全文获取类型
收费全文 | 115篇 |
免费 | 5篇 |
国内免费 | 39篇 |
专业分类
安全科学 | 6篇 |
废物处理 | 3篇 |
环保管理 | 13篇 |
综合类 | 51篇 |
基础理论 | 43篇 |
污染及防治 | 18篇 |
评价与监测 | 5篇 |
社会与环境 | 12篇 |
灾害及防治 | 8篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 8篇 |
2013年 | 2篇 |
2012年 | 6篇 |
2011年 | 4篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 5篇 |
2007年 | 9篇 |
2006年 | 6篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 11篇 |
2001年 | 7篇 |
2000年 | 10篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1987年 | 1篇 |
1986年 | 2篇 |
排序方式: 共有159条查询结果,搜索用时 15 毫秒
81.
干湿交替对福寿螺摄食和生长的影响 总被引:2,自引:0,他引:2
福寿螺(Pomacea canaliculata)被世界自然保护联盟列入世界100种恶性外来入侵物种黑名单,在我国南方已对水稻生产造成严重危害。为了探索通过水分调控来防治福寿螺的方法,本研究模拟福寿螺野外生存条件,探讨不同干湿交替条件下福寿螺摄食和生长的情况,来分析干旱胁迫对其体重增长率(Weight growth rate,WGR)、摄食率(Feeding rate,FR)、食物转化率(Food conversion ratio,FCR)、特定生长率(Specific growth rate,SGR)等的影响。结果表明:福寿螺在干湿交替条件下,其WGR、FR、FCR、SGR均受到明显抑制,甚至出现负值的情况;福寿螺的壳高随着有水时长的延长而增加,出现干旱时间越长,壳高增长越缓慢的现象;福寿螺在短时期干湿交替条件下发生部分补偿生长现象,这种补偿生长效应可能主要是通过饥饿后摄食水平提高而实现的,但超出一定限度时则不能补偿生长。根据上述结果,可以认为福寿螺在缺水条件下无法正常生长,且影响程度随着干旱时间的增加而增大。此外,福寿螺普遍会在旱后复水180min内钻出土壤,因此,可利用此时机防治福寿螺,及时避免其损伤水生作物。本研究结果可为稻田福寿螺的综合防治和水资源利用管理提供理论参考。 相似文献
82.
随着抗虫和耐草甘膦除草剂转基因玉米的迅速推广和种植,其环境安全性也越来越成为人们关注的焦点。为探讨抗虫耐除草剂转基因玉米C0030.3.5(外源基因cry1Ab和epsps)对水生动物环境的安全性,以模式生物大型蚤(Daphnia magna)为指示生物,分别使用1.5 g·L~(-1)C0030.3.5玉米粉和其非转基因对照DBN318玉米粉饲喂大型蚤28 d,探讨C0030.3.5玉米对大型蚤生长和繁殖的影响。结果显示,C0030.3.5玉米粉组大型蚤与亲本DBN318组大型蚤相比,体长、存活率、新生幼蚤总数等没有显著性差异(P0.05)。28 d饲喂实验结果表明,抗虫耐除草剂玉米C0030.3.5没有对大型蚤生长和繁殖产生不良影响。上述研究结果为转基因玉米的商业化种植和安全管理提供科学数据。 相似文献
83.
Centner TJ 《Environmental management》2001,28(5):599-609
Due to concentrations of animals at large facilities, animal feeding operations (AFOs) have emerged as a major potential source
of water pollution. The federal government regulates concentrated animal feeding operations under its point-source pollution
permitting regulations. A major determinant of whether an operation must apply for a permit is the number of animals at an
individual lot or facility. This paper examines federal mandatory controls and voluntary guidelines that seek to reduce contaminant
pollution from AFOs. Land treatment practices are delineated due to their importance in reducing the injurious by-products
of agricultural production. An evaluation of proposed revisions to federal regulations on confined animal feeding operations
suggests they diverge from their goal of controlling water pollution. Federal regulations focus on the size of operation and
amount of manure governed by the permitting process to the exclusion of other criteria related to the impairment of water
quality. Given the uncertainties about the amount of pollution from AFOs, lack of enforcement of existing regulations, localization
of problems, and possible alternatives for addressing the pollution, more demanding federal regulations may not form an appropriate
response. 相似文献
84.
85.
86.
