全文获取类型
收费全文 | 347483篇 |
免费 | 25429篇 |
国内免费 | 13239篇 |
专业分类
电工技术 | 18335篇 |
技术理论 | 41篇 |
综合类 | 20985篇 |
化学工业 | 59829篇 |
金属工艺 | 19835篇 |
机械仪表 | 22055篇 |
建筑科学 | 28138篇 |
矿业工程 | 11234篇 |
能源动力 | 9639篇 |
轻工业 | 20192篇 |
水利工程 | 5763篇 |
石油天然气 | 23813篇 |
武器工业 | 2689篇 |
无线电 | 38076篇 |
一般工业技术 | 41215篇 |
冶金工业 | 18281篇 |
原子能技术 | 3487篇 |
自动化技术 | 42544篇 |
出版年
2024年 | 1387篇 |
2023年 | 5396篇 |
2022年 | 9228篇 |
2021年 | 13297篇 |
2020年 | 9976篇 |
2019年 | 8513篇 |
2018年 | 9543篇 |
2017年 | 10856篇 |
2016年 | 9536篇 |
2015年 | 13253篇 |
2014年 | 16434篇 |
2013年 | 19552篇 |
2012年 | 21192篇 |
2011年 | 23142篇 |
2010年 | 20066篇 |
2009年 | 19045篇 |
2008年 | 18526篇 |
2007年 | 18166篇 |
2006年 | 19239篇 |
2005年 | 17016篇 |
2004年 | 11019篇 |
2003年 | 9645篇 |
2002年 | 9008篇 |
2001年 | 8060篇 |
2000年 | 8652篇 |
1999年 | 10280篇 |
1998年 | 8433篇 |
1997年 | 7143篇 |
1996年 | 6700篇 |
1995年 | 5462篇 |
1994年 | 4669篇 |
1993年 | 3267篇 |
1992年 | 2624篇 |
1991年 | 2000篇 |
1990年 | 1462篇 |
1989年 | 1169篇 |
1988年 | 974篇 |
1987年 | 655篇 |
1986年 | 480篇 |
1985年 | 331篇 |
1984年 | 219篇 |
1983年 | 151篇 |
1982年 | 167篇 |
1981年 | 105篇 |
1980年 | 77篇 |
1979年 | 28篇 |
1978年 | 3篇 |
1976年 | 1篇 |
1965年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Fan Zhang To-yat Cheung 《IEEE transactions on pattern analysis and machine intelligence》2003,29(1):1-14
The fault-state detection approach for blackbox testing consists of two phases. The first is to bring the system under test (SUT) from its initial state to a targeted state t and the second is to check various specified properties of the SUT at t. This paper investigates the first phase for testing systems specified as observable nondeterministic finite-state machines with probabilistic and weighted transitions. This phase involves two steps. The first step transfers the SUT to some state t' and the second step identifies whether t' is indeed the targeted state t or not. State transfer is achieved by moving the SUT along one of the paths of a transfer tree (TT) and state identification is realized by using diagnosis trees (DT). A theoretical foundation for the existence and characterization of TT and DT with minimum weighted height or minimum average weight is presented. Algorithms for their computation are proposed. 相似文献
42.
Yanqing Ji Hao Ying John Yen Shizhuo Zhu Daniel C. Barth‐Jones Richard E. Miller R. Michael Massanari 《国际智能系统杂志》2007,22(8):827-845
Discovering unknown adverse drug reactions (ADRs) in postmarketing surveillance as early as possible is highly desirable. Nevertheless, current postmarketing surveillance methods largely rely on spontaneous reports that suffer from serious underreporting, latency, and inconsistent reporting. Thus these methods are not ideal for rapidly identifying rare ADRs. The multiagent systems paradigm is an emerging and effective approach to tackling distributed problems, especially when data sources and knowledge are geographically located in different places and coordination and collaboration are necessary for decision making. In this article, we propose an active, multiagent framework for early detection of ADRs by utilizing electronic patient data distributed across many different sources and locations. In this framework, intelligent agents assist a team of experts based on the well‐known human decision‐making model called Recognition‐Primed Decision (RPD). We generalize the RPD model to a fuzzy RPD model and utilize fuzzy logic technology to not only represent, interpret, and compute imprecise and subjective cues that are commonly encountered in the ADR problem but also to retrieve prior experiences by evaluating the extent of matching between the current situation and a past experience. We describe our preliminary multiagent system design and illustrate its potential benefits for assisting expert teams in early detection of previously unknown ADRs. © 2007 Wiley Periodicals, Inc. Int J Int Syst 22: 827–845, 2007. 相似文献
43.
