首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   249篇
  免费   1篇
  国内免费   10篇
安全科学   13篇
废物处理   45篇
环保管理   11篇
综合类   40篇
基础理论   33篇
污染及防治   93篇
评价与监测   8篇
社会与环境   16篇
灾害及防治   1篇
  2023年   2篇
  2022年   5篇
  2021年   5篇
  2020年   1篇
  2019年   3篇
  2018年   6篇
  2017年   5篇
  2016年   8篇
  2015年   5篇
  2014年   3篇
  2013年   19篇
  2012年   10篇
  2011年   15篇
  2010年   17篇
  2009年   18篇
  2008年   21篇
  2007年   23篇
  2006年   13篇
  2005年   9篇
  2004年   19篇
  2003年   6篇
  2002年   14篇
  2001年   5篇
  2000年   5篇
  1999年   3篇
  1998年   1篇
  1997年   3篇
  1996年   1篇
  1994年   2篇
  1992年   3篇
  1989年   1篇
  1984年   1篇
  1982年   1篇
  1979年   2篇
  1977年   2篇
  1969年   1篇
  1957年   1篇
  1956年   1篇
排序方式: 共有260条查询结果,搜索用时 65 毫秒
81.
Generation of reactive oxygen intermediates (ROI) such as O(2)(-), H(2)O(2), and *OH is known to be a major mechanism of damage in biological systems. This study investigated and compared effectiveness of scavenging ROI generated in fluoranthene (FLU) pre-fumigated Japanese red pine seedlings. Three kinds of eco-physiological assessments were used to express the impact of the different fumigants used inside the green house. Gas exchange measurements showed negative changes induced by 10 microM FLU on Japanese pine seedlings during a 10 d exposure period whilst no negative change was found during a 5 d exposure period. Moreover, during a 14 d FLU exposure incorporating ROI scavengers, results revealed that chlorophyll fluorescence, needle chemical contents and needle dry mass per unit area of the seedlings were affected. The negative effects of FLU on the conifer were dependent on both the dose and period of FLU fumigation. Peroxidase (PERO), superoxide dismutase (SOD) and mannitol (MANN) were all effective scavengers of ROI. MANN scavenged *OH, the most lethal of the ROI. For practicable use, MANN is more economical, and may be the best ROI scavenger among the three considered. It can be concluded that efficient scavenging of ROI in biological systems is important to mitigate the negative effects of FLU on Japanese red pine trees.  相似文献   
82.
We intended to find thermophilic degraders of terephthalate-containing Biomax® films. Films in mesh bags were buried in composts (inside temperature: approximately 55–60 °C), resulting in the degradation of them in 2 weeks. Fluorescent microscopy of films recovered from composts showed that microorganisms gradually covered the surface of a film during composting. DGGE analysis of microorganisms on the composted film indicated the presence of Bacillus species as main species (approximately 80% of microbial flora) and actinomycetes (approximately 10–20%) as the second major flora. Isolation of Biomax®-utilizing bacteria was focused on these two genera: two actinomycetes and one Bacillus species were isolated as pure best degraders from the composted polymer films, which were fragmented into small pieces. All the strains were thermophilic and identified, based on their 16S rDNA analyses. Degradation of polymer films was confirmed by (1) accelerated fragmentation of films in composts, compared with a control (no inoculum) and resultant decrease in molecular weights, (2) growth in a powdered Biomax® medium, compared with a control without powdered Biomax®, and (3) production of terephthalate in a powdered Biomax® medium. In this way, we concluded that these bacteria were useful for degradation of thermostable Biomax® products.  相似文献   
83.
The present research was intended to determine the suitability of the CALUX assay as a screening method for dioxins in fish oil used as a feed ingredient in Japan. Alteration of TEQ in fish oil according to newly proposed toxic equivalency factors (TEF) is also discussed. In the analysis, polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in 41 fish oil samples were determined by using high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS) and CALUX bioassay. The mean TEQ values derived from 1998 WHO-TEF of PCDD/Fs and DL-PCBs were 2.6 and 9.9 pg g(-1) (ww), respectively. The levels of TEQ derived from the recently re-evaluated 2005 WHO-TEF were slightly lower than those of the former in both groups. Notably, the contribution of mono-ortho DL-PCBs to total 2005 WHO-TEQ was considerably decreased compared to the case of 1998 WHO-TEQ, resulting from the reduction in its TEF values, while the non-ortho DL-PCBs contribution was increased. The mean TEQ determined by CALUX assay for PCDD/Fs was approximately three times higher, whereas DL-PCBs was approximately two times lower than WHO-TEQ determined by HRGC/HRMS; the sum of PCDD/Fs and DL-PCBs was very similar by both methods. The correlation coefficients of TEQ between the CALUX assay and HRGC/HRMS analysis were 0.84, 0.89, and 0.90 for PCDD/Fs, DL-PCBs, and the sum, respectively. These results suggest that the CALUX assay is a very useful method for the screening of dioxin-related compounds in fish oils.  相似文献   
84.
