全文获取类型
收费全文 | 25502篇 |
免费 | 2214篇 |
国内免费 | 5281篇 |
专业分类
安全科学 | 2969篇 |
废物处理 | 375篇 |
环保管理 | 4039篇 |
综合类 | 16132篇 |
基础理论 | 2817篇 |
环境理论 | 16篇 |
污染及防治 | 1708篇 |
评价与监测 | 2006篇 |
社会与环境 | 1827篇 |
灾害及防治 | 1108篇 |
出版年
2024年 | 77篇 |
2023年 | 445篇 |
2022年 | 756篇 |
2021年 | 952篇 |
2020年 | 964篇 |
2019年 | 816篇 |
2018年 | 710篇 |
2017年 | 904篇 |
2016年 | 1028篇 |
2015年 | 1188篇 |
2014年 | 1266篇 |
2013年 | 1573篇 |
2012年 | 1774篇 |
2011年 | 1977篇 |
2010年 | 1476篇 |
2009年 | 1457篇 |
2008年 | 1194篇 |
2007年 | 1759篇 |
2006年 | 1756篇 |
2005年 | 1373篇 |
2004年 | 1171篇 |
2003年 | 1303篇 |
2002年 | 1090篇 |
2001年 | 945篇 |
2000年 | 856篇 |
1999年 | 755篇 |
1998年 | 578篇 |
1997年 | 484篇 |
1996年 | 407篇 |
1995年 | 349篇 |
1994年 | 342篇 |
1993年 | 269篇 |
1992年 | 219篇 |
1991年 | 170篇 |
1990年 | 119篇 |
1989年 | 63篇 |
1988年 | 56篇 |
1987年 | 50篇 |
1986年 | 36篇 |
1985年 | 38篇 |
1984年 | 20篇 |
1983年 | 20篇 |
1982年 | 29篇 |
1981年 | 29篇 |
1980年 | 22篇 |
1979年 | 21篇 |
1978年 | 20篇 |
1977年 | 18篇 |
1973年 | 16篇 |
1971年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Large TNT equivalent explosions usually arise from accidents occurring during the transportation, storage, and manufacturing of chemicals relevant to process industries. The blast wave generated by the explosion will spread and interact with the surrounding factories and storehouses, damaging the building structures within several kilometers and causing significant casualties and property losses. This study aims to develop an efficient numerical simulation method to predict blast loads to estimate the consequences of accidents involving far-field free air bursts or surface burst explosions. Before its interaction with the interested target, a blast wave is generated in the numerical model by specifying the initial and boundary conditions of the disturbed air. Based on empirical data of incident overpressure, an explicit formula to calculate the air particle velocity is derived from the governing equations of a perfect inviscid gas. A simplified path line method is proposed to calculate the air density. The proposed method is applied to the LS-DYNA CESE solver to simulate the blast loads on building structures in the far field. Validations against empirical data and experiments indicate that the proposed method is sufficiently accurate for engineering applications and, through a case study, presents a more efficient performance than the LOAD_BLAST_ENHANCED (LBE) and mapping methods. 相似文献
2.
2016—2017年武汉市城区大气PM2.5污染特征及来源解析 总被引:1,自引:0,他引:1
利用2016年1月至2017年9月湖北省环境监测中心站大气复合污染自动监测站的在线监测数据,对武汉市城区PM2.5的污染特征及主要来源进行解析。结果表明,武汉市城区PM2.5质量浓度呈现出明显的季节差异,季节变化规律为冬季>春季>秋季>夏季。水溶性离子的主要成分SO42-、NO3-和NH4+占总离子质量浓度的82.0%。PM2.5中阴离子相对阳离子较为亏损,颗粒整体呈碱性。夏季气态污染物的氧化程度较高且SO2较NO2氧化程度高。后向轨迹分析结果表明,区域传输是武汉市PM2.5的一个重要来源,在4个典型重污染阶段,武汉市分别受到局地、东北、西北及西南方向气团传输的影响。PMF模型解析出武汉市PM2.5五大主要来源及平均贡献率:扬尘22.0%、机动车排放27.7%、二次气溶胶21.6%、重油燃烧14.9%和生物质燃烧13.8%。 相似文献
3.
汞污染具有生物积累性,因而得到社会广泛关注。研究监测和评估了郑州市城区土壤和绿色植物叶片中汞浓度、分布、污染水平等。研究发现郑州市主城区土壤总汞浓度为0. 150~0. 958 mg/kg,平均浓度为0. 448 mg/kg;郑州市主城区绿色植物叶片总汞浓度为0. 017~0. 249 mg/kg,平均浓度为0. 107 mg/kg;土壤和叶片中汞浓度按功能区排序为交通枢纽区工业区商业区行政区高教区住宅区。采用地累积指数法对郑州市80个土壤样品的汞污染水平进行评估,结果显示60%受到轻度污染,35%受到偏中度污染,5%受到中度污染。研究较为全面地分析了土壤汞污染的现状及浓度,为郑州市土壤汞污染防治提供参考。 相似文献
4.
为了解石家庄市2016年春季大气颗粒物的铅污染特征及来源,利用单颗粒气溶胶质谱仪(SPAMS),分析了大气中含铅颗粒的化学成分。结果表明: 研究期间大气环境中含铅颗粒数浓度共出现11次跳跃式升高,跳跃时间段内石家庄均处于轻度污染过程。从成分分析来看,含铅颗粒分为纯铅颗粒、Pb与K(Pb-K)、OC(Pb-OC)、Cl(Pb-Cl)、混合颗粒等八大类。观测结果表明:Pb-K颗粒最多,占到含铅颗粒的84.4%;其次为纯铅颗粒,占比为13.0%。与石家庄市污染源谱库比对进行来源解析,得到Pb-K颗粒主要来自生活垃圾焚烧源, 纯铅颗粒主要来自工业源。结合石家庄市大气污染源排放清单和后向气流轨迹分析,推测含铅颗粒可能来自市区西南方向某区县的生活垃圾焚烧企业。 相似文献
5.
