全文获取类型
收费全文 | 669篇 |
免费 | 7篇 |
专业分类
安全科学 | 14篇 |
废物处理 | 42篇 |
环保管理 | 51篇 |
综合类 | 87篇 |
基础理论 | 130篇 |
污染及防治 | 248篇 |
评价与监测 | 62篇 |
社会与环境 | 41篇 |
灾害及防治 | 1篇 |
出版年
2023年 | 4篇 |
2022年 | 11篇 |
2021年 | 21篇 |
2020年 | 5篇 |
2019年 | 7篇 |
2018年 | 18篇 |
2017年 | 17篇 |
2016年 | 45篇 |
2015年 | 20篇 |
2014年 | 41篇 |
2013年 | 45篇 |
2012年 | 43篇 |
2011年 | 58篇 |
2010年 | 45篇 |
2009年 | 39篇 |
2008年 | 50篇 |
2007年 | 45篇 |
2006年 | 37篇 |
2005年 | 24篇 |
2004年 | 18篇 |
2003年 | 18篇 |
2002年 | 16篇 |
2001年 | 12篇 |
2000年 | 8篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1964年 | 2篇 |
1963年 | 1篇 |
1961年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有676条查询结果,搜索用时 31 毫秒
161.
The establishment of fighting rules and the ability to recognise individual conspecifics and to assess their fighting ability
and/or roles may help to reduce costs of fighting. We staged encounters between males of the lizard Podarcis hispanica to examine whether lizards used fighting strategies and whether a previous agonistic experience affects the outcome and characteristics
of a subsequent encounter. The results showed that simple rules such as body size differences and residence condition were
used to determine the outcome of agonistic interactions as quickly as possible. Thus, larger males were dominant in most encounters.
However, when size differences between opponents are smaller, they may be more difficult to estimate and, then, residence
condition was more important. In addition, the intensity of interactions between males could be explained according to the
”sequential assessment game”, supporting the idea that P. hispanica males acquire information about fighting ability gradually during the progress of a fight. Our results also showed that the
second fight of the same pair of males was less aggressive, even when its outcome was the opposite of the first. This result
suggests that male P. hispanica can recognise individual opponents and that they use this information to reach a contest outcome more quickly, thus reducing
unnecessary aggression levels in subsequent interactions. These fighting strategies and assessment mechanisms may help to
stabilise the social system of this lizard.
Received: 2 November 1999 / Revised: 26 August 2000 / Accepted: 4 September 2000 相似文献
162.
Srimalanon Panupong Martín-Fabiani Ignacio Prapagdee Benjaphorn Markpin Teerasak Wimolmala Ekachai Sombatsompop Narongrit 《Journal of Material Cycles and Waste Management》2021,23(5):1893-1904
Journal of Material Cycles and Waste Management - A spontaneous combination of hygienic in situ compatibilized polybutylene succinate/polylactic acids (PBS/PLA) was formulated through the addition... 相似文献
163.
Juan C. Alonso Carlos Palacín Javier A. Alonso Carlos A. Martín 《Behavioral ecology and sociobiology》2009,63(12):1705-1715
Radio tracking of 142 males captured at 44 leks in Spain showed that partial migration of great bustard males in summer is
a widespread behaviour in many Iberian populations, in contrast to their previously assumed sedentariness. A variable number
of males migrated immediately after mating to summering areas with lower temperatures and human population densities and more
trees and rainfall levels than the breeding sites. Birds selected there fields with trees and sunflower crops which provided
shade during the hottest midday hours and protective cover against predators. Males breeding in areas with higher July temperatures
had a higher tendency to migrate, and males from hotter, southern regions migrated longer distances than those from milder,
northern regions and showed a preferred northward direction. These results confirmed various predictions from the weather
sensitivity hypothesis, suggesting that summer migration of great bustard males represents primarily an adaptation to escape
the summer heat of most breeding areas in central and southern Iberia. The hypothesis that males migrated to benefit from
higher food availability at the summering areas could not be rejected by our results. Finally, migrating males also gained
more tranquillity during the post-breeding moult due to the lower human population density at the summering areas. Summer
migration of Iberian great bustard males may thus be interpreted as a form of behavioural thermoregulation which has not been
described for other Palaearctic populations of this species or for other bird species breeding in temperate latitudes. 相似文献
164.
