全文获取类型
收费全文 | 29453篇 |
免费 | 325篇 |
国内免费 | 221篇 |
专业分类
安全科学 | 831篇 |
废物处理 | 1060篇 |
环保管理 | 4031篇 |
综合类 | 4660篇 |
基础理论 | 8531篇 |
环境理论 | 21篇 |
污染及防治 | 7693篇 |
评价与监测 | 1741篇 |
社会与环境 | 1240篇 |
灾害及防治 | 191篇 |
出版年
2022年 | 172篇 |
2021年 | 179篇 |
2019年 | 214篇 |
2018年 | 387篇 |
2017年 | 378篇 |
2016年 | 554篇 |
2015年 | 489篇 |
2014年 | 677篇 |
2013年 | 2132篇 |
2012年 | 841篇 |
2011年 | 1250篇 |
2010年 | 1025篇 |
2009年 | 1032篇 |
2008年 | 1249篇 |
2007年 | 1329篇 |
2006年 | 1182篇 |
2005年 | 1004篇 |
2004年 | 1003篇 |
2003年 | 937篇 |
2002年 | 936篇 |
2001年 | 1239篇 |
2000年 | 860篇 |
1999年 | 548篇 |
1998年 | 426篇 |
1997年 | 435篇 |
1996年 | 442篇 |
1995年 | 482篇 |
1994年 | 438篇 |
1993年 | 395篇 |
1992年 | 414篇 |
1991年 | 373篇 |
1990年 | 376篇 |
1989年 | 411篇 |
1988年 | 347篇 |
1987年 | 300篇 |
1986年 | 276篇 |
1985年 | 305篇 |
1984年 | 286篇 |
1983年 | 321篇 |
1982年 | 322篇 |
1981年 | 271篇 |
1980年 | 243篇 |
1979年 | 269篇 |
1978年 | 229篇 |
1977年 | 195篇 |
1976年 | 200篇 |
1975年 | 192篇 |
1974年 | 172篇 |
1973年 | 171篇 |
1972年 | 198篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
891.
In the midst of rapidly proliferating engagement efforts around climate adaptation, attention to the design and evaluation of decision support processes and products is warranted. We report on the development and evaluation of a process framework called the Vulnerability, Consequences, and Adaptation Planning Scenarios (VCAPS) process. VCAPS is a systematic approach to integrate local knowledge with scientific understanding by providing opportunities for facilitated, deliberative learning-based activities with local decision makers about climate change vulnerability and adaptation. We introduce the conceptual basis of the process in analytic-deliberation, hazard management, and vulnerability. Our evaluations from eight coastal communities where the approach was applied point to four assets of VCAPS: it promotes synthesis of local and scientific knowledge; it stimulates systems thinking and learning; it facilitates governance by producing action plans with transparent justifications; and it accommodates participant time constraints and preferences. 相似文献
892.
Pasan Samarasin Brian J. Shuter Stephen I. Wright F. Helen Rodd 《Conservation biology》2017,31(1):126-135
Accurate understanding of population connectivity is important to conservation because dispersal can play an important role in population dynamics, microevolution, and assessments of extirpation risk and population rescue. Genetic methods are increasingly used to infer population connectivity because advances in technology have made them more advantageous (e.g., cost effective) relative to ecological methods. Given the reductions in wildlife population connectivity since the Industrial Revolution and more recent drastic reductions from habitat loss, it is important to know the accuracy of and biases in genetic connectivity estimators when connectivity has declined recently. Using simulated data, we investigated the accuracy and bias of 2 common estimators of migration (movement of individuals among populations) rate. We focused on the timing of the connectivity change and the magnitude of that change on the estimates of migration by using a coalescent‐based method (Migrate‐n) and a disequilibrium‐based method (BayesAss). Contrary to expectations, when historically high connectivity had declined recently: (i) both methods over‐estimated recent migration rates; (ii) the coalescent‐based method (Migrate‐n) provided better estimates of recent migration rate than the disequilibrium‐based method (BayesAss); (iii) the coalescent‐based method did not accurately reflect long‐term genetic connectivity. Overall, our results highlight the problems with comparing coalescent and disequilibrium estimates to make inferences about the effects of recent landscape change on genetic connectivity among populations. We found that contrasting these 2 estimates to make inferences about genetic‐connectivity changes over time could lead to inaccurate conclusions. 相似文献
893.
