全文获取类型
收费全文 | 3451730篇 |
免费 | 247389篇 |
国内免费 | 6119篇 |
专业分类
耳鼻咽喉 | 47027篇 |
儿科学 | 112624篇 |
妇产科学 | 94009篇 |
基础医学 | 498792篇 |
口腔科学 | 98291篇 |
临床医学 | 313699篇 |
内科学 | 664386篇 |
皮肤病学 | 77037篇 |
神经病学 | 272371篇 |
特种医学 | 129171篇 |
外国民族医学 | 693篇 |
外科学 | 518336篇 |
综合类 | 76023篇 |
现状与发展 | 14篇 |
一般理论 | 1255篇 |
预防医学 | 267440篇 |
眼科学 | 82722篇 |
药学 | 254805篇 |
13篇 | |
中国医学 | 7545篇 |
肿瘤学 | 188985篇 |
出版年
2021年 | 26892篇 |
2019年 | 27780篇 |
2018年 | 39061篇 |
2017年 | 29478篇 |
2016年 | 32932篇 |
2015年 | 37186篇 |
2014年 | 52405篇 |
2013年 | 78201篇 |
2012年 | 107870篇 |
2011年 | 114339篇 |
2010年 | 68226篇 |
2009年 | 64001篇 |
2008年 | 106775篇 |
2007年 | 113779篇 |
2006年 | 115043篇 |
2005年 | 111030篇 |
2004年 | 106799篇 |
2003年 | 102381篇 |
2002年 | 98835篇 |
2001年 | 163009篇 |
2000年 | 167346篇 |
1999年 | 140351篇 |
1998年 | 39864篇 |
1997年 | 34853篇 |
1996年 | 35046篇 |
1995年 | 33249篇 |
1994年 | 30572篇 |
1993年 | 28583篇 |
1992年 | 108242篇 |
1991年 | 105204篇 |
1990年 | 101938篇 |
1989年 | 98357篇 |
1988年 | 90196篇 |
1987年 | 88287篇 |
1986年 | 83049篇 |
1985年 | 79481篇 |
1984年 | 59009篇 |
1983年 | 50282篇 |
1982年 | 29364篇 |
1979年 | 53684篇 |
1978年 | 37852篇 |
1977年 | 31788篇 |
1976年 | 30144篇 |
1975年 | 32053篇 |
1974年 | 38828篇 |
1973年 | 37182篇 |
1972年 | 34707篇 |
1971年 | 32632篇 |
1970年 | 30277篇 |
1969年 | 28628篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
Induction of endothelium-dependent relaxation in the rat aorta by IRL 1620, a novel and selective agonist at the endothelin ETB receptor. 总被引:3,自引:2,他引:1
下载免费PDF全文
![点击此处可从《British journal of pharmacology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
H. Karaki S. A. Sudjarwo M. Hori M. Takai Y. Urade T. Okada 《British journal of pharmacology》1993,109(2):486-490
1. The effects of a novel and selective agonist at the endothelin ETB receptor, IRL 1620 (Suc-[Glu9, Ala11,15] endothelin-1 (8-21)), were examined in the isolated aorta of the rat. 2. IRL 1620 (1-300 nM) changed neither the resting tone nor the cytosolic Ca2+ level ([Ca2+]i) of the aorta without endothelium. In the presence of endothelium, however, IRL 1620 increased endothelial [Ca2+]i with little effect on the muscle tone. In the absence of external Ca2+, IRL 1620 still induced a transient increase in endothelial [Ca2+]i. 3. Noradrenaline (100 nM) increased both muscle [Ca2+]i and tension. IRL 1620 (1-300 nM) relaxed the muscle with an increase in endothelial [Ca2+]i only in the presence of endothelium. An inhibitor of nitric oxide synthase, 100 microM NG-monomethyl-L-arginine, inhibited the relaxant effect of IRL 1620 but not the increase in endothelial [Ca2+]i. 4. In resting and noradrenaline-stimulated aorta, the effects of IRL 1620 were inhibited by a selective antagonist of the ETB receptor, IRL 1038 (0.3-3 microM), although a selective antagonist of the ETA receptor, BQ-123 (3 microM), was ineffective. Verapamil (10 microM) did not alter the effects of IRL 1620. 5. A muscarinic receptor agonist, carbachol (1 microM), also induced endothelium-dependent relaxation with an increase in endothelial [Ca2+]i. However, the effects of carbachol were not inhibited by the ETB antagonist, IRL 1038 (3 microM).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
993.
Ihsan A. Badr 《International ophthalmology》1993,17(3):155-160
The region is characterized by diversity in cultural, political, economic and health conditions. Blindness in the region varies from 6.4% to 0.2% with cataract ranking highly as an underlying cause. There is a need to develop national policies to deliver affordable, technically suitable, and cost effective management plans to reduce cataract. Economic, demographic, health, and manpower statistics are essential information to be considered in formulating such policies. 相似文献
994.
