全文获取类型
收费全文 | 252篇 |
免费 | 32篇 |
国内免费 | 51篇 |
专业分类
安全科学 | 103篇 |
废物处理 | 2篇 |
环保管理 | 44篇 |
综合类 | 136篇 |
基础理论 | 14篇 |
污染及防治 | 21篇 |
评价与监测 | 4篇 |
社会与环境 | 6篇 |
灾害及防治 | 5篇 |
出版年
2023年 | 5篇 |
2022年 | 6篇 |
2021年 | 11篇 |
2020年 | 9篇 |
2019年 | 14篇 |
2018年 | 16篇 |
2017年 | 18篇 |
2016年 | 23篇 |
2015年 | 17篇 |
2014年 | 21篇 |
2013年 | 20篇 |
2012年 | 12篇 |
2011年 | 23篇 |
2010年 | 25篇 |
2009年 | 13篇 |
2008年 | 6篇 |
2007年 | 8篇 |
2006年 | 19篇 |
2005年 | 12篇 |
2004年 | 17篇 |
2003年 | 4篇 |
2002年 | 6篇 |
2001年 | 2篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1988年 | 1篇 |
1977年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有335条查询结果,搜索用时 15 毫秒
161.
中国大部分机动车温室气体排放研究都集中于CO2排放,对于CH4和N2O等排放的研究鲜见. 以中国机动车污染防治年报(2011年)、中国汽车工业年鉴(2011年)、中国统计年鉴(2011年)以及交通运输部发布的相关信息和数据(2011年)等为基础,结合文献调研和2008─2010年对北京、广州等国内10余座典型城市的实地调查结果,获得2010年我国机动车活动水平及排放特征. 基于上述基础信息,解析得到按不同车型、燃料和车龄分布的机动车保有量、年均行驶里程及排放因子,建立2010年中国机动车CH4和N2O排放清单. 结果表明:2010年中国机动车CH4和N2O排放量分别为23.90×104和6.01×104t,折算成CO2分别为501.99×104和1862.51×104t. 不确定性分析则显示,中国CH4排放量在18.21×104~27.52×104t之间,N2O排放量在4.32×104~7.62×104t之间. 在机动车中,汽车CH4和N2O排放量最大,分担率(某车型污染物排放量占机动车排放总量的比例)分别为77.99%和94.22%,而摩托车和农用车排放分担率较小. 在各类汽车中,CH4排放主要来源于轻型汽油车和天然气出租车,二者的排放分担率分别为47.98%和23.42%;N2O排放则主要源于轻型汽油车,其分担率为73.09%. 因此,轻型汽油车是削减机动车CH4和N2O排放的重点车型,同时天然气出租车也应作为控制CH4排放的主要车型. 相似文献
162.
为研究乙醇汽油使用过程中存在的静电风险及带电变化规律,基于自主研发的油品电荷密度表,试验研究了乙醇含量对管输汽油静电带电规律的影响,获得乙醇体积含量0~5%的管输油品静电数据;对油库内乙醇汽油装车作业及加油站加油作业乙醇汽油静电起电特性进行了试验研究。研究结果表明:随着乙醇含量的增加,油品静电呈现先增大后减小的趋势;乙醇体积含量在0.5%~1%时,油品静电起电量最高可达到-77.2 μC/m3,为此需注意乙醇汽油调配过程中可能存在的静电风险;高电导率的车用乙醇汽油在加油作业时,油品静电起电量较低。 相似文献
163.
ABSTRACT: Recent developments in multiple objective decision making methods presented in the upcoming sequence of research papers are evaluated and compared with respect to their usefulness in addressing challenging problems in water resources management. Because many of the decision making techniques originated in the field of operational research, the historical evolution of this field is outlined and the current need for developing a wide range of techniques for employment in strategic decision making is pointed out. Informative attributes for classifying decision making techniques are given to allow a practitioner to select decision aids that can best model the key characteristics of the particular problems under study. By systematically applying a wide variety of multiple objective decision making techniques to many different kinds of water resources problems, the authors of the papers clearly demonstrate the effectiveness of utilizing these methods for assisting in making both tactical and strategic decisions in water resources management. 相似文献
164.
