全文获取类型
收费全文 | 196604篇 |
免费 | 2771篇 |
国内免费 | 1921篇 |
专业分类
电工技术 | 3979篇 |
综合类 | 3667篇 |
化学工业 | 26419篇 |
金属工艺 | 14015篇 |
机械仪表 | 10682篇 |
建筑科学 | 5066篇 |
矿业工程 | 1828篇 |
能源动力 | 3420篇 |
轻工业 | 7042篇 |
水利工程 | 2688篇 |
石油天然气 | 3854篇 |
武器工业 | 103篇 |
无线电 | 19955篇 |
一般工业技术 | 43986篇 |
冶金工业 | 15548篇 |
原子能技术 | 2202篇 |
自动化技术 | 36842篇 |
出版年
2022年 | 556篇 |
2021年 | 841篇 |
2020年 | 662篇 |
2019年 | 721篇 |
2018年 | 21339篇 |
2017年 | 21064篇 |
2016年 | 13941篇 |
2015年 | 2061篇 |
2014年 | 1735篇 |
2013年 | 3308篇 |
2012年 | 7231篇 |
2011年 | 18394篇 |
2010年 | 16728篇 |
2009年 | 13772篇 |
2008年 | 14241篇 |
2007年 | 17058篇 |
2006年 | 2281篇 |
2005年 | 6458篇 |
2004年 | 4560篇 |
2003年 | 4389篇 |
2002年 | 3242篇 |
2001年 | 2211篇 |
2000年 | 1738篇 |
1999年 | 1426篇 |
1998年 | 2410篇 |
1997年 | 1897篇 |
1996年 | 1636篇 |
1995年 | 1165篇 |
1994年 | 934篇 |
1993年 | 900篇 |
1992年 | 702篇 |
1991年 | 680篇 |
1990年 | 554篇 |
1989年 | 512篇 |
1988年 | 416篇 |
1987年 | 419篇 |
1986年 | 387篇 |
1985年 | 395篇 |
1984年 | 317篇 |
1983年 | 308篇 |
1982年 | 309篇 |
1981年 | 302篇 |
1980年 | 364篇 |
1979年 | 355篇 |
1978年 | 297篇 |
1977年 | 422篇 |
1976年 | 647篇 |
1975年 | 310篇 |
1973年 | 312篇 |
1968年 | 335篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
V. E. Gromov A. M. Glezer K. V. Morozov Yu. F. Ivanov K. V. Volkov 《Russian Metallurgy (Metally)》2015,2015(13):1094-1097
A layer-by-layer analysis of the structures, the phase compositions, and the defect substructures of differentially hardened rails has been carried by optical and transmission electron microscopy. It is found that the material volume of the rail head fillet is cooled faster than the volume located along the central axis. 相似文献
3.
Molecular structure and granule morphology of native and heat‐moisture‐treated pinhão starch 下载免费PDF全文
Vania Z. Pinto Khalid Moomand Nathan L. Vanier Rosana Colussi Franciene A. Villanova Elessandra R. Zavareze Loong‐Tak Lim Alvaro R. G. Dias 《International Journal of Food Science & Technology》2015,50(2):282-289
Pinhão seed is an unconventional source of starch and the pines grow up in native forests of southern Latin America. In this study, pinhão starch was adjusted at 15, 20 and 25% moisture content and heated to 100, 110 and 120 °C for 1 h. A decrease in λ max (starch/iodine complex) was observed as a result of increase in temperature and moisture content of HMT. The ratio of crystalline to amorphous phase in pinhão starch was determined via Fourier transform infra red by taking 1045/1022 band ratio. A decrease in crystallinity occurred as a result of HMT. Polarised light microscopy indicated a loss of birefringence of starch granules under 120 °C at 25% moisture content. Granule size distribution was further confirmed via scanning electron microscopy which showed the HMT effects. These results increased the understanding on molecular and structural properties of HMT pinhão starch and broadened its food and nonfood industrial applications. 相似文献
4.
5.
6.
7.
使用气-质联用仪测定餐饮废油生物柴油(WCME)和-10号柴油(-10PD)的组成,使用冷滤点试验器和运动黏度试验器测定WCME的低温流动性,同时使用调合、添加低温流动性改进剂的方法改进WCME的低温流动性。实验结果表明,WCME主要由饱和脂肪酸甲酯和不饱和脂肪酸甲酯组成,质量分数分别为27.63%和71.81%;WCME冷滤点为0℃,运动黏度(40℃)为4.41mm2/s;WCME与-10PD调合后,冷滤点降低,其中B20的冷滤点最低,为-13℃,运动黏度随着WCME的体积分数的减少,逐渐接近-10PD的运动黏度。通过添加低温流动性改进剂,WCME,B10,B20的冷滤点分别从0,-8,-13℃降至-4,-26,-25℃。 相似文献
8.
V. I. Zubkov O. V. Kucherova I. N. Yakovlev A. V. Solomonov 《Russian Microelectronics》2015,44(3):203-209
An automated system for integrated electrophysical and optical studies of semiconductor nanoheterostructures, which operates in a wide temperature range from 15 to 475 K, is designed. The setup is intended to measure the temperature and frequency admittance and electroluminescence spectra of light-emitting diode and laser chips formed on substrates of diameter up to 50.2 mm, and the distribution of parameters over the wafer. The setup includes the closed-cycle helium cryogenic station, LCR meter, and temperature controller. The characterization results of nanoheterostructures with InGaN/GaN multiple quantum wells, which are used for creating highly efficient white and blue light-emitting diodes, are presented. 相似文献
9.
I. N. Andronov Yu. I. Ryabkov N. P. Bogdanov N. A. Severova A. N. Danilov I. V. Churilina 《Russian Metallurgy (Metally)》2015,2015(10):778-784
The influence of the thermal cycling conditions on the thermal-cycling creep of a TN-1 alloy and the related irreversible deformations is studied. The conditions under which an anomalous increase in the irreversible deformations begins are determined. The structural mechanism of the irreversible deformations of an equiatomic alloy is shown to be analogous to the structural mechanism of metal creep at high temperatures: it predominantly has a dislocation character. It is proposed to use the effect of anomalous increase in the deformation of materials with reversible martensitic transformations for forming parts made of these materials at low temperatures. 相似文献
10.
V. A. Eremenko V. N. Karpov V. V. Timonin N. G. Barnov I. O. Shakhtorin 《Journal of Mining Science》2015,51(6):1113-1125
The authors have determined the causes of drop in performance of induced block caving using fans of blastholes 105 mm in diameter and single blastholes 250 mm in diameter, as well as the sources of increased drilling cost and expansion of start-up time of production blocks in Abakan underground mine. Alternatives of improvement in drilling efficiency under current conditions are discussed. 相似文献