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81.
污染物在环境中普遍以混合物的形式存在,其累积毒性与毒性相互作用具有潜在的环境风险。因此,本研究以水环境中普遍存在的氨基糖苷类抗生素(硫酸链霉素、硫酸安普霉素和双氢链霉素)和重金属锌(Zn)为目标污染物,以蛋白核小球藻(Chlorella pyrenoidosa,C. pyrenoidosa)为指示生物,应用直接均分射线法设计3种抗生素与Zn的3个二元混合物体系,应用时间毒性微板分析法系统测定3种抗生素和重金属Zn及其二元混合物射线的时间-浓度-毒性数据,以浓度加和(concentration addition,CA)与独立作用(independent action,IA)为标准加和参考模型,分析混合物毒性相互作用及其随时间变化规律。结果表明,随着暴露时间延长,3种抗生素和重金属Zn对C. pyrenoidosa的毒性逐渐增强; 2种模型对3个二元混合物体系的毒性相互作用评估基本一致,即在低浓度区域始终呈现加和作用,而在高浓度区域随暴露时间延长由协同作用逐渐转变为加和作用;而对于同一混合物体系,CA和IA模型预测毒性之间的差距随着浓度增加而增加,且IA预测曲线始终位于CA预测曲线上方,显示了IA模型在评估具有相异组分混合物的毒性时较CA模型接近实际观测值。 相似文献
82.
抗赖氨酸加苏氨酸的玉米种子蛋白突变体 总被引:6,自引:0,他引:6
通过离体选择抗赖氨酸加苏氨酸玉米突变体,不仅获得了积累游离苏氨酸和赖氨酸等氨基酸的突变类型,也选择到了种子蛋白组份发生改变的高蛋氨酸突变体和高赖氨酸体细胞无性系变异体。高蛋氨酸种子中总蛋氨酸的含量比对照增高22.6%,这是由于醇溶蛋白Zein-2部分及其蛋氨酸含量增高所致。高赖氨酸变异体种子游离必需氨基酸增高显著(2-10倍),总赖氨酸比对照亲本增高28.1%,含量约占种子干重的0.40%,种子蛋白清蛋白、球蛋白和谷蛋白组份含量增高而醇溶蛋白减少。高赖氨酸和高蛋氨酸特性遗传稳定,植株育性正常。 相似文献
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87.
Heavy metal contamination of road-deposited sediments in a medium size city of China 总被引:2,自引:0,他引:2
The aim of this paper is to determine and compare the environmental factors controlling vertical colonisation of periphyton on Sparganium erectum in a shallow eutrophic turbid lake, Manyas Lake, and an oligo-mesotrophic deep lake, Sapanca Lake, Turkey during the July 1997--November 1998. To investigate the effect of the environmental factors on periphyton colonization on S. erectum, the stem was cut above the rhizomes and subdivided into three equal sections. Multivariate statistical analyses have been applied to clarify relationships between environmental variables and periphyton colonization on S. erectum. Results indicated that physical disturbance and trophic level of the lakes influenced the colonization of the periphyton. Among the measured parameters, low light intensity, total suspended solids, temperature and water level fluctuation were observed as driving factors in Manyas Lake whereas nutrient deficiency was found as key factor in Sapanca Lake. The zonation of the periphyton, density, composition and dominant/subdominant taxa were significantly different in these lakes. However, Oedogonium sp., Mougeotia sp., Cylindrocapsa sp., Cladophora glomerata (Linn.), Aulacoseira italica (Ehr.) Simonsen, Melosira varians C. Agardh, Navicula tripunctata (O.F. Müller) Bory and Fragilaria ulna (Nitzsch) Lange-Bertalot were found as dominant species at all sections of S. erectum both in Manyas Lake and Sapanca Lake. It can be thought that these species have a broad range of tolerance to several physical, chemical and hydrologic disturbances. This is the first study to introduce how much the water quality and hydrologic drivers have affected vertical colonization of periphyton on S. erectum in two lakes with different mixing regimes. 相似文献
88.
Chlorobenzenes and organochlorinated pesticides in vegetable soils from an industrial site, China 总被引:1,自引:0,他引:1
Organochlorinated compounds are ubiquitous contaminants in the environment, especially in industrial sites. The objective of the work was to investigate whether a vegetable field near an industrial site is safe for vegetable production. The residues of chlorobenzenes (CBs), hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in a vegetable field which was near a chemical plant in China were characterized. Point estimate quotient was used for ecological risk assessment of the investigated site. The results showed that all CBs except monochlorobenzene (MCB) were detected in soils. The total concentrations of ∑CBs ranged from 71.06 to 716.57 ng/g, with a mean concentration of 434.93 ng/g. The main components of CBs in soil samples were dichlorobenzenes (DCBs), trichlorobenzenes (TCBs) and tetrachlorobenzenes (TeCBs), while for single congeners, 1,2,4-TCB had the highest concentration, which ranged from 13.21 to 210.35 ng/g with a mean concentration of 111.89 ng/g. Residues of hexachlorobenzene (HCB) in soil samples ranged from 0.9 to 11.79 ng/g, significantly lower than ∑DCB, ∑TCB and ∑TeCB. Concentrations of ∑HCHs and ∑DDTs in soils ranged from 11.32 to 55.24 ng/g and from 195.63 to 465.58 ng/g, respectively, of which the main components were αup-HCH and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE). Ecological risk assessment for the investigated site showed that the most potential risks were from TCBs and TeCBs, based on the hazard quotients. The higher residues of CBs and DDTs compared to the target values and the higher than 1 hazard quotients indicated that this area is not safe for vegetable production and thus soil remediation is needed. 相似文献
89.
磁化处理对活性污泥胶体颗粒表面的zeta电位的影响 总被引:1,自引:0,他引:1
污水处理过程中,二沉池的泥水分离影响整套工艺的效果,用投加混凝剂来降低活性污泥胶体颗粒表面的zeta电位(以下简写活性污泥zeta电位),增加了运行成本.通过磁场磁化可以降低活性污泥zeta电位,达到节省药剂的目的.研究了磁感应强度、磁化时间、磁场位型以及搅拌速率对氧化沟活性污泥zeta电位的影响规律.研究表明,磁化处理能降低活性污泥zeta电位,在磁场中心磁感应强度为0.40 T左右及反应器与磁场平行静置磁化时,zeta电位降低幅度最大,平均在46.5%~51.4%. 相似文献
90.
影响省级环境监测中心站职工积极性因素的调查 总被引:1,自引:1,他引:0
调查结果表明,在二十项调查内容中,省环境监测站职工普遍对工作条件类指标(单位的领导水平、良好的工作环境、和睦的人际关系、领导重视和单位的前途)寄予很高的期望。对经济类指标(福利待遇和稳定的经济收入)反映强烈。此外,对能够体现知识分子能力和水平的职称晋级问题也有较高的要求 相似文献