Beverly Z.L. Oh Ana M.M. Sequeira Mark G. Meekan Jonathan L.W. Ruppert Jessica J. Meeuwig 《Conservation biology》2017,31(3):635-645
Fishing and habitat degradation have increased the extinction risk of sharks, and conservation strategies recognize that survival of juveniles is critical for the effective management of shark populations. Despite the rapid expansion of marine protected areas (MPAs) globally, the paucity of shark‐monitoring data on large scales (100s–1000s km) means that the effectiveness of MPAs in halting shark declines remains unclear. Using data collected by baited remote underwater video systems (BRUVS) in northwestern Australia, we developed generalized linear models to elucidate the ecological drivers of habitat suitability for juvenile sharks. We assessed occurrence patterns at the order and species levels. We included all juvenile sharks sampled and the 3 most abundant species sampled separately (grey reef [Carcharhinus amblyrhynchos], sandbar [Carcharhinus plumbeus], and whitetip reef sharks [Triaenodon obesus]). We predicted the occurrence of juvenile sharks across 490,515 km2 of coastal waters and quantified the representation of highly suitable habitats within MPAs. Our species‐level models had higher accuracy (? ≥ 0.69) and deviance explained (≥48%) than our order‐level model (? = 0.36 and deviance explained of 10%). Maps of predicted occurrence revealed different species‐specific patterns of highly suitable habitat. These differences likely reflect different physiological or resource requirements between individual species and validate concerns over the utility of conservation targets based on aggregate species groups as opposed to a species‐focused approach. Highly suitable habitats were poorly represented in MPAs with the most restrictions on extractive activities. This spatial mismatch possibly indicates a lack of explicit conservation targets and information on species distribution during the planning process. Non‐extractive BRUVS provided a useful platform for building the suitability models across large scales to assist conservation planning across multiple maritime jurisdictions, and our approach provides a simple for method for testing the effectiveness of MPAs. 相似文献
894.
895.
Not surprisingly it has been shown that there are higher accident rates and larger magnitudes in Small- and Medium-sized Enterprises (SMEs) if compared with the case of the larger ones. Some studies suggest that SMEs have serious problems aggravated by limited access to human, economic and technological resources. Moreover, it is now acknowledged that methods developed specifically for Large Enterprises (LEs) cannot be simply transferred to smaller enterprises. Although the debate concerning essentially the size of the enterprises and their corresponding accident rates is ongoing, very little attention is paid to the difference between the Micro- (MiEs), the Small- (SEs), and the Medium-sized Enterprises (MEs). Indeed, in most of the cases, SMEs are bundled together and considered as a whole, in opposition to LEs. In some cases SEs and MEs are studied separately, but only the difference in terms of accident rates is highlighted. Instead, important information in terms of performance and organizational, cultural and economic differences between MiEs, SEs and MEs exist. Within the implementation of the E-merging project (financed by the Italian National Institute for Insurance against Occupational Accidents – INAIL), some differences have been identified on the basis of two existing data sources. 相似文献
896.
B. Manos J. Papathanasiou Th. Bournaris K. Voudouris 《Journal of environmental management》2010,91(7):1593-1600
Current international research focuses on topics like sustainable development, regional planning, environmental decision making and implementation, biodiversity conservation plus a number of other relevant issues, especially at times of economic crisis as today. Economic growth and environmental protection can go hand in hand, provided that decision makers develop and use tools and insights targeting in the implementation of successful and robust long term policies. This paper was developed in the framework of a European research project and implements a Multicriteria Mathematical Programming model that optimises the sustainable management of agricultural regions taking in account the available resources (land, labour, capital) and environmental parameters (agrochemicals, water consumption). The model achieves the optimum farm plan in the area combining different criteria to a utility function under a set of constraints and the spatial integration of the vulnerability maps of the regions into the model enables the regional authorities to design policies for the optimal agricultural development and the groundwater protection from the agricultural land uses. Furthermore, the model is used to simulate different scenarios and policies by the local stakeholders, due to changes on different social, economic and environmental parameters. In this way the decision makers can achieve alternative farm plans and agricultural land uses as well as to estimate economic, social and environmental impacts of different policies. The model has been applied to an agricultural region in Northern Greece and proved to be a valuable tool in the implementation of environmental policies and actions, especially in agricultural regions in a delicate balance as the study area. 相似文献
897.
