全文获取类型
收费全文 | 744篇 |
免费 | 75篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 25篇 |
综合类 | 51篇 |
化学工业 | 96篇 |
金属工艺 | 116篇 |
机械仪表 | 24篇 |
建筑科学 | 147篇 |
矿业工程 | 8篇 |
能源动力 | 29篇 |
轻工业 | 31篇 |
水利工程 | 5篇 |
石油天然气 | 2篇 |
武器工业 | 2篇 |
无线电 | 33篇 |
一般工业技术 | 156篇 |
冶金工业 | 76篇 |
原子能技术 | 1篇 |
自动化技术 | 28篇 |
出版年
2024年 | 3篇 |
2023年 | 9篇 |
2022年 | 15篇 |
2021年 | 12篇 |
2020年 | 23篇 |
2019年 | 16篇 |
2018年 | 32篇 |
2017年 | 24篇 |
2016年 | 33篇 |
2015年 | 27篇 |
2014年 | 37篇 |
2013年 | 40篇 |
2012年 | 49篇 |
2011年 | 57篇 |
2010年 | 57篇 |
2009年 | 40篇 |
2008年 | 45篇 |
2007年 | 57篇 |
2006年 | 50篇 |
2005年 | 37篇 |
2004年 | 41篇 |
2003年 | 28篇 |
2002年 | 20篇 |
2001年 | 14篇 |
2000年 | 9篇 |
1999年 | 9篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1984年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有830条查询结果,搜索用时 15 毫秒
61.
生产汽车蒙皮用铝合金板材的先进工艺 总被引:3,自引:1,他引:2
马道章 《有色金属材料与工程》2001,22(2):80-82
本文推荐了一种适于生产汽车蒙皮用铝合金板材的先进工艺-基于哈兹列特工艺的连续轧工艺。该工艺素以高产量、低成本及合金品种宽著称,唯铸板表面质量欠佳,但经过一系列工艺改进,板材的表面质量已能满足汽车蒙皮的要求,并在美国已被采用于项目建设。这是一种意义重大的突破,值得汽车制造业和铝加工业的重视。 相似文献
62.
广州白云国际会议中心景观桥采用缩口钢承板作为组合桥面结构板,这在桥梁建造上是较罕见的。本文介绍了缩口钢承板在桥梁使用上的特点、安装过程,开创了材料使用新思路,为桥梁工程提供了经验。 相似文献
63.
《International Journal of Hydrogen Energy》2022,47(2):984-992
The rational design and preparation of bifunctional electrocatalysts with pleasant oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performance is crucial for extensive commercial applications of rechargeable Zn–air batteries (ZABs). Herein, we report a simple method to obtain multi-metal (Fe, Ni, Zn) embedded in N-doped carbon sheets entangled with carbon nanotubes (CNTs) as superior oxygen electrocatalysts (FeNi-NCS-2). The resultant FeNi-NCS-2 exhibits an impressive electrochemical performance, providing a reversible oxygen overpotential as low as 0.758 V. The ZAB with FeNi-NCS-2 as the air cathode shows a promising capacity of 639.71 mAh g?1 at 20 mA cm?2, a power density of 109.8 mW cm?2 and cycling stability of over 130 cycles at 10 mA cm?2 with an energy efficiency of about 55%, superior to the ZAB based on Pt/C–IrO2. The satisfactory electrocatalytic performance is mainly due to the Fe, Ni-based nanoparticles protected by graphitic carbon layers, hierarchical porous lamellar structures that promote the accessibility between the active centers and the electrolyte as well as self-growing tangled carbon nanotubes that provide fast transmission channels. This study presents a facile way for the synthesis of highly efficient ORR/OER bifunctional electrocatalysts for high-performance rechargeable ZABs. 相似文献
64.
