全文获取类型
收费全文 | 6883篇 |
免费 | 347篇 |
国内免费 | 409篇 |
学科分类
医药卫生 | 7639篇 |
出版年
2023年 | 31篇 |
2022年 | 63篇 |
2021年 | 106篇 |
2020年 | 112篇 |
2019年 | 104篇 |
2018年 | 93篇 |
2017年 | 113篇 |
2016年 | 148篇 |
2015年 | 135篇 |
2014年 | 295篇 |
2013年 | 430篇 |
2012年 | 265篇 |
2011年 | 316篇 |
2010年 | 287篇 |
2009年 | 281篇 |
2008年 | 347篇 |
2007年 | 376篇 |
2006年 | 324篇 |
2005年 | 333篇 |
2004年 | 318篇 |
2003年 | 289篇 |
2002年 | 243篇 |
2001年 | 234篇 |
2000年 | 175篇 |
1999年 | 167篇 |
1998年 | 172篇 |
1997年 | 150篇 |
1996年 | 120篇 |
1995年 | 136篇 |
1994年 | 122篇 |
1993年 | 90篇 |
1992年 | 84篇 |
1991年 | 102篇 |
1990年 | 92篇 |
1989年 | 75篇 |
1988年 | 74篇 |
1987年 | 81篇 |
1986年 | 52篇 |
1985年 | 75篇 |
1984年 | 104篇 |
1983年 | 49篇 |
1982年 | 72篇 |
1981年 | 75篇 |
1980年 | 71篇 |
1979年 | 53篇 |
1978年 | 44篇 |
1977年 | 35篇 |
1976年 | 45篇 |
1974年 | 22篇 |
1973年 | 15篇 |
排序方式: 共有7639条查询结果,搜索用时 15 毫秒
81.
S. V. Andreev I. D. Kobkova N. M. Bogdanova T. S. Kutyreva 《Bulletin of experimental biology and medicine》1978,86(2):1003-1006
To investigate the mechanisms of sudden death the authors determined the noradrenalin and adrenalin content in the myocardium of various parts of the heart by a fluorometric method; parallel determinations were made in the myocardium of persons dying accidentally. A heterotopic distribution of noradrenalin in the various parts of the heart after sudden death was found compared with its distribution after accidental death. Differences in the content of adrenalin and noradrenalin in the various parts of the heart of the two groups indicate that death was due to different mechanisms.Laboratory of Pathophysiology, Institute of Human Morphology, Academy of Medical Sciences of the USSR, Moscow (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 8, pp. 153–156, August, 1978. 相似文献
82.
目的探讨不同部位缺血预处理对未成熟心肌保护作用。方法采用经典心脏缺血预处理、肾缺血预处理及双下肢缺血预处理动物Langendorff灌注模型比较三种方法对缺血 /再灌(I/R)未成熟心肌损伤的效应。分为5组 :正常对照组(NC,n=6) ,离体心脏仅灌注KH液70min;缺血 /再灌 (I/R ,n=6) ,离体心脏灌注15min转为工作心15min后停灌45min,恢复灌注15min改为工作心30min;心脏缺血预处理组 (IPC,n=6),离体心脏灌注15min转为工作心15min后反复2次缺血5min/再灌5min,然后重复I/R组方法 ;肾缺血预处理组(K -IPC ,n=6) ,反复3次阻断左肾动脉5min,放开5min,然后重复I/R组方法。双下肢缺血预处理组 (DL-IPC ,n=6) ,反复3次捆扎双下肢5min,松开5min,然后重复I/R组方法。以左心室功能恢复、心肌含水量、血清肌酸激酶 (CK)和乳酸脱氢酶 (LDH)漏出率 ,心肌组织ATP和丙二醛 (MDA)含量、超氧化物歧化酶(SOD)活性及电镜作为观察指标。结果IPC、DL-IPC及K-IPC组在左心室功能恢复优于I/R组 (P<0.05) ,在ATP含量、SOD活性及心肌超微结构方面均优于I/R组(P<0.01) ,心肌含水量低于I/R组 (P<0.05) ,在MDA含量、CK、LDH漏出率方面均低于I/R组 (P<0.01)。结论不同部位的非心脏缺血预处理 ,与心脏缺血预处理可诱发同等的心肌保护作用 相似文献
83.
