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   138篇
  免费   3篇
化学工业   22篇
机械仪表   1篇
建筑科学   6篇
能源动力   3篇
轻工业   25篇
水利工程   2篇
无线电   16篇
一般工业技术   17篇
冶金工业   35篇
原子能技术   1篇
自动化技术   13篇
  2023年   2篇
  2022年   4篇
  2021年   7篇
  2020年   3篇
  2019年   5篇
  2018年   3篇
  2017年   2篇
  2016年   5篇
  2015年   2篇
  2014年   4篇
  2013年   6篇
  2012年   3篇
  2011年   9篇
  2010年   3篇
  2009年   3篇
  2008年   1篇
  2006年   2篇
  2005年   3篇
  2004年   2篇
  2003年   1篇
  2002年   1篇
  2001年   3篇
  2000年   3篇
  1999年   3篇
  1998年   8篇
  1997年   8篇
  1996年   6篇
  1995年   3篇
  1994年   3篇
  1993年   4篇
  1992年   6篇
  1991年   1篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1985年   1篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
  1978年   3篇
  1977年   4篇
  1976年   5篇
  1975年   1篇
  1973年   1篇
  1972年   1篇
排序方式: 共有141条查询结果,搜索用时 15 毫秒
91.
Precise and accurate localization is important for safe autonomous driving. Given a traffic scenario which has multiple vehicles equipped with internal sensors for self-localization, and external sensors from the infrastructure for vehicle localization, vehicle-infrastructure communication can be used to improve the accuracy and precision of localization. However, as the number of vehicles in a scenario increases, associating measurement data with the correct source becomes increasingly challenging. We propose a solution utilizing the symmetric measurement equation filter (SME) for cooperative localization to address data association issue, as it does not require an enumeration of measurement-to-target associations. The principal idea is to define a symmetrical transformation which maps measurements to a homogeneous function, thereby effectively addressing several challenges in vehicle-infrastructure scenarios such as data association, bandwidth limitations and registration/configuration of the external sensor. To the best of our knowledge, the proposed solution is among the first to address all these issues of cooperative localization simultaneously, by utilizing the topology information of the vehicles.  相似文献   
92.

In the recent years the rapid growth of multimedia content makes the image retrieval a challenging research task. Content Based Image Retrieval (CBIR) is a technique which uses features of image to search user required image from large image dataset according to the user’s request in the form of query image. Effective feature representation and similarity measures are very crucial to the retrieval performance of CBIR. The key challenge has been attributed to the well known semantic gap issue. The machine learning has been actively investigated as possible solution to bridge the semantic gap. The recent success of deep learning inspires as a hope for bridging the semantic gap in CBIR. In this paper, we investigate deep learning approach used for CBIR tasks under varied settings from our empirical studies; we find some encouraging conclusions and insights for future research.

  相似文献   
93.
Zooplankton studies in Mexican rivers are few despite the fact that Mexico has >200 rivers. We present data on the seasonal diversity of rotifers during 2013–2014 from the river La Antigua, near Veracruz. We collected samples from 15 stations along a horizontal gradient of ~5 km, from the upper reaches to about 2 km from the sea. The physico‐chemical variables analysed were temperature, pH, dissolved oxygen, conductivity, nitrates, phosphates, Secchi depth and salinity. From each site, 80 L of water was filtered with a 50‐μm plankton net. Rotifers were identified and quantified using a Sedgewick Rafter cell. The river is shallow (maximum depth 2.5 m during the rainy season). Our observations indicated that the phytoplankton community was dominated by diatoms; the chlorophyll a concentrations ranged from 0.55 to 26.1 μg L?1 over the study period. We found >125 rotifer species belonging to 21 families, mostly from the Lecanidae, Brachionidae, Notommatidae and Lepadellidae. The density of rotifers was low, <40 ind. L?1, but species diversity (Shannon–Wiener) ranged, except for a onetime minimum of 0.25, from 2.0 to 4.0 for most part of the year. We also encountered Notholca cf. liepetterseni , an endemic species to Europe and Lecane yatseni , endemic to Asia. Other new records included Lecane rhytida and Ptygura melicerta . The importance of long‐term studies in rivers is emphasized. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   
94.
Feeding 1–2 g/day of cholesterol protected against ruminal hydrogenation caused a 20–30% drop in the secretion of milk fat by goats and cows. The effect was observed with goats fed conventional rations or with goats and cows fed rations supplemented with protected lipids, but was not observed with cows fed conventional rations, or when unprotected cholesterol and protected β-sitosterol was fed to these animals. The results suggest that this depression in milk fat is due to a decreased uptake of plasma triacylglycerol fatty acids by the mammary gland, induced by dietary cholesterol.  相似文献   
95.
