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   1287篇
  免费   95篇
  国内免费   355篇
安全科学   87篇
废物处理   52篇
环保管理   120篇
综合类   767篇
基础理论   294篇
环境理论   1篇
污染及防治   242篇
评价与监测   67篇
社会与环境   76篇
灾害及防治   31篇
  2024年   2篇
  2023年   25篇
  2022年   55篇
  2021年   53篇
  2020年   62篇
  2019年   43篇
  2018年   60篇
  2017年   60篇
  2016年   51篇
  2015年   82篇
  2014年   93篇
  2013年   108篇
  2012年   87篇
  2011年   99篇
  2010年   92篇
  2009年   92篇
  2008年   81篇
  2007年   79篇
  2006年   87篇
  2005年   59篇
  2004年   46篇
  2003年   42篇
  2002年   39篇
  2001年   38篇
  2000年   21篇
  1999年   19篇
  1998年   12篇
  1997年   22篇
  1996年   9篇
  1995年   18篇
  1994年   10篇
  1993年   6篇
  1991年   7篇
  1990年   7篇
  1989年   5篇
  1988年   3篇
  1986年   6篇
  1983年   5篇
  1982年   2篇
  1978年   3篇
  1977年   3篇
  1976年   7篇
  1974年   3篇
  1922年   3篇
  1921年   2篇
  1920年   2篇
  1919年   3篇
  1918年   2篇
  1914年   2篇
  1913年   2篇
排序方式: 共有1737条查询结果,搜索用时 15 毫秒
941.
生态田污水处理技术具有低投资、低能耗、低运行费用等诸多优点,结合油田所处的地理位置及实际生产情况,利用生态田天然植物的生物效能,对油田污水处理后用于植被灌溉,并且针对处理过程中存在的问题提出了工艺改造对策措施,最终实现净化污水的目的。  相似文献   
942.
Dissolved organic matter (DOM) has been shown to affect phytoplankton species directly. These interactions largely depend on the origin and molecular size of DOM and are different in prokaryotes and eukaryotes. In a preceding study, however, two humic substance preparations did not adversely affect coccal green algae or cyanobacterial growth even at high concentrations of dissolved organic carbon (DOC). These results contradicted previous findings, showing a clear, negative response of different phototrophs to much lower DOC concentrations. To test whether or not at least defined building blocks of humic substances (HSs) are effective algicidal structures, we enriched two humic preparations with hydroquinone and p-benzoquinone, respectively, and exposed two different green algae, Pseudokirchneriella subcapitata and Monoraphidium braunii, and two cyanobacterial species, Synechocystis sp. and Microcystis aeruginosa, to the unmodified and enriched HSs. As response variables, growth rates in terms of biomass increase, chlorophyll-a content, and photosynthetic yield were measured. The highest concentration (4.17 mM DOC) of the modified HSs clearly inhibited growth; the cyanobacterial species were much more sensitive than the green algal species. However, realistic ecological concentrations did not adversely affect growth. Aerating the exposure solution for 24 h strongly reduced the inhibitory effect of the modified HSs. The algicidal effect was obviously caused by monomers and not by polymerised high molecular weight HSs themselves. Furthermore, the maximum quantum yield (Φ PSII max) was stimulated in the green algal species by low and medium DOC concentrations, but reduced in the cyanobacterial species upon exposure to higher HS concentrations. The quinone- and phenol-enriched HSs only showed algicidal activity at high concentrations of 4.17 mM DOC and lost their effects over time, presumably by oxidation and subsequent polymerisation. This study confirms that the applied humic substances themselves are not effective algicides even if enriched in effective structures.  相似文献   
943.
