全文获取类型
收费全文 | 510篇 |
免费 | 8篇 |
国内免费 | 21篇 |
专业分类
电工技术 | 1篇 |
综合类 | 11篇 |
化学工业 | 89篇 |
金属工艺 | 54篇 |
机械仪表 | 53篇 |
建筑科学 | 48篇 |
矿业工程 | 7篇 |
能源动力 | 10篇 |
轻工业 | 4篇 |
石油天然气 | 1篇 |
武器工业 | 2篇 |
无线电 | 10篇 |
一般工业技术 | 218篇 |
冶金工业 | 21篇 |
原子能技术 | 6篇 |
自动化技术 | 4篇 |
出版年
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 13篇 |
2020年 | 4篇 |
2019年 | 7篇 |
2018年 | 8篇 |
2017年 | 17篇 |
2016年 | 6篇 |
2015年 | 10篇 |
2014年 | 13篇 |
2013年 | 27篇 |
2012年 | 7篇 |
2011年 | 37篇 |
2010年 | 18篇 |
2009年 | 24篇 |
2008年 | 32篇 |
2007年 | 27篇 |
2006年 | 34篇 |
2005年 | 25篇 |
2004年 | 15篇 |
2003年 | 34篇 |
2002年 | 21篇 |
2001年 | 21篇 |
2000年 | 17篇 |
1999年 | 13篇 |
1998年 | 18篇 |
1997年 | 17篇 |
1996年 | 12篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 3篇 |
1992年 | 8篇 |
1991年 | 10篇 |
1990年 | 13篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1985年 | 1篇 |
排序方式: 共有539条查询结果,搜索用时 837 毫秒
1.
2.
SiC(w)/TZP+mullite陶瓷复合材料界面和组成设计与力学性能 总被引:2,自引:1,他引:1
本文从理论上分析了SiC(w)TZP+mullite(p)复合材料界面残余热应力及其在基质内的分布规律。提出在SiC(w)表面涂复Al2O3和在PZT中加入mullite(p)联合作用来降低晶须/基质界面残余热应力的界面设计方案,导出SiC(w)和mullite(p)协同补强PZT的匹配条件。制备了SiC(w)/TZP+mullite(p)复合材料并了SiC(w)表面涂层Al2O3厚度和SiC(w 相似文献
3.
The fracture toughness of brittle thermoset resins could be improved significantly by perfectly bonded tough, short fibers through both crack trapping and bridging effects. In this paper, the crack trapping effect was studied through the analysis of the change of strain energy associated with the crack propagation across a regular array of fibers, and the bridging effect was discussed based on the Andersson–Bergkvist model. The fracture resistance increases with the fiber volume fraction, and is independent of the elastic properties of the matrix, the crack length, and the cross-sectional diameter of the fibers. 相似文献
4.
The mechanism of “475°C embrittlement” of a duplex stainless steel was investigated using finite element modelling of the stress distribution at brittle fracture initiation. Brittle fracture initiated at a critical shear stress, which increased with ferrite hardness. The fracture stress was affected by the duplex microstructure. Fracture was nucleated by deformation twins, which were identified using electron back-scatter diffraction. The ductile-to-brittle fracture transition was sensitive to age-hardening and could be described simply by the effect of age-hardening and test temperature on the yield stress. 相似文献
5.
祁帜 《理化检验(物理分册)》2002,38(8):355-359
对断裂的油泵柱塞、轴承外套从成分、组织、工艺等方面进行了检验分析。结果表明,柱塞首先断裂,断裂后的柱塞碎片卡住了轴承外套,使轴承外套过载脆断。而柱塞的断裂是由于热处理不当,造成淬火加热温度过高,使柱塞的显微组织出现粗大的针状马氏体,并引起淬火裂纹,导致柱塞的韧性下降,脆性增大,随着载荷作用和液压油的渗入,裂纹进一步扩展,当裂纹扩展笃柱塞有效载面积承受不了全部工作应力时,发生脆性断裂。 相似文献
6.
