全文获取类型
收费全文 | 13344篇 |
免费 | 123篇 |
国内免费 | 58篇 |
专业分类
安全科学 | 362篇 |
废物处理 | 344篇 |
环保管理 | 2001篇 |
综合类 | 3368篇 |
基础理论 | 3122篇 |
环境理论 | 6篇 |
污染及防治 | 3314篇 |
评价与监测 | 580篇 |
社会与环境 | 363篇 |
灾害及防治 | 65篇 |
出版年
2018年 | 123篇 |
2017年 | 128篇 |
2016年 | 187篇 |
2015年 | 163篇 |
2014年 | 205篇 |
2013年 | 962篇 |
2012年 | 308篇 |
2011年 | 438篇 |
2010年 | 311篇 |
2009年 | 410篇 |
2008年 | 454篇 |
2007年 | 483篇 |
2006年 | 436篇 |
2005年 | 335篇 |
2004年 | 349篇 |
2003年 | 386篇 |
2002年 | 325篇 |
2001年 | 468篇 |
2000年 | 330篇 |
1999年 | 219篇 |
1998年 | 156篇 |
1997年 | 150篇 |
1996年 | 184篇 |
1995年 | 181篇 |
1994年 | 204篇 |
1993年 | 184篇 |
1992年 | 189篇 |
1991年 | 182篇 |
1990年 | 209篇 |
1989年 | 194篇 |
1988年 | 166篇 |
1987年 | 164篇 |
1986年 | 148篇 |
1985年 | 165篇 |
1984年 | 148篇 |
1983年 | 159篇 |
1982年 | 160篇 |
1981年 | 163篇 |
1980年 | 149篇 |
1979年 | 145篇 |
1978年 | 142篇 |
1977年 | 129篇 |
1976年 | 136篇 |
1975年 | 114篇 |
1974年 | 142篇 |
1973年 | 125篇 |
1972年 | 125篇 |
1971年 | 105篇 |
1970年 | 106篇 |
1967年 | 116篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Planning in sustainable development is believed to be an important element in allowing higher education institutions to set their goals and to commit themselves towards undertaking concrete actions and measures at all levels in order to implement sustainability. Yet, there is a paucity of research that has looked at the extent to which planning can support institutions of higher education to assess their performances and to determine whether the set aims have been met. This research gap needs to be met to allow a better understanding of how planning can help to promote the integration of the three components of sustainable development – economic development, social development and environmental protection in higher education. This paper explores the challenges for planning the sustainable development in higher education, also outlining the potentials lessons learned that could assist in improving Education for Sustainable Development efforts in Higher Education Institutions. Among its main results are the fact that many universities wish to pursue sustainable development, but their efforts are hindered by lack of institutional support and planning and limited emphasis on approaches, such as problem-based learning. The universities that are engaged in the field have to face many problems, varying from limited resources to lack of trained staff. As a result, integrated approaches to sustainability become difficult to implement. Finally, the paper has identified the fact that many opportunities offered mainstream developments, such as the UN Declaration ‘The World we Want’ or the UN Sustainable Development Goals are not being put to full use. 相似文献
992.
The urban ecological risk incurred during the processes of urbanization has been constantly accumulating, creating a severe challenge for China to achieve sustainable urban development. At present, research on systematic evaluation of urban ecological risks is still inadequate, especially at an urban ecosystem level. In this special issue, we use Xiamen City as an example to identify the sources and receptors of urban ecological risks, to develop a methodology system of urban ecological risk assessment, and to propose a method for the management of urban ecological risks. This special issue contains 11 research articles resulting from a comprehensive research project funded by China’s National Natural Science Foundation. The innovations reported in this special issue include a framework of urban ecological risk assessment and a standardized procedure for carrying out urban ecological risk assessment using multiple stressors and endpoints. 相似文献
993.
