全文获取类型
收费全文 | 9634篇 |
免费 | 1367篇 |
国内免费 | 766篇 |
专业分类
电工技术 | 849篇 |
综合类 | 767篇 |
化学工业 | 1348篇 |
金属工艺 | 272篇 |
机械仪表 | 297篇 |
建筑科学 | 401篇 |
矿业工程 | 472篇 |
能源动力 | 92篇 |
轻工业 | 442篇 |
水利工程 | 72篇 |
石油天然气 | 66篇 |
武器工业 | 58篇 |
无线电 | 1244篇 |
一般工业技术 | 1316篇 |
冶金工业 | 956篇 |
原子能技术 | 88篇 |
自动化技术 | 3027篇 |
出版年
2024年 | 75篇 |
2023年 | 186篇 |
2022年 | 325篇 |
2021年 | 374篇 |
2020年 | 426篇 |
2019年 | 405篇 |
2018年 | 442篇 |
2017年 | 482篇 |
2016年 | 455篇 |
2015年 | 400篇 |
2014年 | 623篇 |
2013年 | 716篇 |
2012年 | 706篇 |
2011年 | 658篇 |
2010年 | 429篇 |
2009年 | 454篇 |
2008年 | 457篇 |
2007年 | 526篇 |
2006年 | 476篇 |
2005年 | 436篇 |
2004年 | 383篇 |
2003年 | 362篇 |
2002年 | 354篇 |
2001年 | 297篇 |
2000年 | 218篇 |
1999年 | 159篇 |
1998年 | 138篇 |
1997年 | 130篇 |
1996年 | 93篇 |
1995年 | 106篇 |
1994年 | 74篇 |
1993年 | 62篇 |
1992年 | 63篇 |
1991年 | 50篇 |
1990年 | 62篇 |
1989年 | 41篇 |
1988年 | 10篇 |
1987年 | 16篇 |
1986年 | 12篇 |
1985年 | 19篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1982年 | 14篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
We discuss algorithms for learning and revising user profiles that can determine which World Wide Web sites on a given topic would be interesting to a user. We describe the use of a naive Bayesian classifier for this task, and demonstrate that it can incrementally learn profiles from user feedback on the interestingness of Web sites. Furthermore, the Bayesian classifier may easily be extended to revise user provided profiles. In an experimental evaluation we compare the Bayesian classifier to computationally more intensive alternatives, and show that it performs at least as well as these approaches throughout a range of different domains. In addition, we empirically analyze the effects of providing the classifier with background knowledge in form of user defined profiles and examine the use of lexical knowledge for feature selection. We find that both approaches can substantially increase the prediction accuracy. 相似文献
12.
This paper analyses the collaborative design ofa high-technology product, a neuromagnetometerused in the analysis of the activity of thehuman cortex. The producer, Neuromag Company istrying to transform the device from a basicresearch instrument into a means of clinicalpractice. This transition is analyzed as asimultaneous evolution of the product,producer-user network and user activities. Thenetwork is analyzed as a network of activitysystems. Each activity has a historicallyformed object and a motive of its own, as wellas a system of cultural means and expertise. Weuse these to explain and understand theinterests and points of view of the actors inrelation to the product and the contradictionsof the producer-user network. It is suggestedthat the emerging user needs of collectiveactors must be analyzed at three levels. At thefirst level, the use value of the product, itscapacity of solving the vital problems andchallenges of developing user activities, ischaracterized. The second-level analysisconcerns the creation and development of thenecessary complementary tools and services thatmake the implementation and use of the productpossible. This task presupposes collaborationbetween several communities of the innovationnetwork. The third level is the situatedpractical use of the product. In ourexperience, it is advantageous that researcherscontribute with their data to a dialogue inwhich the user needs are articulated. 相似文献
13.
The development of future mobile networks will be driven, in large part, by content and web based services. In this paper,
we examine several performance, scalability and architectural challenges faced by future mobile web applications and how advanced
mobile content delivery techniques can address these challenges. We review existing content delivery using a taxonomy that
consists of three categories: network scaling, end system acceleration, and content and protocol optimization. While wireline
content delivery focuses on network and server scalability, mobile content delivery will likely benefit most from optimizing
radio link usage. We also present our ongoing work in this area, which extends the functionality of edge caching to the terminal,
uses user interest correlation information to maintain low terminal power consumption and adds a new dimension to radio resource
management.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
14.
15.
Evan E. Anderson 《Information Systems》1988,13(4):327-333
Many organizations, best illustrated by libraries, have access to hundreds of databases possessing varying degrees of complimentary and overlapping records. While users may receive positive marginal benefits from data duplications, all databases and their services cannot be supported because of resource limitations. This paper attempts to conceptualize the problem of database collection in an environment of multiple databases, with differential content and performance characteristics, diverse users, and limited resources. It defines the database collection problem as a constrained zero-one integer programming problem and solves for the optimal combination or union of databases. Several extensions are shown, where special conditions are imposed on the relationships between databases and/or their availability. 相似文献
16.
分析了钼精矿Cu、Pb含量高的主要原因 ,通过实施一系列措施 ,达到了降低钼精矿中Cu、Pb含量的目的 相似文献
17.
Influence of pencil lead hardness on voltammetric response of graphite reinforcement carbon electrodes 总被引:1,自引:0,他引:1
Paulo Henrique Campos Prado Tavares Paulo Jorge Sanches Barbeira 《Journal of Applied Electrochemistry》2008,38(6):827-832
This work studied the voltammetric response of graphite reinforcement electrodes made of different pencil lead hardness. The
studies showed that harder graphite leads, regardless of their manufacturer, are more appropriate as electrode material for
voltammetric purposes due to their higher peak currents, increasing sensitivity and reproducibility, with ΔEp closer to the theoretical value for a reversible system. 相似文献
18.
Wood inspection with non-supervised clustering 总被引:9,自引:0,他引:9
Abstract. The appearance of sawn timber has huge natural variations that the human inspector easily compensates for mentally when determining
the types of defects and the grade of each board. However, for automatic wood inspection systems these variations are a major
source for complication. This makes it difficult to use textbook methodologies for visual inspection. These methodologies
generally aim at systems that are trained in a supervised manner with samples of defects and good material, but selecting
and labeling the samples is an error-prone process that limits the accuracy that can be achieved. We present a non-supervised
clustering-based approach for detecting and recognizing defects in lumber boards. A key idea is to employ a self-organizing
map (SOM) for discriminating between sound wood and defects. Human involvement needed for training is minimal. The approach
has been tested with color images of lumber boards, and the achieved false detection and error escape rates are low. The approach
also provides a self-intuitive visual user interface.
Received: 16 December 2000 / Accepted: 8 December 2001
Correspondence to: O. Silvén 相似文献
19.
本文研究了用金属有机物热发解法制备PLT8薄膜的工艺过程和基片对薄膜结构的影响,并且给出了铁电性能的测量结果。 相似文献
20.
In this paper, we propose an ID-based non-interactive zero-knowledge proof system based on the 1-out-of-2 noninteractive oblivious transfer protocol. This zero-knowledge proof system is secure against a newly discovered cheating attack. 相似文献