全文获取类型
收费全文 | 5851篇 |
免费 | 739篇 |
国内免费 | 746篇 |
专业分类
安全科学 | 1896篇 |
废物处理 | 463篇 |
环保管理 | 833篇 |
综合类 | 2558篇 |
基础理论 | 325篇 |
环境理论 | 7篇 |
污染及防治 | 507篇 |
评价与监测 | 373篇 |
社会与环境 | 130篇 |
灾害及防治 | 244篇 |
出版年
2024年 | 13篇 |
2023年 | 89篇 |
2022年 | 151篇 |
2021年 | 217篇 |
2020年 | 235篇 |
2019年 | 208篇 |
2018年 | 160篇 |
2017年 | 244篇 |
2016年 | 270篇 |
2015年 | 321篇 |
2014年 | 302篇 |
2013年 | 415篇 |
2012年 | 509篇 |
2011年 | 485篇 |
2010年 | 345篇 |
2009年 | 372篇 |
2008年 | 246篇 |
2007年 | 378篇 |
2006年 | 374篇 |
2005年 | 274篇 |
2004年 | 207篇 |
2003年 | 235篇 |
2002年 | 192篇 |
2001年 | 170篇 |
2000年 | 158篇 |
1999年 | 117篇 |
1998年 | 109篇 |
1997年 | 108篇 |
1996年 | 120篇 |
1995年 | 85篇 |
1994年 | 53篇 |
1993年 | 49篇 |
1992年 | 38篇 |
1991年 | 21篇 |
1990年 | 22篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有7336条查询结果,搜索用时 15 毫秒
931.
The current modified electro-Fenton system was designed to develop a more convenient and e cient undivided system for practical
wastewater treatment. The system adopted a cathode portion that employed magnetic stirring instead of common oxygen gas di usion
or gas sparging to supply oxygen gas for the electrolyte solution. Key factors influencing the cathode fabrication and activity
were investigated. The degradation of acid fuchsine with a self-made graphite-polytetrafluorethylene cathode was studied using a
spectrophotometer. It was found that the cathode generated hydrogen peroxide with high current e ciency and the hydrogen peroxide
yield of the cathode did not decay after 10 times reuse. With the Pt anode at a ferrous ion concentration of 0.5 mmol/L, a pH of 3, and
using magnetic stirring, dye decolorization could be rapidly accomplished but the destruction of benzene rings and intermediates was
fairly di cult. With a Fe anode, dye degradation was more complete. 相似文献
932.
Activated carbon (AC) was considered to be an effective sorbent to control mercury in combustion systems. However, its capture
capacity was low and it required a high carbon-to-mercury mass ratio. AC loaded with catalyst showed a high elemental mercury (Hg0)
capture capacity due to large surface area of AC and high oxidization ability of catalyst. In this study, several metal chlorides and metal
oxides were used to promote the sorption capacity of AC. As a result, metal chlorides were better than metal oxides loaded on AC
to remove gaseous mercury. X-ray diffractometer (XRD), thermogravimetric analyzer (TGA) and specific surface area by Brunauer-
Emmett-Teller method (BET) analysis showed the main mechanisms: first, AC had an enormous surface area for loading enough
MClx; second, Cl and MxOy were generated during pyrogenation of MClx; finally, there were lots of active elements such as Cl and
MxOy which could react with elemental mercury and convert it to mercury oxide and mercury chloride. The HgO and HgCl2 might be
released from AC’s porous structure by thermo regeneration. A catalytic chemisorption mechanism predominates the sorption process
of elemental mercury. As Co and Mn were valence variable metal elements, their catalytic effect on Hg0 oxidization may accelerate
both oxidation and halogenation of Hg0. The sorbents loaded with metal chlorides possessed a synergistic function of catalytic effect
of valence variable metal and chlorine oxidation. 相似文献
933.
本文研究了富集柱类型、富集温度和色谱操作条件等因素对二次富集气相色谱法测定环境中痕量PH3的影响,并将其应用于青岛大气和东海陆架沉积物中PH3的测定,取得了较为满意的结果.该方法具有操作简单、灵敏度高、分析速度快、干扰少等优点,其检测限为0.02 pg、精密度2.0%、线性范围为0.56 pg~5.6 ng.用此方法测定了冬季东海大陆架表层沉积物中PH3含量为(0.51~23.10)×10-9,其分布明显受到人类活动的影响,研究结果还表明东海沉积物中的PH3是海洋中磷的潜在来源之一;青岛崂山大气中PH3日变化趋势说明大气中PH3明显受光照的影响. 相似文献
934.
