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961.
Through the lens of institutional economics, this paper reviews the reform and development experience in China's rural forest sector and discusses lessons that can be learned by China and other countries. We find that the impacts of the reforms, characterized by changes in forest tenures and market settings, hinge on how they are implemented. If farmers are granted not only land use rights but also liberalized market access, as shown in the northern farm region and the production of non-timber forest products, the incentive structure will be improved, and thus forest production will grow and producers and consumers will benefit. If the reforms are implemented in such a way as to cause market control and distortions, as witnessed in the southern traditional timber production region, the incentive structure will improve little. The chances for production increase will thus be diminished, making it difficult for producers and consumers to enhance their welfare. While tenure arrangements have evolved across the country in the 1990s, timber production in the south remains subject to allowable quota, cutting permit, government procurement, and heavy taxation. We wonder what the land use and tree ownership rights mean without the right to access market freely and fairly, and how practical it is to substitute government efforts for private initiatives in a successful forestry program. The time has come for Chinese policymakers to address these problems. 相似文献
962.
护岸堤林建设是建设是长江中上游防护林体系建设林种空间布局与配置不可缺少的有机组成部分,具沿江而布及成连续林带的特点。其发展的土地潜力取决于岸堤线长度、林带建设宽度和建设地带内的土地利用现状结构等三个因素。研究结果表明:长江中上游研究江段护岸堤林发展土地数量潜力规模为25123.4~41938.9hm2,其中需造林绿化的宜林荒地地(第一类潜力)为8214.5~13757.3hm2,需改造更新的疏灌林地和需加强抚育的未成林造林地(第二潜力)为5409.3~9015.5hm2,需退耕还林的耕地(第三类潜力)为11499.6~19166.1hm2。 相似文献
963.
当我们满怀激情翻开2005年的日历时,不经意地发现已进入海城地震成功预报30周年的门槛,令人们不能忘怀的是,当1975年2月4日7.3级地震强烈震撼着辽南大地时,面对灾区到处房倒屋塌的悲凉景象,震区人民并没有气馁,而是满怀豪情地抗震救灾、重建家园,描绘更为美好的建设蓝图。这种生动场面的出现是因为震前有了较为准确的地震预报。 相似文献
964.
新形势下改革和加强中国环境保护管理体制的思考 总被引:1,自引:0,他引:1
中国现行的环境保护管理体制已无法适应日益复杂化的环境问题,改革和强化环境保护管理体制已迫在眉睫.分析了中国进行环境保护管理体制改革的必要性,提出了改革和强化体制的总体目标和基本思路,进而从管理体系、法律体系、运行机制和能力建设等方面论述了改革和强化环境保护管理体制的建议对策. 相似文献
965.
Preeclampsia and intrauterine growth restriction (IUGR) are major contributors to perinatal mortality and morbidity worldwide. Both are characterized by impaired trophoblastic invasion of the maternal spiral arteries and their conversion from narrow muscular vessels to wide non-muscular channels. Despite improvement in the understanding of the pathophysiology of these conditions, ability to accurately identify pregnant woman who will develop them is limited. This greatly impairs the development and testing of preventive interventions. While different measures of placental dysfunction have been associated with increased risk for adverse pregnancy outcomes, the ability of any single one to accurately predict these outcomes is poor. Developing predictive tests is further challenged by difficulty in the timing of the measurements, as both the structural and biochemical characteristics of the placenta change with increasing gestational age. The ideal screening test would accurately predict the development of adverse pregnancy outcomes early enough to provide a window for preventive interventions. Improvement in ultrasound technology provides potentially useful novel tools for evaluating placental structure, but measuresments need to be standardized in order to be useful. Maternal serum analyte screening is a noninvasive test of placental biochemical function, but present serum marker alone is not sufficiently accurate to suggest its routine use in clinical practice. The use of first trimester biochemical markers in combination with uterine artery Doppler screening is promising as a potential screening tool. Prospective longitudinal studies using standardized methodology are necessary to further evaluate the choice of parameters and strategies of combination to achieve the best predictive models. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
966.
可燃气体检测报警联动排风控制系统具有手动、定时启动、自动启动和关闭轴流风机的功能,能及时排除工作场所内积聚的可燃气体,实现本质安全化. 相似文献
967.
968.
为有效降低废酸再生装置尾气污染物NOx浓度,中海炼化惠州炼化分公司在l万吨/年的废酸再生装置尾气进行了H2 O2脱硝中试试验,以H2 O2为氧化剂,以钠碱为吸收剂,采用部分烟气加温激活H2 O2,产生大量的活性基团,从而氧化尾气中的NOx,生成高价态的NOx,然后用碱液吸收.结果表明:NOx脱除效率受停留时间影响,当采用填料塔时,停留时间达到4 s,脱除效率达到18% ~21%;当采用填料-鼓泡工艺时,停留时间达到10 s~12 s,脱除效率可达到60%~70%,出口NOx浓度满足广东省地方排放标准要求. 相似文献
969.
Jingyong Liu Jiewen Fu Xun''an Ning Shuiyu Sun Yujie Wang Wuming Xie Shaosong Huang Sheng Zhong 《环境科学学报(英文版)》2015,35(9):43-54
The effects of different chlorides and operational conditions on the distribution and speciation of six heavy metals (Pb, Zn, Cr, Cu, Mn and Ni) during sludge incineration were investigated using a simulated laboratory tubular-furnace reactor. A thermodynamic equilibrium investigation using the FactSage software was performed to compare the experimental results. The results indicate that the volatility of the target metals was enhanced as the chlorine concentration increased. Inorganic-Cl influenced the volatilization of heavy metals in the order of Pb > Zn > Cr > Cu > Mn > Ni. However, the effects of organic-Cl on the volatility of Mn, Pb and Cu were greater than the effects on Zn, Cr and Ni. With increasing combustion temperature, the presence of organic-Cl (PVC) and inorganic-Cl (NaCl) improved the transfer of Pb and Zn from bottom ash to fly ash or fuse gas. However, the presence of chloride had no obvious influence on Mn, Cu and Ni. Increased retention time could increase the volatilization rate of heavy metals; however, this effect was insignificant. During the incineration process, Pb readily formed PbSiO4 and remained in the bottom ash. Different Pb compounds, primarily the volatile PbCl2, were found in the gas phase after the addition of NaCl; the dominant Pb compounds in the gas phase after the addition of PVC were PbCl2, Pb(ClO4)2 and PbCl2O4. 相似文献
970.
Energy consumption and carbon emission for tourism transport in World Heritage Sites: a case of the Wulingyuan area in China 下载免费PDF全文
Transport profoundly affects energy use and carbon dioxide emissions in the tourism sector. The Wulingyuan Scenic Area (WSA), a natural heritage destination in China, is chosen for the case study. The energy consumption and carbon emission of 10 types of tourism transportation modes at the destination are measured and analyzed using a bottom‐up approach for the period of 1979 to 2010. Scenarios were created to project the effects of single and multiple factors on energy consumption and carbon emission by tourism transportation during 2011‐2020. The results showed the following: (a) there is a large difference in energy consumption and carbon emission per capita and per kilometer per capita among the 10 vehicle modes; (b) the monthly energy consumption and carbon emission of tourism transportation differed significantly, the month with the highest (October) are respectively 6.8 and 4 times that of the lowest month (January); (c) the highest annual growth rate of energy consumption and carbon emission are respectively as 32.16% and 27.98% during 1979‐2010; and (d) the amount of energy consumption and carbon emission in the multiple factor scenarios are lower than that in the reference and single factor scenarios during 2011‐2020. 相似文献