全文获取类型
收费全文 | 549篇 |
免费 | 25篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 7篇 |
综合类 | 40篇 |
化学工业 | 41篇 |
金属工艺 | 25篇 |
机械仪表 | 54篇 |
建筑科学 | 101篇 |
矿业工程 | 18篇 |
能源动力 | 31篇 |
轻工业 | 28篇 |
水利工程 | 5篇 |
石油天然气 | 15篇 |
武器工业 | 2篇 |
无线电 | 20篇 |
一般工业技术 | 36篇 |
冶金工业 | 60篇 |
原子能技术 | 6篇 |
自动化技术 | 89篇 |
出版年
2023年 | 8篇 |
2022年 | 14篇 |
2021年 | 19篇 |
2020年 | 10篇 |
2019年 | 6篇 |
2018年 | 5篇 |
2017年 | 16篇 |
2016年 | 22篇 |
2015年 | 21篇 |
2014年 | 42篇 |
2013年 | 31篇 |
2012年 | 43篇 |
2011年 | 57篇 |
2010年 | 33篇 |
2009年 | 35篇 |
2008年 | 27篇 |
2007年 | 28篇 |
2006年 | 29篇 |
2005年 | 23篇 |
2004年 | 14篇 |
2003年 | 10篇 |
2002年 | 15篇 |
2001年 | 8篇 |
2000年 | 10篇 |
1999年 | 8篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有578条查询结果,搜索用时 15 毫秒
1.
Moritz Raab Simon Maier Ralph-Uwe Dietrich 《International Journal of Hydrogen Energy》2021,46(21):11956-11968
A large-scale point to point hydrogen transport is one strategy for a prospective energy import scenario for certain countries. The case for a hydrogen transport from Australia to Japan has been addressed in several studies. However, most studies lack transparency and detailed insights into the made assumptions thus a fair evaluation of different transport pathways is challenging. To address this issue, we developed a model where a large-scale point to point hydrogen transport of liquid hydrogen is compared with the transport via liquid organic hydrogen carrier (LOHC), namely via methyl cyclohexane and hydrogenated dibenzyl toluene. We analyzed, where energy is required along the different pathways, where hydrogen losses do occur and how the costs are put together. Furthermore, the influence of hydrogen feed costs is also considered. For hydrogen production costs of 5 €2018/kgH2 the total delivery costs are in the range of 6.40– 8.10 €2018/kgH2. 相似文献
2.
包气带中不同示踪源层条件下核素迁移对比试验 总被引:2,自引:1,他引:1
为研究不同示踪源层材料对水份运移和核素迁移的影响,开展了以石英砂和黄土分别为示踪源层载体时Sr、Nd、Ce在包气带中迁移的对比试验。试验历时470d,在两种源层条件下各取土芯样4次。试验结果表明:在喷淋强度为5mm/h、3h/d条件下,Nd和Ce无论在石英砂示踪源层还是黄土示踪源层中浓度峰位均没有明显向下迁移;对于Sr,在黄土示踪源层中,470d后其峰位向下迁移约15cm(按质心计算为10cm左右),而从石英砂示踪源层中向下迁移不明显(按质心计算,迁移约2.7cm),只是峰位有些展宽。上述结果表明,极薄(7mm)的细石英砂层也能对非饱和入渗水产生明显屏流作用,使得核素从石英砂示踪源层中向下迁移速度减慢。 相似文献
3.
Comparative Study of Models on Confinement of Concrete Cylinders with Fiber-Reinforced Polymer Composites 总被引:4,自引:0,他引:4
The use of fiber-reinforced polymer (FRP) composites for strengthening and/or rehabilitation of concrete structures is gaining increasing popularity in the civil engineering community. One of the most attractive applications of FRP materials is their use as confining devices for concrete columns, which may result in remarkable increases of strength and ductility as indicated by numerous published experimental results. Despite a large research effort, a proper analytical tool to predict the behavior of FRP-confined concrete has not yet been established. Most of the available models are empirical in nature and have been calibrated against their own sets of experimental data. On the other hand, the experimental results available in the literature encompass a wide range of values of the significant variables. The objective of this work is a systematic assessment of the performance of the existing models on confinement of concrete columns with FRP materials. The study is conducted in the following steps: the experimental data on confinement of concrete cylinders with FRP available in the technical literature are classified according to the values of the significant variables; the existing empirical and analytical models are reviewed, pointing out their distinct features; the whole set of available experimental results is compared with the whole set of analytical models; and strengths and weaknesses of the various models are analyzed. Finally, a new equation is proposed to evaluate the axial strain at peak stress of FRP-confined concrete cylinders. 相似文献
4.