在沿海燃煤电厂,桥式抓斗卸船机振动给料系统频繁出现溜煤、洒煤现象,造成了环境污染并影响了系统的稳定运行。以国华某发电公司的桥式抓斗卸船机振动给料系统为研究对象,通过采用振动给料器自锁系统、升降式导料槽以及优化导料槽通流面积等措施,有效解决了溜煤、洒煤问题。对其它电力、港口、冶金、建材等行业桥式抓斗卸船机振动给料系统优化改造工作具有推广和借鉴意义。 相似文献
87.
According to the current international standards, to perform the correct evaluation of the explosion and flammability parameters, a uniform distribution of the dust particles should be achieved inside the 20 L and/or 1 m3 standard vessels.CFD simulations have shown that in both standard test vessels (20 L and 1 m3), the dust particles are not uniformly dispersed, being mostly concentrated at the edge of the macro-vortices generated by the injection of the fluid and particle through the nozzle. In addition, only a partial fed of the particles is obtained, and dust particles sedimentation phenomena can occur.As a result, the dust participating to the reactive process may be much lower than the expected nominal concentration in the vessel due to sedimentation and incomplete feeding. Consequently, misleading values of the flammability/explosion parameters could be measured.Particle sedimentation and incomplete feeding depends both on the Stokes number and on the Reynolds number, whereas the concentration distribution depends on the turbulence level, the fluid flow maps, and the number of particles which enter into the vessel through the nozzle.The aim of this work is to evaluate the key parameters (particle size, particle density, and fluid velocity) affecting sedimentation and incomplete feeding in 20 L vessel. To this end, CFD simulations of dust dispersion are performed at varying the particle density and size. Operating maps, in terms of the key parameters and/or their dimensionless combinations, are developed and a correlation for correction of the data is proposed. 相似文献
88.
以系统降解效能和产甲烷量最大化为目标,分别考察不同有机负荷(8.93、10.71、13.39 kg·m-3·d-1)及进料频率(1、2、3次·d-1)下厨余垃圾中温厌氧消化系统运行过程中甲烷产量、SCOD、氨氮、pH和挥发性脂肪酸(VFAs)的变化,旨在明确系统负荷边界及进料频率对系统稳定性的影响.结果表明,系统的有机负荷存在最优值,系统累计产甲烷量随负荷的增加而升高,随后降低,有机负荷为10.71 kg·m-3·d-1时获得最大累计产甲烷量37.17 L,VS降解率72.58%.负荷增加系统稳定性下降甚至失稳,各物质出现积累,不利于反应的进行.增加进料频率可优化系统运行参数,显著提高系统产气和产甲烷量,进料频率较高时,运行周期内系统的甲烷产量及产率最高,分别达到45.03 L和0.738 L·g-1,呈线性增长,增加进料频率可提高系统对氨氮的耐受能力,显著提高系统稳定性,明显改善VFA和丙酸积累问题. 相似文献
89.
Annalies Borrel Anna Taylor Marie McGrath rew Seal Elizabeth Hormann Laura Phelps & Frances Mason 《Disasters》2001,25(2):149-163
The preparation and dissemination of policy statements are necessary but insufficient to prevent the inappropriate use of infant-feeding products in emergencies. The widespread failure of humanitarian agencies operating in the Balkan crisis to act in accordance with international policies and recommendations provides a recent example of the failure to translate infant-feeding policies into practice. This article explores the underlying reasons behind the failures which include: (1) the weak institutionalisation of policies; (2) the massive quantities of unsolicited donations of infant-feeding products: (3) the absence of monitoring systems; (4) inadequate co-ordination mechanisms; (5) the high costs of correcting mistakes; and (6) the cumulative effects of poor practice. Efforts to uphold best practice during the crisis are also documented. Finally, the article identifies actions that could be undertaken in advance of and during future emergencies to enhance the application of infant feeding policies in emergencies. 相似文献
90.
城镇污水处理厂低浓度连续进水间歇曝气运行模式分析 总被引:3,自引:0,他引:3
根据南方城镇污水处理厂建成运行初期的实际运行情况,对低浓度进水的运行模式进行了分析和研究。运行中,污水处理厂MISS浓度调整为25g/L,采用曝气3h、停曝5h、连续进水的运行模式,实现了生物系统稳定运行,出水达标。 相似文献