全文获取类型
收费全文 | 1444篇 |
免费 | 89篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 25篇 |
综合类 | 4篇 |
化学工业 | 355篇 |
金属工艺 | 42篇 |
机械仪表 | 60篇 |
建筑科学 | 59篇 |
矿业工程 | 3篇 |
能源动力 | 57篇 |
轻工业 | 220篇 |
水利工程 | 5篇 |
石油天然气 | 20篇 |
无线电 | 111篇 |
一般工业技术 | 205篇 |
冶金工业 | 158篇 |
原子能技术 | 14篇 |
自动化技术 | 208篇 |
出版年
2023年 | 7篇 |
2022年 | 35篇 |
2021年 | 52篇 |
2020年 | 38篇 |
2019年 | 56篇 |
2018年 | 49篇 |
2017年 | 49篇 |
2016年 | 68篇 |
2015年 | 44篇 |
2014年 | 64篇 |
2013年 | 96篇 |
2012年 | 77篇 |
2011年 | 93篇 |
2010年 | 71篇 |
2009年 | 55篇 |
2008年 | 54篇 |
2007年 | 53篇 |
2006年 | 33篇 |
2005年 | 33篇 |
2004年 | 26篇 |
2003年 | 27篇 |
2002年 | 22篇 |
2001年 | 14篇 |
2000年 | 16篇 |
1999年 | 11篇 |
1998年 | 48篇 |
1997年 | 29篇 |
1996年 | 30篇 |
1995年 | 20篇 |
1994年 | 15篇 |
1993年 | 14篇 |
1992年 | 11篇 |
1991年 | 10篇 |
1990年 | 10篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 9篇 |
1984年 | 28篇 |
1983年 | 10篇 |
1982年 | 13篇 |
1981年 | 6篇 |
1980年 | 15篇 |
1979年 | 10篇 |
1978年 | 13篇 |
1977年 | 10篇 |
1976年 | 21篇 |
1975年 | 10篇 |
1972年 | 4篇 |
排序方式: 共有1546条查询结果,搜索用时 15 毫秒
1.
Bican Osman Bayça Salih Uğur Kuleyin Hamdi Gümrük Recep 《Metal Science and Heat Treatment》2021,63(3-4):156-162
Metal Science and Heat Treatment - The effect of solid boronizing at 950°C for 2 and 4 h on the phase composition, microstructure, hardness and abrasive wear of steel AISI 304L is studied... 相似文献
2.
3.
R. Murgan F. Razak D. R. Tilley T. Y. Tan J. Osman M. N. A. Halif 《Computational Materials Science》2004,30(3-4):468-473
We derive an expression for transmittivity (TSHG) of second harmonic generation (SHG) signals from a ferroelectric (FE) film. Intensities of up and down fields in the medium are investigated in relation to TSHG. The derivations are made based on undepletion of input fields and nonlinear wave equation derived from the Maxwell equations. We present two cases: film without mirrors and with partial mirrors. Expressions for the newly derived nonlinear susceptibility coefficients of SHG for real crystal symmetry [J. Opt. Soc. Am. B 19 (2002) 2007] are used to get more realistic results. Variations in TSHG with respect to film thickness are illustrated. 相似文献
4.
Maher M. Osman Mounir M. Abd El-Malek Aida B. Tadros Atef M. Michael 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,62(1):46-52
4-Amino-3-thio-1,24-triazolidine (L1) and 4-amino-5-thio-1,3,4-thiadiazole (LII) as well as their metal complexes of the general formulae MLI·2H2O and MLIICl (M; Pb(II), Cd(II) and Zn(II)) were prepared. With Sn(II), we obtained Sn(LI)2·2H2O and SnLIICl, respectively. The structures of the compounds were identified through elemental analysis, and IR and UV spectra measurements, in addition to thermal analysis in case of the metal complexes. The antifouling properties of the compounds were tested by their incorporation into paint formulations which were applied to PVC substrates and tested in water from Alexandria western harbour. When the compounds were added at 17·5% by volume, the coated panels were fouled after 3 months of immersion. The addition of 6·7% by volume of tributyltin oxide to 15·8% of the prepared compounds in one formulation elevated the paint efficiency and prevented fouling for 11 months. Paint containing solely tributyltin oxide at the same concentration was inactive against algae. 相似文献
5.
Anmar W. Sabri Zainab H. Ali Serwan F. Shawkat Lamia A. Thejar Thaer I. Kassim Khalid A. Rasheed 《河流研究与利用》1993,8(3):237-250
The influences of the Samarra impoundment on the ecology of the downstream sector of the river Tigris are investigated. Zooplankton were collected monthly from July 1987 to July 1988. It was found that zooplankton were most abundant during high river discharges in March. During the month of low river discharge, September, the zooplankton population was greatly reduced immediately below the barrage and remained so to the last downstream station. Several factors seem to explain such differences. The high discharge from the impoundment was found to be the dominating factor and may flush the small backwaters in which zooplankton were abundant, thus increasing the population in the river. Zooplankton species vary in their ability to sustain populations in the river, variations which are due mainly to species-specific characteristics. 相似文献
6.
