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991.
992.
隧道监控系统软件设计与实现 总被引:1,自引:0,他引:1
隧道监控系统软件开发平台主要分为组态与非组态两种,文中分析了两种平台各自的优缺点,提出采用组态与非组态组合开发的方案,并结合诸永高速公路东阳隧道群监控系统的开发对软件模块的设计和实现方法进行了详细阐述。 相似文献
993.
海底管线的地球物理探测技术探讨 总被引:1,自引:0,他引:1
从应用原理、工程实例、应用效果等方面分析了目前国内外常用的海底管线探测的技术方法,并且探讨了各种方法的优缺点及适用条件,总结了海底管线探测现状及发展趋势. 相似文献
994.
结合某跨海大桥桩基试验项目,对4组大直径PHC桩进行了竖向承载力静载试验,并通过桩身预埋的应变式钢筋计测试桩身轴力分布.试验结果表明,随着桩端土层刚度的提高,单桩极限承载力也将进一步增大,因此对于大直径PHC桩,也应选择较好土层作为持力层;随着桩顶荷载的不断增大,桩端阻力分担荷载所占的比例也逐渐增大,表明大直径PHC桩呈端承摩擦桩的承载性状;对于桩端持力层较好,而上覆软弱土层较厚的大直径PHC桩,尚应考虑上部土层侧摩阻力软化现象的影响;尽管大直径PHC桩桩身刚度较大,但在设计工作荷载下,此次试验的桩顶实测沉降主要由桩身压缩引起. 相似文献
995.
Jørgen Bendtsen Karin E. Gustafsson Johan Söderkvist Jørgen L.S. Hansen 《Journal of Marine Systems》2009,75(1-2):138-149
The transition zone between the North Sea and the Baltic Sea is a highly dynamic region where a general estuarine circulation forms a regional scale frontal system from northern Kattegat to the Arkona Sea. This system is characterized by an upper low saline out?owing Baltic water mass from the in?owing saline Skagerrak bottom water to the Kattegat and Belt Sea area. Large and rapid ?uctuations of the frontal system are caused by barotropic transports, forced by changing sea level difference between northern Kattegat and the western Baltic Sea, and this results in high variability of the hydrographic conditions and also in frequent in- and out?ow events to the Baltic. The dynamics in the region are here analyzed by a regional model of the transition zone, covering the area from the northern Kattegat to the Arkona Sea. The model is validated against water level, temperature and salinity measurements from the region, and the transports through the Danish straits are related to previous estimates and empirical relations. A sensitivity study quantify the role of bathymetry, the tidally induced mixing and the in?owing Skagerrak bottom water for ventilating the bottom water with Skagerrak water or surface water.Furthermore, the dynamics in the region is analyzed with tracers representing the age of the water. The distribution of age tracers with different boundary conditions are analyzed, and the role of advection and mixing for ventilating the bottom water is quanti?ed in terms of the water age. It is shown that the Great Belt area is a very dynamical area where bottom water is ventilated with surface water. The interannual variation of the ventilation of bottom water in the period 2001–2003 is analyzed by various age tracers and related to observed oxygen conditions, and it is shown that the extreme hypoxic event in the autumn 2002 in the southern Kattegat, the Great Belt and in the western Baltic Sea coincide with an unusual low vertical ventilation rate in the Great Belt area, but normal advection rates of bottom water from the northern Kattegat. This indicates that during this particular event, and probably in general, ventilation of bottom water in the Great Belt has signi?cant in?uence on oxygen conditions in the southern part of the region and for ventilation of bottom waters in the western Baltic Sea. In contrast, the central Kattegat is primarily ventilated by advection of bottom water from the Skagerrak. An age tracer representing the ventilation rate of bottom water with either Skagerrak water or surface water is shown to be inversely correlated to the observed oxygen distribution in the region. 相似文献
996.
