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861.
污水处理厂由于运行过程能够大量释放温室气体CO2、CH4和N2O而受到广泛关注. 本文概括了3种温室气体在污水处理过程中的产生机理,比较了国内外多种实际处理工艺的温室气体产生因子,并对其产生量的主要影响因素进行了分析,以期能为相关领域的研究人员提供参考.  相似文献   
862.
磷酸三(1,3-二氯-2-丙基)酯(TDCPP)在环境介质及生物样本中被广泛检出,为探究TDCPP的潜在神经毒性以及作用机制,以C57BL/6小鼠为动物模型,考察经300 mg·kg-1·d-1的TDCPP持续染毒35 d后,小鼠大脑皮层神经功能相关因子及血清代谢组学的变化。结果显示,小鼠在TDCPP染毒35 d后,大脑皮层中5-羟色胺(5-HT)含量和乙酰胆碱酯酶(AChE)活性无显著变化(P>0.05),而促炎性细胞因子白细胞介素-6(IL-6)、白细胞介素-1βIL-1β)、肿瘤坏死因子-αTNF-α)、诱导型一氧化氮合酶(iNOS)及胶质细胞源性神经营养因子(GDNF)基因表达水平显著上调(P<0.05),神经营养因子-3(Ntf3)基因表达水平显著下调(P<0.05);同时,TDCPP染毒显著干扰了小鼠的代谢过程,引起异亮氨酸、谷氨酸、甘氨酸和β-葡萄糖等多种神经性疾病相关生物标志物的改变,以及氨基酸代谢、糖类代谢和脂质代谢紊乱。研究结果表明,TDCPP的神经毒性效应与神经炎症和神经元损伤相关因子转录水平改变,以及代谢失衡引起的信号紊乱有关。  相似文献   
863.
本文提出了用GC-ECD测定麦田土壤、植株、麦粒中残留禾草灵的方法。禾草灵残留量用外标法根据峰面积定量。土壤、干麦叶、鲜麦叶和麦粒中的最低检测浓度分别为:0.015ppm、0.029ppm、0.036ppm和0.015ppm。不同样品在0.029—0.087ppm间分别以三个不同浓度标准溶液添加后,全过程回收率试验在75.1%—97.2%之间。  相似文献   
864.
Inshore and offshore populations ofSclerasterias mollis (Hutton, 1872) were sampled on the outer continental shelf off the Otago Peninsula, New Zealand, and their nutritional and reproductive cycles are described from 1985–1986. Histological changes in the gonads are generally typical of other asteroids. The gametogenic cycle takes 12 mo. The gonad and pyloric caeca indices in both females and males had an inverse relationship.S. mollis accumulates nutrients in the pyloric caeca during summer and early autumn. The gonads develop in the autumn and winter. Offshore seastars were much larger and had significantly higher gonad and pyloric caeca indices than inshore individuals. These differences in body sizes and organ indices arise from differences in food availability and/or population density.  相似文献   
865.
对渤海中部油气开采区表层沉积物中的石油烃含量进行了环境质量评价,分析了正构烷烃和多环芳烃分子组成特征,并对其来源进行了解析.结果表明,石油类浓度为12.5-860 μg·g-1之间,污染指数为0.61-41.97;随着与采油平台距离的增加,平台周边海域石油烃含量和污染水平呈现降低的趋势;沉积物沉积时为缺氧还原的沉积环境.正构烷烃的分布特征和甾萜烷生物标志化合物表明,源自大陆高等植物和海洋浮游生物的烷烃共存于渤海近代沉积物中,石油类产品和化石燃料燃烧产物对其贡献不能忽视;石油平台站位PAHs主要来自石油的直接输入,其它站位主要来自燃烧源.  相似文献   
866.
    
Faced with ever‐severe gold mineral depletion, obtaining a sustainable gold resource by utilization of accumulating waste electrical and electronic equipment (WEEE) is of vital importance. Inspired by fischesserite, the first naturally occurring selenide of gold, a novel selenium‐containing polyurethane (Se‐polyurethane) is prepared. This material is able to extract aqueous gold in its elemental form with a selectivity 437 times over Cu2+ and 443 times over Ni2+ and a capacity of 802 mg gold g‐1. The extracted gold can be collected through a noncalcination post‐treatment procedure and the Se‐polyurethane can be recycled via a convenient regeneration procedure. Derived from this material, a high‐throughput circulating aqueous gold mining system and a crosslinked Se‐sponge are illustrated to mimic dynamic and static extraction processes, respectively for possible industrialization. These selenium‐containing materials have the potential to be a useful tool in gold extraction to help prevent future resource depletion.  相似文献   
867.
    