Ângela Guimarães Pereira Frank Raes Tiago De Sousa Pedrosa Paulo Rosa Søsser Brodersen Michael Søgaard Jørgensen Francisco Ferreira Xavier Querol John Rea 《Atmospheric environment (Oxford, England : 1994)》2009,43(33):5423-5432
For more than two decades a number of frameworks for scientific knowledge production are being proposed by science and technology researchers. They all advocate an extended involvement of non-specialists, in particular when it comes to knowledge production applicable to practical societal problems. We look to what extent these new frameworks have taken ground within a particular research community: the ACCENT Network of Excellence which coordinates European atmospheric chemistry and physics research applicable to air pollution and climate change. We did so by stimulating a debate through a “blog”, a survey and in-depth interviews with ACCENT scientists about the interaction between science, policy making and civil society, to which a great deal of ACCENT member contributed in writing or verbally. Most of them had interactions with policy makers and/or the general public, and they generally believe that interactions with spheres other than the scientific are needed. While such interactions give personal insight and satisfaction, they seem to have little impact on the goals and the practice of the scientific work itself. Extended frameworks of science production that go beyond the disciplinary mode seem to emerge at the level of individual scientists, yet they still need to find their way to the level of scientific project management. In this paper we discuss the justifications and barriers to implement a higher degree of extended knowledge integration in applied science projects such as ACCENT. It is felt that the community of atmospheric chemists and physicists is mature for such an implementation and recommendations are given to help and make this happen. 相似文献
898.
Russell M. Wise Graham P. von Maltitz Robert J. Scholes Chris Elphinstone Renee Koen 《Mitigation and Adaptation Strategies for Global Change》2009,14(7):579-604
Minimising the cost of repeatedly estimating C (C) stocks is crucial to the financial viability of projects that seek to sell
C credits. Depending on the price of C, this may imply less or more sampling effort than would be applied for science objectives.
In systems with heterogeneous C pools, such as savannas, this translates into a variable-effort sampling strategy that maximises
the marginal additional C that can be claimed per incremental unit of effort expended. Analysis of a savanna in north-eastern
South Africa indicates relatively modest returns per hectare due to the small C quantities and low sequestration rates. Under
these conditions, areas in excess of 1,000 ha and infrequent sampling frequencies of 5–10 years are required to make such
projects financially viable. For such projects the sample variance, number of samples, cost per sample and establishment costs
have negligible impacts on financial viability. It was also found that the soil-C pool contributes up to three times the net
returns of the aboveground C pool and provides a strong argument to monitor soil C for certification and market trading. The
financial viability estimates, however, do not include the management or opportunity costs incurred in changing the land use.
The economies of scale identified in this study combined with the massive area covered by savannas indicate that these additional
costs can be covered. Further research is recommended to quantify these costs and interrogate the feasibility of large scale
(in excess of 10,000 ha) C-sink projects in savanna systems. 相似文献
899.
Hannah M. Badland Mitch J. Duncan 《Atmospheric environment (Oxford, England : 1994)》2009,43(36):5791-5795
BackgroundThis study examines perceived health effect risks from air pollution during the work-related commute by socio-demographic and travel mode variables.MethodsPopulation-representative survey data were collected by telephone from 745 adults from Queensland, Australia. Variables assessed included socio-demographics, usual work travel mode, commute perceptions, and perceived health effects associated with air pollution during the work-related commute.ResultsApproximately 45% of the sample perceived air pollution negatively affected health outcomes when commuting to/from work, yet only 13% recognised air pollution as a major barrier to walking or cycling to/from work. No relationships existed between usual travel mode to/from work and perceived health risks associated with air pollution. Those higher educated or living in major cities were more likely to recognise air pollution harmed their health during their work-related commute when compared to respective referent categories (p ≤ 0.05).ConclusionsRecognition of health risks from air pollution during the work-related commute was high, and awareness did not differ by travel mode. For the majority, air pollution was not a primary barrier for walking or cycling to/from work. 相似文献
900.