全文获取类型
收费全文 | 22286篇 |
免费 | 1429篇 |
国内免费 | 761篇 |
专业分类
耳鼻咽喉 | 931篇 |
儿科学 | 280篇 |
妇产科学 | 136篇 |
基础医学 | 3970篇 |
口腔科学 | 300篇 |
临床医学 | 2114篇 |
内科学 | 2088篇 |
皮肤病学 | 96篇 |
神经病学 | 4559篇 |
特种医学 | 1412篇 |
外科学 | 1819篇 |
综合类 | 2059篇 |
预防医学 | 637篇 |
眼科学 | 1100篇 |
药学 | 1807篇 |
2篇 | |
中国医学 | 526篇 |
肿瘤学 | 640篇 |
出版年
2023年 | 224篇 |
2022年 | 354篇 |
2021年 | 708篇 |
2020年 | 659篇 |
2019年 | 630篇 |
2018年 | 624篇 |
2017年 | 649篇 |
2016年 | 590篇 |
2015年 | 577篇 |
2014年 | 995篇 |
2013年 | 1298篇 |
2012年 | 1009篇 |
2011年 | 1096篇 |
2010年 | 962篇 |
2009年 | 1036篇 |
2008年 | 1014篇 |
2007年 | 1070篇 |
2006年 | 993篇 |
2005年 | 807篇 |
2004年 | 786篇 |
2003年 | 668篇 |
2002年 | 583篇 |
2001年 | 511篇 |
2000年 | 529篇 |
1999年 | 462篇 |
1998年 | 436篇 |
1997年 | 434篇 |
1996年 | 338篇 |
1995年 | 369篇 |
1994年 | 298篇 |
1993年 | 281篇 |
1992年 | 308篇 |
1991年 | 275篇 |
1990年 | 247篇 |
1989年 | 221篇 |
1988年 | 217篇 |
1987年 | 191篇 |
1986年 | 174篇 |
1985年 | 303篇 |
1984年 | 243篇 |
1983年 | 178篇 |
1982年 | 199篇 |
1981年 | 184篇 |
1980年 | 164篇 |
1979年 | 143篇 |
1978年 | 95篇 |
1977年 | 80篇 |
1976年 | 78篇 |
1975年 | 33篇 |
1974年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
1.
2.
3.
目的探讨衰减伪影对冠心病患者门控心肌灌注显像(GMPI)图像质量及灌注结果的影响。资料与方法回顾性分析2020年3月—2021年3月在郑州大学第一附属医院核医学科经冠状动脉造影证实且于造影前后1周行GMPI的99例冠心病患者的图像,定性及半定量分析衰减校正前后GMPI图像结果,比较衰减校正前后左心室各壁段平均放射性计数及灌注结果的差异,进一步分析衰减校正前后灌注结果不一致部分的受检者的节段性室壁运动及增厚情况。结果与衰减校正前比较,衰减校正后左心室间隔、下后壁及侧壁的平均放射性计数较高(Z=-7.302、-8.014、-3.991,P均<0.001),心尖部较低(Z=-8.021,P<0.001)。其中女性衰减校正后前壁平均放射性计数减低(Z=-2.314,P=0.021)。男性衰减校正前后下后壁放射性计数差值明显高于女性(t=-8.408,P<0.05)。衰减校正后44%(44/99)的左前降支及37%(37/99)的右冠状动脉分支供血区域显像结果发生改变,结合超声心动图及GMPI结果显示其中85%(35/41)的左前降支及81%(29/36)的右冠状动脉分支供血区域室壁运动及室壁增厚率均正常。结论衰减伪影对GMPI的图像质量和灌注结果有较大影响,结合室壁运动和增厚情况等有助于鉴别衰减伪影,提高诊断准确度与特异度。 相似文献
4.
《Clinical neurophysiology》2021,132(10):2357-2364
ObjectivesTo investigate the subcortical somatosensory evoked potentials (SEPs) to electrical stimulation of either muscle or cutaneous afferents.MethodsSEPs were recorded in 6 patients suffering from Parkinson’s disease (PD) who underwent electrode implantation in the pedunculopontine (PPTg) nucleus area. We compared SEPs recorded from the scalp and from the intracranial electrode contacts to electrical stimuli applied to: 1) median nerve at the wrist, 2) abductor pollicis brevis motor point, and 3) distal phalanx of the thumb. Also the high-frequency oscillations (HFOs) were analysed.ResultsAfter median nerve and pure cutaneous (distant phalanx of the thumb) stimulation, a P1-N1 complex was recorded by the intracranial lead, while the scalp electrodes recorded the short-latency far-field responses (P14 and N18). On the contrary, motor point stimulation did not evoke any low-frequency component in the PPTg traces, nor the N18 potential on the scalp. HFOs were recorded to stimulation of all modalities by the PPTg electrode contacts.ConclusionsStimulus processing within the cuneate nucleus depends on modality, since only the cutaneous input activates the complex intranuclear network possibly generating the scalp N18 potential.SignificanceOur results shed light on the subcortical processing of the somatosensory input of different modalities. 相似文献
5.
