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   478篇
  免费   7篇
  国内免费   4篇
耳鼻咽喉   2篇
儿科学   9篇
妇产科学   1篇
基础医学   66篇
口腔科学   5篇
临床医学   51篇
内科学   61篇
神经病学   41篇
特种医学   2篇
外科学   37篇
综合类   51篇
预防医学   6篇
眼科学   4篇
药学   146篇
  1篇
中国医学   5篇
肿瘤学   1篇
  2022年   7篇
  2021年   4篇
  2020年   4篇
  2019年   8篇
  2018年   7篇
  2016年   3篇
  2015年   4篇
  2014年   17篇
  2013年   20篇
  2012年   13篇
  2011年   21篇
  2010年   10篇
  2009年   13篇
  2008年   13篇
  2007年   19篇
  2006年   19篇
  2005年   10篇
  2004年   7篇
  2003年   5篇
  2002年   10篇
  2001年   6篇
  2000年   8篇
  1999年   4篇
  1998年   5篇
  1997年   7篇
  1996年   12篇
  1995年   14篇
  1994年   13篇
  1993年   14篇
  1992年   17篇
  1991年   14篇
  1990年   14篇
  1989年   12篇
  1988年   20篇
  1987年   8篇
  1986年   11篇
  1985年   6篇
  1984年   6篇
  1983年   6篇
  1982年   8篇
  1981年   3篇
  1980年   9篇
  1979年   4篇
  1978年   5篇
  1977年   6篇
  1976年   10篇
  1975年   5篇
  1974年   8篇
  1973年   8篇
  1971年   4篇
排序方式: 共有489条查询结果,搜索用时 15 毫秒
31.
Summary A typical shiftwork experiment was chosen to prove the validity of an automated procedure for the analysis of free noradrenaline and adrenaline in urine. The method consists of a column switching technique with an adsorption/elution clean-up and a reversed phase high performance liquid chromatography followed by chemical reaction detection based on the trihydroxyindole method. The analysis of variance was performed using a second data set obtained by a semi-automated procedure for which the accuracy had already been confirmed. The analysis of covariance showed that for field studies, as well as for laboratory experiments in which the variances contributed by the experiments themselves are greater than 10% rel., the data sets of the two methods provide the same information.Dedicated to Prof. H. Hartkamp, University of Wuppertal, on the occasion of his 60th birthday  相似文献   
32.
采用硫代巴比妥酸(TBA)显色法测定肾上腺素(adrenalAdr)致室性心律失常(VA)后血浆及组织匀浆中脂质过氧化物(LPO)的代谢产物丙二醛(MDA)的含量,观察西米替丁(cimetidineCim)对其含量的影响。结果发现Adr诱发家兔VA后血浆及组织匀浆中MDA含量明显增加,Cim37.5mg/kgiv,能明显降低VA的发生率,推迟VA发作的时间,缩短其持续时间,并能显著抑制MDA生成。提示Adr致VA后体内脂质过氧化过程加强,Cim抗脂质过氧化可能与抗心律失常作用有关。  相似文献   
33.
动物实验初步证明黄连素可明显对抗氯仿联合肾上腺素、乌头碱以及氯仿所诱发的心律失常,与已知的抗心律失常药物的作用无明显差异。但黄连素延长哇巴因对豚鼠的致死时间作用不及苯英钠、奎尼丁及心得安等药物。  相似文献   
34.
