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261.
在考虑经济水平差异的基础上,通过对典型区域的调查确定煨炕活动水平,采用排放因子法建立了兰州市2016年煨炕大气污染物排放清单,煨炕排放的SO_2、NO_x、NH_3、CO、VOCs、PM_(10)、PM_(2.5)、OC和EC的总量分别为340. 8、201. 8、106. 0、36 628. 2、4 997. 2、6 070. 3、5 645. 1、1 089. 3和1 233. 1 t·a~(-1).对污染物排放总量进行时空分配,排放主要集中在11月至次年4月中旬;排放量与区域经济水平密切相关,且存在着明显的空间差异,排放量大的区域主要集中在榆中东南部、永登中部和七里河南部.利用WRF~-Chem模式研究了采暖季煨炕对兰州市PM_(2.5)浓度的平均贡献,引入煨炕污染物排放清单提高了模拟结果的准确性,兰苑宾馆(位于城区)和榆中站(位于农村)的PM_(2.5)平均浓度在模拟期间分别升高了32μg·m~(-3)和34μg·m~(-3),贡献率分别为37. 6%和49. 2%.可见,研究和制定科学的煨炕污染物防控对策对改善区域环境空气质量具有重要意义. 相似文献
262.
环境健康风险评价中我国居民暴露参数探讨 总被引:45,自引:6,他引:45
暴露参数是人体暴露和健康风险评价中的关键性参数,根据我国居民人群的基本体征参数和相关调查统计数据,在借鉴和参考了美国环境保护署(US EPA)建立暴露参数的方法学基础上,探讨了我国居民呼吸、饮食、皮肤等的暴露参数. 结果表明:我国居民呼吸速率为5.71~19.02 m3/d,18岁以下人群各种活动强度下男性和女性的呼吸速率几乎一样,而18~60岁的男性呼吸速率明显大于女性;我国成年人饮食量为1 176.3 g/d,主要食用米、面及其制品,分别占总饮食量的23%和13%;我国成年男性的皮肤表面积为1.697 m2,成年女性为1.531 m2;我国成年男性平均体质量为62.70 kg,成年女性平均体质量为54.40 kg;我国居民的各种暴露参数与美国相差2.5%~33.3%,若在同等条件下参考国外暴露参数开展暴露和健康风险评价可能带来较大的偏差,开展全国范围内系统的暴露参数调查研究工作迫在眉睫. 相似文献
263.
Jiejie Bian Huaqiao Gui Zhibo Xie Tongzhu Yu Xiuli Wei Wenyu Wang Jianguo Liu 《环境科学学报(英文版)》2020,32(4):275-285
In order to realize accurate dynamic control of supersaturation and to study condensation growth characteristics of nanoparticles through different levels of super saturation,a series of parametric analyses and systematic comparisons between two-stage and three-stage operating temperature designs were simulated with COMSOL Multiphysics.The simulation results showed that the three-stage operating temperature did not change peak supersaturation compared with two operating temperatures,and the three-stage operating temperature was superior in decreasing the amount of water vapor and the temperature,thus lowering particle loss and variation in detection and collection.The peak supersaturation level increased by 0.3 as the flow rate increased from 0.6 to 2.0 L/min,but the supersaturation peak moved from 0.0027 z0 to 0.08 z0(i.e.,the growth time and the final size decreased by 40%).Peak supersaturation increased as the temperature difference increased or the temperature difference window was shifting left,and minimum activation size decreased.Shifting the 70℃temperature difference window from 9℃,79℃-1℃,71℃for the condenser and initiator temperatures resulted in peak supersaturation in the centerline being above 5.8,and the activation size changed as low as 1 nm.Experiments with flow rates varying by a factor of 2.5(from 0.6 to 1.5 L/min) resulted in a final size decrease of 43%(from 3.2 to 1.8 μm),and experimental results of outlet particle size distributions were equivalent with theoretical analysis as the operating temperature was changed. 相似文献
264.
