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   246篇
  免费   80篇
  国内免费   103篇
安全科学   19篇
废物处理   49篇
环保管理   35篇
综合类   173篇
基础理论   88篇
污染及防治   43篇
评价与监测   4篇
社会与环境   10篇
灾害及防治   8篇
  2024年   1篇
  2023年   7篇
  2022年   10篇
  2021年   7篇
  2020年   9篇
  2019年   8篇
  2018年   62篇
  2017年   6篇
  2016年   15篇
  2015年   10篇
  2014年   11篇
  2013年   21篇
  2012年   26篇
  2011年   28篇
  2010年   13篇
  2009年   14篇
  2008年   9篇
  2007年   19篇
  2006年   25篇
  2005年   18篇
  2004年   12篇
  2003年   14篇
  2002年   9篇
  2001年   10篇
  2000年   11篇
  1999年   12篇
  1998年   5篇
  1997年   7篇
  1996年   6篇
  1995年   5篇
  1994年   7篇
  1993年   5篇
  1992年   4篇
  1990年   2篇
  1981年   1篇
排序方式: 共有429条查询结果,搜索用时 31 毫秒
41.
A review of the chemical ecology of the Cerambycidae (Coleoptera)   总被引:15,自引:0,他引:15  
Summary. This review summarizes the literature related to the chemical ecology of the Cerambycidae and provides a brief overview of cerambycid biology, ecology, economic significance, and management. Beetles in the family Cerambycidae have assumed increasing prominence as pests of forest and shade trees, shrubs, and raw wood products, and as vectors of tree diseases. Exotic species associated with solid wood packing materials have been notable tree killers in North American urban and peri-urban forests. In forested ecosystems native species respond to disturbances such as fires and windstorms, and initiate the biodeterioration of woody tissue. Eggs are laid by females, on or through the bark surface of stem and branch tissue of moribund, recently killed or decomposing woody plants; larval cerambycids (roundheaded woodborers) typically feed in the phloem and later in the xylem. Females will also, in some cases, select living hosts, e.g. adult conifer and angiosperm trees, for oviposition. Research on the chemical ecology of over 70 species has revealed many examples of attractive kairomones (such as floral volatiles, smoke volatiles, trunk and leaf volatiles, and bark beetle pheromones), repellents and deterrents, oviposition stimulants, short- and long-range sex pheromones, and defensive substances. Emerging generalities are that attractants tend to be monoterpenoids and phenolic esters; oviposition stimulants are monoterpenoids and flavanoids; short-range sex pheromones are female-produced, methyl-branched cuticular hydrocarbons; and long-range sex pheromones are male-produced -hydroxy ketones and (,)-diols ranging in length from 6 to 10 carbons. The latter compounds appear to originate from glands in the male thorax; putative defensive substances originate from metasternal secretory pores or mandibular glands. In one unusual case, a flightless, subterranean female that attacks sugar cane produces a sex pheromone that is derived from the amino acid isoleucine. With significantly more than 35,000 species of Cerambycidae worldwide, these generalities will be subject to change as more species are examined. Addendum The authors would like to point out that the electronic version is more accurate than the printed version.  相似文献   
42.
预酸析-厌氧流化床处理碱法草浆黑液的研究   总被引:10,自引:0,他引:10  
对预酸析多孔高分子载体固定化微生物厌氧流化床(AFB)处理碱法草浆黑液的效能进行了研究.结果表明,采用酸析预处理,去除了黑液中大部分难生化降解的高分子物质后,AFB的厌氧消化潜能得到充分发挥.预酸析AFB处理比直接AFB处理更为有利.对黑液中木质素的化学性质研究表明,厌氧处理前后的黑液中木质素分子的基本结构单元保持不变,但分子量大的木质素有向小分子转化的趋势.通过扫描电镜观察,除了产甲烷菌外,还发现了硫酸盐还原菌和硫细菌.  相似文献   
43.
Under the project of evaluating the health status of the employees of CHEMKO factory (East Slovakia) which produced PCBs between 1955 and 1985, the level of β2-microglobulin (β2-m) was measured in the serum of 242 subjects from CHEMKO (Group A) and two control groups from much less polluted areas: 1. 277 females from a small mountainous village (Group B), 2. 179 adults from the area of a large city of Ko ice (Group C). The level of thymidine kinase (TK) was measured in the groups A and B only. In addition, age-matched groups of 155 women each from all areas were evaluated. In both the whole group and the age-matched group from CHEMKO the level of β2-m was significantly lower (P<0.001) than that in the respective control groups, while no difference was found in the level of TK. In conclusion, it is suggested that the decrease of β2-m in CHEMKO employees might be related to the immunotoxic effects of organochlorines.  相似文献   
44.