Jiří Kopáček Jan Turek Josef Hejzlar Hana Šantrůčková 《Atmospheric environment (Oxford, England : 1994)》2009,43(34):5443-5453
Precipitation and throughfall fluxes of major ions, nutrients (C, N, P), and metals (Al, Fe, Mn), and the chemical composition of litter fall and living plant tissue in Norway spruce stands (the Bohemian Forest; Czech Republic), were used to evaluate how microbial processes and decay of plant tissue in canopies influence canopy leaching (CL) of elements. Proton exchange for Mg2+, Ca2+, and K+ in decaying biomass and co-transport of Ca2+ and K+ out of plant cells with organic acid anions were the most likely processes contributing to CL of base cations. The CL of total P and N (and also NO3?) was minor. Important proportions of the N and P mineral forms were transformed to organic forms by microbial processes (primary and bacterial production), with the respective CL of ?13.9 and 16.4 mmol m?2 yr?1 for NH4+ and organic N, and ?0.33 and 0.22 mmol m?2 yr?1 for dissolved reactive P (DRP) and organic P. Most of particulate P and N in throughfall (~90%) originated from microbial DRP and NH4+ transformations, but particulate C mostly came from the fragmentation of plant tissue (58%). Among metals, CL was not observed for Al, was small for Fe (0.3 mmol m?2 yr?1), and greatest for Mn (0.9 mmol m?2 yr?1) due to leaching from decaying tissue by acidic precipitation. 相似文献
165.
A study of the second step or methanogenic stage of a two-stage anaerobic digestion process treating two-phase olive oil mill solid residue (OMSR) was conducted at mesophilic temperature (35 °C). The substrate fed to the methanogenic step was the effluent from a hydrolytic–acidogenic reactor operating at an organic loading rate (OLR) of 12.9 g chemical oxygen demand (COD) L?1 d?1 and at a hydraulic retention time (HRT) of 12.4 days; these OLR and HRT were found to be the best values to achieve the maximum total volatile fatty acid concentration (14.5 g L?1 expressed as acetic acid) with a high concentration in acetic acid (57.5% of the total concentration) as the principal precursor of methane. The methanogenic stage was carried out in an anaerobic stirred tank reactor containing saponite as support media for the immobilization of microorganisms. OLRs of between 0.8 and 22.0 g COD L?1 d?1 were studied. These OLRs corresponded to HRTs of between 142.9 and 4.6 days. The methanogenic reactor operated with high stability for OLRs lower than 20.0 g COD L?1 d?1. This behaviour was shown by the total volatile fatty acids/total alkalinity ratio, whose values were always kept ?0.12 for HRTs > 4.6 days. The total COD (T-COD) removed was in the range of 94.3–61.3% and the volatile solids (VS) removed between 92.8% and 56.1% for OLRs between 0.8 and 20.0 g COD L?1 d?1. In the same way, a reduction of 43.8% was achieved for phenolic content. The low concentration of total volatile fatty acids (TVFA) observed (below 1 g L?1 expressed as CH3COOH) in the methanogenic reactor effluents showed the high percentage of consumption and conversion of these acids to methane. A methane yield of 0.268 ± 0.003 L CH4 at standard temperature and pressure conditions (STP) g?1 COD eliminated was achieved. 相似文献
166.
