全文获取类型
收费全文 | 306篇 |
免费 | 3篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 56篇 |
金属工艺 | 13篇 |
机械仪表 | 17篇 |
建筑科学 | 3篇 |
能源动力 | 4篇 |
轻工业 | 16篇 |
水利工程 | 2篇 |
石油天然气 | 9篇 |
无线电 | 30篇 |
一般工业技术 | 53篇 |
冶金工业 | 22篇 |
原子能技术 | 14篇 |
自动化技术 | 69篇 |
出版年
2023年 | 3篇 |
2022年 | 16篇 |
2021年 | 10篇 |
2020年 | 10篇 |
2019年 | 4篇 |
2018年 | 12篇 |
2017年 | 8篇 |
2016年 | 13篇 |
2015年 | 6篇 |
2014年 | 10篇 |
2013年 | 25篇 |
2012年 | 20篇 |
2011年 | 28篇 |
2010年 | 20篇 |
2009年 | 14篇 |
2008年 | 13篇 |
2007年 | 4篇 |
2006年 | 8篇 |
2005年 | 12篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 12篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 4篇 |
1987年 | 6篇 |
1986年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1975年 | 3篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有309条查询结果,搜索用时 9 毫秒
21.
22.
A vector (multicriterion) problem of integer linear programming is considered on a finite set of feasible solutions. A metric
lp, 1 ≤ p ≤ ∞, is defined on the parameter space of the problem. A formula of the maximum permissible level of perturbations
is obtained for the parameters that preserve the efficiency (Pareto optimality) of a given solution. Necessary and sufficient
conditions of two types of stability of the problem are obtained as corollaries.
This work has been carried out with financial support from the Belgosuniversity within the framework of the Intercollegiate
Program “Fundamental and Applied Investigations” (project No. 492/28).
__________
Translated from Kibernetika I Sistemnyi Analiz, No. 4, pp. 175–181, July–August 2006. 相似文献
23.
Masoud Ebrahimzadeh Sari Granroth Sami Vuori Marko Punkkinen Mikko Miettinen Risto Punkkinen Mikhail Kuzmin Pekka Laukkanen Mika Lastusaari Kalevi Kokko 《Advanced Engineering Materials》2023,25(19):2300762
Manufacturing a low-resistive Ohmic metal contact on p-type InP crystals for various applications is a challenge because of the Fermi-level pinning via surface defects and the diffusion of p-type doping atoms in InP. Development of wet-chemistry treatments and nanoscale control of p-doping for InP surfaces is crucial for decreasing the device resistivity losses and durability problems. Herein, a proper combination of HCl-based solution immersion, which directly provides an unusual wet chemical-induced InP(100)c(2 × 2) atomic structure, and low-temperature Mg-surface doping of the cleaned InP before Ni-film deposition is demonstrated to decrease the contact resistivity of Ni/p-InP by the factor of 10 approximately as compared to the lowest reference value without Mg. Deposition of the Mg intermediate layer on p-InP and postheating of Mg/p-InP at 350 °C, both performed in ultrahigh-vacuum (UHV) chamber, lead to intermixing of Mg and InP elements according to X-ray photoelectron spectroscopy. Introducing a small oxygen gas background (O2 ≈ 10−6 mbar) in UHV chamber during the postheating of Mg/p-InP enhances the indium outdiffusion and provides the lowest contact resistivity. Quantum mechanical simulations indicate that the presence of InP native oxide or/and metal indium alloy at the interface increases In diffusion. 相似文献
24.
Stefan‐Ovidiu Dima Tanase Dobre Olga Chetraru Cristian‐Andi Nicolae Catalin‐Ilie Spataru Andrei Sarbu 《Polymer Engineering and Science》2014,54(7):1484-1494
There are presented results regarding a new set of molecularly imprinted polymers (MIPs) based on acrylonitrile:acrylic acid (AN:AA) copolymer matrix. As template, it was used sclareol, an important anticancer bioactive compound, never used before for molecular imprinting. An emerging and insufficient studied MIP preparation method, namely the phase inversion, was used to prepare 0.8 mm spherical sclareol MIPs (S‐MIPs). Three AN:AA copolymers, having the initial monomer ratios 90:10, 80:20, and 70:30, were synthesized by radical copolymerization in emulsion, without emulsifier. After that, each copolymer was dissolved in the presence of the template (sclareol) in dimethylformamide. The imprinting and the morphology of these new materials were analyzed by rheology, elemental analysis, infrared spectroscopy, size exclusion chromatography, thermogravimetric analysis, differential scanning calorimetry, batch rebinding tests, and Scatchard analysis. The conclusion was that the AN:AA‐80:20 matrix proved to be the optimized solution between high rigidity (given by the AN segments) and high affinity for the template (given by AA segments), the average imprinting factor for this system being 2.67. POLYM. ENG. SCI., 54:1484–1494, 2014. © 2013 Society of Plastics Engineers 相似文献
25.
