全文获取类型
收费全文 | 1459篇 |
免费 | 59篇 |
国内免费 | 46篇 |
专业分类
安全科学 | 654篇 |
废物处理 | 34篇 |
环保管理 | 115篇 |
综合类 | 313篇 |
基础理论 | 60篇 |
环境理论 | 1篇 |
污染及防治 | 49篇 |
评价与监测 | 31篇 |
社会与环境 | 22篇 |
灾害及防治 | 285篇 |
出版年
2023年 | 29篇 |
2022年 | 18篇 |
2021年 | 58篇 |
2020年 | 49篇 |
2019年 | 42篇 |
2018年 | 32篇 |
2017年 | 24篇 |
2016年 | 29篇 |
2015年 | 66篇 |
2014年 | 53篇 |
2013年 | 81篇 |
2012年 | 119篇 |
2011年 | 113篇 |
2010年 | 83篇 |
2009年 | 99篇 |
2008年 | 46篇 |
2007年 | 90篇 |
2006年 | 85篇 |
2005年 | 85篇 |
2004年 | 56篇 |
2003年 | 44篇 |
2002年 | 34篇 |
2001年 | 24篇 |
2000年 | 22篇 |
1999年 | 24篇 |
1998年 | 31篇 |
1997年 | 14篇 |
1996年 | 17篇 |
1995年 | 23篇 |
1994年 | 17篇 |
1993年 | 14篇 |
1992年 | 10篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有1564条查询结果,搜索用时 15 毫秒
561.
562.
根据构造地质学、地震地质学的考察和观测结果 ,结合构造单元、地震活动分区和研究区位置确定计算模型的范围 ,选定一个构造骨架 ,确定计算模型的边界形状和几何参数。然后参考地震震源机制解结果和新构造运动特征 ,选定模型边界条件 ;参考岩石力学实验结果 ,确定模型的物理参数。最后利用线弹性二维有限元程序计算了各节点位移、各单元应力应变及应变能增量。通过分析应力应变场和应变能增量划分出 2个地震危险区。 相似文献
563.
The polymerization reaction can lower the threshold of the required energy by the initiator to improve the efficiency of the overall process reaction. Emerging polymerization initiators are also a major focus of process improvement and technological progress. Azo compounds (azos), which used in dyeing applications, are subsequently used in polymerization reactions due to their highly exothermic reaction characteristics. Although higher heat release can promote polymerization and modify the product, heat generation may also cause process hazards.These thermal hazard parameters were studied by selecting dimethyl 2,2′-azobis(2,4-dimethylvaleronitrile) (ABVN), 2,2′-azobis(2-methyl propionate) (AIBME), 2,2′-azobis(2-methylpropionamide) dihydrochloride (AIBA), and 2,2′-azobis(isobutyronitrile) (AIBN), which are common azo initiators at present. Thermal hazards are closely related to the reaction kinetics of the substance itself. The form of the reaction, the apparent activation energy and the thermodynamic parameters of the exothermic mode were also obtained.Kinetic analysis of the actual process using the experimental data of the isothermal calorimetry model is rarely used in the evaluation of related thermal hazard characteristics. The simulation results revealed the kinetic azo models and were further applied to calculate the runaway situations of azo under specific boundary conditions. 相似文献
564.
地下水中潜在危害有机物识别与筛选方法 总被引:1,自引:0,他引:1
针对地下水中频繁检出的各类有机物,运用理论方法定量计算污染物对地下水的危害系数,对有机物的污染调查、地下水污染防治具有一定的指导意义。为研究有机物对地下水的危害性,汇总了535项有机物,目前这些指标在国内外水质标准中均没给出标准值。从有机物的自身属性入手,假定所有物质处于相同的外界环境中,经过包气带吸附、降解、挥发等作用,分析其进入地下水的难易程度。利用美国环保局的软件EPI Suit4.10,获取了指标的有机碳吸附系数(Koc)、半衰期(DT50)和亨利常数(KH),并结合毒性参数基于健康的评价基准值,构建了污染物潜在危害参数体系。运用3种方法计算有机物的危害系数H、污染指数G和衰减系数K,对比3种计算结果,筛选出100项潜在危害有机物。分析表明,所筛选出的100项指标毒性较大、难挥发,并且有机物的Koc对污染指数(G)和衰减系数(K)的贡献比DT50、KH更大。 相似文献
565.
566.