《Clinical neurophysiology》2021,132(9):2003-2011
ObjectiveA large N20 and P25 of the median nerve somatosensory evoked potential (SEP) predicts short survival in amyotrophic lateral sclerosis (ALS). We investigated whether high frequency oscillations (HFOs) over N20 are enlarged and associated with survival in ALS.MethodsA total of 145 patients with ALS and 57 healthy subjects were studied. We recorded the median nerve SEP and measured the onset-to-peak amplitude of N20 (N20o-p), and peak-to-peak amplitude between N20 and P25 (N20p-P25p). We obtained early and late HFO potentials by filtering SEP between 500 and 1 kHz, and measured the peak-to-peak amplitude. We followed up patients until endpoints (death or tracheostomy) and analyzed the relationship between SEP or HFO amplitudes and survival using a Cox analysis.ResultsPatients showed larger N20o-p, N20p-P25p, and early and late HFO amplitudes than the control values. N20p-P25p was associated with survival periods (p = 0.0004), while early and late HFO amplitudes showed no significant association with survival (p = 0.4307, and p = 0.6858, respectively).ConclusionsThe HFO amplitude in ALS is increased, but does not predict survival.SignificanceThe enlarged HFOs in ALS might be a compensatory phenomenon to the hyperexcitability of the sensory cortex pyramidal neurons. 相似文献
6.
7.
《Clinical neurophysiology》2020,131(1):259-264
ObjectivesFasciculation potentials (FP) are an important consideration in the electrophysiological diagnosis of ALS. Muscle ultrasonography (MUS) has a higher sensitivity in detecting fasciculations than electromyography (EMG), while in some cases, it is unable to detect EMG-detected fasciculations. We aimed to investigate the differences of FP between the muscles with and without MUS-detected fasciculations (MUS-fas).MethodsThirty-one consecutive patients with sporadic ALS were prospectively recruited and in those, both needle EMG and MUS were performed. Analyses of the amplitude, duration, and number of phases of EMG-detected FPs were performed for seven muscles per patient, and results were compared between the muscles with and without MUS-fas in the total cohort.ResultsThe mean amplitude and phase number of FP were significantly lower in patients with EMG-detected FP alone (0.39 ± 0.25 mV and 3.21 ± 0.88, respectively) than in those with both FP and MUS-fas (1.22 ± 0.92 mV and 3.74 ± 1.39, respectively; p < 0.0001 and p = 0.017, Welch’s t-test).ConclusionSmall FP may be undetectable with MUS. MUS cannot replace EMG in the diagnostic approach for ALS.SignificanceClinicians should use a combination of EMG and MUS for the detection and quantitative analysis of fasciculation in ALS. 相似文献
8.
Qian Li Tian-Le Ma You-Qi Qiu Wen-Qiang Cui Teng Chen Wen-Wen Zhang Jing Wang Qi-Liang Mao-Ying Wen-Li Mi Yan-Qing Wang Yu-Xia Chu 《神经科学通报》2020,36(12):1484
Trigeminal neuralgia is a debilitating condition, and the pain easily spreads to other parts of the face. Here, we established a mouse model of partial transection of the infraorbital nerve (pT-ION) and found that the Connexin 36 (Cx36) inhibitor mefloquine caused greater alleviation of pT-ION-induced cold allodynia compared to the reduction of mechanical allodynia. Mefloquine reversed the pT-ION-induced upregulation of Cx36, glutamate receptor ionotropic kainate 2 (GluK2), transient receptor potential ankyrin 1 (TRPA1), and phosphorylated extracellular signal regulated kinase (p-ERK) in the trigeminal ganglion. Cold allodynia but not mechanical allodynia induced by pT-ION or by virus-mediated overexpression of Cx36 in the trigeminal ganglion was reversed by the GluK2 antagonist NS102, and knocking down Cx36 expression in Nav1.8-expressing nociceptors by injecting virus into the orofacial skin area of Nav1.8-Cre mice attenuated cold allodynia but not mechanical allodynia. In conclusion, we show that Cx36 contributes greatly to the development of orofacial pain hypersensitivity through GluK2, TRPA1, and p-ERK signaling.Electronic supplementary materialThe online version of this article (10.1007/s12264-020-00594-4) contains supplementary material, which is available to authorized users. 相似文献
9.
《Clinical neurophysiology》2021,132(12):3104-3115
ObjectiveWe aimed to establish an objective neurophysiological test protocol that can be used to assess the somatosensory nervous system.MethodsIn order to assess most fiber subtypes of the somatosensory nervous system, repetitive stimuli of seven different modalities (touch, vibration, pinprick, cold, contact heat, laser, and warmth) were synchronized with the electroencephalogram (EEG) and applied on the cheek and dorsum of the hand and dorsum of the foot in 21 healthy subjects and three polyneuropathy (PNP) patients. Latencies and amplitudes of the modalities were assessed and compared. Patients received quantitative sensory testing (QST) as reference.ResultsWe found reproducible evoked potentials recordings for touch, vibration, pinprick, contact-heat, and laser stimuli. The recording of warm-evoked potentials was challenging in young healthy subjects and not applicable in patients. Latencies were shortest within Aβ-fiber-mediated signals and longest within C-fibers. The test protocol detected function loss within the Aβ-fiber and Aδ-fiber-range in PNP patients. This function loss corresponded with QST findings.ConclusionIn this pilot study, we developed a neurophysiological test protocol that can specifically assess most of the somatosensory modalities. Despite technical challenges, initial patient data appear promising regarding a possible future clinical application.SignificanceEstablished and custom-made stimulators were combined to assess different fiber subtypes of the somatosensory nervous system using modality-specific evoked potentials. 相似文献
10.