全文获取类型
收费全文 | 1754篇 |
免费 | 118篇 |
国内免费 | 512篇 |
专业分类
安全科学 | 169篇 |
废物处理 | 67篇 |
环保管理 | 129篇 |
综合类 | 1005篇 |
基础理论 | 288篇 |
污染及防治 | 337篇 |
评价与监测 | 143篇 |
社会与环境 | 154篇 |
灾害及防治 | 92篇 |
出版年
2024年 | 8篇 |
2023年 | 36篇 |
2022年 | 106篇 |
2021年 | 81篇 |
2020年 | 84篇 |
2019年 | 60篇 |
2018年 | 84篇 |
2017年 | 90篇 |
2016年 | 81篇 |
2015年 | 94篇 |
2014年 | 104篇 |
2013年 | 159篇 |
2012年 | 113篇 |
2011年 | 116篇 |
2010年 | 88篇 |
2009年 | 140篇 |
2008年 | 114篇 |
2007年 | 96篇 |
2006年 | 117篇 |
2005年 | 60篇 |
2004年 | 73篇 |
2003年 | 75篇 |
2002年 | 89篇 |
2001年 | 68篇 |
2000年 | 72篇 |
1999年 | 41篇 |
1998年 | 28篇 |
1997年 | 20篇 |
1996年 | 22篇 |
1995年 | 15篇 |
1994年 | 17篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 10篇 |
1990年 | 4篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 3篇 |
排序方式: 共有2384条查询结果,搜索用时 640 毫秒
161.
为了解棉花耐涝相关种质资源的遗传多样性,选用均匀分布于棉花全基因组的145对引物,从中筛选出44对SSR引物对48份涝相关种质资源进行遗传多样性分析。结果表明,44对SSR引物在48份材料中共检测出170个等位基因变异,平均每个位点有386个。其中耐涝材料的位点多态信息含量(PIC)、每个位点的有效等位基因数(Ne)、基因型多样性(H′)分别为0632、1710 4和0393 7,涝敏感材料的PIC、Ne、H′分别为0628、1721 6和0399 4。耐涝材料和涝敏感材料的Jaccard相似性系数分别在0462~0925和0398~0845之间,遗传相似性系数总体平均值接近,但耐涝材料的变化幅度更大。用类平均法(UPGMA)聚类将48份材料分成2个类群。其中,第Ⅰ类包含39个品种,第Ⅱ类包含9个品种。大多数材料之间的遗传相似性系数较高,表明陆地棉耐涝相关种质资源遗传基础狭窄。本结果可为棉花耐涝育种亲本选配和相关机理研究提供基础资料 相似文献
162.
蒸散的估算在区域能量平衡和水资源研究中具有重要意义,遥感技术发展促进了区域蒸散的研究。利用安徽省气象资料、MODIS数据产品及GIS背景信息,基于SEBAL模型,按1 km空间分辨率进行了面尺度的安徽省日蒸散量估算,并在GIS空间分析模块的支持下对不同土地覆盖类型的日蒸散量进行统计分析。结果表明:遥感估算的蒸散量与利用Penman Monteith公式计算的蒸散量比较,两者之间具有较好的相关性,遥感蒸散估算值整体偏小,不同土地利用类型的日蒸散量间差异显著。遥感蒸散估算方法在安徽省具有一定的实用性,需优化模型参数,以提高其进一步技术推广的前景 相似文献
163.
Properties of Pyrolytic Chars and Activated Carbons Derived from Pilot-Scale Pyrolysis of Used Tires
S.-Q. Li Q. Yao S.-E. Wen Y. Chi J.-H. Yan 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1315-1326
Abstract Used tires were pyrolyzed in a pilot-scale quasi-inert rotary kiln. Influences of variables, such as time, temperature, and agent flow, on the activation of obtained char were subsequently investigated in a laboratory-scale fixed bed. Meso-porous pores are found to be dominant in the pore structures of raw char. Brunauer-Emmett-Teller (BET) surfaces of activated chars increased linearly with carbon burnoff. The carbon burnoff of tire char achieved by carbon dioxide (CO2) under otherwise identical conditions was on average 75% of that achieved by steam, but their BET surfaces are almost the same. The proper activation greatly improved the aqueous adsorption of raw char, especially for small molecular adsorbates, for example, phenol from 6 to 51 mg/g. With increasing burnoff, phenol adsorption exhibited a first-stage linear increase followed by a rapid drop after 30% burnoff. Similarly, iodine adsorption first increased linearly, but it held as the burnoff exceeded 40%, which implied that the reduction of iodine adsorption due to decreasing micro-pores was partially made up by increasing mesopores. Both raw chars and activated chars showed appreciable adsorption capacity of methylene-blue comparable with that of commercial carbons. Thus, tire-derived activated carbons can be used as an excellent mesoporous adsorbent for larger molecular species. 相似文献
164.
165.
铁炭微电解工艺处理采油废水的研究 总被引:2,自引:1,他引:1
随着采油废水产生量的逐渐增大以及排放标准的日益严格,寻找一种经济、高效的处理方法显得十分必要。采用铁炭微电解技术对冀东油田采油废水进行了处理。考察了铁屑粒径、pH值、Fe/C质量比和反应时间对COD去除率的影响并设计了正交实验,结果表明,影响微电解工艺的因素主次关系为:pH>Fe/C质量比>反应时间,在最佳条件pH=5,Fe/C质量比为7∶1,反应时间50 min下,原水COD由170 mg/L降至95.6 mg/L,去除率达43.85%,出水满足国家二级排放标准。 相似文献
166.
