全文获取类型
收费全文 | 363篇 |
免费 | 13篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 3篇 |
综合类 | 1篇 |
化学工业 | 91篇 |
金属工艺 | 14篇 |
机械仪表 | 15篇 |
建筑科学 | 9篇 |
能源动力 | 17篇 |
轻工业 | 34篇 |
水利工程 | 3篇 |
无线电 | 25篇 |
一般工业技术 | 71篇 |
冶金工业 | 40篇 |
原子能技术 | 1篇 |
自动化技术 | 53篇 |
出版年
2024年 | 3篇 |
2023年 | 8篇 |
2022年 | 13篇 |
2021年 | 18篇 |
2020年 | 17篇 |
2019年 | 12篇 |
2018年 | 19篇 |
2017年 | 22篇 |
2016年 | 18篇 |
2015年 | 2篇 |
2014年 | 20篇 |
2013年 | 34篇 |
2012年 | 18篇 |
2011年 | 19篇 |
2010年 | 16篇 |
2009年 | 13篇 |
2008年 | 16篇 |
2007年 | 10篇 |
2006年 | 12篇 |
2005年 | 6篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 8篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 9篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1980年 | 7篇 |
1979年 | 1篇 |
1976年 | 2篇 |
1973年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有377条查询结果,搜索用时 0 毫秒
81.
A multimodal biometric system is applied to recognize individuals as authentication, identification and verification for claimed identity. Multimodal biometrics increases the security level accuracy, spoof of attacks, noise in collected data, intra-class variations, inter-class variations, non universality etc. In this paper a multi modal biometric algorithm is designed by integrating iris, palm print, face and signature based on encoded discrete wavelet transform for image analysis and authentication. Multi level wavelet based fusion approach is applied, integrated and encoded into single composite image for matching decision. It reduces the memory size, increases the recognition accuracy and ERR using multimodal biometric approach when compared to individual biometric traits. The complexity of fusion and the reconstruction algorithm is suitable for many real time applications. 相似文献
82.
Dodderi Manjunatha Sagar Lee Erik Korshoj Katrina Bethany Hanson Partha Pratim Chowdhury Peter Britton Otoupal Anushree Chatterjee Prashant Nagpal 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(4)
Optical techniques for molecular diagnostics or DNA sequencing generally rely on small molecule fluorescent labels, which utilize light with a wavelength of several hundred nanometers for detection. Developing a label‐free optical DNA sequencing technique will require nanoscale focusing of light, a high‐throughput and multiplexed identification method, and a data compression technique to rapidly identify sequences and analyze genomic heterogeneity for big datasets. Such a method should identify characteristic molecular vibrations using optical spectroscopy, especially in the “fingerprinting region” from ≈400–1400 cm?1. Here, surface‐enhanced Raman spectroscopy is used to demonstrate label‐free identification of DNA nucleobases with multiplexed 3D plasmonic nanofocusing. While nanometer‐scale mode volumes prevent identification of single nucleobases within a DNA sequence, the block optical technique can identify A, T, G, and C content in DNA k‐mers. The content of each nucleotide in a DNA block can be a unique and high‐throughput method for identifying sequences, genes, and other biomarkers as an alternative to single‐letter sequencing. Additionally, coupling two complementary vibrational spectroscopy techniques (infrared and Raman) can improve block characterization. These results pave the way for developing a novel, high‐throughput block optical sequencing method with lossy genomic data compression using k‐mer identification from multiplexed optical data acquisition. 相似文献
83.
Sagar Chhetri Abeer Alsadoon Thair Al‐Dala'in P. W. C. Prasad Tarik A. Rashid Angelika Maag 《Computational Intelligence》2021,37(1):578-595
Accurate fall detection for the assistance of older people is crucial to reduce incidents of deaths or injuries due to falls. Meanwhile, vision‐based fall detection system has shown some significant results to detect falls. Still, numerous challenges need to be resolved. The impact of deep learning has changed the landscape of the vision‐based system, such as action recognition. The deep learning technique has not been successfully implemented in vision‐based fall detection system due to the requirement of a large amount of computation power and requirement of a large amount of sample training data. This research aims to propose a vision‐based fall detection system that improves the accuracy of fall detection in some complex environments such as the change of light condition in the room. Also, this research aims to increase the performance of the pre‐processing of video images. The proposed system consists of Enhanced Dynamic Optical Flow technique that encodes the temporal data of optical flow videos by the method of rank pooling, which thereby improves the processing time of fall detection and improves the classification accuracy in dynamic lighting condition. The experimental results showed that the classification accuracy of the fall detection improved by around 3% and the processing time by 40–50 ms. The proposed system concentrates on decreasing the processing time of fall detection and improving the classification accuracy. Meanwhile, it provides a mechanism for summarizing a video into a single image by using dynamic optical flow technique, which helps to increase the performance of image preprocessing steps. 相似文献
84.
The occurrence of enteric viruses in groundwater and soil was examined beneath three different sites where slow rate sewage irrigation of cropland is practiced. At all sites, the sewage was secondarily treated (aeration) before land application. Enteric viruses were isolated from wells beneath all sites. The lowest frequency of isolation was from wells beneath the one site practicing chlorination before application by spray irrigation. Viruses were detected in wells as deep as 27.5 m. 相似文献
85.
A cost‐effective, operationally simple and eco‐compatible protocol for the one‐pot synthesis of photochromic pyrans by the reaction of propargyl alcohols as well as propargyl ethers with differently substituted phenols under ambient atmosphere in aqueous medium has been developed using β‐cyclodextrin hydrate as an efficient, recyclable and stable catalyst. This is the first report where β‐cyclodextrin hydrate acted as a catalyst for an organic transformation but β‐cyclodextrin alone failed.
