首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   120篇
  免费   3篇
电工技术   4篇
化学工业   19篇
金属工艺   1篇
机械仪表   2篇
建筑科学   12篇
能源动力   2篇
轻工业   4篇
石油天然气   4篇
无线电   9篇
一般工业技术   28篇
冶金工业   16篇
自动化技术   22篇
  2024年   1篇
  2023年   1篇
  2022年   4篇
  2021年   3篇
  2020年   1篇
  2019年   1篇
  2018年   6篇
  2017年   4篇
  2016年   1篇
  2015年   2篇
  2014年   1篇
  2013年   6篇
  2012年   5篇
  2011年   5篇
  2010年   1篇
  2009年   2篇
  2008年   5篇
  2006年   3篇
  2005年   2篇
  2004年   3篇
  2003年   4篇
  2002年   1篇
  2001年   3篇
  2000年   5篇
  1999年   2篇
  1998年   1篇
  1997年   3篇
  1996年   3篇
  1995年   6篇
  1994年   7篇
  1993年   2篇
  1992年   4篇
  1991年   7篇
  1990年   1篇
  1988年   2篇
  1985年   1篇
  1984年   2篇
  1982年   1篇
  1981年   2篇
  1980年   2篇
  1979年   2篇
  1978年   1篇
  1976年   4篇
排序方式: 共有123条查询结果,搜索用时 15 毫秒
21.
This research paper presents a framework for ranking of software engineering metrics based on expert opinion elicitation and fuzzy‐based matrix methodology. The proposed methodology is able to accommodate the imprecise and inexact data involved in the problem of ranking of software engineering metrics, vagueness and ambiguity occurring during expert (human) decision making and to depart from the complexity of formulation of the objective and the constraint function. The matrices lend themselves to mechanical manipulations and are useful for analyzing and deriving systems functions expeditiously to meet the objectives. The current research is based on software engineering metrics identified in an earlier study conducted by Lawrence Livermore National Laboratory. A set of ranking criteria were identified. Software engineering metrics are then ranked in ascending order using experts' opinion in accordance with the value of Permanent function on their criteria matrix. The proposed methodology has also been compared with other known methodologies. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   
22.
The problems of filtering and smoothing are considered for linear systems in an H setting, i.e. the plant and measurement noises have bounded energies (are in L2), but are otherwise arbitrary. Two distinct situations for the initial condition of the system are considered; the initial condition is assumed known in one case, while in the other the initial condition is not known but the initial condition, the plant, and measurement noise are in some weighted ball of RnXL2. Finite-horizon and infinite-horizon cases are considered. Necessary and sufficient conditions are presented for the existence of estimators (both filters and smoothers) that achieve a prescribed performance bound, and algorithms that result in performance within the bounds are developed. In case of smoothers, the optimal smoother is also presented. The approach uses basic quadratic optimization theory in a time-domain setting, as a consequence of which both linear time-varying and time-invariant systems can be considered with equal ease. (In the smoothing problem, for linear time-varying systems, one considers only the finite-horizon case)  相似文献   
23.
In the Bi-Sr-Ca-Cu-O system stringent conditions of heat-treatment lead to the formation of a mixture of both the low and highT c phases and obtaining a single-phase material becomes extremely difficult. This study reports preparation of samples with single superconducting transitions at ∼ 75 K and ∼ 108 K; the compositions of which correspond ton=2,3 in the series Bi2Sr2Ca n−1Cu n O4 + 2n . X-ray diffraction studies show that the lowerT c material is a relatively pure phase while the higherT c phase only co-exists with the lowerT c phase. The most obvious effect of doping the system with lead is to make the reaction take place faster and thereby increase the volume fraction of the 110K phase.  相似文献   
24.
Over the years, the attempts to elucidate the role of beneficial microorganisms in shaping human health are becoming fairly apparent. The functional impact conferred by such microbes is not only transmitted by viable cells or their metabolites but also through non-viable cells. Extensive research to unveil the protective action of such wonder bugs has resulted in categorizing the beneficial microflora and their bioactive metabolites into a variety of functional biotic concepts based on their intended applications in various forms. In the modern era, these are often termed as probiotics, prebiotics, synbiotics, postbiotics, next-generation probiotics, psychobiotics, oncobiotics, pharmabiotics, and metabiotics. Currently, the concept of traditional probiotics is being widened to include microbes beyond lactic acid bacteria. Indeed, this diversification has broadened the functional food portfolio from food to pharmaceuticals. In this context, the present review aims to summarize the existing biotic concepts and their differences thereof.  相似文献   
25.
The posterior pole vasculature of 100 patients with different sickling haemoglobinopathies was studied prospectively over a period of three years. Various abnormalities of the posterior pole vasculature were seen in 29 per cent of the patients. Continuous remodelling of the macular and perimacular vasculature occurred. Visual acuity was variably affected and sometimes remained intact.  相似文献   
26.
