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   3058篇
  免费   42篇
  国内免费   26篇
安全科学   163篇
废物处理   155篇
环保管理   620篇
综合类   335篇
基础理论   738篇
环境理论   5篇
污染及防治   766篇
评价与监测   217篇
社会与环境   108篇
灾害及防治   19篇
  2023年   26篇
  2022年   37篇
  2021年   26篇
  2020年   21篇
  2019年   32篇
  2018年   66篇
  2017年   68篇
  2016年   91篇
  2015年   59篇
  2014年   85篇
  2013年   283篇
  2012年   143篇
  2011年   180篇
  2010年   121篇
  2009年   122篇
  2008年   154篇
  2007年   190篇
  2006年   153篇
  2005年   106篇
  2004年   106篇
  2003年   118篇
  2002年   94篇
  2001年   70篇
  2000年   49篇
  1999年   52篇
  1998年   39篇
  1997年   43篇
  1996年   43篇
  1995年   41篇
  1994年   42篇
  1993年   34篇
  1992年   39篇
  1991年   26篇
  1990年   29篇
  1989年   19篇
  1988年   13篇
  1987年   20篇
  1986年   25篇
  1985年   17篇
  1984年   19篇
  1983年   28篇
  1982年   28篇
  1981年   25篇
  1980年   19篇
  1979年   16篇
  1977年   11篇
  1976年   9篇
  1975年   9篇
  1974年   10篇
  1971年   11篇
排序方式: 共有3126条查询结果,搜索用时 15 毫秒
111.
Dissipation and decontamination of chlorantraniliprole (Coragen 18.5 SC) in brinjal and okra fruits were studied following field application at single and double doses of 30 and 60 g ai ha?1, and the residues of the insecticide was estimated using LC-MS/MS. Initial residues of chlorantraniliprole at single and double doses on the fruits of brinjal were 0.72 and 1.48 mg kg?1, while on okra fruits, the residues were 0.48 and 0.91 mg kg?1, respectively. The residues reached below detectable level of 0.01 mg kg?1 on the 10th day. Half-life of chlorantraniliprole at 30 and 60 g ai ha?1 on brinjal was 1.58 and 1.80 days with the calculated waiting period of 0.69 and 2.38 days, whereas on okra, the values were 1.60 and 1.70 and 0 and 1.20 days, respectively. The extent of removal of chlorantraniliprole using simple decontaminating techniques at 2 h and 3 days after spraying was 40.99–91.37 % and 29.85–89.12 %, respectively, from brinjal fruits and 47.78–86.10 % and 41.77–86.48 %, respectively, from okra fruits.  相似文献   
112.
The climate change mitigation mechanism Reducing Emissions from Deforestation and Forest Degradation in developing countries (REDD+) is currently being negotiated under the United Nations Framework Convention on Climate Change (UNFCCC). Integrating biodiversity monitoring into REDD+ facilitates compliance with the safeguards stipulated by the UNFCCC to exclude environmental risks. Interviews with actors engaged in REDD+ implementation and biodiversity conservation at the national and sub-national level in Peru (n = 30) and a literature review (n = 58) were conducted to pinpoint constraints and opportunities for monitoring effects of REDD+ management interventions on biodiversity, and to identify relevant biodiversity data and indicators. It was found that particularly sub-national actors, who were frequently involved in REDD+ pilot projects, acknowledge the availability of biodiversity data. Actors at both the national and sub-national levels, however, criticized data gaps and data being scattered across biodiversity research organizations. Most of the literature reviewed (78 %) included indicators on the state of certain biodiversity aspects, especially mammals. Indicators for pressure on biodiversity, impacts on environmental functions, or policy responses to environmental threats were addressed less frequently (31, 21, and 10 %, respectively). Integrating biodiversity concerns in carbon monitoring schemes was considered to have potential, although few specific examples were identified. The involvement of biodiversity research organizations in sub-national REDD+ activities enhances monitoring capacities. It is discussed how improvements in collaboration among actors from the project to the national level could facilitate the evaluation of existing information at the national level. Monitoring changes in ecosystem services may increase the ecological and socioeconomic viability of REDD+.  相似文献   
113.
