全文获取类型
收费全文 | 579篇 |
免费 | 16篇 |
国内免费 | 10篇 |
专业分类
安全科学 | 16篇 |
废物处理 | 38篇 |
环保管理 | 111篇 |
综合类 | 98篇 |
基础理论 | 163篇 |
环境理论 | 4篇 |
污染及防治 | 97篇 |
评价与监测 | 50篇 |
社会与环境 | 25篇 |
灾害及防治 | 3篇 |
出版年
2023年 | 5篇 |
2022年 | 6篇 |
2021年 | 11篇 |
2020年 | 11篇 |
2019年 | 12篇 |
2018年 | 14篇 |
2017年 | 22篇 |
2016年 | 31篇 |
2015年 | 25篇 |
2014年 | 24篇 |
2013年 | 53篇 |
2012年 | 40篇 |
2011年 | 40篇 |
2010年 | 26篇 |
2009年 | 36篇 |
2008年 | 27篇 |
2007年 | 22篇 |
2006年 | 28篇 |
2005年 | 18篇 |
2004年 | 14篇 |
2003年 | 15篇 |
2002年 | 15篇 |
2001年 | 9篇 |
2000年 | 8篇 |
1999年 | 11篇 |
1998年 | 7篇 |
1997年 | 9篇 |
1996年 | 4篇 |
1995年 | 8篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1976年 | 1篇 |
1974年 | 3篇 |
1961年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有605条查询结果,搜索用时 804 毫秒
211.
212.
Isabel M. Jimenez Anthony W. D. Larkum Peter J. Ralph Michael Kühl 《Marine Biology》2012,159(8):1773-1782
We studied the diel variation of in situ coral temperature, irradiance and photosynthetic performance of hemispherical colonies of Porites lobata and branching colonies of Porites cylindrica during different bulk water temperature and tidal scenarios on the shallow reef flat of Heron Island, Great Barrier Reef, Australia. Our study presents in situ evidence that coral tissue surface temperatures can exceed that of the surrounding water under environmental conditions typically occurring during low tide in shallow reef or lagoon environments. Such heating may be a regular occurrence on shallow reef flats, triggered by the combined effects of high irradiance and low water flow characteristic of low Spring tides. At these times, solar heating of corals coincides with times of maximum water temperature and high irradiance, where the slow flow and consequent thick boundary layers impede heat exchange between corals and the surrounding water. Despite similar light-absorbing properties, the heating effect was more pronounced for the hemispherical P. lobata than for the branching P. cylindrica. This is consistent with previous laboratory experiments showing the evidence of interspecific variation in coral thermal environment and may result from morphologically influenced variation in convective heat transfer and/or thermal properties of the skeleton. Maximum coral surface warming did not coincide with maximum irradiance, but with maximum water temperature, well into the low-tide period with extremely low water flow in the partially drained reef flat, just prior to flushing by the rising tide. The timing of low tide thus influences the thermal exposure and photophysiological performance of corals, and the timing of tidally driven coral surface warming could potentially have different physiological impacts in the morning or in the afternoon. 相似文献
213.
The desire to avoid rousing community hostility may encourage firms to behave in an environmentally responsible manner. Firms may engage in corporate social responsibility (CSR) to maintain community support and/or to regain the support of a community where it has been lost. It has been conjectured that such ‘informal regulation’ could effectively replace formal intervention in some settings, and usefully complement it in others. We explore these conjectures with mixed results. Informal regulation is necessarily less efficient than a well-designed formal alternative and the pattern of green behavior induced by the threat of community hostility may increase or decrease welfare. The existence of community pressure may increase or decrease the optimal calibration of a formal intervention (in this case an environmental tax) and may complement or detract from the incentives generated by an optimally calibrated tax. 相似文献
214.
