全文获取类型
收费全文 | 50860篇 |
免费 | 5830篇 |
国内免费 | 3582篇 |
专业分类
电工技术 | 3846篇 |
技术理论 | 9篇 |
综合类 | 3514篇 |
化学工业 | 8569篇 |
金属工艺 | 3449篇 |
机械仪表 | 2516篇 |
建筑科学 | 3292篇 |
矿业工程 | 1361篇 |
能源动力 | 1592篇 |
轻工业 | 1762篇 |
水利工程 | 475篇 |
石油天然气 | 543篇 |
武器工业 | 638篇 |
无线电 | 6189篇 |
一般工业技术 | 14375篇 |
冶金工业 | 2296篇 |
原子能技术 | 361篇 |
自动化技术 | 5485篇 |
出版年
2024年 | 308篇 |
2023年 | 1227篇 |
2022年 | 1587篇 |
2021年 | 2182篇 |
2020年 | 2386篇 |
2019年 | 1782篇 |
2018年 | 1625篇 |
2017年 | 1801篇 |
2016年 | 1771篇 |
2015年 | 1850篇 |
2014年 | 3047篇 |
2013年 | 2944篇 |
2012年 | 3562篇 |
2011年 | 4152篇 |
2010年 | 3016篇 |
2009年 | 3081篇 |
2008年 | 2907篇 |
2007年 | 3418篇 |
2006年 | 2882篇 |
2005年 | 2739篇 |
2004年 | 2192篇 |
2003年 | 1951篇 |
2002年 | 1592篇 |
2001年 | 1259篇 |
2000年 | 1071篇 |
1999年 | 761篇 |
1998年 | 647篇 |
1997年 | 477篇 |
1996年 | 372篇 |
1995年 | 305篇 |
1994年 | 295篇 |
1993年 | 224篇 |
1992年 | 163篇 |
1991年 | 163篇 |
1990年 | 141篇 |
1989年 | 109篇 |
1988年 | 51篇 |
1987年 | 37篇 |
1986年 | 34篇 |
1985年 | 25篇 |
1984年 | 36篇 |
1983年 | 19篇 |
1982年 | 29篇 |
1981年 | 9篇 |
1980年 | 14篇 |
1979年 | 3篇 |
1976年 | 3篇 |
1963年 | 2篇 |
1955年 | 4篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
81.
82.
Magnesiumandmagnesiumalloyshavebeenin vestigatedashydrogenstoragematerialsforseveralde cadesbecausefarmorehydrogenbyweightcanbestoredinthemthaninmostoftheothercurrentlyknownhydrogenstoragealloys .Moreover ,thehighnaturalabundanceofMg ,itslightmassandenviron mentalcompatibilitypotentiallymakemagnesiumoneofthemostprospectivecandidatesforfuturehydrogenstoragematerials .Unfortunately ,thepracticalappli cationofMganditsalloyshasbeenlimitedonlytocertainstoragedevicebecauseoftheirpoorhydriding dehydr… 相似文献
83.
84.
Y.X. Li 《Materials Letters》2007,61(22):4366-4369
TiC/Al composite was successfully synthesized utilizing laser ignited self-propagating high-temperature synthesis (SHS) of Al-C-Ti system with the different C/Ti molar ratio. When the molar ratio of C to Ti is below 1:1 in the starting materials, in addition to fine TiC particulates, a large amount of Al3Ti phase was found in the composites; however, when the molar ratio of C to Ti is 1:1 in the starting materials, the Al3Ti phase was almost completely eliminated and the distribution of TiC particulates generally appeared to be more homogeneous throughout the products synthesized. 相似文献
85.
超支化聚合物,具有多端基的“缺陷核壳”空间结构,化学反应性活泼,易于改性,与相应的线型聚合物相比,拥有特殊的性能,在多领域展现出广阔的应用前景。随着合成技术的进步,它们的应用研究,尤其是功能化的应用研究,成为多年来的研究热点。主要介绍超支化聚合物的结构、性能、合成及其功能化应用研究概况。 相似文献
86.