Vehicles on beaches cause numerous deleterious effects to coastal wildlife. These impacts may, hypothetically, be lessened if drivers act to reduce disturbance. Since it is unknown to what extent such behavior occurs, and whether it can reduce disturbance, we quantified the behavior of drivers who encountered birds on open-coast, sandy beaches in eastern Australia and the consequent bird responses. Drivers of commercial tourist buses never slowed or altered course (“evaded birds”) to avoid disturbing birds; conversely, 34 % of drivers of private cars did evade birds. Drivers of vehicles with fishing rod holders tended (P = 0.09) to evade birds more frequently than non-fishing vehicles. Evasion, when it occurred, was modest, and did not significantly decrease the intensity of bird response or the probability of escapes on the wing. Voluntary behavioral adjustments to alleviate impacts on wildlife may be unworkable, suggesting that other solutions (e.g., beach closures) might be the only effective and feasible way to reduce disturbance to birds on ocean beaches.  相似文献   
114.
The brominated flame retardants (BFRs), pentabromotoluene (PBT), pentabromoethylbenzene (PBEB) and hexabromobenzene (HBB), exhibit physical-chemical properties similar to other persistent organic pollutants, and have been in use as flame retardants for several decades. Data on these BFRs in diverse environmental samples can be found in studies from the 1970s and 1980s, as well as in recent years, though very little in the years in between. Due to a lack of data, the cause for the apparent re-emergence of these BFRs in recent studies is unclear, and could reflect changes in production volumes, accumulation of transformation products from BFR precursors, improved analytical techniques or simply a re-emergence in concern. Very little data are available on their environmentally relevant partitioning properties, which could help to explain the occurrence and fate of these BFRs. In this study we analysed for the presence of HBB, PBT, and PBEB in diverse environmental samples from potential Norwegian BFR source zones. Additionally, environmental partitioning properties of these BFRs as well as brominated benzenes were estimated and validated using experimental data for brominated benzenes. Of the three BFRs, HBB was identified in detectable quantities at most source zones, PBEB only near a metal recycling factory, and PBT only in a few additional locations from where PBEB was detected. Data from this study show that HBB is likely widely distributed, as verified both by chemical analysis and estimated properties. Measured HBB levels in wastewater treatment plants indicate that the treatment practices used in the study locations are not effective at lowering HBB levels, perhaps due to association with low density suspended solids (e.g. microplastics).  相似文献   
115.
ORSANCO and the six Ohio River main stem states have been working to align states' fish consumption advisories (FCAs) to enhance the value of advice issued to the public. To achieve this goal, ORSANCO worked closely with a panel consisting of state and USEPA representatives. The result of this effort is the Ohio River Fish Consumption Advisory Protocol (ORFCAP). The ORFCAP represents a single set of variables agreed upon by the panel that allows for a standardized protocol to create advisory thresholds to which states can defer to issue consumption advice for the Ohio River. The ORFCAP identifies ORSANCO as a clearinghouse for data which will be distributed to the panel for decision making. Other components include identifying primary contaminants of concern (PCBs and mercury) and dividing the river into four reporting units. The protocol was developed to issue FCAs for the protection of sensitive populations using five advisory groupings for PCBs and four for mercury. Specific variables used in the calculation of advisory thresholds such as health protection values, cooking reductions, average meal sizes, etc., were selected by the panel. Lastly, the protocol calls for FCA decisions to be based on analysis of the most recent 10?years of data for each species in each reporting unit to determine size class needs and advisory groupings. Upon pending implementation of the protocol by the main stem states, these decisions will be made annually through a series of discussions involving ORSANCO, the panel, and other appropriate state personnel.  相似文献   
116.
Six trace contaminants (acesulfame (ACE), sucralose (SUC), carbamazepine (CBZ), diatrizoic acid (DTA), 1H-benzotriazole (BTZ) and its 4-methyl analogue (4-TTri)) were traced from wastewater treatment plants (WWTPs) to receiving waters and further to riverbank filtration (RBF) wells to evaluate their prediction power as potential wastewater markers. Furthermore, the persistence of some compounds was investigated in advanced wastewater treatment by soil aquifer treatment (SAT). During wastewater treatment in four conventional activated sludge WWTPs ACE, SUC, and CBZ showed a pronounced stability expressed by stable concentration ratios in influent (in) and effluent (out) (ACE/CBZ: in45, out40; SUC/CBZ: in1.8, out1.7; and ACE/SUC: in24, out24). In a fifth WWTP, additional treatment with powdered activated carbon led to a strong elimination of CBZ, BTZ, and 4-TTri of about 80% and consequently to a distinctive shift of their ratios with unaffected compounds. Data from a seven month monitoring program at seven sampling locations at the rivers Rhine and Main in Germany revealed the best concentration correlation for ACE and CBZ (r(2) = 0.94) and also a good correlation of ACE and CBZ concentrations to BTZ and 4-TTri levels (r(2) = 0.66 to 0.82). The comparison of ratios at different sampling sites allowed for the identification of a CBZ point source. Furthermore, in Switzerland a higher consumption of SUC compared to Germany can be assumed, as a steadily increasing ACE/SUC ratio along the river Rhine was observed. In RBF wells a good correlation (r(2) = 0.85) was again observed for ACE and CBZ. Both also showed the highest stability at a prolonged residence time in the subsurface of a SAT field. In the most peripheral wells ACE and CBZ were still detected with mean values higher than 36 μg L(-1) and 1.3 μg L(-1), respectively. Although SUC concentrations in wastewater used for SAT decreased by more than 80% from about 18 μg L(-1) to 2.1 μg L(-1) and 3.5 μg L(-1) in these outlying wells, the compound was still adequate to indicate a wastewater impact in a qualitative way.  相似文献   
117.