The relationship between plant nutrient content and insect herbivore populations and community structure has long interested ecologists. Insect herbivores require multiple nutrients, but ecologists have focused mostly on nitrogen (an estimate of plant protein content), and more recently phosphorus (P); other nutrients have received little attention. Here we document nutrient variation in grass and forb samples from grassland habitats in central Nebraska using an elemental approach; in total we measured foliar concentrations of 12 elements (N and P, plus S, B, Ca, Mg, Na, K, Zn, Fe, Mn, and Cu). We detected significant variability among sites for N, P, Mg, Na, K, and Cu. We next used a model selection approach to explore how this nutritional variation and plant biomass correlate with grasshopper densities (collectively and at the feeding-guild level), and principal component analysis to explore nutrient correlations with grasshopper community species composition. When all grasshoppers were pooled, densities varied among sites, but only P was associated with abundance of the elements shown to vary between sites. Different responses occurred at the feeding-guild level. For grass specialists, densities were associated with N, plus P, Mg, and Na. For forb specialists, N and P were often associated with density, but associations with Na and K were also observed. Finally, mixed-feeder abundance was strongly associated with biomass, and to a lesser extent P, Mg, Na, and Cu. At the community level, B, Ca, Zn, and Cu, plus biomass, explained > 30% of species composition variation. Our results confirm the positive association of N and P with insect herbivore populations, while suggesting a potential role for Mg, Na, and K. They also demonstrate the importance of exploring effects at the feeding-guild level. We hope our data motivate ecologists to think beyond N and P when considering plant nutrient effects on insect herbivores, and make a call for studies to examine functional responses of insect herbivores to dietary manipulation of Mg, Na, and K. Finally, our results demonstrate correlations between variation in nutrients and species assemblages, but factors not linked to plant nutrient quality or biomass likely explain most of the observed variation. 相似文献
215.
Sebastian?LeuzingerEmail author Bette?L.?Willis Kenneth?R.?N.?Anthony 《Marine Biology》2012,159(1):177-186
An organism’s pattern of resource allocation to reproduction and growth over time critically impacts on its lifetime reproductive
success. During times of low resource availability, there are two fundamental, mutually exclusive strategies of energy investment:
maintenance of somatic tissues to support survival and later reproduction or investment into an immediate reproductive event
at the risk of subsequent death. Here, we examine energy allocation patterns in the coral Montipora digitata to determine whether energy investment during periods of resource shortage favours growth or reproduction in a sessile, modular
marine species. We manipulated light regimes (two levels of shading) on plots within a shallow reef flat habitat (Orpheus
Island, Great Barrier Reef, Australia) and quantified energy uptake (rates of net photosynthesis), energy investment into
reproduction (E
R
), tissue growth per unit surface area (E
T
) and energy channelled into calcification (E
C
). With declining resource availability (i.e. reduced photosynthesis), relative energy investment shifted from high (~80%)
allocation to tissue growth (E
R
:E
T
:E
C
= 11:81:8%) to an increasing proportion channelled into reproduction and skeletal growth (20:31:49%). At the lowest light
regime, calcification was maintained but reproduction was halted and thus energy content per unit surface area of tissue declined,
although no mortality was observed. The changing hierarchy in energy allocation among life functions with increasing resource
limitation found here for an autotrophic coral, culminating in cessation of reproduction when limitations are severe, stands
in contrast to observations from annual plants. However, the strategy may be optimal for maximising fitness components (growth,
reproduction and survival) through time in marine modular animals. 相似文献
216.
The purpose of this study was to determine the copper (Cu) biosorption capacities of several agricultural wastes from aqueous solutions. Samples of agricultural wastes were tested unaltered and after hydrochloric acid (HCl) treatment. Additional parameters tested include sample dose, contact time, particle size, mixing temperature, and the concentrations and pH of the Cu solutions. Desorption studies were performed to determine if the removed Cu could be recovered. In addition, tests were conducted to determine if the agricultural waste samples (AWS) could be reused for additional Cu biosorption cycles. The results of this study demonstrate a wide range of Cu biosorption proficiencies ranging from 0% to 100% removal. The parameters that resulted in higher Cu removal include higher pH and lower Cu solution concentration. Desorption results showed a 58% to 86% Cu recovery rate. Three of the five reused AWS were effective at removing Cu during subsequent trials. Therefore, these AWS types can be reused for additional Cu biosorption cycles. Hence, it is possible that using those AWS for metal treatment could reduce hazardous waste disposal inefficiencies and costs by avoiding disposing of spent AWS following each Cu biosorption cycle. 相似文献
217.
