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排序方式: 共有768条查询结果,搜索用时 921 毫秒
601.
602.
富里酸在水体多环芳烃光化学降解中的作用 总被引:4,自引:1,他引:3
以氙灯作为模拟光源,对水相中5种不同来源、不同浓度富里酸(FA)在5种PAHs光解中的作用进行了比较分析;并通过活性氧的捕获探讨了FA在PAHs光解中的作用.结果表明,不同来源FA的结构及其对PAHs光解的影响具有较高的一致性.在低浓度(1.25 mg·L-1)体系中FA对二氢苊、芴、菲的光解表现出不同程度的抑制作用,而对荧蒽和芘的光解则表现出一定的促进作用;随着体系中FA浓度的升高,其对PAHs的光解总体上呈抑制趋势.FA的存在一方面促进了单线态氧和羟基自由基的生成,强化了PAHs的活性氧光解进程;另一方面FA也可以参与PAHs分子的能量竞争. 相似文献
603.
Alloy dust generated from automobile wheel hub grinding, after entering the wet dust collector, will react with water to produce hydrogen, thus exposing the entire ventilation and dust removal system to potential hydrogen explosion. In this paper, the inhibition mechanism and kinetic characteristics of different concentrations of L-Aspartic acid (L-Asp) on the reaction of Al0.9Mg0.1 alloy with water were studied with respect to adsorption morphology, chemical kinetic modeling and molecular dynamics (MD), using L-Asp as the environmentally-safe hydrogen inhibitor. The results show that within a given temperature interval, the hydrogen production rate of Al0.9Mg0.1 alloy dust decreases with increasing L-Asp concentration. When the L-Asp concentration exceeds 1.0g/L, the hydrogen evolution rate is almost zero. The calculated results of chemical kinetics agree with the Langmuir adsorption model, confirming that L-Asp is an ideal monolayer physical adsorption system on the surface of alloy particles. The FTIR and MD simulation results show that –NH2 and –COOH groups in L-Asp molecules contribute greatly to the adsorption. The research results of this paper can help fundamentally avoid hydrogen generation in wet dust collectors and guarantee intrinsic safety. 相似文献
604.
Sayaka Ono Haruto Sasaki Hitoshi Kumon Yoshitaka Fuwamoto Shunsuke Kondo Takuji Narumi 《Traffic injury prevention》2019,20(4):S152-S156
AbstractObjective: The handover of vehicle control from automated to manual operation is a critical aspect of interaction between drivers and automated driving systems (ADS). In some cases, it is possible that the ADS may fail to detect an object. In this event, the driver must be aware of the situation and resume control of the vehicle without assistance from the system. Consequently, the driver must fulfill the following 2 main roles while driving: (1) monitor the vehicle trajectory and surrounding traffic environment and (2) actively take over vehicle control if the driver identifies a potential issue along the trajectory. An effective human–machine interface (HMI) is required that enables the driver to fulfill these roles. This article proposes an HMI that constantly indicates the future position of the vehicle.Methods: This research used the Toyota Dynamic Driving Simulator to evaluate the effect of the proposed HMI and compares the proposed HMI with an HMI that notifies the driver when the vehicle trajectory changes. A total of 48 test subjects were divided into 2 groups of 24: One group used the HMI that constantly indicated the future position of the vehicle and the other group used the HMI that provided information when the vehicle trajectory changed.The following instructions were given to the test subjects: (1) to not hold the steering wheel and to allow the vehicle to drive itself, (2) to constantly monitor the surrounding traffic environment because the functions of the ADS are limited, and (3) to take over driving if necessary.The driving simulator experiments were composed of an initial 10-min acclimatization period and a 10-min evaluation period. Approximately 10?min after the start of the evaluation period, a scenario occurred in which the ADS failed to detect an object on the vehicle trajectory, potentially resulting in a collision if the driver did not actively take over control and manually avoid the object.Results: The collision avoidance rate of the HMI that constantly indicated the future position of the vehicle was higher than that of the HMI that notified the driver of trajectory changes, χ2 = 6.38, P < .05. The steering wheel hands-on and steering override timings were also faster with the proposed HMI (t test; P < .05).Conclusions: This research confirmed that constantly indicating the position of the vehicle several seconds in the future facilitates active driver intervention when an ADS is in operation. 相似文献
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606.
