首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   99篇
  免费   17篇
  国内免费   10篇
安全科学   38篇
废物处理   1篇
环保管理   16篇
综合类   45篇
基础理论   8篇
污染及防治   9篇
评价与监测   5篇
社会与环境   2篇
灾害及防治   2篇
  2023年   1篇
  2020年   2篇
  2019年   5篇
  2018年   5篇
  2017年   8篇
  2016年   5篇
  2015年   6篇
  2014年   4篇
  2013年   8篇
  2012年   6篇
  2011年   11篇
  2010年   6篇
  2009年   9篇
  2007年   5篇
  2006年   4篇
  2005年   5篇
  2004年   2篇
  2003年   6篇
  2002年   7篇
  2001年   3篇
  2000年   5篇
  1999年   2篇
  1998年   3篇
  1997年   3篇
  1996年   1篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1990年   1篇
排序方式: 共有126条查询结果,搜索用时 93 毫秒
101.
应用膜生物反应器处理药酒废水的启动试验初探   总被引:4,自引:1,他引:3  
为了推广膜生物反应器在实际工程中的应用,对平板式膜生物反应器处理药酒厂废水时的启动方式展开探讨。试验采用了三种方式,结果表明通过膜出水,逐渐提高容积负荷的方式,不仅启动最快,而且膜污染较轻,是一种简洁、可行的启动方式。  相似文献   
102.
目的解决中重型车辆装备在高原高寒环境下蓄电池充放电性能降低,起动电量供应不足的问题。方法采用燃油空气加热器对车用铅酸蓄电池进行加热,同时运用专用保温箱进行保温,保持蓄电池内部温度在正常工作范围,确保其在低温环境下的充放电性能。结果使用蓄电池加热和保温装置,可将蓄电池电解液温度升至常温。在-25℃环境条件下,可以提高蓄电池放电量65%左右;在-41℃环境条件下,可以提高蓄电池放电量110%左右。结论蓄电池加热和保温装置可以有效提高其低温环境下充放电性能,使车用蓄电池在低温环境中可以有效提供发动机起动及各种起动辅助装置用电,为高原高寒地域中重型车辆的起动与运行提供有效保障。  相似文献   
103.
目前炼油企业在加工高含硫原油的必然趋势下,为实现装置安全、平稳、长周期运行,有计划地提高设备级别、更换旧设备成为当务之急;合理利用旧设备,降低安全隐患,充分挖掘现有资源,是企业降耗增效的有效措施.针对2001年下线的18台浮头式换热器再用技术,进行了两种结构改制对比,提出了一种切实可行的改造方案.  相似文献   
104.
针对厚壁半球形封头的拉深成形,将板坯分成4个区域,根据每个区域的应力分布特点,对每个区域的壁厚变化规律做了理论上的推导与计算,并将理论计算值同有限元模拟结果比较,得到了很好的效果.  相似文献   
105.
氧化沟的水力计算   总被引:5,自引:2,他引:5  
赵星明 《环境工程》2000,18(2):14-17
阐述了氧化沟进水流量、循环流量和断面平均流速的关系 ,分析了沟内平均流速所起的作用及调节方法 ;分析了提升水头与水头损失的关系 ,给出了它们的计算方法 ;对弯道导流板的作用进行了剖析 ,提出了导流板偏置可以减少导流板的数量 ,降低弯道摩阻 ,并可以避免弯道隔墙背流处的固体沉淀。  相似文献   
106.
Objective: In previous research, a tool chain to simulate vehicle–pedestrian accidents from ordinary driving state to in-crash has been developed. This tool chain allows for injury criteria-based, vehicle-specific (geometry, stiffness, active safety systems, etc.) assessments. Due to the complex nature of the included finite element analysis (FEA) models, calculation times are very high. This is a major drawback for using FEA models in large-scale effectiveness assessment studies. Therefore, fast calculating surrogate models to approximate the relevant injury criteria as a function of pedestrian vehicle collision constellations have to be developed.

Method: The development of surrogate models for head and leg injury criteria to overcome the problem of long calculation times while preserving high detail level of results for effectiveness analysis is shown in this article. These surrogate models are then used in the tool chain as time-efficient replacements for the FEA model to approximate the injury criteria values. The method consists of the following steps: Selection of suitable training data sets out of a large number of given collision constellations, detailed FEA calculations with the training data sets as input, and training of the surrogate models with the FEA model's input and output values.

Results: A separate surrogate model was created for each injury criterion, consisting of a response surface that maps the input parameters (i.e., leg impactor position and velocity) to the output value. In addition, a performance test comparing surrogate model predictions of additional collision constellations to the results of respective FEA calculations was carried out. The developed method allows for prediction of injury criteria based on impact constellation for a given vehicle. Because the surrogate models are specific to a certain vehicle, training has to be redone for a new vehicle. Still, there is a large benefit regarding calculation time when doing large-scale studies.