We consider the following type of online variance minimization problem: In every trial t our algorithms get a covariance matrix C
t
and try to select a parameter vector w
t−1 such that the total variance over a sequence of trials ?t=1T (wt-1)T Ctwt-1\sum_{t=1}^{T} (\boldsymbol {w}^{t-1})^{\top} \boldsymbol {C}^{t}\boldsymbol {w}^{t-1} is not much larger than the total variance of the best parameter vector u chosen in hindsight. Two parameter spaces in ℝ
n
are considered—the probability simplex and the unit sphere. The first space is associated with the problem of minimizing
risk in stock portfolios and the second space leads to an online calculation of the eigenvector with minimum eigenvalue of
the total covariance matrix ?t=1T Ct\sum_{t=1}^{T} \boldsymbol {C}^{t}. For the first parameter space we apply the Exponentiated Gradient algorithm which is motivated with a relative entropy regularization.
In the second case, the algorithm has to maintain uncertainty information over all unit directions u. For this purpose, directions are represented as dyads uu
⊤ and the uncertainty over all directions as a mixture of dyads which is a density matrix. The motivating divergence for density
matrices is the quantum version of the relative entropy and the resulting algorithm is a special case of the Matrix Exponentiated
Gradient algorithm. In each of the two cases we prove bounds on the additional total variance incurred by the online algorithm
over the best offline parameter. 相似文献
26.
L. V. Kuzmin V. A. Morozov S. O. Starkov B. A. Khadzhi 《Journal of Communications Technology and Electronics》2006,51(11):1283-1289
The models of indoor multipath propagation of wideband and ultrawideband (UWB) signals are considered. Application of these models is recommended by an IEEE working group. In the framework of one of the models corresponding to the line-of-sight conditions, the algorithms for reception of UWB chaotic signals in the presence of reflection from multiple surfaces (echo signals) are proposed and analyzed. The efficiency of reception techniques is estimated from the viewpoint of the error probabilities. Limitations caused by the specific properties of echo signals are revealed, and the methods for improvement of reception quality are discussed. 相似文献
27.
28.
V. A. Sadykov S. N. Pavlova N. F. Saputina I. A. Zolotarskii N. A. Pakhomov E. M. Moroz V. A. Kuzmin A. V. Kalinkin 《Catalysis Today》2000,61(1-4):93-99
A specially designed tubular microreactor with independent control of feed preheat as well as catalyst temperature and allowing to rapidly quench reaction products was used to test performance of supported Pt-based monolithic catalysts in the reaction of propane oxidative dehydrogenation at short contact times. To minimize the impact of undesired homogeneous reactions capable of decreasing propylene selectivity, proprietary straight-channel thin-wall high cell density corundum micromonoliths were chosen as supports. Catalytic properties of supported platinum were modified by using promoters known as dehydrogenation catalysts (tin, zinc aluminate spinel, transition metal pyrophosphates) as well as by tuning reaction mixture composition (propane/oxygen ratio, water and hydrogen content). In the operation temperature range up to 900°C with contact times 0.03–0.1 s, ethylene/propylene selectivities were found to strongly depend upon the chemical composition of the active component and type of feed. The results thus obtained demonstrate that for Pt-based catalysts, propylene yield can be substantially improved by suppressing secondary reactions of deep oxidation and cracking. 相似文献
29.
Technical Physics Letters - An experimental investigation of the multipath propagation of ultrawideband (UWB) microwave chaotic radio pulses in a wireless channel has been carried out. Based on the... 相似文献
30.