全文获取类型
收费全文 | 686篇 |
免费 | 91篇 |
国内免费 | 407篇 |
专业分类
安全科学 | 138篇 |
废物处理 | 55篇 |
环保管理 | 54篇 |
综合类 | 641篇 |
基础理论 | 107篇 |
污染及防治 | 162篇 |
评价与监测 | 17篇 |
社会与环境 | 4篇 |
灾害及防治 | 6篇 |
出版年
2024年 | 1篇 |
2023年 | 18篇 |
2022年 | 23篇 |
2021年 | 39篇 |
2020年 | 31篇 |
2019年 | 34篇 |
2018年 | 29篇 |
2017年 | 26篇 |
2016年 | 44篇 |
2015年 | 56篇 |
2014年 | 56篇 |
2013年 | 56篇 |
2012年 | 73篇 |
2011年 | 69篇 |
2010年 | 47篇 |
2009年 | 59篇 |
2008年 | 38篇 |
2007年 | 74篇 |
2006年 | 64篇 |
2005年 | 42篇 |
2004年 | 30篇 |
2003年 | 43篇 |
2002年 | 25篇 |
2001年 | 26篇 |
2000年 | 24篇 |
1999年 | 35篇 |
1998年 | 28篇 |
1997年 | 19篇 |
1996年 | 9篇 |
1995年 | 15篇 |
1994年 | 12篇 |
1993年 | 15篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有1184条查询结果,搜索用时 78 毫秒
241.
一个适用于区域性大气环境模拟的大气光化学模式 总被引:10,自引:2,他引:8
根据“计数物种”法对光化学反应机制的分析,建立了一个适用于区域性光化学反应模拟的模式,该模式能较好地模拟出NO_x、O_3及H_2O_2等大气光化学污染物的变化,在保证模拟准确性的同时,该模式形式简单,有利于在实际大气环境质量模拟中应用. 相似文献
242.
243.
Dr. S. C. Yeoh I. L. Sargent C. W. G. Redman B. P. Wordsworth S. L. Thein 《黑龙江环境通报》1991,11(2):117-123
We report the detection of fetal cells in the maternal circulation by enzymatic amplification of a single copy gene sequence that was fetal-specific. Fetal HLA-A2-positive cells were sorted from maternal HLA-A2-negative cells by flow cytometry and confirmed by demonstration of a fetal-specific HLA-DR4 sequence. However, this sequence could not be detected in unenriched maternal DNA prepared at 28 and 32 weeks' gestation. The sensitivity of detection was 1 HLA-DR4-positive cell in 105 HLA-DR4-negative cells. We conclude that prenatal diagnosis of paternally inherited autosomal-dominant genetic defects may be possible by selective gene amplification of maternal peripheral blood. However, preliminary enrichment for fetal cells may be necessary. 相似文献
244.
TheeffectoflightontheMn(II)orFetlll)xatalyzedoxidationofaqueousS(IV)XuYongfu(InstituteofAtmosphericPhysics,ChineseAcademyofSc... 相似文献
245.
Jiaen Liu Dr Willy Lissens Paul Devroey Andre Van Steirteghem Ingeborg Liebaers 《黑龙江环境通报》1993,13(9):873-880
The efficiency of the polymerase chain reaction (PCR) in detecting the cystic fibrosis (CF) ΔF508 mutation (which is the most common mutation of CF) was assessed in single human blastomeres. Twenty-one human immature oocytes (germinal-vesicle-stage oocytes) that had been donated for research were matured in vitro and a single spermatozoon from a carrier of the CF ΔF508 mutation was injected into the ooplasm. Fourteen embryos were obtained after intracytoplasmic sperm injection (ICSI). PCR analysis was carried out on 70 single blastomeres isolated from these 14 embryos. The results showed that the efficiency of DNA amplification by PCR in single nucleate blastomeres was 94 per cent (59/63). There were no false-positive results since none of the blank samples or the blastomeres without a nucleus showed an amplified signal. We found that nine embryos were homozygous for the unaffected genotype and that four embryos were heterozygous since they contained both the unaffected and the ΔF508 genotype. In a four-cell embryo, we observed the homozygous unaffected genotype in one blastomere and a heterozygous ΔF508/unaffected genotype in the other three blastomeres. 相似文献
246.
