全文获取类型
收费全文 | 75814篇 |
免费 | 711篇 |
国内免费 | 689篇 |
专业分类
电工技术 | 1429篇 |
综合类 | 47篇 |
化学工业 | 11172篇 |
金属工艺 | 3444篇 |
机械仪表 | 2637篇 |
建筑科学 | 1646篇 |
矿业工程 | 503篇 |
能源动力 | 1857篇 |
轻工业 | 6381篇 |
水利工程 | 846篇 |
石油天然气 | 2303篇 |
武器工业 | 41篇 |
无线电 | 7195篇 |
一般工业技术 | 16438篇 |
冶金工业 | 13440篇 |
原子能技术 | 2628篇 |
自动化技术 | 5207篇 |
出版年
2022年 | 575篇 |
2021年 | 904篇 |
2020年 | 696篇 |
2019年 | 781篇 |
2018年 | 1549篇 |
2017年 | 1563篇 |
2016年 | 1760篇 |
2015年 | 944篇 |
2014年 | 1556篇 |
2013年 | 3565篇 |
2012年 | 2356篇 |
2011年 | 2818篇 |
2010年 | 2368篇 |
2009年 | 2639篇 |
2008年 | 2617篇 |
2007年 | 2552篇 |
2006年 | 2182篇 |
2005年 | 1914篇 |
2004年 | 1837篇 |
2003年 | 1788篇 |
2002年 | 1703篇 |
2001年 | 1676篇 |
2000年 | 1670篇 |
1999年 | 1581篇 |
1998年 | 3972篇 |
1997年 | 2799篇 |
1996年 | 2053篇 |
1995年 | 1593篇 |
1994年 | 1385篇 |
1993年 | 1403篇 |
1992年 | 1002篇 |
1991年 | 1065篇 |
1990年 | 1079篇 |
1989年 | 1059篇 |
1988年 | 959篇 |
1987年 | 888篇 |
1986年 | 887篇 |
1985年 | 943篇 |
1984年 | 778篇 |
1983年 | 769篇 |
1982年 | 681篇 |
1981年 | 697篇 |
1980年 | 668篇 |
1979年 | 646篇 |
1978年 | 629篇 |
1977年 | 801篇 |
1976年 | 987篇 |
1975年 | 581篇 |
1974年 | 551篇 |
1973年 | 543篇 |
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
911.
The effects of an educational electronic book (e-book) on 149 five- to six-year-old kindergarteners’ emergent literacy levels were researched in two SES groups: low (LSES) (79 children) vs. middle (MSES) (70 children). In each SES group, children were randomly assigned to four groups. Three groups were assigned to work individually in one of three e-book activity modes: “Read story only”, “Read with dictionary”, or “Read and play” during three similar activity sessions and the fourth group served as a control which received the regular program of the kindergarten. Pre- and post-intervention emergent literacy measures included word meaning, word recognition, and phonological awareness. Results show that word meaning of children from both middle and low SES improved following the educational e-book activity, regardless of mode. Second, LSES children’s emergent literacy levels showed relatively greater improvement rates than did those of the MSES children. Third, children in the “Read with dictionary” and “Read and play” activity modes showed more improvement in their emergent literacy levels than did those in the “Read story only” mode. Implications for future research and for education are discussed. 相似文献
912.
Brain reading using full brain support vector machines for object recognition: there is no "face" identification area 总被引:1,自引:0,他引:1
Over the past decade, object recognition work has confounded voxel response detection with potential voxel class identification. Consequently, the claim that there are areas of the brain that are necessary and sufficient for object identification cannot be resolved with existing associative methods (e.g., the general linear model) that are dominant in brain imaging methods. In order to explore this controversy we trained full brain (40,000 voxels) single TR (repetition time) classifiers on data from 10 subjects in two different recognition tasks on the most controversial classes of stimuli (house and face) and show 97.4% median out-of-sample (unseen TRs) generalization. This performance allowed us to reliably and uniquely assay the classifier's voxel diagnosticity in all individual subjects' brains. In this two-class case, there may be specific areas diagnostic for house stimuli (e.g., LO) or for face stimuli (e.g., STS); however, in contrast to the detection results common in this literature, neither the fusiform face area nor parahippocampal place area is shown to be uniquely diagnostic for faces or places, respectively. 相似文献
913.
Product development is an important but also dynamic, lengthy and risky phase in the life of a new product. The optimisation of the product development phase through extensive knowledge of the involved procedures is believed to reduce the risks and improve the final product quality. Artificial intelligence and expert systems have been used successfully in optimising the development phase of some new products as it will be demonstrated by the first sections of this publication. This paper presents the first module of an expert system, a neural network architecture that could predict the reliability performance of a vehicle at later stages of its life by using only information from a first inspection after the vehicle’s prototype production. The paper demonstrates how a tool like neural networks can be designed and optimised for use in reliability performance predictions. Also, this paper presents an optimisation methodology that enabled the neural network to deal with the limited amount of available training data, common during new product development, and to finally achieve acceptable prediction performance with small error. A case example is presented to demonstrate the methodology. 相似文献
914.
This paper gives a detailed analysis of the error surfaces of certain recurrent networks and explains some difficulties encountered in training recurrent networks. We show that these error surfaces contain many spurious valleys, and we analyze the mechanisms that cause the valleys to appear. We demonstrate that the principle mechanism can be understood through the analysis of the roots of random polynomials. This paper also provides suggestions for improvements in batch training procedures that can help avoid the difficulties caused by spurious valleys, thereby improving training speed and reliability. 相似文献
915.
