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391.
392.
海水中石油类国标分析方法存在的问题及改进建议 总被引:1,自引:0,他引:1
当前海水石油类分析三种国标方法存在代表性和适用性不足的问题,不同方法的数据间缺乏可比性,给政府和民众控制水体污染、评价水质状况带来偏差和不便。建议国家相关部门修订海水石油类分析方法,将水质石油类分析国标方法统一为红外分光光度法。通过海水样品加标实验验证了该方法的可行性,实际操作简便、准确。 相似文献
393.
为测定含大量干扰离子的水样中镍的浓度,提出一种改进的分光光度法。即以多种物质的吸光曲线回归方程,将实时测得的水样吸光度分解成多种物质的吸光度,利用多元一次方程进行求解并计算出浓度的方法。新方法在不进行修正时,对含Cr6+干扰的水样Ni2+测定的结果,误差较小。多组分的水样测量吸光度误差较大,通过引入修正系数修正后误差大幅下降。方法中Ni2+、Fe3+的吸光度与显色时间基本无关;而对于Mn2+、Cu2+和Cr6+,显色时间应控制在0.5~2.5 min内或10 min外,以保证测得吸光度值的稳定与准确。对组成不同的含Mn2+和Fe3+水样测得的Ni2+浓度分析,变异系数(CV)4.74%,检出限为0.275 mg/L,精确度和精密度较好。同时,这种规避方法还具有其他作用,可以在分析组分的同时粗略算出含量。 相似文献
394.
A highly sensitive catalytic procedure for the determination of ultratrace chromium(VI) was developed based on its catalytic effect on the oxidation of gallocyanine by hydrogen peroxide in hexamine‐hydrochloric acid buffer solution. The reaction was followed spectrophotometrically by measuring the rate of change in the absorbance at 620 nm. The apparent active energy of the catalytic reaction is 6.84 kJ . mol‐1. The calibration graph is linear for 0–150 ng.ml‐1, and the detection limit is 0.8 ng.ml‐1. Most foreign ions have no interfering effect on the determination of chromium(VI) except for Al3+, Cu2+, Fe3+and Fe2+. The interference of Al3+ is eliminated by masking with F‐, and those of Cu2+, Fe3+ and Fe2+ are eliminated by adding appropriate amount of EDTA. The present procedure had been used for the determination of trace chromium(VI) in lake water, mine water and electroplating wastewater, and the results were satisfactory. 相似文献
395.
Manuel H. Barcelo-Quintal Maria C. Cebada-Ricalde Angel R. Trejo-Irigoyen Reyna B. Rendon-Osorio Jose A. Manzanilla-Cano 《Journal of environmental science and health. Part. B》2013,48(2):120-126
Kinetic studies of endosulfan photochemical degradation in controlled aqueous systems were carried out by ultraviolet light irradiation at λ = 254 nm. The photolysis of (α + β: 2 + 1) endosulfan, α-endosulfan and β-endosulfan were first-order kinetics. The observed rate constants obtained from linear least-squares analysis of the data were 1 × 10?4 s?1; 1 × 10?4 s?1; and 2 × 10?5 s?1, respectively, and the calculated quantum yields (φ) were 1, 1 and 1.6, respectively. Preliminary differential pulse polarographic (DPP) analysis allowed to observe the possible endosulfan photochemical degradation pathway. This degradation route involves the formation of the endosulfan diol, its transformation to endosulfan ether and finally the ether's complete degradation by observing the potential shifts. 相似文献
396.
Production and use of engineered nanoparticles, such as titanium dioxide nanoparticles (nTiO2), is increasing worldwide, enhancing their probability to enter aquatic environments. However, direct effects of nTiO2 as well as ecotoxicological consequences due to the interactions of nTiO2 with environmental factors like ultraviolet (UV) irradiation on representatives of detrital food webs have not been assessed so far. Hence, the present study displayed for the first time adverse sublethal effects of nTiO2 at concentrations as low as 0.2 mg L−1 on the leaf shredding amphipod Gammarus fossarum both in presence and absence of ambient UV-irradiation following a 7-d exposure. In absence of UV-irradiation, however, the effects seemed to be driven by accumulation of nTiO2 at the bottom of the test vessels to which the gammarids were potentially exposed. The adverse sublethal and lethal effects on gammarids caused by the combined application of nTiO2 and ambient UV-irradiation are suggested to be driven by the formation of reactive oxygen species. In conclusion, both the accumulation of nTiO2 at the bottom of the test vessel and the UV induced formation of reactive oxygen species clearly affected its ecotoxicity, which is recommended for consideration in the environmental risk assessment of nanoparticles. 相似文献
397.
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399.
Sari Vilhunen Heikki Särkkä Mika Sillanpää 《Environmental science and pollution research international》2009,16(4):439-442
Background, aim, and scope The novel system of ultraviolet light-emitting diodes (UV LEDs) was studied in water disinfection. Conventional UV lamps,
like mercury vapor lamp, consume much energy and are considered to be problem waste after use. UV LEDs are energy efficient
and free of toxicants. This study showed the suitability of LEDs in disinfection and provided information of the effect of
two emitted wavelengths and different test mediums to Escherichia coli destruction.
Materials and methods Common laboratory strain of E. coli (K12) was used and the effects of two emitted wavelengths (269 and 276 nm) were investigated with two photolytic batch reactors
both including ten LEDs. The effects of test medium were examined with ultrapure water, nutrient and water, and nutrient and
water with humic acids.
Results Efficiency of reactors was almost the same even though the one emitting higher wavelength had doubled optical power compared
to the other. Therefore, the effect of wavelength was evident and the radiation emitted at 269 nm was more powerful. Also,
the impact of background was studied and noticed to have only slight deteriorating effect. In the 5-min experiment, the bacterial
reduction of three to four log colony-forming units (CFU) per cubic centimeter was achieved, in all cases.
Discussion When turbidity of the test medium was greater, part of the UV radiation was spent on the absorption and reactions with extra
substances on liquid. Humic acids can also coat the bacteria reducing the sensitivity of the cells to UV light. The lower
wavelength was distinctly more efficient when the optical power is considered, even though the difference of wavelengths was
small. The reason presumably is the greater absorption of DNA causing more efficient bacterial breakage.
Conclusions UV LEDs were efficient in E. coli destruction, even if LEDs were considered to have rather low optical power. The effect of wavelengths was noticeable but
the test medium did not have much impact.
Recommendations and perspectives This study found UV LEDs to be an optimal method for bacterial disinfection. The emitted wavelength was found to be an essential
factor when using LEDs; thus, care should be taken in selecting the proper LED for maximum disinfection. 相似文献
400.
采用分光光度法对工业总排放水中Cr6+进行不确定度评定,充分考虑测量重复性、标准溶液的配制、标准曲线的制备等因素对测量的影响,测得Cr6+的合成标准不确定度为0.023mg/L。 相似文献