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1.
Graft copolymerization of 4‐vinylpyridine (4‐VP) onto guar gum (GOH) using potassium monopersulfate (PMS)/thioacetamide (TAA) as a redox pair was studied in an aqueous medium under inert atmosphere. The concentration of potassium monopersulfate and thioacetamide should be 1.0 × 10?2 and 5.0 × 10?3 mol dm?3, respectively, for highest grafting ratio and efficiency. Efficient grafting was observed at 19.25 × 10?2 and 4.87 × 10?2 mol dm?3 concentration of 4‐vinylpyridine and sulfuric acid, respectively. The optimum temperature for grafting is 30°C. As the time period of reaction is increased, the grafting ratio increases, whereas efficiency decreases. The plausible mechanism of grafting has been suggested. A sample of guar gum and guar‐ g‐4‐vinylpyridine were subjected to thermogravimetric analysis with the objective of studying the effect of grafting 4‐vinylpyridine on the thermal stability of guar gum. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2380–2385, 2002 相似文献
2.
Kavita Krishnaswamy Ravi Kuber Tim Oates 《Universal Access in the Information Society》2016,15(4):609-627
Limb repositioning is necessary for individuals with severe physical disabilities to sustain muscle strength and prevent pressure sores. As robotic technologies become ubiquitous, these tools offer promise to support the repositioning process. However, research has yet to focus on ways in which individuals with severe physical disabilities can control robots for these tasks. This paper presents a study that examines the needs and attitudes of potential users with physical disabilities to control a robotic aid for limb repositioning. Subjects expressed interest in using brain–computer interface (BCI) and speech recognition technologies for purposes of executing robotic tasks. The performance of four subjects controlling arm movements on an avatar through the keyboard, mouse, BCI, and Dragon NaturallySpeaking speech recognition was evaluated. Although BCI and speech technologies may limit physical fatigue, more challenges were faced using BCI and speech conditions compared to the keyboard and mouse. This research promotes accessibility into mainstream robotic technologies and represents the first step in the development of a robotic prototype using a BCI and speech recognition technologies for limb repositioning. 相似文献
3.
Miloš Hašan Edgar Velázquez‐Armendáriz Fabio Pellacini Kavita Bala 《Computer Graphics Forum》2008,27(4):1105-1114
Rendering animations of scenes with deformable objects, camera motion, and complex illumination, including indirect lighting and arbitrary shading, is a long‐standing challenge. Prior work has shown that complex lighting can be accurately approximated by a large collection of point lights. In this formulation, rendering of animation sequences becomes the problem of efficiently shading many surface samples from many lights across several frames. This paper presents a tensor formulation of the animated many‐light problem, where each element of the tensor expresses the contribution of one light to one pixel in one frame. We sparsely sample rows and columns of the tensor, and introduce a clustering algorithm to select a small number of representative lights to efficiently approximate the animation. Our algorithm achieves efficiency by reusing representatives across frames, while minimizing temporal flicker. We demonstrate our algorithm in a variety of scenes that include deformable objects, complex illumination and arbitrary shading and show that a surprisingly small number of representative lights is sufficient for high quality rendering. We believe out algorithm will find practical use in applications that require fast previews of complex animation. 相似文献
4.
Ghang Lee Charles M. Eastman Tarang Taunk Chun-Heng Ho 《International journal of human-computer studies》2010,68(1-2):90-104
This study proposes usability principles for the user interfaces (UI) design of complex 3D parametric architectural design and engineering tools. Numerous usability principles have been developed for generic desktop or web applications. The authors tried to apply existing usability principles as guidelines for evaluating complex 3D design and engineering applications. However, the principles were too generic and high-level to be useful as design or evaluation guidelines. The authors, all with more than 10 or 30 years of experience with various CAD systems, selected and reviewed 10 state-of-the-art 3D parametric design and engineering applications and captured what they thought were best practices, as screenshots and videos. The collected best practices were reviewed through a series of discussion sessions. During the discussion sessions, UI design principles underlying the collected best practices were characterized in the line of existing UI principles. Based on the best practices and the derived common UI principles, a new set of refined and detailed UI principles were proposed for improving and evaluating 3D parametric engineering design tools in the future. 相似文献
5.
Cross Virtual Concatenation is the new technique proposed for bandwidth efficient transmission of data over SDH networks.
SDH networks came into existence for reliable voice transmission. As the demand of data traffic grew in wide area networks,
new technologies were developed and standardized for data transmission over SDH networks. The technologies used namely, GFP
(generic framing procedure), VCAT (virtual concatenation) and LCAS (link capacity adjustment scheme) enable network operator
to provide integrated voice and data services over their legacy SDH infrastructure. Data packets are encapsulated using framing
protocols GFP. VCAT is a process of distributing the GFP framed data payload in number of virtual channels of same capacity
forming a Virtually Concatenated Group (VCG). LCAS is used for dynamic bandwidth allocation. LCAS enhances the VCAT scheme
with hitless in service addition and removal of VC’s to/from the VCG.VCAT combines homogeneous virtual channels together which
in some cases limits the performance of VCAT. This paper describes the implementation of new concatenation technology named
cross virtual concatenation (CVC), which combines heterogeneous VC’s together to utilize the SDH bandwidth more efficiently.
CVC implementation requires only end node equipments to be upgraded as VCG members travel through the link similar to the
conventional VCAT. This paper proposes FPGA implementation of transmitter and receiver circuits for 100 Mbps Ethernet data
transmission over next Generation SDH systems using CVC, where two types of VC’s namely VC-3 and VC-12 are used for data transmission.
