AVP和AVPMCAb注射到杏仁外侧核则对兔ET性发热效应无明显影响。提示:杏仁内侧核也是AVP抗热作用的一个重要作用部位。  相似文献   
23.
The presence and binding properties of epidermal growth-factor receptors (EGF-Rs) in different cell types purified from the rat medial septal area in culture were investigated. We report that astrocytes, oligodendrocytes and neurons from this area possess EGF-Rs while microglia do not. EGF-binding sites are detectable on astrocytes derived from the medial septum of both embryonic and neonatal rats. Scatchard analysis of the data for astrocytes from the fetal rats show that EGF specifically binds to both high- (Kd = 7.21 × 10−10 M, Bmax = 3602 receptors/cell) and low-affinity (Kd = 3.99 × 10−8 10−8 M, Bmax = 6,265 receptors/cell) receptors on these cells. On the other hand, astrocytes purified from neonatal tissue possess a greater number of high-affinity receptors (Bmax = 10,938 receptors/cell) when compared with the embryonic astroglia. With time in culture, the number of both types of receptors on neonatal astrocytes decreases. Oligodendrocytes also possess high- and low-affinity EGF-Rs with dissociation constants of 3.25 × 10−10 M and 3.85 × 10−8 M, respectively. The number of receptors on oligodendrocytes is significantly lower than those on neonatal astrocytes (Bmax = 1185 and 25,081 receptors/cell for high- and low-affinity binding sites, respectively). Finally, neurons from this area also exhibit two different EGF-R types with dissociation constants similar to those described for astrocytes. As the number of receptors/neuron (Bmax = 136 and 1159 receptors/cell for high- and low-affinity binding sites, respectively) appears to be extremely low, it is possible that EGF specifically binds only to a subpopulation of neurons from this area. These studies demonstrate which cell types in the developing medial sepal area posses EGF-Rs and provide a detailed characterization of these binding sites. These EGF-R-bearing cells may be potential targets for this growth factor or for transforming growth factor α in this brain area.  相似文献   
24.
腓动脉皮支逆行岛状皮瓣的解剖与应用改进   总被引:6,自引:0,他引:6  
目的探讨腓动脉皮支逆行岛状皮瓣的解剖学基础及临床应用效果。方法采用新鲜及防腐尸体下肢共25肢,对腓动脉皮支进行解剖学观测。于2003年9月~2005年6月收治足跖趾关节处软组织缺损患者10例,男8例,女2例。年龄21~55岁。其中背侧6例,跖侧4例,缺损范围10cm×6cm~15cm×10cm。应用带有外踝上11.0±1.7cm腓动脉固定皮支的腓动脉皮支逆行岛状皮瓣修复,皮瓣范围11.0cm×6.5cm~16.0cm×11.0cm。供区6例直接减张缝合,4例行自体游离皮片覆盖。结果解剖学观测外踝上11.0±1.7cm自腓动脉发出一固定皮支,起始点直径1.45±0.12mm,入深筋膜点距腓肠神经营养血管皮瓣轴线15.70±1.20mm。10例患者术后皮瓣均成活,血运良好,无静脉回流障碍;供区愈合良好。术后获随访6~12个月,皮瓣外形良好,质地、色泽与周边相似,足功能恢复良好,两点辨别觉11~18mm。结论腓动脉皮支逆行岛状皮瓣经改进后血运好,逆转距离长,修复范围大,操作简便,为临床修复足中远端软组织缺损提供了一种新方法。  相似文献   
25.
对30侧成人颊脂体的形态,位置和血液供应进行了观测。颊脂体血供为多源性,主要血管蒂为上颌动脉的颊动脉和面动脉的颊支。依据上述血管蒂的解剖学走向和分布,颊脂体转位可修复邻近的颌面部和口腔软组织缺损。  相似文献   
26.
