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   48141篇
  免费   2958篇
  国内免费   2088篇
耳鼻咽喉   173篇
儿科学   731篇
妇产科学   239篇
基础医学   5831篇
口腔科学   135篇
临床医学   5506篇
内科学   2597篇
皮肤病学   39篇
神经病学   16413篇
特种医学   1864篇
外国民族医学   1篇
外科学   2054篇
综合类   8265篇
现状与发展   1篇
预防医学   1183篇
眼科学   372篇
药学   4613篇
  54篇
中国医学   2932篇
肿瘤学   184篇
  2024年   40篇
  2023年   380篇
  2022年   615篇
  2021年   1247篇
  2020年   1326篇
  2019年   1100篇
  2018年   1084篇
  2017年   1395篇
  2016年   1474篇
  2015年   1541篇
  2014年   2622篇
  2013年   2718篇
  2012年   2735篇
  2011年   2944篇
  2010年   2533篇
  2009年   2422篇
  2008年   2490篇
  2007年   2497篇
  2006年   2416篇
  2005年   2146篇
  2004年   1820篇
  2003年   1751篇
  2002年   1462篇
  2001年   1246篇
  2000年   1131篇
  1999年   999篇
  1998年   763篇
  1997年   742篇
  1996年   577篇
  1995年   571篇
  1994年   577篇
  1993年   484篇
  1992年   442篇
  1991年   474篇
  1990年   392篇
  1989年   366篇
  1988年   351篇
  1987年   319篇
  1986年   365篇
  1985年   507篇
  1984年   389篇
  1983年   314篇
  1982年   301篇
  1981年   302篇
  1980年   227篇
  1979年   156篇
  1978年   100篇
  1977年   86篇
  1976年   66篇
  1974年   38篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
51.
目的观察清热化瘀方联合康复训练对脑中风恢复期患者神经功能改善的影响,为临床提供疗效依据。方法选取2019年6月—2019年10月收治的脑中风恢复期患者,采用随机数字表法分为2组,对照组采用常规内科治疗及康复训练,试验组在对照组治疗方案的基础上加用清热化瘀方颗粒,记录并分析2组患者治疗后的临床疗效。结果试验组患者的总有效率高于对照组,试验组治疗后神经功能缺损评分、肢体感觉及运动功能评分、肢体平衡能力评分、生活能力评分均明显优于对照组(P<0.05)。结论清热化瘀方联合康复训练可明显改善脑中风恢复期患者的症状,减轻神经功能缺损程度,提高感觉及运动功能,提高生活能力。  相似文献   
52.
目的探讨芪蛭活血通络饮治疗老年急性脑梗死气虚血瘀证患者临床疗效,观察其对患者炎性指标、纤维化指标、神经功能恢复的影响。方法采用随机数字表法将94例患者分为观察组和对照组各47例。对照组采用西医常规治疗,观察组在对照组基础上予芪蛭活血通络饮,每日1剂,每次150 mL,每日2次,口服(吞咽困难者胃管给药),2组均连续治疗2周。观察2组治疗前后血液流变学指标、转化生长因子-β1(TGF-β1)、同型半胱氨酸(Hcy)、超敏C反应蛋白(hs-CPR)、血管内皮生长因子(VEGF)水平,及神经功能(NIHSS)评分、日常生活能力(ADL)评分,比较2组临床疗效及不良反应。结果与本组治疗前比较,2组治疗后全血高切黏度、全血低切黏度、纤维蛋白原、hs-CPR、Hcy水平明显下降,TGF-β1、VEGF水平明显升高(P<0.05);2组治疗后比较,观察组上述实验室指标改善明显优于对照组(P<0.05)。与本组治疗前比较,2组治疗后NIHSS评分明显降低,ADL评分明显升高(P<0.05);2组治疗后比较,观察组NIHSS评分低于对照组,ADL评分高于对照组(P<0.05)。观察组总有效率为93.62%(44/47),对照组为74.47%(35/47),2组比较差异有统计学意义(P<0.05)。观察组不良反应率为14.89%(7/47),对照组为19.15%(9/47),2组比较差异无统计学意义(P>0.05)。结论芪蛭活血通络饮联合西医常规疗法治疗老年急性脑梗死气虚血瘀证疗效满意,可有效减轻患者炎症反应,改善机体高凝状态,促进神经功能修复。  相似文献   
53.
