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551.
关于消费者对转基因农产品认知的调查 总被引:8,自引:0,他引:8
调查发现有不少声称调查前就对转基因农产品“知道一点”,但了解的程度却有很大差别,其实更多的人并不真正了解,在对待基因农产品的态度上表现出相当的规律性:虽然都比较关注对生产转基因农产品给农民带来的收入,但更多的是关注对生态环境和人体健康的影响,希望加强管理。不同年龄、婚姻状态、性别和不同收入水平的人对转基因农产品的认知程度和态度虽然有很大程度的相似性,但也有相当程度的不同。 相似文献
552.
旅游业可持续发展的指标体系研究 总被引:22,自引:1,他引:21
牛亚菲 《中国人口.资源与环境》2002,(6)
本文提出旅游业可持续发展指标体系的构建思路 ,指出指标体系应以可持续发展的社会、经济和环境多元目标为标准 ,全面衡量旅游业可持续发展水平、可持续发展能力和可持续发展的协调性。文章给出可持续旅游指标体系的 4个层 :状态层、诊断层、趋势层和目标层 ,并在建立指标体系基础上构筑可持续旅游目标判断模型 相似文献
553.
Nanoscale zerovalent copper supported on a cation resin was successfully synthesized to enhance the removal of carbon tetrachloride (CCl(4)) from contaminated water. The use of the cation resin as a support prevents the reduction of surface area due to agglomeration of nanoscale zerovalent copper particles. Moreover, the cation resin recycles the copper ions resulting from the reaction between CCl(4) and Cu(0) by simultaneous ion exchange. The decline in the amount of CCl(4) in aqueous solution results from the combined effects of degradation by nanoscale zerovalent copper and sorption by the cation resin; thus the amount of CCl(4) both in aqueous solution and sorbed onto the resin were measured. The pseudo-first-order rate constant normalized by the surface-area and the mass concentration of nanoscale zerovalent copper (k(SA)) was 2.1+/-0.1 x 10(-2)lh(-1)m(-2), approximately twenty times that of commercial powdered zerovalent copper (0.04 mm). Due to the exchange between Cu(2+) and the strongly acidic ions (H(+) or Na(+)), the pH was between 3 and 4 in unbuffered solution and Cu(2+) at the concentration of less than 0.1 mg l(-1) was measured after the dechlorination reaction. In the above-ground application, resin as a support would facilitate the development of a process that could be designed for convenient emplacement and regeneration of porous reductive medium. 相似文献
554.
Jiewei Liu Junwei M Yanzhong Liu Ya Yang Dongbei Yue Hongtao Wang 《环境科学学报(英文版)》2014,26(10):2076-2083
The optimized production of a novel bioflocculant M-C11 produced by Klebsiella sp. and its application in sludge dewatering were investigated. The optimal medium carbon source,nitrogen source, metal ion, initial pH and culture temperature for the bioflocculant production were glucose, NaNO3, MgSO4, and pH 7.0 and 25°C, respectively. A compositional analysis indicated that the purified M-C11 consisted of 91.2% sugar, 4.6% protein and 3.9% nucleic acids(m/m). A Fourier transform infrared spectrum confirmed the presence of carboxyl, hydroxyl,methoxyl and amino groups. The microbial flocculant exhibited excellent pH and thermal stability in a kaolin suspension over a pH range of 4.0 to 8.0 and a temperature range of 20 to 60°C.The optimum bioflocculating activity was observed as 92.37% for 2.56 mL M-C11 and 0.37 g/L CaCl2 dosages using response surface methodology. The sludge resistance in filtration(SRF)decreased from 11.6 × 1012 to 4.7 × 1012m/kg, which indicated that the sludge dewaterability was remarkably enhanced by the bioflocculant conditioning. The sludge dewatering performance conditioned by M-C11 was more efficient than that of inorganic flocculating reagents,such as aluminum sulfate and polymeric aluminum chloride. The bioflocculant has advantages over traditional sludge conditioners due to its lower cost, benign biodegradability and negligible secondary pollution. In addition, the bioflocculant was favorably adapted to the specific sludge pH and salinity. 相似文献
555.
运用室内外环境监测与问卷调查法相结合的研究方法,对北京市某社区33名患心血管疾病的老年人夏季PM2.5、CO的暴露特征作了研究评价.结果表明,老年人夏季PM2.5、CO的24h个体平均暴露浓度分别为89.6μg/m3,1.9×10-6.PM2.5室内外浓度呈现明显的时间变化特征,并受到气象因素及室内外源排放的共同影响.对老年人群室内外与固定站点CO、PM2.5质量浓度变化的相关性分析显示,室外及固定站点的PM2.5浓度受区域污染源影响较大,CO浓度受局地源影响较大;大气PM2.5可能是影响该社区老年人健康的主要污染物. 相似文献
556.
557.
558.
Hongyuan Wang Xiaolu Jiang Ya He Huashi Guan 《Frontiers of Environmental Science & Engineering in China》2009,3(2):194-199
Four typical coastal sites (rocky shore, sandy shore, mud flat shore, and artificial harbor) at the Yellow Sea were chosen
to investigate the spatial and seasonal variations in bacterial communities. This was accomplished by using terminal restriction
fragment length polymorphism (T-RFLP) analysis of PCR amplified 16S rDNA fragments. Two kinds of tetrameric restriction enzymes,
HhaI and MspI, were used in the experiment to depict the bacterial community diversity in different marine environments. It was found
that the community compositions digested by the two enzymes separately were different. However, the results of bacterial community
diversity derived from them were similar. The MDA analysis results of T-RFLP profiles coming from HhaI and MspI both exhibited a significant seasonal community shift for bacteria and a relatively low spatial variation among the four
locations. With HhaI as the sample, the pair wise T-tests also revealed that variations were minor between each pair of marine environments, with R ranging from 0.198 to 0.349. However, the bacterial community structure in the mud flat site depicted a larger difference
than each of the other three sites (R ranging from 0.282 to 0.349). 相似文献
559.
An intensive sampling program had been undertaken in autumn (October, 2008) and winter (December, 2008 and January, 2009)
at urban (Xiamen University and Xianyue residential area), suburban (Institute of Urban Environment), industrial area (Lulian Hotel)
and background (Tingxi Reservoir) in Xiamen, Fujian Province, to characterize the atmospheric concentration and gas-particle phase
partitioning of PAHs. The average concentration of total PAHs in winter was almost 1.7 times higher than those in autumn. The log
scale plot of Kp versus sub-cooled liquid vapor pressure (P0
L) for all the data of autumn and winter season samples gave significantly
di erent slopes. The slope for the winter samples (–0.72) was steeper than that for the autumn samples (–0.58). The partitioning results
indicated that slope values varied depending on characteristics of specific site, source region and meteorological conditions which
play important roles in the partitioning of PAHs. In addition, local emission sources had a stronger e ect on partitioning results than
long-transported polluted plume. The sources of PAHs in five sampling sites in Xiamen also have been discussed initially. Diagnostic
ratios showed that the primary source of PAHs in urban, suburban and industrial area was from vehicle exhausts. While emission from
petrochemical factory and power plant was another main contributor to industrial area. 相似文献
560.