全文获取类型
收费全文 | 27195篇 |
免费 | 2246篇 |
国内免费 | 782篇 |
专业分类
耳鼻咽喉 | 465篇 |
儿科学 | 306篇 |
妇产科学 | 579篇 |
基础医学 | 3962篇 |
口腔科学 | 319篇 |
临床医学 | 3649篇 |
内科学 | 2469篇 |
皮肤病学 | 178篇 |
神经病学 | 8261篇 |
特种医学 | 607篇 |
外科学 | 2267篇 |
综合类 | 2469篇 |
预防医学 | 944篇 |
眼科学 | 294篇 |
药学 | 1520篇 |
4篇 | |
中国医学 | 1680篇 |
肿瘤学 | 250篇 |
出版年
2024年 | 118篇 |
2023年 | 532篇 |
2022年 | 996篇 |
2021年 | 1360篇 |
2020年 | 1238篇 |
2019年 | 1052篇 |
2018年 | 988篇 |
2017年 | 1031篇 |
2016年 | 902篇 |
2015年 | 888篇 |
2014年 | 1637篇 |
2013年 | 1620篇 |
2012年 | 1278篇 |
2011年 | 1527篇 |
2010年 | 1220篇 |
2009年 | 1139篇 |
2008年 | 1169篇 |
2007年 | 1070篇 |
2006年 | 1018篇 |
2005年 | 865篇 |
2004年 | 774篇 |
2003年 | 750篇 |
2002年 | 629篇 |
2001年 | 518篇 |
2000年 | 465篇 |
1999年 | 414篇 |
1998年 | 370篇 |
1997年 | 344篇 |
1996年 | 321篇 |
1995年 | 300篇 |
1994年 | 299篇 |
1993年 | 213篇 |
1992年 | 280篇 |
1991年 | 233篇 |
1990年 | 228篇 |
1989年 | 200篇 |
1988年 | 165篇 |
1987年 | 166篇 |
1986年 | 155篇 |
1985年 | 251篇 |
1984年 | 225篇 |
1983年 | 161篇 |
1982年 | 174篇 |
1981年 | 155篇 |
1980年 | 157篇 |
1979年 | 130篇 |
1978年 | 110篇 |
1977年 | 89篇 |
1976年 | 87篇 |
1974年 | 52篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
应用拉丁方设计,在不同体重组的大鼠,于不同时辰,对交叉上核采取不同强度的刺激,用放射免疫法测定外周血中皮质酮的含量。其结果显示:各体重组间无显著性差异,不同时辰血浆皮质酮的平均含量各组呈现基本相同的节律性变化,无论何时辰刺激交叉上核使之兴奋,均可显著提高血浆皮质酮的含量。完全损毁交叉上核后72小时血浆皮质酮含量和正常对照组无显著性差异,且其节律性也没有出现明显变化。 相似文献
72.
Judith L. Black Peter R. A. Johnson Lorraine Alouan Carol L. Armour 《European journal of pharmacology》1990,180(2-3):311-317
This study investigated the effects of neurokinin A (NKA) on cholinergic neural responses in human bronchus. NKA (0.1 nM) did not alter the contractile response to submaximal electrical field stimulation. However, K+ channel blockade with 4-aminopyridine (4-AP) (0.1 mM) potentiated the response to electrical field stimulation (to 182 ± 25% of control, n = 4, P < 0.05) and subsequent addition of NKA in the presence of 4-AP produced further potentiation (to 123 ± 6% of the response to 4-AP n = 4, P < 0.05). Neither 4-AP (0.01 or 0.1 mM) nor NKA in the presence of 4-AP potentiated the actions of exogenous acetylcholine but in these experiments 4-AP itself produced a marked direct contractile response. Thus NKA in the presence of K+ channel blockade potentiates cholinergic neural response in human bronchus and this occurs at a prejunctional site. 相似文献
73.
Wang Hongdu Liou Jinjong T. C. M. Hospital Luzhou Medical College Luzhou Sichuan China 《世界针灸杂志》1993,(1)
The study has explored 11 correlative variables which might affect the gallblad-der pressure GBP of patients with gall stone after auricular electrical stimulation by means of multiplestepwise regression. It was found that the size of gallbladder stone (X9), cholecystolithiasis (X4),sex (X1), and the baseline of GBP (X10) could affect the GBP change range (Y1) depressingly orreinforcingly. Also the baseline of GBP (Y1) could be affected by the variables X1 (sex), X2 (age),and X6 (long diameter of the gallbladder, LDGB), etc.. The result shows that the change in GBPafter auricular electrical stimulation is comprehensively influenced by multiple factors. And it providessome useful information for predicting the curative effect of auricular therapy on gallbladder stone inclinic. 相似文献
74.
NESTOR G. SEPULVEDA Ph.D. JOHN P. WIKSWO Jr. Ph.D. 《Journal of cardiovascular electrophysiology》1994,5(3):258-267
Bipolar Stimulation of the Cardiac Bidomain. Introduction: One of the fundamental electrophysiologic problems that has not yet been completely elucidated is the response of cardiac tissue to externally applied electric currents. A limited number of theoretical and experimental techniques has been used to study the electric behavior of cardiac tissue in the presence of stimulating currents, and to demonstrate that the anisotropy in the passive electrical properties of the tissue plays an important role in the genesis and propagation of the activation wave-front and the resulting potential distributions.
