全文获取类型
收费全文 | 47127篇 |
免费 | 3168篇 |
国内免费 | 1111篇 |
专业分类
耳鼻咽喉 | 1447篇 |
儿科学 | 952篇 |
妇产科学 | 513篇 |
基础医学 | 5599篇 |
口腔科学 | 729篇 |
临床医学 | 6499篇 |
内科学 | 7152篇 |
皮肤病学 | 330篇 |
神经病学 | 2732篇 |
特种医学 | 3261篇 |
外国民族医学 | 4篇 |
外科学 | 4392篇 |
综合类 | 6923篇 |
现状与发展 | 1篇 |
预防医学 | 2780篇 |
眼科学 | 997篇 |
药学 | 4363篇 |
23篇 | |
中国医学 | 1332篇 |
肿瘤学 | 1377篇 |
出版年
2024年 | 80篇 |
2023年 | 528篇 |
2022年 | 994篇 |
2021年 | 1432篇 |
2020年 | 1416篇 |
2019年 | 1271篇 |
2018年 | 1292篇 |
2017年 | 1299篇 |
2016年 | 1336篇 |
2015年 | 1430篇 |
2014年 | 2707篇 |
2013年 | 2927篇 |
2012年 | 2676篇 |
2011年 | 2742篇 |
2010年 | 2215篇 |
2009年 | 2025篇 |
2008年 | 2146篇 |
2007年 | 2191篇 |
2006年 | 1978篇 |
2005年 | 1774篇 |
2004年 | 1674篇 |
2003年 | 1427篇 |
2002年 | 1346篇 |
2001年 | 1260篇 |
2000年 | 1059篇 |
1999年 | 984篇 |
1998年 | 964篇 |
1997年 | 924篇 |
1996年 | 834篇 |
1995年 | 812篇 |
1994年 | 688篇 |
1993年 | 570篇 |
1992年 | 524篇 |
1991年 | 427篇 |
1990年 | 370篇 |
1989年 | 351篇 |
1988年 | 316篇 |
1987年 | 261篇 |
1986年 | 224篇 |
1985年 | 346篇 |
1984年 | 259篇 |
1983年 | 183篇 |
1982年 | 228篇 |
1981年 | 174篇 |
1980年 | 165篇 |
1979年 | 125篇 |
1978年 | 101篇 |
1977年 | 92篇 |
1976年 | 91篇 |
1974年 | 43篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
M. R. Wang C. Y. Chai J. S. Kuof 《Clinical and experimental pharmacology & physiology》1994,21(1):21-29
1. In chloralose-urethane anaesthetized cats, the dorsal cardiovascular reactive area (DCRA) in the parvocellular reticular nucleus dorsomedial to the facial nucleus, and the ventral cardiovascular reactive area (VCRA) ventromedial to the facial nucleus, were stimulated by microinjections of sodium glutamate (100–200 nmol) or electric current. 2. Stimulation of DCRA, with a long latency of 15–20 s, elicited a marked increase of blood flow in the contralateral femoral artery with little change to moderate increase in systemic arterial blood pressure (ABP). In the relatively dorsal portion of DCRA, however, a smaller increase of blood flow in the ipsilateral femoral artery was elicited. 3. On the other hand, stimulation of VCRA with a short latency (3–5 s) evoked an increase of blood flow in both femoral arteries which was more prominent on the contralateral side. The responses were accompanied with decreases in the blood flow of other vascular beds with only a slight increase or minimal change in ABP. 4. The data suggest that DCRA and VCRA are both viscerotopically organized to alter the resistance of individual vascular beds for redistribution of blood flow. 相似文献
112.
Clinical correlates of high signal lesions on magnetic resonance imaging in Alzheimer's disease 总被引:1,自引:0,他引:1
David A. Bennett David W. Gilley Robert S. Wilson Michael S. Huckman Jacob H. Fox 《Journal of neurology》1992,239(4):186-190
Summary The pathophysiology and clinical significance of high signal lesions, visualized on magnetic resonance imaging (MRI) in patients with Alzheimer's disease (AD), remain controversial. Since they are known to correlate with vascular disease and vascular risk factors, we reviewed the clinical correlates of periventricular high signal (PVH) and subcortical white matter lesions (WML) in a sample of 106 patients with probable AD, excluding persons with treated vascular risk factors or symptomatic cerebrovascular and cardiovascular disease. Grade 2 PVH were seen in 26 (25%) and scattered WML were identified in 29 (18%). PHV were associated with advancing age and gait disturbance. WML were associated with gait disturbance and incontinence. Neither radiologic finding was related to dementia severity. The findings suggest that these lesions are common in patients with AD even when those with evidence of cerebrovascular disease are excluded; their presence, therefore, should not preclude a diagnosis of AD. Additionally, the data suggest that HSL on MRI may be one of many risk factors associated with functional disability in persons with probable AD. 相似文献
113.
