全文获取类型
收费全文 | 1516篇 |
免费 | 43篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 60篇 |
综合类 | 2篇 |
化学工业 | 318篇 |
金属工艺 | 44篇 |
机械仪表 | 16篇 |
建筑科学 | 20篇 |
能源动力 | 51篇 |
轻工业 | 179篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 145篇 |
一般工业技术 | 334篇 |
冶金工业 | 307篇 |
原子能技术 | 25篇 |
自动化技术 | 65篇 |
出版年
2023年 | 9篇 |
2022年 | 13篇 |
2021年 | 30篇 |
2020年 | 12篇 |
2019年 | 14篇 |
2018年 | 21篇 |
2017年 | 18篇 |
2016年 | 37篇 |
2015年 | 19篇 |
2014年 | 35篇 |
2013年 | 81篇 |
2012年 | 52篇 |
2011年 | 74篇 |
2010年 | 52篇 |
2009年 | 68篇 |
2008年 | 62篇 |
2007年 | 69篇 |
2006年 | 56篇 |
2005年 | 49篇 |
2004年 | 43篇 |
2003年 | 50篇 |
2002年 | 49篇 |
2001年 | 27篇 |
2000年 | 36篇 |
1999年 | 35篇 |
1998年 | 124篇 |
1997年 | 74篇 |
1996年 | 61篇 |
1995年 | 45篇 |
1994年 | 30篇 |
1993年 | 40篇 |
1992年 | 15篇 |
1991年 | 8篇 |
1990年 | 12篇 |
1989年 | 14篇 |
1988年 | 10篇 |
1987年 | 12篇 |
1986年 | 17篇 |
1985年 | 8篇 |
1984年 | 19篇 |
1983年 | 10篇 |
1981年 | 10篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 8篇 |
1976年 | 14篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 4篇 |
排序方式: 共有1568条查询结果,搜索用时 15 毫秒
1.
A method for estimating the sway angle using an observer has already been proposed. The state observer estimates the sway angle accurately and must use the detected sway angle value. However, the estimated sway angle has an error owing to rope length error, friction force, and wind. Moreover, the container mass cannot be determined, and therefore the observer parameter is not suitable. We already proposed robust antisway control for overcoming rope length error without adding a new sensor. Further, we designed a friction disturbance observer to cancel out the influence of the friction force. In this paper, we first propose a container mass estimation method when a crane system performs rolling up control. The observer parameter can be selected using the estimated mass value. Second, in crane parallel shift control, we propose a robust antisway control even when there is a wind disturbance. We design a wind disturbance observer and propose a wind disturbance estimator to separate the friction observer output from the wind disturbance observer output. We confirm through experiments that the proposed method can reduce vibration. 相似文献
2.
The present paper includes experimental and analytical data on the fracture properties of a nickel-iron superalloy, a ferromagnetic austenite, at 4 K in magnetic fields of 0 and 6 T. The tensile, notch tensile and small punch tests are employed. A finite element analysis is also performed to convert the experimentally measured load-displacement data into useful engineering information. To interpret the results we review the available theory of the influence of magnetic field on the stress intensity factor for a crack in ferromagnetic materials. 相似文献
3.
Polyacrylate gels containing Ag+ and TiO2 nanoparticles are shown to swell under UV light and shrink under visible light in water. In work reported by Tetsu Tatsuma and co‐workers on p. 1249, the TiO2 absorbs UV light and reduces the Ag+, whereas the deposited Ag absorbs visible light and dissolves itself. These redox reactions change the interactions between the polymer chains and eventually the volume of the gel, as shown on the cover. 相似文献
4.
Theoretical analysis based on the calculation of phase diagrams was employed for Fe-Si-Co and Fe-Si-Al ordering systems to
clarify the necessity for the occurrence of phase separation in Fe-base ternary ordering systems. The free energy of Fe-base
ternary ordering alloys where B2 and D03 ordered structures are formed is evaluated statistically using a pairwise interaction approximation up to second nearest
neighbours, taking into account not only the atomic interaction but also the magnetic interaction, based on the Bragg-Williams-Gorsky
model. The calculated phase diagrams are consistent with the experimentally obtained ones. The phase diagram calculation in
this work is useful to predict the equilibrium states of the ternary ordering systems. The phase separation in ordering alloys
is caused by the contribution of excess free energies due to ordering. The influences of ferromagnetism on the two-phase regions
are also demonstrated. 相似文献
5.
