全文获取类型
收费全文 | 409篇 |
免费 | 12篇 |
国内免费 | 5篇 |
专业分类
安全科学 | 28篇 |
废物处理 | 10篇 |
环保管理 | 57篇 |
综合类 | 48篇 |
基础理论 | 73篇 |
污染及防治 | 126篇 |
评价与监测 | 52篇 |
社会与环境 | 25篇 |
灾害及防治 | 7篇 |
出版年
2023年 | 7篇 |
2022年 | 19篇 |
2021年 | 10篇 |
2020年 | 8篇 |
2019年 | 12篇 |
2018年 | 19篇 |
2017年 | 20篇 |
2016年 | 22篇 |
2015年 | 16篇 |
2014年 | 9篇 |
2013年 | 53篇 |
2012年 | 19篇 |
2011年 | 28篇 |
2010年 | 30篇 |
2009年 | 16篇 |
2008年 | 13篇 |
2007年 | 15篇 |
2006年 | 19篇 |
2005年 | 13篇 |
2004年 | 4篇 |
2003年 | 9篇 |
2002年 | 9篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1993年 | 5篇 |
1991年 | 4篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1972年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1965年 | 1篇 |
1958年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有426条查询结果,搜索用时 31 毫秒
401.
Successful management in competitive markets requires evaluation methods that respond to global market dynamics and provide investors with relevant information to make strategic investment decisions. These strategic decisions include decisions on investment timing, feasibility study and risk management and mine operating options. Conventional methods do not have the built-in capabilities to help investors handle these strategic issues. Advances in modern finance have had profound impacts on financial markets for options, futures and collaterized securities and offer appropriate tools in solving these problems. In this paper, the authors have extended the Brennan and Schwartz mineral resource model to develop the derivative mine valuation method based on the dynamic arbitrage theory. A copper mining venture has been evaluated using the derivative mine valuation and conventional methods. The results show that the derivative mine valuation method allows investors to maximize the venture's market value by exercising these strategic options. 相似文献
402.
Data obtained from full‐time employees of a public sector organization in India were used to test a social exchange model of employee work attitudes and behaviors. LISREL results revealed that whereas the three organizational justice dimensions (distributive, procedural and interactional) were related to trust in organization only interactional justice was related to trust in supervisor. The results further revealed that relative to the hypothesized fully mediated model a partially mediated model better fitted the data. Trust in organization partially mediated the relationship between distributive and procedural justice and the work attitudes of job satisfaction, turnover intentions, and organizational commitment but fully mediated the relationship between interactional justice and these work attitudes. In contrast, trust in supervisor fully mediated the relationship between interactional justice and the work behaviors of task performance and the individually‐ and organizationally‐oriented dimensions of citizenship behavior. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
403.
Samuel N Addy 《Resources Policy》1998,24(4):229-239
After almost two decades of decline, Ghana's mineral sector has rebounded significantly and is currently the main foreign exchange earner. Gold mining is the principal activity within the sector and accounted for 41 percent of total export earnings in 1996. This paper presents an overview of Ghana's mineral industry and covers mineral resources, production and reserves; mining investments; the role of mining in the economy; and the structure of the industry. An overview of the national mineral policy is also presented to depict the current regulatory and fiscal environment in which the industry operates. The spectacular reversal in mineral sector performance can be attributed to the adoption of World Bank recommendations in a new national mineral policy, the 1986 Minerals and Mining Law, aimed at revitalizing the sector. 相似文献
404.
Owoyemi Jacob Mayowa Opara Emmanuel Uchechukwu Akande Samuel Olumide Olarenwaju Joshua Tosin Fuwape Joseph Adeola 《Environment, Development and Sustainability》2022,24(8):10309-10336
Environment, Development and Sustainability - Siting of buildings in rural urban development requires that the prevalence of termite activities is considered. The severity of termite activities... 相似文献
405.
406.
The solubility data for a series of non‐hydrogen bonding, monosubstituted benzenes in binary mixtures of water and non‐hydrogen bonding cosolvents is presented. Good correlation between log solubility and fraction cosolvent is obtained, therefore the estimation of solubility in mixed solvents by a log‐linear relationship can be attained. Slight positive or negative deviations from predicted solubility values are seen at high volume fractions of cosolvents. These deviations are attributed to the cosolvent‐water interactions. 相似文献
407.