双头螺栓失效分析 总被引:4,自引:3,他引:1
金蔚静 《理化检验(物理分册)》2003,39(5):268-270
与汽车电机装配在一起的双头螺栓在拧紧后不久便发生断裂。采用扫描电镜、化学分析、金相检验等方法对失效件进行了检测,同时又进行了氢脆试验验证。结果表明,螺栓在进行表面酸洗及电镀时,氢向金属内部扩散和富集,当氢浓度达到一定临界值后,促使氢致裂纹的产生和扩展。在外应力的作用下,即出现氢脆现象导致螺栓断裂。 相似文献
7.
Tsugio Sato Kenji Dosaka Toshiaki Yoshioka Akitsugu Okuwaki Kazuo Torii Yoshiro Onodera 《Journal of the American Ceramic Society》1992,75(3):552-556
Amorphous CeO2 –ZrO2 gels were prepared by coprecipitation in ammonia solutions. The onset of crystallization of the gels, from calcining in air, was 420°C, while 200° to 250°C in the presence of water and organic solvents such as methanol and ethanol. The sintering behaviors of CeO2 –ZrO2 powders were sensitive to the crystallizing conditions, since hard agglomerates formed when the precipitated gels were crystallized by normal calcination in air, whereas soft agglomerates formed when they were crystallized in water or organic solvents. CeO2 –ZrO2 powders crystallized in methanol and water at 250°C were sintered to full theoretical density at 1150° and 1400°C, respectively, whereas that crystallized by calcination in air at 450°C was sintered to only 95.2% of theoretical density, even at 1500°C. 相似文献
8.
Environmental etch damage to automotive coatings, and scratch and mar of these coatings are an important element of customer satisfaction as well as a significant warranty repair consideration for automotive companies. The conditions that result in environmental etch are examined and a laboratory test proposed. Data from this test are compared to automotive hoods exposed in Florida. The performance of various crosslinking chemistries is discussed and the requirements for improved environmental etch are outlined. Scratch and mar performance of these systems is also reviewed. We have found that coatings respond to physical stress by elastic recovery, by plastic flow and by brittle fracture. Classifying types of damage in this way is important for understanding the chemistry needed for improved scratch and mar of coatings. 相似文献
9.
Kenichi Noguchi Yukihisa Matsuda Manabu Oishi Takaki Masaki Sadao Nakayama Masahiro Mizushina 《Journal of the American Ceramic Society》1990,73(9):2667-2676
Tensile strength of Y2 O3 -stabilized ZrO2 polycrystals (Y-TZP) was measured by a newly developed tensile testing method with a rectangular bar. The tensile strength of Y-TZP was lower than that of the three-point bend strength, and the shape of the tensile strength distribution was quite different from that of the three-point bend strength distribution. It was difficult to predict the distribution curve of the tensile strength using the data of the three-point bend strength by one-modal Weibull distribution. The distribution of the tensile strength was analyzed by two- or three-model Weibull distribution coupled with an analysis of fracture origins. The distribution curve of the three-point bend strength which was estimated by multimodal Weibull distribution agreed favorably with that of the measured three-point bend strength values. A two-modal Weibull distribution function was formulated approximately from the distributions of the tensile and three-point bend strengths, and the estimated two-modal Weibull distribution function for the four-point bend strength agreed well with the measured four-point bend strength. 相似文献
10.
The paper gives some closed form expressions for the strain energy averaged in a finite size volume surrounding the root of
blunt V-shaped notches under Mode I loading. The control volume, reminiscent of Neuber’s concept of elementary structural
volumes, is thought of as dependent on the ultimate tensile strength and the fracture toughness KIC in the case of brittle or quasi-brittle materials subjected to static loads. Expressions for strain energy density under
plane strain conditions and Mode I loading have been derived from an analytical frame recently reported in the literature,
which matches Williams and Creager-Paris’ solutions in the particular cases of plates weakened by sharp V-notches or blunt
cracks (U-notches), respectively. In order to validate a local-strain-energy based approach, a well-documented set of experimental
data recently reported in this journal by Gómez and Elices has been used. Data refer to blunt and sharp V-specimens of PMMA
subjected to static tension loads and characterised by a large variability of notch root radius (from 0 to 4.0 mm) and notch
angle (from 0° to 150°). Critical loads obtained experimentally have been compared with the theoretical ones, estimated here
by keeping constant the mean value of the strain energy in a well-defined small size volume. 相似文献