全文获取类型
收费全文 | 891篇 |
免费 | 50篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 12篇 |
综合类 | 1篇 |
化学工业 | 236篇 |
金属工艺 | 22篇 |
机械仪表 | 23篇 |
建筑科学 | 14篇 |
矿业工程 | 2篇 |
能源动力 | 73篇 |
轻工业 | 45篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 79篇 |
一般工业技术 | 191篇 |
冶金工业 | 30篇 |
原子能技术 | 2篇 |
自动化技术 | 214篇 |
出版年
2024年 | 9篇 |
2023年 | 44篇 |
2022年 | 47篇 |
2021年 | 72篇 |
2020年 | 48篇 |
2019年 | 53篇 |
2018年 | 70篇 |
2017年 | 51篇 |
2016年 | 43篇 |
2015年 | 27篇 |
2014年 | 37篇 |
2013年 | 69篇 |
2012年 | 47篇 |
2011年 | 58篇 |
2010年 | 50篇 |
2009年 | 44篇 |
2008年 | 39篇 |
2007年 | 36篇 |
2006年 | 32篇 |
2005年 | 20篇 |
2004年 | 10篇 |
2003年 | 7篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 3篇 |
排序方式: 共有947条查询结果,搜索用时 15 毫秒
91.
92.
Micron- to nanometer-sized ultrasound agents, like encapsulated microbubbles and echogenic liposomes, are being developed for diagnostic imaging and ultrasound mediated drug/gene delivery. This review provides an overview of the current state of the art of the mathematical models of the acoustic behavior of ultrasound contrast microbubbles. We also present a review of the in vitro experimental characterization of the acoustic properties of microbubble based contrast agents undertaken in our laboratory. The hierarchical two-pronged approach of modeling contrast agents we developed is demonstrated for a lipid coated (Sonazoid $^\mathrm{TM})$ and a polymer shelled (poly D-L-lactic acid) contrast microbubbles. The acoustic and drug release properties of the newly developed echogenic liposomes are discussed for their use as simultaneous imaging and drug/gene delivery agents. Although echogenicity is conclusively demonstrated in experiments, its physical mechanisms remain uncertain. Addressing questions raised here will accelerate further development and eventual clinical approval of these novel technologies. 相似文献
93.
94.
Carbon electrodes coupled with electrochemical detection have been used extensively for the investigation of biogenic amines. Herein we report the fabrication and characterization of carbonaceous electrodes prepared from pyrolyzed parylene C (PPC) films. High-aspect ratio carbonaceous microelectrodes have been prepared by masking PPC coated pipets with an insulating parylene C film. PPC thin film electrodes were characterized electrochemically, spectroscopically, and with electron microscopy. The procedures described here offer a route to fabrication of thin film carbon electrodes that can be patterned and produced in parallel. These electrodes are similar to carbon electrodes derived from pyrolyzed photoresist films but do not require spin-coating or lithography and can readily coat three-dimensional surfaces. 相似文献
95.
Efstratios N. Pistikopoulos Yuhe Tian Rahul Bindlish 《American Institute of Chemical Engineers》2021,67(5):e17204
In this article, the importance of considering operability and control criteria in the analysis and design of intensified and modular processes is discussed. We first analyze the impact on operability of key factors including: (i) degrees of freedom, (ii) process constraints, (iii) numbering up vs. scaling up, and (iv) dynamic/periodic operation. Comparative examples are presented to showcase the pros and cons in intensified/modular systems vs. their conventional counterparts from operability and control aspects. Then we look into metrics and tools to address these challenges such as: (i) flexibility analysis, (ii) operability-based design, and (iii) advanced model-based control. Considering different conceptual design stages as synthesis intensification, steady-state design, and dynamic operational optimization, we highlight the need to incorporate different levels of operability considerations. Future research opportunities and perspectives are also identified, particularly emphasizing the importance of a holistic strategy for integrated design, operability, and control of intensified and modular process systems. 相似文献
96.
Rahul Kala 《Advanced Robotics》2013,27(14):1113-1122
Rapidly exploring random trees (RRT) and probabilistic roadmaps (PRM) are sampling-based techniques being extensively used for robot path planning. In this paper, the tree structure of the RRT is generalized to a graph structure which enables a greater exploration. Exploration takes place simultaneously from multiple points in the map, all explorations fusing at multiple points producing well-connected graph architecture. Initially, in a typical RRT manner, the search algorithm attempts to reach the goal by expansions, and thereafter furtherer areas are explored. With some additional computation cost, as compared to RRT with a single robot, the results can be significantly improved. The so-formed graph is similar to roadmap produced by PRM. However as compared to PRM, the proposed algorithm has a more judicious search strategy and is adaptable to the number of nodes as a parameter. Experimental results are shown with multiple robots planned using prioritization scheme. Results show the betterment of the proposed algorithm as compared to RRT and PRM techniques. 相似文献
97.
