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201.
This study investigated the possible effects of a commonly used foliar herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) formulation on medulla spinalis of lebistes. Fish were exposed to 2,4-D (15, 30, 45 mg L−1), behavioral changes were monitored. Fish were fixed, histopathological examination was carried out on sections taken from the upper parts of the fish body. Histopathology showed increase in neuronal loss, swelling indicating formation of intracellular edema, vacuolization noticed as the formation of vacuoles within or adjacent to cells, deformation in the Nissl granules, pyknosis and gliosis in medulla spinalis. Behavioral changes were decreased general activity, grouping, shortness in breath, sudden rotations and jumping, loss of equilibrium and colour. In conclusion, this commercial formulation of 2,4-D is considerably neurotoxic to lebistes. Fish constitute the last link in the chain of the feeding cycle in aquatic eco-system, number of studies investigating acute and chronic neurotoxicity of various herbicides in fish should be increased. 相似文献
202.
Huan Zhong 《Environmental pollution (Barking, Essex : 1987)》2009,157(3):981-986
This study compared the relative importance of three types of sorption (organic matter-particle, mercury-organic matter and mercury-particle) in controlling the overall mercury partitioning and bioavailability in sediments. We found that all three types of sorption were important for both inorganic mercury (Hg) and methylated mercury (MeHg). Mercury-particle sorption was more important than mercury-fulvic acid (FA) sorption in increasing the mercury concentrations with increasing aging. Bioavailability (quantified by gut juice extraction from sipunculans) was mainly controlled by mercury-particle sorption, while FA-particle and mercury-FA sorption were not as important, especially for MeHg. Bacterial activity also increased the partitioning of Hg or MeHg in the sediments and was further facilitated by the presence of organic matter. The bioavailability of Hg or MeHg from sediments was only slightly influenced by bacterial activity. This study highlights the importance of sorption from various sources (especially mercury-particle sorption) as well as bacteria in controlling the partitioning and bioavailability of Hg or MeHg in sediments. 相似文献
203.
Jan Bernd Barhorst Roland Kubiak 《Environmental science and pollution research international》2009,16(5):582-589
Background, aim and scope The use of sodium hypochlorite (HYP) in viticulture results in effluents which are contaminated with halogenated substances.
These disinfection by-products (DBPs) can be quantified as group parameter ‘adsorbable organic halogens’ (AOX) and have not
been determined in effluents of viticulture yet. The substances that are detected as AOX are unknown. The AOX can be composed
of harmless substances, but even toxic contaminants. Thus, it is impossible to assess ecological impacts. The aim of this
study is to determine the quantification of AOX and DBPs after the use of HYP. This will be helpful to reduce environmental
pollution by AOX.
Materials and methods The potential of HYP to generate AOX was determined in laboratory-scale experiments. Different model solutions were treated
with HYP according to disinfection processes in viticulture and conditions of AOX formation in effluents were simulated. AOX
were quantified using the flask-shaking method and identified DBPs were investigated by gas chromatography–mass spectrometry.
Results Treatment with HYP resulted in the formation of AOX. The percentage conversion of HYP to AOX was up to 11%. Most important
identified DBPs in viticulture are chloroform, dichloroacetic acid and trichloroacetaldehyde. In addition, the formation of
carbon tetrachloride (CT), 1,1,1-trichloropropanone, 2,4-dichlorobenzoic acid and 2-chloro-/2,4-dichlorophenylacetic acid
was investigated. It was demonstrated that reaction temperature, concentration of HYP and type of organic matter have important
influence on the formation of chlorinated DBPs.
Discussion The percentage conversion of HYP to AOX was similar to other published studies. Although a correlation of single compounds
and AOX is difficult, chloroform was the predominant AOX. Generation of the volatile chloroform should be avoided due to possible
adverse effects. The generation of dichloroacetic acid is of minor importance on account of biodegradation. Trichloroacetaldehyde
and 1,1,1-trichloropropanone are weak mutagens and their formation should be avoided.
Conclusions The generation of AOX and chlorinated DBPs can be minimised by reducing the concentrations of the organic materials in the
effluents. The removal of organic matter before disinfection results in a decreased formation of AOX. HYP is an effective
disinfectant; therefore, it should be used at low temperatures and concentrations to reduce the amount of AOX. If possible,
disinfection should be accomplished by the use of no chlorine-containing agents. By this means, negative influences of HYP
on the quality of wine can also be avoided.
Recommendations and perspectives Our results indicate that HYP has a high potential to form AOX in effluents of viticulture. The predominant by-products are
chloroform, dichloroacetic acid and trichloroacetaldehyde. In further research, wastewaters from a winery and the in- and
outflows of two sewage treatment plants were sampled during vintage and analysed. These results will be discussed in a following
paper. 相似文献
204.
