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971.
Hien PD Hiep HT Quang NH Huy NQ Binh NT Hai PS Long NQ Bac VT 《Journal of environmental radioactivity》2002,62(3):295-303
The 137Cs inventories in undisturbed soils were measured for 292 locations across the territory of Vietnam. The logarithmic inventory values were regressed against characteristics of sampling sites, such as geographical coordinates, annual rainfall and physico-chemical parameters of soil. The regression model containing latitude and annual rainfall as determinants could explain 76% of the variations in logarithmic inventory values across the territory. The model part was interpreted as the logarithmic 137Cs deposition density. At the 95% confidence level, 137Cs deposition density could be predicted by the model within +/- 7% relative uncertainty. The latitude mean 137Cs deposition density increases northward from 237 Bq m(-2) to 1097 Bq m(-2), while the corresponding values derived from the UNSCEAR (1969) global pattern are 300 Bq m(-2) and 600 Bq m(-2). High 137Cs inputs were found in high-rainfall areas in northern and central parts of the territory. 相似文献
972.
973.
On 26 August 1983, a single case of paralytic shellfish-poisoning (PSP) was reported in Davao City, Philippines. The poisoning was traced to ingestion of the green mussel Perna viridis Linnaeus, gathered from Balete Bay, Mati, Davao Oriental. Phytoplankton and zooplankton analyses on 12 October 1983 (47 d later), revealed the presence of the dinoflagellate Pyrodinium bahamense var. compressa, a cause of a series of red tides in the early and middle 1970's in Papua New Guinea, Sabah, and Brunei, and more recently, in Palau, and Western Samar and Leyte, Philippines. The dinoflagellate was not dominant; in fact the enumeration showed greater numbers of Ceratium sp., another dinoflagellate. Quantification of the neurotoxin by the standard mouse assay revealed a very high potency. Mussels collected from a new raft (transplanted in May 1983) had a toxicity of 7 960 mouse units (MU) per 100 g-1 meat. Those from an old raft (transplanted in May 1982) had a toxicity of 9 620 MU per 100 g-1 meat.SEAFDEC Contribution No. 145 相似文献
974.
Sohel Q. Saikat Joy E. Carter Aradhana Mehra Barry Smith Alex Stewart 《Environmental geochemistry and health》2004,26(3-4):395-401
Endemic goitre was prevalent in the population of Derbyshire in the UK for many centuries until it declined from the 1930s. A contemporary medical survey showed that endemicity of goitre was particularly higher in the Carboniferous limestone areas of the Derbyshire-Peak District. Unlike classical goitrous areas of the world, where the distribution of goitre has been found to be related to the iodine content in the environment, there is no such relationship reported for the Derbyshire-Peak District area. The present study reviews the presence of endemic goitre in this area with reference to iodine in different environmental media using past and present data. In comparison with the world average values, the iodine contents in the soil and sediment in the Peak District are not deficient, but compared to England, Wales and Scotland averages, these levels are low. As no information on the mobility and bioavailability of iodine of this area is available, a cautious approach is necessary before any assumption is made on the aetiology of endemic goitre. The study also discusses some hypotheses relating to the possible cause of endemic goitre in the limestone areas. Further research needs are suggested depending on the land use and geochemistry of the Peak District to determine the underlying causes of the former endemic goitre in this area. 相似文献
975.
经济植物复层栽培对三峡库区水土保持和移民经济的作用 总被引:9,自引:1,他引:8
三峡库区森林覆盖率低,水土流失严重。三峡工程兴建后,由于大量耕地被淹,移民后靠,库区的生态环境与移民经济之间的矛盾将会更加突出。本文提出了经济植物复层栽培方法,对其在减少库区水土流失、改善库区生态环境和解决库区移民经济方面的作用作了全面的论述。经济植物复层栽培是解决三峡库区生态环境和移民经济的基本途径,采用扩大种植农作物的方法来解决三峡库区移民经济问题将会加剧水土流失,使生态环境更加恶化。 相似文献
976.
阐述了新型SXD水力旋流沉淀器的工作原理及结构特点,并从理论和实际应用两方面分析了影响水力旋流器处理效果的因素,评价了其在精对苯二甲酸废水处理中的性能。 相似文献
977.
铬渣中Cr(Ⅵ)制取铬黄颜料的资源化技术研究 总被引:3,自引:0,他引:3
用蒸馏水在直径52 mm和80 mm的有机玻管中淋浸风化铬渣,在渣水比为250 g/200mL、500 g/400 mL和750 g/600 mL的3种方案中,750 g/600 mL的效果最佳.在2种不同管径装置中,可分别得到Cr(Ⅵ)总溶出率为94.0%、98.7%的良好淋浸效果.将含Cr(Ⅵ)的淋滤液替代商品重铬酸钠成功地制备出柠檬铬黄、中铬黄、浅铬黄,PbCrO4含量指标符合国标要求.相对于铅盐、Na2CrO4的理论反应用量,Cr(Ⅵ)浓度为26.21 g/L时,不仅可获取理想的铬黄生成量,而且可使沉淀分离液中检不出Cr(Ⅵ)残留量,但高于此浓度则会出现Cr(Ⅵ)残留.理论值1.15倍的铅盐用量可使Cr(Ⅵ)沉淀完全,铬黄达最高产率.廉价矿物材料改性磷灰石等可用于外排废液中Pb2+的吸附去除,以控制二次污染.利用铬渣中Cr(Ⅵ)溶出液直接制取铬黄颜料,可为铬渣资源化处理开辟一条新途径并获得明显的经济效益. 相似文献
978.
Yun Heejeong Kang Dongjin Kang Youngeun 《Environment, Development and Sustainability》2022,24(1):502-526
Environment, Development and Sustainability - Since demand for outdoor recreation in forests has been increasing, a structural planning framework for sustainable use while minimizing ecosystem... 相似文献
979.
980.
Herein,palygorskite(PAL)was activated via a simple hydrothermal process in the presence of ammonium sulfide,and the effects of activation on the microstructure,physico-chemical feature and adsorption behaviors of PAL were intensively investigated.The hydrothermal process evidently improved the dispersion of PAL crystal bundles,increased surface negative charges and built more active –Si–O-groups served as the new"adsorption sites".The adsorption property of the activated PAL for Methyl Violet(MV)was systematically investigated by optimizing the adsorption variables,including p H,ionic strength,contact time and initial MV concentration.The activated PAL exhibited a superior adsorption capability to the raw PAL for the removal of MV(from 156.05 to 218.11 mg/g).The kinetics for MV adsorption followed pseudo second-order kinetic models,while the isotherm and thermodynamics results showed that the adsorption pattern well followed the Langmuir model.The structure analysis of PAL before and after adsorption demonstrated that electrostatic interaction and chemical association of –X–O-are the prominent driving forces for the adsorption process. 相似文献