全文获取类型
收费全文 | 4706篇 |
免费 | 286篇 |
国内免费 | 75篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 156篇 |
妇产科学 | 15篇 |
基础医学 | 371篇 |
口腔科学 | 2篇 |
临床医学 | 725篇 |
内科学 | 1662篇 |
皮肤病学 | 3篇 |
神经病学 | 450篇 |
特种医学 | 248篇 |
外科学 | 586篇 |
综合类 | 521篇 |
预防医学 | 57篇 |
眼科学 | 4篇 |
药学 | 184篇 |
1篇 | |
中国医学 | 32篇 |
肿瘤学 | 42篇 |
出版年
2023年 | 94篇 |
2022年 | 124篇 |
2021年 | 210篇 |
2020年 | 209篇 |
2019年 | 245篇 |
2018年 | 200篇 |
2017年 | 130篇 |
2016年 | 99篇 |
2015年 | 127篇 |
2014年 | 266篇 |
2013年 | 229篇 |
2012年 | 176篇 |
2011年 | 225篇 |
2010年 | 176篇 |
2009年 | 208篇 |
2008年 | 240篇 |
2007年 | 244篇 |
2006年 | 209篇 |
2005年 | 190篇 |
2004年 | 134篇 |
2003年 | 137篇 |
2002年 | 84篇 |
2001年 | 92篇 |
2000年 | 62篇 |
1999年 | 73篇 |
1998年 | 53篇 |
1997年 | 95篇 |
1996年 | 55篇 |
1995年 | 65篇 |
1994年 | 55篇 |
1993年 | 45篇 |
1992年 | 49篇 |
1991年 | 58篇 |
1990年 | 45篇 |
1989年 | 31篇 |
1988年 | 29篇 |
1987年 | 34篇 |
1986年 | 39篇 |
1985年 | 33篇 |
1984年 | 32篇 |
1983年 | 22篇 |
1982年 | 25篇 |
1981年 | 25篇 |
1980年 | 13篇 |
1979年 | 18篇 |
1978年 | 15篇 |
1977年 | 13篇 |
1976年 | 16篇 |
1974年 | 6篇 |
1973年 | 8篇 |
排序方式: 共有5067条查询结果,搜索用时 15 毫秒
51.
Hikaru Matsuda Yoshiyuki Taenaka Nobukazu Ohkubo Masakatu Ohtani Kyouichi Nishigaki Shigeaki Ohtake Takuya Miura Nobuyuki Taenaka† Hisateru Takano Hajime Hirose Yasunaru Kawashima 《Artificial organs》1988,12(5):423-430
Pneumatic ventricular assist device (VAD) was utilized for cardiogenic shock after intracardiac operation in two children with complex cardiac anomalies based with single ventricle. In the first case (a 10-year-old), after a modified Fontan operation, VAD was placed between the functional left atrium and ascending aorta, serving as a "artificial single ventricle" with neither pumping chamber nor artificial support in the right side of the heart. The systemic circulation was maintained by keeping relatively high central venous pressure. In another child (a 3-year-old) who underwent repair of incompetent atrioventricular valve leaving intracardiac lesions, VAD was placed between the common atrium and ascending aorta, serving as a pump for both pulmonary and systemic circulation with regulation of pulmonary blood flow through an aortopulmonary Gore-Tex shunt. The circulatory assist with VAD was utilized for 5 and 6 days, respectively. Although weaning from the device was not feasible in both patients because of the pulmonary dysfunction, these experience showed the possible use of VAD for cardiogenic shock after surgery in patients with complex cardiac anomalies. 相似文献
52.
Cannabinoids have been shown to influence food intake, and until recently, the neural pathways mediating these effects have remained obscure. It has been previously shown that intracerebroventricular injection of delta-9-tetrahydrocannabinol (Δ9-THC) causes increased consumption of palatable foods in rats, and we postulated the involvement of the hindbrain in this cannabinoid-induced food intake. Cannulated rats (both female and male groups) trained to consume sweetened condensed milk received either lateral or fourth ventricle injections of CP 55,940 and were presented with sweetened condensed milk 15 min after injection. Rats were injected over a range of doses between 100 pg and 10 μg per rat. Milk intake was recorded for a total of 3 h. Lateral ventricle injection of CP 55,940 increased milk intake at doses in the microgram range. However, CP 55,940 was effective in increasing food intake at nanogram doses when injected into the fourth ventricle. Finally, male rats appeared to be more sensitive to CP 55,940 than female rats inasmuch as milk consumption was increased at the 1 ng dose in male rats, whereas only the 10 ng dose was effective in females. These results indicate that CP 55,940 may act in the hindbrain to influence feeding behavior in rats. 相似文献
53.