Ibrahim H. Osman Nicos Christofides 《International Transactions in Operational Research》1994,1(3):317-336
The capacitated clustering problem (CCP) is the problem in which a given set of weighted objects is to be partitioned into clusters so that the total weight of objects in each cluster is less than a given value (cluster ‘capacity’). The objective is to minimize the total scatter of objects from the ‘centre’ of the cluster to which they have been allocated. A simple constructive heuristic, a R-interchange generation mechanism, a hybrid simulated annealing (SA) and tabu search (TS) algorithm which has computationally desirable features using a new non-monotonic cooling schedule, are developed. A classification of the existing SA cooling schedules is presented. The effects on the final solution quality of the initial solutions, the cooling schedule parameters and the neighbourhood search strategies are investigated. Computational results on randomly generated problems with size ranging from 50 to 100 customers indicate that the hybrid SA/TS algorithm out-performs previous simulated annealing algorithms, a simple tabu search and local descent algorithms. 相似文献
7.
W Graf M Dahlberg MM Osman L Holmberg L P?hlman B Glimelius 《Canadian Metallurgical Quarterly》1997,43(2):133-137
OBJECTIVE: The incidence of back pain in children in our country is unknown. Several causes can produce this symptom, but it is necessary to rule out pathologies that require specific treatments. The goal of this work was to study the incidence and the etiology of back pain in children in our country. PATIENTS AND METHODS: We present a prospective study done in our Orthopedic Department during a period of 7 months. Twenty-two patients were referred with back pain of at least two months duration. The incidence was 2.9% compared to the total number of patients. The average age ranged from 7 to 17 years. RESULTS: A careful history and a radiological examination diagnosed 50% (11 cases) of the causes of backache in the present study. An idiopathic etiology was the most frequent cause and represented 9 patients (41%). In the remaining 12 cases (59%) pathological causes that required special treatment were identified including 2 cases of Scheuermann disease, 4 cases of painful scoliosis, 3 spondylolysis with spondylolisthesis, 2 cases of discitis, 1 benign neoplasm and 1 psychogenic cause. CONCLUSIONS: We recommend conservative management with the use of medication for relief of pain and physical therapy in the idiopathic cases. In the remaining cases, the specific treatment of the disease can improve the back pain. 相似文献
8.
A three dimensional model of the BTA deep-hole machining system is presented by modelling each of the components separately and later combining to represent the total system. A model for the interaction between the workpiece and the cutting tool is also included. Such a model can determine the response of any component of the machine tool as well as the individual influence on the system performance. Based on this, physical models representing the three working methods in the BTA process can be studied, from which stochastic differential equations are derived to represent the resultant force system on the machine tool
A physical model for the stationary workpiece and rotating cutting tool working method is developed. The assumed modes method along with the Lagrange' equation is used to obtain the stochastic differential equation to represent the influence of axial force and torque, in order to obtain the response of the system under the action of the axial force and torque to predict the stability behaviour. 相似文献
A physical model for the stationary workpiece and rotating cutting tool working method is developed. The assumed modes method along with the Lagrange' equation is used to obtain the stochastic differential equation to represent the influence of axial force and torque, in order to obtain the response of the system under the action of the axial force and torque to predict the stability behaviour. 相似文献
9.
Erdem Bilgili zzet Cem Gknar Osman Nuri Ucan 《International Journal of Circuit Theory and Applications》2005,33(5):393-417
This paper presents a cellular neural network (CNN) scheme employing a new non‐linear activation function, called trapezoidal activation function (TAF). The new CNN structure can classify linearly non‐separable data points and realize Boolean operations (including eXclusive OR) by using only a single‐layer CNN. In order to simplify the stability analysis, a feedback matrix W is defined as a function of the feedback template A and 2D equations are converted to 1D equations. The stability conditions of CNN with TAF are investigated and a sufficient condition for the existence of a unique equilibrium and global asymptotic stability is derived. By processing several examples of synthetic images, the analytically derived stability condition is also confirmed. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
10.
Robinson J. Rubinov E. Toulson C. Prasada B. Sabri S. Goldberg N. Vonderweidt G. 《Communications, IEEE Transactions on》1991,39(11):1698-1708
The multimedia interactive conferencing application (MICA), a personal-workstation application for multipoint visual teleconferencing, is described. MICA allows people at two or more locations to share visual material such as documents, photographs, and computer screens in a highly interactive way. It supports the distribution, storage, retrieval, and high-quality display of visuals, real-time interaction by pointing and annotation, and meeting services facilities. The context of multimedia teleconferencing and computer-supported cooperative work is established, relating earlier research to the design of MICA. The services MICA offers are outlined. The handling, compression, and display of multiple media, and the design of a suitable user interface for MICA are discussed 相似文献