Role of intracortical mechanisms in the late part of the silent period to transcranial stimulation of the human motor cortex 总被引:3,自引:0,他引:3
J.P. Brasil-Neto A. Cammarota J. Valls-Solé A. Pascual-Leone M. Hallett L. G. Cohen 《Acta neurologica Scandinavica》1995,92(5):383-386
Transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (TES) of the human motor cortex produce a silent period (SP) following motor evoked potentials (MEPs). The early part of the SP can be explained by decreased alpha motor neuron excitability, whereas the late part is presumably due to suprasegmental mechanisms. In order to determine the level of the suprasegmental contribution to the generation of SPs, we recorded excitatory and inhibitory responses to TMS, TES, and percutaneous electrical brainstem stimulation (PBS) in the voluntarily activated first dorsal interosseous muscle of the hand. Stimulus intensities were set so that PBS and TES induced MEPs with areas equal to or larger than those of MEPs obtained with TMS. This procedure revealed that SPs were 49% and 83% shorter with TES and PBS, respectively, than with TMS. As TMS is more effective than TES or PBS in activating cortical interneurons, these findings support the idea that a significant component of the SP arises from intracortical mechanisms. 相似文献
995.
Large granular lymphocyte expansions in patients with Felty's syndrome: analysis using anti-T cell receptor V beta-specific monoclonal antibodies. 总被引:5,自引:0,他引:5
下载免费PDF全文
![点击此处可从《Clinical and experimental immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
S J Bowman M Bhavnani G C Geddes V Corrigall A W Boylston G S Panayi J S Lanchbury 《Clinical and experimental immunology》1995,101(1):18-24
Felty's syndrome (FS), the association of rheumatoid arthritis (RA) and idiopathic neutropenia, remains an unexplained phenomenon. HLA-DR4 is found in over 90% of cases. Patients with FS may have a T cell lymphocytosis of CD3+CD8+CD57+ large granular lymphocytes (LGL syndrome). In this study of 47 patients with FS, 19% had clear evidence for LGL expansions, while in total 42% had variable evidence for the LGL syndrome using currently available techniques. Of these T cell expansions, 76% were clonal, as demonstrated by Southern blotting and analysis with T cell receptor (TCR) beta chain constant region probes. This technique may fail to detect clonal populations in some patients. Cytofluorographic analysis using antibodies specific for TCR V beta chains identified patients with clonal LGL expansions with results comparable to those obtained with Southern blotting. No evidence for shared V beta usage among expansions from different patients was seen. The role of LGL in RA and FS is currently unclear, but this technique offers a practical and accessible means of identifying patients with LGL expansions, as a starting point for further investigation. 相似文献
996.
Case report 506 总被引:1,自引:0,他引:1
F. Bertoni M.D. V. Zucchi M.D. S. Mapelli M.D. P. Bacchini M.D. 《Skeletal radiology》1988,17(7):522-526
997.
In 82 CHD male patients aged 35-54 years with well-preserved working capacity (threshold load, 600-750 kgm/min) who had underwent bicycle ergometer test, the time course of changes in the major hemodynamic parameters was found to be significantly similar to that of healthy individuals. The cases who stopped performing bicycle ergometer tests because of anginal attacks, and ST segment depression or either showed a more significant elevation in systolic and diastolic blood pressure at the maximum load rate and lower increase in heart rate than in healthy subjects, which may be regarded as a compensatory mechanism that prevents a further decrease in coronary flow. Diminished increase in stroke index and cardiac index suggests reduced myocardial contractility. 相似文献
998.
Electrocardiographic symptoms were evaluated in 53 patients with an additional left-ventricular chorda (ALVC), detected by two-dimensional echocardiography. Signs of early ventricular repolarization (EVR) were identified in 45 (84.9%) patients. A transverse ALVC was more common in EVR-free patients (87.5%), as compared to patients with ALVC + EVR combinations (51.1%; p less than 0.05). 相似文献
999.
1000.
We compared the effects of alpha 2- and beta-adrenoreceptor blockade on the central actions of catecholamines and metabolites of alpha-methyldihydroxyphenylalanine, epinephrine, alpha-methylnorepinephrine, and alpha-methylepinephrine were studied. I.c.v. and nucleus tractus solitarii (NTS) injections were carried out under anesthesia. Following i.c.v. injection, both epinephrine and methylepinephrine rapidly reduced blood pressure and heart rate, but the effects of methylnorepinephrine occurred somewhat later. Following microinjection into the nucleus of the solitary tract, epinephrine, methylepinephrine, and methylnorepinephrine all caused hypotension and bradycardia. The hypotensive effects of all 3 amines in the NTS were attenuated in additive fashion by yohimbine, an alpha 2 adrenoreceptor antagonist, and timolol, a beta-adrenoreceptor antagonist, whereas only yohimbine attenuated the bradycardia. The combination of yohimbine and timolol abolished the effects of the amines. These data suggest that in the NTS both alpha 2 and beta adrenoreceptor stimulation contribute to the hypotensive effects of these amines, but that only alpha 2 adrenoreceptors are principally involved in the heart rate response. 相似文献