采用颗粒活性炭(GAC)以共沉淀和热分解法制备了改性活性炭(MnO_2-AC),并采用SEM、XRD表征手段对改性前后活性炭进行微观分析;进而研究了GAC和MnO_2-AC随染料初始浓度、活性碳投加量、温度、吸附时间变化对染料废水罗丹明B的吸附效果影响。结果表明:GAC经改性后,活性炭表面变得粗糙,并有MnO_2产生。在MnO_2-AC投加量为0.2 g,罗丹明B浓度为100 mg/L,温度为25℃条件下反应12 h,其吸附量达到36.80 mg/g。另外,MnO_2-AC对罗丹明B的吸附过程符合Langmuir等温模型,并遵循准二级动力学模型。 相似文献
607.
分别从样品前处理和分析测定两方面对大气细粒子中阳离子表面有机活性物质的二硫蓝分光光度分析法进行优化,并采用优化方案对北京市大气细粒子进行了分析.结果表明:① 优化的最佳样品前处理条件中超声提取频率为40 Hz、初始水浴温度为30℃、超声提取时间为30 min;② 优化的最佳分析测定条件中二硫蓝使用量为1.29 mg(0.5 mL的2.58 g/L二硫蓝溶液)、最佳静置时间为30 min、醋酸盐缓冲液(pH为5)最佳使用量为3 mL.二硫蓝分光光度法优化方案标准曲线的R2为0.9986,线性较好.采用该优化方案测得的北京市大气细粒子中阳离子表面有机活性物质浓度的平均值为12.87 pmol/m3,其浓度水平数量级是阴离子表面有机活性物质的1/10,其浓度水平高于英国诺威奇与爱丁堡,但低于马来西亚吉隆坡. 相似文献
608.
通过热聚合的方法使氮化碳(CN)与Ag/AgI/γ-Al_2O_3发生耦合作用,制备出CN-Ag/AgI/γ-Al_2O_3可见光催化剂.采用X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)和紫外可见漫反射光谱(UV-vis DRS)等方法对合成的样品进行了表征,并通过可见光下甲基橙(MO)的降解实验探究了CN对Ag/AgI/γ-Al_2O_3光催化活性及稳定性的影响.结果表明,CN的掺杂改变了Ag纳米颗粒的形状与粒径,且Ag、AgI与CN之间形成强相互作用.与Ag/AgI/γ-Al_2O_3相比较,在可见光波长分别为λ420、450和510 nm时,CN-Ag/AgI/γ-Al_2O_3对MO具有更高的催化降解效率,光反应30 min后,MO的去除率分别为97%、97%和93%.同时,CN的加入显著地增加了Ag/AgI/γ-Al_2O_3的稳定性,抑制了反应过程中Ag~+的释放量,而且反应前后CN-Ag/AgI/γ-Al_2O_3样品的结构没有明显的变化.其活性和稳定性提高的主要原因是CN加速了电子由MO传递至Ag纳米颗粒的过程,同时Ag颗粒等离子体共振(plasmon)效应的增强也有利于MO的催化降解.不同自由基捕获剂的影响实验表明,O_2~(·-)和h~+是反应体系的主要活性物种. 相似文献
609.
本文根据我国现代火山所处的地质构造环境,将其划分为四种构造类型,即环太平洋火山、陆缘火山、碰撞带火山和大陆板内火山。分析了我国现代火山在时间上的活动特点.喷发频率、火山喷发类型及其现代活动表现。提出了我同现代火山活动监测研究方向。 相似文献
610.