首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3239篇
  免费   21篇
  国内免费   36篇
安全科学   82篇
废物处理   172篇
环保管理   300篇
综合类   552篇
基础理论   681篇
环境理论   2篇
污染及防治   979篇
评价与监测   289篇
社会与环境   217篇
灾害及防治   22篇
  2023年   32篇
  2022年   109篇
  2021年   127篇
  2020年   60篇
  2019年   53篇
  2018年   125篇
  2017年   121篇
  2016年   159篇
  2015年   88篇
  2014年   143篇
  2013年   223篇
  2012年   168篇
  2011年   216篇
  2010年   140篇
  2009年   124篇
  2008年   151篇
  2007年   147篇
  2006年   98篇
  2005年   136篇
  2004年   168篇
  2003年   159篇
  2002年   104篇
  2001年   83篇
  2000年   33篇
  1999年   35篇
  1998年   14篇
  1997年   26篇
  1996年   16篇
  1995年   24篇
  1994年   18篇
  1993年   9篇
  1992年   11篇
  1991年   16篇
  1990年   9篇
  1989年   11篇
  1988年   5篇
  1987年   10篇
  1986年   8篇
  1985年   10篇
  1984年   10篇
  1983年   11篇
  1982年   5篇
  1981年   7篇
  1979年   9篇
  1975年   3篇
  1970年   3篇
  1967年   3篇
  1966年   3篇
  1964年   5篇
  1961年   3篇
排序方式: 共有3296条查询结果,搜索用时 406 毫秒
991.
The inclusion of CO2 capture and storage (CCS) in the Kyoto Protocol's Clean Development Mechanism (CDM) is still subject to controversy and discussion. A myriad of barriers prevents CCS in the CDM. Apart from political barriers, economic, social and procedural barriers play a role. This paper discusses relevant new results on the human capacity, procedural feasibility and economic potential of CCS in the CDM. The conclusions of a capacity building effort in Africa show that awareness and knowledge are low but that capacity building efforts are well received. A reality check on methodologies for hypothetical CCS projects shows that most of the issues can be resolved, and the CDM institutional arrangements can accommodate CCS. A bottom-up estimate of the potential of natural gas processing CCS in the CDM, based on a previously proprietary database from the oil and gas industry, suggests that there is an annual potential of about 174 MtCO2 in 2020 in that sector. Most of that potential can be realized at CER prices between $20 and $30/tCO2 but there is no sign of flooding the CDM market with cheap credits from CCS projects. Despite these results and more open information, the CCS and CDM debate, progress in the negotiations on CCS in the CDM is slow and there is no clear view on a solution.  相似文献   
992.
Emerging water contaminants derived from unleaded gasoline such as methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME), are in need of effective bioremediation technologies for restoring water resources. In order to design the conditions of a future groundwater bioremediating biofilter, this work assesses the potential use of Acinetobacter calcoaceticus M10, Rhodococcus ruber E10 and Gordonia amicalis T3 for the removal of MTBE, ETBE and TAME in consortia or as individual strains. Biofilm formation on an inert polyethylene support material was assessed with scanning electron microscopy, and consortia were also analysed with fluorescent in situ hybridisation to examine the relation between the strains. A. calcoaceticus M10 was the best coloniser, followed by G. amicalis T3, however, biofilm formation of pair consortia favoured consortium M10-E10 both in formation and activity. However, degradation batch studies determined that neither consortium exhibited higher degradation than individual strain degradation. The physiological state of the three strains was also determined through flow cytometry using propidium iodide and 3′-dihexylocarbocyanine iodide thus gathering information on their viability and activity with the three oxygenates since previous microbial counts revealed slow growth. Strain E10 was observed to have the highest physiological activity in the presence of MTBE, and strain M10 activity with TAME was only maintained for 24 h, thus we believe that biotransformation of MTBE occurs within the active periods established by the cytometry analyses. Viable cell counts and oxygenate removal were determined in the presence of the metabolites tert-butyl alcohol (TBA) and tert-amyl alcohol (TAA), resulting in TBA biotransformation by M10 and E10, and TAA by M10. Our results show that A. calcoaceticus M10 and the consortium M10-E10 could be adequate inocula in MTBE and TAME bioremediating technologies.  相似文献   
993.