Lalit K. Sinha 《Journal of the American Water Resources Association》1970,6(2):209-221
Step-IB in the first phase of an “Operational Watershed Model” recently initiated by the Central and Southern Florida Flood Control District for managing its water resources is to compute water surface elevation, spatially and temporally, in the Kissimmee River Basin system of reservoirs, channels and spillways. An approach is based upon the principles of gradually varied flow. Mathematical relationships to compute lake stage as a function of storage, and to compute discharge through the control structures as a function of gate opening and differential head across the structures are developed. Their feasibility for application is clearly demonstrated by the simulated mean daily water surface elevation for a period of two years on the tail side of one typical gated spillway and on the head side of another gated spillway. 相似文献
165.
对机动车排气当前的检测方法及其不足之处进行综述,对简易工况法的发展过程进行介绍,同时提出了简易工况法在胶州市推广的思路和对策。 相似文献
166.
阐述了直线电机轨道交通的技术特点,并就其安全评价体系做了介绍,应用ADAMS/Rail软件分别建立了轮对、构架、悬挂系统、止挡、自导向径向转向架、直线电机以及车体的模型,并考虑轮轨关系组合为直线电机轨道交通的车辆-轨道耦合动力学整体模型,进行了大量的计算仿真。笔者主要以脱轨系数为例进行了动力响应分析,给出考虑了径向转向架和直线电机后的安全评判指标,比较了与径向转向架和未安装直线电机的区别,验证了模型的正确性和有效性。为后续研究直线电机轨道交通车辆-轨道耦合动力学模型提供了理论基础,从而可以进一步从安全性角度研究线路设计参数。为我国今后直线电机轨道交通建设就线路参数对车辆运行安全性的影响研究方面起到理论指导作用。 相似文献
167.
168.
169.
机动车业的发展和普及,为人们的生活带来许多方便。但是,随着机动车数量的不断增加,排气污染对城市环境的影响越来越明显。对机动车污染现状的分析,探讨如何控制机动车尾气污染的措施和方法。 相似文献
170.
Jessica H. Mirman Sara J. Seifert Mark R. Zonfrillo Kristi Metzger Dennis R. Durbin Kristy B. Arbogast 《Traffic injury prevention》2015,16(7):S24-S31
Objectives: We explored if an alternative CRS design that utilized a mechanical adjunct to amplify the force applied to the adult seat belt (intervention CRS) results in more accurate and secure attachment between the CRS and the vehicle compared to similar CRS models that use LATCH or the existing adult seat belt. We conducted three separate studies to address this question and additionally explored: (1) the contribution of prior CRS installation experience (Study 1), (2) the value-added of CRS labeling (Study 2), and (3) paper-based vs. video instructions (Study 3).Methods: In Studies 1 and 2 we assessed a forward facing combination CRS design (intervention CRS) compared to a commercially available LATCH equipped model (control CRS) and in Study 3 we conducted a similar study using a convertible model of both the intervention and control CRS. Participants installed both CRS in a contemporary minivan and could choose which type of attachment to use for the control CRS (LATCH or seat belt); order of installation was counter-balanced. Evaluators systematically examined installations for accuracy and security.Results: Study 1: A greater proportion of participants in both the experienced and inexperienced groups was able to securely install the intervention CRS compared to the control CRS: (45% vs. 16%, p =.0001 for experienced) and (37% vs. 6%, p =.003 for inexperienced). No differences between the CRS were observed for accuracy of installation in either user group. Study 2: A greater proportion of participants were able to securely install the enhanced intervention CRS compared to the control CRS: (62% vs. 9%, p =.001). The intervention CRS demonstrated reduced installation accuracy: (30% vs. 61%, p =.001). Study 3: A greater proportion of participants was able to securely install the intervention CRS compared to the control CRS: 79% vs. 66% p =.03, but this effect was smaller than in the previous studies. Participants were less likely to achieve an accurate installation with the intervention CRS compared to the control CRS: 54% vs. 79%, p =.004. Common accuracy errors in each study included twisting or misrouting the seatbelt when installing the intervention CRS.Conclusions: Our results suggest that novel CRS designs that utilize mechanical advantage to facilitate attachment of the CRS to the vehicle result in a tighter installation compared to LATCH equipped models, but an increase in accuracy errors occurred. 相似文献