José A. Martínez-Casasnovas María Concepción Ramos Sílvia Espinal-Utgés 《Environmental monitoring and assessment》2010,163(1-4):379-396
The availability of heavy machinery and the vineyard restructuring and conversion plans of the European Union Common Agricultural Policy (Commission Regulation EC no. 1227/2000 of 31 May 2000) have encouraged the restructuring of many vineyards on hillslopes of Mediterranean Europe, through the creation of terraces to favor the mechanization of agricultural work. Terrace construction requires cutting and filling operations that create soil spatial variability, which affects soil properties and plant development. In the present paper, we study the effects of hillslope terracing on the spatial variability of the normalized difference vegetation index (NDVI) in fields of the Priorat region (NE Spain) during 2004, 2005, and 2006. This index was computed from high-resolution remote sensing data (Quickbird-2). Detailed digital terrain models before and after terrace construction were used to assess the earth movements. The results indicate that terracing by heavy machinery induced high variability on the NDVI values over the years, showing significant differences as effect of the cut and fill operations. 相似文献
167.
168.
The significance of waste management systems in recent years increased due to the growing problems of waste management chains affecting the daily lives of millions of people and the impact on the environment. Several promising approaches have been developed in the past few years. One of them is the waste management system modelling using reliability, availability, maintainability and safety software. This paper analyses and evaluates this approach. The main goal is to provide quantitative forecasts for various performance measures of waste management systems. They include availability, downtimes, number of failures, and cost. Evaluation of these measures is important for optimal decision making. The system design should both maximise the system performance leading to cleaner processing and minimise the overall cost within the allowable constraints. The effectiveness of this methodology is demonstrated through a case study. 相似文献
169.
Life Cycle Assessment (LCA) is a well-known tool for analyzing environmental impacts on a wide perspective with reference to a product system and the related environmental and economic impacts. The need for a novel approach that complements environmental and financial considerations is addressed in this study with the introduction of a new graphical representation: the Environmental Performance Strategy Map. This graphical map allows one to combine the main environmental indicators (footprints) with the additional dimension of cost. The paper defines the Sustainable Environmental Performance Indicator as a single measure for sustainability of a given option. Comparison of different options for strategic decision-making purposes can be enhanced and facilitated by the use of this indicator. 相似文献
170.
Petra Quillfeldt Javier Martínez Janos Hennicke Katrin Ludynia Anja Gladbach Juan F. Masello Samuel Riou Santiago Merino 《Die Naturwissenschaften》2010,97(9):809-817
Whereas some bird species are heavily affected by blood parasites in the wild, others reportedly are not. Seabirds, in particular,
are often free from blood parasites, even in the presence of potential vectors. By means of polymerase chain reaction, we
amplified a DNA fragment from the cytochrome b gene to detect parasites of the genera Plasmodium, Leucocytozoon, and Haemoproteus in 14 seabird species, ranging from Antarctica to the tropical Indian Ocean. We did not detect parasites in 11 of these species,
including one Antarctic, four subantarctic, two temperate, and four tropical species. On the other hand, two subantarctic
species, thin-billed prions Pachyptila belcheri and dolphin gulls Larus scoresbii, were found infected. One of 28 thin-billed prions had a Plasmodium infection whose DNA sequence was identical to lineage P22 of Plasmodium relictum, and one of 20 dolphin gulls was infected with a Haemoproteus lineage which appears phylogenetically clustered with parasites species isolated from passeriform birds such as Haemoproteus lanii, Haemoproteus magnus, Haemoproteus fringillae, Haemoproteus sylvae, Haemoproteus payevskyi, and Haemoproteus belopolskyi. In addition, we found a high parasite prevalence in a single tropical species, the Christmas Island frigatebird Fregata andrewsi, where 56% of sampled adults were infected with Haemoproteus. The latter formed a monophyletic group that includes a Haemoproteus line from Eastern Asian black-tailed gulls Larus crassirostris. Our results are in agreement with those showing that (a) seabirds are poor in hemosporidians and (b) latitude could be a
determining factor to predict the presence of hemosporidians in birds. However, further studies should explore the relative
importance of extrinsic and intrinsic factors on parasite prevalence, in particular using phylogenetically controlled comparative
analyses, systematic sampling and screening of vectors, and within-species comparisons. 相似文献