54.
《Brain stimulation》2020,13(4):943-952
BackgroundIntermittent theta-burst stimulation (iTBS), a novel repetitive transcranial magnetic stimulation (rTMS) technique, appears to have antidepressant effects when applied over left dorsolateral prefrontal cortex (DLPFC). However, its underlying neurobiological mechanisms are unclear. Proton magnetic resonance spectroscopy (1H-MRS) provides in vivo measurements of cerebral metabolites altered in major depressive disorder (MDD) like N-acetyl-aspartate (NAA) and choline-containing compounds (Cho). We used MRS to analyse effects of iTBS on the associations between the shifts in the NAA and Cho levels during therapy and MDD improvement.MethodsIn-patients with unipolar MDD (N = 57), in addition to treatment as usual, were randomized to receive 20 iTBS or sham stimulations applied over left DLPFC over four weeks. Single-voxel 1H-MRS of the anterior cingulate cortex (ACC) was performed at baseline and follow-up. Increments of concentrations, as well as MDD improvement, were defined as endpoints. We tested a moderated mediation model of effects using the PROCESS macro (an observed variable ordinary least squares and logistic regression path analysis modeling tool) for SPSS.ResultsImprovement of depressive symptoms was significantly associated with decrease of Cho/NAA ratio, mediated by NAA. iTBS had a significant moderating effect enhancing the relationship between NAA change and depression improvement.ConclusionsOur findings suggest a potential neurochemical pathway and mechanisms of antidepressant action of iTBS, which may moderate the improvement of metabolic markers of neuronal viability. iTBS might increase neuroplasticity, thus facilitating normalization of neuronal circuit function.  相似文献   
55.
BackgroundCarotid artery dissection (CAD) is a significant cause of ischemic stroke. Early recognition and treatment of CAD is important to prevent accompanying cerebral ischemia. This case report presents an atypical clinical presentation of CAD and emphasizes the diagnostic challenge for emergency physicians.Case ReportA 54-year-old woman presented to the emergency department with a bilateral headache of 4 days’ duration, hypesthesia of the left fifth cranial nerve, dysgeusia, and partial Horner syndrome on the left side. Magnetic resonance angiography showed a left-sided CAD without any signs of cerebral ischemic events. Antiplatelet therapy with clopidogrel was started, and the patient did not show any deterioration in the weeks thereafter.Why Should an Emergency Physician be Aware of This?CAD can present with different combinations of cranial nerve palsies and should be in the differential diagnosis of dysgeusia and hypesthesia of the trigeminal nerve. Early recognition of CAD can be challenging in patients with rare cranial nerve involvement, but early treatment is crucial to prevent cerebral ischemic events.  相似文献   
56.
57.
IntroductionNoradrenergic denervation is thought to aggravate motor dysfunction in Parkinson's disease (PD). In a previous PET study with the norepinephrine transporter (NART) ligand 11C-MeNER, we detected reduced NART binding in primary sensorimotor cortex (M1S1) of PD patients. Idiopathic rapid-eye-movement sleep behaviour disorder (iRBD) is a phenotype of prodromal PD. Using 11C-MeNER PET, we investigated whether iRBD patients showed similar NART binding reductions in M1S1 cortex as PD patients. Additionally, we investigated whether 11C-MeNER binding and loss of nigrostriatal dopamine storage capacity measured with 18F-DOPA PET were correlated.Methods17 iRBD patients, 16 PD patients with (PDRBD+) and 14 without RBD (PDRBD−), and 25 control subjects underwent 11C-MeNER PET. iRBD patients also had 18F-DOPA PET. Volume-of-interest analyses and voxel-level statistical parametric mapping were performed.ResultsPartial-volume corrected 11C-MeNER binding potential (BPND) values in M1S1 differed across the groups (P = 0.022) with the iRBD and PDRBD+ groups showing significant reductions (controls vs. iRBD P = 0.007; control vs. PDRBD+ P = 0.008). Voxel-wise comparisons confirmed reductions of M1S1 11C-MeNER binding in PD and iRBD patients. Significant correlation was seen between putaminal 18F-DOPA uptake and thalamic 11C-MeNER binding in iRBD patients (r2 = 0.343, P = 0.013).ConclusionsThis study found altered noradrenergic neurotransmission in the M1S1 cortex of iRBD patients. The observed reduction of M1S1 11C-MeNER binding in iRBD may represent noradrenergic terminal degeneration or physiological down-regulation of NARTs in this prodromal phenotype of PD. The correlation between thalamic 11C-MeNER binding and putaminal 18F-DOPA binding suggests that these neurotransmitter systems degenerate in parallel in the iRBD phenotype of prodromal PD.  相似文献   
58.