Jonsson CM  Aoyama H 《Chemosphere》2007,69(6):849-855
Acid phosphatase plays important roles in algae metabolism such as availability and recycling of inorganic phosphate, autophagic digestive processes and fertilization. Chemicals released into the environment from agriculture activities may impair algae phosphatase activity. The aim of this work was to evaluate the in vitro effect of twenty-four organic compounds and six metals used as pesticides, or present as contaminants in sewage sludge, on the acid phosphatase activity extracted from Pseudokirchneriella subcapitata. Results demonstrated that only the linear surfactant alkyl benzenesulphonate (LAS) and the heavy metals Hg(2+), Al(3+) and Cu(2+) markedly altered (50%) the enzyme activity. Join action inhibition studies indicated that Hg(2+) was more potent inhibitor than Al(3+) or LAS, and that the Hg(2+)+Al(3+) and Hg(2+)+LAS mixtures have, respectively, additive and slight antagonism effects. Copper, which demonstrated an activator effect when preincubated with the enzyme, behaved as a slight antagonist for the inhibitor effect of Hg(2+).  相似文献   
85.
Syntheses of some metabolites of ubiquinone and of related compounds are described. Idebenone (QSA-10), a methyl-dimethoxy-benzoquinone bearing an omega-hydroxydecyl side chain in 3-position, restored the oxidation of succinate and of NADH in ubiquinone-depleted mitochondrial preparations and showed a stabilizing effect on lysosomal membranes and an inhibitory effect on cAMP-phosphodiesterase. It inhibited lipid peroxidation in canine brain mitochondria and in microsomes from canine brain and rat liver. Administered orally to rats, it increased the respiratory control index for glutamate and succinate oxidation but had no effect on the ADP/O2 ratio. Pharmacological effects of idebenon are also briefly discussed.  相似文献   
86.
87.
Authors review the importance of studying the effects of electromagnetic fields (EMF) on microcirculatory system, especially in respect of possibility that vasculature may have direct and indirect role in interaction of static magnetic fields (SMF). We outline the physiological importance of microcirculation and relatively new methods of evaluation technique in vivo and explain in details the local and/or whole body exposure effects of SMF with␣range of 0.3–180 mT, power frequency EMF with range of 0.1–30 mT and microwaves at 1.5 GHz with range 0.08–8 W/kg brain average specific absorption rate (SAR) on microcirculatory systems in different tissues in experimental animals.  相似文献   
88.
Gielen D  Yagita H 《Ambio》2002,31(1):14-20
The NEAT model (Nonenergy-use Emission Accounting Tables) has been developed in order to estimate CO2 emissions caused by so-called nonenergy use of fossil fuels. The model is based on material flow accounting. The model has been applied to a number of countries in order to validate and improve its use. This paper discusses the case study for Japan. The NEAT analysis suggests that emissions in 1996 were 23 Mt higher than previously estimated based on the guidelines of the Intergovernmental Panel on Climate Change (IPCC). This quantity equals 1.9% of the total Japanese greenhouse gas emission. It is recommended to adjust the Japanese emission accounting practice and to apply more detailed emission estimation methods in future years. Given similar results for other countries it is also recommended to improve the IPCC guidelines.  相似文献   
89.
Investing in safety an analytical precautionary principle   总被引:6,自引:0,他引:6  
PROBLEM: Governments and businesses must respond to increasing safety requirements and balance the associated costs with productivity and competing pressures. METHOD: A real options approach has been introduced for decision making in the private sector; this approach is adapted for regulatory decisions that can involve irreversible and uncertain safety impacts, social costs that differ from private costs, and differences in perception among the stakeholders. RESULT AND IMPACT ON INDUSTRY AND GOVERNMENT: The outcome is an economic decision gage that determines if it is optimal to invest in safety even if the estimated costs significantly exceed the estimated benefits. Applications potentially include safety decisions related to aviation, ground transportation, pipelines, nuclear facilities, natural disaster planning, and terrorism, among others.  相似文献   
90.
壬基酚聚氧乙烯醚在MBR 与CASR 中的行为   总被引:1,自引:0,他引:1       下载免费PDF全文
对比研究了壬基酚聚氧乙烯醚(NPnEO, n 为1~4)在膜-生物反应器(MBR)和传统活性污泥反应器(CASR)中的去除效果和迁移行为.结果表明,在相同NPnEO 污泥负荷的条件下,采用不主动排泥的运行模式,2 种反应器均能有效去除NPnEO,去除率分别为99.2%和97.1%,MBR 的去除效果更稳定.前21d 中,2 种反应器中混合液NPnEO 浓度均呈现先增大后减小的趋势,但MBR 出水NPnEO 浓度小于其混合液浓度,而CASR 出水浓度则高于其混合液浓度;21d 后,2 种反应器混合液与出水浓度均趋于一致.活性污泥对NPnEO 具有吸附作用,但对去除NPnEO 的贡献很小;推测生物降解是去除NPnEO 的主导作用.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号