Domenico Lapenna Andrea Mezzetti Sergio de Gioia Agostino Consoli Davide Festi Carmine Di Ilio Franco Cuccurullo 《Pflügers Archiv : European journal of physiology》1994,427(5-6):432-436
The left ventricular subendocardial and subepicardial layers of six perfused rabbit hearts were tested for enzymatic and non-enzymatic antioxidant defences and for lipid peroxidation. The subendocardium showed significantly lower catalase activity and contents of non-protein thiol compounds and vitamin E associated with a higher degree of lipid peroxidation. The activities of Cu,Zn- and Mn-superoxide dismutases, glutathione reductase, -glutamylcysteine synthetase and -glutamyl transpeptidase showed no significant transmural differences, and Se-independent glutathione peroxidase activity was not detectable in either layer. Comparable results were observed in another group of six unperfused rabbit hearts. In five H2O2-perfused rabbit hearts, lipid peroxidation was higher, and myocardial creatine phosphokinase activity lower, in the subendocarium than in the subepicardium. In this group, only the subendocardium had significantly higher lipid peroxidation levels than the control hearts. Thus, a lower antioxidant capacity and a greater oxidative stress are present in the rabbit subendocardium. These findings could provide insight into the problem of subendocardial vulnerability to free radical-mediated processes, such as occurs in ischaemia-reperfusion injury. 相似文献
84.
目的:研究机械牵张对大鼠心肌蛋白激酶B(Akt)活化和心钠素(ANF)分泌的影响。方法:采用Langendorff方法灌流大鼠心脏,膨胀球囊持续牵张左心室,从左心室游离心肌,提取胞浆蛋白,用Western blot检测磷酸化Akt、总Akt水平;收集冠脉流出液,用放射免疫分析法检测冠脉流出液中ANF含量。结果:持续牵张不影响灌流心脏的心率和冠脉流出量。但经过20min持续牵张,牵张组心脏灌流液中ANF含量(209.89±65.45pg/ml)较对照组(108.84±25.18pg/ml)明显增高(P<0.01);牵张组大鼠左心室心肌组织磷酸化Akt水平(0.76±0.03)明显高于对照组(0.32±0.02),而总Akt水平与对照组相比无显著性差异。结论:机械牵张可引起心脏心钠素的分泌增加,其机制可能与胞内Akt信号通路的激活有关。 相似文献
85.
86.
S. Masumura M. Hashimoto Y. Hashimoto T. SatŌ I. Kihara Y. Watanabe 《European journal of applied physiology》1982,48(2):157-161
Summary Activities of glycolytic enzymes in the aorta were investigated in female Wistar rats. There were two groups of rats; one served as the control (sedentary rats), while the other group was forced to run on a treadmill for 10 weeks. In the control animals, the activities of hexokinase, phosphofructokinase and aldolase were relatively lower than those of the other glycolytic enzymes (phosphoglucose isomerase, lactate dehydrogenase and pyruvate kinase). After exercise, the activity of phosphofructokinase increased by 15%, whereas the other enzymatic activities were much the same as in the controls. Within the limits of the experiments, the increased percentage of phosphofructokinase was statistically significant (p<0.05). Since phosphofructokinase is a putative rate limiting enzyme, this enzymatic activation may indicate that glycolytic activity in the rat aorta is enhanced during and after running exercise. 相似文献
87.
Holger Warmuth Dr. Martin Fleischer Hermann Themann Richard-Siegfried Achatzy Herbert Dittrich 《Virchows Archiv : an international journal of pathology》1978,380(2):135-147
Zusammenfassung An den KammerwÄnden menschlicher linker Ventrikel, die auf Grund einer Aortenstenose, einer Aorteninsuffizienz oder eines kombinierten Aortenvitium hypertrophiert waren, wurden licht- und elektronenmikroskopisch morphometrische Untersuchungen angestellt. Die Ergebnisse wurden mit denen, die an nicht belasteten menschlichen linken Ventrikeln gewonnen wurden, verglichen.Lichtmikroskopisch unterscheiden sich die Anteile der Volumendichten des Interstitium und der Herzmuskelzellen am gesamten Herzmuskelgewebe nicht statistisch signifikant. Es konnte morphometrisch eine Zellvergrö\erung festgestellt werden, die aus der signifikanten Verringerung der Volumendichte der Zellkerne (P<0,001) und der Anzahl der Zellkerne pro TestflÄche (P<0,0001) gegenüber den beiden Normalkollektiven resultiert. Elektronenmikroskopisch ist eine Zunahme der Volumendichten der Myofibrillen (P<0,0001) auf Kosten des restlichen Cytoplasmas (P<0,001) festzustellen, wÄhrend die Volumendichte der Mitochondrien im Vergleich mit den jungen und alten Patienten abnahm (P<0,0001). Die OberflÄchendichte der Mitochondrien verringerte sich gegenüber den beiden Vergleichskollektiven (P<0,001) ebenso wie die der Cristae mitochondriales (P<0,0001). Diese Ergebnisse finden ihr morphologisches Korrelat in Mitochondriendestruktionen. Eine vermehrte Myolyse hat bei den hypertrophierten Herzen, die alle gewichtsmÄ\ig über dem kritischen Herzgewicht lagen, noch nicht eingesetzt. Bei allen Patienten wurde der herzchirurgische Eingriff mit Erfolg durchgeführt.