Plant growth rates and seed size: a re-evaluation 总被引:1,自引:0,他引:1
Turnbull LA Philipson CD Purves DW Atkinson RL Cunniff J Goodenough A Hautier Y Houghton J Marthews TR Osborne CP Paul-Victor C Rose KE Saner P Taylor SH Woodward FI Hector A Rees M 《Ecology》2012,93(6):1283-1289
Small-seeded plant species are often reported to have high relative growth rate or RGR. However, because RGR declines as plants grow larger, small-seeded species could achieve higher RGR simply by virtue of their small size. In contrast, size-standardized growth rate or SGR factors out these size effects. Differences in SGR can thus only be due to differences in morphology, allocation, or physiology. We used nonlinear regression to calculate SGR for comparison with RGR for 10 groups of species spanning a wide range of life forms. We found that RGR was negatively correlated with seed mass in nearly all groups, but the relationship between SGR and seed mass was highly variable. We conclude that small-seeded species only sometimes possess additional adaptations for rapid growth over and above their general size advantage. 相似文献
408.
Wilson Y. Fantong Hiroshi Satake Samuel N. Ayonghe Emmanuel C. Suh Segun M. A. Adelana Emilia Bi S. Fantong Hycinth S. Banseka Cletus D. Gwanfogbe Leonard N. Woincham Yoshitoshi Uehara Jing Zhang 《Environmental geochemistry and health》2010,32(2):147-163
The 500,000 inhabitants of Mayo Tsanaga River Basin are vulnerable to a “silent” fluorosis from groundwater consumption. For the first time, the groundwater is investigated for the purpose of identifying the provenance of fluoride and estimating an optimal dose of fluoride in the study area. Based on the fluoride content of groundwater, fluorine and major oxides abundances in rocks from the study area, mean annual atmospheric temperature, and on-site diagnosis of fluorosis in children, the following results and conclusions are obtained: Fluoride concentration in groundwater ranges from 0.19 to 15.2 mg/l. Samples with fluoride content of <1.5 mg/l show Ca–HCO3 signatures, while those with fluoride >1.5 mg/l show a tendency towards Na-HCO3 type. Fluor-apatite and micas in the granites were identified as the main provenance of fluoride in the groundwater through water-rock interactions in an alkaline medium. The optimal fluoride dose in drinking water of the study area should be 0.7 mg/l, and could be adjusted downward to a level of 0.6 mg/l due to the high consumption rate of groundwater, especially during drier periods. 相似文献
409.
Bottom trawling is associated with reduced biomass and production in the marine benthic community. Abundance of hard-bodied
organisms such as bivalves, crustaceans and echinoderms typically declines in favour of soft-bodied opportunists such as polychaetes.
Trawling effects vary with habitat; impact and recovery time are typically greater for more complex substrates/communities
and those with lower rates of natural disturbance. Benthic organisms represent the prey base of a large component of the demersal
fish assemblage. Hence, trawling-induced change in benthic community structure and function may exert an indirect effect on
feeding success and growth of important commercially exploited fishes such as plaice Pleuronectes platessa. We present habitat-specific mixed effects models of plaice length as a function of age, bottom-trawling effort, population
density and near-bottom temperature, with sampling year and area, and fish sex incorporated as random effects. Across an observed
gradient of trawling effort in the Celtic Sea, plaice on gravel habitat showed significant declines in length at age while
plaice on sand habitat showed significant increases in length at age. Contrasting trawling effects likely reflect dietary
differences between habitats. Plaice on sand substrates are known to consume predominately polychaetes, which may proliferate
at moderate trawling intensity in this habitat. Conversely, plaice on gravel substrates are reported to consume more of the
fragile organisms such as echinoderms and bivalves that show marked declines with bottom trawling. An indirect effect of trawling
on prey availability and growth of demersal fish has substantial implications for fisheries sustainability via reduced ecosystem
carrying capacity and production of commercial fish. 相似文献
410.
In order to avoid environmental threats, organisms may respond by altering behavior or phenotype. Using experiments performed in high-latitude Siberia and in temperate Sweden, we show for the first time that, among freshwater crustacean zooplankton, the defense against threats from ultraviolet radiation (UV) is a system where phenotypic plasticity and behavioral escape mechanisms function as complementary traits. Freshwater copepods relied mainly on accumulating protective pigments when exposed to UV radiation, but Daphnia showed strong behavioral responses. Pigment levels for both Daphnia and copepods were generally higher at higher latitudes, mirroring different UV threat levels. When released from the UV threat, Daphnia rapidly reduced (within 10 days) their UV protecting pigmentation-by as much as 40%--suggesting a cost in maintaining UV protective pigmentation. The evolutionary advantage of protective pigments is, likely, the ability to utilize the whole water column during daytime; conversely, since the amount of algal food is generally higher in surface waters, unpigmented individuals are restricted to a less preferred feeding habitat in deeper waters. Our main conclusion is that different zooplankton taxa, and similar taxa at different latitudes, use different mixes of behavior and pigments to respond to UV radiation. 相似文献