Fe3O4/SDS磁性纳米颗粒吸附水体中的Cd2+和Zn2+ 总被引:3,自引:1,他引:2
一种新型纳米固相萃取吸附剂,由阴离子表面活性剂十二烷基磺酸钠(SDS)包裹在Fe3O4磁性纳米颗粒表面形成,用于吸附水溶液中的重金属离子。研究了吸附过程的主要影响因素(如SDS浓度、溶液pH等)以及解吸过程的最佳条件,并对其机理进行了初步的探讨。研究结果表明,共沉淀法制备的Fe3O4颗粒粒径分布均匀,平均粒径约为54 nm;SDS浓度为300 mg/L时,Fe3O4/SDS磁性纳米颗粒吸附Cd2+和Zn2+的能力最强;在一定浓度范围内,Fe3O4/SDS体系对Cd2+和Zn2+的吸附平衡数据符合Langmuir吸附等温方程,饱和吸附量分别为22.42 mg/g和13.95 mg/g。最终结果表明,Fe3O4/SDS磁性纳米颗粒具有较强磁分离能力和较好的吸附效果。 相似文献
167.
168.
石油污染土壤原位生物修复的强化实验研究 总被引:2,自引:0,他引:2
为研究添加营养物质和高效降解石油微生物对油污土壤生物修复的作用,通过分层土柱的方法,连续监测了不同条件下不同土层的含水率、石油烃含量、细菌数量及脱氢酶活性。结果表明:添加营养物质同时接种高效微生物可使降解效果明显改善,降解率比在自然条件下提高近50%,而单纯添加营养物质不接种高效微生物可使降解率比在自然条件下提高约25%。降解初期,上层土壤降解效果较好,而到中后期,中下层降解效果好于上层。微生物数量和脱氢酶活性与石油降解率之间存在良好的相关性,脱氢酶活性比微生物数量更能反映修复过程中微生物的存活状态。添加营养物质和高效降解石油微生物对油污土壤原位生物修复具有强化作用。 相似文献
169.
Atmospheric deposition of phthalate esters in a subtropical city 总被引:1,自引:0,他引:1
Feng Zeng Yujun Lin Kunyan Cui Jiaxin Wen Yongqin Ma Hongli Chen Fang Zhu Zhiling Ma Zunxiang Zeng 《Atmospheric environment (Oxford, England : 1994)》2010,44(6):834-840
In Chinese cities, air pollution has become a serious and aggravating environmental problem undermining the sustainability of urban ecosystems and the quality of urban life. Bulk atmospheric deposition samples were collected two-weekly, from February 2007 to January 2008, at three representative areas, one suburban and two urbanized, in the subtropical city, Guangzhou, China, to assess the deposition fluxes and seasonal variations of phthalate esters (PAEs). Sixteen PAE congeners in bulk deposition samples were measured and the depositional fluxes of ∑16PAEs ranged from 3.41 to 190 μg m?2 day?1, and were highly affected by local anthropogenic activities. The significant relationship between PAEs and particulate depositional fluxes (correlation coefficient R2 = 0.72, P < 0.001) showed PAEs are associated primarily with particles. Temporal flux variations of PAEs were influenced by seasonal changes in meteorological parameters, and the deposition fluxes of PAEs were obviously higher in wet season than in dry season. Diisobutyl phthalate (DiBP), Di-n-butyl phthalate (DnBP), and Di(2-ethylhexyl) phthalate (DEHP) dominated the PAE pattern in bulk depositions, which is consistent with a high consumption of the plasticizer market in China. PAE profiles in bulk deposition showed similarities exhibited in both time and space, and a weak increase of high molecular weight PAE (HMW PAE) contribution in the wet season compared to those in the dry season. Average atmospheric deposition fluxes of PAEs in the present study were significantly higher than those from other studies, reflecting strong anthropogenic inputs as a consequence of rapid industrial and urban development in the region. 相似文献
170.
Yang Zhang X.-Y. Wen C.J. Jang 《Atmospheric environment (Oxford, England : 1994)》2010,44(29):3568-3582
The chemistry–aerosol–cloud–radiation–climate feedbacks are simulated using WRF/Chem over the continental U.S. in January and July 2001. Aerosols can reduce incoming solar radiation by up to ?9% in January and ?16% in July and 2-m temperatures by up to 0.16 °C in January and 0.37 °C in July over most of the continental U.S. The NO2 photolysis rates decrease in July by up to ?8% over the central and eastern U.S. where aerosol concentrations are high but increase by up to 7% over the western U.S. in July and up to 13% over the entire domain in January. Planetary boundary layer (PBL) height reduces by up to ?23% in January and ?24% in July. Temperatures and wind speeds in July in big cities such as Atlanta and New York City reduce at/near surface but increase at higher altitudes. The changes in PBL height, temperatures, and wind speed indicate a more stable atmospheric stability of the PBL and further exacerbate air pollution over areas where air pollution is already severe. Aerosols can increase cloud optical depths in big cities in July, and can lead to 500–5000 cm?3 cloud condensation nuclei (CCN) at a supersaturation of 1% over most land areas and 10–500 cm?3 CCN over ocean in both months with higher values over most areas in July than in January, particularly in the eastern U.S. The total column cloud droplet number concentrations are up to 4.9 × 106 cm?2 in January and up to 11.8 × 106 cm?2 in July, with higher values over regions with high CCN concentrations and sufficient cloud coverage. Aerosols can reduce daily precipitation by up to 1.1 mm day?1 in January and 19.4 mm day?1 in July thus the wet removal rates over most of the land areas due to the formation of small CCNs, but they can increase precipitation over regions with the formation of large/giant CCN. These results indicate potential importance of the aerosol feedbacks and an urgent need for their accurate representations in current atmospheric models to reduce uncertainties associated with climate change predictions. 相似文献