全文获取类型
收费全文 | 313721篇 |
免费 | 80039篇 |
国内免费 | 52091篇 |
专业分类
电工技术 | 36127篇 |
技术理论 | 11篇 |
综合类 | 30479篇 |
化学工业 | 44273篇 |
金属工艺 | 31866篇 |
机械仪表 | 14895篇 |
建筑科学 | 22809篇 |
矿业工程 | 16995篇 |
能源动力 | 11781篇 |
轻工业 | 29626篇 |
水利工程 | 9982篇 |
石油天然气 | 18979篇 |
武器工业 | 4811篇 |
无线电 | 45250篇 |
一般工业技术 | 44363篇 |
冶金工业 | 12579篇 |
原子能技术 | 2785篇 |
自动化技术 | 68240篇 |
出版年
2024年 | 3249篇 |
2023年 | 6291篇 |
2022年 | 8845篇 |
2021年 | 10955篇 |
2020年 | 12611篇 |
2019年 | 20922篇 |
2018年 | 22780篇 |
2017年 | 24371篇 |
2016年 | 23898篇 |
2015年 | 24534篇 |
2014年 | 24448篇 |
2013年 | 24905篇 |
2012年 | 25209篇 |
2011年 | 22398篇 |
2010年 | 20100篇 |
2009年 | 17038篇 |
2008年 | 14904篇 |
2007年 | 14047篇 |
2006年 | 12479篇 |
2005年 | 11196篇 |
2004年 | 11934篇 |
2003年 | 9972篇 |
2002年 | 9372篇 |
2001年 | 8253篇 |
2000年 | 7740篇 |
1999年 | 7647篇 |
1998年 | 6473篇 |
1997年 | 5656篇 |
1996年 | 5386篇 |
1995年 | 5085篇 |
1994年 | 4243篇 |
1993年 | 3637篇 |
1992年 | 3331篇 |
1991年 | 2440篇 |
1990年 | 1960篇 |
1989年 | 1800篇 |
1988年 | 1373篇 |
1987年 | 531篇 |
1986年 | 429篇 |
1985年 | 298篇 |
1984年 | 217篇 |
1983年 | 140篇 |
1982年 | 209篇 |
1981年 | 180篇 |
1980年 | 139篇 |
1976年 | 243篇 |
1975年 | 208篇 |
1972年 | 242篇 |
1971年 | 135篇 |
1960年 | 206篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
The effects of halide-and sulfur-containing additives on iron corrosion in 1 M H2SO4 in the presence of nucleophilic o-hydroxyazomethine derivatives are studied. Dependences of the inhibition factor (as well as its sensitivity to a change in
the polarity of the substituents) and the effective activation energy on the nature and concentration of both the groups of
additives are interpreted in terms of the Linear Gibbs Energy Relation (LGER) and the principle of Hard and Soft Acids and
Bases (HSAB).
Original Russian Text ? V.P. Grigor’ev, V.V. Boginskaya, 2006, published in Zashchita Metallov, 2006, Vol. 42, No. 6, pp.
627–631. 相似文献
992.
Yu. V. Alekseev G. Yu. Alekseev V. A. Bityurin A. V. Plaskeev 《Protection of Metals》2006,42(6):526-531
A simplified topokinetic dissolution model of a solid taking into account the correlation between the dissolution rate and
the atomic surface topography enables one to interpret a linear (in semilogarithmic coordinates) segment of the steady-state
curves of the active anodic dissolution of metals. Its slope corresponds to the product of a concentration of kinks and the
elementary reaction rate, both of which exponentially depend on the potential, rather than a simple (Tafel) elementary rate
of the atom dissolution at a semi-crystal kink.
Original Russian Text ? Yu.V. Alekseev, G.Yu. Alekseev, V.A. Bityurin, A.V. Plaskeev, 2006, published in Zashchita Metallov,
2006, Vol. 42, No. 6, pp. 568–573. 相似文献
993.
Z.M. Zhong J. Chen P. Zhong J.B. Wu 《The International Journal of Advanced Manufacturing Technology》2006,28(9):855-862
As the result of vibration emission in air, a machine sound signal carries important information about the working condition
of machinery. But in practice, the sound signal is typically received with a very low signal-to-noise ratio. To obtain features
of the original sound signal, uncorrelated sound signals must be removed and the wavelet coefficients related to fault condition
must be retrieved. In this paper, the blind source separation technique is used to recover the wavelet coefficients of a monitored
source from complex observed signals. Since in the proposed blind source separation (BSS) algorithms it is generally assumed
that the number of sources is known, the Gerschgorin disk estimator method is introduced to determine the number of sound
sources before applying the BSS method. This method can estimate the number of sound sources under non-Gaussian and non-white
noise conditions. Then, the partial singular value analysis method is used to select these significant observations for BSS
analysis. This method ensures that signals are separated with the smallest distortion. Afterwards, the time-frequency separation
algorithm, converted to a suitable BSS algorithm for the separation of a non-stationary signal, is introduced. The transfer
channel between observations and sources and the wavelet coefficients of the source signals can be blindly identified via
this algorithm. The reconstructed wavelet coefficients can be used for diagnosis. Finally, the separation results obtained
from the observed signals recorded in a semi-anechoic chamber demonstrate the effectiveness of the presented methods . 相似文献
994.
995.
1. Introduction Side-wall acoustic logging tools, such as the Segmented Bond Tool (SBT) from Baker Atlas and the tools for open hole measurements, utilize acoustic transducers mounted on six pads to make compensated acoustic velocity and attenuation measurements which are not affected by mud weight, gas cut, fast formation effects, casing surface conditions or reasonable tool de- centralizing. Studies on the wave fields generated by these tools are very important to tool design and data int… 相似文献
996.
1. Introduction Seismic physical modeling technology is an important method for the research on seismic exploration theory and methods. In seismic physical experiments, the earth, mantle or field site are scaled down to physical models according to the similarity principle, and then the seismic field and its variation are observed in the laboratory for the research work on the theories and methods of the earth structure, earthquake forecasting, energy and mineral resource exploration, and engi… 相似文献
997.
998.
引入空分设备“有效产品成本”概念,以气体成本算法和液体成本算法对空分设备正常产品单位成本和有效产品单位成本进行了比较,举例计算了液化装置的产品成本,提出利用“有效产品成本”概念来组织空分设备生产。 相似文献
999.
The composition of yellow bronze coatings deposited from acidic sulfate solutions added with polyether laprol and the electrodeposition
conditions are studied by voltammetry and XPS. It is found that halides in rather low (micromolar) concentrations affect significantly
the partial electrodeposition processes. Chlorides increases cathodic polarization, widen the current window of the yellow
bronze electrodeposition, and favor the increase in tin content of the coatings. Bromides narrow the current window, lower
the tin content in the coatings, and hinder the yellow bronze surface oxidation. Iodides inhibit the copper electroreduction
markedly, which makes the yellow bronze deposition practically impossible.
Original Russian Text ? Z. Mockus, S. Kanapeckaité, V. Jasulaitiené, A. Survila, 2006, published in Zashchita Metallov, 2006,
Vol. 42, No. 5, pp. 526–531. 相似文献
1000.
信息技术的发展及其在军事领域的应用,改变了未来战争的作战方式,使其在作战理念、作战手段、作战空间以及作战实施方面呈现出不同于传统作战方式的特点。本文对信息时代的作战特点进行了分析总结,并在此基础上对加强我军信息化建设途径进行了探讨。 相似文献