本文介绍一种使继发性唇裂鼻畸形获得较好外形的新手术方法。术式包括切除偏曲的鼻中隔软骨,并将一片硅胶植入于中央作为鼻小柱支柱,从而矫正歪斜的鼻小柱和抬高鼻尖,使两侧鼻孔形态对称一致,用本法为11例单侧唇裂畸形较重者进行了整复,随访4个月至4年半。绝大多数(10/11)取得满意效果,未见有严重感染和变形等并发症。 相似文献
114.
David Langton Diana Way Lisbeth Trigg Duncan Blake Barry McGrath 《Clinical and experimental pharmacology & physiology》1990,17(3):219-223
1. The effects of graded treadmill exercise on renal blood flow (RBF) were examined in seven rabbits, in which congestive heart failure (CHF) was produced by the administration of doxorubicin, 1 mg/kg, twice weekly for 8 weeks, and in seven controls. A third group of five rabbits underwent doxorubicin treatment with the addition of surgical section of the left renal sympathetic nerve. 2. During submaximal exercise, there was a small reduction in RBF in controls, which was greatly exaggerated in CHF. 3. In both control and heart failure rabbits, there was a precipitous fall in RBF as exercise fatigue developed. 4. Renal sympathectomy ablated these changes in RBF during exercise. 5. It is concluded that in heart failure there is an exaggerated, sympathetically mediated, diversion of blood flow away from the kidney. The onset of exercise fatigue in both normal and heart failure rabbits is accompanied by a marked intensification of this process. 相似文献
115.
T. Urano Y. Shibayama K. Fukunishi K. Nariyama N. Ohsawa 《Virchows Archiv : an international journal of pathology》1996,427(6):607-612
We examined the effect of interruption of pulmonary arterial flow and inadequate ventilation on the development of pulmonary infarction in rats. Pulmonary arterial flow was blocked by the injection of agar into the inferior vena cava and inadequate ventilation was produced by obstructing the left main bronchus with a polypropylene tip. Histological and angiographic examination of the lung demonstrated that: pulmonary artery embolism alone does not induce pulmonary infarction; obstruction of a bronchus does not induce significant changes, but that pulmonary infarction develops when pulmonary artery embolism and obstruction of a bronchus occur simultaneously. It has been thought that pulmonary infarction is caused by acute obstruction of a pulmonary artery, however, the alveolar walls are supplied with oxygen by both the pulmonary circulation and by ventilation. Interruption of pulmonary arterial flow alone is probably not sufficient to induce pulmonary infarction, which is probably caused by deficiency of oxygen supply to the alveolar walls by a synergy between interruption of pulmonary arterial flow and inadequate ventilation. 相似文献
116.
高频超声检测颈动脉内膜-中层厚度及外周血管内皮功能评价动脉粥样硬化 总被引:1,自引:0,他引:1
目的 探讨高频超声检测颈动脉内膜-中层厚度与肱动脉内皮依赖性舒张功能在动脉粥样硬化中的诊断价值.方法 冠状动脉造影的老年患者69例及青年志愿者20例,分别行颈动脉超声检查,同时采用充气加压法测定肱动脉血流介导的内径扩张值,超声测值与冠脉造影结果对照分析.结果 ①颈动脉内膜-中层厚度值随粥样硬化斑块的增多、冠脉狭窄程度的加重而增高;②动脉粥样硬化患者在内膜-中层厚度值增高之前即可出现内皮功能损伤,肱动脉内径扩张值降低早于内膜-中层厚度值增高之前出现,内径扩张值随冠脉狭窄程度加重而下降.结论 高频超声检测颈动脉内膜-中层厚度、内径扩张值诊断早期动脉粥样硬化敏感性高,并且有助于对冠脉狭窄程度作出判断. 相似文献
117.