Francesca Pilotto Jonathan D. Tonkin Kathrin Januschke Armin W. Lorenz Jonas Jourdan Andrea Sundermann Daniel Hering Stefan Stoll Peter Haase 《Conservation biology》2019,33(1):132-141
Although experiences with ecological restoration continue to accumulate, the effectiveness of restoration for biota remains debated. We complemented a traditional taxonomic analysis approach with information on 56 species traits to uncover the responses of 3 aquatic (fish, macroinvertebrates, macrophytes) and 2 terrestrial (carabid beetles, floodplain vegetation) biotic groups to 43 hydromorphological river restoration projects in Germany. All taxonomic groups responded positively to restoration, as shown by increased taxonomic richness (10–164%) and trait diversity (habitat, dispersal and mobility, size, form, life history, and feeding groups) (15–120%). Responses, however, were stronger for terrestrial than aquatic biota, and, contrary to our expectation, taxonomic responses were stronger than those of traits. Nevertheless, trait analysis provided mechanistic insights into the drivers of community change following restoration. Trait analysis for terrestrial biota indicated restoration success was likely enhanced by lateral connectivity and reestablishment of dynamic processes in the floodplain. The weaker response of aquatic biota suggests recovery was hindered by the persistence of stressors in the aquatic environment, such as degraded water quality, dispersal constraints, and insufficient hydromorphological change. Therefore, river restoration requires combined local- and regional-scale approaches to maximize the response of both aquatic and terrestrial organisms. Due to the contrasting responses of aquatic and terrestrial biota, the planning and assessment of river restoration outcomes should consider effects on both components of riverine landscapes. 相似文献
994.
995.
R. Hickisch T. Hodgetts P. J. Johnson C. Sillero-Zubiri K. Tockner D.W. Macdonald 《Conservation biology》2019,33(5):1151-1163
Conservation planners need reliable information on spatial patterns of biodiversity. However, existing data sets are skewed because some ecosystems, taxa, and locations are underrepresented. We determined how many articles have been published in recent decades on the biodiversity of different countries and their constituent provinces. We searched the Web of Science catalogues Science Citation Index (SCI) and Social Science Citation Index (SSCI) for biodiversity-related articles published from 1993 to 2016 that included country and province names. We combined data on research publication frequency with other provincial-scale factors hypothesized to affect the likelihood of research activity (i.e., economic development, human presence, infrastructure, and remoteness). Areas that appeared understudied relative to the biodiversity expected based on site climate likely have been inaccessible to researchers for reasons, notably armed conflict. Geographic publication bias is of most concern in the most remote areas of sub-Saharan Africa and South America. Our provincial-scale model may help compensate for publication biases in conservation planning by revealing the spatial extent of research needs and the low cost of redoing this analysis annually. 相似文献
996.
Humanitarian governance is usually understood according to the classic, Dunantist paradigm that accords central importance to international humanitarian agencies. However, this is increasingly paralleled by ‘resilience humanitarianism’ that focuses, among other things, on including national actors in humanitarian governance. This article views humanitarian governance as emerging through interactions between authorities, implementing agencies and communities. It is based on interactive ethnography in five countries by Partners for Resilience (PfR). Using the Theory of Change (ToC) tool, it analyses the various interpretations and priorities of actors involved in humanitarian problems, solutions and programme governance. For example, PfR had a ‘software’ focus, aiming to unlock communities’ potential for resilience, whereas communities and authorities preferred to receive tangible ‘hardware’ support. The findings highlight the crucial role of local authorities in shaping humanitarian aid. This is especially pertinent in view of the international agenda to localise aid, which requires the understanding and support of national actors in order to responsibly protect the vulnerable. 相似文献
997.
