全文获取类型
收费全文 | 26198篇 |
免费 | 998篇 |
国内免费 | 234篇 |
学科分类
医药卫生 | 27430篇 |
出版年
2023年 | 169篇 |
2022年 | 427篇 |
2021年 | 605篇 |
2020年 | 485篇 |
2019年 | 414篇 |
2018年 | 482篇 |
2017年 | 643篇 |
2016年 | 728篇 |
2015年 | 616篇 |
2014年 | 1271篇 |
2013年 | 1415篇 |
2012年 | 1360篇 |
2011年 | 1525篇 |
2010年 | 1399篇 |
2009年 | 1409篇 |
2008年 | 1420篇 |
2007年 | 1352篇 |
2006年 | 1326篇 |
2005年 | 1181篇 |
2004年 | 903篇 |
2003年 | 809篇 |
2002年 | 601篇 |
2001年 | 643篇 |
2000年 | 561篇 |
1999年 | 497篇 |
1998年 | 447篇 |
1997年 | 448篇 |
1996年 | 380篇 |
1995年 | 381篇 |
1994年 | 334篇 |
1993年 | 254篇 |
1992年 | 272篇 |
1991年 | 225篇 |
1990年 | 217篇 |
1989年 | 154篇 |
1988年 | 156篇 |
1987年 | 180篇 |
1986年 | 143篇 |
1985年 | 171篇 |
1984年 | 165篇 |
1983年 | 105篇 |
1982年 | 131篇 |
1981年 | 114篇 |
1980年 | 114篇 |
1979年 | 116篇 |
1978年 | 93篇 |
1977年 | 104篇 |
1976年 | 94篇 |
1975年 | 79篇 |
1973年 | 84篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Alessia Pascale Marialaura Amadio Stefano Govoni Fiorenzo Battaini 《Pharmacological research》2007,55(6):560-569
The brain represents the primary centre for the regulation and control of all our body activities, receiving and interpreting sensory impulses and transmitting information to the periphery. Most importantly, it is also the seat of consciousness, thought, emotion and especially memory, being in fact able to encode, store and recall any information. Memory is really what makes possible so many of our complex cognitive functions, including communication and learning, and surely without memory, life would lose all of its glamour and purpose. Age-associated mental impairment can range in severity from forgetfulness at the border with pathology to dementia, such as in Alzheimer's disease. In recent years, one of the most relevant observations of research on brain aging relates to data indicating that age-related cognitive decline is not only due to neuronal loss, as previously thought; instead, scientists now believe that age-associated functional changes have more to do with the dysfunctions occurring over time. Within this context a prominent role is certainly played by signal transduction cascades which guarantee neuronal cell to elaborate coordinated responses to the multiple signals coming from the outside and to adapt itself to the environmental changes and requests. This review will focus the attention on protein kinase C pathway, with a particular interest on its activation process, and on the role of protein-lipid and protein-protein interactions to selectively localize the cellular responses. Furthermore, information is emerging and will be discussed on the possibility of mRNA stabilization through PKC activation. This review will also approach the issue on how alterations of these molecular cascades may have implications in physiological and pathological brain aging, such as Alzheimer's disease. 相似文献
13.
Pathophysiological aspects of brain edema 总被引:16,自引:0,他引:16
Igor Klatzo 《Acta neuropathologica》1987,72(3):236-239
Summary Two mayor types of brain edema, related to two different pathomechanisms, can be recognized: 1)cytotoxic type-where the main feature is the swelling of cellular elements of brain parenchyma and 2)vasogenic type-where an increased vascular permeability leading to accumulation of edema fluid inthe extracellular spaces plays the principal role. In this type of edema, there is a close interrelationship between extravasation of serum proteins and retention of water in the brain tissue. In theischemic brain edema both cytotoxic and vasogenic mechanisms are involved. A biphasic opening of the blood-brain barrier, associated with vasogenic edema, is observed following release of major cerebral artery occlusion. The first opening of the barrier is related to a reactive hyperemia which follows promptly recirculation. The second opening, recognizable after a delay, is associated with a severe ischemic brain tissue injury.Dedicated to Prof. F. Seitelberger on the occasion of his seventieth birthday 相似文献
14.
