全文获取类型
收费全文 | 22108篇 |
免费 | 2794篇 |
国内免费 | 1924篇 |
专业分类
电工技术 | 2175篇 |
综合类 | 2010篇 |
化学工业 | 2343篇 |
金属工艺 | 2851篇 |
机械仪表 | 1641篇 |
建筑科学 | 3630篇 |
矿业工程 | 1312篇 |
能源动力 | 485篇 |
轻工业 | 821篇 |
水利工程 | 934篇 |
石油天然气 | 988篇 |
武器工业 | 323篇 |
无线电 | 1037篇 |
一般工业技术 | 3644篇 |
冶金工业 | 1053篇 |
原子能技术 | 258篇 |
自动化技术 | 1321篇 |
出版年
2024年 | 111篇 |
2023年 | 334篇 |
2022年 | 700篇 |
2021年 | 869篇 |
2020年 | 901篇 |
2019年 | 815篇 |
2018年 | 702篇 |
2017年 | 936篇 |
2016年 | 935篇 |
2015年 | 990篇 |
2014年 | 1455篇 |
2013年 | 1557篇 |
2012年 | 1701篇 |
2011年 | 1790篇 |
2010年 | 1362篇 |
2009年 | 1375篇 |
2008年 | 1172篇 |
2007年 | 1345篇 |
2006年 | 1354篇 |
2005年 | 996篇 |
2004年 | 874篇 |
2003年 | 758篇 |
2002年 | 683篇 |
2001年 | 515篇 |
2000年 | 424篇 |
1999年 | 383篇 |
1998年 | 326篇 |
1997年 | 282篇 |
1996年 | 207篇 |
1995年 | 176篇 |
1994年 | 144篇 |
1993年 | 120篇 |
1992年 | 99篇 |
1991年 | 79篇 |
1990年 | 68篇 |
1989年 | 54篇 |
1988年 | 41篇 |
1987年 | 22篇 |
1986年 | 14篇 |
1985年 | 32篇 |
1984年 | 15篇 |
1983年 | 18篇 |
1982年 | 13篇 |
1980年 | 9篇 |
1979年 | 14篇 |
1963年 | 4篇 |
1961年 | 5篇 |
1960年 | 6篇 |
1959年 | 7篇 |
1955年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
131.
对新冶钢动力厂制氧机组配套的原料空气压缩机故障现象进行了原因分析,并有针对性地提出了处理措施,经运行检验,故障基本消除。 相似文献
132.
The effect of processing conditions on the yield and failure behavior of an aliphatic polyketone terpolymer was studied. Testing and characterization were performed on samples that were extruded in the form of hollow cylinders. We performed the extrusion process at different shear rates and at different cooling rates to assess the effect that process conditions had on the polymer properties. We performed biaxial testing on the samples to characterize the failure envelopes, including the ductile–brittle transition condition for each process condition. The effect of shear rate was negligible, whereas the cooling rate significantly affected the failure behavior. To explain these differences in behavior, we performed characterization via differential scanning calorimetry, wide‐angle X‐ray diffraction, attenuated total reflection IR spectroscopy, dynamic mechanical thermal analysis, scanning electron microscopy, and residual stress measurements. A broad glass transition was found for all samples at temperatures higher than previously reported for this material. Alteration of the processing conditions did not influence the crystalline phase (percentage crystallinity, crystalline orientation, crystallite size, etc.). A change in spherulitic structure was also observed with altered cooling rate and is suggested to have contributed to the change in failure behavior. Residual stresses also affected the behavior of all samples. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 318–334, 2002; DOI 10.1002/app.10334 相似文献
133.
对川南矿区使用的5ZV25J-10160联组窄V胶带的损坏情况进行了观察分析,主要损坏原因有:胶带V形夹角与带轮轮槽夹角不一致,胶带顶部宽度与带轮轮槽开口宽度不符合要求,在传递动力中造成带轮顶部与胶带联结层接触而单根胶带悬空;胶带硫化质量差、配组不当;胶带及带轮安装、调校未达到要求。对此提出如下改进措施:规定胶带V形夹角和带轮轮槽夹角均为40°,单根胶带顶部宽25mm,带轮轮槽开口宽23.4mm;胶带必须严格按规定配组、安装、调校。实践证明,经改进后胶带传动平稳,无异常损坏。 相似文献
134.
低噪声GaAs FET和功率GaAs FET经中子辐射都未发生致命性的通或断失效,直流偏置伏态下,其失效模式仅仅表现为源漏饱和电流IDSS的退化降低,据此提出了IDSS退化失效与快中子注量φn之间的解析关键式lny=a+blnφ。 相似文献
135.
文中应用简单高阶剪切层合理论和大变形理论对各向异性纤维增强的矩形橡胶复合材料层合板进行了几何非线性分析.与线性理论相比,本文作者进行的层合板大变形状态的几何非线性分析和所计算的层板应力分布,更具有准确性. 相似文献
136.
137.
138.
139.
Bahman Bohloli Bo Ronge Gunnar Gustafson 《Bulletin of Engineering Geology and the Environment》2002,61(1):43-47
Mechanical testing and ultrasonic measurements were used to establish the properties of metamorphic rocks in different directions
of the foliation plane. Tests were undertaken on 42 mm diameter specimens cored at right angles to the foliation of gneissic
rocks from southwest Sweden. Ultrasonic and tensile testing was carried out in three diametral directions and the data for
each direction were compared. Coefficients, failure load anisotropy and velocity anisotropy were obtained. An anisotropy coefficient
of 3% was detected by ultrasonic measurements, while the Brazilian tests indicated 15%. The study has shown that an anisotropy
coefficient of the foliation plane is present, albeit small.
Electronic Publication 相似文献
140.
Failure analysis and a study of the wear mechanism were performed on a heavily loaded carburized gear with some unusual features. The analysis showed that the different failure forms on the tooth surface of the gear were dependent on the sub-surface shearing stress, the lubrication conditions and the surface roughness. Delaminations formed on the addendum surface were the main reason for the gear failure. A suggestion for improvement has been tried, and a desirable result has been obtained. 相似文献