全文获取类型
收费全文 | 723篇 |
免费 | 2篇 |
国内免费 | 9篇 |
专业分类
安全科学 | 12篇 |
废物处理 | 11篇 |
环保管理 | 63篇 |
综合类 | 159篇 |
基础理论 | 131篇 |
环境理论 | 2篇 |
污染及防治 | 264篇 |
评价与监测 | 52篇 |
社会与环境 | 39篇 |
灾害及防治 | 1篇 |
出版年
2023年 | 6篇 |
2022年 | 18篇 |
2021年 | 10篇 |
2020年 | 9篇 |
2019年 | 8篇 |
2018年 | 23篇 |
2017年 | 16篇 |
2016年 | 49篇 |
2015年 | 31篇 |
2014年 | 45篇 |
2013年 | 55篇 |
2012年 | 46篇 |
2011年 | 55篇 |
2010年 | 24篇 |
2009年 | 27篇 |
2008年 | 47篇 |
2007年 | 43篇 |
2006年 | 34篇 |
2005年 | 27篇 |
2004年 | 34篇 |
2003年 | 25篇 |
2002年 | 19篇 |
2001年 | 12篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 1篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1968年 | 1篇 |
1961年 | 1篇 |
1952年 | 1篇 |
1921年 | 1篇 |
排序方式: 共有734条查询结果,搜索用时 0 毫秒
481.
482.
483.
484.
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
485.
The present prospective study examines the interplay between the quality of relationships with coworkers and work motivation in predicting burnout. Considering self-determined motivation at work as a potential moderator, we investigated whether relationships with coworkers are equally important to all employees in preventing burnout. A total of 533 college employees participated in this study. Data were collected at two time points, two years apart. Results from structural equation modeling indicated negative main effects for high-quality relationships and self-determined motivation on burnout. A significant interaction effect between these two factors on burnout was also revealed, suggesting that high-quality relationships with coworkers is crucial for those employees who exhibit less self-determined work motivation. Implications for burnout research and management practices are discussed (Deci & Ryan, 1985 ). Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
486.
Sigurd Rognerud Vladimir A. Dauvalter Eirik Fjeld Brit Lisa Skjelkvåle Guttorm Christensen Nickolay Kashulin 《Ambio》2013,42(6):724-736
A large copper–nickel smelter complex is located at the Kole Penninsula, Russia, close to the Norwegian border. Trace-element concentrations in surface sediments (0–0.5 cm) and pre-industrial sediments from 45 lakes in the region were used to uncover spatial deposition patterns and contamination factor of sediments. Elevated concentrations were found, especially for Ni and Cu, but also for Pb, Co, Hg, As, and Cd. Highest concentrations were found up to 20 km from the smelter, but the concentrations decreased exponentially with distance from the smelter. Increasing Ni, Cu, As, and Hg concentrations from sub-surface to surface sediments were found for lakes at intermediate distances (20–60 km). This may reflect recent changes in atmospheric depositions, as shown in nearby Norwegian areas. However, we cannot rule out that this also may have been caused by diagenetic processes, especially for the most redox-sensitive elements such as As. 相似文献
487.
Patience U. Ajonina Gordon N. Ajonina Emmanuel Jin Fidèle Mekongo Isidore Ayissi Leonard Usongo 《国际发展与全球生态学杂志》2013,20(2):161-172
Socio-economic surveys were carried out in the Malimba and Mouanko communities in the Sanaga delta region of the Douala-Edea Wildlife Reserve, Cameroon, on the exploitation, processing and marketing of bivalves, with emphasis on gender aspects and impacts on the surrounding forest resources. Sixty people from 16 villages were sampled using a structured questionnaire with field observations documented during the peak fishing period (November 2000–June 2001). Results indicated a strong gender differentiation in the activity, with males dominating bivalve harvesting and shell processing and women dominating the processing for meat. Monthly bivalve meat production of 32.9 tons (197.4 tons per year) generated revenues of 65.4 million FCFA (74.9 million per year). Monthly shell production was put at 1380 tons (8040 tons per year) generating a monthly revenue of 74 million FCFA (444 million per year). Problems faced during exploitation, processing and marketing stages include physical, health and socio-economic: use of very depreciable rudimentary tools, shell injuries, fire and hot water burns, insect pests; blindness, deafness; inadequate storage facilities, transport and remoteness of the area. Bivalve processing activities using wood contributed to a total annual harvest of 50 986 m3 from the surrounding forest. Sustainable conservation measures geared towards poverty alleviation are proposed. 相似文献
488.
Corinne Lampin-Maillet Marielle Jappiot Marlène Long Christophe Bouillon Denis Morge Jean-Paul Ferrier 《Journal of environmental management》2010,91(3):732-741
Every year, more than 50,000 wildland fires affect about 500,000 ha of vegetation in southern European countries, particularly in wildland-urban interfaces (WUI). This paper presents a method to characterize and map WUIs at large scales and over large areas for wildland fire prevention in the South of France. Based on the combination of four types of building configuration and three classes of vegetation structure, 12 interface types were classified. Through spatial analysis, fire ignition density and burned area ratio were linked with the different types of WUI. Among WUI types, isolated WUIs with the lowest housing density represent the highest level of fire risk. 相似文献
489.
Alexandre M. Martin Hélène Presseault-Gauvin Marco Festa-Bianchet Fanie Pelletier 《Behavioral ecology and sociobiology》2013,67(6):919-928
In males, the acquisition and development of behavioral and morphological secondary sexual traits typically depends on testosterone and correlates with mating success. Testosterone level could affect competition for mates and thus be a target of sexual selection. We sought to relate testosterone levels to male mating competitiveness, by teasing apart the relationships between testosterone, behavior, and growth before the mating period. We monitored 24 adult bighorn rams (Ovis canadensis) at Ram Mountain, Alberta, from 2008 to 2011. Using linear mixed models, we tested the relationships between testosterone metabolites in feces, social rank, and both growth and size of two sexually selected traits: horns and body mass. The correlation between testosterone and social rank varied with age. Testosterone and rank were weakly and negatively correlated for young rams, positively correlated for prime-aged rams, and negatively correlated for older rams. Although testosterone had an increasingly positive effect on total horn length until 8 years of age, we could not detect any effects on annual growth rate of horns or body mass. Testosterone may be related to male’s ability to compete for mates through its relationship with behaviors determining social rank, rather than by influencing the development of morphological traits. Differences in testosterone levels among competitors may be a proximate cause of variance in fitness. 相似文献
490.