S. Rahul Neson Varghese K. Vinod K.M. Devadas Syju Thomas P. Anees M.K. Chattopadhyay S.B. Roy U. Syamaprasad 《Materials Research Bulletin》2011,46(11):2036-2040
MgB2 bulk samples added with nano SiO2 and/or nano diamond were prepared by powder-in-sealed-tube (PIST) method and the effects of addition on structural and superconducting properties were studied. X-ray diffraction (XRD) analysis revealed that the addition caused systematic reduction in ‘a’ lattice parameter due to the substitution of C atoms at B sites and the strain caused by reacted intragrain nano particles of Mg2Si as evinced by transmission electron microscope image. Scanning electron microscopy images showed distinct microstructural variations with SiO2/diamond addition. It was evident from DC magnetization measurements that the in-field critical current density [JC(H)] of doped samples did not fall drastically like the undoped sample. Among the doped samples the JC(H) of co-doped samples were significantly higher and the best co-doped sample yielded a JC, an order of magnitude more than the undoped one at 5 K and 8 T. 相似文献
98.
Ranjit Prasad Vanja Pasanovic‐Zujo Rahul K. Gupta Ferenc Cser Sati N. Bhattacharya 《Polymer Engineering and Science》2004,44(7):1220-1230
Shear and extensional rheological measurements were conducted in conjunction with laser light scattering (LLS) on ethylene‐vinyl acetate copolymer (EVA) nanocomposites. The materials were prepared by melt‐mixing EVA and commercially acquired layered silicates. Wide Angle X‐Ray Scattering (WAXS) was used to ascertain the degree of layer swelling. This could be attributed to the intercalation of polymer chains into the interlayer of the silicates. The nanocomposites prepared were determined to be predominantly intercalated in nature. In shear rheological tests, the nanocomposites exhibited an increase in viscoelastic properties compared to the pure EVA. The extent of this property enhancement was not as pronounced as had been reported in many instances with respect to other polymer nanocomposites. This could be attributed to the absence of a network structure normally observed in an exfoliated system. The extensional rheological tests showed an increase in extensional flow properties. This was confirmed by the LLS, which indicated that the filled systems had higher deformability than the unfilled one. Polym. Eng. Sci. 44:1220–1230, 2004. © 2004 Society of Plastics Engineers. 相似文献
99.
On the Consequences of Information Delays in the Scheduling of Semi-Automated Flexible Machines 总被引:3,自引:1,他引:2
Rahul Caprihan Subhash Wadhwa Satish Kumar 《International Journal of Flexible Manufacturing Systems》2004,16(3):251-275
Manufacturing systems with varying levels and types of flexibility employ alternative scheduling strategies to exploit flexibility
for performance enhancement. Scheduling decisions in manufacturing systems are influenced by time delays due to information
handling activities such as information collection, transfer, and processing. More specifically, scheduling strategies implicitly
involve information intensive activities that may entail significant time delays for implementation, depending on the extant
shop floor automation and integration within a flexible system. These are information delays and we believe that most contemporary
flexible systems must inherently cope with some level of information delay when implementing on-line scheduling strategies.
This paper conceptualizes the manifestation of information delays in the context of scheduling decisions within flexible systems
through the definition of three key delay modes: (i) Mode 1 information-transfer delay; (ii) Mode 2 decision-implementation
delay; and (iii) Mode 3 status-review delay. We then stress the need and importance of devising suitable on-line scheduling
strategies for countering the effect of information delays by demonstrating the efficacy of a novel scheduling strategy on
a single machine. While opening a new scheduling dimension with potential research ramifications, this paper highlights the
fact that the concept of information delay can effectively capture the synergism issues related with flexibility, integration,
and automation in the context of scheduling decisions within semi-automated flexible systems. 相似文献
100.
Rahul Banik Dong-Yeon Lee Dae-Gab Gweon 《Journal of Mechanical Science and Technology》2005,19(12):2197-2204
The combination of Gas chromatography (GC) for separation and Flame Ionization Detection (FID) for detection and identification of the components of a mixture of compounds is a fast and strongly proved method of analytic chemistry. The objective of this research was to design a combined High-speed miniature screening Gas chromatograph along with a Flame Ionization Detector for quick, quantitative and qualitative analysis of gas components. This combined GC-FID system is suitable to detect the volatile and semi-volatile hydrocarbons present in a gas mixture. The construction made it less expensive, easy to use and movable. The complete gas path was developed. On/off valves, temperature and flow sensors and their interface electronics were used for controlling purpose. A Microcontroller was programmed to measure the temperature and gas flow using the sensors and to control and regulate them using the electronics and valves. A pocket PC with its touch screen served as a user interface for the system. Software was developed for the pocket PC, which makes the communication possible with the Microcontroller. The system parameters can be indicated in the Pocket PC as simple text and also the analysis result can be displayed. 相似文献