金属可能通过生理和生态两方面对微生物的苯酚降解过程产生重要影响.为了提高芽孢杆菌Bacillus sp.JY01(以下称菌株JY01)的苯酚降解效率,探讨了6种金属离子(Ba2+、Cu2+、Co2+、Fe3、Zn2+、pb2+)对其生长和苯酚降解性能的影响.结果表明,在质量分数为0.001%~0.050%时,Cu2+、Zn2+、Co2、Fe3+、Ba2+、pb2+对菌株JY01的生长和苯酚降解均有抑制作用,并且抑制作用总体随金属离子浓度的升高而增强,当6种金属的质量分数分别达到0.005%时,菌株JY01对苯酚的降解能力为Ba2+ <Cu2+ <Co2+ <Fe3+ <Zn2+ <pb2+;金属离子通过影响菌株JY01的生长状况来影响其苯酚降解性能;很多金属离子对菌株JY01生长有明显抑制作用,因此在实际生物处理含苯酚废水时,要考虑废水中金属离子对降解菌生长状况的影响.  相似文献   
944.
将一株产絮酵母菌(编号B-02号)发酵后的废菌体制成生物吸附剂,研究该生物吸附剂对废水中Cd2+的生物吸附特性。结果表明:(1)pH值对Cd2+会产生较大的影响,偏酸性(pH=4~6)条件利于吸附;该吸附剂对Cd2+吸附速率较快,8~10 min就可达到吸附平衡;(2)吸附剂的吸附动力学符合二级动力学模型,吸附Cd2+的实验数据对Langmuir等温式的拟合情况良好,吸附剂吸附Cd2+的最大吸附量为70.752 mg/g。用0.5 mol/L HNO3对吸附Cd2+的酵母菌进行解吸,解吸率可达89.7%。  相似文献   
945.
为提高低挥发分城市污泥水解酸化的效率,采用超声处理与碱性调节组合的手段强化水解酸化过程,探讨组合的方式、条件及其作用效果。通过先进行碱性调节再超声处理与先超声处理再进行碱性调节2种组合方式下的6种组合条件,分析水解酸化过程SCOD、VFAs、氮、磷的变化情况。实验结果表明,2种组合方式的各条件均可促进污泥水解酸化;超声处理后即调pH为9.5的组合条件较其他组合条件更有利于有机质的转化和VFAs的产生,SCOD的转化率达到20.46%,VSS可降低约40%,在5 d水解酸化过程中污泥水解酸化液HAc/VFAs均高于50%,VFAs最高达1 072.51 mg/L;而各组合条件对水解酸化过程中氮磷的释放影响不大。研究指出,超声处理后即进行碱性调节的组合条件能显著强化低挥发分城市污泥的水解酸化效果。  相似文献   
946.
"Working landscapes" is the concept of fostering effective ecosystem stewardship and conservation through active human presence and management and integrating livestock, crop, and timber production with the provision of a broad range of ecosystem services at the landscape scale. Based on a statewide survey of private landowners of "working" forests and rangelands in California, we investigated whether owners who are engaged in commercial livestock or timber production appreciate and manage biodiversity and ecosystem services on their land in different ways than purely residential owners. Both specific uses and management practices, as well as underlying attitudes and motivations toward biodiversity and ecosystem services, were assessed. Correlation analysis showed one bundle of ecosystem goods and services (e.g., livestock, timber, crops, and housing) that is supported by some landowners at the community level. Another closely correlated bundle of biodiversity and ecosystem services includes recreation, hunting/fishing, wildlife habitat, and fire prevention. Producers were more likely to ally with the first bundle and residential owners with the second. The survey further confirmed that cultural ecosystem services and quality-of-life aspects are among the primary amenities that motivate forest and rangeland ownership regardless of ownership type. To live near natural beauty was the most important motive for both landowner groups. Producers were much more active in management for habitat improvement and other environmental goals than residential owners. As the number of production-oriented owners decreases, developing strategies for encouraging environment-positive management by all types of landowners is crucial.  相似文献   
947.
