全文获取类型
收费全文 | 33273篇 |
免费 | 3203篇 |
国内免费 | 5561篇 |
专业分类
安全科学 | 3690篇 |
废物处理 | 894篇 |
环保管理 | 3760篇 |
综合类 | 16660篇 |
基础理论 | 6987篇 |
环境理论 | 4篇 |
污染及防治 | 4794篇 |
评价与监测 | 2100篇 |
社会与环境 | 2202篇 |
灾害及防治 | 946篇 |
出版年
2024年 | 192篇 |
2023年 | 537篇 |
2022年 | 1358篇 |
2021年 | 1368篇 |
2020年 | 1721篇 |
2019年 | 1199篇 |
2018年 | 1129篇 |
2017年 | 1214篇 |
2016年 | 1244篇 |
2015年 | 1385篇 |
2014年 | 1401篇 |
2013年 | 2581篇 |
2012年 | 2090篇 |
2011年 | 2222篇 |
2010年 | 1974篇 |
2009年 | 1952篇 |
2008年 | 1932篇 |
2007年 | 1964篇 |
2006年 | 1999篇 |
2005年 | 1469篇 |
2004年 | 1242篇 |
2003年 | 971篇 |
2002年 | 859篇 |
2001年 | 1048篇 |
2000年 | 745篇 |
1999年 | 425篇 |
1998年 | 269篇 |
1997年 | 233篇 |
1996年 | 246篇 |
1995年 | 264篇 |
1994年 | 282篇 |
1993年 | 220篇 |
1992年 | 265篇 |
1991年 | 222篇 |
1990年 | 254篇 |
1989年 | 238篇 |
1988年 | 193篇 |
1987年 | 173篇 |
1986年 | 158篇 |
1985年 | 167篇 |
1984年 | 192篇 |
1983年 | 180篇 |
1982年 | 185篇 |
1981年 | 179篇 |
1980年 | 137篇 |
1979年 | 153篇 |
1978年 | 131篇 |
1977年 | 117篇 |
1975年 | 118篇 |
1972年 | 133篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
1.
Kalan Mohammad Ebrahimi Ghobadi Hassan Taleb Ziyad Ben Adham Davoud Cobb Caroline O Ward Kenneth D Behaleh Raed Fazlzadeh Mehdi 《Environmental science and pollution research international》2021,28(30):40346-40354
Environmental Science and Pollution Research - There is mixed evidence surrounding the relationship between tobacco use and COVID-19 infection/progression. The current study investigates beliefs... 相似文献
2.
Babut Marc Marchand Philippe Venisseau Anaïs Veyrand Bruno Ferrari Benoit J. D. 《Environmental science and pollution research international》2021,28(7):7766-7773
Environmental Science and Pollution Research - Legacy (i.e., polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD)) and alternative halogenated flame retardants (HFRs) were... 相似文献
3.
有机固废中碳、磷、硫及重金属等元素赋存形态是决定其环境行为、反应活性及资源化再利用的关键因素.同步辐射光谱技术可以在分子水平、微纳米尺度原位表征有机固废中碳、磷、硫、重金属等元素赋存形态、结合位点、微观结构,为深入阐明有机固废环境行为、反应机制提供直接的证据.概述了X射线吸收光谱、微束X射线荧光光谱等同步辐射光谱技术在有机固废污染控制与资源化研究的中应用进展,并对同步辐射光谱技术在该领域应用前景和发展趋势进行了展望,以期为有机固废资源化再利用及其污染控制等研究提供参考. 相似文献
4.
简要叙述了电捕焦油器开工以来存在的问题,对电捕捕焦油器不能安全稳定运行的原因进行了分析,并采取改进措施。实践证明,改进工艺技术合理,方法可行,电捕焦油器运行效果达到指标要求。 相似文献
5.
6.
Peter Wimmer Michael Düring Henri Chajmowicz Fredrik Granum Julian King Harald Kolk 《Traffic injury prevention》2019,20(4):S139-S145
AbstractObjective: With the overall goal to harmonize prospective effectiveness assessment of active safety systems, the specific objective of this study is to identify and evaluate sources of variation in virtual precrash simulations and to suggest topics for harmonization resulting in increased comparability and thus trustworthiness of virtual simulation-based prospective effectiveness assessment.Methods: A round-robin assessment of the effectiveness of advanced driver assistance systems was performed using an array of state-of-the-art virtual simulation tools on a set of standard test cases. The results were analyzed to examine reasons for deviations in order to identify and assess aspects that need to be harmonized and standardized. Deviations between results calculated by independent engineering teams using their own tools should be minimized if the research question is precisely formulated regarding input data, models, and postprocessing steps.Results: Two groups of sources of variations were identified; one group (mostly related to the implementation of the system under test) can be eliminated by using a more accurately formulated research question, whereas the other group highlights further harmonization needs because it addresses specific differences in simulation tool setups. Time-to-collision calculations, vehicle dynamics, especially braking behavior, and hit-point position specification were found to be the main sources of variation.Conclusions: The study identified variations that can arise from the use of different simulation setups in assessment of the effectiveness of active safety systems. The research presented is a first of its kind and provides significant input to the overall goal of harmonization by identifying specific items for standardization. Future activities aim at further specification of methods for prospective assessments of the effectiveness of active safety, which will enhance comparability and trustworthiness in this kind of studies and thus contribute to increased traffic safety. 相似文献
7.