《International Journal of Hydrogen Energy》2022,47(9):6282-6294
Methanol steam reforming has been used for in-situ hydrogen production and supply for proton exchange membrane fuel cell (PEMFC), while its power density and energy efficiency still needs to be improved. Herein, we present a novel methanol steam reforming microreactor based on the stacked wave sheets and copper foam for highly efficient hydrogen production. The structural of stacked wave sheets and copper foam, and their roles in the microreactor are described, methanol catalytic combustion is adopted to supply heat for methanol steam reforming reaction and enables the microreactor to work automatically. For catalyst carrier, a fractal body-centered cubic model is established to study the flow characteristics and chemical reaction performances of the copper foam with coated catalyst layer. Both simulation and experimental results showed that the reformate flowrate increases with the increasing of microreactor layers and methanol solution flowrate, the discrepancies of methanol conversion between simulation and experimental tests are less than 7%. Experimental results demonstrated that the reformate flowrate of 1.0 SLM can be achieved with methanol conversion rate of 65%, the output power of the microreactor is 159 W and power density is 395 W/L. The results obtained in this study indicates that stacked wave sheets and copper foam can uniform the reactant flow and improve the hydrogen production performances. 相似文献
65.
66.
67.
This work addresses the problem of finding a substitute material model for describing the load response of globally flat corrugated sheets made from multidirectional laminates. Exact solutions of the equations governing thin singly curved shells give the displacements, strains and stresses within a unit cell extending over one period of the corrugation pattern. The forces reacting to enforced unit deformations determine the constitutive law of the substitute material model. The analytical results are compared with those of finite-element models. 相似文献
68.
The effect of specimen thickness on the experimental and finite element characterization of CTOD in extra deep drawn steel sheets 总被引:1,自引:0,他引:1
Recent experimental results by us have indicated that the load-drop technique can serve as a valid fracture criterion for
predicting elastic-plastic fracture in extra deep drawn (EDD) steel sheets or in predominantly plane stress conditions. The
purpose of this investigation is to examine the validity of aJ-integral as a fracture parameter and theJ-CTOD relation for the determination of critical CTOD in predominantly plane stress fracture (CTOD-crack tip opening displacement).
Fracture tests were performed and experimental results were generated on fracture behaviour of EDD (0·06%C) steel sheets with
CT specimens and using ‘load-drop’ as a fracture criterion. Critical CTOD was determined by using theJ-CTOD relation in addition to several existing techniques. A full 3-D finite element model was formulated to verify the critical
load, critical CTOD and plastic-zone size. The critical CTOD was shown to increase with increasing specimen thickness and
appeared to be approaching a higher limiting value. The characteristic features of predominantly plane stress fracture or
general yielding fracture mechanics are summarized in conclusion 相似文献
69.
Wenshu Chen Jiajun Gu Yongping Du Fang Song Fanxing Bu Jinghan Li Yang Yuan Ruichun Luo Qinglei Liu Di Zhang 《Advanced functional materials》2020,30(25)
Large‐scale production of hydrogen from water‐alkali electrolyzers is impeded by the sluggish kinetics of hydrogen evolution reaction (HER) electrocatalysts. The hybridization of an acid‐active HER catalyst with a cocatalyst at the nanoscale helps boost HER kinetics in alkaline media. Here, it is demonstrated that 1T–MoS2 nanosheet edges (instead of basal planes) decorated by metal hydroxides form highly active / heterostructures, which significantly enhance HER performance in alkaline media. Featured with rich / sites, the fabricated 1T–MoS2 QS/Ni(OH)2 hybrid (quantum sized 1T–MoS2 sheets decorated with Ni(OH)2 via interface engineering) only requires overpotentials of 57 and 112 mV to drive HER current densities of 10 and 100 mA cm?2, respectively, and has a low Tafel slope of 30 mV dec?1 in 1 m KOH. So far, this is the best performance for MoS2‐based electrocatalysts and the 1T–MoS2 QS/Ni(OH)2 hybrid is among the best‐performing non‐Pt alkaline HER electrocatalysts known. The HER process is durable for 100 h at current densities up to 500 mA cm?2. This work not only provides an active, cost‐effective, and robust alkaline HER electrocatalyst, but also demonstrates a design strategy for preparing high‐performance catalysts based on edge‐rich 2D quantum sheets for other catalytic reactions. 相似文献
70.