全文获取类型
收费全文 | 273篇 |
免费 | 18篇 |
国内免费 | 5篇 |
专业分类
安全科学 | 22篇 |
废物处理 | 7篇 |
环保管理 | 63篇 |
综合类 | 35篇 |
基础理论 | 79篇 |
环境理论 | 1篇 |
污染及防治 | 50篇 |
评价与监测 | 11篇 |
社会与环境 | 17篇 |
灾害及防治 | 11篇 |
出版年
2023年 | 9篇 |
2022年 | 4篇 |
2021年 | 8篇 |
2020年 | 13篇 |
2019年 | 3篇 |
2018年 | 19篇 |
2017年 | 19篇 |
2016年 | 20篇 |
2015年 | 20篇 |
2014年 | 14篇 |
2013年 | 25篇 |
2012年 | 18篇 |
2011年 | 20篇 |
2010年 | 21篇 |
2009年 | 14篇 |
2008年 | 17篇 |
2007年 | 15篇 |
2006年 | 11篇 |
2005年 | 5篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1997年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
排序方式: 共有296条查询结果,搜索用时 7 毫秒
291.
Pablo Jiménez-Bonilla Jessica Salas-Arias Marianelly Esquivel Jose Roberto Vega-Baudrit 《Journal of Polymers and the Environment》2014,22(3):393-397
In Costa Rica, a lot of pineapple (Ananas comosus) and banana (Musa AAA) agroindustrial residues are generated each year. These residues can be used to obtain l-lactic acid by fermentation, ultrafiltration and electrodialysis. Poly(l-lactic acid) (PLLA) is a biodegradable and renewable polyester with many industrial and biomedical applications. There is a growing interest to improve the energetic efficiency of the synthesis of PLLA, because the main issue to produce this polymer is the high productive cost compared with petrochemical traditional commodities. In this research, the synthesis of PLLA through two different techniques was compared: microwave-assisted and conventional heating. On microwave synthesis the best results were obtained using lower temperatures and lower reaction times than the conventional heated synthesis. The reaction time was reduced from 15 h by conventional heating to 4.5 h using microwave-assisted synthesis. 相似文献
292.
293.
Margaret B. Williams Rebecca R.H. Michelsen Jessica L. Axson Laura T. Iraci 《Atmospheric environment (Oxford, England : 1994)》2010,44(9):1145-1151
The solubilities of acetone, ethanol and acetaldehyde in cold ternary solutions composed of 38.4–75.0 wt% sulfuric acid in water with additional dissolved organic material have been measured over the temperature range 214.4–238.5 K using a Knudsen cell reactor. The solubility of acetaldehyde in H2SO4/H2O is enhanced by an order of magnitude by the presence of ethanol or acetone. The reactive uptake of acetaldehyde is enhanced by the presence of formaldehyde in acid solution. No significant formation of acetals from ethanol with carbonyl partners was observed. The solubility of acetone is unaffected by the presence of ethanol in solution and vice versa. Only polymerization of small aldehydes offers a potentially significant route to the accretion of organic material into acidic particles in the upper troposphere. The acid-catalyzed polymerization of aldehydes, RC(H)O + R′C(H)O, proceeds through the hydrated forms of the aldehydes, is optimized at acidities around 40 wt% H2SO4, and can potentially accumulate significant amounts (>20%) of organic material by mass in upper tropospheric particles. 相似文献
294.
Palestina Guevara-Fiore Jessica Stapley Penelope J. Watt 《Behavioral ecology and sociobiology》2010,64(10):1665-1672
Males vary in the degree to which they invest in mating. Several factors can explain this variation, including differences
in males’ individual condition and the fact that males allocate their energy depending on the context they face in each mating
attempt. Particularly, female quality affects male reproductive success. Here, we studied whether male guppies (Poecilia reticulata) strategically allocated more mating effort, in terms of mating behaviour and male–male competition, when they were matched
with a receptive (R) female than a non-receptive one. In accordance with our prediction, we found that males increased their
mating behaviour when they were with a receptive female. Even though male guppies can inseminate non-receptive females, we
only found high levels of courtship between males that were with a receptive female rather than a non-receptive one. Although
there was little affect of female receptivity on male–male competition, we found that males chased and interrupted courtships
more with receptive females than with non-receptive females regardless of odour. Finally, we also studied whether the sexual
pheromone produced by receptive female guppies is a cue that males use in order to increase their mating effort. We found
that males were more attracted to a female when they perceived the sexual pheromone, but only increased their mating and aggressive
behaviours when females showed receptive behaviour. This strategic increase in mating effort could result in higher male reproductive
success because mating attempts towards receptive females are likely to be less costly and males could have a greater probability
of fertilisation. 相似文献
295.
David M. Martin Joshua G. Goldstein David R. Smith Jessica Musengezi Jessie G. Rountree G. A. Pabodha Galgamuwa Aileen Craig Michelle Dietz Caitlin Kerr 《Conservation biology》2023,37(5):e14109
Biodiversity and human well-being strategies are only as good as the set of ideas people think about. We evaluated value-focused thinking (VFT), a framework that emphasizes creating objectives and strategies that are responsive to the objectives. We performed a proof-of-concept study of VFT with 6 conservation planning teams at a global conservation organization. We developed a package of materials related to VFT, including meeting–session agendas, a virtual facilitation template, facilitator's guide, and evaluation questionnaires. We used these materials to test whether VFT applied in a group setting resulted in high-quality conservation strategies and participant satisfaction and whether our materials were scalable, meaning that someone newly trained in VFT could facilitate planning meetings that resulted in high-quality strategies and participant satisfaction, as compared with an experienced VFT facilitator. Net response indicated positive compelling, feasible, creative, and representative ratings for the conservation strategies per team. Participants indicated satisfaction overall, although satisfaction was greater for objectives than for strategies. Among the participants with previous conservation planning experience, all were at least as satisfied with their VFT strategies compared with previously developed strategies, and none were less satisfied (p = 0.001). Changes in participant satisfaction were not related to facilitator type (experienced or inexperienced with VFT) (p > 0.10). Some participants had a preconceived sense of shared understanding of important values and interests before participating in the study, which VFT strengthened. Our results highlight the advantages of structuring the development and evaluation of conservation planning frameworks around VFT. 相似文献
296.
Daniella Rogerson Anna Alkelai Jessica Giordano Madhulatha Pantrangi Meng-Chang Hsiao Chia-Ling Nhan-Chang Joshua E. Motelow Vimla Aggarwal David Goldstein Ron Wapner Carrie J. Shawber 《黑龙江环境通报》2023,43(6):703-716