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101.
Jimmie L. Thomas J. Paul Riley Eugene K. Israelsen 《Journal of the American Water Resources Association》1972,8(5):922-934
ABSTRACT. A hybrid computer program was developed to predict the water and salt outflow from a river basin in which irrigation is the major user of water. The model combines a chemical model which predicts the quality of water percolated through a soil profile with a general hydrologic model. The chemical model considers the reactions that occur in the soil, including the exchange of calcium, magnesium, and sodium cations on the soil complex, and the dissolution and precipitation of gypsum and lime. The chemical composition of the outflow is a function of these chemical processes within the soil, plus the blending of undiverted inflows, evaporation, transpiration, and the mixing of sub surface return flows with groundwater. The six common ions of western waters, namely calcium (Ca++), magnesium (Mg++), sodium (Na+), sulfate (SO4=), chloride (Cl?), and bicarbonate (HCO3?) were considered in the study. Total dissolved solids (TDS) outflow was obtained by adding the individual ions. The overall model operates on a monthly time unit. The model was tested on a portion of the Little Bear River basin in northern Utah. The model successfully simulated measured outflows of water and each of the six ions for a 24-month period. The usefulness of the model was demonstrated by a management study of the prototype system. For example, preliminary results indicated that the available water supply could be used to irrigate additional land without unduly increasing the salt outflow from the basin. With minor adjustments the model can be applied to other hydrologic areas. 相似文献
102.
The economic inputs and outputs for the Possum Point Biological Station in Belize during 1990–1992 are described to illustrate
some aspects of an ecotourism operation. Eight hundred fifty-four people in 59 groups visited Possum Point during the study
period to tour rain forests, estuaries, and coral reefs. The economic input to Possum Point from these groups increased from
$74,552 in 1990 to $166,268 in 1992. Outputs were for license fees, capital improvements, goods and services, labor, fossil
fuels, and development of a historic sugar mill site. An annual donation was also made to a scholarship fund for local Belizean
students. The net cash balance of income and outputs changed from negative (−$6678) in 1990 to positive (+$4811) in 1992,
suggesting development of the economic operation. Possum Point meets the economic criteria for ecotourism by feeding back
some tourist monies for community and environmental support, particularly donations for the sugar mill site and the scholarship
fund. Most of the outputs from Possum Point (about 80%) were retained in the local economy through employment and purchases,
which have a positive influence on the local community. We conclude that ecotourism operations, such as Possum Point, offer
important sustainable development opportunities for Belize. 相似文献
103.
江静 《防灾科技学院学报》2005,7(2):107-110
本文采用次态卡诺图法对时序逻辑电路的功能进行分析,力图改进传统异步时序电路的分析方法,在保证分析结果正确无误的前提下,简化了常规分析方法中繁琐的步骤,更具有实用性。以一个8421BCD码表示的十进制异步减法计数器为例,给出各触发器状态方程的表达式,并用状态表、状态图分析其逻辑功能。 相似文献
104.
晋普山煤矿通风系统阻力测定与分析 总被引:3,自引:0,他引:3
矿井通风系统阻力测定是煤矿通风技术管理的重要内容,阻力的大小直接影响矿井的通风效果,笔者介绍了矿井通风阻力测定常用的几种方法,分别评述了其优缺点及适用条件,并根据晋普山煤矿通风系统实际情况,选用基点法对其通风阻力进行了测定,全面、准确地掌握了全矿井通风阻力分布情况,为今后进行通风系统调整,提供了有参考价值的基础数据资料。同时依据测定结果,对晋普山煤矿通风系统进行了合理分析。 相似文献
105.
106.
Rural and remote areas of countries such as Australia and the United States are less well‐resourced and often poorer than their city counterparts. When a disaster strikes, therefore, their long‐term recovery can be impeded by being situated ‘over the horizon'. Nonetheless, they are likely to enjoy higher social capital, with ‘locals’ banding together to help restore economic and social life in the wake of a calamitous incident. At the same time, a repeat of extreme events, springing in part from alteration to the landscape through intense human occupation, threatens to derail sustainable recovery processes everywhere, suggesting that renewed emphasis needs to be placed on preparedness. Improved metrics are also required, spanning both pre‐ and post‐disaster phases, to determine effectiveness. Moreover, a focus on the ‘hardening’ of towns offers a better return in limiting damage and potentially hastens the speed of recovery should these places later fall victim to extreme events. 相似文献
107.
108.
印制线路板废水处理工艺浅析 总被引:3,自引:1,他引:2
文章介绍了某企业的印制线路板废水处理工艺技术。由于废水的成分受生产线使用的各种配方药剂的影响,成分复杂多变,实施了分类收集,对不同生产过程的废水进行不同的预处理后再进行综合处理。工程实践表明,采用该工艺路线处理后的印制线路板废水出水水质达到了《广东省水污染物排放限值》(DB44/26--2001)一级标准,而且系统自动化程度高,操作方便,出水稳定。 相似文献
109.
废印制线路板真空热解产物分析 总被引:1,自引:0,他引:1
在自行设计的间歇式固定床真空热解装置中热解废印制线路板(PCB),对热解产物进行了分析.在热解温度为550 ℃、热解压力为20 kPa、恒温时间为60 min的条件下,得到的热解产物质量分数为:热解渣70%;热解油3%~4%;不可冷凝热解气26%~27%.经气相色谱-质谱联用(GC-MS)分析,热解油经常压蒸馏后得到的低沸点液态油中含有29种化合物,主要有苯酚、对异丙基酚、3-乙基酚、4-甲酚及2-溴苯酚,还含有少量含溴化合物和含氯化合物.热解油经简单的蒸馏就可达到回收酚类化合物的目的.热解渣经风选可实现铜与黏附有碳黑的玻璃纤维的分离,其中铜质量分数约30%,黏附有碳黑的玻璃纤维质量分数约70%. 相似文献
110.
Takanori Hino Ryuichi Agawa Youichi Moriya Minoru Nishida Yasuhiro Tsugita Takao Araki 《Journal of Material Cycles and Waste Management》2009,11(1):42-54
Waste printed circuit boards contain valuable metals such as Au, Pd, Ag, and Cu that can be reutilized and harmful elements
such as Pb, Br, and Cr that must be removed from the viewpoint of environmental conservation. In this research, we examined
a method that separates the materials from printed circuit boards contained in discarded personal computers. After cutting
the printed circuit boards to a size of 20 × 20 mm, they were heated at 873 K under an Ar atmosphere to remove organic resins
containing elements such as C, H, and N. After heat treatment, the printed circuit boards were crushed using a planetary ball
mill and the pulverized powders were filtered. The fraction with a granularity of greater than 250 μm was separated into magnetic
and nonmagnetic materials by a magnetic field. Because the fraction with a granularity of less than 250 μm contained 39 mass%
of C, it was heated at 1273 K in an atmosphere of 95% Ar and 5% O2 to allow carbon combustion to take place, followed by metal reduction processing at the same temperature in an atmosphere
of 97% Ar and 3% H2. The basicity of the resulting powder was adjusted and the powder was heated at 1773 K under an Ar atmosphere. The proposed
method separated the slag and metal, and 80% of the valuable metals contained in printed circuit boards could be collected. 相似文献