全文获取类型
收费全文 | 271篇 |
免费 | 2篇 |
国内免费 | 2篇 |
专业分类
安全科学 | 2篇 |
废物处理 | 6篇 |
环保管理 | 24篇 |
综合类 | 151篇 |
基础理论 | 43篇 |
污染及防治 | 34篇 |
评价与监测 | 7篇 |
社会与环境 | 7篇 |
灾害及防治 | 1篇 |
出版年
2021年 | 6篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 7篇 |
2013年 | 8篇 |
2012年 | 9篇 |
2011年 | 8篇 |
2010年 | 12篇 |
2009年 | 6篇 |
2008年 | 7篇 |
2007年 | 7篇 |
2006年 | 7篇 |
2005年 | 4篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1997年 | 4篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1992年 | 3篇 |
1987年 | 3篇 |
1980年 | 3篇 |
1976年 | 3篇 |
1966年 | 3篇 |
1963年 | 5篇 |
1962年 | 7篇 |
1961年 | 3篇 |
1960年 | 8篇 |
1959年 | 4篇 |
1957年 | 5篇 |
1956年 | 5篇 |
1955年 | 4篇 |
1954年 | 3篇 |
1953年 | 2篇 |
1952年 | 3篇 |
1950年 | 2篇 |
1943年 | 3篇 |
1942年 | 2篇 |
1933年 | 4篇 |
1932年 | 4篇 |
1930年 | 4篇 |
1929年 | 5篇 |
1926年 | 3篇 |
1924年 | 3篇 |
1914年 | 2篇 |
1913年 | 4篇 |
排序方式: 共有275条查询结果,搜索用时 0 毫秒
271.
272.
As a result of forcing the energy utilization from biomass, the amounts of combustion residues, especially woodash, are growing. For a sustainable and ecologically effective closed-cycle economy, the knowledge of the chemical composition of the ashes is necessary. The matrix wood ash is very complex, due to the great number of constituents in different concentrations. Therefore it is important to develop a combination of analytical methods for the complete detection of nutrients and heavy metals in wood ash. Ashes from different heating plants (wood chips-, bark-and sawdust combustion systems) were analysed with X-ray methods as well as with acid-digestion in combination with atomic spectrometry detection. The results were compared and checked for their plausibility by statistical methods and material balances for the inorganic elements from the biomass to the ash fractions. As a result of this evaluation astandard method is recommended for the analysis of wood ash. This method consists of a combination of dry (X-ray) analysis (for the elements Si, Ca, Mg, K, P, Al, Fe, Mn) and fluid analysis (for the detection of heavy metals). 相似文献
273.
Cardoso NF Lima EC Pinto IS Amavisca CV Royer B Pinto RB Alencar WS Pereira SF 《Journal of environmental management》2011,92(4):1237-1247
The cupuassu shell (Theobroma grandiflorum) which is a food residue was used in its natural form as biosorbent for the removal of C.I. Reactive Red 194 and C.I. Direct Blue 53 dyes from aqueous solutions. This biosorbent was characterized by infrared spectroscopy, scanning electron microscopy, and nitrogen adsorption/desorption curves. The effects of pH, biosorbent dosage and shaking time on biosorption capacities were studied. In acidic pH region (pH 2.0) the biosorption of the dyes were favorable. The contact time required to obtain the equilibrium was 8 and 18 h at 298 K, for Reactive Red 194 and Direct Blue 53, respectively. The Avrami fractionary-order kinetic model provided the best fit to experimental data compared with pseudo-first-order, pseudo-second-order and chemisorption kinetic adsorption models. The equilibrium data were fitted to Langmuir, Freundlich, Sips and Radke-Prausnitz isotherm models. For both dyes the equilibrium data were best fitted to the Sips isotherm model. 相似文献
274.
275.
Speciation—the origin of new species—is the source of the diversity of life. A theory of speciation is essential to link poorly
understood macro-evolutionary processes, such as the origin of biodiversity and adaptive radiation, to well understood micro-evolutionary
processes, such as allele frequency change due to natural or sexual selection. An important question is whether, and to what
extent, the process of speciation is ‘adaptive’, i.e., driven by natural and/or sexual selection. Here, we discuss two main
modelling approaches in adaptive speciation theory. Ecological models of speciation focus on the evolution of ecological differentiation
through divergent natural selection. These models can explain the stable coexistence of the resulting daughter species in
the face of interspecific competition, but they are often vague about the evolution of reproductive isolation. Most sexual
selection models of speciation focus on the diversification of mating strategies through divergent sexual selection. These
models can explain the evolution of prezygotic reproductive isolation, but they are typically vague on questions like ecological
coexistence. By means of an integrated model, incorporating both ecological interactions and sexual selection, we demonstrate
that disruptive selection on both ecological and mating strategies is necessary, but not sufficient, for speciation to occur.
To achieve speciation, mating must at least partly reflect ecological characteristics. The interaction of natural and sexual
selection is also pivotal in a model where sexual selection facilitates ecological speciation even in the absence of diverging
female preferences. In view of these results, it is counterproductive to consider ecological and sexual selection models as
contrasting and incompatible views on speciation, one being dominant over the other. Instead, an integrative perspective is
needed to achieve a thorough and coherent understanding of adaptive speciation. 相似文献