86.
U.B. Shinde Sagar E. Shirsath S.M. Patange S.P. Jadhav K.M. Jadhav V.L. Patil 《Ceramics International》2013,39(5):5227-5234
Stoichiometric compositions of ferrites with the chemical formula Li0.5?0.5xCoxFe2.4?0.5xDy0.1O4 with x=0, 0.25, 0.5, 0.75, 1.0 were prepared by the standard double sintering ceramic method. X-ray diffraction analysis confirmed the cubic spinel structure of the prepared samples. The structural, morphological and magnetic properties were studied by X-ray diffraction, infra-red spectroscopy (IR), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM) and ac susceptibility measurements. Lattice constant, grain size and density increase whereas porosity decreases with the increase in Co2+ substitution. IR measurements show the characteristic ferrite bands. Spectral absorption bands were observed in IR spectroscopic analysis at ν1=564?601 cm?1, ν2=486?519 cm?1 and ν3=551?578 cm?1. The cation distribution estimated by the X-ray diffraction is supported by magnetization and susceptibility studies. The saturation magnetization decreases from 44.25 to 17.14 emu/g whereas coercivity remarkably increases from 240.69 to 812.14 emu/g with increasing Co2+ substitution. The mechanisms involved are discussed. 相似文献
87.
Nadeem Iqbal Sadia Sagar Mohammad Bilal Khan Mohamed Ismail Bassyouni Zaffar M. Khan 《应用聚合物科学杂志》2013,130(6):4392-4400
Variant concentrations of ceramic fibers (CerFs) were incorporated into acrylonitrile butadiene rubber (NBR) to fabricate elastomeric ablative composites for ultrahigh temperature applications. The CerFs introduction into the polymer matrix has enhanced the ablation resistance up to 59% and successfully reduced the backface temperature of the polymer composite up to 110oC during the ultrahigh temperature ablation investigation. Thermal decomposition of the polymer composites was diminished up to 10% with increasing fiber concentration in the rubber matrix. Thermal conductivity was reduced equal to 63% while thermal impedance was enhanced up to 84% with the utmost fiber incorporation into the NBR matrix. The CerFs have adversely affected the mechanical properties of NBR matrix due to their brittle/inert nature and weak interface bonding with the host matrix. Scanning electron microscopy along with the energy dispersive x‐ray spectroscopy was used to examine the ablated specimens and the fiber dispersion within the host matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4392–4400, 2013 相似文献
88.
Sugrim Sagar Yi Zhang Linmin Wu Hye-Young Park Je-Hyun Lee Yeon-Gil Jung Jing Zhang 《Journal of Materials Engineering and Performance》2018,27(1):52-56
In this study, the room-temperature Charpy impact property of 3D-printed 15-5 stainless steel was investigated by a combined experimental and finite element modeling approach. The experimentally measured impact energy is 10.85 ± 1.20 J/cm2, which is comparable to the conventionally wrought and non-heat treated 15-5 stainless steel. In parallel to the impact test experiment, a finite element model using the Johnson–Cook material model with damage parameters was developed to simulate the impact test. The simulated impact energy is 10.46 J/cm2, which is in good agreement with the experimental data. The fracture surface from the experimentally tested specimen suggests that the 3D-printed specimens undergo predominately brittle fracture. 相似文献
89.
Onion (Allium cepa L.) is an important vegetable crop consumed primarily for its ability to enhance the flavor of other foods. The quality of onion depends on its pungency. While highly pungent onions are popular in India, less pungent ones are preferred in other countries. However, the variability in pungency in bulbs of different cultivars however has not been investigated. The present investigation was therefore undertaken to determine the pungency in three popular Indian onion cultivars viz. N-2-4-1, B-780 and Phule Safed. Randomly selected bulb samples of the cultivars were analyzed for the content of pyruvic acid, total soluble solids (TSS) and reducing, non-reducing and total sugars. The red variety N-2-4-1 showed higher level of pungency, while other two varieties were comparatively less pungent. 相似文献
90.
Ashim Gurung Khan Mamun Reza Sally Mabrouk Behzad Bahrami Rajesh Pathak Buddhi Sagar Lamsal Sheikh Ifatur Rahman Nabin Ghimire Raja Sekhar Bobba Ke Chen Jyotshna Pokharel Abiral Baniya Md Ashiqur Rahman Laskar Mao Liang Wenfeng Zhang Wen‐Hua Zhang Shangfeng Yang Kang Xu Qiquan Qiao 《Advanced functional materials》2020,30(30)
Photovoltaic power‐conversion systems can harvest energy from sunlight almost perpetually whenever sunrays are accessible. Meanwhile, as indispensable energy storage units used in advanced technologies such as portable electronics, electric vehicles, and renewable/smart grids, batteries are energy‐limited closed systems and require constant recharging. Fusing these two essential technologies into a single device would create a sustainable power source. Here, it is demonstrated that such an integrated device can be realized by fusing a rear‐illuminated single‐junction perovskite solar cell with Li4Ti5O12‐LiCoO2 Li‐ion batteries, whose photocharging is enabled by an electronic converter via voltage matching. This design facilitates a straightforward monolithic stacking of the battery on the solar cell using a common metal substrate, which provides a robust mechanical isolation between the two systems while simultaneously providing an efficient electrical interconnection. This system delivers a high overall photoelectric conversion‐storage efficiency of 7.3%, outperforming previous efforts on stackable integrated architectures with organic–inorganic photovoltaics. Furthermore, converter electronics facilitates system control with battery management and maximum power point tracking, which are inevitable for efficient, safe, and reliable operation of practical loads. This work presents a significant advancement toward integrated photorechargeable energy storage systems as next‐generation power sources. 相似文献