全文获取类型
收费全文 | 70篇 |
免费 | 5篇 |
国内免费 | 6篇 |
专业分类
安全科学 | 6篇 |
环保管理 | 13篇 |
综合类 | 26篇 |
基础理论 | 7篇 |
环境理论 | 1篇 |
评价与监测 | 1篇 |
社会与环境 | 23篇 |
灾害及防治 | 4篇 |
出版年
2024年 | 2篇 |
2023年 | 2篇 |
2022年 | 6篇 |
2021年 | 5篇 |
2020年 | 1篇 |
2019年 | 7篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 12篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2013年 | 2篇 |
2012年 | 9篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2006年 | 1篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 1篇 |
排序方式: 共有81条查询结果,搜索用时 31 毫秒
51.
Various approaches have been proposed for allocating commitments to countries regarding the mitigation of greenhouse gas emissions. One of these methods is the ‘contraction and convergence’ approach, which defines emission permits on the basis of converging per capita emissions under a contracting global emission profile. The approach is unique in its simplicity. Only two major issues need to be negotiated and agreed upon: the target atmospheric concentration of CO2 and the date when the entitlements are to converge at equal per capita allocations. According to the contraction and convergence approach, developing countries can continue their current emission trends, whereas industrialized countries should reduce their emissions quite dramatically. This regime represents a shift away from the current approach towards defining commitments for all parties and their evolution over the long term. This article analyses how allocation schemes determined by the contraction and convergence approach might affect certain OECD and non‐OECD countries. Results for eleven countries selected for analysis (United States, United Kingdom, Germany, France, Japan, China, Venezuela, Thailand, Brazil, India and Indonesia) reveal that trends observed in the past few decades in most industrialized countries will lead to the contraction and convergence target. 相似文献
52.
Stephanie?L.?WatwoodEmail author Peter?L.?Tyack Randall?S.?Wells 《Behavioral ecology and sociobiology》2004,55(6):531-543
The signature whistle hypothesis states that dolphins produce highly stereotyped, individually distinctive whistles when in isolation. The presence of signature whistles has been called into question by recent studies proposing that dolphins produce a shared, simple upsweep whistle when in isolation, and that whistles produced by socializing dolphins are shared across individuals and social groups. This shared repertoire hypothesis suggests that when two animals produce the same whistle type, it is due to sharing the same common repertoire rather than one animal learning to produce the whistle of another. One difference between studies supporting or denying the existence of signature whistles is the method used to classify whistle types. We examined whistle production by 17 free-ranging bottlenose dolphins while temporarily restrained. We used both a quantitative comparison technique similar to that used to support the shared repertoire hypothesis and human judges to classify whistle types and quantify similarity between types. Contrary to recent studies that emphasize shared whistles, overall whistle sharing between isolated individuals was low (25%) and a simple upsweep did not account for the most common whistle type in half of the animals. Some species of birds, bats, and primates with stable social groups use vocal learning to converge over time to one common group distinctive call type. We examined whistle similarity between adult male dolphins that are partners in a close social alliance in order to test whether vocal learning may enable a similar vocal convergence. Whistle similarity was rated very high between partners and low between non-partners by both the quantitative technique and human observers. This suggests that as in songbirds and some other mammals, adult male bottlenose dolphins may use vocal learning to converge on similar whistles as they develop affiliative social relationships.Communicated by G. Wilkinson 相似文献
53.
The ability of many animals and insects to track a plume to its source is a particularly impressive feat when the fluid dynamics is considered. Inspired by this observation this research seeks to identify the information in a passive scalar plume suitable for developing robust and efficient plume tracing algorithms. The subject of this study is a scalar plume emanating from a point source in a turbulent boundary layer which has been modeled in a laboratory facility built specifically for this purpose. A coupled PIV-LIF technique is used to measure the velocity and scalar field in a time resolved fashion. This data set is analyzed and the convergence rates of five single-point statistics, suitable as kernels of plume tracing algorithms, are investigated. The experimental data shows that the scalar fluctuations over long downstream distances from the source are characterized by filamentary structures that lead to relatively slow convergence rates for any statistic that is based on mean concentrations. The scalar intermittency, however, converges rapidly toward its true value, in fact converging to a testable hypothesis for source location direction faster than the time scale of the larger scale plume meander. 相似文献
54.
北京及华北平原边界层大气中污染物的汇聚系统--边界层输送汇 总被引:35,自引:4,他引:35
由地面、3个大气压风带(1000,925,850hPa)、气压场、温湿廓线、能见度、暖湿平流以及激光雷达,航测分析,提出太行山山前、燕山山前输送汇。输送汇及其摆动常造成华北平原及北京地区区域大气污染物汇聚,是形成重污染区的主要形式。输送汇配置各类风向风带区,冬秋季节多为区域性短而浅的边界层输送风带,夏季多为天气尺度型的、远而厚的边界层输送风带。弱气压场或均压场背景下地方性山风及山前串状城市热岛群形成的热力性、动力性低压环流,是输送汇形成的主要原因。 相似文献
55.