Subbiah D  Kala S  Mishra AK 《Chemosphere》2005,61(11):1580-1586
The fluorescence spectroscopic behavior of bromadiolone (anticoagulant rodenticide), a substituted 4-hydroxycoumarin derivative, was investigated in water and in organized media like micelles and cyclodextrins. A detailed study on various photophysical parameters like fluorescence intensity (IF), quantum yield (), lifetime (τ) and steady state fluorescence anisotropy (r) of bromadiolone in aqueous and in organized media was carried out. Bromadiolone in aqueous solution was observed to be in an aggregated state, thereby showing weak emission due to self-quenching. Marked enhancement of fluorescence intensity was observed in organized media like micelles and β-cyclodextrin. A preliminary investigation has been done to find out whether this enhancement of fluorescence can be used to develop a sensitive analytical method for determination of bromadialone in aqueous media. A linear relationship between the fluorescence intensity and concentration of bromadiolone was observed in the range of 0.15–7.9 μg ml−1 in cetyltrimethylammonium bromide (CTAB) and 0.5–26.4 μg ml−1 in β-cyclodextrin medium. The lower detection limit was found to be 37 ng ml−1 in presence of CTAB and 23 ng ml−1 in β-cyclodextrin. Comparison with 4-hydroxycoumarin, an unsubstituted analogue, was made.  相似文献   
45.
我国东南地区台风降水显著,但对这种强降水事件中的稳定同位素研究较少,限制了对短时间极端降水稳定同位素变化过程和影响因素的认识。论文根据2015年9月28日至29日第21号台风“杜鹃”两次登陆(台湾宜兰、福建莆田)前后台北、福州两地气象数据和降水稳定同位素数据,分析了此次台风的降水稳定同位素变化特征及影响因素。台风期间,两地降水δ18O波动范围为-3.4‰~-15.0‰,变化幅度达11.6‰。台风前端和尾端两地降水同位素值相对偏正,平均值为-4‰~-6‰而台风中端两地降水同位素值极其偏负,平均值分别为-12.4‰和 -13.2‰。台风前端与尾端降水同位素值偏正,水汽受蒸发效应影响明显;而台风中端降水δ18O值极端偏负主要受“云雨区效应”的影响,即云雨区气流急剧上升,水汽在过饱和环境中快速凝结降落,受动力分馏作用小,降水δ18O极端偏负。结合降水δ18O变化特征、过量氘及模拟水汽轨迹,得到台风“杜鹃”降水主要的水汽来源为西太平洋海域。  相似文献   
46.
Perfluorooctane sulfonate (PFOS), as a potential persistent organic pollutant, has been widely detected in water environments, and has become a great concern in recent years. PFOS is very stable and difficult to decompose using conventional techniques. Sorption may be an attractive method to remove it from water. In this study, the molecularly imprinted polymer (MIP) adsorbents were prepared through the polymerization of 4-vinylpyridine under different preparation conditions in order to remove perfluorooctane sulfonate (PFOS) from water. The MIP adsorbents using perfluorooctanoic acid (PFOA) as the template had good imprinting effects and could selectively remove PFOS from aqueous solution. The sorption behaviors including sorption kinetics, isotherms, and effect of pH, salt, and competitive anions were investigated. Experimental results showed that the sorption of PFOS on the MIP adsorbents was very fast, pH-dependent, and highly selective. The achieved fast sorption equilibrium within 1 h was attributed to the surface sorption on the fine adsorbents. The sorption isotherms showed that the sorption selectivity of PFOS on the MIP adsorbents decreased at high PFOS concentrations, which may be due to the double-layer sorption and the formation of PFOS micelles on the sorbent surface. The sorption of PFOS on the MIP adsorbents was mainly dominated by the electrostatic interaction between the protonated vinylpyridine on the adsorbent surface and the anionic PFOS. The prepared MIP adsorbents can potentially be applied in water and wastewater treatment for selective removal of PFOS.  相似文献   
47.
本文对一体式膜生物反应器中胞外聚合物(EPS)的提取方法及其对膜污染的影响进行了试验研究,结果表明:胞外聚合物提取方法中,物理方法中的热提法较为简便易行,适当的振荡频率可以提高提取效率,超声波法(30 W-6 min)是可行的提取方法,硫酸法、EDTA法和甲醛-NaOH法联用可以用于活性污泥提取EPS,其中甲醛-NaO...  相似文献   
48.
根据材料性能的要求,选择环氧树脂为粘合剂,低分子聚酰胺为固化剂,石粉,石英砂,玻璃纤维3种物质为填料,根据优化的配方制成一种高分子复合材料,该材料的硬度约为240HB左右,冲击强度约为30kg·cm/cm^2,均接近于某些金属材料的指标,易成型,并且成本较低,可以用来代替纺织厂有梭织机的某些受撞击比较严重的金属部件,具有广泛的应用价值。  相似文献   
49.
接枝羧基壳聚糖的合成及其对重金属离子的吸附性能   总被引:31,自引:3,他引:28  
以壳聚糖为基体,经环氧氯丙烷交联,制备了水不溶性交联壳聚糖,然后以Fe^2+-H2O2为引发剂,将丙烯腈单体接枝到CCTS分子骨架上,经皂化制得了水溶性接枝羧基壳聚糖聚合物。  相似文献   
50.
胞外聚合物结合磷效能的研究   总被引:3,自引:2,他引:3  
以实验SBR反应器的活性污泥为研究对象,探讨了超声波-树脂法提取EPS的方法与程序;以5种不同来源的活性污泥为研究对象,考察了EPS结合磷的效能.结果表明,超声波-树脂法分离EPS和细菌细胞的较优程序为:采用21kHz、40W超声波作用60mL污泥2min(VSS约为8000mg·L-1);然后,投加80g·g-1(以...  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