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   739篇
  免费   49篇
  国内免费   108篇
安全科学   115篇
废物处理   37篇
环保管理   77篇
综合类   320篇
基础理论   199篇
环境理论   7篇
污染及防治   96篇
评价与监测   14篇
社会与环境   26篇
灾害及防治   5篇
  2023年   16篇
  2022年   12篇
  2021年   32篇
  2020年   35篇
  2019年   43篇
  2018年   31篇
  2017年   48篇
  2016年   53篇
  2015年   45篇
  2014年   63篇
  2013年   109篇
  2012年   31篇
  2011年   39篇
  2010年   29篇
  2009年   51篇
  2008年   19篇
  2007年   30篇
  2006年   27篇
  2005年   28篇
  2004年   26篇
  2003年   21篇
  2002年   17篇
  2001年   25篇
  2000年   11篇
  1999年   12篇
  1998年   5篇
  1997年   6篇
  1996年   5篇
  1995年   10篇
  1993年   1篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1989年   4篇
  1987年   3篇
  1986年   2篇
  1985年   3篇
  1983年   1篇
排序方式: 共有896条查询结果,搜索用时 62 毫秒
61.
Fast pyrolysis of chicken manure produced two biooils (Fractions I and II) and a residual char. All four materials were analyzed by chemical methods, 13C and 1H Nuclear Magnetic Resonance Spectrometry (13C and 1H NMR), and Fourier Transform Infrared Spectrosphotometry (FTIR). The char showed the highest C content and the highest aromaticity. Of the two biooils Fraction II was higher in C, yield and calorific value but lower in N than Fraction I. The S and ash content of the two biooil fractions were low. The Cross Polarization Magic Angle Spinning (CP-MAS) 13C NMR spectrum of the initial chicken manure showed it to be rich in cellulose, which was a major component of sawdust used as bedding material. Nuclear Magnetic Resonance (NMR) spectra of the two biooils indicated that Fraction I was less aromatic than Fraction II. Among the aromatics in the two biooils, we were able to tentatively identify N-heterocyclics like indoles, pyridines, and pyrazines. FTIR spectra were generally in agreement with the NMR data. FTIR spectra of both biooils showed the presence of both primary and secondary amides and primary amines as well as N-heterocyclics such as pyridines, quinolines, and pyrimidines. The FTIR spectrum of the char resembled that of the initial chicken manure except that the concentration of carbohydrates was lower.  相似文献   
62.
The high‐performance liquid‐chromatographic retentions of red‐wine pesticide residues are modeled by structure–property relationships. The effect of different types of features is analyzed: geometric, lipophilic, etc. The properties are fractal dimensions, partition coefficient, etc., in linear and nonlinear correlation models. Biological plastic evolution is an evolutionary perspective conjugating the effect of acquired characters and relations that emerge among the principles of evolutionary indeterminacy, morphological determination and natural selection. It is applied to design the co‐ordination index that is used to characterize pesticide retentions. The parameters used to calculate the co‐ordination index are the molar formation enthalpy, molecular weight and surface area. The morphological and co‐ordination indices barely improve the correlations. The fractal dimension averaged for non?buried atoms, partition coefficient, etc. distinguishes the pesticide molecular structures. The structural and constituent classification is based on nonplanarity, and the number of cycles, and O, S, N and Cl atoms. Different behavior depends on the number of cycles.  相似文献   
63.
Dissolved organic matter (DOM) is a ubiquitous constituent of natural waters and is comprised of a variety of chemically heterogeneous molecular structures and functional groups. DOM is often considered to be a major ligand for metals in most natural waters and its reactivity is thought to be strongly dependent on its chemical composition and structure. In this study, a combination of UV/visible, emission excitation matrix fluorescence (EEM) and 1H NMR spectroscopies were used to characterize DOM from the Athabasca River (Alberta, Canada). The chemical characterization of river DOM showed that the most upstream samples located in agricultural areas were blue-shifted and less aromatic and contained more hydrogens connected with oxygen functional groups than those in the wetland dominated area in the Athabasca oil sand deposit region. The presence of paramagnetic ions (Fe and Al) was not found to significantly affect the structural composition of DOM as revealed by 1H NMR. Such change in the quality of DOM may have a profound impact on metal binding in the Athabasca River watershed.  相似文献   
64.
樊丽  徐龙君  王辉 《环境工程学报》2012,6(8):2809-2812
为考察较低温度(<17℃)条件下添加微量金属元素对厌氧发酵产气量的影响,在发酵底物TS(含固率)为10%下采用10 L玻璃瓶作反应器,以牛粪为原料,向厌氧生物反应器中分别添加MnSO4、FeSO4·7H2O、电解锰渣,分析了厌氧消化系统运行过程中的产气量、COD(化学需氧量)和pH的变化。结果表明,锰元素能促进低温下牛粪的厌氧发酵,加速反应启动。当添加6 g MnSO4、100 g电解锰渣时,单位质量VS产气率分别为0.26 mL/g和0.64 mL/g,添加6 g FeSO4·7H2O与空白对照组均未见明显产气。  相似文献   
65.