Queena K. Qian Winky K.O. Ho J. Jorge Ochoa Edwin H.W. Chan 《Sustainable Development》2019,27(4):657-668
The aging population is one of the demographic changes in the 21st century. World Health Organization defines an age‐friendly city as a place that has an “inclusive and accessible urban environment that promotes active aging.” It receives considerable attention in the field of gerontology and contains important aspects of sustainable urban development. Unfortunately, there have not much research that addresses the relationship between aging‐friendly and sustainability. There is a need to modify the market mechanism to achieve environmental objectives while striking a balance between social and economic considerations. This paper aims to empirically examine the integrated relationships between the dense urban environment and the social and emotional needs of the elderly in the Hong Kong context. The on‐street survey was conducted in eight districts in Hong Kong to collect the opinions about aging‐friendly criteria and sustainability indicators. It utilizes principal component analysis and multiple regression technique to unveil the mask of their intrinsic relationship. The empirical results suggest how the aging‐friendly factors have impacted the economic, environmental, and social sustainability to a certain extent. Notably, two key findings were revealed from the empirical results. (a) “Outdoor Spaces” is consistently found not to be a planning factor that can enhance three types of sustainability, irrespective of the age groups in Hong Kong; (b) “Community Support and Health Services” is regarded as a significant factor, with the exception of economic sustainability (age group ≤60). 相似文献
998.
Advances in information and communication technologies enable the public to contribute to emergency response. For instance, reporting systems set up during recent disasters allowed affected people to submit testimonies about conditions on the ground. In addition, the public has analysed data and helped to mobilise and deliver relief resources. To plan intentionally for an integrative emergency response system in the networked age, this research explores two subject areas: (i) the organisational and technical determinants of relationships forged between formal organisations and participatory online groups established by the public; and (ii) the consequences of the outcomes generated by these relationships. Four in‐depth case studies were selected for the analysis, which revealed that resource dependence, shared understanding, and the use of certain types of information technology influence the formation of such relationships. Furthermore, healthy collaborative relationships increase the chances of desirable results, including inter‐organisational alignment and minimal long‐term harm owing to a disaster. 相似文献
999.
Both phytophagous and parasitic insects deposit oviposition-marking pheromones (OMPs) following oviposition that function
to inform conspecifics of a previously utilized host of reduced suitability. The blueberry maggot fly, Rhagoletis mendax Curran (Diptera: Tephritidae), deposits eggs individually into blueberries and then marks the fruit surface with an OMP which
reduces acceptance of fruit for oviposition by conspecifics. Diachasma alloeum (Muesebeck) (Hymenoptera: Braconidae) is a parasitic wasp attacking larval R. mendax which also deposits an OMP, signaling conspecifics of a wasp-occupied host. Behavioral studies were conducted testing the
hypothesis that the OMP of the parasitic wasp modifies the oviposition behavior of its host fly. In this study, we show that
the OMP of D. alloeum is recognized by R. mendax, and female flies will reject wasp-marked fruit for oviposition. Thus, we present a rare demonstration of pheromonal recognition
between animals occupying different taxonomic orders and trophic levels. This chemical eavesdropping may enhance the ability
of the fly to avoid fruit unsuitable for larval development. 相似文献
1000.
S. B. Dorofeev M. S. Kuznetsov V. I. Alekseev A. A. Efimenko W. Breitung 《Journal of Loss Prevention in the Process Industries》2001,14(6):583-589
Results of experiments and data analysis on turbulent flame propagation in obstructed channels are presented. The data cover a wide range of mixtures: H2/air, H2/air/steam (from lean to rich) at normal and elevated initial temperatures (from 298 to 650 K) and pressures (from 1 to 3 bar); and stoichiometric H2/O2 mixtures diluted with N2, Ar, He and CO2 at normal initial conditions. The dataset chosen also covers a wide range of scales exceeding two orders of magnitude. It is shown that basic flame parameters, such as mixture expansion ratio σ, Zeldovich number β and Lewis number Le, can be used to estimate a priori a potential for effective flame acceleration for a given mixture. Critical conditions for effective flame acceleration are suggested in the form of correlations of critical expansion ratio σ* versus dimensionless effective activation energy. On this basis, limits for effective flame acceleration for hydrogen combustibles can be estimated. Uncertainties in determination of critical σ* values are discussed. 相似文献