J.C. Doornkamp 《Journal of environmental management》1998,52(4):327-333
A review of the difficulties associated with the definition of coastal flood frequencies and magnitudes leads to a recognition that there is considerable doubt in many parts of the world as to the precise nature of this particular hazard. Similarly, a review of the sea-level measurements that have been used to indicate a response to global warming shows that there is uncertainty about the amount of other controlling influences. What is clear, however, are that past management decisions about human endeavours in the coastal zone (including flood defences, occupance of flood-prone lands, extraction of ground water and natural gas) have had an impact on relative land and sea levels and have done more to increase the risk of coastal flooding than can be assigned so far to global warming. In addition, these changes induced by human activity may render inappropriate calculations of coastal-flood frequencies based on historical records since the latter relate to a period of time when the controls on flooding may have been very different. 相似文献
567.
Julius Otutu Oseji 《The Environmentalist》2007,27(2):311-314
Environmental Pollution now persist in Nigeria especially the oil-rich regions of Delta State. One of these problems is due
to gas flaring. Thermal gradient resulting from the gas flared at Kwale/Okpai gas plant is hereby reported. Surface temperature
variations with distance from the flare point were investigated for the four cardinal directions. The results show a surface
temperature elevation of about 3.7° C above the mean normal daily temperature within a radius of 270 M. Hence the thermal
equilibrium has been altered. This increase in temperature has undesirable effect on man and his environment especially on
the socio-economic lives and activities of the inhabitants. It is therefore necessary that Government Agencies empowered to
monitor environment such as Federal Environmental Protection Agency (FEPA) should embark on adequate remediation activities
in order to stop the environmental degradation before enormous and permanent damage is caused. Furthermore, the companies
involved in the gas flaring should be made to be concerned with the danger they may be causing the inhabitants in particular
and the populace in general. 相似文献
568.
The paper discusses the impact of the COVID-19 pandemic on the Italian chemical and process industries, where Directive 2012/18/EU Seveso III, for the control of Major Accident Hazard (MAH), is enforced. The Safety Management System (SMS) for the control of MAH, which has been mandatory for 20 years in Italian Seveso Establishments, has been highly stressed by the external pressure, related in some way to the COVID-19 pandemic. Fairly, most companies, in particular in oil and gas sectors, have demonstrated an adequate capability to reconcile operation continuity and health requirements. This experience is providing the establishment operators and the regulators with valuable suggestions for the improvements of the SMS-MAH. Within this framework, an innovative organisational resilience model is proposed, aiming at the development of a higher capability to face future new crisis. The current SMS-MAH already includes some basic pillars to enhance resilience, which were valuable during the pandemic crisis, but a full and rationale development is still needed. Starting from the first pandemic phase experience, this paper presents a novel tool to assess the degree of “resilience” of a SMS-MAH. It is based on a questionnaire, featuring 25 questions grouped into eight items, according to the typical SMS-MAH structure. A two level AHP model has been developed in order to define the weights to be assigned to each point. The AHP panel included industrial practitioners, regulators, authorities and researchers. The results are based on the COVID-19 experience and consequently the developed model is tailored to face health emergencies, but the approach may be easily transferred to other external crises. 相似文献
569.
Photoperiod and dietary lipids both influence thermal physiology and the pattern of torpor of heterothermic mammals. The aim
of the present study was to test the hypothesis that photoperiod-induced physiological changes are linked to differences in
tissue fatty acid composition of deer mice, Peromyscus maniculatus (∼18-g body mass). Deer mice were acclimated for >8 weeks to one of three photoperiods (LD, light/dark): LD 8:16 (short photoperiod),
LD 12:12 (equinox photoperiod), and LD 16:8 (long photoperiod). Deer mice under short and equinox photoperiods showed a greater
occurrence of torpor than those under long photoperiods (71, 70, and 14%, respectively). The duration of torpor bouts was
longest in deer mice under short photoperiod (9.3 ± 2.6 h), intermediate under equinox photoperiod (5.1 ± 0.3 h), and shortest
under long photoperiod (3.7 ± 0.6 h). Physiological differences in torpor use were associated with significant alterations
of fatty acid composition in ∼50% of the major fatty acids from leg muscle total lipids, whereas white adipose tissue fatty
acid composition showed fewer changes. Our results provide the first evidence that physiological changes due to photoperiod
exposure do result in changes in lipid composition in the muscle tissue of deer mice and suggest that these may play a role
in survival of low body temperature and metabolic rate during torpor, thus, enhancing favourable energy balance over the course
of the winter. 相似文献
570.