全文获取类型
收费全文 | 7652篇 |
免费 | 1079篇 |
国内免费 | 797篇 |
专业分类
电工技术 | 139篇 |
技术理论 | 1篇 |
综合类 | 529篇 |
化学工业 | 1087篇 |
金属工艺 | 55篇 |
机械仪表 | 105篇 |
建筑科学 | 314篇 |
矿业工程 | 247篇 |
能源动力 | 208篇 |
轻工业 | 369篇 |
水利工程 | 139篇 |
石油天然气 | 5490篇 |
武器工业 | 22篇 |
无线电 | 211篇 |
一般工业技术 | 322篇 |
冶金工业 | 92篇 |
原子能技术 | 32篇 |
自动化技术 | 166篇 |
出版年
2024年 | 18篇 |
2023年 | 106篇 |
2022年 | 269篇 |
2021年 | 297篇 |
2020年 | 275篇 |
2019年 | 257篇 |
2018年 | 240篇 |
2017年 | 237篇 |
2016年 | 312篇 |
2015年 | 287篇 |
2014年 | 413篇 |
2013年 | 494篇 |
2012年 | 550篇 |
2011年 | 630篇 |
2010年 | 484篇 |
2009年 | 426篇 |
2008年 | 406篇 |
2007年 | 509篇 |
2006年 | 523篇 |
2005年 | 418篇 |
2004年 | 411篇 |
2003年 | 372篇 |
2002年 | 288篇 |
2001年 | 212篇 |
2000年 | 232篇 |
1999年 | 157篇 |
1998年 | 126篇 |
1997年 | 116篇 |
1996年 | 104篇 |
1995年 | 87篇 |
1994年 | 66篇 |
1993年 | 37篇 |
1992年 | 31篇 |
1991年 | 28篇 |
1990年 | 31篇 |
1989年 | 20篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1973年 | 1篇 |
1959年 | 1篇 |
1951年 | 3篇 |
排序方式: 共有9528条查询结果,搜索用时 15 毫秒
1.
2.
《International Journal of Hydrogen Energy》2022,47(6):3906-3917
The current trends in energy were described, the main of which is the use of alternative energy sources, especially hydrogen. The most common methods of hydrogen accumulation were proposed: accumulation of compressed gaseous hydrogen in high-pressure tanks; accumulation of liquid hydrogen in cryogenic tanks; storing hydrogen in a chemically bound state; accumulation of gaseous hydrogen in carriers with a high specific surface area. Based on the combination of advantages and disadvantages, the most promising methods of accumulation were selected: storage of liquid hydrogen and storage of hydrogen in carriers with a high specific surface area. The main requirement for materials for hydrogen storage by these methods was revealed – a high specific surface area. Prospects for the development of waste-free low-emission technologies due to the recycling of secondary raw materials and the development of low-temperature technologies for the synthesis of functional and structural materials were substantiated. The applicability of large-scale ash and slag waste from coal-fired thermal power plants as a raw material for obtaining materials by low-temperature technologies was shown. The traditional ways of using ash and slag waste as a raw material, active additive and filler in the production of cements were described. Modern technologies for the production of innovative materials with a unique set of properties were presented, namely carbon nanotubes, silica aerogel and geopolymer materials. The prospect of using geopolymer matrices as a precursor for the synthesis of a number of materials was described; the most promising type of materials was selected – geopolymer foams, which are mainly used as sorbents for purifying liquids and gases or accumulating target products, as well as heat-insulating materials. The possibility of obtaining products of any shape and size on the basis of geopolymer matrices without high-temperature processing was shown. The special efficiency of the development of the technology of porous granules and powders obtained from a geopolymer precursor using various methods was substantiated. The obtained granules can be used in the following hydrogen storage technologies: direct accumulation of hydrogen in porous granules; creation of insulating layers for liquid hydrogen storage units. 相似文献
3.
4.
5.