Conclusion: The method can be used in prospective effectiveness assessment studies of new vehicle safety features and takes into account specific local features of a vehicle (geometry, stiffness, etc.) as well as external parameters (location and velocity of pedestrian impact). Furthermore, it can be easily extended to other injury criteria or accident scenarios; for example, cyclist accidents.  相似文献   
107.
Objective: The Lower Anchor and Tethers for CHildren (LATCH) system was introduced in vehicles made after September 1, 2002 and intended to make installation of rear and forward-facing child safety seats easier. Due to the lack of rear impact testing of RFCRS required per the Federal Motor Vehicle Safety Standards (FMVSS), the purpose of this study was to explore the effects, if any, of installation method of RFCRS on the performance of commonly purchased makes and models of RFCRS. Specifically, we hypothesize that in a 48 km/h (29.8 MPH) rear-end collision, installation of RFCRS using the LATCH system will result in higher Head Injury Criteria (HIC) values when compared to using the available lap/shoulder seatbelt (Emergency Locking Retractor - ELR or Automatic Locking Retractor - ALR).

Methods: The test matrix included 36 rear impact sled tests conducted using 3 installation methods on 3 models of RFCRS: the Graco SnugRide® with and without the base, the Britax Chaperone with base-mounted anti-rebound bar, and the Evenflo Tribute®, a model of convertible rearward/forward facing restraint system used in the rearward facing mode. The seats were installed using the LATCH system, ELR lap/shoulder belts, or ALR lap/shoulder belts in seating positions 4 and 6 on a vehicle buck mounted to the sled test base. The infant seat and 6 month old CRABI anthropometric test device (ATD) installation methods were in accordance with standards set forth in the National Highway Traffic Safety Administration's (NHTSA) FMVSS No. 213, Child Restraint Systems. All tests were conducted on pneumatic controlled acceleration sled (HYGE, Inc., PA, USA) at 48 km/h.

Results: Installation of infant seat type RFCRS using the LATCH system resulted in higher HIC15 values when compared to using the available lap/shoulder seatbelt (ELR or ALR). The mean HIC15 values were most severe when infant seat type RFCRS were installed using LATCH (Graco SnugRide® HIC15 = 394 and Britax Chaperone HIC15 = 133) compared to using either ELR lap/shoulder belts (Graco SnugRide® HIC15 = 218 and Britax Chaperone HIC15 = 65) or ALR lap/shoulder belts (Graco SnugRide® HIC15 = 194 and Britax Chaperone HIC15 = 78). The installation method did not result in a statistically significant difference in HIC for the convertible type RFCRS (Evenflo Tribute®). In many of the tests, the ATD's head struck the seatback in which the RFCRS was installed. These head strikes resulted in the higher HIC15 scores recorded throughout the testing.

Conclusions: The results of this study suggest that LATCH does not offer equal protection to lap/shoulder belts from head injuries in rear impacts when used with infant seat type RFCRS.  相似文献   
108.
Due to the characteristic that shape memory materials can quickly return to their original shape and have large deformation, such materials can be used as the connection in active disassembly devices. However, existing active disassembly devices typically require two moulding steps and complicated machining processes that result in high manufacturing cost. The active disassembly device based on the proposed decapitated head method has only one moulding step and lower manufacturing cost. Its disassembly mode is local damage disassembly, which can decrease the active disassembly cost and improve disassembly efficiency. This paper describes the active disassembly theory and the design methodology based on the decapitated head method, and then analyses the design criteria and feasibility of this method with a real case study.  相似文献   
109.
丁义志 《四川环境》2010,29(4):91-94
根据安康中心城市两个饮用水水源地环境现状调查和水质监测结果,按照国家《地表水环境质量标准》(GB3838-2002),采用比照法进行了环境质量现状评价。同时,针对目前水源地存在的环境问题,提出了法律法规和制度保护措施、组织保障措施、各级水源保护区的工程治理措施,以及相应的生态修复与建设重点工程和管理能力建设重点工程等,对于改善水源地生态环境系统,有效地保证安康市生活饮用水质量和促进区域水资源可持续利用具有一定的指导作用。  相似文献   
110.
顶空便携式气相色谱—质谱仪现场测定地表水中苯系物   总被引:2,自引:0,他引:2  
对顶空便携式气相色谱—质谱仪分析水中的苯、甲苯、乙苯、邻-二甲苯、间-二甲苯、对-二甲苯、异丙苯的方法进行了研究,并讨论了平衡时间、平衡温度、水中含盐量等因素对测定的影响。结果表明,方法的回收率为94.15%~98.67%,相对标准偏差为2.32%~4.88%,最低检出限为0.031~0.094μg/L。该方法快速、准确、重复性好。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号