全文获取类型
收费全文 | 18808篇 |
免费 | 308篇 |
国内免费 | 382篇 |
专业分类
电工技术 | 570篇 |
综合类 | 314篇 |
化学工业 | 5003篇 |
金属工艺 | 1748篇 |
机械仪表 | 1029篇 |
建筑科学 | 1155篇 |
矿业工程 | 136篇 |
能源动力 | 2502篇 |
轻工业 | 811篇 |
水利工程 | 59篇 |
石油天然气 | 397篇 |
武器工业 | 102篇 |
无线电 | 1046篇 |
一般工业技术 | 3079篇 |
冶金工业 | 591篇 |
原子能技术 | 380篇 |
自动化技术 | 576篇 |
出版年
2024年 | 16篇 |
2023年 | 347篇 |
2022年 | 491篇 |
2021年 | 516篇 |
2020年 | 502篇 |
2019年 | 458篇 |
2018年 | 473篇 |
2017年 | 545篇 |
2016年 | 513篇 |
2015年 | 603篇 |
2014年 | 995篇 |
2013年 | 1473篇 |
2012年 | 822篇 |
2011年 | 1604篇 |
2010年 | 1079篇 |
2009年 | 1154篇 |
2008年 | 1144篇 |
2007年 | 1024篇 |
2006年 | 809篇 |
2005年 | 746篇 |
2004年 | 653篇 |
2003年 | 549篇 |
2002年 | 436篇 |
2001年 | 313篇 |
2000年 | 318篇 |
1999年 | 323篇 |
1998年 | 324篇 |
1997年 | 263篇 |
1996年 | 210篇 |
1995年 | 186篇 |
1994年 | 141篇 |
1993年 | 93篇 |
1992年 | 74篇 |
1991年 | 67篇 |
1990年 | 52篇 |
1989年 | 42篇 |
1988年 | 32篇 |
1987年 | 20篇 |
1986年 | 15篇 |
1985年 | 20篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 16篇 |
1981年 | 11篇 |
1980年 | 4篇 |
1974年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Stratis V. Sotirchos 《Chemical Engineering Communications》1985,39(1):259-276
The effects of thermal radiation on the pseudosteady state and transient behavior of porous char particles exposed to an oxygen containing environment are investigated. The numerical simulation results show that particles that do not interchange radiant energy with their environment are characterized by wider ambient temperature regions where multiple steady states exist, higher combustion rates, and lower burning times 相似文献
52.
本文用不同的测试技术和方法测定了锗酸铋(BGO)单晶的比热(300~800K)热膨胀系数(100~1100K)和导温系数(140~700K),进而导出了 BGO 单晶不同温度下的导热系数、定容比热、德拜温度和格虑内森数。本文还对 BGO 单晶热物理性质的变化规律作了理论解释。 相似文献
53.
Kazutaka Chibana Chaedong Kang Masashi Okada Koji Matsumoto Tetsuo Kawagoe 《International Journal of Refrigeration》2002,25(2):83
Water-silicone oil emulsion with an additive, (C2H5O)3SiC3H6NH2, was examined as a heat storage material. A spiral tube used as a heat exchanger was immersed in a low temperature bath and the emulsion was circulated in the tube to make ice continuously. Ice was separated from the ice–liquid suspension in an outlet tank. The amount of formed ice, the temperatures of the inlet and the outlet of the heat exchanger, and the temperatures in the tube wall were measured and the overall heat transfer coefficient and the heat flux through the tube were calculated. Experiments were carried out, varying the flow rate, the temperature of cooling brine, and the thickness of tube wall. The condition under which slurry ice was formed continuously without adhesion of ice to the cooling wall was clarified. Though decrease in the thermal resistance of the tube increased the rate of ice formation or raised the brine temperature, it narrowed the range of the flow rate and of the brine temperature in which slurry ice was formed continuously. 相似文献
54.
The objective of the present study is to develop multi-functioned coating to the components, which are made of copper with electroplated Ni and are widely used for steel making industry. In this paper, we report the mechanical and thermal properties of Ni based superalloys with carbide sprayed by high velocity oxygen fuel (HVOF), and the detailed effects of sprayed material, spraying conditions, and initial powder structure on these properties. It was found that, among commercial Ni self-fluxing alloys (without fusing treatment), coating with a carbon content of 0.58 mass% had the most preferable properties, with a good balance of the hardness, strength, and thermal shock resistance. The thermal shock resistance depended not only on the strength of the coating but also on the volume contraction when tested at high temperatures. For the several developed Ni based superalloys with carbide, Ni20Cr8Mo5Fe–WC and Ni16Cr15Mo3–WC demonstrated the prominent adhesion strength and thermal shock resistance with high Galvanic corrosion resistance through optimized spraying condition. Also, 20 mass% NiCr–Cr3C2 coating sprayed by using employed relatively small primary particle succeeded in achieving the multi-superior properties; high adhesion strength, high corrosion resistance and thermal shock resistance. 相似文献
55.
夏季 ,室外气候诸因素经过不同途径 ,对室内的影响会有差异。了解这些差异有助于在设计时把握主要问题。讨论在住宅隔热设计中 ,针对不同的室内条件 ,应优先考虑的因素及相应的设计对策。 相似文献
56.
The coupled system of three partial differential equations governing a flexible shallow shell dynamics is analysed. No any prior assumptions about the temperature distribution through the shell thickness are applied. The efficiency of the method used here when applied to the solution of integral-differential equations with different dimensions (three-dimensional equations related to the Kirchhoff-Love model) and of different type (heat transfer equations and the hyperbolic equations of shell theory) is demonstrated. Many computational results are reported and discussed. 相似文献
57.
58.
M.A.R. Alves 《Microelectronics Journal》2005,36(1):51-54
We developed a process to obtain sharper silicon tips by employing anisotropic etching in a KOH solution followed by SF6 plasma etch. The tips were further sharpened using the established thermal oxidation technique to decrease the cone angle and, therefore, obtain smaller curvature radii. We have analyzed the impact of such changes in geometry on a figure of merit associated with the field emission characteristics. An increase in the figure of merit by a factor of three was found in relation to the tips before sharpening. 相似文献
59.
本文在理论和试验两个方面探讨了离子注入中的热效应和温升现象。注入样品的温升对离子注入层的性能有直接影响。分析了理论计算注入样品温升的一些情况。给出了实际测量注入样品温升的几种试验方法。阐明了控制注入样品温升的若干可能途径。 相似文献
60.