全文获取类型
收费全文 | 294篇 |
免费 | 7篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 2篇 |
综合类 | 1篇 |
化学工业 | 49篇 |
金属工艺 | 8篇 |
机械仪表 | 4篇 |
建筑科学 | 7篇 |
能源动力 | 9篇 |
轻工业 | 35篇 |
水利工程 | 2篇 |
无线电 | 52篇 |
一般工业技术 | 56篇 |
冶金工业 | 10篇 |
自动化技术 | 71篇 |
出版年
2022年 | 13篇 |
2021年 | 16篇 |
2020年 | 8篇 |
2019年 | 11篇 |
2018年 | 18篇 |
2017年 | 14篇 |
2016年 | 14篇 |
2015年 | 13篇 |
2014年 | 10篇 |
2013年 | 23篇 |
2012年 | 16篇 |
2011年 | 18篇 |
2010年 | 11篇 |
2009年 | 14篇 |
2008年 | 12篇 |
2007年 | 7篇 |
2006年 | 11篇 |
2005年 | 12篇 |
2004年 | 7篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 10篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 8篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有306条查询结果,搜索用时 15 毫秒
91.
Water Resources Management - This article examines the potential legal implications of the adoption and implementation of transboundary water agreements and international water conventions as a... 相似文献
92.
Maryam Sharifi-Sanjani Mariah Berman Dmitry Goncharov Mohammad Alhamaydeh Theodore Guy Avolio Jeffrey Baust Baojun Chang Ahasanul Kobir Mark Ross Claudette St. Croix Seyed Mehdi Nouraie Charles F. McTiernan Christine S. Moravec Elena Goncharova Imad Al Ghouleh 《International journal of molecular sciences》2021,22(11)
93.
Hai Liu Xiaohua Jia Peng-Jun Wan Chih-Wei Yi Makki S.K. Pissinou N. 《Networking, IEEE/ACM Transactions on》2007,15(2):334-345
This paper addresses the maximal lifetime scheduling problem in sensor surveillance systems. Given a set of sensors and targets in an area, a sensor can watch only one target at a time, our task is to schedule sensors to watch targets and forward the sensed data to the base station, such that the lifetime of the surveillance system is maximized, where the lifetime is the duration that all targets are watched and all active sensors are connected to the base station. We propose an optimal solution to find the target-watching schedule for sensors that achieves the maximal lifetime. Our solution consists of three steps: 1) computing the maximal lifetime of the surveillance system and a workload matrix by using the linear programming technique; 2) decomposing the workload matrix into a sequence of schedule matrices that can achieve the maximal lifetime; and 3) determining the sensor surveillance trees based on the above obtained schedule matrices, which specify the active sensors and the routes to pass sensed data to the base station. This is the first time in the literature that the problem of maximizing lifetime of sensor surveillance systems has been formulated and the optimal solution has been found 相似文献
94.
Makki Abdelmouleh Sami Boufi Mohamed Naceur Belgacem Alain Dufresne Alessandro Gandini 《应用聚合物科学杂志》2005,98(3):974-984
Unsaturated polyester and epoxy resin matrices were filled with silane‐treated cellulose fibers and the ensuing composites were tested in terms of mechanical properties before and after accelerated aging consisting of their immersion into water. The coupling agents used were γ‐aminopropyltriethoxysilane (APS), γ‐methacrylopropyltrimethoxysilane (MPS), hexadecytrimethoxysilane, and γ‐mercaptopropyltrimethoxysilane (MRPS) and those containing reactive functions capable of reacting at one end with the fibers and at the other with the matrix, namely, APS, MPS, and MRPS, were more efficient in improving the mechanical properties of the composites. The immersion into water induced a drastic loss of mechanical properties of the materials. The water uptake of the composites was also studied and showed that the silane treatment was poorly efficient in preventing cellulose from water absorption. The fracture surfaces were inspected by scanning electron microscopy, which confirmed the quality of the interface. These observations were in agreement with the results obtained from the dynamic mechanical characterization. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 974–984, 2005 相似文献
95.
This work describes the principle of protecting polyunsaturated fatty acids by holding them in the low moisture/solid/glassy-state starch matrix. One strategy already employed commercially is to encapsulate oil droplets within a solid wall that is highly impermeable to oxygen. These microencapsulated powders can then be added to foods. A shorter route would be to add PUFA-rich oils directly into a food formulation during the processing of a low moisture product. This should effectively encapsulate the valuable oils and protect them from oxidation. ω-6 Linoleic acid was incorporated into a waxy maize starch matrix via extrusion cooking. Linoleic acid oxidation occurred when this model food system was held in both the glassy and rubbery states (0.3 and 0.95 Aw, respectively) at 50 °C. The initial oxidation, not surprisingly, occurs near the surface, but interestingly the highest initial rate of lipid oxidation occurred, not in the rubbery samples, but in glassy state starch extrudates with surface micro-cracks. 相似文献
96.