Samal Kaumbekova Mehdi Amouei Torkmahalleh Naoya Sakaguchi Masakazu Umezawa Dhawal Shah 《Frontiers of Environmental Science & Engineering》2023,17(2):15
6.
Waste accumulation is a grave concern and becoming a transboundary challenge for environment. During Covid-19 pandemic, diverse type of waste were collected due to different practices employed in order to fight back the transmission rate of the virus. Covid-19 was proved to be capricious catastrophe of this 20th century and even not completely eradicated from the world. The havoc created by this imperceptible quick witted, pleomorphic deadly virus can't be ignored. Though a number of vaccines have been developed by the scientists but there is a fear of getting this virus again in our life. Medical studies prove that immunity drinks will help to reduce its reoccurrences. Coconut water is widely used among all drinks available globally. Its massive consumption created an incalculable pile of green coconut shells around the different corners of the world. This practice generating enormous problem of space acquisition for the environment. Both the environment and public health will benefit from an evaluation of quantity of coconut waste that is being thrown and its potential to generate value added products. With this context, present article has been planned to study different aspects like, coconut waste generation, its biological properties and environmental hazards associated with its accumulation. Additionally, this review illustrates, green technologies for production of different value added products from coconut waste. 相似文献
7.
Pankaj Kumar Vandana Mishra Saiyami Bhardwaj Shafali Garg Ludovic F. Dumée Radhey Shyam Sharma 《环境质量管理》2023,32(4):9-17
Sectorial approach for monitoring heavy metal pollution in rivers has failed to report realistic pollution status and associated ecological and human health risks. The increasing spread of heavy metals from different sources and emerging risks to human and environmental health call for reexamining heavy metal pollution monitoring frameworks. Also, the sources, spread, and load of heavy metals in the environment have changed significantly over time, requiring consequent modification in the monitoring frameworks. Therefore, studies on heavy metal monitoring in rivers conducted in the last decade were evaluated for experimental designs, research frameworks, and data presentations. Most studies (∼99%) (i) lacked inclusiveness of all environmental compartments; (ii) focused on “one pollutant – one/two compartment” or sometimes “one pollutant – one compartment – one effect” approach; and (iii) remained “data-rich but information poor.” An ecological approach with integrative system thinking is proposed to develop a holistic approach for monitoring river pollution. It is visualized that heavy metal monitoring, risk analyses, and water management must incorporate tracking pollutants in different environmental compartments of a river (water, sediment, and floodplain/bank soil) and consider correlating it with riverbank land use. The systems-based pollution monitoring and assessment studies will reveal the critical factors that drive heavy metals pollutant movement in ecosystems and associated potential risks to the environment, wildlife, and humans. Also, water quality and pollution indexing tools would help better communicate complex pollution data and associated risks among all stakeholders. Therefore, integrating systems approaches in scientific- and policy-based tools would help sustainably manage the health of rivers, wildlife, and humans. 相似文献
8.
分析了我国居住建筑室内PM_(2.5)污染水平,总结了现阶段PM_(2.5)的研究方法,主要包括理论分析法、数值模拟法和实验测试法。指出室外源是室内PM_(2.5)的主要污染来源,而室内烟草烟雾、烹饪及人员活动也会严重影响室内PM_(2.5)浓度。针对目前研究中存在的问题,提出了标定典型建筑在不同影响因素下的I/O比范围、研究家具和家电的颗粒物释放状况、加强农村室内外空气颗粒物污染调查等建议。 相似文献
9.
Elise Remling 《环境政策》2018,27(3):477-497
The ways in which climate adaptation is understood in the European Union is examined via three key policy documents: the Strategy on adaptation and the Green and White Papers that preceded it. Drawing on Poststructuralist Discourse Theory, light is shed on the implicit values and assumptions that underpin this recent policy initiative. The findings demonstrate a tension between the declared ambition to act on adaptation and implicit suggestions that nothing really has to change, and the challenge can be addressed by market and technological innovations, and by mainstreaming adaptation into existing sectoral policies. The policy discourse effectively serves to depoliticize choices societies make in response to climate change, presenting adaptation as a non-political issue. Insight into European adaptation discourse enables deeper understanding of recent policy developments and opens up possible entry points for critique. 相似文献
10.
固定源排污许可证监测管理制度研究 总被引:5,自引:2,他引:3
依靠排污许可证管理,固定源执行由行业排放标准为主正逐步过渡到"国家行业排放标准——单一源排放标准"双层排放标准,并以执行更全面和精准的单一源排放标准为主,对应的监测要求及考核方式更加多样化。对监测管理制度进行设计,明确固定源制定自行监测方案和守法监测的主体责任,厘清许可证核发部门、属地监测、执法部门的监管职责。系统设计"固定源制定并提交自行监测方案-核发部门审核-方案纳入排污许可证中成为规定-依规定自行监测和记录-固定源提交执行报告-监管部门审计式审核-执法监测和执法检查"的全过程管理机制,设计标准化的监管计划程序落实证后监管与执法监测,明晰监管部门的有限责任。 相似文献