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   64篇
  免费   7篇
  国内免费   15篇
安全科学   5篇
废物处理   1篇
环保管理   8篇
综合类   23篇
基础理论   26篇
污染及防治   18篇
评价与监测   4篇
社会与环境   1篇
  2022年   2篇
  2020年   4篇
  2019年   5篇
  2018年   1篇
  2017年   3篇
  2016年   3篇
  2015年   1篇
  2014年   1篇
  2013年   9篇
  2012年   3篇
  2011年   4篇
  2010年   2篇
  2009年   6篇
  2008年   3篇
  2007年   4篇
  2006年   3篇
  2005年   6篇
  2004年   6篇
  2003年   4篇
  2002年   4篇
  2001年   3篇
  2000年   5篇
  1999年   1篇
  1996年   2篇
  1981年   1篇
排序方式: 共有86条查询结果,搜索用时 0 毫秒
61.
以北京、西安、重庆、苏州、广州5个城市为样本,依据具身理论,从游客体验的角度探究了这5个城市夜间旅游的发展情况。结果表明:①游客对5个城市的情感倾向于中性和正向,说明游客对这5个城市夜间旅游的整体感知是基本满意的。②游客在这5个城市开展夜间旅游活动时,社会人文类的旅游目的地比自然禀赋类的旅游目的地更吸引游客。③集食、游、娱多功能于一体的旅游目的地对夜间旅游游客的吸引力大。④旅游体验感知包括景观体验感知、身体体验感知和环境体验感知,旅游体验感知对游客的夜间旅游地选择与价值内化具有较大影响。  相似文献   
62.
粪渣污泥好氧堆肥过程中主要理化性质的动态变化   总被引:2,自引:0,他引:2  
进行了粪渣污泥的强制通风静态垛堆肥试验,分析了温度、氧气、含水率和挥发性有机物在堆肥不同阶段的变化特征。粪渣与木屑质量1∶1.5的比例下,能够实现快速高温好氧堆肥,堆体温度在高温期持续9d,达到无害化的卫生学要求。堆体耗氧速率在升温阶段后期上升到最大值,此后持续降低,到堆肥后期趋于稳定。据此提出了相应的通风策略。在堆肥过程中,物料的含水率和挥发性有机物含量持续降低,但到堆肥后期趋于稳定,堆肥结束时分别减小17个百分点和10.4个百分点。  相似文献   
63.
在4.2 MW链条锅炉使用蛋壳、贝壳粉平铺在煤层上部进行炉内脱硫脱硝后,通过风机的负压携带将燃烧形成的CaO随烟气带入湿法除尘设备,完成与NaOH的双碱法脱硫脱硝。结果表明,脱硫效率 > 80%,脱硝效率 > 50%。烟气排放指标优于国标。风机携带的CaO对水冷壁形成清扫作用,运行130 d节约煤炭20%。  相似文献   
64.
为研究夜间交通事故严重程度致因,基于深圳市3年3 244起交通事故数据,获取昼夜交通事故分布的时空特征;进一步选取交通事故集聚的南山区、福田区、罗湖区的1 798起交通事故,以交通事故严重程度为因变量,以事故原因、日期、事故形态等10个因素为候选自变量,构建广义有序Logit回归模型,对比分析昼夜不同严重程度交通事故的影响因素。结果表明:路口路段类型、疲劳驾驶、事故日期在夜间模型参数估计值分别为0.493,-0.363,-0.309,而在日间模型表现为不显著,道路路面材料在日间模型参数估计值为-0.232,而在夜间表现为不显著;事故原因、道路横断面渠化方式等因素在日间和夜间所引起交通事故的严重等级均存在较大差异。  相似文献   
65.
A 3-month microcosm study was conducted to observe the potential effects of two fuels, Orimulsion and Fuel Oil #6, on the hatching success of copepod resting eggs in the seabed of Tampa Bay, Florida. Microcosms were dosed with one of five hydrocarbon treatments via hydrocarbon-coated sand and compared with controls. Acartia tonsa eggs were nonviable in all treatments after only a few weeks of incubation, as evidenced by a marked decline in the abundance of nauplii. However, there was no evidence that exposure to simulated spills of 700 or 7000 ppm of either fuel led to significant increases in resting egg mortality as compared with controls. The results further indicate that, regardless of environmental conditions, resting eggs of A. tonsa do not remain viable in the sediment for extended periods of time.  相似文献   
66.
我国粪便处理的现状分析及发展   总被引:7,自引:2,他引:7  
根据我国粪便处理的现状,分析我国粪便处理存在的问题,明确粪便无害化处理的必然趋势。并对粪便无害化处理的工艺、产品出路进行比较和分析。  相似文献   
67.