Total Transmission delay is calculated as 125 μs. There is no complexity added at the receiver side due to this delay. The
receiver is designed for 32 ms differential delay compensation which can be increased up to maximum 256 ms by increasing the
buffer size at the receiver. 相似文献
6.
This paper focuses on developing an area efficient hyperbolic Coordinate Rotation Digital Computer (CORDIC) algorithm with performance improvement. The algorithm eliminates the need of scale factor calculation in the Range of Convergence (ROC). At the same time the range of convergence offered is higher than the conventional CORDIC ROC in the hyperbolic rotation mode. Being the only kind of algorithm in hyperbolic rotation with sign sequence μ?=?1 always, one complete operation requires just 5 iterations. Thus the pipelined implementation has 5 stages which provides a 50% increase in throughput in comparison to conventional CORDIC. As far as the area improvement is considered, 16-bit processor can be realized using 56% less number of full adders required by Flat-CORDIC. The x and y datapath are based on series expansion of hyperbolic functions. The complete algorithm design along with pipelined architecture implementation is detailed. 相似文献
7.
Carbon dioxide emission and its regulation at land–water interface downstream of a point source at Ganga River (India) 下载免费PDF全文
Deepa Jaiswal Ekabal Siddiqui Kavita Verma Jitendra Pandey 《Water and Environment Journal》2018,32(3):351-357
The streams and rivers are considered hotspots of CO2 exchange; and representative direct CO2 emission measurements are essential for a correct regional estimate. We measured CO2 emission flux at 15 sites at land–water interface downstream of a point source during low flow for three consecutive months for the year 2017. The general range of CO2 efflux observed here was close to the results of regional studies, although values near the point source were disproportionately high (>350 mg/m2/h). CO2 emission flux showed strong dependence on total organic carbon (TOC; R2 = 0.96; P < 0.001), (R2 = 0.88; P < 0.001), soluble reactive‐P (SRP; R2 = 0.91; P < 0.001) and microbial activity measured in terms of fluorescein diacetate activity (FDAase; R2 = 0.92; P < 0.001) and substrate induced respiration (SIR; R2 = 0.96; P < 0.001). Because point source‐associated interfaces provide heterogeneous habitats, our study suggests the need for large scale monitoring of CO2 emission at land–water interface of major rivers for more correctly presenting the regional scale CO2 budget. 相似文献
8.
Romero-Canyas Rainer; Downey Geraldine; Reddy Kavita S.; Rodriguez Sylvia; Cavanaugh Timothy J.; Pelayo Rosemary 《Canadian Metallurgical Quarterly》2010,99(5):802
Societies and social scientists have long held the belief that exclusion induces ingratiation and conformity, an idea in contradiction to robust empirical evidence linking rejection with hostility and aggression. The classic literatures on ingratiation and conformity help resolve this contradiction by identifying circumstances under which rejection may trigger efforts to ingratiate. Jointly, findings from these literatures suggest that when people are given an opportunity to impress their rejecters, ingratiation is likely after rejection experiences that are harsh and that occur in important situations that threaten the individual's self-definition. Four studies tested the hypothesis that people high in rejection sensitivity and therefore dispositionally concerned about rejection will utilize opportunities to ingratiate after harsh rejection in situations that are self-defining. In 3 studies of situations that are particularly self-defining for men, rejection predicted ingratiation among men (but not women) who were high in rejection sensitivity. In a 4th study, harsh rejection in a situation particularly self-defining for women predicted ingratiation among highly rejection-sensitive women (but not men). These findings help identify the specific circumstances under which people are willing to act in socially desirable ways toward those who have rejected them harshly. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
Kavita Mathur Abdel-Fattah M Seyam David Hinks R Alan Donaldson 《Coloration Technology》2008,124(1):48-55
A geometric model combined with a colour model to predict the colour contribution of each pre-coloured yarn in terms of colour attributes of each area of a Jacquard pattern was developed. To validate the predicted calculations (colorimetric data), a visual assessment experiment was conducted to evaluate the difference between predicted and the actual colour appearance of the woven pattern. The results from the psychophysical evaluation of the woven samples and their predicted colour values showed high correlation between the predicted and experimental data. Therefore, the model has potential to eliminate subjective evaluations and reduce prototype sample production by automating the process of weave/colour simulation. 相似文献
10.
Kavita Mathur David Hinks Abdel‐Fattah M. Seyam Robert Alan Donaldson 《Color research and application》2009,34(3):225-232
Jacquard woven fabrics are made from colored yarns and different weaves for designing complex pictorial and other patterning effects. The final visualized color effect is the result of assigning weave designs to different areas of the pattern to be created. The current practice in creating Jacquard woven fabric designs is to produce many samples in a trial‐and‐error attempt to match artwork colors. An ability to simulate accurately the appearance of a design prior to manufacture is highly desirable to reduce trial‐and‐error sample production. No automated accurate digital color methodology is yet available to assist designers in matching the patterned woven fabric to the desired artwork. To achieve this, we developed a geometrical model to predict the color contribution of each yarn on the face of the fabric. The geometrical model combined with a Kubelka‐Munk based color mixing model allowed the prediction of the reflectance properties of the final color for a given design. We compared the predicted and experimental values of the reflectance properties for a range of fabrics using the same geometric model with three separate color mixing models. The geometrical model combined with a log‐based color mixing model produced reasonable agreement between predicted and measured ΔEab, with an average ΔEab of approximately five. © 2009 Wiley Periodicals, Inc. Col Res Appl, 34, 225–232, 2009 相似文献