Ultrastructural morphometric analysis of hypertrophied human myocardial left ventricles
Summary Biopsies of hypertrophied human myocardial left ventricles were investigated morphometrically. The diagnoses of the patients were stenosis of the aortic valve, aortic insufficiency or a combination of both lesions. The results were compared with those from normally loaded human left ventricles.There are no differences on light microscopical level between the volume densities of interstitial tissue and of heart muscle cells in the three groups of patients. A significant diminution of the volume density of the nuclei (P<0.001) and the number of nuclei per test area (P<0.0001) when compared with normal groups suggests an increase in volume of the single heart muscle cell. The ultrastructural study shows marked increase in volume density of myofibrils (P<0.0001), with accompanying decrease in the volume densities of mitochondria (P<0.0001) and the remaining cytoplasm (P<0.001). A gross decrease in the surface area of mitochondria (P<0.001) and of cristae mitochondriales (P<0.0001) is found. The morphological equivalents of this result are numerous stages of mitochondrial destruction including cristolysis. All myocardial weights were beyond the critical heart weight.
Mit dankenswerter Unterstützung der Deutschen Forschungsgemeinschaft über den Sonderforschungsbereich SFB 104 相似文献
88.
V. Vihko J. SoimajÄrvi E. Karvinen P. Rahkila M. Havu 《European journal of applied physiology》1978,39(3):209-218
Summary On the basis of maximal oxygen uptake (
O2 max) 18 normal, healthy men were divided into two groups of equal size: moderately trained subjects (MTR) each having
O2 max below 65.0 ml·min–1·kg–1 body weight (54.0±8.3) and well trained subjects (WTR), whose
O2 max exceeded 65.0 ml·min–1·kg–1 body weight (69.2±4.1). The WTR group had slightly (non significant, n.s.) higher percentage of slow twitch, oxidative (SO) fibers in M. vastus lateralis and higher (n.s.) activities of cytochrome c oxidase (CytOx), succinate dehydrogenase (SDH), 3-hydroxyacyl-CoA-dehydrogenase (HADH), and citrate synthase (CS), while lactate dehydrogenase (LDH) activity was lower (n.s.). In the MTR group only, the SO-%, and the activities of CytOx, SDH and HADH correlated positively with
O2 max, and LDH negatively with
O2 max. These correlations were not significant in the WTR group possibly because of the adaptations produced by training in this group. Multiple regression analysis was used to elucidate the best combination of variables to explain the variance in
O2 max. The best model consisted of the sum of relative activities of oxidative muscle enzymes (CytOx, SDH, HADH, CS), muscle LDH activity, body fat content (% F) and lean body mass. This model explained 69% of the variance in
O2 max; and of the individual variables % F was of utmost importance. 相似文献
89.
Shklyar T. F. Rozenshtraukh L. V. Markhasin V. S. Savichevskii M. S. 《Bulletin of experimental biology and medicine》1984,98(4):1396-1400
Bulletin of Experimental Biology and Medicine - 相似文献
90.
目的:观察犬冠状动脉左旋支狭窄后心肌细胞对^99碍^m-甲氧基异丁基异腈(^99Tc^m-MIBI)摄取与时间变化之间的关系。方法:建立犬冠状动脉左旋支狭窄模型(12只),分别注射^99Tc^m-MIBI,剂量为185MBq(5mCi)。注射1h和4h后,各处死6只犬,取出心脏,于左室侧壁(缺血区)和前壁(正常区)分别取心肌组织约100rag,用1计数器测定其放射性计数,换算成每克组织放射性计数值,求出侧壁与前壁放射性比值。结果:注射后1h犬左心室缺血区与正常区组织放射性计数比值为0.726±O.054,4h为0.673±0.080,两者之间比较差鼻无昂薯件(t=1.3452.P〉0.05).结论.砸长时问不能摇高按血心肌对辨^99Tc^m-MIBI梧取比. 相似文献