目的探讨床旁多普勒超声引导下经皮气管切开术(PDT)在重症脑出血患者中的应用价值。方法选取2014年1月—2019年4月南方医科大学附属小榄医院重症医学科监护治疗的重症脑出血患者126例,在ICU床旁采用超声引导下行PDT。术前采用超声进行检查,明确气管位置、周围组织及血管情况,确定穿刺部位及深度,指导术前气管导管退管。术中实时超声引导,确保手术安全。术后超声确认气管切开套管位置,筛查排除气胸等相关并发症。观察操作时间(从皮肤穿刺到成功置入气管套管时间)、一针穿刺成功率、置管成功率、气管插管意外脱管率;观察术中及术后并发症:出血量、血管/甲状腺损伤、气管后壁损伤、皮下气肿、气胸、低氧血症发生率等。结果126例患者手术均一次操作成功,一针穿刺成功率及置管成功率均为100%,未发生气管插管意外脱管。操作时间5~12 min,平均操作时间7.5 min。术中及术后未发生难以控制的大出血、严重低氧血症、血管/甲状腺损伤、气管后壁损伤、皮下气肿及气胸等并发症。结论对重症脑出血患者行床旁实时超声引导下行PDT,提高了手术的可视性、操作性和安全性,提高PDT成功率,降低相关并发症,具有良好的临床价值。  相似文献   
59.
Transcranial magnetic stimulation (TMS) can depolarize the neurons directly under the coil when applied to the cerebral cortex, and modulate the neural circuit associated with the stimulation site, which makes it possible to measure the neurophysiological index to evaluate excitability and inhibitory functions. Concurrent TMS and electroencephalography (TMS‐EEG) has been developed to assess the neurophysiological characteristics of cortical regions other than the motor cortical region noninvasively. The aim of this review is to comprehensively discuss TMS‐EEG research in the healthy brain focused on excitability, inhibition, and plasticity following neuromodulatory TMS paradigms from a neurophysiological perspective. A search was conducted in PubMed to identify articles that examined humans and that were written in English and published by September 2018. The search terms were as follows: (TMS OR ‘transcranial magnetic stimulation’) AND (EEG OR electroencephalog*) NOT (rTMS OR ‘repetitive transcranial magnetic stimulation’ OR TBS OR ‘theta burst stimulation’) AND (healthy). The study presents an overview of TMS‐EEG methodology and neurophysiological indices and reviews previous findings from TMS‐EEG in healthy individuals. Furthermore, this review discusses the potential application of TMS‐EEG neurophysiology in the clinical setting to study healthy and diseased brain conditions in the future. Combined TMS‐EEG is a powerful tool to probe and map neural circuits in the human brain noninvasively and represents a promising approach for determining the underlying pathophysiology of neuropsychiatric disorders.  相似文献   
60.
Most studies investigating the effect of childhood trauma on the brain are retrospective and mainly focus on maltreatment, whereas different types of trauma exposure such as growing up in a violent neighborhood, as well as developmental stage, could have differential effects on brain structure and function. The current magnetic resonance imaging study assessed the effect of trauma exposure broadly and violence exposure more specifically, as well as developmental stage on the fear neurocircuitry in 8‐ to 14‐year‐old children and adolescents (N = 69). We observed reduced hippocampal and increased amygdala volume with increasing levels of trauma exposure. Second, higher levels of violence exposure were associated with increased activation in the amygdala, hippocampus, and ventromedial prefrontal cortex during emotional response inhibition. This association was specifically observed in children younger than 10 years. Finally, increased functional connectivity between the amygdala and brainstem was associated with higher levels of violence exposure. Based on the current findings, it could be hypothesized that trauma exposure during childhood results in structural changes that are associated with later risk for psychiatric disorders. At the same time, it could be postulated that growing up in an unsafe environment leads the brain to functionally adapt to this situation in a way that promotes survival, where the long‐term costs or consequences of these adaptations are largely unknown and an area for future investigations.  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