旅游产业与文化产业融合发展研究 总被引:8,自引:1,他引:8
旅游产业与文化产业的融合是产业发展的必然趋势和要求。在回顾产业融合理论研究的基础上,对旅游产业与文化产业的产业边界做出界定,并构建了两大产业的互动融合机制;然后从价值链的角度分析了旅游产业与文化产业融合的过程,并从技术、产品、企业、市场4个层面对两大产业的融合过程进行了解释;最后提出了通过体制观念整合引导市场整合,进而促进资源整合的产业融合发展路径。 相似文献
56.
Kwon-Bin Son 《国际发展与全球生态学杂志》2016,23(2):154-162
The technology convergence integrating multiple devices into a single one is now a distinct trend in electronic industry. This trend can lead to a decrease in the use of rare and toxic heavy metals due to resource sharing, or an increase due to the application of new and auxiliary technology. This study investigates the effect of technology convergence for tablet PC on hazardous waste, resource depletion, and toxicity potentials from heavy metals in electronic devices, considering how many single devices (i.e., netbook computer, electronic dictionary, mp3 player, digital camera, cell phone, and vehicle GPS system) can be displaced by a tablet PC depending on users. The hazardous waste potential from heavy metals is examined with existing U.S. federal and California state regulations, and the resource depletion and toxicity potentials from heavy metals are evaluated based on life cycle impact assessments. The potentials of a specific tablet PC are compared to the total of those of displaced single products. Overall, the tablet PC has lower hazardous waste, resource depletion, and toxicity potentials from heavy metals. However, in case the tablet PC displaces only two or three single devices, it requires more gold, molybdenum, and vanadium. Therefore, technology convergence should take into account materials consumption and user behavior to develop more sustainable products. 相似文献
57.
58.
长江中下游粮食主产区耕地利用生态效率区域差异与空间收敛 总被引:4,自引:0,他引:4
基于耕地利用生态效率内涵构建其评价指标体系,并运用SBM-Undesirable模型、核密度估计法及空间收敛模型,对长江中下游粮食主产区71个市(州)耕地利用生态效率区域差异及收敛态势定量刻画。结果表明:(1)2007—2018年长江中下游粮食主产区耕地利用生态效率整体水平中等,各粮食主产区效率差异明显,效率损失主要源于投入冗余所带来的投入非效率,其中劳动力投入冗余度最高;(2)时间维度上看,长江中下游粮食主产区整体耕地利用生态效率始终存在两级分化的现象,整体内部差异呈扩大趋势,但逐步趋于稳定,各粮食主产区内部差异演变具有较大分异性;(3)空间维度上看,考虑空间溢出效应的情境下,长江中下游粮食主产区整体存在显著的绝对β收敛,且在科技水平、农户收入水平、灌溉水平及空间溢出效应等因素的共同影响下以1.01%的速度条件收敛,但各粮食主产区收敛态势具有区域差异性。应建立粮食主产区协同机制,因地制宜,分区施策以提升长江中下游粮食主产区耕地利用生态效率水平。 相似文献
59.
In reaction to the growing attention to connecting individual‐level and unit‐level constructs, we first briefly review emergence terminology and theories that address the dynamic process by which a higher‐level phenomenon emerges from lower‐level elements. Next, we review the extant theory and research on emergence and convergence in organization science using an organizing framework that simultaneously considers the content area of lower‐level elements, the emergent factors, and the target of the emergent property. In addition to organizing and bridging current literature on emergence and convergence, gaps of existing research and new directions for future research, including compilation and divergence, are identified. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
60.
Based on the Green Development Indicator System issued by the Chinese government, this study conducted an in-depth evaluation of provincial green development in China, from 2013 to 2016. The findings of the study showed that: (1) significant regional differences existed across provinces in China regarding green development. (2) In terms of changing trends, the overall level of green development exhibited an upward trend during the years covered by our study, with a faster rising rate of development in eastern and central regions of China than in western ones. (3) In terms of spatial correlation, the spatial autocorrelation of China’s green development was evident. However, the spatial agglomeration of provincial green development gradually waned during the period in 2013–2016. (4) When it comes to drivers of spatial autocorrelation, the comparatively upward trend in the environmental field served as the main factor that drove green development from agglomeration to balance. (5) In terms of convergence, the tendency showed that less developed regions were about to catch up with leading regions in China in green development, especially as regards the dimensions of ecological protection and resource utilization. 相似文献