Kazuhiko Miyazaki Hirofumi Kasada Masayuki Ohtsuka 《Journal of Infrared, Millimeter and Terahertz Waves》1994,15(10):1669-1674
We succeeded in observing the continuously tunable, pulsed InSb SFR (Spin-Flip Raman) laser emission in the infrared region of 11~16µm (11.4~16.3µm) from only one InSb device, merely by adjusting the pumping wavelength (11 lines from the infrared NH3 laser) and the applied magnetic field (0~80 kGauss). 相似文献
6.
The third-order nonlinear optical susceptibilities, X(3), of TeO2-based glasses containing transition metal oxides (M = Sc2O3, TiO2, V2O5, Nb2O5, MoO3, Ta2O5, and WO3) glasses have been measured by the third harmonic generation (THG) method in order to investigate the effect of the empty d-orbital contributions to the third-order nonlinear optical susceptibilities. It is found that the addition of TiO2, Nb2O5, and WO3 to TeO2 glass increases the X(3) value as well as the refractive index, while others decrease both of them. The positive effect of the TiO2, Nb2O5, or WO3, on the X(3) of TeO2 glass was interpreted in terms of the cationic empty d-orbital contribution. There is an almost linear relation between the X(3) and the term (n2ω+ 2)3.(n2ω -1).Ed/E20 containing three measurable parameters only, irrespective of the kinds of MO, which was derived based on the bond orbital theory developed by M. E. Lines. The largest X(3) value obtained is 1.69 × 10−12 esu for 30NbO2.5.70TeO2 glass, about 60 times larger than that of pure fused silica glass. 相似文献
7.
8.
Shallow and efficient doping of wide band-gap semiconductors has remained one of yet unresolved problems to date. A possible solution to this problem is doping with complexes of a few impurity atoms at a quasi-equilibrium state, which is introduced by controlled cooling of a sample after doping. In this work, (1) we first define a global and quasi-equilibria of our interest based on a simple thermodynamic model for a doped crystal, and then (2) we discuss how the cooling rate affects the probability of impurity-complex formation at a quasi-equilibrium as defined. Our main message is that one should design impurity complexes as small in size as possible which have as large a binding energy as possible. This is a required condition for complex designs when it is difficult to tune the cooling rate. 相似文献
9.
Three IgM class anti-H monoclonal antibodies (1E3, 1E5 and 3H1) were obtained from a BALB/c mouse immunized with human O type saliva. These antibodies were found to agglutinate red cells from O group and A and B subgroups but not from Bombay and para-Bombay individuals whose H antigen was barely detected by anti-H reagents. The agglutination reactions of these antibodies were inhibited by H antigens from human tissues. It was also demonstrated that both 1E3 and 3H1 reacted with H disaccharide (Fuc alpha 1-->2Gal beta), H type 1 (Fuc alpha 1-->2Gal beta 1-->3GlcNAc beta), H type 2 (Fuc alpha 1-->2Gal beta 1-->4GlcNAc beta), H type 3 (Fuc alpha 1-->2Gal beta 1-->3GalNAc alpha) and H type 4 (Fuc alpha 1-->2Gal beta 1-->3GalNAc beta) but not with Lea (Gal beta 1-->3[Fuc alpha 1-->4]GlcNAc beta), Leb (Fuc alpha 1-->2Gal beta 1-->3[Fuc alpha 1-->4]GlcNAc beta), X (Gal beta 1-->4[Fuc alpha-->3]GlcNAc beta) or Y (Fuc alpha 1-->2Gal beta 1-->4[Fuc alpha 1-->3]GlcNAc beta). On the other hand, 1E5 was found to react with H type 1, H type 2, Leb and Y. Because of the unique reactivities against various fucosyl linkages these monoclonal antibodies could be useful not only as anti-H reagents but also as reagents for the structural analysis of fucosylated glycoconjugates. 相似文献
10.
In this study, a new method for calculating the dynamic stress intensity factors of a bimaterial bending specimen with an interface crack is proposed by making use of a line-spring model. A pre-cracked bending specimen is modeled by one-dimensional beam finite elements and a line-spring representing the stiffness or compliance of a cracked part. The proposed method enables the one-dimensional analysis of a two-dimensional crack problem; thus the time variations of the dynamic stress intensity factors of a bimaterial bending specimen with an interface crack can be obtained by making use of a personal computer within a few minutes. The results obtained by the proposed method agree reasonably well with those obtained by the two-dimensional finite element method, although a slight difference in period can be found. The proposed method enables rapid evaluation of dynamic stress intensity factors. So a rapid evaluation system of the dynamic fracture toughness of a bimaterial with an interface crack can be achieved by combining an instrumented impact test apparatus with a computer program based on the proposed method which runs on a personal computer. 相似文献