全文获取类型
收费全文 | 2451篇 |
免费 | 177篇 |
国内免费 | 437篇 |
专业分类
安全科学 | 611篇 |
废物处理 | 40篇 |
环保管理 | 201篇 |
综合类 | 1480篇 |
基础理论 | 381篇 |
污染及防治 | 133篇 |
评价与监测 | 35篇 |
社会与环境 | 47篇 |
灾害及防治 | 137篇 |
出版年
2024年 | 30篇 |
2023年 | 70篇 |
2022年 | 77篇 |
2021年 | 96篇 |
2020年 | 55篇 |
2019年 | 89篇 |
2018年 | 58篇 |
2017年 | 71篇 |
2016年 | 52篇 |
2015年 | 94篇 |
2014年 | 269篇 |
2013年 | 97篇 |
2012年 | 123篇 |
2011年 | 123篇 |
2010年 | 106篇 |
2009年 | 90篇 |
2008年 | 244篇 |
2007年 | 247篇 |
2006年 | 225篇 |
2005年 | 150篇 |
2004年 | 142篇 |
2003年 | 75篇 |
2002年 | 88篇 |
2001年 | 83篇 |
2000年 | 54篇 |
1999年 | 41篇 |
1998年 | 25篇 |
1997年 | 38篇 |
1996年 | 28篇 |
1995年 | 41篇 |
1994年 | 24篇 |
1993年 | 21篇 |
1992年 | 9篇 |
1991年 | 11篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
排序方式: 共有3065条查询结果,搜索用时 0 毫秒
271.
272.
273.
Process of rice straw degradation and dynamic trend of pH by the microbial community MC1 总被引:6,自引:1,他引:6
LIU Jian-bin WANG Wei-dong YANG Hong-yan WANG Xiao-fen GAO Li-juan CUI Zong-jun 《环境科学学报(英文版)》2006,18(6):1142-1146
The process of the rice straw degradation in the fermentor with aeration at 290 ml/h was studied. The results of dissolved oxygen (DO) indicated that the optimum DO during cellulose degradation by microbial community MC1 ranged from 0.01 to 0.12 mg/L. The change model ofpH values was as follows: irrespective of the initial pH of the medium, pH values decreased rapidly to approximate 6.0 after being inoculated within 48 h when cellulose was strongly degraded, and then increased slowly to 8.0--9.0 until cellulose was degraded completely. During the degradation process, 15 kinds of organic compounds were checked out by GC-MS. Most of them were organic acids. Quantity analysis was carried out, and the maximum content compound was ethyl acetate which reached 13.56 g/L on the day 4. The cellulose degradation quantity and ratio analyses showed that less quantity (under batch fermentation conditions) and longer interval (under semi-fermentation conditions) of rice straw added to fermentation system were contributed to matching the change model of pH, and increasing the quantity and ratio of rice straw degradation during cellulose degrading process. The highest degradation ratio was observed under the condition office straw added one time every five days (under semi-fermentation conditions). 相似文献
274.
275.
276.
Decomposition experiments conducted with and without microbial processes are commonly used to study the effects of environmental microorganisms on the degradation of organic pollutants.However,the effects of biological pretreatment (sterilization) on organic matter often have a negative impact on such experiments.Based on the principle of water total organic carbon (TOC) analysis,the effects of physical sterilization treatments on determination of TOC and other water quality parameters were investigated.The results revealed that two conventional physical sterilization treatments,autoclaving and 60 Co γ-radiation sterilization,led to the direct decomposition of some organic pollutants,resulting in remarkable errors in the analysis of TOC in water samples.Furthermore,the extent of the errors varied with the intensity and the duration of sterilization treatments.Accordingly,a novel sterilization method for water samples,0.45 μm micro-filtration coupled with ultraviolet radiation (MCUR),was developed in the present study.The results indicated that the MCUR method was capable of exerting a high bactericidal effect on the water sample while significantly decreasing the negative impact on the analysis of TOC and other water quality parameters.Before and after sterilization treatments,the relative errors of TOC determination could be controlled to lower than 3% for water samples with different categories and concentrations of organic pollutants by using MCUR. 相似文献
277.
采用Pd/Fe双金属对2,4-二氯苯氧乙酸(2,4-D)进行催化还原脱氯,以活性污泥对2,4-D脱氯产物进行生物氧化,考察初始pH、活性污泥量、污染物初始浓度、温度等因素对生物氧化的影响情况.通过PCR-变性梯度凝胶电泳分析污泥体系菌群变化情况,高效液相色谱测定来推测目标污染物的降解过程.结果表明:1 Pd/Fe双金属可有效还原2,4-D,其主要先还原为2-氯苯氧乙酸(2-CPA),最终顺序脱氯为苯氧乙酸(PA).2 2,4-D具有较大生物毒性,其脱氯产物毒性下降,更易被生物降解.3 pH=7、污泥量50 mL/200 mL、适量的初始PA浓度(14.6 mg·L-1)和30℃均有利于PA的去除.在该条件下反应96 h,PA去除率可达84.3%. 相似文献
278.
环境应急监测工作现状存在的问题及对策研究 总被引:5,自引:0,他引:5
近年来,各类突发性环境污染事故时有发生,造成生命、财产的巨大损失和生态系统的严重破坏,这一问题引起了世界各国的高度重视.由于突发性污染事故具有爆发的突然性.危害的严重性以及影响的广泛性和长期性等特点,采取切实有效的措施来预防这类事故的发生以及提高对事故处理处置应变能力,已经成为环境保护一项非常重要的工作,因此建立健全有效的环境应急监测系统,加强各级环境监测站应急监测能力建设,提高其应急监测能力,意义十分重大.环境应急监测对于防范突发性环境污染事故,在事前预防、事中监测、事后恢复的各个过程中起着极其重要的作用,环境应急监测已成为环境监测的重要组成部分.本文系统地分析了我国环境应急监测工作现状,针对实际工作中存在的问题,提出了解决对策. 相似文献
279.
280.
在距离地球表面15—50公里的高空平流层,有一层包围在地球外围空间的臭氧层。由于具有吸收太阳辐射的绝大部分有害紫外线的功能,臭氧层对保护人体和其他生物免遭有致癌和杀伤作用的短波辐射的照射起到举足轻重的作用,并因此被亲切地称为“地球的保护伞”。 相似文献