In this paper, we address the problem of agent loss in vehicle formations and sensor networks via two separate approaches: (1) perform a ‘self‐repair’ operation in the event of agent loss to recover desirable information architecture properties or (2) introduce robustness into the information architecture a priori such that agent loss does not destroy desirable properties. We model the information architecture as a graph G(V, E), where V is a set of vertices representing the agents and E is a set of edges representing information flow amongst the agents. We focus on two properties of the graph called rigidity and global rigidity, which are required for formation shape maintenance and sensor network self‐localization, respectively. For the self‐repair approach, we show that while previous results permit local repair involving only neighbours of the lost agent, the repair cannot always be implemented using only local information. We present new results that can be applied to make the local repair using only local information. We describe implementation and illustrate with algorithms and examples. For the robustness approach, we investigate the structure of graphs with the property that rigidity or global rigidity is preserved after removing any single vertex (we call the property as 2‐vertex‐rigidity or 2‐vertex‐global‐rigidity, respectively). Information architectures with such properties would allow formation shape maintenance or self‐localization to be performed even in the event of agent failure. We review a characterization of a class of 2‐vertex‐rigidity and develop a separate class, making significant strides towards a complete characterization. We also present a characterization of a class of 2‐vertex‐global‐rigidity. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
916.
Yu. E. Berezkin S. A. Borinskaya A. V. Kuznetsova O. V. Sen’ko 《Pattern Recognition and Image Analysis》2009,19(4):630-633
This work is devoted to the development and substantiation of intellectual data mining as applied to studying folklore and
mythological traditions. The approach is based on use of the functions of distance between traditions. The examples of application
of the methods developed to investigate the interrelation between folklore traditions of the American continent are considered. 相似文献
917.
A. O. Korepanov N. Yu. Ilyasova A. V. Kupriyanov 《Optical Memory & Neural Networks》2009,18(4):343-348
A problem of analyzing blood vessels on retinal images is considered. We suggest a method for extracting vessels using a wavelet
transform. The wavelet transform is modified by adding a wavelet rotation parameter and normalization with respect to the
signal energy within the wavelet carrier limits. The new methods, for constructing the vessel central lines based on the modified
wavelet transform, are being used for vessels geometrical parameters estimation. The parameters of vessels that are located
at the edge of the optic nerve disk are then used while diagnostic criteria formation for eye-ground pathological changes
determining. 相似文献
918.
The reasons of the absence of interoperability of the National system of electronic digital signatures (EDS) are analyzed
based on systems analysis. An attempt is made to substantiate the minimax (minimum costs and maximum results) way of solving
interoperability problems in EDS infrastructure in both Ukraine and foreign states. 相似文献
919.
E. V. Ershov V. V. Selivanovskikh O. G. Ganicheva 《Pattern Recognition and Image Analysis》2009,19(1):103-105
The analysis of methods of images handling is carried out, the method of dynamic threshold division which is based on the
calculation of weight coefficient of points in the local area is suggested. The method of adaptive adjustment of the size
of the local area of the image representation is carried out to define the threshold value. Also methods of binary recursive
filtration and mathematical morphology to reduce interference are introduced.
The article is published in the original.
Evgenii Valentinovich Ershov. The first pro-rector, head of the department of PC software, professor of the Cherepovetsk State University. Finished postgraduate
studies at the North-Western Polytechnic Correspondence Institute (the city of St. Petersburg) in 1993 and defended a Ph.D.
thesis on specialty 05.02.11 “Methods of Control and Diagnostics in Mechanical Engineering.” Circle of scientific interests:
the development of methods and principles for the building of multi-functional technical vision systems, their mathematical
and software support. Five postgraduate students defended theses under his supervision. Author of 170 scientific and teaching
works, including 4 monographs, 85 articles, of which 12 were published in reviewed journals, 39 theses of reports, 2 reports
on SRD, 3 patents. Took part in 20 scientific and technical conferences in Moscow, St. Petersburg, Cherepovetsk, Kursk, Tambov,
Vologda, Tula, Krasnoyarsk, Yoshkar Ola, and Kemerovo.
Vera Vital’evna Selivanovskikh. Docent of the department of PC software of the Cherepovetsk State University. Finished postgraduate studies at the Cherepovetsk
State University on specialty “Solid-State Physics” in 2000 and began to study the problem of the optic-electronic control
over the quality of metallurgical industry products. Defended a Ph.D. thesis on specialty 05.13.06 “Automation and Management
of Technological Processes and Productions” in 2007. Author of more than 30 scientific and teaching works, including 1 monograph,
7 articles, of which 2 were published in reviewed journals, 13 theses of reports. Took part in the scientific and technical
conferences in Moscow, Cherepovetsk, Kursk, Tambov, Vologda, Tula, Yoshkar Ola.
Oksana Georgievna Ganicheva. Docent of the department of PC software of the Cherepovetsk State University. Finished postgraduate studies at the Cherepovetsk
State University and defended a Ph.D. thesis on specialty 05.13.06 “Automation and Management of Technological Processes and
Productions” in 2007. Circle of scientific interests: the development and perfecting of methods for the optic-electronic control
over the quality of metallurgical industry products. Author of more than 30 scientific and teaching works, including 1 monograph,
7 articles, of which 2 were published in reviewed journals, 10 theses of reports. Took part in the scientific and technical
conferences in Cherepovetsk, Kursk, Vologda, Tula, Yoshkar Ola. 相似文献
920.
We consider the problem of tracking a “smart” target. That is, a target that is aware it is being tracked and modifies its behaviour accordingly. To track such targets effectively it is necessary to modify the behaviour of the tracking sensor in response to the target. We consider that the best framework for such a problem is that of a mathematical game. In this paper, we consider an idealised version of this problem that illustrates some of the issues that can occur when attempting to track a smart target and the utility of a game theoretic framework. 相似文献