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621.
1IntroductionSincethe1970s,theCFCsandHalonsemitedbyhumanhavebeenwidelythoughtassubstanceswhichmaycauseozonedepletioninstrato... 相似文献
622.
In order to provide further references for studing on the causes of Kaschin-Beck discase (KBD) and measuring for its prevention and treatment from a macroscopic view, we analyzed the natural growth and declineof KBD and the effects of selenium and humic acid on its occurrence from an epidemiologic angle. In this article through a retrospective survey on the spots of disease areas by comparison between a change in water sources and that without. It was proved that a change in water sources was an effective measure for the prevention of KBD occurrence, and the pathogenic factor of KBD was one (or several kinds) of organic compounds or active radicals related to water. 相似文献
623.
The reaction mechanism of 3-chlorophenol with OH, H in aqueous solution was studied by transient technology.The 3-chlorophenol aqueous solutions have been saturated with air or N2 previously.Under alkaline condition,the reaction of OH radical with 3-chlorophenol produces 3-chlorinated phenoxyl radical ,with the absorption peaks at 400 nm and 417nm.Under neutral condition,the reaction of OH radical with 3-chlorophenol produces OH-adduct with the maximal absorption at about 340 nm.And in acid solution,the reaction of H with 3-chlorophenol produces H-adduct with the maximal absorption at about 320nm.3-chlorophenol is compared with 4-and 2-chlorophenols from the free radical pathways.The results show that the positions of chlorine on the aromatic ring strongly influence the dehalogenation and degradation process. 相似文献
624.
StudyonthecementitiousnesofasbestostailingsLuZhongyuan,HuoJichuan,LiaoQilong,XiongYimouSouthwestInstituteofTechnology,Mia... 相似文献
625.
Lewis DJ Atwill ER Lennox MS Hou L Karle B Tate KW 《Environmental monitoring and assessment》2005,107(1-3):407-425
How and where to improve water quality within an agricultural watershed requires data at a spatial scale that corresponds with individual management decision units on an agricultural operation. This is particularly true in the context of water quality regulations, such as Total Maximum Daily Loads (TMDLs), that identify agriculture as one source of non-point source pollution through larger tributary watershed scale and above and below water quality investigations. We have conducted a systems approach study of 10 coastal dairies and ranches to document fecal coliform concentration and loading to surface waters at the management decision unit scale. Water quality samples were collected on a storm event basis from loading units that included: manure management systems; gutters; storm drains; pastures; and corrals and lots. In addition, in-stream samples were collected above and below the dairy facilities and from a control watershed, managed for light grazing and without a dairy facility or human residence and corresponding septic system. Samples were analyzed for fecal coliform concentration by membrane filtration. Instantaneous discharge was measured for each collected sample. Storm runoff was also calculated using the curve number method (SCS, 1985). Results for a representative dairy as well as the entire 10 dairy data set are presented. Fecal coliform concentrations demonstrate high variability both within and between loading units. Fecal coliform concentrations for pastures range from 206 to 2,288,888 cfu/100 ml and for lots from 1,933 to 166,105,000 cfu/100 ml. Mean concentrations for pastures and lots are 121,298 (SE=62,222) and 3,155,584 (SE=1,902,713) cfu/100 ml, respectively. Fecal coliform load from units of concentrated animals and manure are significantly more than units such as pastures while storm flow amounts were significantly less. Compared with results from earlier tributary scale studies in the watershed, this systems approach has generatedwater quality data that is beneficial for management decisions because of its scale and representation of current management activities. These results are facilitating on-farm changes through the cooperative efforts of dairy managers, regulatory agency staff, and sources of technical and financial assistance. 相似文献
626.
就当前建设项目对大气环境影响的环境质量评价中存在的问题,进行了论述,指出五个较突出的问题,以求改进,保证评价报告书的质量. 相似文献
627.
以顾桥煤矿坚硬顶板综采工作面工程地质条件为背景,运用理论分析、数值模拟和现场实测手段,分析了开采速度对工作面覆岩运动、围岩破坏、应力分布和液压支架承载特性的影响。研究结果表明:1个周期来压内工作面落煤引起的岩梁刚性回转下沉量是一定的,工作面作业循环时间引起的岩梁蠕变下沉量与岩梁刚性回转下沉量呈正比,加快工作面推进速度仅减少围岩体蠕变引起的岩梁下沉部分。工作面开采速度增加,覆岩塑性区发育范围减小,煤壁应力集中位置变浅、应力集中系数变小。工作面快速推进时,液压支架承载多为2次増阻和3次増阻,支架工作阻力较小;缓慢推进时,液压支架承载多为1次急增阻,载荷近似呈线性增长,支架工作阻力较大。 相似文献
628.
Xu Q Barrios CA Cutright T Newby BM 《Environmental science and pollution research international》2005,12(5):278-284
- Goal, Scope, Background. The traditional solution for keeping unwanted organisms from attaching to submerged surfaces is to
apply anti-fouling coatings. The most common antifoulant was tributyltin (TBT). TBT systems were highly effective but were
also toxic to non-target organisms. The use of the TBT based coatings will be completely banned by January 1, 2008. Therefore,
there is an urgent need to seek out suitable non-toxic alternatives.
Methods The aim of this work was to evaluate the effectiveness of capsaicin and zosteric acid as natural product antifoulants (NPAs)
in deterring bacterial attachment. Two fresh water bacteria systems Pseudomonas putida (Pp) and bacteria isolated from Lake
Erie (LE) were used to assess the attachment when the NPAs dispersed in the water. Effectiveness was ascertained based on
the decrease in microbial attachment, limited toxicity, and minimum alteration of the coatings properties.
Results and Discussion A significant inhibition of bacteria attachment was achieved when aqueous capsaicin concentration was increased from 0 to
40 mg/L. For instance, after 14 days the LE system depicted 93.5% and 98.5% less biofilm coverage for 20 mg/L and 40 mg/L
capsaicin, respectively when compared to systems without NPA. Biofilm coverage was reduced by 92.5% and 98.2%, respectively
with 50 mg/L and 500 mg/L zosteric acid.
Conclusions Both capsaicin and zosteric acid was effective at preventing bacteria attachment. As the NPA aqueous concentration increased,
biofilm formation decreased. Evaluating changes in aqueous pH, conductivity, dissolved oxygen, aqueous microbial population
and biofilm formation suggested that the primary antifoulant mechanism of these two NPAs was to block the bacteria's active
sites versus posing a lethal level.
Recommendation and Perspective From the attachment study, zosteric acid appeared to be more effective in preventing bacterial attachment when the NPAs were
dispersed in the aqueous environment. For practical applications, the antifoulant needs to be incorporated into a coating
and have a slow release rate. Thus the ability to successfully incorporate zosteric acid into a coating, without deterring
bacterial attachment, needs to be investigated. 相似文献
629.
630.
高铁酸钠电化学合成条件的研究 总被引:6,自引:0,他引:6
利用含铁材料为阳极,铜为阴极,NaOH溶液为电解液,于隔膜电解槽中电解制备高铁酸钠。探索了该工艺所必需的各种参数和反应条件,确定了隔膜材料,并对Na2FeO4浓度和电流效率的非一致性变化作出了解释。研究结果表明:在阳极距离为1.3cm(极距2.3cm)、阳极电解液浓度为14mol/L,阴极电解液浓度为4mol/L、温度为35℃、电压为8~9V时,电解2h后得到的Na2FeO4浓度为18.7g/L,电流效率为20%。 相似文献