S. Haruyama H. Mori L. M. Wan Y. Shinozaki H. Sakamoto H. Okino 《Medical & biological engineering & computing》1994,32(Z1):S91-S98
We proposed a mathematical model to describe the early filling process of the left ventricle and applied the model toin vivo experiments. The solution of a second-order differential equation indicated that the pressure difference between the left
atrium and ventricle during ventricular filling (PD) could be explained by a transient response, i.e. decremental oscillation,
in an LCR circuit. Thereafter, we analysed the sequence of PD during vagal stimulation with two catheter-tip manometers in
12 anaesthetised dogs and evaluated changes in the parameters of the system under various haemodynamic conditions. The values
of ωn and ξ were quite stable among beats within an episode of vagal stimulation, between episodes and even among dogs, despite
the changes in haemodynamic variables. Pericardiotomy and partial discommunication of the mitral valve with the left ventricular
free wall by cutting the mitral chordal tendons decreased ωn and increased ζ, mainly because of the increase in CLV. Occlusion of the coronary vascular beds with large numbers of microspheres increased ωn and decreased ζ, mainly because of the decrease in CLV. Mitral obstruction with an inflated balloon (increase in R) abolished the oscillatory changes and produced and exponential
decay sequence of PD. In conclusion, both the logical and experimental approaches indicated that the sequence of PD could
be considered as decremental oscillation in the LCR circuit and the parameters ωn and ξ could be good indices of the diastolic property of the left ventricle 相似文献
54.
内窥镜下第三脑室手术的应用解剖 总被引:1,自引:4,他引:1
目的 :为神经内窥镜下进行第三脑室手术提供解剖学资料。方法 :对 2 1例成人尸头固定标本进行第三脑室的解剖观察和测量 ,对 9具新鲜尸头进行经室间孔入路神经内窥镜下第三脑室的解剖学观察。结果 :室间孔长径、宽径为 (5 .4± 1.2 )mm、(2 .7± 0 .9)mm ,中间块长径、宽径为 (6.8± 2 .3 )mm、(3 .8± 1.0 )mm ,前后联合间距 (2 1.8± 2 .1)mm ,前、后联合到中间块为 (6.3± 0 .8)mm、(8.8± 1.3 )mm ,前后联合中点处第三脑室高度 (13 .8± 1.4)mm ,室间孔下、后联合前及中间块上、下第三脑室宽度分别为 (6.3±2 .2 )mm、(4 .9± 1.8)mm、(3 .4± 1.6)mm和 (4 .3± 1.8)mm ,中间块上、下最小高度为 (4 .4± 1.3 )mm和(4 .3± 1.3 )mm。内窥镜可较清晰显示第三脑室内结构 ,但中间块可影响显露。结论 :内窥镜下经室间孔入路进行第三脑室手术有一个理想的操作空间。 相似文献
55.
56.
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
57.
The effects, on operant feeding, of injection into the lateral cerebral ventricle of 50 μmoles CaCl2, 4 mmoles D-glucose, 2-deoxy-D-glucose (2DG) or xylose, or NaCl, have been studied in five pigs. All the sugars and CaCl2 were given in 1 ml of normal saline. Each of the sugar solutions produced transient drinking. Only CaCl2 and 2DG significantly increased food intake during the hour following injection. The results show that the mechanism by which the pig responds to intracerebroventricular 2DG is similar to that of the rat and different from that of the sheep. 相似文献
58.
Although little is known about the neuroanatomical basis of skin conductance orienting in intact normal humans, the limited literature on animals and humans with neurological and clinical disorders implicate prefrontal, temporal/amygdala, and pons brain areas in mediating skin conductance orienting. This study relates area of these structures using magnetic resonance imaging techniques to skin conductance orienting responses in 17 normal humans in order to test hypotheses that larger area of these excitatory structures will be associated with more orienting responses. Left and right hand skin conductance orienting was significantly associated with left and right prefrontal area (r = .44-.60), area of the pons (r = .43-.54), and left but not right temporal/amygdala area (r = .47-.53). No relationships were observed with areas thought to be unrelated to skin conductance activity (cerebellum, nonfrontal cortical area), medial prefrontal cortex, or the third ventricle. This appears to be the first study relating brain structure to skin conductance orienting in intact normal humans. Although preliminary at the present time, these results implicate prefrontal, pons, and temporal/amygdala areas in the mediation of skin conductance orienting in normal humans. 相似文献
59.
犬21只,经左冠脉内注射麦角新硷诱发冠脉痉挛后随机静滴生理盐水(对照组)或等量盐水溶的巯甲丙脯酸(治疗组),观察1小时。心电图显示治疗组的异常ST段下降和严重室性心律失常明显少于对照组;冠脉造影显示治疗组痉挛血管支数及狭窄程度均少于和轻于对照组;左室造影和超声心电图显示治疗组的左室收缩末和舒张末容积小于对照组,EF值或△D大于对照组,AA/EA小于对照组;血流动力学参数表明治疗组左室收缩压,平均肺 相似文献
60.
S E Harding G Vescovo S M Jones G Bennett M Yacoub P A Poole-Wilson 《The Journal of pathology》1989,159(3):191-196
Isolated single myocytes were prepared from myocardium of developing ventricular aneurysms and from myocardium within the scar of chronic ventricular aneurysms. The morphology and function of the individual cells were compared. The cells from developing aneurysms were rod-shaped, with a distinct sarcomeric structure, but did not contract even in the presence of high calcium concentrations. The sarcomere length was significantly higher than that of cells from chronic aneurysms and approached the theoretical point at which no contraction can occur. Cells from chronic aneurysms were either rod-shaped and contractile, or rounded due to hypercontracture of the myofilaments. Electron microscopy of cells from developing aneurysms confirmed the presence of elongated sarcomeres, a loss of the actin-myosin interdigitation, and damage to the contractile proteins which was particularly evident in the thin filaments. Cells with similar characteristics have also been isolated from a ruptured, ischaemic papillary muscle. These changes, which are due either to ischaemia or to overstretching of cells, may account for the weakness of the wall of developing aneurysms and be a cause of rupture or enlargement. 相似文献