994.
995.
Sources of phthalates other than Polyvinyl chloride (PVC) related products are scarcely documented in Mexico. The objective of our study was to explore the association between urinary levels of nine phthalate metabolites and the use of personal care products. Subjects included 108 women who participated as controls in an ongoing population-based case-control study of environmental factors and genetic susceptibility to breast cancer in northern Mexico. Direct interviews were performed to inquire about sociodemographic characteristics, reproductive history, use of personal care products, and diet. Phthalate metabolites measured in urine by high performance liquid chromatography-isotope dilution tandem mass spectrometry were monoethyl phthalate (MEP), monobenzyl phthalate (MBzP), mono-n-butyl phthalate (MBP), mono-isobutyl phthalate (MiBP), mono-3-carboxypropyl phthalate (MCPP) as well as mono-2-ethylhexyl phthalate (MEHP), mono-2-ethyl-5-oxohexyl phthalate (MEOHP), mono-2-ethyl-5-hydroxyhexyl phthalate (MEHHP), mono-2-ethyl-5-carboxypentyl phthalate (MECPP) that are metabolites of di-ethylhexyl phthalate (DEHP). Detectable urinary concentrations of phthalate metabolites varied from 75% (MEHP) to 100% (MEP, MBP, MEOHP, MEHHP and MECPP). Medians of urinary concentrations of some phthalate metabolites were significantly higher among users of the following personal care products compared to nonusers: body lotion (MEHHP, MECPP and sum of DEHP metabolites (ΣDEHP)), deodorant (MEHP and ΣDEHP), perfume (MiBP), anti-aging facial cream (MEP, MBP and MCPP) and bottled water (MCPP, MEHHP and MEOHP). Urinary concentrations of MEP showed a positive relationship with the number of personal care products used. Our results suggest that the use of some personal care products contributes to phthalate body burden that deserves attention due to its potential health impact.  相似文献   
996.
997.
Setaria parviflora (Poir.) Kerguélen and Paspalum urvillei Steudel are grasses that grow naturally in a soil with high iron contents. This study aimed to characterize morphoanatomically and histochemically the iron phytotoxicity on leaves and evaluate the phytoextraction potential of these grasses. Saplings were cultivated in hydroponic solution with and without excess Fe-EDTA. Regarding measurements taken on leaves, reduction was observed among treatments of Fe-EDTA on height values of abaxial epidermis and bundle sheath in both species. As for iron histolocalization, stronger reaction was observed in leaves of S. parviflora, in comparison with P. urvillei. Anatomical damage, such as protoplast retraction, irregular xylem, changes in cell volume, and cell collapse, and visual symptoms, like leaf bronzing, chlorosis, and necrosis, were similar in both species when exposed to excess iron; however, P. urvillei showed more severe damage. This species accumulated more iron in shoots than S. parviflora and therefore is more favorable for use in phytoextraction. The root system of both species accumulated higher iron concentrations in relation to shoots.  相似文献   
998.
The biophysical features of small islands (SI) distinguish them from other territories; isolation, small size and several anthropogenic pressures reduce the resilience of ecosystems and increase their vulnerability to global changes. Many SI have a shortage of infrastructures, institutions and technical/financial resources that hinder planning and require different integrated solutions. In Portugal, the National Ecological Reserve (NER) is legally binding for spatial planning instruments. It aims to defend natural values and areas of ecological value, or sensibility, or susceptible to natural hazards. However, the criteria for the design of NER are strictly set for mainland territory, not taking into account specific features of small islands. A case study of the Azores Archipelago is used to demonstrate that spatial planning instruments should be adapted to island contexts. Such adaptation will increase the effectiveness of their implementation in relation to the protection of natural resources, stability of biophysical structures and prevention of natural hazards. Observing the main differences between mainland and the Azores Archipelago it is possible to define a methodological transposition of the NER aims and goals into an island context. This approach is an answer to the constraints in effective adaptation of spatial planning instruments for islands.  相似文献   
999.
1000.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号