Although the prevalence of employees working within the same workplace or occupation with their spouse has increased, relatively little research has examined their experiences. On the basis of the boundary and conservation of resources (COR) theories, we argue that higher levels of work–family role integration among work‐linked couples will lead to higher levels of spousal support resources and lower levels of work–family conflict. This will, in turn, lead to lower emotional exhaustion among employees in a work‐linked relationship. Among two samples of employees in a variety of occupations, we found that being in a work‐linked relationship was associated with both higher spousal instrumental support as well as different forms of work–family conflict. The interaction between spousal support and work–family conflict was associated with emotional exhaustion. We discuss the implications of these findings for boundary and COR theories in terms of movement of resources across work–family boundaries and resource relevance in the strain process. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
218.
Enforcement of policy is typically delegated. What sort of mission should the head of an enforcement program be given? When there is more than one firm being regulated the firms’ decision problems—otherwise completely separate—become linked in a way that depends on that mission. Under some sorts of missions firms compete to avoid the attention of the enforcer by competitive reductions in the extent of their non-compliance, in others the interaction encourages competitive expansions. We develop a general model that allows for the ordering of some typical classes of missions. We find that in plausible settings ‘target-driven’ missions (that set a hard target in terms of environmental outcome but flexible budget) achieve the same outcome at lower cost than ‘budget-driven’ ones (that fix the enforcement budget). Inspection of some fixed fraction of firms is never optimal. 相似文献
219.
Liza R. Moscovice Marlies Heesen Anthony Di Fiore Robert M. Seyfarth Dorothy L. Cheney 《Behavioral ecology and sociobiology》2009,63(10):1471-1482
Adult male chacma baboons (Papio hamadryas ursinus) form preferential associations, or friendships, with particular lactating females. Males exhibit high levels of affiliative
contact with their friends’ infants and defend them from potentially infanticidal attacks (Palombit et al. 1997). Little is known about males’ associations with juveniles once they have passed the period of infanticidal risk. We conducted
an observational, experimental, and genetic study of adult male and juvenile chacma baboons in the Moremi Reserve, Botswana.
We identified preferential associations between males and juveniles and used behavioral data and a playback experiment to
explore whether those associations have potential fitness benefits for juveniles. We determined whether males preferentially
invest in care of their own offspring. We also determined how often males invest in care of their former friends’ offspring.
The majority of juveniles exhibited preferential associations with one or two males, who had almost always been their mother’s
friend during infancy. However, in only a subset of these relationships was the male the actual father, in part because many
fathers died or disappeared before their offspring were weaned. Male caretakers intervened on behalf of their juvenile associates
in social conflicts more often than they intervened on behalf of unconnected juveniles, and they did not appear to differentiate
between genetic offspring and unrelated associates. Playbacks of juveniles’ distress calls elicited a stronger response from
their caretakers than from control males. Chacma males may provide care to unrelated offspring of former friends because the
costs associated with such care are low compared with the potentially high fitness costs of refusing aid to a juvenile who
is a possible offspring. 相似文献
220.
Field test of best management practice pollutant removal efficiencies in Shenzhen, China 总被引:1,自引:0,他引:1
Ru ZHANG Wenbin ZHOU Richard FIELD Anthony TAFURI Shaw L. YU Keli JIN 《Frontiers of Environmental Science & Engineering》2009,3(3):354-363
This paper presents a study on the use of best management practices (BMPs) for controlling nonpoint pollution in the Xikeng Reservoir watershed located in Shenzhen, China. A BMP treatment train design, including a pond, a wetland, and a buffer strip placed in series was implemented at the reservoir location. A separate grass swale was also constructed at the site. Low impact development (LID) BMPs, namely a planter box and bioboxes, were used at the parking lot of the reservoir’s Administration Building. Samples were collected during storm events and were analyzed for total suspended solids (TSS), biochemical oxygen demand (BOD5), ammonia nitrogen (NH3—N), and total phosphorus (TP). The removal efficiencies of both BMP systems were evaluated using the Efficiency Ratio (ER) method based on the event mean concentration (EMC) data. In summary, the pond/wetland treatment train removed 70%―90% of TSS, 20%―50% of BOD5, and 30%―70% of TP and NH3—N. The swale removed 50%―90% of TSS, 30%―55% of BOD5, −10%―35% of NH3—N, and 25%―70% of TP. For the planter box and biobox, the ranges of removal rates were 70%―90%, 20%―50%, and 30%―70% for TSS, BOD5, and ammonia and phosphorus, respectively. 相似文献