全文获取类型
收费全文 | 389篇 |
免费 | 15篇 |
国内免费 | 32篇 |
专业分类
综合类 | 26篇 |
化学工业 | 19篇 |
金属工艺 | 179篇 |
机械仪表 | 52篇 |
矿业工程 | 15篇 |
武器工业 | 14篇 |
无线电 | 13篇 |
一般工业技术 | 88篇 |
冶金工业 | 30篇 |
出版年
2024年 | 3篇 |
2023年 | 5篇 |
2022年 | 11篇 |
2021年 | 11篇 |
2020年 | 6篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 14篇 |
2016年 | 14篇 |
2015年 | 26篇 |
2014年 | 26篇 |
2013年 | 14篇 |
2012年 | 17篇 |
2011年 | 27篇 |
2010年 | 20篇 |
2009年 | 19篇 |
2008年 | 12篇 |
2007年 | 55篇 |
2006年 | 40篇 |
2005年 | 21篇 |
2004年 | 14篇 |
2003年 | 18篇 |
2002年 | 12篇 |
2001年 | 10篇 |
2000年 | 9篇 |
1999年 | 5篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 1篇 |
1992年 | 1篇 |
排序方式: 共有436条查询结果,搜索用时 15 毫秒
11.
The pressureless infiltration kinetics was investigated by plotting the infiltration distance as function of the infiltration time. The effects of key process parameters such as time, temperature, Mg content on the pressureless infiltration of silicon carbide particle compacts were studied and quantified. The preform with high volume fraction SiC was obtained by mixing SiC particles with bimodal size distribution, whose diameters are 5 and 50 btm, respectively. The results show that an incubation period exists before infiltration, the influence of temperature on the incubation time exceeds that of Mg content, infiltration rate increases with the increasing temperature and Mg content, infiltration rate decreases as Mg consumes. A model of macroscopical infiltration and microscopical infiltration of liquid alloy in porous SiC preform was proposed. 相似文献
12.
13.
研究了无压渗透法制备电子封装SiCp/Al复合材料过程中,烧结工艺对SiC预制件开孔率、抗压强度的影响,以及渗透工艺对Al液渗透形成复合材料的影响,并对所制备的复合材料热物理性能和表面涂覆进行了评价。结果表明,经1100℃分段烧结的SiC预制件开孔率、抗压强度较好;Al液浇铸温度、保温温度分别在750~850℃、800~900℃的范围时,SiC预制件的渗透效果较好;所制备的55%SiCp/Al复合材料相对密度为98.3%,热膨胀系数在(7.23~9.97)×10-6K^-1之间变化,热导率为146.5~172.3W/(m.K),复合材料表面涂覆性能可行性好。 相似文献
14.
Interface structure and formation mechanism of vacuum-free vibration liquid phase diffusion-bonded joints of SiCp/ZL101A composites 总被引:1,自引:0,他引:1
The vacuum-free vibration liquid phase(VLP) diffusion-bonding of SiCp/ZL101A composites was investigated. The effects of vibration on the interface structure, the phase transformation and the tensile strength of bonded joints were examined. Experimental results show that the oxide film on the surface of the composites is a key factor affecting the tensile strength of boned joints. The distribution of the oxide layers at the interface changes from a continuous line to a discontinuous one during vibration. The tensile strength of the VLP diffusion-bonded joints increases with the vibration time, and is up to the maximum of 172 MPa when the vibration time is 30 s. The phase structure of the bond region changes from the Zn-Al-Cu hyper-eutectic (η (β η) (β η ε)) phases to Al-rich Al-base solid solution (α-Al) with increasing the vibration time. 相似文献
15.
16.
SiCp/2024复合材料棒材半固态挤压是一个典型的半固态触变成形过程,尤其对高固相分数(~60%),更接近于塑性加工中超塑性变形机制.对其加工过程进行了数值模拟,以便揭示高固相体积分数半固态触变成性的规律.研究表明稳态触变挤压的关键是在于保证压力下速度与半固态坯料的凝固速度相协调,只有当变形区坯料保持在固相分数较高固-液态或刚凝固完状态时,才能实现稳态的触变挤压过程;随着挤压温度的升高,挤压力减小其等效应力、等效应变值更均匀,且等效应力减小;随着摩擦系数的减小,平均拉应力值减小. 相似文献
17.
采用快速甩带技术制备了(Al-10Si-20Cu-0.05Ce)-1Ti(质量分数/%)急冷箔状钎料,并对60%体积分数的SiCp/6063Al复合材料进行真空钎焊实验,然后对钎料及接头的显微组织与性能进行测定和分析。结果表明,急冷钎料的微观组织细小、成分均匀,厚80~90μm,主要包含Al、CuAl2、Si和Al2Ti等相。当升高钎焊温度(T/℃)或延长保温时间(t/min),SiCp/钎料界面的润湿性改善,6063Al基体/钎料间互扩散和溶解作用增强,接头连接质量逐渐提高。当T=590℃、t=30min时,接头抗剪强度达到112.6 MPa;当T=590℃、t=50min时,少量小尺寸SiCp因液态钎料排挤而分散于钎缝,因加工硬化而使接头强度递增7.3%。然而,当T≥595℃、t≥60min时,SiCp偏聚于钎缝,导致接头组织恶化,且剪切断裂以脆性断裂为主。综合考虑钎焊成本与接头强度使用要求,确定最佳钎焊工艺为590℃、30min。 相似文献
18.
汤佩钊 《昆明理工大学学报(自然科学版)》1997,22(1):61-65,83
研究了SiCp/ZA30复合材料的摩擦磨损特性。结果表明:SiCp/ZA30复合材料的耐磨性优于高铝锌基合金,并随SiC粒子加入量的增加而增大。 相似文献
19.
The scanning electron microscopy (SEM) analysis results of Si distribution in the interface between SiC reinforcements and aluminum matrix of a stir casting SiCp/Al-Mg-Si composite were presented. Results show that there is Si precipitation deposit on the interface of the composite and Si connects with SiC reinforcements in one side and connects with aluminum matrix in the other side. Si phase plays as a connecting bridge, which contributes to the interfacial combination of SiCp/Al composite. 相似文献
20.
In the present study, the AZ91 alloy reinforced by (submicron + micron) SiCp with four kind volume ratio was fabricated by the semisolid stirring casting technology. The influence of volume ratio between submicron and micron SiCp on the microstructure and mechanical properties of Mg matrix was investigated. Results show that the submicron SiCp is more conducive to grain refinement as compared with micron SiCp. With the increase of volume ratio, the submicron particle dense regions increase and the average grain size decreases. The yield strength of bimodal size SiCp/AZ91 composite is higher than monolithic micron SiCp/AZ91composite. Both ΔσHall–Petch and ΔσCTE increase as the volume ratio changes from 0:10, 0.5:9.5, 1:9 to 1.5:8.5. Among the composite with different volume ratio, the S-1.5 + 10-8.5 composite has the best mechanical properties. The interface debonding is found at the interface of micron SiCp-Mg. As the increase of volume ratio, the phenomenon of interface debonding weakens and the amount of dimples increases. 相似文献