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61.
以氯化铁为铁源,硼氢化钠为还原剂,壳聚糖为稳定剂,采用液相还原法制备壳聚糖稳定纳米铁(CS-Fe);并以氯化铁为铁源,硫酸镍为镍源,硼氢化钠为还原剂,壳聚糖为稳定剂,采用液相还原共沉淀法制备壳聚糖稳定纳米铁镍(CS-Fe/Ni)。通过SEM、EDS、XRD、FT-IR等表征手段,对所制备的CS-Fe和CS-Fe/Ni的形貌及微观结构进行表征,并以Co2+为目标去除物评价CS-Fe和CS-Fe/Ni的反应活性。初步研究表明,制成的CS-Fe含有单质纳米铁,颗粒多数以30~90 nm球形颗粒为主;而CS-Fe/Ni材料中含有纳米铁镍,颗粒多数以30~60 nm球形颗粒为主;在相同的实验条件下,反应60 min,CS-Fe/Ni对Co2+的去除率高达100%,但是CS-Fe仅为88%,即CS-Fe/Ni对Co2+的去除率比CS-Fe高。 相似文献
62.
We show that uloborid spiders, which lack the poison glands typical of nearly all other spiders, employ thousands of wrapping movements with their hind legs and up to hundreds of meters of silk line to make a shroud that applies substantial compressive force to their prey. Shrouds sometimes break the prey’s legs, buckle its compound eyes inward, or kill it outright. The compressive force apparently results from the summation of small tensions on sticky lines as they are applied to the prey package. Behavioral details indicate that wrapping is designed to compact prey; in turn, compaction probably functions to facilitate these spiders’ unusual method of feeding. This is the first demonstration that prey wrapping by spiders compacts and physically damages their prey, rather than simply restraining them. 相似文献
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64.
本文以福建省龙海市为例,分析了龙海市农业发展优势与存在的问题,提出了建设海峡西岸高效持续农业示范区的基本思路与技术对策 相似文献
65.
PIERRE CH. A. LEGOUX 《Natural resources forum》1981,5(2):167-179
This article discusses the legal criteria of a mining investment decision - the legal status of investments, fiscal regime and mining legislation. The importance of the security of tenure of mining titles and of the stability of the terms and conditions, as stated from the inception, is emphasized, and the concepts of state sovereignty, state ownership of mineral deposits and state participation in mining ventures are considered. The preference for legalistic solutions rather than ad hoc contracts is stated, and a brief review of the various types of mining agreements is given. Cet article analyse les critères juridiques de la decision concernant l'investissement minier: statut juridique des investissements, régime fiscal et legislation minière. L'importance de la sécurité de la concession minière et la garantie des clauses de contrats est mise en evidence. L'article considère également les concepts de souveraíneté de l'Etat, la propriété étatique des dépôts minéraux et la participation de l'Etat dans la recherche minérale. L'auteur indique sa préférence pour des solutions juridiques plutôt que des contrats particuliers et passe brièvement en revue les différents types d'accords miniers. Este artículo analiza los criterios legates empleados en la toma de decisiones sobre inversión minera: estado legal de la inversión, régimen fiscal y legislación minera. Se da énfasis a la importancia de la seguridad de posesión de los títulos mineros, la estabilidad de las condiciones iniciales de contrato y se consideran también los conceptos de soveranía del estado, propiedad estatal de los depósitos mineros y la participación del estado en la actividad minera. Se indica la preferencia por las soluciones a través de leyes en vez de contratos ad hoc y se revisan brevemente varios tipos de acuerdos mineros. 相似文献
66.
Ngai Weng Chan 《Disasters》1997,21(3):206-222
Institutional aspects of flood hazards significantly affect their outcomes in Malaysia. Institutional arrangements to deal with floods include: legislative activity, organisational structures, attitudes and sub-culture, and policies and instruments. When assessed in terms of four specific criteria, institutional aspects of flood hazards are found to be largely inadequate. Disaster reduction programmes are over-dependent on a reactive approach based largely on technology and not even aimed at floods specifically. Structual flood reduction measures are the predominant management tool and, although the importance of non-structural measures is recognised, thus far they have been under-employed. Current laws and regulations with regard to flood management are also insufficient and both the financial and human resources of flood hazard organisations are generally found to be wanting. Finally, economic efficiency, equity and public accountability issues are not adequately addressed by institutional arrangements for flood hazards. 相似文献
67.
Climatic change will result in great changes in vegetation. In this paper, a biogeographical model, the BIOME1, was used to
predict potential vegetation distribution in China under climate change. Firstly, the BIOME1 was validated according to the
climate–vegetation relationships in China. Kappa statistics showed that the validated BIOME1 was able to capture the geographical
patterns of vegetation more accurately. Then, the validated BIOME1 was used to predict the distribution of vegetation of China
under two climatic scenarios produced by a Regional Circulation Model, RegCM2/CN. The simulation results showed obvious northward
shifts of the boreal, temperate deciduous and evergreen and tropical forests, a large expansion of tropical dry forest/savanna
and reduction of tundra on the Tibetan Plateau. Three vulnerable regions sensitive to climate changes are pointed out, i.e.,
Northern China, the Tibetan Plateau and Southwestern China (mainly Hengduan Mountains in Yunnan Province and west of Sichuan
Province). In recent decades, China has experienced dramatic industrialization and population growth, which exert strong pressure
on the environment of China. The consequences of climate changes warrant more attention for maintaining a sustainable environment
for China. 相似文献
68.
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70.
Determination of polybrominated diphenyl ethers (PBDEs) in fish samples from rivers and estuaries in Taiwan 总被引:2,自引:0,他引:2
Polybrominated diphenyl ethers (PBDEs) have been used extensively over the past two decades as flame retardants in many types of polymers, and have been found to be a class of contaminants of concern. Measurements of PBDEs in various environmental matrices from Sweden, Holland, Japan, North America, and elsewhere have been reported. We report data of PBDEs in fish samples taken from six rivers and three estuaries in Taiwan. Seven PBDE congeners were observed in all sixty samples. BDE-47 was found to be the dominant congener in all waters, and BDE-154 contributed more than BDE-99 and BDE-100. Nonetheless, BDE-154 and BDE-183 were the predominant congeners in some species studied. These results are somewhat different from those from other countries, where the pattern is typically BDE-47 > 99 >100 >154, 153, and is postulated to be due to the extensive use of octa-BDE rather than penta-BDE in Taiwan. The average concentration distribution across all samples of the sum of PBDE congeners ranged from 30.6 ng/g lipid to 281 ng/g lipid. The concentrations of PBDEs in fishes reported here are higher than those reported from European countries, but lower than those from the United States. 相似文献