Microbial inhibitors such as mercuric chloride are frequently used to sterilize soil or soil–water slurries in experimental studies on the fate of xenobiotics in the environment. This study examined the influence of mercuric chloride additions to soil–water slurries on the sorptive behaviour of a phenoxy herbicide (2,4-D) in soil. The results demonstrated that mercuric chloride strongly decreased the capacity of the soil to retain herbicides, and that the interference of mercuric chloride with herbicide sorption increased with increasing soil organic carbon contents. Because of the competitive sorption between mercuric chloride and the phenoxy herbicide, we conclude that mercuric chloride may not be a good soil sterilization procedure for use in xenobiotic fate studies.  相似文献   
66.
改性氧化铝微波诱导催化氧化处理高浓度苯酚废水的研究   总被引:4,自引:0,他引:4  
采用微波诱导催化氧化技术,以改性氧化铝为催化剂,对高浓度模拟苯酚废水进行氧化处理。考察了微波功率、催化剂投加量、H202投加量、废水pH值和微波反应时间等因素对苯酚去除效果的影响。实验结果表明,处理30mL质量浓度为1 100mg/L的苯酚模拟废水,在微波功率500W,催化剂加入量1 g(液固比30∶1),30%双氧水...  相似文献   
67.
基于GIS与RUSLE的武陵山区小流域土壤侵蚀评价研究   总被引:1,自引:0,他引:1  
以长江中下游武陵山区女儿寨小流域为研究区,基于数据观测积累及实地调查采样等方法,计算了研究区降雨侵蚀力、土壤可蚀性等因子,运用GIS与RUSLE评价了流域土壤侵蚀强度并分析了其与土地利用方式、海拔高度的关系。结果表明,流域平均土壤侵蚀强度为78844 t/(km2·a),属微度侵蚀,流域面积9518%的范围发生轻度以下的侵蚀,强烈以上侵蚀仅占1.19%。从土地利用类型来看,耕地、果园侵蚀强度较大,均达到中度侵蚀,有林地除竹林地为轻度侵蚀外均属微度侵蚀,耕地、果园、竹林地是今后水土流失防治的主要地类。不同海拔高度中,低海拔(200~400 m)区域侵蚀量占到流域侵蚀总量的6442%,是水土流失防治的重点地带。研究为应用修正通用土壤流失方程在武陵山区进行土壤侵蚀评价提供范例,为研究区防治土壤侵蚀和流域管理规划决策提供相应参考  相似文献   
68.
H2S、NH3混合臭气在生物滴滤池中的净化研究   总被引:1,自引:0,他引:1  
研究了生物滴滤塔净化含H2S与NH3臭气最佳的生态条件为:在温度为25 ℃、气体通气量为0.4 m3/h、营养盐喷淋量为8.0 L/h、入口H2S质量浓度712.80-948.80 mg/m3、入口NH3质量浓度422.20-795.40 mg/m3、pH值7.0-8.0之间的情况下,去除效率可达90%以上.生物滴滤塔在处理H2S和NH3混合气时,塔内pH值保持在6.5-8.5之间,此pH值对反应器中优势菌的生长繁殖不会造成太大影响,对处理效果影响不大,因此反应过程可不用对pH值进行调节,节约运行成本.  相似文献   
69.
The adsorption behaviour of Basic Red 12, Acid Orange 7 and Acid Blue 1 on zinc oxide nanoparticles (ZNP) has been investigated to understand the physicochemical process involved and to explore the possible use of nanoparticles in the treatment and management of textile waste matter. The dye removal capacity of ZNP towards Basic Red 12, Acid Orange 7 and Acid Blue 1 was found to be 15.64, 6.78 and 6.38 mg g?1, respectively. The adsorption process was pH dependent and optimum pH values of 9.0, 2.0 and 4.0 were obtained for Basic Red 12, Acid Orange 7 and Acid Blue 1, respectively. Equilibrium was established after 1.0 h for all dyes. Langmuir, Freundlich and Temkin isotherm models were applied to the system. The adsorbent ZNP was characterised using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) and Fourier transform infrared (FTIR) techniques. SEM analysis revealed the noticeable nanoporous morphology of the material. The results of FTIR spectroscopy showed that the process is driven by an electrostatic complexation mechanism. XRD studies revealed the nanocrystalline structure of ZNP. BET surface area measurement suggested a high pore volume and large surface area for the adsorbent. The kinetic measurements suggested pseudo-second-order kinetic processes with high regression coefficients and smaller standard error of estimate values and lower residual sum of squares. The thermodynamic measurements suggested that all processes were exothermic and accompanied by negative values for Δ G0, Δ S0 and Δ H0.  相似文献   
70.
通过对膨润土的羟基铝改性实验大大提高了膨润土对染料废水的处理效率。实验结果表明:改性膨润土对变色酸有很好的去除效果,对H酸有较好的去除效果,对T酸处理效果一般,对吐氏酸几乎没有效果。  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