全文获取类型
收费全文 | 17937篇 |
免费 | 2870篇 |
国内免费 | 2150篇 |
专业分类
电工技术 | 2367篇 |
综合类 | 2073篇 |
化学工业 | 1500篇 |
金属工艺 | 494篇 |
机械仪表 | 820篇 |
建筑科学 | 721篇 |
矿业工程 | 336篇 |
能源动力 | 483篇 |
轻工业 | 904篇 |
水利工程 | 302篇 |
石油天然气 | 550篇 |
武器工业 | 214篇 |
无线电 | 2224篇 |
一般工业技术 | 1224篇 |
冶金工业 | 284篇 |
原子能技术 | 149篇 |
自动化技术 | 8312篇 |
出版年
2024年 | 50篇 |
2023年 | 258篇 |
2022年 | 475篇 |
2021年 | 543篇 |
2020年 | 632篇 |
2019年 | 567篇 |
2018年 | 529篇 |
2017年 | 644篇 |
2016年 | 775篇 |
2015年 | 815篇 |
2014年 | 1189篇 |
2013年 | 1233篇 |
2012年 | 1546篇 |
2011年 | 1492篇 |
2010年 | 1129篇 |
2009年 | 1283篇 |
2008年 | 1284篇 |
2007年 | 1410篇 |
2006年 | 1130篇 |
2005年 | 1054篇 |
2004年 | 825篇 |
2003年 | 638篇 |
2002年 | 559篇 |
2001年 | 489篇 |
2000年 | 386篇 |
1999年 | 332篇 |
1998年 | 218篇 |
1997年 | 215篇 |
1996年 | 204篇 |
1995年 | 175篇 |
1994年 | 145篇 |
1993年 | 132篇 |
1992年 | 115篇 |
1991年 | 67篇 |
1990年 | 69篇 |
1989年 | 52篇 |
1988年 | 31篇 |
1987年 | 26篇 |
1986年 | 22篇 |
1985年 | 27篇 |
1984年 | 27篇 |
1983年 | 22篇 |
1982年 | 24篇 |
1981年 | 16篇 |
1980年 | 21篇 |
1979年 | 16篇 |
1978年 | 9篇 |
1977年 | 16篇 |
1976年 | 7篇 |
1975年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
101.
The paper gives a method of model XLPE medium voltage cable insulation testing for partial discharges and electrical treeing
with a point to plane test geometry. Based on this method, a comparative estimate of insulation resistance to treeing and
partial discharges have been made. XLPE crosslinked by different methods (steam medium and hot nitrogen medium) and with varying
contents of inorganic filler kaolin were tested. The characteristics of partial discharges were measured by means of a pulse
height analyser characterized with a microscope. The data have been analysed statistically. 相似文献
102.
形态学边缘检测的新算法及其应用 总被引:3,自引:0,他引:3
刘岚岚 《红外与毫米波学报》1998,17(5):386-390
提出了一种基于数学形态学的边缘检测的所算法,该算法具有简便和灵活可编程控制等优点,比原来主算法更国完善,在实际应用中有着很好的前景,并给出了实验结果。 相似文献
103.
An algorithm for reconstructing a binary array of size N sx N from its forest of quadtree representation is presented. The algorithm traverses each tree of the forest in preorder and maps each ‘black’ node into the spatial domain. The time complexity in mapping is O(log N × Bn + Bp), where Bn is the number of black nodes in the forest and Bp is the number of black pixels in the N × N array. The algorithm has been implemented on an Apple II. 相似文献
104.
基于语法的元程序设计系统的自动生成技术 总被引:4,自引:0,他引:4
本文提出一种基于语法的元程序设计系统的自动生成技术,并开发了一个元程序设计系统的自动生成系统A-MPS。元程序设计系统是一种以程序作为操作对象的有效的程序设计工具,并具有广泛的应用。 相似文献
105.
From the principle of of the Domain Decomposition Method (DDM), we analyse the 2nd-order linear elliptic partial differential problems and link the Separated-Layers Algorithm (SLA) with DDM. The mathematical properties of SLA and numerical example are presented to obtain satisfactory computation results. For general linear differential ones, also are the structure of SLA and its characteristics discussed. 相似文献
106.
Buffer overflow vulnerabilities are one of the most commonly and widely exploited security vulnerabilities in programs. Most existing solutions for avoiding buffer overflows are either inadequate, inefficient or incompatible with existing code. In this paper, we present a novel approach for transparent and efficient runtime protection against buffer overflows. The approach is implemented by two tools: Type Information Extractor and Depositor (TIED) and LibsafePlus. TIED is first used on a binary executable or shared library file to extract type information from the debugging information inserted in the file by the compiler and reinsert it in the file as a data structure available at runtime. LibsafePlus is a shared library that is preloaded when the program is run. LibsafePlus intercepts unsafe C library calls such as strcpy and uses the type information made available by TIED at runtime to determine whether it would be ‘safe’ to carry out the operation. With our simple design we are able to protect most applications with a performance overhead of less than 10%. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
107.
用偏微分方程构造过渡面 总被引:9,自引:2,他引:7
用偏微分方程的构造曲面是一种新兴的方法,本文借若干算例说明如何用偏微分方程构造两已知曲面之间的过渡面。论文着重讨论用四阶方程构造一阶连续的过渡面。 相似文献
108.
本文应用故障树分析方法,对快中子零功率堆(DF-Ⅵ)在启动过程中发生临界事故的可能性做了初步的定量估计。结果表明,该堆每次启动发生临界事故的概率约为10~(-6)量级,得出确保装置启动安全的首要因素是选配合格的操作人员的结论,并对设备的改进提出了一些建议. 相似文献
109.
110.
Tree-based partitioning of date for association rule mining 总被引:1,自引:1,他引:0
The most computationally demanding aspect of Association Rule Mining is the identification and counting of support of the frequent sets of items that occur together sufficiently often to be the basis of potentially interesting rules. The task increases in difficulty with the scale of the data and also with its density. The greatest challenge is posed by data that is too large to be contained in primary memory, especially when high data density and/or low support thresholds give rise to very large numbers of candidates that must be counted. In this paper, we consider strategies for partitioning the data to deal effectively with such cases. We describe a partitioning approach which organises the data into tree structures that can be processed independently. We present experimental results that show the method scales well for increasing dimensions of data and performs significantly better than alternatives, especially when dealing with dense data and low support thresholds.
Shakil Ahmed received a first class BSc (Hons) degree from Dhaka University, Bangladesh, in 1990; and an MSc (first class), also Dhaka University, in 1992. He received his PhD from The University of Liverpool, UK, in 2005. From 2000 onwards he is a member of the Data Mining Group at the Department of Computer Science of the University of Liverpool, UK. His research interests include data mining, Association Rule Mining and pattern recognition.
Frans Coenen has been working in the field of Data Mining for many years and has written widely on the subject. He received his PhD from Liverpool Polytechnic in 1989, after which he took up a post as a RA within the Department of Computer Science at the University of Liverpool. In 1997, he took up a lecturing post within the same department. His current Data Mining research interests include Association rule Mining, Classification algorithms and text mining. He is on the programme committee for ICDM'05 and was the chair for the UK KDD symposium (UKKDD'05).
Paul Leng is professor of e-Learning at the University of Liverpool and director of the e-Learning Unit, which is responsible for overseeing the University's online degree programmes, leading to degrees of MSc in IT and MBA. Along with e-Learning, his main research interests are in Data Mining, especially in methods of discovering Association Rules. In collaboration with Frans Coenen, he has developed efficient new algorithms for finding frequent sets and is exploring applications in text mining and classification. 相似文献