A biosensor for glucose utilizing glucose oxidase (GOX) covalently coupled to poly(o‐amino benzoic acid) (PAB; a carboxy‐group‐functionalized polyaniline) is described. Amperometric response measurements conducted via unmediated and mediated (with ferrocene carboxylic acid and tetrathiafulvalene) reoxidation of GOX show that glucose can be detected over a wide range of concentrations. An enzyme‐conducting polymer‐mediator model provides for better charge transport in a biosensor. The optimal response, obtained at pH 5.5 and 300 K, lies in the 1–40 mM range. A kinetic plot yields the value of the apparent Michaelis–Menten constant, Kmapp. The operational stability of the PAB‐based glucose biosensor was experimentally determined to be about 6 days. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 662–667, 2000  相似文献   
96.
A mesoporous carbon developed from waste tire rubber, characterized by chemical analysis, FTIR, and SEM studies, was used as an adsorbent for the removal and recovery of a hazardous azo dye, Acid Blue 113. Surface area, porosity, and density were determined. The adsorption of the dye over the prepared adsorbent and a commercial activated carbon was achieved under different pH, adsorbate concentration, sieve size, adsorbent dosage, contact time and temperature conditions. Langmuir and Freundlich adsorption isotherm models were applied and thermodynamic parameters were calculated. Kinetic studies indicated that the adsorption process follow first order kinetics and particle diffusion mechanisms are operative. By percolating the dye solution through fixed-bed columns the bulk removal of the Acid Blue 113 was carried out and necessary parameters were determined to find out the percentage saturation of both the columns. Recovery of the dye was made by eluting 0.1 M NaOH through the column.  相似文献   
97.
A low-power CMOS reconfigurable analog-to-digital converter that can digitize signals over a wide range of bandwidth and resolution with adaptive power consumption is described. The converter achieves the wide operating range by (1) reconfiguring its architecture between pipeline and delta-sigma modes; (2) varying its circuit parameters, such as size of capacitors, length of pipeline, and oversampling ratio, among others; and (3) varying the bias currents of the opamps in proportion to the converter sampling frequency, accomplished through the use of a phase-locked loop (PLL). This converter also incorporates several power-reducing features such as thermal noise limited design, global converter chopping in the pipeline mode, opamp scaling, opamp sharing between consecutive stages in the pipeline mode, an opamp chopping technique in the delta-sigma mode, and other design techniques. The opamp chopping technique achieves faster closed-loop settling time and lower thermal noise than conventional design. At a converter power supply of 3.3 V, the converter achieves a bandwidth range of 0-10 MHz over a resolution range of 6-16 bits, and parameter reconfiguration time of twelve clock cycles. Its PLL lock range is measured at 20 kHz to 40 MHz. In the delta-sigma mode, it achieves a maximum signal-to-noise ratio of 94 dB and second and third harmonic distortions of 102 and 95 dB, respectively, at 10 MHz clock frequency, 9.4 kHz bandwidth, and 17.6 mW power. In the pipeline mode, it achieves a maximum DNL and INL of ±0.55 LSBs and ±0.82 LSBs, respectively, at 11 bits, at a clock frequency of 2.6 MHz and 1 MHz tone with 24.6 mW of power  相似文献   
98.
• How will Year 2000 technology problems create acquisitions opportunities? • If we are heading towards deflationary times, will the Year 2000 problem further exacerbate the cycle? • What are the technology action items today, so we can be prepared to buy our competitors if the regulators shut them down? • If, due to the Millennium Bug, our targets fail as going concerns, what does it take to plug them into our technology environment? © 1998 John Wiley & Sons, Ltd.  相似文献   
99.
The objective of present investigation was to formulate hydrogel containing glycyrrhizic acid loaded Ultra deformable vesicles i.e., transfersomes effective against atopic dermatitis. These were formulated using thin film hydration technique and this transferosomal suspension was loaded into a hydrogel base. This was characterized on the basis of parameters like particle size, shape and surface morphology, in vitro release, in vivo studies and skin deposition studies. The optimized formulation showed the in vitro release of 89.8% upto 24?h and following Higuchi’s equation (R2?=?0.971).The data obtained revealed that the formulation is able to be effective against atopic dermatitis.  相似文献   
100.
The importance of open and unbuilt neighborhood spaces in residential developments has been established by numerous scholars. Having a diverse nomenclature in varied contexts, these areas are indispensable yet often neglected and designated as leftovers in contemporary planning practice. With their usefulness in the Indian context of socially active and sometimes even intrusive communities, such spaces are rapidly losing their place in present-day residential environments due to the pressure of providing for the rapidly growing population coupled with mass migratory patterns. These neighborhood spaces that impart physical, psychological, and perceptual comfort to residents have been present in spontaneously developed traditional Indian cities due to their inherent order and integrity. Moreover, some contemporary housing environments by eminent designers have also utilized the virtues of well-designed neighborhood environments. This study is a comparative analysis of three selected projects, which aspire to devise suitable methods for contemporary Indian context and achieve neighborhood comfort and an overall sense of belongingness among residents.  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