The aim of the present study was to investigate the influence of insulin-induced hypoglycaemia on platelet sensitivity to adrenaline and non-adrenergic agonists in man. Twenty-five healthy male subjects volunteered for the study. To evaluate the effects on platelets of different insulin-adrenaline interrelationships, two experimental models were used. In the first, hypoglycaemia was induced by a 60-min IV infusion of human insulin at the rate of 64 mU m-2 min-1, whereas in the other the same insulin dose was administered as an IV bolus (3.84 U m-2). Throughout the studies, plasma glucose, insulin, and adrenaline were measured together with platelet sensitivity to adrenaline, ADP, platelet activating factor, collagen, and sodium arachidonate. In both studies, hypoglycaemia induced a reduction of platelet sensitivity to adrenaline (p = 0.006 in infusion and p = 0.045 in injection study). In particular, maximal aggregation to adrenaline fell from 47.9 +/- 9.9 (+/- SE) to 31.1 +/- 11.3% at the hypoglycaemic nadir in the infusion study, and from 64.6 +/- 8.2 to 34.6 +/- 10.3% at the hypoglycaemic nadir in the injection study. In the injection study an increase of platelet sensitivity to ADP (p = 0.05), platelet activating factor (p = 0.018), sodium arachidonate (p = 0.035), and collagen (p = 0.027) was also found, in agreement with observations already published using the infusion protocol. Thus, insulin-induced hypoglycaemia increases platelet sensitivity to non-adrenergic agonists and decreases platelet response to adrenaline.  相似文献   
35.
To investigate whether the brain adrenergic and cholinergic neurotransmitter systems are involved in the regulation of 2-deoxy-d-glucose (2-DG)-induced hyperglycemia, we studied the effects of adrenergic and cholinergic antagonists on 2-DG-induced secretion of epinephrine and glucagon, and hyperglycemia, in anesthetized fed rats. When 2-DG (10 mg/10 μl) was injected into the third cerebral ventricle, hepatic venous plasma glucose, glucagon, and epinephrine concentrations were significantly increased. Co-administration of phentolamine, propranolol, atropine and hexamethonium (1 × 10−7 mol) with 2-DG did not modify the hyperglycemia responses normally observed after the administration of 2-DG alone. From this evidence we concluded that neither brain adrenoceptive nor cholinoceptive neurons are involved in the regulation of 2-DG-induced hyperglycemia.  相似文献   
36.
Platelets are involved in the pathogenesis of vascular damage in both atherosclerosis and arterial hypertension. Their reactivity in vivo is influenced by different factors, including sympathoadrenal activation, plasma levels of atherogenic lipoproteins and haemorrheological changes. In the present review, we examine the modulation of platelet function by the sympathoadrenal system and concentrate on the role of circulating catecholamines in the control of platelet responses. Human platelets exhibit both adrenergic and dopaminergic receptors that are influenced by different catecholamines. α2-Adrenoceptors of α2A subtype prevail on platelet membrane; through their stimulation, catecholamines potentiate the effects of other agonists and, at higher concentrations, initiate platelet responses, including aggregation, secretion and arachidonate pathway activation. Physiological and pathological conditions causing sympathoadrenal activation in vivo , i.e. physical activity, mental stress, insulin-induced hypoglycaemia, acute coronary ischaemia and heart failure, modify the circulating platelet populations and modulate platelet reactivity through an increase in circulating catecholamines. A sympathoadrenal hyperactivation modifies the function of circulating platelets through direct catecholamine effects, catecholamine-induced changes of haemodynamic factors and lipid pattern and inhibition of the vascular eicosanoid synthesis. The catecholamine effects on platelet function can be involved in the interplay among stress, adrenomedullary system activation and cardiovascular diseases.  相似文献   
37.
Essential hyperhidrosis (EH) is caused by a poorly understood overactivity of the sympathetic fibres passing through the upper dorsal sympathetic ganglia D2 and D3. These ganglia are also in the pathway of the sympathetic innervation of the heart and lungs. Therefore, although the predominant sympathetic neurotransmitter at the eccrine sweat glands is acetylcholine, the plasma concentration of noradrenaline (NA) (which is the main sympathetic neurotransmitter at the end organs including the heart and the lungs) may be elevated. Furthermore, as there are some indications for generalized sympathetic overactivity in EH, the plasma concentration of adrenaline (A) may also be elevated. Plasma levels of NA and A were therefore determined in 13 EH patients before and after thoracoscopic D2–D3 sympathicolysis (TS). Preoperative NA and A plasma levels were all within the normal limits used in our laboratory. After TS, mean NA plasma levels are significantly decreased, whereas mean A are unchanged. We conclude that sympathetic overactivity in EH is limited to the upper dorsal sympathetic ganglia and that some of the cardiovascular and pulmonary effects that are observed after TS may be associated with the decrease in NA.  相似文献   
38.