泌阳凹陷古城地区地震资料连片处理及认识 总被引:1,自引:1,他引:0
地震资料连片处理的目的是尽可能地克服不同年度、不同仪器、不同施工参数等造成的影响,同时消除不同的处理参数及处理流程所导致的差异。连片地震资料可以用于整体区域地震解释和地质认识。根据新老资料采集参数的特点,在静校正、叠前去噪、振幅补偿、叠前叠后提高分辨率等方面进行攻关,系统地解决了新老资料连片处理中的关键问题。通过处理资料的分析认为连片资料比较适合构造解释,而属性研究必须根据具体情况,一般是面元均化的网格与单块网格相比,网格差别大的,最好使用单块处理的资料,差别小的或者网格没有差别的,采用连片处理的资料进行研究。 相似文献
5.
本文基于新疆2001—2013年科学与实验研究投入数据的统计,并且对新疆与全国的科研经费、科研投入强度、科研产出等方面进行差异比较分析,发现新疆科研投入存在的不足和问题,最后在此基础上提出拓展经费融资渠道、加大政府科研投入力度、保护科研人员知识产权等相关政策建议。 相似文献
6.
Iosif Vranakis Anastasia Papadioti Yannis Tselentis Anna Psaroulaki Georgios Tsiotis 《Proteomics. Clinical applications》2013,7(1-2):193-204
Coxiella burnetii, the causative agent of Q fever, is an intracellular bacterium and a potential weapon for bioterrorism. The widespread throughout the world, zoonosis is manifested clinically as a self-limited febrile illness, as pneumonia (acute Q fever) or as a chronic illness with endocarditis being its major complication. The recent Netherlands Q fever outbreak has driven the bacterium from a relatively cryptic, underappreciated, “niche” microorganism on the sideline of bacteriology, to one of possibly great impact on public health. Advances in the study of this microorganism proceeded slowly, primarily due to the, until recently, obligatory intracellular nature of the pathogen that in its virulent phase I must be manipulated under biosafety level-3 conditions. Proteomic studies, in particular, have generated a vast amount of information concerning several aspects of the bacterium such as virulence factors, detection/diagnostic and immunogenic biomarkers, inter-/intraspecies variation, resistance to antibiotics, and secreted effector proteins with significant clinical impact. The phenomenon observed following the genomics era, that of generation and accumulation of huge amount of data that ultimately end up unexploited on several databases, begins to emerge in the proteomics field as well. This review will focus on the advances in the field of C. burnetii proteomics through MS, attempting in parallel to utilize some of the proteomics findings by suggesting future directions for the improvement of Q fever diagnosis and therapy. 相似文献
7.
Jing-Shan Zhao Jian-Yi WangFulei Chu Zhi-Jing FengJian S. Dai 《Mechanism and Machine Theory》2011,46(7):998-1015
This paper proposes a foldable stair that can be deployed for use and folded for conservation and investigates the geometry and statics of the structure. It not only has the moving flexibility of a mechanism but also has the high stiffness and high strength of statically indeterminate structures. The primary linkage is a deployable scissor-like element which forms the staircase after expanding. This paper starts with the analysis of the geometry of planar four- and six-bar mechanisms and processes to synthesize the foldable stair and then investigates its statics. The paper further investigates redundant inner forces of every link based on the second Castigliano theorem, develops a foldable stair model, assembles and manufactures. Working experiments verify the theoretical results and the outstanding advantages over the general fixed stairs. 相似文献
8.
通过非项目驱动与项目驱动的Java实验教学方法、教学过程及教学效果的对比分析,得出项目驱动式Java实验教学是培养学生的编程能力和编程兴趣、促进知识向能力的转化、培养高技能人才的有效途径。 相似文献
9.
The kinematics/statics and workspace of a 2(SP+SPR+SPU) serial–parallel manipulator are studied systematically. First, a 2(SP+SPR+SPU)
manipulator including an upper and a lower SP+SPR+SPU parallel manipulators is constructed, and the inverse/forward displacements,
velocity, acceleration and statics of the lower/upper parallel manipulators are studied, respectively. Second, the kinematics
and statics of the lower/upper manipulators are combined and the displacement, velocity, acceleration, statics, and workspace
of a 2(SP+SPR+SPU) manipulator are analyzed systematically. Third, the analytic solutions’ examples are given and verified
by the simulation mechanism. This manipulator has some potential applications for the robot’s arm, leg, and twist, the serial–parallel
machine tools, the sensor, the surgical manipulator, the tunnel borer, the barbette of warship, and the satellite surveillance
platform. 相似文献
10.