• The long-period groundwater evolution was identified by hydrochemical signatures. • The dominant processes in the groundwater evolution were verified. • Groundwater quality in the coastal areas was susceptible to deterioration due to SI. • Groundwater contamination arose from fertilizer, livestock manure & domestic sewage. The evolution of hydrochemical compositions influenced by long-period interactions between groundwater and the geo-environment is a fundamental issue for exploring groundwater quality and vulnerability. This study systematically investigated the hydrochemical processes and anthropogenic interference occurring in the river basin by bivariate plots, Gibbs diagrams, saturation index, and the major ions ratios. Apparent changes in groundwater hydrochemistry have been observed in the study area, illustrating the origins of major ions are affected by various internal and external factors. Results highlighted that TDS varied from freshwater to brackish water, ranging between 187.90 and 2294.81 mg/L. Ca2+ and HCO3 are the dominant ions in the studied samples. The results gained by Gibbs diagrams, bivariate plots, saturation index, and the major ions ratios demonstrated that minerals dissolution/precipitation, cation exchange, and human inputs play crucial roles in the unconfined aquifers. Moreover, the overuse of nitrogen fertilizer, livestock manure, and industrial/domestic sewage led to nitrate and nitrite contamination and brought significant challenges to the surrounding hydrogeo-environment. The present study could make an unambiguous identification of natural processes and anthropogenic interventions influencing groundwater hydrochemistry’s long-period evolution and create a preliminary strategy for groundwater resources management.  相似文献   
868.
本文回顾了我国自然保护区建设发展状况,对自然保护区管理中存在的一些问题进行了分析,并论述中国自然保护区管理决策支持系统(NRMDSS)在自然保护区管理中的地位、作用和意义,探讨NRMDSS的系统结构、功能。  相似文献   
869.
    
Estimated anthropogenic Hg emission was 11.9 tons in Pearl River Delta for 2014. Quantifying contributions of emission sources helps to provide control strategies. More attentions should be paid to Hg deposition around the large point sources. Power plant, industrial source and waste incinerator were priorities for control. A coordinated regional Hg emission control was important for controlling pollution. We used CMAQ-Hg to simulate mercury pollution and identify main sources in the Pearl River Delta (PRD) with updated local emission inventory and latest regional and global emissions. The total anthropogenic mercury emissions in the PRD for 2014 were 11,939.6 kg. Power plants and industrial boilers were dominant sectors, responsible for 29.4 and 22.7%. We first compared model predictions and observations and the results showed a good performance. Then five scenarios with power plants (PP), municipal solid waste incineration (MSWI), industrial point sources (IP), natural sources (NAT), and boundary conditions (BCs) zeroed out separately were simulated and compared with the base case. BCs was responsible for over 30% of annual average mercury concentration and total deposition while NAT contributed around 15%. Among the anthropogenic sources, IP (22.9%) was dominant with a contribution over 20.0% and PP (18.9%) and MSWI (11.2%) ranked second and third. Results also showed that power plants were the most important emission sources in the central PRD, where the ultra-low emission for thermal power units need to be strengthened. In the northern and western PRD, cement and metal productions were priorities for mercury control. The fast growth of municipal solid waste incineration were also a key factor in the core areas. In addition, a coordinated regional mercury emission control was important for effectively controlling pollution. In the future, mercury emissions will decrease as control measures are strengthened, more attention should be paid to mercury deposition around the large point sources as high levels of pollution are observed.  相似文献   
870.
氟摄入过低或过高,都会对人体健康产生负面影响,此外,水体中的氟化物含量过高也会对水生生物产生危害.本文综述了氟化物的主要来源与分布,以及氟化物的毒性效应,从保护人体健康和水生生物2个角度分析了国内外氟化物水质基准/标准研究现状,并针对氟化物人体健康效应的双阈值性、氟化物摄入源地区差异性、氟化物水生生物毒性受温度、硬度和氯离子浓度等影响的特征,展望了我国氟化物水质基准研究和标准修订的未来发展方向:(1)深入探讨氟化物保护人体健康的最适区间;(2)将氟化物总摄入量的地区差异性纳入地方性水质标准制定的考虑范畴;(3)加强水质参数(如硬度、温度和氯离子浓度等)修正的氟化物水生生物水质基准研究.  相似文献   
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