There is concern that visitor-use associated activities, such as bathing, dish washing, wastewater production, and stock animal use near lakes and streams, could cause degradation of water quality in Yosemite National Park. A study was conducted during 2004-2007 to assess patterns in nutrient and Escherichia coli (E. coli) concentrations in the Merced and Tuolumne Rivers and characterize natural background concentrations of nutrients in the park. Results indicated that nutrient and E. coli concentrations were low, even compared to other undeveloped sites in the United States. A multiple linear regression approach was used to model natural background concentrations of nutrients, with basin characteristics as explanatory variables. Modeled nitrogen concentrations increased with elevation, and modeled phosphorus concentrations increased with basin size. Observed concentrations (±uncertainty) were compared to modeled concentrations (±uncertainty) to identify sites that might be impacted by point sources of nutrients, as indicated by large model residuals. Statistically significant differences in observed and modeled concentrations were observed at only a few locations, indicating that most sites were representative of natural background conditions. The empirical modeling approach used in this study can be used to estimate natural background conditions at any point along a study reach in areas minimally impacted by development, and may be useful for setting water-quality standards in many national parks.  相似文献   
118.
Firewood is the basic fuel source in rural Bolivia. A study was conducted in an Andean village of subsistence farmers to investigate human impact on wild firewood species. A total of 114 different fuel species was inventoried during fieldtrips and transect sampling. Specific data on abundance and growth height of wild firewood species were collected in thirty-six transects of 50 ×2 m2. Information on fuel uses of plants was obtained from 13 local Quechua key participants. To appraise the impact of fuel harvest, the extraction impact value (EIV) index was developed. This index takes into account local participants?? appreciation of (1) decreasing plant abundance; (2) regeneration capacity of plants; (3) impact of root harvesting; and (4) quality of firewood. Results suggest that several (sub-)woody plant species are negatively affected by firewood harvesting. We found that anthropogenic pressure, expressed as EIV, covaried with density of firewood species, which could entail higher human pressure on more abundant and/or more accessible species. The apparent negative impact of anthropogenic pressure on populations of wild fuel species is corroborated by our finding that, in addition to altitude, several anthropogenic variables (i.e. site accessibility, cultivation of exotics and burning practices) explain part of the variation in height of firewood species in the surroundings of Apillapampa.  相似文献   
119.
 Honeybees, Apis spp., maintain elevated temperatures inside their nests to accelerate brood development and to facilitate defense against predators. We present an additional defensive function of elevating nest temperature: honeybees generate a brood-comb fever in response to colonial infection by the heat-sensitive pathogen Ascosphaera apis. This response occurs before larvae are killed, suggesting that either honeybee workers detect the infection before symptoms are visible, or that larvae communicate the ingestion of the pathogen. This response is a striking example of convergent evolution between this "superorganism" and other fever-producing animals. Received: 2 September 1999 / Accepted in revised form: 28 February 2000  相似文献   
120.
Urban futures that are more resilient and sustainable require an integrated social–ecological system approach to urban policymaking, planning, management, and governance. In this article, we introduce the Urban Biodiversity and Ecosystem Services (URBES) and the Cities and Biodiversity Outlook (CBO) Projects as new social–ecological contributions to research and practice on emerging urban resilience and ecosystem services. We provide an overview of the projects and present global urbanization trends and their effects on ecosystems and biodiversity, as a context for new knowledge generated in the URBES case-study cities, including Berlin, New York, Rotterdam, Barcelona, and Stockholm. The cities represent contrasting urbanization trends and examples of emerging science–policy linkages for improving urban landscapes for human health and well-being. In addition, we highlight 10 key messages of the global CBO assessment as a knowledge platform for urban leaders to incorporate state-of-the-art science on URBES into decision-making for sustainable and resilient urban development.  相似文献   
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