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The main obstacles to boosting the bicycle as a mode of transport are safety concerns due to interactions with motorized traffic. One option is to separate cyclists from motorists through exclusive bicycle priority lanes. This practice is easily implemented in uncongested traffic. Enforcing bicycle lanes on congested roads may degenerate the network, making the idea very hard to sell both to the public and the traffic authorities. Inspired by Braess Paradox, we take an unorthodox approach to seeking latent misutilized capacity in the congested networks to be dedicated to exclusive bicycle lanes. The aim of this study is to tailor an efficient and practical method to large size urban networks. Hence, this paper appeals to policy makers in their quest to scientifically convince stakeholder that bicycle is not a secondary mode, rather, it can be greatly accommodated along with other modes even in the heart of the congested cities. In conjunction with the bicycle lane priority, other policy measures such as shared bicycle scheme, electric-bike, integration of public transport and bicycle are also discussed in this article. As for the mathematical methodology, we articulated it as a discrete bilevel mathematical programing. In order to handle the real networks, we developed a phased methodology based on Branch-and-Bound (as a solution algorithm), structured in a less intensive RAM manner. The methodology was tested on real size network of city of Winnipeg, Canada, for which the total of 30 road segments – equivalent to 2.77 km bicycle lanes – in the CBD were found. 相似文献
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Mario Hoppema Eberhard Fahrbach Michel H. C. Stoll Hein J. W. de Baar 《Journal of Marine Systems》1999,19(4):1935
Data from two cruises, one in April/May 1996 and one in December/January 1993, covering the same wide area in the offshore Weddell Sea, were used to derive the annual extent of entrainment and the capacity of the biological pump. The former property was obtained with the help of dissolved oxygen data, whereas the latter was approximated with nutrients. Especially the data from April/May, representing the initial state of the winter surface layer, were crucial to assess the annual extent of these processes. The results were applied to our carbon dioxide data. The annual increase of the Total CO2 (TCO2) concentration in the surface layer due to vertical transport amounts to 16.3 μmol kg−1. An entrainment rate of deep water in the surface layer amounting to 35±10 m yr−1 was deduced. The compensating, biologically mediated TCO2 reduction was calculated to be larger than the TCO2 increase due to vertical transport. Since the balance of these two processes determines whether the Weddell Sea is a source or a sink of CO2, this indicates that the Weddell Sea, albeit upwelling area, is definitely a sink for atmospheric CO2 on an annual basis. This conclusion is further supported by contemplations that the biological drawdown of CO2 in the Weddell Sea as a whole is probably underestimated by our calculations. The new production for the Weddell Sea on a per unit area basis was found to be much higher than that for the Antarctic Ocean, when the latter value is being obtained by traditional biological methods. On the other hand, the CO2 uptake by the Weddell Sea on a per unit area basis is somewhat smaller than the CO2 uptake by the world ocean. 相似文献
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用新试制的21—2N钢和国产21—4N钢进行了CHRYSLER(CA488)引进发动机排气门生产国产化试验。试验结果表明,CA488发动机排气门生产国产化是可行的,新试制的21—2N钢冷热加工性能优于21—4N钢。对新试制的21—2N钢进行了50~250MPa应力范围和700~850℃温度范围的高温持久拉伸试验,与21—4N钢数据比较结果表明,两种钢的高温持久强度基本接近。 相似文献
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公路排水系统设计参数研究 总被引:22,自引:1,他引:22
为了解决非单一纵坡条件下沟渠设计纵坡的确定问题,提出了沟渠名义设计纵坡的概念,给出了相应的计算公式。根据各类沟渠的结构重要性、损坏后果、修复可易性、使用要求以及国外的相关规定,提出了路界表面排水设施的设计降雨重现期和安全高度建议值。此外,讨论了沟管冲淤条件和允许最小纵坡的关系,对现行公路排水设计规范中的相应规定提出了修改建议。该成果可用于公路排水设计,也可为以后的规范修订提供技术支持。 相似文献
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机械加工乳化液净化再生治理工艺参数的研究 总被引:4,自引:0,他引:4
对乳化液经过充氧、二级垂直磁化、吸附过滤净化工艺过程进行了研究,延长其使用寿命为原来的4倍以上,节省大量乳化液,减少排污量;废乳化液电凝聚处理最佳条件:极板间距10mm、电流密度5mA/cm^3、凝聚时间30min等,处理后出水:COD760mg/L、NO2^-180mg/L、pH9.2,可以用来循环配制乳化液,性能符合GB6144~85标准要求;优化出化学混凝处理废乳化液的最佳混凝剂为PAC PAM及酸性A1C13废液,操作条件为pH=6.0~7.5,投量PAC:2g/L、PAM:20mg/I。;酸性A1C13废液:18ml/L,出水不能用来配制乳化液;混凝絮渣经浓盐酸处理:每升乳化废液混凝产生的絮渣需12mL浓盐酸,油被溶出约16mL/L,余下的混合液可用来循环处理废乳化液;实现以废治废、出水循环使用、清洁生产的目的. 相似文献
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为解决水位变动较大河道的环保疏浚与底泥处置问题,基于山美水库进库河道段疏浚工程,总结如何合理地选择疏浚时机,采用适合特定水位下的疏浚设备统筹施工,利用太阳能自然干化降低底泥含水率,从而提高生产效率、节约成本,为后续工程提供经验借鉴。 相似文献
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