全文获取类型
收费全文 | 1157篇 |
免费 | 48篇 |
专业分类
电工技术 | 16篇 |
综合类 | 4篇 |
化学工业 | 501篇 |
金属工艺 | 83篇 |
机械仪表 | 35篇 |
建筑科学 | 19篇 |
矿业工程 | 3篇 |
能源动力 | 45篇 |
轻工业 | 28篇 |
水利工程 | 2篇 |
石油天然气 | 7篇 |
无线电 | 40篇 |
一般工业技术 | 272篇 |
冶金工业 | 15篇 |
原子能技术 | 9篇 |
自动化技术 | 126篇 |
出版年
2024年 | 3篇 |
2023年 | 27篇 |
2022年 | 7篇 |
2021年 | 21篇 |
2020年 | 17篇 |
2019年 | 24篇 |
2018年 | 23篇 |
2017年 | 52篇 |
2016年 | 79篇 |
2015年 | 72篇 |
2014年 | 75篇 |
2013年 | 153篇 |
2012年 | 84篇 |
2011年 | 90篇 |
2010年 | 83篇 |
2009年 | 91篇 |
2008年 | 38篇 |
2007年 | 63篇 |
2006年 | 28篇 |
2005年 | 23篇 |
2004年 | 9篇 |
2003年 | 14篇 |
2002年 | 21篇 |
2001年 | 22篇 |
2000年 | 14篇 |
1999年 | 8篇 |
1998年 | 10篇 |
1997年 | 10篇 |
1996年 | 10篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有1205条查询结果,搜索用时 15 毫秒
1.
Effects of ferrite materials as supports (CoFe2O4, NiFe2O4, and Fe3O4) on nano-TiO2 were elucidated by their use in the oxidation of methylene blue. These photocatalysts, which were synthesized by co-precipitation, were characterized by XRD, SEM, EDS and VSM. The crystalline phase of TiO2 onto magnetic MFe2O4 was formed by anatase and rutile. TiO2/CoFe2O4 exhibited the strongest magnetic property of the prepared catalysts, and the photocatalytic efficiencies followed the order TiO2/CoFe2O4 > TiO2/NiFe2O4 > TiO2/Fe3O4. MB decolorization was enhanced with the amount of TiO2 on the photocatalyst, and was moderately affected by the extent of structural distortion of ferrite supports. 相似文献
2.
《Journal of the European Ceramic Society》2020,40(4):1111-1118
Highly textured TiB2 ceramics were prepared by slip casting an aqueous suspension in a magnetic field of 9 T, followed by sintering using Field Assisted Sintering Technology (FAST). Particle size refinement by ball milling improved both the degree of texturing and densification of the material (RD > 98 %). The sintered material exhibited a Lotgering orientation factor of 0.90, with the c-axis of TiB2 oriented parallel to the magnetic field and FAST pressing direction. The texturing effect induced by the uniaxial pressing was negligible. The textured TiB2 material exhibited a significant anisotropy in mechanical properties; the values of hardness and indentation elastic modulus measured along directions transverse to the c-axis of TiB2 were 37 % and 13 % higher than the ones measured along the c-axis direction. Moreover, the specific wear rate of a surface of textured TiB2 parallel to the field was one order of magnitude lower than a surface perpendicular to the field. 相似文献
3.
A current conveyor based rectifier circuit with very low temperature sensitivity is presented. The use of a current mirror arrangement to bias the rectifying diodes provides higher temperature stability than previously reported designs. The output offset voltage is easily adjustable to the desired optimum level 相似文献
4.
Camelia Betianu Florentina A Caliman Maria Gavrilescu Igor Cretescu Corneliu Cojocaru Ioannis Poulios 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(11):1454-1465
BACKGROUND: Heterogeneous photocatalysis is influenced by a number of parameters involving synergistic effects; hence, an experimental strategy design that considers interactions between the main variables is needed. The response surface methodology was applied for the investigation of photodegradation of 20 mg L?1 Orange II in aqueous solutions and for optimization of color removal efficiency. Preliminary studies were performed to identify the parameters to be selected for optimization. RESULTS: The input variables considered for experimental design were: solution initial pH, oxidizing agent (H2O2) initial concentration and UV‐A irradiation time. The multivariate experimental design allowed the development of a quadratic response surface model to be used for the prediction of color removal efficiency over the full range of the experimental region. Under the optimum conditions established in the region of experimentation (pH = 6.9, [H2O2]0 = 183 mg L?1 and t = 32 min), a 100% color removal efficiency was obtained in experiments. CONCLUSIONS: It was found that the variables considered have important effects on color removal efficiency. The results demonstrate that the use of experimental design strategy is indispensable for successful investigation and adequate modeling of the process because the interdependence of the reaction parameters cannot be neglected. Copyright © 2008 Society of Chemical Industry 相似文献
5.
