全文获取类型
收费全文 | 745篇 |
免费 | 37篇 |
国内免费 | 4篇 |
专业分类
安全科学 | 42篇 |
废物处理 | 121篇 |
环保管理 | 120篇 |
综合类 | 109篇 |
基础理论 | 175篇 |
环境理论 | 4篇 |
污染及防治 | 122篇 |
评价与监测 | 36篇 |
社会与环境 | 44篇 |
灾害及防治 | 13篇 |
出版年
2023年 | 6篇 |
2022年 | 10篇 |
2021年 | 16篇 |
2020年 | 14篇 |
2019年 | 18篇 |
2018年 | 30篇 |
2017年 | 29篇 |
2016年 | 40篇 |
2015年 | 33篇 |
2014年 | 19篇 |
2013年 | 60篇 |
2012年 | 30篇 |
2011年 | 46篇 |
2010年 | 39篇 |
2009年 | 45篇 |
2008年 | 38篇 |
2007年 | 45篇 |
2006年 | 40篇 |
2005年 | 27篇 |
2004年 | 21篇 |
2003年 | 15篇 |
2002年 | 17篇 |
2001年 | 9篇 |
2000年 | 9篇 |
1999年 | 11篇 |
1998年 | 8篇 |
1997年 | 8篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1986年 | 6篇 |
1984年 | 2篇 |
1981年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1961年 | 3篇 |
1959年 | 2篇 |
1958年 | 2篇 |
1957年 | 5篇 |
1955年 | 5篇 |
1954年 | 2篇 |
1940年 | 2篇 |
1937年 | 1篇 |
1934年 | 1篇 |
1926年 | 1篇 |
排序方式: 共有786条查询结果,搜索用时 890 毫秒
521.
522.
523.
524.
Guillaume A. Schoch Marc Morant Nawroz Abdulrazzak Carole Asnaghi Simon Goepfert Maike Petersen Pascaline Ullmann Danièle Werck-Reichhart 《Environmental Chemistry Letters》2006,4(3):127-136
Together in silico and genetic mining approaches have recently designated the CYP98 family of plant cytochromes P450 as the family of enzymes that catalyzes the meta-hydroxylation step in the phenylpropanoid pathway. This meta-hydroxylation is not catalyzed on the free p-coumaric acid as anticipated, but on its conjugates with shikimic, quinic, or phenyllactic acids. While all CYP98s have in common phenol meta-hydroxylase activity, p-coumaroylshikimate remains their preferred substrate. High expression of CYP98s is detected in lignifying tissues in stems, roots, and siliques. The CYP98A3 gene disruption in Arabidopsis thaliana leads to a drastic inhibition of lignin synthesis, cell growth, and plant development. The meta-hydroxylation of phenolic precursors is thus essential for higher plant development. Isolation of coding sequences belonging to the CYP98 family from basil, wheat, and extensive functional analysis of the recombinant enzymes, together with CYP98s from other plant taxa, helps shedding some light on mechanisms of P450s evolution. Most importantly, the occurrence of the meta-hydroxylation on esters of shikimic or quinic acids introduces a new biochemical regulation mechanism in the phenylpropanoid pathway. 相似文献
525.
526.
527.
In running our increasingly complex business systems, formal risk analyses and risk management techniques are becoming more important part to managers: all managers, not just those charged with risk management. It is also becoming apparent that human behaviour is often a root or significant contributing cause of system failure. This latter observation is not novel; for more than 30 years it has been recognised that the role of human operations in safety critical systems is so important that they should be explicitly modelled as part of the risk assessment of plant operations. This has led to the development of a range of methods under the general heading of human reliability analysis (HRA) to account for the effects of human error in risk and reliability analysis. The modelling approaches used in HRA, however, tend to be focussed on easily describable sequential, generally low-level tasks, which are not the main source of systemic errors. Moreover, they focus on errors rather than the effects of all forms of human behaviour. In this paper we review and discuss HRA methodologies, arguing that there is a need for considerable further research and development before they meet the needs of modern risk and reliability analyses and are able to provide managers with the guidance they need to manage complex systems safely. We provide some suggestions for how work in this area should develop. But above all we seek to make the management community fully aware of assumptions implicit in human reliability analysis and its limitations. 相似文献
528.
G. Simon‐Sylvestre A. Beaumont 《Journal of environmental science and health. Part. B》2013,48(4):335-347
Abstract The results reported in this paper confirm the seasonal influence on soil nitrifying activity estimated in the laboratory. The variations of this activity depend on different factors: climatic conditions, soil nature, occurence of plants, characteristics of the organic matter added to the soil. A fresh organic matter (straw, for example) leads to reduced nitrifying activity immediately after its incorporation; its depressive action disappears after a month under laboratory condi‐tions. A decomposed organic matter, as a manure, produces no effect. This work also shows the seasonal variations of the mineral nitrogen immobilization after addition of a fresh organic matter. 相似文献
529.
Prenatal gene therapy aims to deliver genes to cells and tissues early in prenatal life, allowing correction of a genetic defect, before long-term tissue damage has occurred. In contrast to postnatal gene therapy, prenatal application can target genes to a large population of dividing stem cells, and the smaller fetal size allows a higher vector-to-target cell ratio to be achieved. Early-gestation delivery may allow the development of immune tolerance to the transgenic protein which would facilitate postnatal repeat vector administration if needed. Targeting particular organs will depend on manipulating the vector to achieve selective tropism and on choosing the most appropriate gestational age and injection method for fetal delivery. Intra-amniotic injection reaches the skin, and other organs that are bathed in the fluid however since gene transfer to the lung and gut is usually poor more direct injection methods will be needed. Delivery to the liver and blood can be achieved by systemic delivery via the umbilical vein or peritoneal cavity. Gene transfer to the central nervous system in the fetus is difficult but newer vectors are available that transduce neuronal tissue even after systemic delivery. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
530.