The residual levels of antibiotics in Vietnamese eggs were monitored from 2014 to 2015. A total of 111 egg packages, distributed by 11 different companies, were collected from supermarkets in Ho Chi Minh City and the levels of 28 antibiotics were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) screening method. Sixteen samples tested positive for antibiotics; a total of eight compounds (enrofloxacin, ciprofloxacin, norfloxacin, sulfadimethoxine, sulfamethazine, sulfamonomethoxine, tilmicosin and trimethoprim) were detected. Enrofloxacin was detected in eight samples, with two samples exhibiting concentrations exceeding 1,000 µg kg?1. Tilmicosin was detected in three samples at a range of 49–568 µg kg?1. We observed that two of the 11 companies frequently sold antibiotic-contaminated eggs (detection rates of 56 and 60%), suggesting that a number of companies do not regulate the use of antibiotics in egg-laying hens. Our findings indicate that livestock farmers require instruction regarding antibiotic use and that continual antibiotic monitoring is essential in Vietnam.  相似文献   
68.
ABSTRACT

In the era of developing technologies, there is always been a crisis of rising demands of energy. There is no skepticism that a lot of energy is being produced every hour for almost each and every field, but still an exploration is needed to come up with new and viable options for energy creation. The same is the objective of this paper which proposes the use of waste biomaterials in association with organic and inorganic materials as a source of energy to power up small electronic devices. In this research egg shell membrane (ESM)-based triboelectric nanogenerator (TENG) is proposed in combination with calotropis (Calo), cellulose from fruit of Bombax Ceiba (BOM), cellulose in form of tissue paper (TISU), dog hair (DH), polytetrafluoroethylene (PTFE), aluminum (Al), and copper (Cu). ESM is eco-friendly waste food by-product and available in abundance. Characterization of ESM is done by scanning electron microscope (SEM), atomic force microscope (AFM), X-ray diffraction (XRD), and Fourier transform infrared spectrophotometer (FTIR). The proposed ESM-PTFE-based TENG power up 462 green LEDs (462 × 2 V = 924 V ~ 1 kV) without rectifier and produced up to 7.61 µJ energy with 4.7 µF capacitor at 200 tapings. All the proposed ESM-based TENG combinations generate sufficient voltage to turn ON the wrist watch. This green-energy-based TENG has potential application in various fields especially related to medical devices.  相似文献   
69.
Abstract

The effects of various concentrations of ammonium sulphate and urea on egg hatching and miracidial survival of S. mansoni were tested in order to determine if the use of these fertilizers in the ricelands of the Republic of Cameroon could affect the transmission of schistosomiasis. Results indicate that hatching of eggs and survival of miracidia varied with concentrations of tested chemicals and times of exposure. Exposure of S. mansoni eggs to 0.20%‐1.00% ammonium sulphate or to 0.50%‐4.00% urea reduced their ability to hatch and produce miracidia. A chemical concentration of 1.00% ammonium sulphate or 4.00% urea was found to be sufficient to produce complete inhibition of hatching. High concentrations of both chemicals not only inhibited miracidial emmergence but also may be ovocidal. Results obtained from miracidial survival tests indicated that LC5, LC50 and LC95 values for ammonium sulphate were 0.07%, 0.80% and 10.61% after 2 hours of exposure; 0.03%, 0.16% and 0.90% after 4 hours of exposure; and 0.30%, 0.20% and 0.40% after 6 hours of exposure respectively. Similar statistical analyses revealed that the LC5, LC50 and LC95 values for urea were 0.22%, 1.90% and 16.25% after 2 hours of exposure; 0.28%, 0.57% and 1.14% after 4 hours of exposure; and 0.13%, 0.27% and 0.57%” after 6 hours of exposure respectively. Although the two fertilizers exerted some adverse effects on S. mansoni eggs and miracidia at relatively high concentrations, neither of them was found to be of practical value. Ammonium sulphate and urea concentrations effective in killing S. mansoni eggs and miracidia were about one to two orders of magnitude greater than the actual field application rates.  相似文献   
70.
The main purpose of this work is to investigate the characteristics of night soil and leaf co-composting using aerobic static composting method. Three influencing factors, including proportion of night soil and leaf, aeration rate and aeration pattern, were investigated through the evolution of the principal physicochemical properties, i.e., temperature, oxygen consumption rate, organic matters, moisture content, carbon, nitrogen, carbon-to-nitrogen ratio and Germination index (GI). It was found that the 3∶1 (w∶w) mixture of night soil and leaf was capable of achieving the highest composting temperature, longest retention time of high temperature (55°C), and fastest organic matter degradation. The 0.14 m3·min-1·m-3 aeration rate was most beneficial to composting, and the mixture of night soil and leaf maintained the highest temperature for the longest duration and achieved the highest CO2 content and GI. The continuous aeration pattern during composting was superior to an intermittent aeration pattern, since the latter delayed the composting process.  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