The problem of filter-cake formation in highly permeable strata is urgently to be solved for slurry shield tunnelling. Adding coarse-particle materials in slurry is an effective method to solve the problem. A selfdesigned test device of slurry invasion and filter-cake formation in strata was adopted, and one kind of lightweight sand was selected as coarse particle materials. By changing the particle sizes of light-weight sand particles, the filtrate mass and the time of filter-cake formation under the condition of different additive contents and pressures were measured. And the influence of particle size of coarse-particle materials on filter-cake formation characteristics was analyzed. A triangular constriction calculation method was proposed, which can be used to quickly determine the influence range of coarse-particle materials on the pore size variation of the strata. The test results show that: (1) the addition of coarse-particle materials can significantly reduce the inter-particle pore size and effectively improve the clogging effectiveness under the condition of this tested strata. (2) The particle size of coarse-particle materials has a great influence on filter-cake formation characteristics. The coarse-particle material with smaller particle size has a better clogging effect, and its filter-cake formation characteristics are more stable. The coarse-particle material with larger particle size has a higher volatility in its filter-cake formation characteristics. (3) Coarse-particle materials with different particle sizes result in different final filter-cake structures. When the coarse-particle materials possess a larger particle size, a mixed filtercake structure is formed, and when the particle size is small, a double-layer filter-cake structure is formed. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献
997.
Sun L.Huang Y.Wang Q.Zhou H.Dai C. 《现代隧道技术》2018,(5):140-145
Based on the background of the first phase project of the R3 line of Jinan Rail Transit, and in view of the metro shield tunnel passing under the existing railway bridge and subgrade, this paper uses Abaqus to establish a numerical model to simulate the deformation of the existing bridge and subgrade of the Jiaoji railway line under the two conditions of non-active reinforcement and reinforcement. The results show that under the condition of no reinforcement, the maximum settlement of the top bridge on the pier is -5.88 mm, and the maximum settlement difference is 5.16 mm, which exceed the deformation control requirements of the 5 mm regarding the bridge pier of the railway with ballast track. The maximum lateral displacement and longitudinal displacement of the pier are 0.28 mm and -3.01 mm, respectively. After the reinforcement measures of the bored piles are adopted, the maximum settlement of the top bridge on the pier is -1.71 mm, and the maximum settlement difference is 1.16 mm, which fully meet the bridge pier deformation control standard. The maximum lateral displacement and longitudinal maximum displacement are -0.245 mm and -2.83 mm, respectively, which meet the requirements of the control standard. The vertical settlement of the railway subgrade is relatively small. The maximum settlement values under the two working conditions are -12.31 mm and -11.97 mm, respectively, which meet the subgrade settlement control requirement of 20 mm. It is proved that the reinforcement effect of the bored pile is good, and the reinforcement scheme is safe and feasible. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献
998.
Rachel Gjelsvik Tiller Åshild Løvås Borgersen Øyvind Knutsen Jennifer Bailey Hans Vanhauwaert Bjelland Jarle Mork 《Coastal management》2017,45(1):1-23
Over the last decades, a dense population of the deep-sea/oceanic scyphozoan jellyfish Periphylla periphylla has established itself as top predator in the Trondheimsfjord in Norway, which has caused the traditional fisheries in this fjord to suffer. This was, however, not the first fjord this jellyfish invaded, and data suggest that it will not be the last one, either. With warmer temperatures, the jellyfish is moving northward in Norway, but not all fjords are created equal, and it is not thriving or taking up residence just anywhere. The current article explores three fjords in which Periphylla periphylla has become the top predator and outcompeted former ones. The main question of interest is why the jellyfish becomes dominant in one fjord and not another. The next question is which other Norwegian fjords further north exist with similar characteristics where we therefore would expect Periphylla periphylla to proliferate in the future. The latter is important from a policy and adaptation perspective for the local community of people, since the proliferation of the species unmistakably leads to fewer fish for commercial harvest and potentially less attractive waters for tourism purposes. Results show that three northern fjords, the Skjerstadfjorden the Holandsfjorden, and Stordjupna in the Vestfjord appear to be particularly vulnerable to a future Periphylla periphylla invasion. 相似文献
999.