Makki Kia Dell John Pissinou Niki Moh W. Melody Jia Xiaohua 《The Journal of supercomputing》2000,16(1-2):117-132
In this paper, we investigate distributed mutual exclusion algorithms and delineate the features of a new distributed mutual exclusion algorithm. The basis of the algorithm is the logical ring structure employed in token-based mutual exclusion algorithms. Specifically, there exists dynamic properties of the logical ring that, given certain restrictions regarding message traffic flow, passively give useful information about the location of the token. Effectively, the algorithm demonstrates a type of intelligent routing that identifies useful shortcuts in the routing of the token. The result is a reduction in the total number of messages exchanged prior to the execution of the critical section as compared to the algorithm proposed by Fu and Tzeng [3]. Furthermore, the algorithm allows for an increased degree of fairness in a lightly loaded system than that allowed by Fu and Tzeng's algorithm. The paper also addresses failure recovery issues. 相似文献
97.
Electrical properties and longitudinal modulus of superconductor/polymer NdBa2Cu3O7−δ/PVC composites
High temperature superconductor NdBa2Cu3O7–/poly(vinyl chloride) (Nd123/PVC) composites have been prepared by cold press and hot press methods. Addition of PVC resulted in increase of the electrical resistivity with percolation occurring between 0.3 and 0.5 Nd123 volume fraction for both preparation methods. Although the samples showed some form of magnetic levitation at liquid nitrogen temperature, they do not show any zero-resistance temperature indicating the lack of effective superconducting percolative path. The density deviates from the linear calculated value with increasing Nd123 content at 0.3 volume fraction for the cold press and at 0.6 for the hot pressed samples due to increasing porosity. X-ray powder diffraction patterns suggest that the Nd123 crystals tend to align when the composites are prepared by hot press method. A resistance anomaly is observed at 90 K in the hot press composites indicating improved electrical contact between the aligned Nd123 grains. The longitudinal modulus increases as Nd123 content is increased. 相似文献
98.
We propose an extension of the classical CSMA/CD protocol that eliminates its three main drawbacks. The new protocol, called dual‐mode CSMA/CD (CSMA/DM), operates in two modes, light mode and heavy mode. The light mode of CSMA/DM is almost the same as the original CSMA/CD protocol and is primarily used when the LAN load is light. The heavy mode is a collision free mode and is applied when the LAN load is heavy. The proposed modification to CSMA/CD is minimal while performance gain is significant. CSMA/DM automatically switches between its two modes based on the observed LAN load. Under heavy mode, the monitor station in a CSMA/DM LAN allocates bandwidth to those busy stations without collisions. The newly added priority scheme in the heavy mode allows stations to reserve bandwidth for their high priority frames. Compared with the current collision‐free fast Ethernet and Gigabit Ethernet, CSMA/DM has the advantage of not needing any extra switches or hubs while maintaining comparable performance. Its priority scheme provides more flexibility on bandwidth distribution than in fast Ethernet and Gigabit Ethernet. It can also be easily adapted for high‐speed wireless LANs. More importantly, CSMA/DM should be a good alternative of the widely used CSMA/CA (collision avoidance) in mobile ad hoc networks (MANET) and sensor networks. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
99.
A graded-reflectivity-mirror (GRM) unstable resonator with low output coupling is described, where a custom-made optical phase element is used inside the resonator to provide maximally flat output. The phase element removes the dip in the output beam by pre-compensating the internal Gaussian mode. An experiment is performed with a flashlamp-pumped Nd:YAG laser. The resonator's magnification (M) and the GRM's central reflectivity (R0) are 2.3 and 0.7, respectively. The large dip in the center of the output is removed using the custom-made phase element. This resonator has the advantage over a conventional GRM unstable resonator of being suitable for lower-gain laser media. The gain required to overcome fundamental mode cavity losses for maximally flat output is decreased from 22.3 (for a conventional GRM resonator) to 4.3 (for the resonator containing the phase element). This reduction in required gain comes with essentially no loss to the resonator modal discrimination 相似文献
100.
One of the problems encountered in the nondestructive testing of pavements with ground penetrating radar (GPR) is the detection of multiple-layer reflections within the GPR return. Detecting reflections is especially problematic when the pavement layers are thin with respect to the probing pulse width, in which case overlapping between the reflected pulses occurs, causing the weak reflections to be masked by the stronger reflections in their vicinity. In this study, the problem is solved by iteratively detecting the strong reflections present within the GPR signal using either a threshold or a matched filter detector. The detected pulses are then used in a reflection model to synthesize a signal “similar” to the measured GPR signal in the least-squares sense. The synthesized signal is then subtracted from the measured signal to reveal the masked weak reflections, which are later detected iteratively using the same method. This technique was successfully applied to field GPR data collected from an experimental pavement site: the Virginia Smart Road. 相似文献