全文获取类型
收费全文 | 229397篇 |
免费 | 2096篇 |
国内免费 | 710篇 |
专业分类
电工技术 | 4937篇 |
综合类 | 268篇 |
化学工业 | 33838篇 |
金属工艺 | 12361篇 |
机械仪表 | 10911篇 |
建筑科学 | 5807篇 |
矿业工程 | 1177篇 |
能源动力 | 4621篇 |
轻工业 | 18489篇 |
水利工程 | 2273篇 |
石油天然气 | 2153篇 |
武器工业 | 5篇 |
无线电 | 27831篇 |
一般工业技术 | 49341篇 |
冶金工业 | 29846篇 |
原子能技术 | 3474篇 |
自动化技术 | 24871篇 |
出版年
2018年 | 10142篇 |
2017年 | 10825篇 |
2016年 | 6271篇 |
2015年 | 1638篇 |
2014年 | 1889篇 |
2013年 | 6630篇 |
2012年 | 5973篇 |
2011年 | 13442篇 |
2010年 | 12086篇 |
2009年 | 11393篇 |
2008年 | 11530篇 |
2007年 | 13900篇 |
2006年 | 4426篇 |
2005年 | 7984篇 |
2004年 | 6103篇 |
2003年 | 5600篇 |
2002年 | 4594篇 |
2001年 | 4045篇 |
2000年 | 3882篇 |
1999年 | 3712篇 |
1998年 | 6637篇 |
1997年 | 5229篇 |
1996年 | 4472篇 |
1995年 | 3720篇 |
1994年 | 3389篇 |
1993年 | 3209篇 |
1992年 | 2799篇 |
1991年 | 2714篇 |
1990年 | 2628篇 |
1989年 | 2614篇 |
1988年 | 2465篇 |
1987年 | 2166篇 |
1986年 | 2115篇 |
1985年 | 2556篇 |
1984年 | 2316篇 |
1983年 | 2195篇 |
1982年 | 2068篇 |
1981年 | 1991篇 |
1980年 | 1860篇 |
1979年 | 1874篇 |
1978年 | 1770篇 |
1977年 | 2085篇 |
1976年 | 2563篇 |
1975年 | 1583篇 |
1974年 | 1430篇 |
1973年 | 1453篇 |
1972年 | 1196篇 |
1971年 | 1115篇 |
1970年 | 948篇 |
1968年 | 872篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
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
12.
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
13.
14.
A. A. Babenko V. I. Zhuchkov L. A. Smirnov A. V. Sychev A. A. Akberdin A. S. Kim M. F. Vitushchenko A. A. Dobromilov 《Steel in Translation》2015,45(11):883-886
A technology for slag formation in the ladle–furnace unit is considered; the slag is based on the CaO–SiO2–MgO–Al2O3–B2O3 system. This technology permits both microalloying of the steel with boron (reduced from the oxide phase) and desulfurization of the steel. The resulting boron content in the steel is 0.001–0.008%; the sulfur content in low-alloy steel and pipe steel is low (0.004–0.010%); and the consumption of manganese ferroalloys is reduced to 0.5 kg/t for 08кп steel and 1.4 kg/t for 09Г2C steel. In addition, the proposed technology increases the strength of the rolled steel, without loss in its plasticity; and reduces the environmental impact thanks to the replacement of fluorspar by colemanite. 相似文献
15.
16.
17.
The design of a microstrip‐fed annular‐ring slot antenna (ARSA) with circular polarization (CP) radiation is initially studied. To obtain CP radiation with broad 3‐dB axial ratio (AR) bandwidth that can cover the WiMAX 2.3 GHz (2305–2320 MHz, 2345–2360 MHz) and WLAN 2.4 GHz (2400–2480 MHz) bands, a novel technique of extending an inverted L‐shaped slot from the bottom section of the annular‐ring is proposed. To suppress the harmonic modes induced by the CP ARSA, the technique of integrating a defected ground structure into the annular‐ring slot is further introduced. From the measured results, 10‐dB impedance bandwidth and 3‐dB AR bandwidth of 44.86 and 9.68% were achieved by the proposed harmonic suppressed CP ARSA. Furthermore, average gain and radiation efficiency of ~4.7 dBic and 71%, respectively, were also exhibited across the bands of interest. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:337–345, 2015. 相似文献
18.
19.
The dynamic interaction between the mechanical and electrical drive parameters when damage suddenly appears in the mechanical part of a conveyer belt is investigated. The possibility of using the change in the motor’s electrical parameters as a diagnostic signal is assessed. A model for investigating the dynamic processes in the system consisting of the grid, the induction motor, and the conveyer belt is proposed. The grid and induction motor are described by a model of fourth-order state space, whose output is the torque at the motor shaft. The moments of inertia and pliability of the links between the elements in the mechanical part of the conveyer belt are determined. By gradually identifying the elements with the minimum moment of inertia and distributing their moments of inertia and pliabilities among the adjacent elements, we obtain a three-mass system simulating the mechanical part of the conveyer belt. This dynamic model is solved by means of Matlab Simulink software. The energy characteristics of the drive are determined in dynamic processes following a mechanical accident. 相似文献
20.
Advanced technologies and modern high-production machines for underground mining of thick gently dipping coal demand strict adherence to technological discipline, reduction in operational loss and selection of optimized ventilation modes. The authors analyze ventilation schemes used in working areas in thick gently dipping seams in order to reveal influence exerted by the schemes, methods and parameters of ventilation on distribution of air loss in mined-out areas. 相似文献