全文获取类型
收费全文 | 130485篇 |
免费 | 25407篇 |
国内免费 | 4529篇 |
专业分类
电工技术 | 9989篇 |
技术理论 | 3篇 |
综合类 | 7382篇 |
化学工业 | 27145篇 |
金属工艺 | 3949篇 |
机械仪表 | 7123篇 |
建筑科学 | 16560篇 |
矿业工程 | 2994篇 |
能源动力 | 4018篇 |
轻工业 | 10774篇 |
水利工程 | 4298篇 |
石油天然气 | 4544篇 |
武器工业 | 1569篇 |
无线电 | 15493篇 |
一般工业技术 | 22974篇 |
冶金工业 | 3702篇 |
原子能技术 | 972篇 |
自动化技术 | 16932篇 |
出版年
2024年 | 282篇 |
2023年 | 841篇 |
2022年 | 1753篇 |
2021年 | 2458篇 |
2020年 | 5190篇 |
2019年 | 7291篇 |
2018年 | 6696篇 |
2017年 | 7900篇 |
2016年 | 7922篇 |
2015年 | 7962篇 |
2014年 | 9795篇 |
2013年 | 9636篇 |
2012年 | 10079篇 |
2011年 | 9986篇 |
2010年 | 7965篇 |
2009年 | 7510篇 |
2008年 | 7115篇 |
2007年 | 7737篇 |
2006年 | 7137篇 |
2005年 | 6044篇 |
2004年 | 5270篇 |
2003年 | 4717篇 |
2002年 | 4228篇 |
2001年 | 3597篇 |
2000年 | 2997篇 |
1999年 | 2125篇 |
1998年 | 1106篇 |
1997年 | 856篇 |
1996年 | 824篇 |
1995年 | 644篇 |
1994年 | 489篇 |
1993年 | 391篇 |
1992年 | 343篇 |
1991年 | 229篇 |
1990年 | 219篇 |
1989年 | 164篇 |
1988年 | 125篇 |
1987年 | 74篇 |
1986年 | 74篇 |
1985年 | 40篇 |
1984年 | 41篇 |
1981年 | 32篇 |
1980年 | 68篇 |
1979年 | 53篇 |
1965年 | 27篇 |
1964年 | 36篇 |
1959年 | 33篇 |
1958年 | 25篇 |
1956年 | 29篇 |
1955年 | 32篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
81.
Responds to the comments by J. J. Kramer (see record 1990-58925-001) on the current author's original article (see record 1986-19878-001), in which Matarazzo contends that computerized clinical psychological test interpretations offer considerable potential for improving the work of health service providers. However, cost additions associated with this technology have increased the probabilities that legislative, judicial, and administrative restrictions and sanctions will be imposed. Here, Matarazzo notes that he finds nothing in Kramer's comments that is inconsistent with the opinions that Matarazzo himself offered. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
82.
介绍了夹杂物的来源,包括内生夹杂和外来夹杂,着重于二次氧化产物、卷渣、内衬侵蚀.同时介绍了鄂钢电炉厂在冶炼和连铸过程中控制夹杂物的操作实践. 相似文献
83.
In various medium‐to‐large‐scale fire test equipments like the ISO room corner test (RC), and more recently, the single burning item test (SBI) the mass flow rate measurement of the combustion gases plays a key role in the determination of the heat‐release rate and smoke‐production rate. With the knowledge of the velocity profile and the temperature of the flow, the mass flow rate is obtained by measuring the velocity on the axis of the duct. This is done by means of a bi‐directional probe based on the pitot principle. However, due to the variation of the mean temperature and the temperature gradient in any cross section of the duct, introduced by ever changing combustion gas temperatures, the velocity nor the density profile are constant in time. This paper examines the resulting uncertainty on the mass flow rate. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
84.
Shunsuke Ohashi 《Electrical Engineering in Japan》2005,150(1):71-77
Magnetic bearing using pinning force of a permanent magnet and a high‐temperature superconductor has been developed. Additional permanent magnet is introduced to increase the levitation force of the magnetic bearing. In this hybrid magnetic bearing system, levitation force is mainly given by the repulsive force of the permanent magnets, and stability for the lateral direction is given by pinning force of the superconductor. The experimental device is developed. A ring‐type superconductor and a bulk one are examined. Levitation characteristics of the hybrid magnetic bearing are measured. The bulk superconductor shows better characteristics of both levitation and lateral stability than the ring one. Levitation force of the hybrid system becomes about twice as large as that of the nonhybrid one. Although, the repulsive force of the permanent magnet decreases the lateral stability of the system, its influence becomes small by choosing an adequate position of the permanent magnets and the superconductor. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(1): 71–77, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10350 相似文献
85.
Kotaro Matsuuchi Tadashi Fukami Nobuyuki Naoe Ryoichi Hanaoka Shinzo Takata Toshio Miyamoto 《Electrical Engineering in Japan》2005,150(2):43-49
This paper presents a method of predicting the steady‐state performance of a new hybrid‐excitation synchronous machine (HESM) theoretically. The field pole of this HESM is axially divided into two parts; one is an excitation part and the other a permanent‐magnet (PM) part. A nonlinear equivalent circuit, which can include the saliency of the rotor and the magnetic saturation due to the iron core, is derived. Based on this equivalent circuit, the steady‐state performance of the HESM is calculated, and the results are confirmed through experiments. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 43–49, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20033 相似文献
86.
Siba Prasada Panigrahi Santanu Kumar Nayak Sasmita Kumari Padhy 《International Journal of Adaptive Control and Signal Processing》2008,22(7):705-716
This paper presents a neuro‐fuzzy network (NFN) where all its parameters can be tuned simultaneously using genetic algorithms (GAs). The approach combines the merits of fuzzy logic theory, neural networks and GAs. The proposed NFN does not require a priori knowledge about the system and eliminates the need for complicated design steps such as manual tuning of input–output membership functions, and selection of fuzzy rule base. Although, only conventional GAs have been used, convergence results are very encouraging. A well‐known numerical example derived from literature is used to evaluate and compare the performance of the network with other equalizing approaches. Simulation results show that the proposed neuro‐fuzzy controller, all parameters of which have been tuned simultaneously using GAs, offers advantages over existing equalizers and has improved performance. From the perspective of application and implementation, this paper is very interesting as it provides a new method for performing blind equalization. The main contribution of this paper is the use of learning algorithms to train a feed‐forward neural network for M‐ary QAM and PSK signals. This paper also provides a platform for researchers of the area for further development. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
87.
阐述静态电子轨道衡诸多优点;工作原理、允许误差及误差分配;轨道衡的结构组成部分、解析各部分的工作特性及技术指标要求;合理选配及推荐实例. 相似文献
88.
本文在浅埋地下建筑风冷热泵空调系统围护结构传热动态模拟的基础上,通过对南京市太园地下旅社围护结构传热的实时测试,验证动态传热模型及计算机模拟方法的可行性和正确性,为浅埋地下建筑风冷热泵空调系统的装机容量、节能指标和设计计算提供一定的理论依据。 相似文献
89.
90.
Ashraf Ayoub 《Computers & Structures》2003,81(7):411-421
This paper presents an inelastic element for the analysis of beams on foundations. The element is derived from a two-field mixed formulation with independent approximation of forces and displacements. The state determination algorithm for the implementation of the element in a general purpose nonlinear finite element analysis program is presented and its stability characteristics are discussed. Numerical studies are performed to compare the model with the classical displacement formulation. The studies confirm the superiority of the proposed model in describing the inelastic behavior of beams on foundations. 相似文献