The latest data concerning the modification of polymers containing phenylquinoxaline cycles and the manufacture of polymer materials on their basis are systematized. It has been shown that the design of silicon-and fluorine-containing and sulfated poly(phenylquinoxalines) makes it possible to significantly improve the processability of polymers and the performance characteristics of the related materials. 相似文献
6.
Popa Iolanda V. Burlacu Alexandru Gavrilescu Otilia Dranga Mihaela Prelipcean Cristina Cijevschi Mihai Cătălina 《Neural computing & applications》2021,33(21):14133-14146
Neural Computing and Applications - Colonoscopy is the “gold” standard for evaluating disease activity in ulcerative colitis (UC). An important area of research is finding a... 相似文献
7.
P2P based live streaming has been gaining popularity. The new generation P2P live streaming systems not only attract a large number of viewers, but also support better video quality by streaming the content at higher bit-rate. In this paper, we propose a novel P2P streaming framework, called Hierarchically Clustered P2P Video Streaming, or HCPS, that can support the streaming rate approaching the optimal upper bound while accommodating large viewer population. The scalability comes with the hierarchical overlay architecture by grouping peers into clusters and forming a hierarchy among them. Peers are assigned to appropriate cluster so as to balance the bandwidth resources across clusters and maximize the supportable streaming rate. Furthermore, individual peers perform distributed queue-based scheduling algorithms to determine how to retrieve data chunks from source and neighboring peers, and how to utilize its uplink bandwidth to serve data chunks to other peers. We show that queue-based scheduling algorithms allow to fully utilize peers’ uplink bandwidths, and HCPS supports the streaming rate close to the optimum in practical network environment. The prototype of HCPS is implemented and various design issues/tradeoffs are investigated. Experiments over the PlanetLab further demonstrate the effectiveness of HCPS design. 相似文献
8.
Adrian Burlacu Cosmin Copot Corneliu Lazar 《Journal of Intelligent Manufacturing》2014,25(5):1125-1134
This paper presents a real-time architecture for visual servoing of robot manipulators using nonlinear based predictive control. In order to increase the robustness of the control algorithm, image moments were chosen to be the visual features which describe the objects from the image. A visual predictive architecture is designed to solve tasks addressed to robot manipulators with an eye-in-hand configuration. An implementation of the proposed architecture is done so that the capabilities of a 6 d.o.f robot manipulator are extended. The results of different experiments conducted with two types of image moments based controllers (proportional and predictive with reference trajectory) are presented and discussed. 相似文献
9.
Marioara Onciu 《应用聚合物科学杂志》2007,103(3):2013-2020
A series of new aromatic polyamides containing cinnamide pendent units were prepared from 2′‐(cinnamide)ethyl‐3,5‐diaminobenzoate and various aromatic dicarboxylic acids by the direct polycondensation reaction, with triphenyl phosphite and pyridine as condensing agents. The polyamides were characterized by 1H NMR, IR, and UV spectroscopy, and gel permeation chromatography. Their thermal stability was studied by thermogravimetric analysis in air, and differential scanning calorimetry. These polymers were readily soluble in polar aprotic solvents and can be cast from their solutions in flexible and tough films. Glass transition temperatures (Tgs) of these polyamides were observed in the range of 225–245°C. Their inherent viscosities varied from 0.77 to 1.12 dL/g that corresponded to weight–average and number–average molecular weights of 39,000–72,700 and 18,800–29,000, respectively. These polymers can be photochemically crosslinked. The photochemical aspects were revealed by means of UV–vis and IR analyses onto thin films. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2013–2020, 2007 相似文献
10.
Controllability of positive systems by positive inputs arises naturally in applications where both external and internal variables must remain positive for all time. In many applications, particularly in population biology, the need for positive inputs is often overly restrictive. Relaxing this requirement, the notion of positive state controllability of positive systems is introduced. A connection between positive state controllability and positive input controllability of a related system is established and used to obtain Kalman-like controllability criteria. In doing so we aim to encourage further study in this underdeveloped area. 相似文献