全文获取类型
收费全文 | 50095篇 |
免费 | 2520篇 |
国内免费 | 155篇 |
专业分类
电工技术 | 708篇 |
综合类 | 65篇 |
化学工业 | 10596篇 |
金属工艺 | 2136篇 |
机械仪表 | 3242篇 |
建筑科学 | 1101篇 |
矿业工程 | 27篇 |
能源动力 | 2111篇 |
轻工业 | 3892篇 |
水利工程 | 271篇 |
石油天然气 | 91篇 |
武器工业 | 2篇 |
无线电 | 7834篇 |
一般工业技术 | 10664篇 |
冶金工业 | 4347篇 |
原子能技术 | 658篇 |
自动化技术 | 5025篇 |
出版年
2024年 | 50篇 |
2023年 | 570篇 |
2022年 | 871篇 |
2021年 | 1484篇 |
2020年 | 1070篇 |
2019年 | 1176篇 |
2018年 | 1430篇 |
2017年 | 1413篇 |
2016年 | 1750篇 |
2015年 | 1294篇 |
2014年 | 2088篇 |
2013年 | 3008篇 |
2012年 | 3265篇 |
2011年 | 3890篇 |
2010年 | 2815篇 |
2009年 | 2922篇 |
2008年 | 2811篇 |
2007年 | 2185篇 |
2006年 | 2033篇 |
2005年 | 1723篇 |
2004年 | 1572篇 |
2003年 | 1516篇 |
2002年 | 1329篇 |
2001年 | 1134篇 |
2000年 | 996篇 |
1999年 | 940篇 |
1998年 | 1693篇 |
1997年 | 1071篇 |
1996年 | 859篇 |
1995年 | 601篇 |
1994年 | 499篇 |
1993年 | 422篇 |
1992年 | 295篇 |
1991年 | 289篇 |
1990年 | 266篇 |
1989年 | 248篇 |
1988年 | 214篇 |
1987年 | 176篇 |
1986年 | 124篇 |
1985年 | 124篇 |
1984年 | 92篇 |
1983年 | 63篇 |
1982年 | 40篇 |
1981年 | 40篇 |
1980年 | 32篇 |
1979年 | 32篇 |
1978年 | 30篇 |
1977年 | 41篇 |
1976年 | 70篇 |
1973年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Jeon J.H. Kim H.S. Boo G.N. Song J.S. Lee E.W. Park H.W. 《Multimedia Tools and Applications》2000,11(2):197-214
A real-time MPEG-2 video codec system, called the KAIST image computing system (KICS), was developed using multiple multimedia video processors (MVP, TMS320C80). The number of computations and optimum implementation of the MPEG-2 algorithm were analyzed for real-time processing. An MVP simulator was used to perform the timing analysis for the real-time MPEG-2 encoding and decoding, and it verified the design of the KICS. Task partitioning and mapping of the MPEG-2 algorithm to multiple MVPs were performed based on load-balancing, minimum data I/O, and the properties of the MVP. The KICS uses five MVPs for MPEG-2 real-time encoding of a main profile at the main level whereas it uses three MVPs for real-time decoding. 相似文献
992.
We have designed an auditory guidance system for the blind using ultrasonic-to-audio signal transformation. We first investigated
the system requirements, and designed a simple but useful portable guidance system for the blind. The system derives visual
information using multiple ultrasonic sensors, and transforms it to binaural auditory information using a suitable technique.
The user can recognize the position of obstacles and the surrounding environment. The system is composed of two parts. One
is a glasses-type system, and the other is a cane-type system with guide wheels. The former functions as an environment sensor,
and the latter functions as a clear-path indicator. Wide-beam-angle ultrasonic sensors are used to detect bojects over a broader
range. The system is designed as a battery-supplied portable model. Our design is focused on low power consumption, small
size, light weight, and easy manipulation. 相似文献
993.
This paper introduces a novel neurofuzzy system based on polynomial fuzzy neural network (PFNN) architecture. A PFNN consists
of a set of if-then rules with appropriate membership functions (MFs) whose parameters are optimized via a hybrid genetic
algorithm. A polynomial neural network is employed in the defuzzification scheme to improve output performance and to select
appropriate rules. A performance criterion for model selection is defined to overcome the overfitting problem in the modeling
procedure. For a performance assessment of the PFNN inference system, two well-known problems are employed for a comparison
with other methods. The results of these comparisons show that the PFNN inference system out-performs the other methods and
exhibits robustness characteristics.