A preliminary study on measurements of black carbon in the atmosphere of northwest Qilian Shan 总被引:1,自引:0,他引:1
Black carbon (BC) concentration and meteorological data are measured discontinuously from May 2009 to March 2011, at the Qilian Shan Station of Glaciology and Ecologic Environment (hereafter “QSSGEE”), located near the terminal of the Laohugou No.12 Glacier in northwestern Qilian Shan, China.We measured the daily, monthly and seasonal variations of BC concentration in the atmosphere and discussed the possible emission sources. Black carbon background concentration in this region varied in the range of 18-72 ng/m3 with the highest in summer and the lowest in autumn. The relations between BC concentration and surface wind direction indicated that BC concentration was higher when northwest wind prevails while lower when southeast wind prevails. Air masses backward trajectories showed the potential emission sources in the northwest. Significant positive correlations between daily mean BC concentration and relative humidity indicated that BC might be one of important cloud condensation nuclei. This hypothesis needs to be confirmed further through cloud microphysical features in this region. 相似文献
265.
Monosulfuron-ester is a new, low rate, sulfonylurea herbicide that is being promoted for annual broadleaf and gramineal weed
control; however, there is a lack of published information on its behavior in soils. The adsorption and desorption of monosulfuronester
by seven type soils were measured using a batch equilibrium technique. The results showed that the Freundlich equation fitted
its adsorption and desorption well, and the Freundlich constant values (Kf-ads) ranged from 0.88 to 5.66. Adsorption isotherms were
nonlinear with 1/nf-ads values < 1. Soil pH, organic matter (OM), and clay content were the main factors influencing its adsorption
and desorption. Adsorption and desorption were negatively correlated with pH 4.0–8.0 while positively correlated with OM and clay
content. The adsorption of monosulfuron-ester was mainly a physical process, because its free energy (ΔG) in seven soils was less than
40 kJ/mol. Monosulfuron-ester adsorption by three soils increased with increasing CaCl2 concentration using CaCl2 as a background
electrolyte. Monosulfuron-ester desorption was hysteretic in all tested soils. 相似文献
266.
论炼山对杉木人工林生态系统影响的利弊及对策 总被引:25,自引:2,他引:25
随着杉木人工林面积的不断扩大,杉木人工林地力衰退问题日益严重,而炼山是导致杉木人工林地力衰退的主要原因之一。本文在国家“七五”攻关子课题《炼山对杉木幼林生态系统影响机理及计量评价研究》连续10a定位研究成果的基础上,对国内外有关炼山对采伐剩余物、水土流失、土壤肥力、杉木生长影响等问题进行全面阐述,同时对炼山利弊问题进行归纳与总结,并提出相应对策,这对变革传统杉木经营制度、可持续利用南方山地资源具有重大指导意义。 相似文献
267.
概要地介绍了中文环境科技核心期刊、美国《工程索引》(EI)和《科学引文索引》(SCI)收录中国科研论文的情况,以及两份知名英文环境期刊的论文评审标准。EI和SCI收录其来源期刊中英文摘要符合要求的论文。一篇好英文摘要有助于论文被国际环境期刊录用和增加论文的影响力。基于目前EI及SCI的来源期刊中缺少中文专业期刊,国内的环境科研人员可以先将其重要研发成果陆续在中文环境核心期刊上发表,形成系列文章,然后再融合这些文章,投寄英文国际环境期刊。这个策略可及时将研发成果公开发表,提高论文被国际期刊录用的几率,并增加中文环境核心期刊的知名度和声望。 相似文献
268.
中国对虾血细胞包掩作用的超微结构和组织化学观察 总被引:6,自引:0,他引:6
用鳗弧菌注射中国对虾,对其体内血细胞的包掩作用进行了超微结构和组织化学观察.结果表明:在注菌的对虾体内,包囊产生于多种器官和组织,在释放颗粒的过程中,半颗粒细胞和颗粒细胞的表面即发生变化,开始与周围细胞相粘接;在包囊中心是电子不透明的非结构团块;含吞噬泡的透明细胞也常被包围在包囊内,构成包囊的血细胞中细胞器趋于退化,在组织化学上表现为细胞中的RNA大为减少,色氨酸几乎消失;然而,包囊从开始形成起,就呈Chevrement铁氰化钾法强阳性反应,此反应可被Barnet碘液法封闭.推测这一现象与黑色素生成有关. 相似文献
269.
270.