全文获取类型
收费全文 | 25610篇 |
免费 | 2857篇 |
国内免费 | 1884篇 |
专业分类
电工技术 | 2441篇 |
技术理论 | 1篇 |
综合类 | 3253篇 |
化学工业 | 1417篇 |
金属工艺 | 1291篇 |
机械仪表 | 3923篇 |
建筑科学 | 943篇 |
矿业工程 | 610篇 |
能源动力 | 370篇 |
轻工业 | 385篇 |
水利工程 | 341篇 |
石油天然气 | 484篇 |
武器工业 | 620篇 |
无线电 | 4783篇 |
一般工业技术 | 2919篇 |
冶金工业 | 872篇 |
原子能技术 | 191篇 |
自动化技术 | 5507篇 |
出版年
2024年 | 86篇 |
2023年 | 319篇 |
2022年 | 534篇 |
2021年 | 592篇 |
2020年 | 710篇 |
2019年 | 601篇 |
2018年 | 632篇 |
2017年 | 884篇 |
2016年 | 995篇 |
2015年 | 1116篇 |
2014年 | 1497篇 |
2013年 | 1453篇 |
2012年 | 1954篇 |
2011年 | 1986篇 |
2010年 | 1492篇 |
2009年 | 1560篇 |
2008年 | 1575篇 |
2007年 | 1926篇 |
2006年 | 1720篇 |
2005年 | 1382篇 |
2004年 | 1124篇 |
2003年 | 1071篇 |
2002年 | 848篇 |
2001年 | 737篇 |
2000年 | 622篇 |
1999年 | 506篇 |
1998年 | 393篇 |
1997年 | 363篇 |
1996年 | 299篇 |
1995年 | 264篇 |
1994年 | 220篇 |
1993年 | 161篇 |
1992年 | 123篇 |
1991年 | 97篇 |
1990年 | 82篇 |
1989年 | 85篇 |
1988年 | 70篇 |
1987年 | 36篇 |
1986年 | 17篇 |
1985年 | 37篇 |
1984年 | 29篇 |
1983年 | 22篇 |
1982年 | 20篇 |
1981年 | 17篇 |
1980年 | 11篇 |
1979年 | 9篇 |
1977年 | 10篇 |
1964年 | 5篇 |
1956年 | 8篇 |
1955年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 361 毫秒
141.
用WAXD和FT-IR对高温超高压处理前后的HDPE进行了研究。发现经5.0GPa的高压处理或200℃下4.0GPa的高压同时处理后的HDPE分子链的化学结构未发生变化。HDPE晶体中(200)面与(110)面衍射峰的峰高比(γ)随着压力的升高而增大,表明HDPE分子链在超高压作用下发生了取向排列,且升高温度更有利于这种取向排列,但当压力增大至5.0GPa及温度升高至200℃时,γ反而大幅度下降。 相似文献
142.
143.
Akira Ishizaki Kazuhiko Takasaki Shoji Shimomura Kouichi Masaki Kanji Kitazawa 《Electrical Engineering in Japan》1996,116(5):128-137
Although brushless resolvers have been used widely as angular position transducers, they are expensive due to their intricate construction, involving a rotary transformer to supply the exciting coils wound on the rotor poles with the current. It is shown theoretically in this paper that the resolver without rotary transformer or brushes can be realized by simple construction, which consists of the stator core with both 4-poles exciting windings and 2-poles output ones and the rotor core carrying no windings. In this resolver the rotor core has minimum gap at one side and a maximum gap at another side of the diameter. It is characterized by an outer surface form that makes the fluctuation part of gap permeance very in proportion to cos θ, where θ represents the angular position of a point in the air gap with respect to the origin on the rotor, the point of minimum air gap. The method determining the rotor form to embody the aforementioned gap permeance variation is also shown. It has been confirmed not only by simulation but also experiment that the 2-phase output voltages of a model designed based on the theory have sinusoidal waveforms with very small harmonic contents. Moreover, the rotor position detected by processing the output voltages through the conventional resolver/digital converter was within acceptable engineering accuracy. 相似文献
144.
145.
本文考虑了数性双曲方程的离散Galerkin方法。如果精确到光滑的并且同是几乎均匀的,证明了对于分层常数元的最优的和超收敛的误差限。 相似文献
146.
通过分析锚索测力计因受力状态不同而带来的系统误差,提出了测力计实测锚固力的修正方法及部分测力计传感器失效后延续锚固力测值的计算方法. 相似文献
147.
M. Nicolaidis 《Journal of Electronic Testing》1991,1(4):257-273
It has been noted by several authors that the classical stuck-at logical fault model might not be an appropriate representation of certain real failures occurring in integrated circuits. Shorts are an important class of such faults. This article gives a detailed analysis of the effects of shorts in self-checking circuits and proposes techniques for dealing with them. More precisely, we show that, unlike other faults such as stuck-at, stuck-on, and stuck-open—which produce only single errors in the place they occur—shorts can produce double errors on the two shorted lines. In particular, feedback shorts can produce double errors on the two shorted lines. The double error is unidirectional for some feedback shorts and non-unidirectional for some others. Furthermore, in some technologies (e.g., CMOS), non-feedback shorts can also produce double non-unidirectional errors. We also show that unlike stuck-at, stuck-on, and stuck-open faults, redundant shorts can destroy the SFS property. Then we propose several techniques for coping with these problems and we illustrate the results by circuit implementation examples.The present study is given for NMOS and CMOS circuits but we show that it is valid for any other technology. 相似文献
148.
149.
Kevin Burns 《Information Sciences》2006,176(11):1570-1589
Bayesian inference provides a formal framework for assessing the odds of hypotheses in light of evidence. This makes Bayesian inference applicable to a wide range of diagnostic challenges in the field of chance discovery, including the problem of disputed authorship that arises in electronic commerce, counter-terrorism and other forensic applications. For example, when two documents are so similar that one is likely to be a hoax written from the other, the question is: Which document is most likely the source and which document is most likely the hoax? Here I review a Bayesian study of disputed authorship performed by a biblical scholar, and I show that the scholar makes critical errors with respect to several issues, namely: Causal Basis, Likelihood Judgment and Conditional Dependency. The scholar’s errors are important because they have a large effect on his conclusions and because similar errors often occur when people, both experts and novices, are faced with the challenges of Bayesian inference. As a practical solution, I introduce a graphical system designed to help prevent the observed errors. I discuss how this decision support system applies more generally to any problem of Bayesian inference, and how it differs from the graphical models of Bayesian Networks. 相似文献
150.
Journal of Electronic Materials - Low pressure chemical vapor deposition (LPCVD) of tungsten (W) by SiH4 reduction of WF6 on Si(100) surfaces was studied in a single-wafer, cold-wall reactor over a... 相似文献