Abstract. Patients with Bartter's syndrome exhibit an increased vascular resistance to the pressor effects of angiotensin II and noradrenaline. Further, an increased production of vasodilating renal prosta-glandins, perhaps mediating the vascular unresponsi-veness, has been hypothesized in this syndrome based on high urinary prostaglandins. To determine whether different peptides might contribute to blood pressure control in this syndrome, the basal immunoreactive plasma levels of an array of vasoactive peptides and catecholamines were analysed in six patients with Bartter's syndrome. Among the vasoconstrictors analyzed, the mean plasma levels of noradrenaline (NA), adrenaline (A) and neuropeptide Y-like immunoreac-tivity (NPY-LI) were significantly increased as compared to healthy subjects ( P = 0.030, 0.046 and 0.001, respectively). The plasma level of the vasodilator substance P (SP-LI) was also higher in these patients ( P = 0.057 ).
These results indicate that in Bartter's syndrome the vasoconstrictive effect of catecholamines and angiotensin II may be enhanced by concomitant NPY release. Whether a release of the vasodilator substance P is an independent mechanism or represents a reflex response to the increased secretion of angiotensin II, catecholamines and/or NPY remains to be established. However, the significance of these biochemical findings for blood pressure maintenance in Bartter's syndrome remains to be settled.  相似文献   
39.
支气管镜介入在长期顽固性咯血患者治疗中的作用   总被引:3,自引:0,他引:3  
目的探讨支气管镜介入在长期顽固性咯血患者治疗中的作用.方法选择经内科药物止血、血管介入栓塞无效,又不能耐受外科手术的106例长期顽固性咯血患者,经采用支气管镜介入定位局部联合应用冷生理盐水(4℃左右)、1:10 000肾上腺素、凝血酶及Olympus PSD电刀电凝术等方法进行止血治疗.结果106例患者治愈58例(54.7%),有效41例(38.7%),无效7例(6.6%),总有效率达93.4%.结论经支气管镜介入局部定位联合应用冷盐水、肾上腺素、凝血酶及电刀电凝术治疗长期顽固性咯血疗效快、操作简便、安全可靠,值得临床推广应用.  相似文献   
40.
Summary Plasma testosterone, noradrenaline, and adrenaline concentrations during three bicycle ergometer tests of the same total work output (2160 J·kg–1) but different intensity and duration were measured in healthy male subjects. Tests A and B consisted of three consecutive exercise bouts, lasting 6 min each, of either increasing (1.5, 2.0, 2.5 W·kg–1) or constant (2.0, 2.0, 2.0 W·kg–1) work loads, respectively. In test C the subjects performed two exercise bouts each lasting 4.5 min, with work loads of 4.0 W·kg–1. All the exercise bouts were separated by 1-min periods of rest.Exercise B of constant low intensity resulted only in a small increase in plasma noradrenaline concentration. Exercise A of graded intensity caused an increase in both catecholamine levels, whereas, during the most intensive exercise C, significant elevations in plasma noradrenaline, adrenaline and testosterone concentrations occurred. A significant positive correlation was obtained between the mean value of plasma testosterone and that of adrenaline as well as noradrenaline during exercise.It is concluded that both plasma testosterone and catecholamine responses to physical effort depend more on work intensity than on work duration or total work output.This work was performed within the Scientific Exchange Programme between the Institute of Experimental Endocrinology, Slovak Academy of Sciences in Bratislava and Medical Research Centre, Polish Academy of Sciences, Warsaw/Project 10.4/  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