Temperature history can have a significant effect on the strength of water-saturated chalk.In this study,hydrostatic stress cycles are applied to understand the mechanical response of chalk samples exposed to temperature cycling between each stress cycle,compared to the samples tested at a constant temperature.The total accumulated strain during a stress cycle and the irreversible strain are reported.Chalk samples from Kansas(USA)and Mons(Belgium),with different degrees of induration(i.e.amount of contact cementation),were used.The samples were saturated with equilibrated water(polar)and nonpolar Isopar H oil to quantify water weakening.All samples tested during 10 stress cycles with varying temperature(i.e.temperature cycled in between each stress cycle)accumulated more strain than those tested at constant temperatures.All the stress cycles were performed at 30℃.The two chalk types behaved similarly when saturated with Isopar H oil,but differently when saturated with water.When saturated with water,the stronger Kansas chalk accumulated more total strain and more irreversible strain within each stress cycle than the weaker Mons chalk. 相似文献
6.
7.
The NW‐SE trending Cantarell structure in the Gulf of Campeche hosts the largest oilfield in Mexico. The oil occurs predominantly in latest Cretaceous – earliest Tertiary breccias with subsidiary reserves in Upper Jurassic (Oxfordian and Kimmeridgian) and Lower Cretaceous oolitic and partially dolomitized limestones, dolomites and shaly limestones. Cantarell has been interpreted both as a fold‐and‐thrust zone and as a dextral transpressional structure. Analysis of structure contours at 100m intervals, on the tops of the Tertiary breccia and the Kimmeridgian (Upper Jurassic) dolomite, indicates that the structure is an upright cylindrical fold with gently plunging conical terminations; there is also a conical portion in the central part of the structure. The axes of the central, NW and SE cones are subvertical. This geometry indicates that the two fold terminations and the central cone are aprons rather than points, with the NW and central cone axes intersecting the cylindrical fold axis at the point where the geometry switches from conical to cylindrical. The apical angle (i.e. the angle between the fold and cone axes) varies as follows: (i) in the NW cone, it is ~70° in the breccia and ~76° in the Kimmeridgian dolomite; (ii) in the central cone, it is ~77° in the breccia and ~73° in the Kimmeridgian dolomite; and (iii) in the SE cone, it is ~64° in the breccia and ~57° in the Kimmeridgian dolomite. This indicates that whereas the fold opens with depth in the NW cone, it tightens with depth in the central and SE cones. Assuming a parallel fold geometry, these apical angles indicate an increase in volume in the NW cone (i.e. larger hydrocarbon reservoirs), compared to the central and SE cones. Theoretical considerations indicate that the curvature increases dramatically towards the point of the cone. In the case of the Cantarell structure, the apices of the cones are located at the conical‐cylindrical fold junctions, where the highest curvature may have resulted in a higher degree of fracturing. The coincidence of maximum curvature and the intersection of the conical and cylindrical fold axes in the fold culminations with porous and permeable reservoir rocks may have made these locations favourable for the accumulation of hydrocarbons. 相似文献
8.
9.
大庆长垣以东地区深层天然气输导通道主要由断裂、不整合面和砂体构成。该区砂体横向分布不稳定,物性差,不是天然气侧向长距离运移的输导通道,但可以起到衔接输导作用。输导通道时该区天然气成藏与分布起到了重要控制作用,主要表现在断裂将天然气输导致上覆不同储集层中聚集成藏。不整合面和砂体将天然气输导到四周古隆起上聚集成藏。沿断裂输导的天然气形成以断层为主的构造气藏。沿不整合面和砂体输导的天然气形成以地层及岩性为主的气藏。沿断裂输导运移聚集的天然气在剖面上呈串多层分布,沿不整合面和砂体输导运移聚集的天然气在平面上呈环状分布。 相似文献
10.
同沉积压扭断层在柴达木盆地西部南区油气成藏中的意义 总被引:2,自引:1,他引:1
柴达木盆地西部南区逆断层断面产状呈上陡下缓的铲式特征,生长系数变化在1.3~2.5之间,断距纵向上向浅层逐渐变小和横向上向一个方向逐渐增大,总体表现为典型的同沉积压扭断层。指出该断层演化主要经历了同生冲断期、褶皱发育期、平静期及二次活动期4个阶段,长期活动的NWW向主干断层除控制构造带的展布格局外,还控制着烃源岩、储集层、盖层及其组合的空间发育,同时还有效地沟通着源岩与圈闭并成为有效输导体系的一部分,近N S向展布的次级断层决定着局部构造的发育特点,与NWW向断层联合控制着油气的局部富集。 相似文献