全文获取类型
收费全文 | 808篇 |
免费 | 58篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 10篇 |
2020年 | 11篇 |
2019年 | 8篇 |
2018年 | 14篇 |
2017年 | 18篇 |
2016年 | 25篇 |
2015年 | 36篇 |
2014年 | 42篇 |
2013年 | 66篇 |
2012年 | 40篇 |
2011年 | 71篇 |
2010年 | 54篇 |
2009年 | 37篇 |
2008年 | 39篇 |
2007年 | 38篇 |
2006年 | 39篇 |
2005年 | 39篇 |
2004年 | 37篇 |
2003年 | 37篇 |
2002年 | 37篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 9篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1979年 | 4篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 9篇 |
1973年 | 3篇 |
1969年 | 1篇 |
排序方式: 共有866条查询结果,搜索用时 453 毫秒
71.
Dragisic C Ashkenazi E Bede L Honzák M Killeen T Paglia A Semroc B Savy C 《Journal of industrial microbiology & biotechnology》2011,38(2):371-374
Increasingly, government regulations, voluntary standards, and company guidelines require that biofuel production complies with sustainability criteria. For some stakeholders, however, compliance with these criteria may seem complex, costly, or unfeasible. What exiting tools, then, might facilitate compliance with a variety of biofuel-related sustainability criteria? This paper presents four existing tools and methodologies that can help stakeholders assess (and mitigate) potential risks associated with feedstock production, and can thus facilitate compliance with requirements under different requirement systems. These include the Integrated Biodiversity Assessment Tool (IBAT), the ARtificial Intelligence for Ecosystem Services (ARIES) tool, the Responsible Cultivation Areas (RCA) methodology, and the related Biofuels + Forest Carbon (Biofuel + FC) methodology. 相似文献
72.
73.
74.
75.
Giordano G Sánchez-Pérez AM Montoliu C Berezney R Malyavantham K Costa LG Calvete JJ Felipo V 《Journal of neurochemistry》2005,94(3):808-818
Activation of NMDA receptors leads to activation of cAMP-dependent protein kinase (PKA). The main substrates phosphorylated by PKA following NMDA receptor activation remain unidentified. The aim of this work was to identify a major substrate phosphorylated by PKA following NMDA receptor activation in cerebellar neurones in culture, and to assess whether this phosphorylation may be involved in neuronal death induced by excessive NMDA receptor activation. The main PKA substrate following NMDA receptor activation was identified by MALDI-TOFF fingerprinting as the nuclear protein, matrin 3. PKA-mediated phosphorylation of matrin 3 is followed by its degradation. NMDA receptor activation in rat brain in vivo by ammonia injection also induced PKA-mediated matrin 3 phosphorylation and degradation in brain cell nuclei. Blocking NMDA receptors in brain in vivo with MK-801 reduced basal phosphorylation of matrin 3, suggesting that it is modulated by NMDA receptors. Inhibition of PKA with H-89 prevents NMDA-induced phosphorylation and degradation of matrin 3 as well as neuronal death. These results suggest that PKA-mediated phosphorylation of matrin 3 may serve as a rapid way of transferring information from synapses containing NMDA receptors to neuronal nuclei under physiological conditions, and may contribute to neuronal death under pathological conditions. 相似文献
76.
Giordano G Sanchez-Perez AM Burgal M Montoliu C Costa LG Felipo V 《Journal of neurochemistry》2005,92(1):143-157
Hyperammonemia is responsible for most neurological alterations in patients with hepatic encephalopathy by mechanisms that remain unclear. Hyperammonemia alters phosphorylation of neuronal protein kinase C (PKC) substrates and impairs NMDA receptor-associated signal transduction. The aim of this work was to analyse the effects of hyperammonemia on the amount and intracellular distribution of PKC isoforms and on translocation of each isoform induced by NMDA receptor activation in cerebellar neurons. Chronic hyperammonemia alters differentially the intracellular distribution of PKC isoforms. The amount of all isoforms (except PKC zeta) was reduced (17-50%) in the particulate fraction. The contents of alpha, beta1, and epsilon isoforms decreased similarly in cytosol (65-78%) and membranes (66-83%), whereas gamma, delta, and theta; isoforms increased in cytosol but decreased in membranes, and zeta isoform increased in membranes and decreased in cytosol. Chronic hyperammonemia also affects differentially NMDA-induced translocation of PKC isoforms. NMDA-induced translocation of PKC alpha and beta is prevented by ammonia, whereas PKC gamma, delta, epsilon, or theta; translocation is not affected. Inhibition of phospholipase C did not affect PKC alpha translocation but reduced significantly PKC gamma translocation, indicating that NMDA-induced translocation of PKC alpha is mediated by Ca2+, whereas PKC gamma translocation is mediated by diacylglycerol. Chronic hyperammonemia reduces Ca+2-mediated but not diacylglycerol-mediated translocation of PKC isoforms induced by NMDA. 相似文献
77.
X-ray crystallographic studies performed on the product of the ketalization reaction of 13beta-ethyl-11alpha-hydroxy-gon-5-ene-3,17-dione have lead to the unequivocal assignment of the 10alpha stereochemistry to C10, showing that an inversion of configuration occurred during formation of the 3,17-diketal. From the Swern oxidation of this compound, 11alpha-(methylthio)methoxy-10alpha-gonene was obtained as the major product instead of the desired 11-ketone. Modeling studies showed that the configurational instability at C10 is determined by the presence of the 11alpha-hydroxyl group. 相似文献
78.
79.
Rizzi E Dallavalle S Merlini L Beretta GL Pratesi G Zunino F 《Bioorganic & medicinal chemistry letters》2005,15(19):4313-4316
A new synthesis of isoaurones related to the alleged structure of isoaurostatin, via Heck intramolecular cyclization of cinnamic esters of 2-iodophenols, is reported. The cytotoxic activity of these isoaurones is lower than that of the structurally very similar 4-arylcoumarins. 相似文献
80.
NTP-CERHR Expert Panel Report on the reproductive and developmental toxicity of methylphenidate 总被引:1,自引:0,他引:1