Calculation method of quantum efficiency to TiO2 nanocrystal photocatalysis reaction 总被引:2,自引:0,他引:2
The quantum yield is an important factor to evaluate the efficiency of photoreactor.This article vires an overall calculation method of the quantum efficiency(Φ) and the apparent quantum efficiency(Φa) to the TiO2/UV photocatalysis system.Furthermore,for the immobility system(IS),the formulation of the faction of light absorbed by the TiO2 thin film is proposed so as to calculate the quantum efficiency by using the measured value and theoretic calculated value of transmissivity(T).For the suspension system(SS),due to the difficulty to obtain the adsorption coefficient(α) of TiO2 particulates,the quantum efficiency is calculated by means of the relative photonic efficiency(ζr)and the standard quantum yield(Φstandard). 相似文献
247.
Pi Yunzheng Wang Jianlong 《Frontiers of Environmental Science & Engineering in China》2007,1(2):179-183
The reaction mechanism and pathway of the ozonation of 2,4,6-trichlorophenol (2,4,6-TCP) in aqueous solution were investigated.
The removal efficiency and the variation of H2O2, Cl− formic acid, and oxalic acid were studied during the semi-batch ozonation experiments (continuous for ozone gas supply, fixed
volume of water sample). The results showed that when there was no scavenger, the removal efficiency of 0.1 mmol/L 2,4,6-TCP
could reach 99% within 6 min by adding 24 mg/L ozone. The reaction of molecular ozone with 2,4,6-TCP resulted in the formation
of H2O2. The maximal concentration of H2O2 detected during the ozonation could reach 22.5% of the original concentration of 2,4,6-TCP. The reaction of ozone with H2O2 resulted in the generation of a lot of OH• radicals. Therefore, 2,4,6-TCP was degraded to formic acid and oxalic acid by
ozone and OH• radicals together. With the inhibition of OH• radicals, ozone molecule firstly degraded 2,4,6-TCP to form chlorinated
quinone, which was subsequently oxidized to formic acid and oxalic acid. Two reaction pathways of the degradation of 2,4,6-TCP
by ozone and O3/OH• were proposed in this study.
Translated from Acta Scientiae Circumstantiae, 2005, 25(12): 1619–1623 [译自: 环境科学学报] 相似文献
248.
姜杰 《安全.健康和环境》2020,(3):38-41
采用参数敏感性分析方法对聚丙烯装置环管反应器反应温度、转化率对初温的安全敏感性进行了研究。结果表明,反应初温在72~74℃的范围属于反应器的温度敏感区域,超过74℃则进入温度极敏感区域,可引起反应器堵塞、出料泵过载,严重时可造成非正常停车、甚至超压爆炸事故。 相似文献
249.
三氯乙烯和四氯乙烯与羟基自由基加成反应的理论研究 总被引:2,自引:0,他引:2
用从头计算法在UHF/6-31G水平上研究了三氯乙烯和四氯乙烯与羟基自由基的加成反应,通过振动分析确认了过渡态,计算了内禀反应坐标(IRC)。研究表明,该反应能生成较稳定的加成中间体,活化势垒分别为50.87kJ·mol^-1和63.83kJ·mol^-1,且二者反应在常温下均为熵减、放热、吉布斯自由能变化小于零,能自发进行的过程。 相似文献
250.
王君 《辽宁城乡环境科技》2006,26(1):48-49
文中介绍了用固体废弃物焚烧炉处理城市生活垃圾时的燃烧过程和燃烧机理。在介绍垃圾三成分(水分、可燃分、碳)与低位驻热量之间的关系的基础上,分析了燃烧中所需的理论空气量、实际空气量、空气比,同时介绍了具体计算公式。 相似文献