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   169篇
  免费   38篇
  国内免费   59篇
安全科学   31篇
废物处理   3篇
环保管理   21篇
综合类   133篇
基础理论   36篇
污染及防治   4篇
评价与监测   6篇
社会与环境   12篇
灾害及防治   20篇
  2023年   5篇
  2022年   16篇
  2021年   15篇
  2020年   12篇
  2019年   16篇
  2018年   5篇
  2017年   7篇
  2016年   13篇
  2015年   9篇
  2014年   13篇
  2013年   16篇
  2012年   17篇
  2011年   17篇
  2010年   11篇
  2009年   17篇
  2008年   16篇
  2007年   14篇
  2006年   7篇
  2005年   5篇
  2004年   11篇
  2003年   7篇
  2002年   7篇
  2001年   6篇
  2000年   3篇
  1999年   1篇
排序方式: 共有266条查询结果,搜索用时 427 毫秒
61.
漆酶对染料的脱色研究   总被引:4,自引:0,他引:4  
利用来源于白毒鹅膏菌的粗漆酶与12种工业染料反应,结果发现其中7种染料颜色能被脱除.研究了直接影响黑G和中性黄GL的漆酶脱色的相关因素.试验发现,这两种染料在1h内与漆酶反应迅速,且特征颜色吸收峰(600nm/440nm )基本消失,其最适温度均为50℃、最适反应pH值范围分别为5-6和3-4,酶活力的增加可显著提高反应速率,但对总脱色率影响不大.在pH值为5、温度40℃条件下,5U/ml的漆酶与直接黑G和中性黄GL反应的Km值分别为3.2mg/L和25.1mg/L,Vmax值分别为2.70mg/L·min和3.25mg/L·min.  相似文献   
62.
以活性污泥为研究对象,研究了污泥中红斑顠体虫的生长情况以及红斑顠体虫对污泥减量的影响.结果表明:(1)红斑顠体虫的培养温度应该保持在20℃以上.在低污泥负荷(F/M) (<0.4 mg/(mg·d))下,红斑顠体虫均能大量出现.(2)当温度大于20℃、红斑顠体虫处于生长期的活性污泥浓度(MLSS)>3.0 g/L时,红...  相似文献   
63.
In the present work, we verified a 3D computational fluid dynamics model for vertical slot fish-passes (VSFs) that employs the renormalization-group k-epsilon turbulence model (RNG KE) and the volume of fluid (VOF) method. We compared model calculations with experiments in two pool designs T1 and T2 of an experimental VSF and with 2D calculations using the shallow water equations (SWE) and the standard k-epsilon (2D SKE) model. Calculations of the 3D model showed (1) good agreement with experiments and 2D calculations in predicting mean flow velocities, (2) better performance in the determination of the water surface in the VSF, which is attributed to the accurate VOF method, (3) superior prediction of turbulence characteristics than the 2D model, which is due to the 3D RNG KE model that overcomes the problem of turbulence overestimation of the 2D SKE model, and to the fact that the 3D model takes into account the 3D features of the flow in the fish pass. Moreover, the present 3D calculations showed that the common assumptions in VSFs that (1) the flow is 2D, and (2) the simulation of 4 pools of a VSF is sufficient to obtain satisfactory results, are not always valid. Flow can be considered as 2D only in pool design T2 and for certain geometries and flow characteristics in pool design T1; while, eventually, all the pools of a fish pass need to be modeled to ensure accurate results. Finally, the present work illustrates the need to perform fish experiments simultaneously with flow experiments.  相似文献   
64.
本文基于一次能源消费的统计数据,计算了四川省2000~2009年的碳排放总量、人均碳排放量和碳排放强度。结果表明:2000~2009年四川省能源消费总量、碳排放总量和人均碳排放量均呈显著上升趋势;第二产业碳排放量的比重最大,并且增大趋势明显;2000~2009年四川省碳排放强度年平均下降率小于国内生产总值的年平均增长率,未能实现二氧化碳的绝对减排。  相似文献   
65.
