全文获取类型
收费全文 | 6004篇 |
免费 | 933篇 |
国内免费 | 168篇 |
专业分类
电工技术 | 196篇 |
技术理论 | 2篇 |
综合类 | 418篇 |
化学工业 | 2295篇 |
金属工艺 | 158篇 |
机械仪表 | 165篇 |
建筑科学 | 286篇 |
矿业工程 | 119篇 |
能源动力 | 164篇 |
轻工业 | 210篇 |
水利工程 | 47篇 |
石油天然气 | 52篇 |
武器工业 | 9篇 |
无线电 | 668篇 |
一般工业技术 | 698篇 |
冶金工业 | 229篇 |
原子能技术 | 32篇 |
自动化技术 | 1357篇 |
出版年
2024年 | 18篇 |
2023年 | 142篇 |
2022年 | 114篇 |
2021年 | 416篇 |
2020年 | 315篇 |
2019年 | 219篇 |
2018年 | 314篇 |
2017年 | 273篇 |
2016年 | 297篇 |
2015年 | 309篇 |
2014年 | 517篇 |
2013年 | 410篇 |
2012年 | 293篇 |
2011年 | 420篇 |
2010年 | 304篇 |
2009年 | 322篇 |
2008年 | 277篇 |
2007年 | 310篇 |
2006年 | 286篇 |
2005年 | 205篇 |
2004年 | 178篇 |
2003年 | 179篇 |
2002年 | 153篇 |
2001年 | 114篇 |
2000年 | 110篇 |
1999年 | 82篇 |
1998年 | 77篇 |
1997年 | 72篇 |
1996年 | 43篇 |
1995年 | 25篇 |
1994年 | 52篇 |
1993年 | 35篇 |
1992年 | 34篇 |
1991年 | 22篇 |
1990年 | 15篇 |
1989年 | 16篇 |
1988年 | 18篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 12篇 |
1984年 | 25篇 |
1983年 | 13篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 9篇 |
1978年 | 5篇 |
1977年 | 7篇 |
1976年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有7105条查询结果,搜索用时 15 毫秒
61.
DKNNS:面向延迟敏感型应用的可扩展精确分布式K近邻搜索算法研究 总被引:1,自引:0,他引:1
为了降低用户访问延迟,延迟敏感型网络应用需要选择合适的邻近服务节点响应用户访问请求.分布式K近邻搜索通过可扩展的选择距任意用户节点邻近的K个服务节点,可以有效满足网络应用延迟优化的目的.已有工作在精确度以及可扩展性等方面存在不足.针对可扩展精确的K近邻搜索问题,文中提出了分布式K近邻搜索方法DKNNS(distributed K nearest neighbor search).DKNNS将大量的服务节点组织为邻近性感知的多级环,通过最远节点搜索机制选择优化的K近邻搜索初始化节点,然后基于回退方式快速的在目标节点邻近区域发现K个近邻.基于理论分析,模拟测试以及真实环境下的部署实验发现,在不同规模的节点集合下,DKNNS算法能够确定近似最优的K个服务节点.且DKNNS的查询延迟,查询开销均显著低于Meridian算法.最后,DKNNS的返回结果相对于Meridian具有较高的稳定性. 相似文献
62.
从地震的发生频率上来看,我国是一个多发的国家。同时在地震中由于受到各种灾害而引起的损失也是最严重的。所以,对地震的信号进行实时性监测并完成信号数据的快速传输必须要应用先进的技术手段。文章主要介绍的就是目前应用十分广泛的3G技术在地震的网络系统中的安全应用。 相似文献
63.
64.
65.
