全文获取类型
收费全文 | 1487篇 |
免费 | 47篇 |
国内免费 | 23篇 |
专业分类
安全科学 | 61篇 |
废物处理 | 65篇 |
环保管理 | 323篇 |
综合类 | 125篇 |
基础理论 | 474篇 |
环境理论 | 4篇 |
污染及防治 | 296篇 |
评价与监测 | 106篇 |
社会与环境 | 83篇 |
灾害及防治 | 20篇 |
出版年
2023年 | 11篇 |
2022年 | 25篇 |
2021年 | 33篇 |
2020年 | 26篇 |
2019年 | 30篇 |
2018年 | 38篇 |
2017年 | 51篇 |
2016年 | 54篇 |
2015年 | 51篇 |
2014年 | 53篇 |
2013年 | 128篇 |
2012年 | 71篇 |
2011年 | 120篇 |
2010年 | 71篇 |
2009年 | 89篇 |
2008年 | 104篇 |
2007年 | 94篇 |
2006年 | 77篇 |
2005年 | 56篇 |
2004年 | 55篇 |
2003年 | 52篇 |
2002年 | 33篇 |
2001年 | 15篇 |
2000年 | 14篇 |
1999年 | 19篇 |
1998年 | 15篇 |
1997年 | 14篇 |
1996年 | 18篇 |
1995年 | 13篇 |
1994年 | 18篇 |
1993年 | 13篇 |
1992年 | 15篇 |
1991年 | 8篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1978年 | 4篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1973年 | 2篇 |
1959年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有1557条查询结果,搜索用时 593 毫秒
781.
This paper describes the progress that local authorities in England and Wales are making in adapting to the threat of climate change and taking action to reduce greenhouse gas emissions. The responses from surveys of local authorities in England and Wales carried out in 2000 (IDeA, Reducing Greenhouse Gas Emissions: survey of activities and initiatives by local authorities. (Questionnaire and results) Improvement and Development Agency, 2000) and 2002 (Allman et al., Climate Change: a survey of local authorities, Local Government Association, 2002) were compared. Progress in implementing the International Council for Local Environmental Initiatives (ICLEI) five-step methodology (ICLEI, Local Government Implementation of Climate Protection—report to the United Nations, International Council for Local Environmental Initiatives, 1997) was used to identify the 'successful' local authorities. The barriers faced by these authorities were then compared with those faced by the remaining local authorities.
Most local authorities are not making substantial progress. However, a small number have successfully prepared greenhouse gas emissions inventories, developed strategies and implemented adaptation and greenhouse gas reduction measures. These successful authorities have made progress despite the fact that addressing climate change is not a legal requirement.
Their success is due to three key factors. Firstly, they have recognised the secondary benefits of tackling climate change, e.g. potential employment, improved quality of life and reduction in fuel poverty. Secondly, they have the strong political, professional and technical support necessary to champion climate change activities. Finally, they have worked in partnership with utilities, private, public and voluntary groups to raise the finance needed to implement measures both to adapt to climate change and to reduce greenhouse gas emissions. 相似文献
Most local authorities are not making substantial progress. However, a small number have successfully prepared greenhouse gas emissions inventories, developed strategies and implemented adaptation and greenhouse gas reduction measures. These successful authorities have made progress despite the fact that addressing climate change is not a legal requirement.
Their success is due to three key factors. Firstly, they have recognised the secondary benefits of tackling climate change, e.g. potential employment, improved quality of life and reduction in fuel poverty. Secondly, they have the strong political, professional and technical support necessary to champion climate change activities. Finally, they have worked in partnership with utilities, private, public and voluntary groups to raise the finance needed to implement measures both to adapt to climate change and to reduce greenhouse gas emissions. 相似文献
782.
The Bhopal disaster in India in 1984 has compelled manufacturing companies to review their operations in order to minimize their risk exposure. Much study has been done on the subject of risk assessment and in refining safety reviews of plant operations. However, little work has been done to address the broader needs of decision makers in the multinational environment. The corporate headquarters of multinational organizations are concerned with identifying vulnerable areas to assure that appropriate risk-minimization measures are in force or will be taken. But the task of screening global business units for safety prowess is complicated and time consuming. This article takes a step towards simplifying this process by presenting the decisional model developed by the authors. Beginning with an overview of key issues affecting global safety management, the focus shifts to the multinational vulnerability model developed by the authors, which reflects an integration of approaches. The article concludes with a discussion of areas for further research. While the global chemical industry and major incidents therein are used for illustration, the procedures and solutions suggested here are applicable to all manufacturing operations. 相似文献
783.
Charles T. Roman Robert A. Zampella Andrew Z. Jaworski 《Journal of the American Water Resources Association》1985,21(6):1005-1012
Wetland protection regulations and guidelines often require the delineation of precise wetland boundaries on a case-by-case basis. In this study, conducted in the New Jersey Pinelands, an ecological characterization of vegetation composition, soil and hydrologic relationships along upland to wetland Pinus rigida - dominated transittions provided the basis for a multiparameter approach to wetland boundary delineation. The transitional data set was analyzed by direct gradient analysis, cluster analysis and ordination. It is concluded that vegetation composition can be a principal factor in delineating wetland boundaries along natural upland to wetland transitions. However, where distinct vegetation changes are not observed, a feature of our study sites, a multiparameter approach should be used. 相似文献
784.