44.
Domain-Driven, Actionable Knowledge Discovery 总被引:1,自引:0,他引:1
Data mining increasingly faces complex challenges in the real-life world of business problems and needs. The gap between business expectations and R&D results in this area involves key aspects of the field, such as methodologies, targeted problems, pattern interestingness, and infrastructure support. Both researchers and practitioners are realizing the importance of domain knowledge to close this gap and develop actionable knowledge for real user needs. 相似文献
45.
Neural networks and blood cell identification 总被引:1,自引:0,他引:1
The objective of this project is to propose a method of identifying cells found in human blood and to classify them based upon their morphological features using neural networks. The project focuses on three major blood cell types, namely, erythrocytes, leukocytes and platelets. The data are collected using peripheral blood smears from clinical patients. The image acquisition requires 100x magnification on all the blood smears, the preprocessing involves the use of median and edge enhance filters; the feature extraction is done by performing the wavelet transform on the images. Finally classification of the blood cell types is done using ALOPEX and Back Propagation trained neural networks. The efficacy of both networks is then compared by comparing their outputs and number of iterations required to reach the final result. 相似文献
46.
Z. -G. Fan Y. -X. Zhuang G. Yang R. Shao G. -F. Zhang 《Journal of Alloys and Compounds》1993,200(1-2):33-36
The oxygen absorption process in highly aligned YBa2Cu3Ox samples in air and in pure oxygen was studied at several constant temperatures. The process can be expressed in two steps, a chemical reaction controlled step and a diffusion controlled step. The kinetic equations are as follows respectively:
(1 − at) ln(1 − at) + at = kDt
The activation energy was calculated using an Arrhenius equation. The technical conditions of heat treatment for oxygen absorption of highly aligned YBa2Cu3Ox crystals are discussed. 相似文献
47.
我国聚甲醛工业的供需分析 总被引:3,自引:0,他引:3
从国内聚甲醛树脂的生产、贸易及消费状况出发 ,分析了国内聚甲醛工业的供需现状并提出短期预测。 相似文献
48.
49.
Performance analysis of the bidirectional associative memory and animproved model from the matched-filtering viewpoint 总被引:1,自引:0,他引:1
Bai-Ling Zhang Bing-Zheng Xu Chung-Ping Kwong 《Neural Networks, IEEE Transactions on》1993,4(5):864-872
This paper discusses the bidirectional associative memory (BAM) model from the matched-filtering viewpoint and offers it a new interpretation. Our attention is focused on the problem of stability and attractivity of equilibrium states. Several sufficient and/or necessary conditions are presented. To improve the BAM performance, an exponential function is used to enhance the correlations between the binary vectors of the retrieval key and that of the stored pattern similar to the key. The modified model is shown to be asymptotically stable. Theoretical analysis and simulation results demonstrate that the modified model performs much better than the original BAM in terms of memory capacity and error correction capability. 相似文献
50.
提出了一种用双边带深侧槽的小尺寸圆形紧凑拉伸试样评定核压力容器(RPV)钢断裂韧性的单试作试验方法,给出了用该方法测定的两个厂家生产的核压力容器用A508CL3钢的断裂韧性参数,还与Charpy试样的试验结果及大尺寸标准试样的试验结果进行了比较。研究结果表明:用双边带深侧槽的小尺寸R-CT试样测得的断裂韧性值比相同恻槽深度预制疲劳裂纹Charpy试样的测试值更接近有效断裂韧性值,所以,用于核压力容器断裂韧性的监测是可行的。 相似文献