Summary A case of combined use of bilateral medial thigh skin flaps and gracilis musculocutaneous flaps for the reconstruction of a scrotal defect resulting from Fournier's gangrene is presented. The procedure provided a sac-like scrotum, and the donor sites were successfully reconstructed using bilateral gracilis musculocutaneous V-Y advancement flaps.  相似文献   
27.
A9 and A10 units identified as dopaminergic were recorded with extracellular micropipettes. The units were antidromically activated by electrical stimulation at the level of the preoptic area. The absolute refractory periods ranged from 1.2 to 2.5 ms. During the 2–8 ms of the relative refractory period, conduction was slower than normal by up to 1.5 ms. The time constant, C, of the strength-duration curve ranged from 0.4 to 0.6 ms. The current (I)-distance (D) relationship, tested by moving the stimulating electrode past the axon, was approximately parabolic (I = K D exp 2), with the constant of the equation, K, ranging from 900 to 2000 μA/mm exp 2, for 0.5 ms pulses. This relationship allows calculation of the radius of the field of dopamine axon excitation at any current. These high K values show that axons of dopamine cells cannot be activated unless high current densities are derivered, even when electrodes are placed near the axons. These data allow determination of the extent to which dopamine axons can be the directly activated substrates for behaviors, such as self-stimulation and circling, which are evoked by electrical stimulation of the medial forebrain bundle or internal capsule.  相似文献   
28.
目的探讨应用尺神经腕背支营养血管逆行皮瓣修复小指皮肤缺损的临床效果及手术操作要点。方法以尺神经腕背支营养血管远端为蒂,选择小指尺侧分支为皮瓣轴心血管,将皮瓣向小指远端转移,修复小指掌背侧皮肤缺损8例。结果8例全部成活,其中1例因创面止血不彻底,皮瓣受压导致远端部分坏死,经换药后痊愈。结论尺神经腕背支走向较恒定,本组未发现变异。沿皮神经干有纵行的皮神经旁血管网及皮神经干内血管网,此皮瓣血供可靠的,皮瓣切取容易,对供区影响小,是修复小指皮肤缺损的理想方法。  相似文献   
29.
We have investigated the distribution of vasopressin binding sites in the brain of male and female adult mice using a radio-iodinated ligand and film autoradiography. Vasopressin receptors were uncovered in various regions of the brain including the basal nucleus of Meynert, the substantia innominata, the hypothalamic paraventricular nucleus, the substantia nigra pars compacta and the hypoglossal nucleus. A sex-related difference in the expression of vasopressin receptors was seen in the medial preoptic area/anterior hypothalamus corresponding to the rat sexually dimorphic nucleus in the rat and in the hypothalamic mammillary nuclei. In both structures the autoradiographic labeling is more intense in females than in males. These observations confirm that vasopressin binding sites are present in the hypothalamic preoptic area of most species examined so far and that sex-related expression of neuropeptide receptors could trigger sex-related behavioral differences.  相似文献   
30.
Equating the condition after cardiac arrest with that of medial temporal damage, and consequently medial temporal lobe amnesia, is questioned on the basis of results from a patient who was studied neuropsychologically as well as with static and dynamic imaging methods (MRI, PET) 6–9 months after a heart attack. The patient manifested severe and persistent anterograde and retrograde amnesia, as well as further cognitive deteriorations. While MRI only indicated non-specific cortical atrophy, PET revealed a severe bilateral affection of the thalamus and of both medial and lateral temporal cortices as well as occipito-parietal hypometabolism. The neuropsychological status indicates that patients with a diagnosis of cardiac arrest may suffer very severe and persistent cognitive deficits; the imaging analyses show that cardiac arrests may lead to quite severe and widespread brain damage which, however, may not be visible with current magnetic resonance imaging technology, but which is clearly apparent from positron emission tomography. These data suggest that patients with a condition after a heart attack may not be valid models for pure hippocampal—or even medial temporal lobe—pathology, as they may suffer much more widespread brain damage.  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