Summary Cranial computed tomography (CT) of 108 cases with dilated lateral ventricles was reviewed to elucidate the relationship between focal vulnerability of developing brain and disproportional dilatation of lateral ventricles. CT findings of 108 cases with symmetrical dilatation of lateral ventricles were classified into three types by morphometry of lateral ventricles: anterior horn predominant type (31 cases), diffuse type (36 cases), posterior horn predominant type (41 cases). Posterior horn predominant type has a tendency to occur in congenital anomalies and premature brain damage, and anterior horn predominant type in infantile brain damage. This disproportional dilatation of anterior or posterior horns suggests a vulnerability of periventricular structure in developing brain. 相似文献
15.
16.
17.
Understanding the mechanisms of food intake and obesity 总被引:2,自引:1,他引:1
E. T. Rolls 《Obesity reviews》2007,8(S1):67-72
18.
Using the whole-cell configuration of the patch clamp technique, calcium-activated potassium currents (IK,Ca) were investigated in ramified murine brain macrophages. In order to induce IK,Ca the intracellular concentration of nominal free Ca2+ was adjusted to 1μM. The Ca2+-activated K+ current of brain macrophages did not show any voltage dependence at test potentials between –120 and +30mV. A tenfold change
in extracellular K+ concentration shifted the reversal potential of IK,Ca by 51mV. The bee venom toxin apamin applied at concentrations of up to 1μM did not affect IK,Ca. Ca2+-activated K+ currents of ramified brain macrophages were highly sensitive to extracellularly applied charybdotoxin (CTX). The half-maximal
effective concentration of CTX was calculated to be 4.3nM. In contrast to CTX, the scorpion toxin kaliotoxin did not inhibit
IK,Ca at concentrations between 1 and 50nM. Tetraethylammonium (TEA) blocked 8.0% of IK,Ca at a concentration of 1mM, whereas 31.4% of current was blocked by 10mM TEA. Several inorganic polyvalent cations were tested
at a concentration of 2mM for their ability to block IK,Ca. La3+ reduced IK,Ca by 72.8%, whereas Cd2+ decreased IK,Ca by 17.4%; in contrast, Ni2+ did not have any effect on IK,Ca. Ba2+ applied at a concentration of 1mM reduced IK,Ca voltage-dependently at hyperpolarizing potentials.
Received: 17 January / Accepted: 5 May 1997 相似文献
19.
20.
I. Hilakivi L. Ahtee J. O. Rinne T. Taira L. M. J. Attila P. Marjamäki 《Journal of neural transmission (Vienna, Austria : 1996)》1995,102(2):139-148
Summary Rats were treated with desipramine 5mg/kg, nomifensine 10mg/kg, zimelidine 25 mg/kg or with 0.9% sodium chloride once a day during the second and third weeks after birth, and brain stem, caudate/putamen and cortical monoamines, and caudate/putamen dopamine D1 (3[H]SCH 23390) and D2 (3[H]spiroperidol) receptor binding were measured when rats were at two months of age. In the brain stem, the concentration of 3-methoxy-4-hydroxy-phenyl glycol was increased in nomifensine rats and the ratio of 5-hydroxyindoleacetic acid to 5-hydroxytryptamine was increased in zimelidine rats. In the caudate/putamen, the concentrations of 3,4-dihydroxyphenylacetic acid and homovanillic acid and the ratio of homovanillic acid to dopamine were increased in desipramine rats; neither3[H]SCH 23390 nor3[H]spiroperidol binding were affected by any of the three monoamine uptake inhibiting antidepressants studied. In the cortex, the ratio of 5-hydroxyindoleacetic acid to 5-hydroxytryptamine was increased in desipramine and zimelidine rats. The findings suggest that desipramine but not nomifensine increases the metabolism of dopamine in the caudate/ putamen and nomifensine but not desipramine increases the metabolism of norepinephrine in the brain stem, and furthermore that the metabolism of serotonin is affected by desipramine as well as by zimelidine. It is possible that also treatment of women with these drugs during late pregnancy causes long-lasting changes in the brain of human fetus. 相似文献