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251.
Alpina Begossi Natalia Hanazaki Nivaldo Peroni 《Environment, Development and Sustainability》2000,2(3-4):177-193
Hot spots in Brazil include a variety of ecosystems, such as mangroves, forests, and the Brazilian savannah, locally called cerrado. Some of the rural populations in these hot spots are the caiçaras in SE Atlantic Forest coast, and the caboclos in the Amazon. In this study, we are concerned especially with the knowledge of caiçaras and caboclos, associated with practices that might have implications for management. Data were gathered through interviews with adults at the various communities studied, and through systematic observations, including samples of fishing trips and the mapping of fishing spots used in the Atlantic Forest coast. The use of resources from the surrounding vegetation includes collection of plants, cultivated fruit gardens, the swidden system, and a careful and managed extraction of fibres. Among animal resources, food taboos seem to be useful practices that might contribute to the maintenance of local natural resources. Potential management practices should be locally developed, such as the informal division of fishing spots in Atlantic Forest sites, and the maintenance of the diversity of cassava varieties in both the Atlantic Forest and Amazonian areas. 相似文献
252.
由于北方冬季气温较低,因冬季防冻及工艺需加装拌热装置,如果在污水处理系统中安装电拌热装置。不仅能有效的解决系统设备及管道的防冻问题,而且电拌热的运行成本较蒸汽拌热低、使用年限长,维护简单,有很好的使用及推广价值。 相似文献
253.
Farrukh Jamil Murni M. Ahmad Suzana Yusup Bawadi Abdullah 《International Journal of Green Energy》2016,13(4):424-429
Upgrading of bio-oil extracted from palm kernel shell (PKS) was performed using a lab-scale fixed-bed reactor with HZSM-5 as a catalyst. The catalytic cracking was carried out at optimized conditions: 0.3-MPa pressure, temperature of 500°C, and oil to catalyst ratio of 1:5. One of the challenges in upgrading bio-oil by catalytic cracking is deactivation of catalyst due to coke formation on catalyst surface. To overcome coke deposition, the upgrading process was carried out at 0.3-MPa pressure. Characterization of raw and upgraded bio-oil obtained through catalytic cracking was discussed in detail, indicating improvement in its physical properties. The distribution of products after cracking of bio-oil includes 58.89 wt% of organic liquid product, 15.63 wt% of aqueous fraction, 7.84 wt% of coke, and 17.64 wt% of gases. The degree of deoxygenation and calorific value of organic liquid product is 43.74% and 31.65 MJ/kg respectively. Organic liquid product obtained comprises 17.55% of hydrocarbons within the gasoline range. Hence, HZSM-5 proved its effectiveness for upgrading the bio-oil in a continuous mode. 相似文献
254.
A sample of 532 anhydrous ammonia nurse tanks with manufacture dates ranging from the 1950’s to 2011 were examined during 2012 by side angle ultrasound to measure the locations, sizes, and orientations of flaw indications. The indications were most frequently located on the head side of the head-to-shell welds and oriented perpendicular to the weld line in the welds’ heat affected zones. On average newer tanks had more indications than older tanks. Tanks that had been given a post-weld stress relief anneal had markedly fewer indications. 相似文献
255.
高强铝合金应力腐蚀开裂研究进展 总被引:1,自引:1,他引:0
综述了应力腐蚀理论的研究现状,其中氢致开裂理论和阳极溶解理论可较好解释高强铝合金的应力腐蚀开裂行为。结合应力腐蚀发生的三个必要条件,讨论了冶金因素、环境因素、应力因素对高强铝合金应力腐蚀敏感性的影响机制与作用结果。同时,介绍了国内外高强铝合金实验室模拟加速与自然环境应力腐蚀试验方法的研究进展、存在的不足及未来研究重点。 相似文献
256.
目的研究材料的应力腐蚀断裂时间。方法应用环境作用动力学理论,求解材料的应力腐蚀断裂时间函数。结果从环境作用动力学理论得到了材料的应力腐蚀断裂时间函数,并对AZ61和AZ80镁合金进行了试验验证。结论环境作用动力学理论可以描述镁合金材料应力腐蚀断裂时间;AZ61镁合金抗应力腐蚀性能优于AZ80镁合金。 相似文献
257.
为了探究二氧化碳致裂对贵州高瓦斯低渗透煤层的孔隙致裂增透作用,提出了应用低温氮吸附与FHH模型相结合的方法,分析致裂前后煤样的微观孔隙特征变化,并将分形维数与孔隙特征参数结合。研究结果表明:二氧化碳致裂对煤的孔隙具有明显的作用效果,致裂后煤岩体中微孔含量、比表面积减少,而孔容、平均孔直径增加;致裂作用会使煤的分形维数减小,孔隙表面受致裂效果会趋于光滑;受二氧化碳致裂作用,分形维数的大小与平均孔直径、孔容和吸附量等存在负相关关系,与比表面积、微孔含量等呈正相关关系。 相似文献
258.
259.
为探究基坑开挖导致邻侧既有盾构隧道出现开裂破损而带来的不利影响,采用地层-结构法与荷载-结构法相结合的计算方法,同时考虑内置钢筋对混凝土的加强作用,精细化地模拟基坑开挖影响下,非连续盾构管片结构接头处裂缝的扩展过程,揭示其开裂机制。研究结果表明:基坑开挖过程中,管片衬砌“横鸭蛋”变形模式决定了其开裂范围,即左、右拱腰附近为主开裂区;管片的裂损特征为纵向裂缝,初始裂缝由左、右拱腰外弧面逐渐向两侧接头处延展,右拱腰接头处裂缝扩展连接为沿厚度方向的环状裂缝。 相似文献
260.
温泉生态旅游是未来温泉旅游的发展方向。温泉生态旅游非常适合在温泉资源丰富而生态环境较脆弱的喀斯特地区开展。基于对贵州省息烽温泉资源开发利用现状的调查,对息烽温泉生态旅游的发展思路、开发模式和运行机制进行了初步研究,希望能为该区域发展温泉生态旅游提供决策参考。 相似文献