A preliminary investigation was performed to estimate the effect of the degree of treatment in Sewage Treatment Plants (STPs) on the status of pollution along the coastlines of the Mediterranean Sea. Data from questionnaires and the literature were collected and processed (a) to identify 18 approximate 1D surface coastal currents, (b) to estimate their prevailing direction and average flow velocity and (c) to estimate the water pollution loads and identify their locations of discharge. Then, a simplified 1D water quality model was formulated and applied for the existing conditions and two hypothetical scenarios: (1) all coastal cities have STPs with secondary treatment and (2) all coastal cities have STPs with tertiary treatment to determine BOD(5), TN and TP concentrations in the 18 surface coastal currents. Calculated concentrations were compared and discussed. A main conclusion is that, to reduce pollution in the Mediterranean Sea measures should be adopted for upgrading the water quality of the rivers discharging into the Mediterranean Sea, along with the construction of STPs for all the coastal cities.  相似文献   
66.
In this paper we developed a general stage-structured, Leslie-type model, suitable to simulate dynamics of soil arthropods under typical Mediterranean conditions. In order to explore arthropods’ life-history strategies in relation to enhanced spatial heterogeneity of the Mediterranean ecosystems, metapopulation characteristics were considered and different habitat quality regimes, in terms of dominant microclimatic conditions, were taken into account. Environmental stochasticity in temperature and humidity was incorporated into the model, and an elasticity analysis was conducted to quantify contribution of different life-history traits to metapopulation growth rate. The application of the model revealed well-known life-cycle characteristics of Mediterranean arthropods, such as seasonally fluctuating population sizes and skewing phenologies, a fact that confirms models’ reliability. Furthermore, the model seems able to elucidate controversial points of the animals’ life-cycle development, such as the long-term maintenance of populations in the field and the underlying mechanisms related to the adjustment to the specific features of the Mediterranean ecosystem. Subpopulations inhabiting various microsites display different dynamics and the interaction between these subpopulations, via dispersion, seems to be able to ensure stochastic equilibrium for the system. Dispersal appears to play a decisive role, allowing arthropods to conform to spatial severities and habitats fragmentation, rescuing individuals and recolonizing previously extinct habitats.  相似文献   
67.
基于CFD的井喷失控喷射火温度场和辐射场模拟仿真   总被引:1,自引:0,他引:1  
采用CFD方法研究了井喷失控喷射火,阐述了模拟仿真所需的定解条件,论述了模拟仿真采用的数值计算方法,通过模拟仿真得出了井喷失控喷射火温度场和热辐射场的分布规律.结论表明采用CFD方法研究井喷失控喷射火是切实可行的.  相似文献   
68.
简述了某钢厂将石灰窑烟气中的CO2回收,制成食品级CO2的工艺概况及其综合利用效益,为工业尾气CO2资源化循环利用提供了示范。  相似文献   
69.
喀斯特山区是生态环境相对脆弱的地带,其生态功能受地质环境的影响。以国家重点生态功能区罗甸县为研究区,选取水土流失、石漠化、生境以及气象要素四个评价指标,利用栅格数据GIS空间分析方法对各评价因子进行量化提取,采用层次分析法和综合指标法,对各评价指标进行空间叠加分析,划分出研究区域生态环境敏感性等级,评价和分析了罗甸县域生态环境敏感性程度及其空间分布状况。结果表明:罗甸县生态环境敏感评价以中度以下敏感为主,中度以下敏感区域占县域总面积的98.12%,高度以上敏感区域极少。地质背景、地形地貌以及气候是导致罗甸县生态环境敏感的主导因素。  相似文献   
70.
铜藻基生物炭的水热制备及性能表征   总被引:1,自引:1,他引:0  
以浙江优势大型海藻之一的铜藻为原料,采用水热炭化法制备了生物炭.同时,通过正交法,以碳回收率和得率为指标,考察了反应时间、反应温度及铜藻与去离子水质量比等因素的影响,确定制备水热炭的最佳工艺条件.结果表明,制备铜藻基水热炭的最佳工艺条件为:反应时间2 h,反应温度180℃,铜藻与去离子水质量比1/4,在此条件下,水热炭的碳回收率为65.0%,得率为51.4%.元素分析、BET、接触角测定和傅里叶红外表征结果表明,铜藻基水热炭比表面积为26.6 m2·g-1,pH值为4.8,具有较高的O/C和较低的C/N,与干法裂解炭相比,其亲水性更强,且表面具有更为丰富的含氧、含氮官能团,灰分含量更低,得率和碳回收率分别提高了53.4%和33.5%.  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