A.A.L. Oiffer J.F. Barker F.M. Gervais K.U. Mayer C.J. Ptacek D.L. Rudolph 《Journal of contaminant hydrology》2009,108(3-4):89-106
An anaerobic plume of process-affected groundwater was characterized in a shallow sand aquifer adjacent to an oil sands tailings impoundment. Based on biological oxygen demand measurements, the reductive capacity of the plume is considered minimal. Major dissolved components associated with the plume include HCO3, Na, Cl, SO4, and naphthenic acids (NAs). Quantitative and qualitative NA analyses were performed on groundwater samples to investigate NA fate and transport in the subsurface. Despite subsurface residence times exceeding 20 years, significant attenuation of NAs by biodegradation was not observed based on screening techniques developed at the time of the investigation. Relative to conservative tracers (i.e., Cl), overall NA attenuation in the subsurface is limited, which is consistent with batch sorption and microcosm studies performed by other authors. Insignificant biological oxygen demand and low concentrations of dissolved As (< 10 µg L− 1) in the plume suggest that the potential for secondary trace metal release, specifically As, via reductive dissolution reactions driven by ingress of process-affected water is minimal. It is also possible that readily leachable As is not present in significant quantities within the sediments of the study area. Thus, for similar plumes of process-affected groundwater in shallow sand aquifers which may occur as oil sands mining expands, a reasonable expectation is for NA persistence, but minimal trace metal mobilization. 相似文献
205.
206.
厌氧序批式反应器内挥发性脂肪酸积累特性研究 总被引:1,自引:0,他引:1
小试规模的厌氧序批式反应器(ASBR),通过人工配水,研究了启动3个月时间以及一个运行周期内反应器内挥发性脂肪酸(VFA)的积累情况,并通过分析期间产甲烷活性的变化说明了控制VFA积累的重要性。经过近120 d的运行,乙酸和丙酸的最大比产甲烷活性分别提高了1.8和2.2倍,说明反应器的启动过程即是微生物群落的优化和选择的过程,ASBR的抗冲击的能力较强说明随启动的进行和种群的优化,活性污泥凝聚性能增强,对VFA的降解能力增强。 相似文献
207.
Dechlorination of polyvinyl chloride in NaOH/ethylene glycol solution by microwave heating 总被引:1,自引:1,他引:0
This study investigated the dehydrochlorination of flexible polyvinyl chloride (PVC) containing 59.2% PVC, 29.7% dioctyl phthalate
(DOP), and approximately 12% stabilizers. Flexible PVC was treated with NaOH/ethylene glycol (NaOH/EG) solutions at NaOH concentrations
in the range 0.5–4 mol/l and was heated in a microwave heater at a temperature between 100° and 160°C for 0–30 min. All chlorides
were completely eliminated by internal heating at 160°C using microwaves for 10 min in a 1 mol/l NaOH/EG solution, and the
residue was made up of hydrocarbons. The weight loss rate reached a maximum of 74.7% at a temperature of 160°C. It was discovered
that the use of microwaves significantly shortened the reaction time compared to using conventional electric heaters or other
external heating systems and also allowed the use of lower concentrations of NaOH.
Chemical Feedstock Recycling & Other Innovative Recycling Techniques 6 相似文献
208.
The Effect of Masterbatch Addition on the Mechanical, Thermal, Optical and Surface Properties of Poly(lactic acid) 总被引:1,自引:0,他引:1
F. Byrne P. G. Ward J. Kennedy N. Imaz D. Hughes D. P. Dowling 《Journal of Polymers and the Environment》2009,17(1):28-33
There has been considerable interest in the use of the biodegradable polymer poly(lactic acid) (PLA) as a replacement for
petroleum derived polymers due to ease of processability and its high mechanical strength. Other material properties have
however limited its wider application. These include its brittle properties, low impact strength and yellow tint. In an attempt
to overcome these drawbacks, PLA was blended with four commercially available additives, commonly known as masterbatches.
The effect of the addition of 1.5 wt% of the four masterbatches on the mechanical, thermal, optical and surface properties
of the polymer was evaluated. All four masterbatches had a slight negative effect on the tensile strength of PLA (3–5% reduction).
There was a four fold increase in impact resistance however with the addition of one of the masterbatches. Differential scanning
calorimetry demonstrated that this increase corresponded to a decrease in the polymer crystallinity. However there was an
associated increase in polymer haze with the addition of this masterbatch. The clarity of PLA was improved through the addition
of an optical brightener masterbatch, but the impact resistance remained low. The glass transition and melting temperatures
of PLA were not affected by the addition of the masterbatches, and no change was observed in surface energy. Some delay in
PLA degradation, in a PBS degradation medium at 50 °C, was observed due to blending with these masterbatches. 相似文献
209.
过氯乙烯滤膜采样-酸消解-钼蓝光度法测定磷酸雾 总被引:1,自引:0,他引:1
建立了过氯乙烯滤膜采样 -酸消解 -钼蓝分光光度法测定磷化车间磷酸雾的监测方法。实验室模拟采样的捕集效率为 95 7%~ 99 1 %。单个实验室对含 5μg和 1 5μg样品进行多次测定 ,其相对标准差小于 5% ,样品加标回收率为 98 2 %~ 1 0 0 5% ,方法检测限为 0 0 0 7mg/m3。对标样测定 ,结果均在给定值范围内。用该法与等离子发射光谱法(ICP)对 5个样品进行比对测定 ,结果均令人满意。 相似文献
210.
胭脂红酸分光光度法测定废水中硼 总被引:5,自引:0,他引:5
用胭脂红酸分光光度法测定废水中的硼,着重进行了方法的条件和干扰试验。方法检测限为0.063mg/L,线性范围为0.21mg/L-1.25mg/L。5个实验室对5.00mg/L硼标准样品测得重复性相对标准差为3.4%,再次性相对标准差为3.6%;相对误差为-0.8%-1.4%,回收率在95.2%-104.6%之间。 相似文献