全文获取类型
收费全文 | 2812篇 |
免费 | 181篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 37篇 |
化学工业 | 785篇 |
金属工艺 | 50篇 |
机械仪表 | 130篇 |
建筑科学 | 128篇 |
矿业工程 | 8篇 |
能源动力 | 106篇 |
轻工业 | 443篇 |
水利工程 | 17篇 |
石油天然气 | 11篇 |
无线电 | 191篇 |
一般工业技术 | 370篇 |
冶金工业 | 112篇 |
原子能技术 | 11篇 |
自动化技术 | 595篇 |
出版年
2024年 | 11篇 |
2023年 | 37篇 |
2022年 | 74篇 |
2021年 | 150篇 |
2020年 | 112篇 |
2019年 | 132篇 |
2018年 | 110篇 |
2017年 | 115篇 |
2016年 | 125篇 |
2015年 | 98篇 |
2014年 | 142篇 |
2013年 | 244篇 |
2012年 | 179篇 |
2011年 | 216篇 |
2010年 | 174篇 |
2009年 | 160篇 |
2008年 | 124篇 |
2007年 | 125篇 |
2006年 | 109篇 |
2005年 | 79篇 |
2004年 | 63篇 |
2003年 | 53篇 |
2002年 | 54篇 |
2001年 | 32篇 |
2000年 | 33篇 |
1999年 | 26篇 |
1998年 | 25篇 |
1997年 | 26篇 |
1996年 | 21篇 |
1995年 | 18篇 |
1994年 | 15篇 |
1993年 | 16篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 13篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1970年 | 2篇 |
1968年 | 1篇 |
排序方式: 共有2994条查询结果,搜索用时 15 毫秒
1.
Eduardo Freire Teodiano Bastos-Filho Mário Sarcinelli-Filho Ricardo Carelli 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2004,34(1):419-429
This paper proposes an alternative approach to address the problem of coordinating behaviors in mobile robot navigation: fusion of control signals. Such approach is based on a set of two decentralized information filters, which accomplish the data fusion involved. Besides these two fusion engines, control architectures designed according to this approach also embed a set of different controllers that generate reference signals for the robot linear and angular speeds. Such signals are delivered to the two decentralized information filters, which estimate suitable overall reference signals for the robot linear and angular speeds, respectively. Thus, the background for designing such control architectures is provided by the nonlinear systems theory, which makes this approach different from any other yet proposed. This background also allows checking control architectures designed according to the proposed approach for stability. Such analysis is carried out in the paper, and shows that the robot always reaches its final destination, in spite of either obstacles along its path or the environment layout. As an example, a control architecture is designed to guide a mobile robot in an experiment, whose results allows checking the good performance of the control architecture and validating the design approach proposed as well. 相似文献
2.
The present paper studies a feedback regulation problem that arises in at least two different biological applications. The feedback regulation problem under consideration may be interpreted as an adaptive control problem for tuning bifurcation parameters, and it has not been studied in the control literature. The goal of the paper is to formulate this problem and to present some preliminary results. 相似文献
3.
César I. Beristain Ebner Azuara Hugo S. Garcia & Eduardo J. Vernon-Carter 《International Journal of Food Science & Technology》1996,31(5):379-386
The water and oil uptake of mesquite and arabic gums in powdered form was studied at temperatures of 23, 35 and 45°C. A previously proposed equation to predict osmotic equilibrium was tested using the experimental data with both gums and a good statistical fit was obtained. Mesquite gum showed the highest water and oil absorption at all temperatures studied. Temperature dependence of the reciprocal of the S1 and WL∞ were determined using an Arrhenius equation. The activation energy for water and oil absorption for gum arabic was 21.98 and 39.57 kJ mol−1 , compared to that of mesquite gum having values of 15.79 and 46.16 kJ mol−1 , respectively. A second order kinetic model was obtained for water and oil absorption for both gums. 相似文献
4.
Michael Sonis Geoffrey J. D. Hewings Eduardo Haddad 《The Annals of Regional Science》1996,30(4):391-408
The effects of structural change in all sectors of some regions in multiregional input-output systems are explored in this paper. For each region, the changes in direct inputs are decomposed into a matrix of intraregional changes and a matrix of interregional backward linkage changes. This distinction provides for a decomposition of changes in the Leontief inverse into a sum of matrices representing the matrices of intraregional and interregional fields of influence of changes. In turn, this process facilitates the identification of changes in gross outputs that may be traced to changes in intra- and interregional structural changes. The analysis is applied to the European input-output tables for 1975 and 1985.This paper was presented at the 1996 annual meeting of the Western Regional Science Association 相似文献
5.
A spatially resolved infrared (IR) imaging technique to monitor the linear adsorbed CO coverage on supported catalyst surface combining an IR bandpass filter and an IR thermography camera has been developed. Images acquired during the CO adsorption/desorption and ignition indicate that the technique provides an excellent method to image the change of surface coverage with a spatial resolution. It is expected that the combination of infrared thermography with spatially resolved imaging of surface coverage will provide a deeper insight in the dynamics of spatio-temporal patterns on heterogeneous catalysts. 相似文献
6.