Dimitrios Dalaklis Megan L. Drewniak Jens-Uwe Schröder-Hinrichs 《WMU Journal of Maritime Affairs》2018,17(2):129-147
A rather significant number of business entities already operate within (or, have considered to exploit) the Arctic region, focusing upon previously untapped resources such as precious minerals and large quantities of oil and gas; touristic and fishing activities are clearly on the rise, with various endeavors of maritime transport also being put forward. Up until recently, harsh year-long environmental conditions have significantly hindered the necessary access and transport connections in the Arctic. Even in the case that weather conditions did permit vessels’ passage, unreliable navigational aids and lack of infrastructure/support provided obstacles difficult to overcome. However, environmental data recorded during the last couple of decades clearly indicates that there is a continuous decline of ice coverage in the “High North.” Given this steady decline, the Arctic has now been viewed as a promising field for economic activities and is considered as a potential connecting corridor between Asia and Europe/America (and vice-versa). As human presence and operations are expected to intensify there, it is of utmost importance to evaluate the current level of support towards ships that will be crossing the region; capabilities in relation to search and rescue (SAR) operations and oil spill response are also important. The analysis in hand will first deliver a discussion of the so-called Arctic Passages. While various different maritime routes have been proposed in relation to the Arctic, the most promising one, the Northern Sea Route (NSR), will provide the epicenter of discussion. Through an extensive literature review that includes numerous internet resources, the current analysis will identify the numbers of icebreakers already operating in the NSR, as well as those that will be commissioned into service in the near future. The choice to research the specific type of vessels is supported by a simple argument: icebreakers currently are and will continue to be in the foreseeable future the main “tool” to support shipping activities in the Arctic. Furthermore, emergency management capabilities in the Russian Arctic will be examined to include the current state of rescue coordination centres along with the availability of SAR assets. Additionally, the efforts thus far by the Arctic Council to increase coordination and interaction among the States involved in Arctic affairs will be summarized; the latter will be achieved via a brief review of a very important legally binding agreement: the “search and rescue” instrument. In conclusion, the Russian State has already heavily invested in icebreakers’ building and their current number is fully capable to handle the present level of limited traffic. On the other hand, ships are currently faced with long distances to cross (often without adequate support) adverse environmental conditions, unpredictable hurdles, and slow response times in case of an emergency. Therefore, in case ships operating in the region are increased, it will be difficult to deal with all the additional demands for support. Of particular interest is the fact that considering the vast area of the NSR, the overall available response capabilities in the region under discussion are rather thin; any further increase of maritime traffic in the “High North” must be balanced with additional strengthening of emergency management capabilities. In any case, should the NSR become fully integrated in the global maritime transport system, Russia’s geopolitical status will be clearly improved and further research is needed to discuss the implications both at the regional and global levels. 相似文献
1000.
Traditional travel behavior theory regards travel time as a waste. Recent studies suggest that it carries a positive utility, among other reasons for the benefit of the activities conducted while traveling. However, most studies of travel time use have focused on conventional trains in developed countries. Few have systematically examined the permeation of information and communication technology (ICT) into travel time use and the correlates of activity participation in developing countries, particularly on high speed rail (HSR). Using a survey conducted on the Shanghai–Nanjing corridor (N = 901), this study examines how HSR passengers use their travel time and explores the correlates of the different types of activities of business and non-business travelers, respectively, through multivariate probit models. We found that 96% of the respondents use ICT during their HSR journey and that most passengers spend some of their travel time on work-related activities. Moreover, items carried and advance planning as well as work-related travel attributes contribute significantly to activity participation. However, the factors affecting time use of business and non-business travelers differ. HSR service design should facilitate passenger engagement in various activities and improvement of their travel experience. A stable internet connection, adequate power sockets, and a noise-free environment will promote both work and leisure activities on the HSR. 相似文献