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   903篇
  免费   8篇
  国内免费   13篇
安全科学   30篇
废物处理   54篇
环保管理   77篇
综合类   104篇
基础理论   186篇
环境理论   6篇
污染及防治   211篇
评价与监测   69篇
社会与环境   184篇
灾害及防治   3篇
  2024年   1篇
  2023年   8篇
  2022年   37篇
  2021年   25篇
  2020年   11篇
  2019年   25篇
  2018年   43篇
  2017年   41篇
  2016年   78篇
  2015年   26篇
  2014年   76篇
  2013年   93篇
  2012年   51篇
  2011年   65篇
  2010年   58篇
  2009年   55篇
  2008年   46篇
  2007年   53篇
  2006年   21篇
  2005年   32篇
  2004年   18篇
  2003年   13篇
  2002年   13篇
  2001年   8篇
  2000年   7篇
  1999年   1篇
  1998年   1篇
  1997年   4篇
  1996年   4篇
  1995年   1篇
  1993年   3篇
  1990年   1篇
  1988年   1篇
  1979年   1篇
  1973年   2篇
  1972年   1篇
排序方式: 共有924条查询结果,搜索用时 20 毫秒
851.
Monitoring of day-active butterflies by water pan traps method over the period 2001–2012 was conducted on a gradually overgrowing habitat in Ko?ick? kotlina basin (Slovakia). Totally, 1457 individuals of 57 species of butterflies were caught and evaluated. Monitoring revealed significant changes in the butterfly community which might be a consequence of a gradual overgrown of the study area. During the research, 12 butterfly species have disappeared from the study area. The monitoring provided results which point to the necessity of appropriate management for conservation of rare and protected butterfly species.  相似文献   
852.
853.
In certain environments nutrient and energy sources available to microorganisms can be limited. Foodborne pathogens must efficiently adapt in order to be successfully transmitted through the food chain to their hosts. For the intracellular foodborne pathogen Listeria monocytogenes, little is known regarding its response to nutrient/energy-limiting conditions. The alternative stress responsive sigma factor σB has been reported to contribute to survival under specific stresses. Therefore, the effects of several metabolic inhibitors on growth of L. monocytogenes wild-type and a ΔsigB mutant were examined. In the absence of inhibitors, both strains reached stationary phase after 18 h at 23°C and 10 h at 37°C. All of the metabolic inhibitors slowed growth of either strain, with few differences observed among the different inhibitors.  相似文献   
854.
A new differential display-polymerase chain reaction (PCR) method based on annealing control primers was used to screen and identify potential biomarkers from differentially expressed genes (DEGs) in medaka exposed to sub-lethal concentration of diazinon (100 ppb). Among the differentially expressed genes identified, the majority were in functional categories of protein biosynthesis, transport and metabolism according to the gene ontology classification. The differential expression of ribosomal protein genes was quantified by real time PCR. The genes encoding ribosomal proteins including L3 and S17 were selected as potential biomarkers for diazinon exposure in medaka fish.  相似文献   
855.
Abstract

A two-stage mathematical model for Hg removal using powdered activated carbon injection upstream of a bag-house filter was developed, with the first stage accounting for removal in the ductwork and the second stage accounting for additional removal caused by the retention of carbon particles on the filter. The model shows that removal in the ductwork is minimal, and the additional carbon detention time from the entrapment of the carbon particles in the fabric filter enhances the Hg removal from the gas phase. A sensitivity analysis on the model shows that Hg removal is dependent on the isotherm parameters, the carbon pore radius and tortuosity, the C/Hg ratio, and the carbon particle radius.  相似文献   
856.
The current food waste leachate (FWL) disposal practice in Korea warrants urgent attention and necessary action to develop an innovative and sustainable disposal strategy, which is both environmentally friendly and economically beneficial. In this study, methane production by FWL injection into a municipal solid waste landfill with landfill gas (LFG) recovery facility was evaluated for a period of more than 4 months. With the target of recovering LFG with methane content ~50%, optimum LFG extraction rate was decided by a trial and error approach during the field investigation in five different phases. The results showed that, upon FWL injection, LFG extraction rate of ~20 m(3)/h was reasonable to recover LFG with methane content ~58%. Considering the estimated methane production potential of 31.7 m(3) CH(4) per ton of FWL, methane recovery from the landfill was enhanced by 14%. The scientific findings of this short-term investigation indicates that FWL can be injected into the existing sanitary landfills to tackle the present issue and such landfills with efficient liner and gas collection facility can be utilized as absolute and sustainable environmental infrastructures.  相似文献   
857.
The objective of this work was to manufacture biodegradable films by two different processes (casting and extrusion), from different combinations of cassava starch and xanthan gum. These films were produced by casting and by extrusion from six different starch-xanthan gum combinations (0, 2, 4, 6, 8 and 10% w/w), containing glycerol as plasticizer (20% w/w) and were also characterized according to their microstructure, optical, mechanical, and barrier properties. Scanning electron microscopy of the starch-xanthan gum extruded films showed reticulated surface and smooth interior, suggesting that xanthan was driven to the surface and gelatinized starch to the interior of the films during extrusion. Films manufactured by casting were entirely homogeneous. In general, casted films presented lower opacity and water vapor permeability and higher stress at break than films manufactured by extrusion. Xanthan gum addition affected mechanical properties of starch films, improving their stress and strain at break, especially for extruded samples, but these properties did not show stability at different RH conditions.  相似文献   
858.
The purpose of this study is to introduce an efficient drying method named “fry-drying technology” for the treatment of sewage sludge. The basic principle of this method lies in the rapid escape of moisture from sludge material through its pores into the oil medium driven by the strong pressure gradient formed between sludge and oil media. This beneficial pressure distribution for moisture transfer can be established by the subtle combination of the difference of physical properties of specific heat and boiling temperature between water and oil. In order to determine the physical characteristics of this fry-drying technology, a series of experiments were performed in which important parameters, such as heating oil temperature, drying time, oil type, and sludge size, were varied. Numerical calculations using a single solid spherical particle model without any porosity were used to resolve the particle size effect associated with sludge drying.  相似文献   
859.
Methodical approaches to forest biomass and net primary production estimating are studied and their regression models are designed. By means of combining these models and State Forest Account database of 305 forest enterprises of the Ural region the total forest biomass (9.11 billion tons) and net primary production (542 million tons) are calculated. The models and calculating algorithms are involved into the information system on the base of the Software AG platform Natural, which allows to estimate and to re-calculate forest biomass and net primary production on some territory in automatic mode.  相似文献   
860.
Perfluorinated compounds (PFCs) measured in surface running waters indicated the existence of different emission sources in eight main city basins. The tap water reflected the contamination pattern and levels in their corresponding source water basins. The daily intakes through tap water consumption ranged from <0.01 to 0.73 ng kg−1 d−1 for perfluorooctanoate (PFOA) and <0.01 to 0.08 ng kg−1 d−1 for perfluorooctanesulfonate (PFOS). Tap water intake-derived exposure accounted for 8.6%-101% (for PFOA) and while <10% (for PFOS) of total daily exposure, which was estimated from Korean serum concentrations using a pharmacokinetic model. Our findings indicate that tap water intake could be an important contributor to PFOA exposure in Korean populations; accordingly, additional efforts are necessary to improve the removal efficiency of perfluorinated compounds (PFCs) in the water purification process. However, more fundamentally the aim would be to reduce the discharge of PFCs from potential sources within the basin.  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