Eduardo D. Sontag 《Systems & Control Letters》1987,9(5):361-367
Explicit equations are given for the moduli space of framed instantons as a quasi-affine variety, based on the representation theory of noncommutative power series, or equivalently, the minimal realization theory of bilinear systems. 相似文献
7.
JR Henkel G Apodaca Y Altschuler S Hardy OA Weisz 《Canadian Metallurgical Quarterly》1998,9(9):2477-2490
The function of acidification along the endocytic pathway is not well understood, in part because the perturbants used to modify compartmental pH have global effects and in some cases alter cytoplasmic pH. We have used a new approach to study the effect of pH perturbation on postendocytic traffic in polarized Madin-Darby canine kidney (MDCK) cells. Influenza M2 is a small membrane protein that functions as an acid-activated ion channel and can elevate the pH of the trans-Golgi network and endosomes. We used recombinant adenoviruses to express the M2 protein of influenza virus in polarized MDCK cells stably transfected with the polymeric immunoglobulin (Ig) receptor. Using indirect immunofluorescence and immunoelectron microscopy, M2 was found to be concentrated at the apical plasma membrane and in subapical vesicles; intracellular M2 colocalized partly with internalized IgA in apical recycling endosomes as well as with the trans-Golgi network marker TGN-38. Expression of M2 slowed the rate of IgA transcytosis across polarized MDCK monolayers. The delay in transport occurred after IgA reached the apical recycling endosome, consistent with the localization of intracellular M2. Apical recycling of IgA was also slowed in the presence of M2, whereas basolateral recycling of transferrin and degradation of IgA were unaffected. By contrast, ammonium chloride affected both apical IgA and basolateral transferrin release. Together, our data suggest that M2 expression selectively perturbs acidification in compartments involved in apical delivery without disrupting other postendocytic transport steps. 相似文献
8.
9.
Miguel Eduardo L. Felismino Paul A. Helm Chelsea M. Rochman 《Journal of Great Lakes research》2021,47(1):180-189
Microplastics (plastic particles <5 mm in size) have been reported in ecosystems worldwide and have been shown to cause adverse negative impacts on organisms. This study provides the first report of microplastics and other anthropogenic microparticles in the surface waters and sediments of Lake Simcoe in Ontario, Canada, a popular recreational and fishing lake. Surface waters (low volume grabs and manta trawls) and sediments were sampled from eight sites to determine microparticle abundances and character (size, morphology, material identity). Concentrations ranged from 0 to 0.7 particles/L in surface water grab samples, 0.4–1.3 particles/m3 in manta trawl samples, and 8.3–1070 particles/kg in sediment samples. Spectroscopic analysis confirmed that 72% of particles were anthropogenic, with 64% unambiguously identified as microplastics. However, confirmed microplastic concentrations were approximately 6–7 times lower than unadjusted counts in sediments, demonstrating the importance of verifying and adjusting reported values. Fibers were only quantified and characterized in surface water grab samples and sediments, and were the most common morphology, accounting for 82% and 89% of anthropogenic particles, respectively. Fragments were most common in manta trawl samples (75%, excluding fibers) and consisted predominantly of polyethylene (41%) and polypropylene (22%). The influence of proximity to urban centers and prevailing winds on the distribution of microplastics was apparent in surface water manta trawls. Microplastics and other anthropogenic microparticles are present in Lake Simcoe but at lower abundances than at locations impacted by larger population centers in other large freshwater lakes such as Lakes Ontario and Erie of the Great Lakes. 相似文献
10.
A fuzzy queue-aware routing approach for wireless mesh networks 总被引:1,自引:0,他引:1
Billy Pinheiro Vagner Nascimento Rafael Lopes Eduardo Cerqueira Antonio Abelem 《Multimedia Tools and Applications》2012,61(3):747-768
Recent advances in Wireless Mesh Networks (WMNs) have overcome the drawbacks of traditional wired and ad-hoc networks and now they are seen as a means of allowing last mile communications with quality level assurance in Future Multimedia Systems. However, new routing schemes are needed to provide end-to-end Quality of Service (QoS) and Quality of Experience (QoE) support for delay/loss/jitter-sensitive multimedia applications. The well-known OLSR (Optimized Link State Routing) protocol with ETX (Expected Transmission Count) metric brings many benefits to the path selection process, but has a drawback with regard to queue availability management, which reduces the system performance. This problem is caused when OLSR-EXT control messages are exchanged and the queues of mesh routers along the end-to-end communication path are overloaded. As a result, multimedia-related packets will suffer from loss/delay/jitter and the overall system performance will decrease. This paper proposes the Optimized Link State Routing-Fuzzy ETX Queue (OLSR-FEQ) protocol to overcome the limitations of OLSR-ETX regarding queue availability, QoS and QoE assurance. OLSR-FEQ optimizes network and user-based parameters by coordinating queue availability, QoS and fuzzy issues in the routing decision process as a way of allocating the best paths for multimedia applications. Performance evaluations were carried out with the Network Simulator (NS-2.34) to show the benefits of the proposed solution when compared with existing routing schemes, namely OLSR-ETX, OLSR-FLC, OLSR-MD and HWMP (IEEE 802.11s standard), regarding QoS (unsuccessful packet delivery and throughput) and QoE (PSNR, SSIM, VQM and MOS) parameters. 相似文献