全文获取类型
收费全文 | 556篇 |
免费 | 33篇 |
国内免费 | 2篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 12篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 15篇 |
2017年 | 8篇 |
2016年 | 18篇 |
2015年 | 35篇 |
2014年 | 33篇 |
2013年 | 51篇 |
2012年 | 45篇 |
2011年 | 37篇 |
2010年 | 20篇 |
2009年 | 23篇 |
2008年 | 39篇 |
2007年 | 30篇 |
2006年 | 23篇 |
2005年 | 23篇 |
2004年 | 20篇 |
2003年 | 22篇 |
2002年 | 21篇 |
2001年 | 5篇 |
2000年 | 2篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1989年 | 10篇 |
1988年 | 3篇 |
1986年 | 6篇 |
1985年 | 2篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1968年 | 1篇 |
1966年 | 2篇 |
1964年 | 1篇 |
1951年 | 1篇 |
1930年 | 1篇 |
排序方式: 共有591条查询结果,搜索用时 93 毫秒
1.
Murilo S. Baptista Rero M. Rubinger Emilson R. Viana José C. Sartorelli Ulrich Parlitz Celso Grebogi 《PloS one》2012,7(10)
The amount of information exchanged per unit of time between two nodes in a dynamical network or between two data sets is a powerful concept for analysing complex systems. This quantity, known as the mutual information rate (MIR), is calculated from the mutual information, which is rigorously defined only for random systems. Moreover, the definition of mutual information is based on probabilities of significant events. This work offers a simple alternative way to calculate the MIR in dynamical (deterministic) networks or between two time series (not fully deterministic), and to calculate its upper and lower bounds without having to calculate probabilities, but rather in terms of well known and well defined quantities in dynamical systems. As possible applications of our bounds, we study the relationship between synchronisation and the exchange of information in a system of two coupled maps and in experimental networks of coupled oscillators. 相似文献
2.
Establishment of a new conditionally immortalized human skeletal muscle microvascular endothelial cell line 下载免费PDF全文
3.
Systematic Parasitology - Bicentenariella n. g. is proposed to accommodate three new species of dactylogyrid monogeneans found on the gills of the threadfin bass Pronotogrammus multifasciatus Gill... 相似文献
4.
Fabiana K. Ludka Tharine Dal-Cim Luisa Bandeira Binder Leandra Celso Constantino Caio Massari Carla I. Tasca 《Molecular neurobiology》2017,54(5):3149-3161
Atorvastatin has been shown to exert a neuroprotective action by counteracting glutamatergic toxicity. Recently, we have shown atorvastatin also exerts an antidepressant-like effect that depends on both glutamatergic and serotonergic systems modulation. Excitotoxicity is involved in several brain disorders including depression; thus, it is suggested that antidepressants may target glutamatergic system as a final common pathway. In this study, a comparison of the mechanisms involved in the putative neuroprotective effect of a repetitive atorvastatin or fluoxetine treatment against glutamate toxicity in hippocampal slices was performed. Adult Swiss mice were treated with atorvastatin (10 mg/kg, p.o.) or fluoxetine (10 mg/kg, p.o.), once a day during seven consecutive days. On the eighth day, animals were killed and hippocampal slices were obtained and subjected to an in vitro protocol of glutamate toxicity. An acute treatment of atorvastatin or fluoxetine was not neuroprotective; however, the repeated atorvastatin or fluoxetine treatment prevented the decrease in cellular viability induced by glutamate in hippocampal slices. The loss of cellular viability induced by glutamate was accompanied by increased D-aspartate release, increased reactive oxygen species (ROS) and nitric oxide (NO) production, and impaired mitochondrial membrane potential. Atorvastatin or fluoxetine repeated treatment also presented an antidepressant-like effect in the tail suspension test. Atorvastatin or fluoxetine treatment was effective in protecting mice hippocampal slices from glutamate toxicity by preventing the oxidative stress and mitochondrial dysfunction. 相似文献
5.
Alexandra Becerra Celso Quintero Valeria Morales Mauricio Valderrama Adam Aguirre Mario A. Faúndez Rene S. Rojas 《Bioorganic & medicinal chemistry》2017,25(10):2681-2688
We synthesized a new family of six 4(3H)quinazolinimines based on the reaction between (E)-N-(2-cyanophenyl)benzimidoyl chloride and substituted anilines reaching the formation of their corresponding C2, N3-substituted quinazoliniminium chlorides. This method provides novel, direct and flexible access to diverse substituted 4(3H)quinazolinimines.New compounds obtained following the proposed synthesis were fully characterized and, including the thirteen 4(3H)quinazolinimines synthesized by this method and previously reported by us, were used to study its cytotoxic effect on neoplastic cell lines. The mechanism involved in cell toxicity was also studied. Results showed that these compounds were highly cytotoxic, in particular on Human Promyelocytic Leukemia cells (HL60) and Chronic Myelogenous Leukemia cells (K562) when compared with conventional antineoplastic drugs such as etoposide and cisplatin. The mechanism associated to cytotoxic effect was mainly apoptosis, which not was decreased by antioxidant addition, thereby suggesting that the compounds exert apoptotic death through a mechanism unrelated with oxidative stress. 相似文献
6.
7.
8.
Vanadate (+5) is a potent inhibitor of a variety of ATPases including dynein ATPase. We describe a method useful for estimating the functional dissociation rate of vanadate from the active site which does not rely on classical physical separation techniques. The method involves spectrophotometrically monitoring the enzymatic activity as the inhibitor dissociates from the enzyme and is inactivated by norepinephrine. Norepinephrine effectively reverses vanadate inhibition by reducing vanadate (+5) to oxovanadium (+4). This reduction by norepinephrine is sufficiently fast for these purposes--addition of vanadate after norepinephrine shows no inhibition of ATPase activity. The mathematical estimation procedure is generally useful for estimation of dissociation rates of other reversible inhibitors which can be quickly inactivated after dissociation from the enzyme. The rate of dissociation of vanadate from dynein with ATP and 2-N3ATP as substrates using this method was estimated to be in the ranges 0.0023-0.0042 and 0.0057-0.0075 s-1, respectively. These rates permit estimation of the rates of vanadate association with dynein by using the reported dissociation constant for vanadate. The results are consistent with the very fast and potent inhibition of dynein ATPase activity observed. 相似文献
9.
10.