This work was presented in part at the Fourth International Symposium on Artificial Life and Robotics, Oita, Japan, January
19–22, 1999 相似文献
994.
995.
996.
Joon-Chul?Lee Moon-Sun?Kim Chul?Kyung?Kim Chan-Hwa?Chung Sung?M.?Cho Gui?Young?Han Ki?June?Yoon Byung-Woo?KimEmail author 《Korean Journal of Chemical Engineering》2003,20(5):862-868
Experiments were performed to investigate the effect of operating parameters on the photodegradation efficiency of paraquat
in a TiO2-suspended photoreactor with immersed UV lamps. TiO2 particles were prepared by a hydrothermal method. The removal rate of paraquat in the reactor was 0.54 mg/l/h with only air-sparging.
The removal rate in 24 h with both the UV radiation and air-sparging was 50% higher than that with only the UV radiation.
Variations of the paraquat concentration at the UV intensities of 4 and 8 W/m2 decreased slowly with time, but that at 12 W/m2 decreased more rapidly. The removal efficiency at the air-sparging flow rate of 1 //min increased as a UV light intensity
increased. pH value in the reactor at the UV intensity of 12 W/m2 decreased with time until 12 h and then increased with time over 12 h. 相似文献
997.
Kim CE Strintzis MG 《IEEE transactions on pattern analysis and machine intelligence》1980,(3):269-273
Fast computation algorithms are developed for twodimensional and general multidimensional convolutions. Two basic techniques (overlap-and-add, overlap-and-save) are described in detail. These techniques allow speed and storage requirement tradeoffs and they define a decomposition of the total convolution into partial convolutions that can be easily found by parallel use of fast sequential cyclic convolution algorithms. It is shown that unlike what is the case in one dimension, the ``overlap-and-save' method enjoys a clear advantage over the ``overlap-and-add' method with respect to speed and storage in multidimensional convolution. A specific computational burden is assessed for the case where these methods are used in conjunction with radix-2 fast Fourier transform algorithms. 相似文献
998.
Digital arcs in 3-D digital pictures are defined. The digital image of an arc is also defined. A digital arc is defined to be a digital line segment if it is the digital image of a line segment. It is shown that a digital line segment may be characterized by the chord property holding for its projections onto the coordinate planes. It is also shown that a digital line segment may not be characterized by its own chord property. A linear time algorithm is presented that determines whether or not a digital arc is a digital line segment. 相似文献
999.
Abstract This study applies a state-of-art optimization technique, SSDP/ESP (Sampling Stochastic Dynamic Programming with Ensemble Streamflow Prediction), to derive a monthly joint operating policy for the Nakdong multi-reservoir system in Korea. A rainfall-runoff model, SSARR (Streamflow Synthesis And Reservoir Regulation), is linked to the SSDP/ESP model to provide ESP scenarios for runoff during the next month in the Nakdong River basin. The primary advantage of the SSDP/ESP is that it updates the derived operating policy as new ESP forecasts become available. Another SSDP model that employs historical runoff scenarios (SSDP/Hist) is also developed. The main difference between the two SSDP models is that SSDP/Hist is an off-line model whereas the SSDP/ESP is on-line. The developed operating policies are tested with a simulation model using an object-oriented simulation software, STELLA. The simulation results show that SSDP/ESP is superior to SSDP/Hist with respect to the water supply criterion, although both models perform similarly with respect to the hydroelectric energy production criterion. 相似文献
1000.
Biofouling control by quorum sensing (QS) inhibition and the influence of membrane surface characteristics on biofilm formation and QS inhibition were investigated. Pseudomonas putida isolated from the bio-fouled reverse osmosis (RO) membranes in a real plant was used. Acylase was chosen as a model QS inhibitor. Bacteria on the membrane coupons were quantified with the heterotrophic plate count method. Cell distribution was imaged by a confocal laser scanning microscope. Results showed that biofilm formation on the membrane was reduced by acylase as it inhibits the activity of N-acylhomoserine lactone (AHL) which is a signal molecule of QS. It was also shown that membrane surface characteristics were influential factors affecting bacterial adhesion, biofilm formation, and QS inhibition. 相似文献