Karuppaiah Geetha Veerasamy Anitha Mohamed Elhoseny Shankar Kathiresan Pourya Shamsolmoali Mahmoud M. Selim 《Expert Systems》2021,38(1)
Recently, medical image compression becomes essential to effectively handle large amounts of medical data for storage and communication purposes. Vector quantization (VQ) is a popular image compression technique, and the commonly used VQ model is Linde–Buzo–Gray (LBG) that constructs a local optimal codebook to compress images. The codebook construction was considered as an optimization problem, and a bioinspired algorithm was employed to solve it. This article proposed a VQ codebook construction approach called the L2‐LBG method utilizing the Lion optimization algorithm (LOA) and Lempel Ziv Markov chain Algorithm (LZMA). Once LOA constructed the codebook, LZMA was applied to compress the index table and further increase the compression performance of the LOA. A set of experimentation has been carried out using the benchmark medical images, and a comparative analysis was conducted with Cuckoo Search‐based LBG (CS‐LBG), Firefly‐based LBG (FF‐LBG) and JPEG2000. The compression efficiency of the presented model was validated in terms of compression ratio (CR), compression factor (CF), bit rate, and peak signal to noise ratio (PSNR). The proposed L2‐LBG method obtained a higher CR of 0.3425375 and PSNR value of 52.62459 compared to CS‐LBG, FA‐LBG, and JPEG2000 methods. The experimental values revealed that the L2‐LBG process yielded effective compression performance with a better‐quality reconstructed image. 相似文献
66.
67.
Stephen O. Dean 《Journal of Fusion Energy》1988,7(1):25-47
Fusion is an essentially inexhaustible source of energy that has the potential for economically attractive commercial applications with excellent safety and environmental characteristics. The primary focus for the fusion-energy development program is the generation of centralstation electricity. Fusion has the potential, however, for many other applications. The fact that a large fraction of the energy released in a DT fusion reaction is carried by high-energy neutrons suggests potentially unique applications. These include breeding of fissile fuels, production of hydrogen and other chemical products, transmutation or burning of various nuclear or chemical wastes, radiation processing of materials, production of radioisotopes, food preservation, medical diagnosis and medical treatment, and space power and space propulsion. In addition, fusion R&D will lead to new products and new markets.Each fusion application must meet certain standards of economic and safety and environmental attractiveness. For this reason, economics on the one hand, and safety and environment and licensing on the other hand, are the two primary criteria for setting long-range commercial fusion objectives. A major function of systems analysis is to evaluate the potential of fusion against these objectives and to help guide the fusion R&D program toward practical applications. The transfer of fusion technology and skills from the national laboratories and universities to industry is the key to achieving the long-range objective of commercial fusion applications. 相似文献
68.
赵彦香 《计算机光盘软件与应用》2012,(3):123+125
当今科技日新月异,经济发展迅猛,也带动了网络技术的不断高速发展,并广泛的应用于各大领域(军事、经济和政治等)。在计算机网络技术的广泛应用形势下,它的安全性问题也就逐渐的突显出来,引起了行业内人士的广泛关注。因此对网络应用中的安全性问题进行分析与探究是迫在眉睫的任务。本文首先论述了其应用中最常见的几大安全性问题,以及说明了对其安全问题所需要防护的相关策略。 相似文献
69.
林芳 《计算机光盘软件与应用》2012,(2):57-58
任何人在使用SQL Server数据库系统的时候,都希望自己能让SQL数据库发挥出他最佳的性能,但提供它性能的方法就是对其系统进行优化。本文主要通过笔者在日常工作生活中的经历和经验来简单讲述下SQL Server数据库在运用中的一些技巧。 相似文献
70.
Thermal sprayed aluminum and zinc provide long-term (> 20 years to first maintenance) corrosion control coatings. However,
this application is usually more expensive than painting or galvanizing if thermal spraying (metallizing) is not integrated
into the design and fabrication phases of new construction and repair projects. Aluminum and zinc metallized coatings are
tough enough to withstand fabrication, transportation, and assembly operations. The improved capabilities and productivity
of metallizing equipment for aluminum and zinc spraying are a major factor in their current cost competitiveness. The net
result is that the cost difference between metallizing, paint, and galvanizing is getting closer every day. Even though the
initial application cost of metallizing may be higher, the life cycle cost (LCC) and average equivalent annual costs (AEAC)
are lower than paint coating systems. Metallizing LCCs, when properly engineered into the construction schedule, are equal
to or less than paint coating LCCs. This article summarizes some metallizing considerations for installing improved corrosion
control coating systems in new construction and in maintenance and repair of infrastructure.
Editor’s Note: The following constants have been used to convert between English and Metric dimensions: 1ft2-0.0929 m2; 1lb/ft2-4.89 kg/m2; 1 mil=0.025mm.
Presented at the 5th National Thermal Spray Conference (NTSC-93), Infrastructure Maintenance and Repair Session, 10 June 1993,
Anaheim, CA. 相似文献