曲健 《辽宁城乡环境科技》2009,(2):33-35
利用固相萃取法提取变压器油中的多氯联苯,采用浓硫酸净化、气相色谱法进行分析,根据峰型和保留时间,以多氯联苯的商业用混合物的形式进行定性、定量,可以定量检出变压器油中2mg/kg以下的多氯联苯。 相似文献
935.
936.
西部管道工程HSE一体化绩效管理应用研究 总被引:1,自引:0,他引:1
分析了我国管道工程项目HSE绩效管理存在问题,运用绩效管理理论,结合“PMT(业主)+PMC(监理)+EPC(施工总承包方)”一体化模式及西部管道工程,阐述了HSE一体化绩效管理体系的建立及应用情况。 相似文献
937.
Pressurized gas pipelines may be endangered by accidental or intentional activities causing excess ground vibrations leading to failure. Thus, many papers have been published on this issue, yet most of these efforts suffer from complexity and inability to ascertain that all engaged factors are taken into account. These factors are attributed, namely, to explosion source, explosion-ground interaction, energy transfer through the ground, ground-pipeline interaction, and response of the pipeline. The deterministic method developed previously by the author has derived useful prediction mathematical formulas that can be used to calculate, either the stand-off distance of purposefully used explosives, or the maximum quantity of explosives to be used at a given distance, or the equivalent stress of a pipeline induced by an explosive charge at a given standoff distance. The method can also be applied to accidental blast events in factories or other activities. Yet, the complex formulas developed are hard to be used in the field and a simpler approach is needed to facilitate and accelerate in-field estimations. Thus, a nomogram was prepared to make the safety estimations easy and fast and taking into account all engaged critical factors starting from the explosion source through the integrity of the structure. 相似文献
938.
To solve the problems of the difficulty in early leakage monitoring and larger positioning error for urban hazardous chemicals pipelines, the optimized method based on the improved Inverse Transient Analysis (ITA) and Ant Lion Optimizer (ALO) was proposed. Firstly, based on the obtained experiment's results of leakage of natural gas in the non-metallic pipeline, the segment classification method was incorporated into the pressure gradient calculation. The modified method can adapt to the multi-node characteristics of urban pipe networks and help to obtain the preliminary positioning calculation results after optimization. Then the calculation results were embedded in the ITA calculation model. The input parameters of the gas pipeline such as boundary conditions, leakage rate and friction coefficient were used to establish the characteristic linear equations. Then the objective function of the least-squares criterion was defined, and the improved ITA model suitable for leakage detection of urban natural gas pipeline networks was constructed. Finally, the ALO was used to optimize the calculation process of the improved ITA model, and iteratively optimize the optimal friction coefficient and its corresponding minimum objective function (OF) value. As a result, a more precise location of the leakage source was calculated. The validation of the modified method is conducted by comparing the calculated values with the experiment's results. The results show that the method can accurately predict the location where the pipeline leakage occurs. The minimum error is 3.17%. Compared with the traditional ITA, this method not only accelerates the convergence speed of the objective function, but also improves the accuracy of location calculation. 相似文献
939.
为研究三元锂离子电池在空运低压环境中的安全性,通过自主设计搭建的封闭式变压实验舱开展相关实验,对不同荷电状态(SOC)下的三元锂离子电池在不同压力环境(101,80,60,40 kPa)下的热失控特性进行研究,采集电池热失控过程中的温度以及实验舱内的压力变化,并对热失控后实验舱内的气体成分进行分析。结果表明:三元锂离子电池热稳定性随着SOC的升高而下降,常压下100%SOC的电池热失控温度可达650.8 ℃,初始环境压力越低,相同SOC的电池热失控最高温度越低。随着环境压力的降低,相同SOC的电池在热失控后会生成更多CO,且电解液占比升高。研究结果可为锂离子电池空运安全性研究提供理论依据。 相似文献
940.
为提高闸阀可靠度计算准确性,将模糊准则引入闸阀可靠性设计,将闸阀应力与阀体通径、内压之间隐式关系显式化,并基于神经网络构建地震工况下闸阀数学模型;利用蒙特卡洛法,计算闸阀在常规方法下的可靠度;利用正态型隶属函数描述闸阀强度的模糊性,计算闸阀在考虑模糊强度时的可靠度;对比强度的模糊性对可靠度计算结果的影响,分析不同隶属函数下的闸阀模糊可靠度。与传统随机可靠度计算方法相比,该方法对不确定性描述更合理,理论上对可靠度的计算更加准确。 相似文献