Tibor Hartel Ben C. Scheele Abi Tamim Vanak Laurențiu Rozylowicz John D. C. Linnell Euan G. Ritchie 《Conservation biology》2019,33(6):1256-1265
Achieving coexistence between large carnivores and humans in human-dominated landscapes (HDLs) is a key challenge for societies globally. This challenge cannot be adequately met with the current sectoral approaches to HDL governance and an academic community largely dominated by disciplinary sectors. Academia (universities and other research institutions and organizations) should take a more active role in embracing societal challenges around conservation of large carnivores in HDLs by facilitating cross-sectoral cooperation to mainstream coexistence of humans and large carnivores. Drawing on lessons from populated regions of Europe, Asia, and South America with substantial densities of large carnivores, we suggest academia should better embrace the principles and methods of sustainability sciences and create institutional spaces for the implementation of transdisciplinary curricula and projects; reflect on research approaches (i.e., disciplinary, interdisciplinary, or transdisciplinary) they apply and how their outcomes could aid leveraging institutional transformations for mainstreaming; and engage with various institutions and stakeholder groups to create novel institutional structures that can respond to multiple challenges of HDL management and human–large carnivore coexistence. Success in mainstreaming this coexistence in HDL will rest on the ability to think and act cooperatively. Such a conservation achievement, if realized, stands to have far-reaching benefits for people and biodiversity. 相似文献
8.
Fishing‐gear restrictions and biomass gains for coral reef fishes in marine protected areas 下载免费PDF全文
Stuart J. Campbell Graham J. Edgar Rick D. Stuart‐Smith German Soler Amanda E. Bates 《Conservation biology》2018,32(2):401-410
Considerable empirical evidence supports recovery of reef fish populations with fishery closures. In countries where full exclusion of people from fishing may be perceived as inequitable, fishing‐gear restrictions on nonselective and destructive gears may offer socially relevant management alternatives to build recovery of fish biomass. Even so, few researchers have statistically compared the responses of tropical reef fisheries to alternative management strategies. We tested for the effects of fishery closures and fishing gear restrictions on tropical reef fish biomass at the community and family level. We conducted 1,396 underwater surveys at 617 unique sites across a spatial hierarchy within 22 global marine ecoregions that represented 5 realms. We compared total biomass across local fish assemblages and among 20 families of reef fishes inside marine protected areas (MPAs) with different fishing restrictions: no‐take, hook‐and‐line fishing only, several fishing gears allowed, and sites open to all fishing gears. We included a further category representing remote sites, where fishing pressure is low. As expected, full fishery closures, (i.e., no‐take zones) most benefited community‐ and family‐level fish biomass in comparison with restrictions on fishing gears and openly fished sites. Although biomass responses to fishery closures were highly variable across families, some fishery targets (e.g., Carcharhinidae and Lutjanidae) responded positively to multiple restrictions on fishing gears (i.e., where gears other than hook and line were not permitted). Remoteness also positively affected the response of community‐level fish biomass and many fish families. Our findings provide strong support for the role of fishing restrictions in building recovery of fish biomass and indicate important interactions among fishing‐gear types that affect biomass of a diverse set of reef fish families. 相似文献
9.
M. Kansanga P. Andersen D. Kpienbaareh S. Mason-Renton K. Atuoye Y. Sano 《国际发展与全球生态学杂志》2019,26(1):11-24
Following the renewed effort at achieving a new green revolution for Africa, emphasis has been placed on modernizing smallholder agriculture through the deployment of improved inputs especially mechanized technologies. In Ghana, the government has in the last decade emphasized the provision of subsidized mechanized ploughing services to farmers alongside a rapidly growing private sector tractor service market. While mechanized technology adoption rates have increased rapidly, the deployment of these technologies has been without critical analysis of the impacts on production patterns and local agrarian systems. This paper examines the distributional impacts of agriculture mechanization on cropping patterns and farm sizes of smallholder farmers in northern Ghana using Geographic Information Systems (GIS) techniques, and semi-structured interviews with smallholder farmers (n=60). Specifically, comparative analysis of the field sizes and cropping patterns of participant farmers prior to and after the adoption of mechanized technologies was conducted. In-depth interviews were used to contextualize the experiences of smallholder farmers toward understanding how mechanization may be impacting traditional agriculture. Our findings reveal a mechanization paradox in which farm sizes are expanding, while cropping patterns are shifting away from traditional staple crops (pearl millet and sorghum bicolor) to market-oriented crops (maize, rice and groundnuts). This transition we argue, has adverse implications on the cultural dimension of food security, the organization of social life, and climate change adaptation. We recommend a retooling of the current agricultural policy focus to ensure context sensitivity for a more robust battle against food insecurity. 相似文献
10.
为探究我国重特大安全生产事故特征,选取2005-2019年国内852起重特大事故作为研究对象,基于Python编程语言针对重特大事故发生的年份、季度、月份、工作日与非工作日、地域特征进行分析.结果表明:2005-2019年,国内重特大安全生产事故起数和死亡人数均在不断下降;第四季度发生重特大事故最多,而第三季度平均每起事故造成的死亡人数最多;重特大事故数量和死亡人数随月份显示出反复波动的趋势,均呈现3个"^",形;工作日期间发生的重特大事故数量最多,非工作日平均事故率最大;国庆节是重特大事故发生最多的节假日;贵州、湖南、山西、云南、河南等省份"十四五"期间需要重点加强安全和应急管理. 相似文献