Acute choroidal ischemia as a complication of photocoagulation   总被引:2,自引:0,他引:2  
Acute choroidal vascular insufficiency as a complication of photocoagulation has been little noticed. In 17 eyes of 16 patients photocoagulated with either xenon or argon sources for proliferative sickle cell retinopathy, gray lesions of the fundus developed peripheral to the photocoagulation sites. Histologic examination of similar gray lesions produced in monkeys showed necrosis and atrophy of the outer half of the retina. Intense photocoagulation of the human fundus, even with smaller spot sizes, may occlude a choroidal artery, producing separate gray lesions of distinctive shape. The lesions in both the patients and the monkeys progressed to granular hyperpigmentation by two to three weeks after photocoagulation.  相似文献   
27.
    
A wireless body area networks (WBANs) is made up of tiny representations of the Internet of Medical Things (IoMT), which may be executed in the body or worn externally. Today, Internet of Things (IoT) has made it feasible to evaluate healthcare. The IoMT sends the patient's condition to the health center through the Internet rather than keeping them in the hospital all the time for therapy. IoT offers wireless connectivity between virtually anything and smart devices on one side. Data must be transferred to a doctor or other practitioner within the allotted time since this network works with medical and critical circumstances; this shows that routing is the most important problem. Routing is therefore viewed as a very significant difficulty in WBANs. The simulation findings show that, for the WBAN under consideration, the IoT-based stable increased-throughput multi-hop protocol for link efficiency protocol has better throughput, end-to-end delay, and propagation delay compared to adaptive threshold-based thermal-aware energy-efficient multi-hop protocol. Higher packet delivery to the sink is a result of longer stability periods, which is very desirable for ongoing patient monitoring during the COVID-19 pandemic. This research also identifies potential paths for the development of WBANs of the next generation and suggests ways to boost the selected communication systems' productivity in WBAN solutions for health monitoring.  相似文献   
28.
Purpose: Ultrasound (US) guidance in facet joint injections has been reported previously as an alternative to imaging modalities with ionizing radiation. However, this technique has not been adopted in the clinical routine, due to difficulties in the visualization of the target joint in US and simultaneous manipulation of the needle. Methods: We propose a technique to increase targeting accuracy and efficiency in facet joint injections. This is achieved by electromagnetically tracking the positions of the US transducer and the needle, and recording tracked US snapshots (TUSS). The needle is navigated using the acquired US snapshots. Results: In cadaveric lamb model, the success rate of facet joint injections by five orthopedic surgery residents significantly increased from 44.4% with freehand US guidance to 93.3% with TUSS guidance. Needle insertion time significantly decreased from 47.9 ± 34.2?s to 36.1 ± 28.7?s (mean ± SD). In a synthetic human spine model, a success rate of 96.7% was achieved with TUSS. The targeting accuracy of the presented system in a gel phantom was 1.03 ± 0.48?mm (mean ± SD). Conclusion: Needle guidance with TUSS improves the success rate and time efficiency in spinal facet joint injections. This technique readily translates also to other spinal needle placement applications.  相似文献   
29.
Journal of Materials Science: Materials in Electronics - The reported work presents an ultrafast and ultrasensitive sensing platform for the precise and reliable trace-level detection of Methyl...  相似文献   
30.
OBJECTIVES: To compare microleakage of three self‐etch adhesives and to analyze enamel surface morphology and interfacial morphology of resin–enamel and resin–dentin interface under scanning electron microscope (SEM). EXPERIMENTAL DESIGN: Study was conducted in 65 extracted human premolars. Class V cavities were prepared in 45 teeth and assigned to three groups (n = 15) according to three self‐etch adhesives (OptiBond All‐in‐One, iBond, and Adper Prompt L‐Pop). After restoration, 10 samples from each group were used to assess microleakage at enamel and dentin margin. Five samples from each group were used for analysis of interfacial morphology at resin–enamel and resin–dentin interface under SEM. Remaining 20 teeth were used to prepare flat enamel buccal surfaces to analyze the difference in surface morphology after treatment with three adhesives (n = 5 each) and 36% phosphoric acid treatment (n = 5). PRINCIPAL OBSERVATIONS: At enamel margin, Prompt L‐Pop depicted least leakage of all the three adhesives and also showed best interfacial adaptation under SEM. At dentin margin, OptiBond All‐in‐One showed significant less leakage than iBond and Prompt L‐Pop. On flat enamel surface, phosphoric acid produced the most retentive etching pattern when compared with the three adhesives. CONCLUSION: Prompt L‐Pop showed the best bonding effectiveness in enamel, whereas OptiBond All‐in‐One performed significantly better in dentin. Microsc. Res. Tech. 2012. © 2012 Wiley Periodicals, Inc.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号