HIPDM single photon emission computed tomography brain imaging in partial onset secondarily generalized tonic-clonic seizures 总被引:3,自引:3,他引:0
HIPDM-Single photon emission computed tomography brain imaging was performed during interictal and ictal stages in three patients with complex partial seizures and secondarily generalized tonic-clonic seizures. In all three patients, interictal studies demonstrated decreased regional cerebral perfusion (rCP) and ictal studies showed increased rCP in the epileptogenic region. The demonstration of focal hyperperfusion by SPECT performed during secondarily generalized tonic-clonic seizures suggests that rCP in the epileptic focus remains higher than in other cerebral regions during immediate postictal stages, even in secondarily generalized seizures. 相似文献
118.
Benjamin H. S. Lau Sharon K. Riesen Kim P. Truong Esther W. Lau Peter Rohdewald Ray A. Barreta 《The Journal of asthma》2004,41(8):825-832
A randomized, placebo-controlled, double-blind study involving 60 subjects, aged 6-18 years old, was conducted over a period of 3 months to determine the effect of Pycnogenol® (a proprietary mixture of water-soluble bioflavonoids extracted from French maritime pine) on mild-to-moderate asthma. After baseline evaluation, subjects were randomized into two groups to receive either Pycnogenol® or placebo. Subjects were instructed to record their peak expiratory flow with an Assess® Peak Flow Meter each evening. At the same time, symptoms, daily use of rescue inhalers (albuterol), and any changes in oral medications were also recorded. Urine samples were obtained from the subjects at the end of the run-in period, and at 1-, 2-, and 3-month visits. Urinary leukotriene C4/D4/E4 was measured by an enzyme immunoassay. Compared with subjects taking placebo, the group who took Pycnogenol® had significantly more improvement in pulmonary functions and asthma symptoms. The Pycnogenol® group was able to reduce or discontinue their use of rescue inhalers more often than the placebo group. There was also a significant reduction of urinary leukotrienes in the Pycnogenol® group. The results of this study demonstrate the efficacy of Pycnogenol® as an adjunct in the management of mild-to-moderate childhood asthma. 相似文献
119.
不同海拔高度严重烧伤延迟复苏大鼠脑组织中能量负荷的变化及其意义 总被引:2,自引:2,他引:0
目的:探讨不同海拔高度严重烧伤延迟复苏大鼠脑组织能量负荷变化及其意义。方法:以120只雄性Wistar大鼠建立高原(海拔3800m)实验模型(TBSA30%,Ⅲ度),随机分为延迟、即时复苏组和正常对照组,分别于伤后1、6、12、24、72h及7d取材。兰州地区取相等数量动物重复实验。应用高效液相色谱法检测脑组织中AMP、ADP、ATP的含量,并计算能量负荷。结果:能量负荷在高原正常对照组与兰州地区正常对照组差异显著(P〈0.01)。高原烧伤后脑组织能量负荷与对照组相比均降低,即时复苏组伤后早期即出现显著变化(P〈0.01),伤后72h开始恢复,伤后7d差异无显著,延迟复苏组伤后7d仍星显著差异(P〈0.01)。与即时复苏组比较伤后6~24h无显著差异,伤后72h~7d呈显著性差异(P〈0.01)。高原地区各时相点与兰州地区比较,EC值均降低,除即时复苏组6h外,具有统计学意义。结论:不同海拔高度严重烧伤延迟复苏大鼠脑组织能量负荷的改变一定程度上反映了脑损伤的严重程度。 相似文献
120.
原发性肝癌患者肝切除术前、后免疫细胞表型分析 总被引:1,自引:1,他引:0
目的研究原发性肝癌(PrimaryLiverCarcinoma,PLC)患者肝切除术前、后免疫细胞表型的变化。方法采用直接免疫荧光标记,流量血细胞计数法(FlowCytometry,FCM)检测方法,动态观察120例PLC患者肝切除术前后外周血T淋巴细胞亚群、NK细胞和HLA鄄DR含量变化。结果肝切除术前肝功能Child鄄PughB级、OGTTL型和术前施行肝动脉栓塞化疗患者外周血CD8+T细胞含量明显低于正常人组,CD4+/CD8+比值则较高(P<0郾05)。全部肝癌患者肝切除术前、后CD3+CD4+T细胞和NK细胞(CD3-CD16+CD56+)含量无明显差异。术后第1天、第3天、第7天和第2周外周血淋巴细胞CD3+CD8+含量明显低于肝切除术前和术后第3周(P<0.01);而CD4+/CD8+比值则显著高于肝切除术前和术后第3周(P<0郾01)。结论PLC合并肝硬变肝储备功能不足、术前肝动脉栓塞化疗和肝切除术可导致机体细胞免疫功能低下,PLC患者肝切除术前行肝动脉栓塞化疗的价值有待深入研究。 相似文献