87.
Study on Adsorption Behavior of Rare Earth Complexes on Nanometer-Size Titanium Dioxide with ICP-AES
Inrecentyears ,rareearthelements (REEs)havebeenwidelyusedinfunctionalmaterials ,cata lystsandotherproductsinindustry ,diagnosisreagentsofmagneticresonanceimaging (MRI)inmedicineandsomefertilizersinagricultureespeciallyinChina .However,asaresultoftheirusage ,moreandmoreREEsaregettingintotheenvironment,andalsointohumanbodyviafoodchain[1,2 ] .Itisnotclearwhetherrareearthelementsareessentialforman ,soitisveryurgenttostudythebiologicaleffectofrareearthelementsinhumanhealthandenvironment .Inthes… 相似文献
88.
Crystalline Behavior and Magnetic Properties of Nd60Fe30-x Al10Cox(x = 0,5,10) Bulk Amorphous Alloys
Crystalline behavior and magnetic properties of Nd60Fe30-xAl10Cox( x = 0, 5, 10) bulk amorphous alloys were investigated by differential scanning calorimeter (DSC), X-ray diffraction (XRD) and the vibrating sample magnetometer (VSM). Neither glass transition nor supercooled liquid region before crystallization was observed for the as-cast Nd60Fe30-xAl10Cox ( x = 0,5,10) bulk amorphous alloys. The glass forming ability can be improved significantly by the addition of Co. The as-cast Nd60Fe30-xAl10Cox (x = 0,5,10) alloys show hard magnetic behavior. With the addition of Co content, intrinsic coercivity (iHc) increases while the saturation magnetization(σs) and remanence (σr) decrease. The Curie temperature for the as-cast Nd60Fe30-xAl10Cox alloys increases from 451 K for x =0 to 468 K for x = 10. Some pre-cipitation of crystalline phases does not affect the hard magnetic properties of Nd60Fe30-xAl10Cox(x = 0,5,10) alloys, while the hard magnetic behavior disappears quickly after the alloys being completely crystallized. 相似文献
89.
Influence of Ni Interlayers on the Mechanical Properties of Ti6Al4V/(WC-Co) Friction Welds 总被引:2,自引:0,他引:2
M. Shamanian M. Salehi A. Saatchi T. H. North 《Materials and Manufacturing Processes》2003,18(4):581-598
Ni interlayers were introduced prior to dissimilar friction welding of Ti6Al4V base material to three cemented carbide substrates. The fracture strength of Ti6Al4V/(WC-6 wt% Co) welds were poor and were markedly improved when 20-µm thick Ni interlayers were introduced prior to dissimilar friction welding. These results were only produced when the (WC-6 wt% Co) cermet was electroplated prior to friction welding. When the Ti6Al4V alloy was electroplated prior to friction welding, fractured WC particles and cracking were observed in the (WC-Co) carbide substrate. The fracture strengths of Ti6Al4V/(WC-11 wt% Co) and Ti6Al4V/(WC-24 wt% Co) welds were not improved when 20-µm thick Ni interlayers were introduced prior to friction welding. During mechanical testing, the Ni layer retained at the dissimilar joint interface created a region of weakness. 相似文献
90.
Ti-45Al-10Nb合金的高温氧化行为 总被引:4,自引:0,他引:4
研究了Ti—45A1—10Nb(原子分数,%)合金在800-960℃在氧气和空气中的氧化行为.结果表明,该合金具有较好的高温抗氧化性能,其氧化增重速率与铁基耐热不锈钢相似或略优.与Ti—50A1合金相反,Ti-45A1-10Nb合金在空气中的氧化增重速率明显低于在纯氧中的氧化增重速率.X射线衍射与能谱分析表明,Ti-45Al一10Nb合金在氧气中的氧化产物主要有TiO2和Al2O3,但在空气中的氧化产物中有TiN相.这是降低氧化速率的主要原因,同时,合金元素Nb稳定了氧化层中的TiN相,因而提高了合金在空气中的抗氧化性能. 相似文献