Methods and Results: In this work we have applied the finite element method to study the electric and magnetic fields produced by cardiac tissue in response to bipolar current injection, using a linear bidomain model to represent the tissue. We found that the transmembrane potential distribution close to the stimulus electrode has a rather complex geometrical pattern, with adjacent hyperpolarized and depolarized regions.
Conclusion: This behavior is consistent with previous theoretical and experimental results and may have implications in the study of electrical stimulation of cardiac tissue that are not apparent using other models. 相似文献
Methods and Results: In this work we have applied the finite element method to study the electric and magnetic fields produced by cardiac tissue in response to bipolar current injection, using a linear bidomain model to represent the tissue. We found that the transmembrane potential distribution close to the stimulus electrode has a rather complex geometrical pattern, with adjacent hyperpolarized and depolarized regions.
Conclusion: This behavior is consistent with previous theoretical and experimental results and may have implications in the study of electrical stimulation of cardiac tissue that are not apparent using other models. 相似文献
75.
M. V. Merrick T. M. Griffin 《European journal of nuclear medicine and molecular imaging》1994,21(6):521-524
The effect of swallowing a small quantity of water or of solid food (biscuit) on the renogram curve was observed in 177 patients. Swallowing provoked contraction of the renal pelvis in 63% of the kidneys with a pelvicalyceal system which was neither obstructed nor dilated, with expulsion of a substantial fraction of the contents within 30 s. This did not occur in obstructed or denervated kidneys, nor in patients with a high transection of the spinal cord. Evidence is adduced that this contraction is mediated reflexly. This effect may be used diagnostically to distinguish physiological dilatation from obstruction. The implications when performing and interpreting renography are discussed.
Correspondence to: M.V. Merrick 相似文献
76.
Anna Kostopoulou Eftihia Sbarouni Efthimios G Livanis George N Theodorakis Dimitrios Kremastinos 《Europace : European pacing, arrhythmias, and cardiac electrophysiology》2004,6(3):205-208
We describe the case of a recipient of an implantable cardioverter defibrillator with multiple syncopal episodes due both to superior vena cava obstruction and electrical instability. These complications occurred in the presence of two transvenous implantable cardioverter defibrillator leads. The patient has been managed conservatively with anticoagulants and new antiarrhythmic drugs with improvement in both his clinical problems. 相似文献
77.
The purpose of this study was to determine whether the late component of somatosensory evoked potentials (SEP) induced by electrical tooth stimulation and pain intensity are inhibited by heterotopic ischemic stimulation. The tourniquet pressure with 50 mmHg greater than the individual's systolic pressure was applied to the left upper arm for 10 min as ischemic conditioning stimulation. The late component of SEP and visual analogue scale (VAS) were recorded at 4 times and both were significantly decreased when ischemic conditioning stimulation was applied. The maximum reductions in SEP amplitude and the VAS value were 26.1% and 21.2%, respectively, during ischemic conditioning stimulation. After-effect was observed 5 min after removal of the conditioning stimulation. The present study revealed that heterotopic ischemic stimulation attenuated the late component of SEP induced by electrical tooth stimulation, triggering diffuse noxious inhibitory controls (DNIC) and after-effects in the trigeminal nerve territory. It was also suggested that the DNIC effect differs, depending on the intensity, kind, and quality of the test and conditioning stimuli. 相似文献
78.
79.
Deep brain stimulation, DBS, is an accepted technique for the treatment of Parkinson's disease. DBS affects the electrical functions of neurons, but exactly how it alters those functions is not clearly explained. An electrical model is determined to simulate treatment with DBS of the sub thalamic nucleus. This model shows the difference in electrical fields between the inside and the outside the neurons. The generated electrical field near the electrodes is high enough to perform an electropermeabilization of the cell membranes, which most likely blockade normal nerve pulses or reduce the nerve impulse speed. Further away from the electrodes activation of large axons is performed. 相似文献
80.
Jie-Yuan Li Alberto J Espay Carolyn A Gunraj Pramod K Pal Danny I Cunic Anthony E Lang Robert Chen 《Movement disorders》2007,22(6):813-821
Mirror movements (MM) occur in early, asymmetric Parkinson's disease (PD). To examine the pathophysiology of MM in PD, we studied 13 PD patients with MM (PD-MM), 7 PD patients without MM (PD-NM), and 14 normal subjects. Cross-correlogram did not detect common synaptic input to motoneuron pools innervating homologous hand muscles in PD-MM patients. Transcranial magnetic stimulation studies showed no significant difference in ipsilateral motor-evoked potentials between PD-MM patients and normal subjects. The MM side of PD-MM patients showed a slower increase in ipsilateral silent period area with higher level of muscle contraction than the non-MM side and normal subjects. There was less interhemispheric inhibition (IHI) at long interstimulus intervals of 20 to 50 ms in PD-MM than PD-NM. IHI reduced short interval intracortical inhibition in normal subjects and PD-NM, but not in PD-MM. IHI significantly increased intracortical facilitation in PD-MM and PD-NM patients, but not in normal subjects. Our results suggest that MM in PD is due to activation of the contralateral motor cortex. PD-MM patients had reduced transcallosal inhibitory effects on cortical output neurons and on intracortical inhibitory circuits compared to PD-NM patients and controls. These deficits in transcallosal inhibition may contribute to MM in PD patients. 相似文献