印染废水中含有大量的剩余染料,对生态环境构成了巨大威胁.漆酶能够氧化多种纺织染料使其脱色,在印染废水处理领域具有潜在的应用性.为了开发基于酶技术的印染废水处理工艺,利用商业化的漆酶制剂SUKALaccTM对5种常见纺织染料的脱色能力进行了测试,结果显示,SUKALaccTM对于这些测试的染料均具有脱色效果,脱色效率为14.85%~ 85.97%;此外,还考察了酶制剂浓度、染料浓度、温度和pH等因素对脱色效率的影响,确定了最优的反应条件;利用斜生栅藻(Scenedesmus obliquus)和大型溞(Daphnia magna)分别对酶处理后的染料毒性进行了测试,结果表明,酶制剂处理后的染料毒性减弱.这些实验结果为漆酶制剂实际应用于印染废水处理奠定了坚实基础.  相似文献   
948.
以FeSO4·7H2O为原料,NaClO3氧化法制备出聚合硫酸铁,并用Ti4+与其复合得到复合絮凝剂。运用XRD及FTIR对絮凝剂结构进行了表征,并通过处理油田废水含油量和浊度考察了絮凝剂的絮凝性能。结果表明,Ti4+与聚合硫酸铁复合以后,样品分子量增大,结晶性变差,晶粒变小,无定形结构所占比例增大。Ti4+与聚合硫酸铁不是简单的混合,而是发生了一定的相互作用,并且生成了Ti—O—Fe键。通过正交实验优化出的制备条件为:n(Ti4+)/n(Fe3+)=0.05;合成温度为65℃;搅拌时间为1 h。复合后的产物对油田废水的处理效果优于复合前,且在pH值为7,投加量(以铁计)为20 mg/L时絮凝性能最好,其油去除率与浊度去除率分别为89.8%和98.3%。  相似文献   
949.
曹国民  孙霄  盛梅  沈晓强  金磊 《化工环保》2015,35(6):609-613
针对江苏省某化工园区集中式污水处理厂出水COD和TP高于DB32/939—2006《江苏省化学工业主要水污染物排放标准》规定的排放限值的情况,采用Fenton氧化工艺对该污水处理厂装置进行升级改造。小试最佳工艺条件为:初始污水pH 3.0~3.5,H_2O_2(质量分数30%)加入量0.8 m L/L,FeSO_4·H_2O加入量0.8 g/L,反应时间120min,Fenton氧化反应结束后中和反应的适宜pH约为7.0。升级改造工程包括2套并联运行的处理能力各为10 km~3/d的Fenton氧化系统,装置稳定运行后最终控制H_2O_2加入量为150 L/h,FeSO_4·7H_2O溶液加入量为700 L/h,相应的处理后出水COD和TP分别稳定在60 mg/L和0.4 mg/L以下,可达标排放。每吨污水的处理药剂成本约为0.9元。  相似文献   
950.
Polychlorinated biphenyls (PCBs) and DDT are widespread environmental persistent organic pollutants that have various adverse effects on reproduction, development and endocrine function. In order to elucidate effects of PCBs and DDT on thyroid hormone homeostasis, Sprague–Dawley rats were dosed with PCB153 and p,p′-DDE intraperitoneally (ip) for five consecutive days and sacrificed within 24 h after the last dose. Results indicated that after combined exposure to PCB153 and p,p′-DDE, total thyroxine , free thyroxine, total triiodothyronine, and thyroid-stimulating hormone in serum were decreased, whereas free triiodothyronine and thyrotropin-releasing hormone were not affected. Thyroglobulin and transthyretin levels in serum were significantly reduced. mRNA expression of deiodinases 2 (D2) was also suppressed, while D1 and D3 levels were not significantly influenced after combined exposure. PCB153 and p,p′-DDE induced hepatic enzymes, UDPGTs, CYP1A1, CYP2B1, and CYP3A1 mRNA expressions being significantly elevated. Moreover, TRα1, TRβ1, and TRHr expressions in the hypothalamus displayed increasing trends after combined exposure to PCB153 and p,p′-DDE. Taken together, observed results indicate that PCB153 and p,p′-DDE could disorder thyroid hormone homeostasis via thyroglobulin, deiodinase 2, transthyretin, hepatic enzymes, and hormone receptors.  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