Our research involves determining how non-invasive electric and magnetic fields influence neuronal growth in vitro. In previous
studies we have shown that pulsed electromagnetic fields (PEMF) as well as direct current (DC) alone stimulate neurite outgrowth
from dorsal root ganglion explants [Sisken et al. 1984; Sisken et al. (Restor Neurol Neurosci 1:303–309, 1990); Greenebaum
et al. (Bioelectromagnetics 17:293–302, 1996)]. A maximum response was obtained when nerve growth factor (NGF) was also present
in the medium. The results of our experiments using static magnetic fields of different strengths are presented below and
indicate that fields of high magnetic strength (450–900 gauss) with added NGF stimulate neurite outgrowth comparable to the
response obtained with PEMF plus NGF. 相似文献
785.
786.
Consequences of organic and non-organic farming practices for field,farm and landscape complexity 总被引:1,自引:0,他引:1
787.
Andrew McDonald Susan Riha Antonio DiTommaso Arthur DeGaetano 《Agriculture, ecosystems & environment》2009,130(3-4):131-140
By the end of the century, climate change projections under a “business-as-usual” emissions scenario suggest a globally averaged warming of 2.4–6.4 °C. If these forecasts are realized, cropping systems are likely to experience significant geographic range transformations among damaging endemic weed species and new vulnerabilities to exotic weed invasions. To anticipate these changes and to devise management strategies for proactively addressing them, it is necessary to characterize the environmental conditions that make specific weed species abundant, competitive, and therefore damaging the production of particular crops (i.e. defining the damage niche). In this study, U.S. maize is used as a model system to explore the implications of climate change on the distribution of damaging agricultural weeds. To accomplish this, we couple ensemble climate change projections of annual temperature and precipitation with survey data of troublesome weed species in maize. At the state scale, space-for-time substitution techniques are used to suggest the potential magnitude of change among damaging weed communities. To explore how the geography of damage for specific species may evolve over the next century, bioclimatic range rules were derived for two weed species that are pervasive in the Northern (Abutilon theophrasti Medicus, ABUTH) and Southern (Sorghum halepense (L.) Pers., SORHA) U.S. Results from both analyses suggest that the composition of damaging weed communities may be fundamentally altered by climate change. In some states, potential changes in the coming decades are commensurate to those possible by the end of the century. Regions such as the Northeastern U.S. may prove particularly vulnerable with emerging climate conditions favoring few weed species of present-day significance. In contrast, regions like the mid-South are likely to experience fewer shifts even with a similar magnitude in climate change. By the end of the century in the U.S. Corn Belt, cold-tolerant species like A. theophrasti may be of minor importance whereas S. halepense, a predominantly Southern U.S. weed species at present, may become common and damaging to maize production with its damage niche advancing 200–600 km north of its present-day distribution. 相似文献
788.
Facial and vocal expressions of emotion have been found in a number of social mammal species and are thought to have evolved
to aid social communication. There has been much debate about whether such signals are culturally inherited or are truly biologically
innate. Evidence for the innateness of such signals can come from cross-cultural studies. Previous studies have identified
a vocalisation (the V4 or ‘excitement’ call) associated with high arousal behaviours in a population of killer whales in British
Columbia, Canada. In this study, we compared recordings from three different socially and reproductively isolated ecotypes
of killer whales, including five vocal clans of one ecotype, each clan having discrete culturally transmitted vocal traditions.
The V4 call was found in recordings of each ecotype and each vocal clan. Nine independent observers reproduced our classification
of the V4 call from each population with high inter-observer agreement. Our results suggest the V4 call may be universal in
Pacific killer whale populations and that transmission of this call is independent of cultural tradition or ecotype. We argue
that such universality is more consistent with an innate vocalisation than one acquired through social learning and may be
linked to its apparent function of motivational expression. 相似文献
789.
Adamatzky A 《Die Naturwissenschaften》2007,94(12):975-980
The Physarum machine is a biological computing device, which employs plasmodium of Physarum polycephalum as an unconventional computing substrate. A reaction–diffusion computer is a chemical computing device that computes by propagating
diffusive or excitation wave fronts. Reaction–diffusion computers, despite being computationally universal machines, are unable
to construct certain classes of proximity graphs without the assistance of an external computing device. I demonstrate that
the problem can be solved if the reaction–diffusion system is enclosed in a membrane with few ‘growth points’, sites guiding
the pattern propagation. Experimental approximation of spanning trees by P. polycephalum slime mold demonstrates the feasibility of the approach. Findings provided advance theory of reaction–diffusion computation
by enriching it with ideas of slime mold computation. 相似文献
790.
Host intra-clutch variation,cuckoo egg matching and egg rejection by great reed warblers 总被引:3,自引:1,他引:2
Prevailing theory predicts that lower levels of intra-clutch variation in host eggs facilitate the detection of brood parasitism.
We assessed egg matching using both human vision and UV-VIS spectrophotometry and then followed the nest fate of great reed
warblers naturally parasitised by European cuckoos. Rejection was predicted by the following three variables: matching between
cuckoo and host eggs on the main chromatic variable defined by principal components analysis of the egg spectra (which has
a strong loading in the UV); the number of host eggs in the nest; and human estimates of intra-clutch variation. The first
variable is not correlated to human estimates of matching, which do not predict rejection. In line with another recent study,
rejection rates were predicted by higher levels of intra-clutch variation in the host eggs, suggesting that higher rather
than lower levels of intra-clutch variation can facilitate the discrimination of cuckoo eggs by hosts. We suggest that the
importance of intra-clutch variation is context dependent, with intra-clutch variation being important when there is good
matching between the host and the cuckoo eggs. Our results also suggest that both spectrometric and human visual assessments
of egg matching and intra-clutch variation are prudent: the former provide the best method of estimating reflectance variation,
whereas the latter include some assessment of patterns of maculation. 相似文献