全文获取类型
收费全文 | 9447篇 |
免费 | 1207篇 |
国内免费 | 912篇 |
专业分类
电工技术 | 1273篇 |
综合类 | 859篇 |
化学工业 | 888篇 |
金属工艺 | 371篇 |
机械仪表 | 800篇 |
建筑科学 | 604篇 |
矿业工程 | 215篇 |
能源动力 | 302篇 |
轻工业 | 331篇 |
水利工程 | 352篇 |
石油天然气 | 851篇 |
武器工业 | 435篇 |
无线电 | 1113篇 |
一般工业技术 | 1445篇 |
冶金工业 | 326篇 |
原子能技术 | 279篇 |
自动化技术 | 1122篇 |
出版年
2024年 | 45篇 |
2023年 | 167篇 |
2022年 | 289篇 |
2021年 | 320篇 |
2020年 | 397篇 |
2019年 | 366篇 |
2018年 | 355篇 |
2017年 | 433篇 |
2016年 | 456篇 |
2015年 | 459篇 |
2014年 | 599篇 |
2013年 | 739篇 |
2012年 | 641篇 |
2011年 | 744篇 |
2010年 | 542篇 |
2009年 | 598篇 |
2008年 | 504篇 |
2007年 | 570篇 |
2006年 | 569篇 |
2005年 | 440篇 |
2004年 | 385篇 |
2003年 | 302篇 |
2002年 | 250篇 |
2001年 | 204篇 |
2000年 | 206篇 |
1999年 | 143篇 |
1998年 | 128篇 |
1997年 | 119篇 |
1996年 | 102篇 |
1995年 | 84篇 |
1994年 | 86篇 |
1993年 | 51篇 |
1992年 | 49篇 |
1991年 | 43篇 |
1990年 | 40篇 |
1989年 | 29篇 |
1988年 | 19篇 |
1987年 | 21篇 |
1986年 | 9篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1966年 | 4篇 |
1963年 | 4篇 |
1959年 | 4篇 |
1956年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 4 毫秒
11.
双波段比色辐射温度计的波长选择 总被引:6,自引:2,他引:4
张友山 《红外与毫米波学报》1993,12(4):324-328
通过对比色测温法灵敏度温区特性和波比数判据的分析,讨论了比色波长的匹配原理,试图解决选择比色波长的理论依据。 相似文献
12.
榆树林油田砂岩储层敏感性研究 总被引:16,自引:10,他引:6
榆树林油田储层粘土矿物含量较高,各种注入条件和施工条件都会对该储层造成相应的伤害,应采取相应的防护措施,为防止速敏的发生,储层的注水速度应控制在临界流速(1.0mL/min)以下,在油井转注时,可先注入1.09PV的含粘土稳定剂的进行处理,以提高产量或注入量,注入阴离子表面活性剂配置的活性水再注入地层水,不能增加地层水的渗透率,该项试验研究对指导榆树林油田的开发具有重要的意义。 相似文献
13.
Sensitivity analysis is used to show how uncertainties in basic factors, such as heat transfer, pressure drop, compressor efficiency, and thermophysical properties, influence the result of heat pump cycle performance estimations. By comparing the results of this analysis with uncertainty levels of estimations and experimental determinations, it is established to what extent improvements in accuracy are needed. The investigation was carried out for several different applications and, as working fluids, both pure substances and non-azeotropic mixtures were examined. It was found that evaporation heat transfer and compressor efficiency are two areas where improvements are needed. It is also shown that estimates using very accurate, substance-specific, equations of state differ from those using more general types by up to 1 % for COP and 2% for capacity. 相似文献
14.
Josef Skrzypek 《Journal of Intelligent Manufacturing》1993,4(1):67-77
Computer vision algorithms for inspection or pick-and-place operations often depend on spatially uniform illumination of a workplace. This necessitates expensive lighting fixtures. To discount effects of uneven illumination we designed and tested a neural network that can adaptively control light sensitivity at the photosensor level. Our neural network architecture consists of multiple layers with hexagonally arranged nodes. All nodes have partially overlapping receptive fields of different spatial frequencies. Feedforward connections are excitatory while feedback pathways subserve lateral inhibition. The outputs of these nodes are combined so as to maximize the signal-to-noise ratio while constantly resetting thresholds to maintain high sensitivity. Our connectionist architecture can account for many characteristics attributed to the lightness constancy phenomenon observed in biological systems. The results suggest that our module maintains high sensitivity over the whole domain of intensities without interfering with transmission of visual information embedded in spatial discontinuities of intensity. 相似文献
15.
A novel approach is presented to calculate the sensitivities of the scattering parameters of microwave filters obtained with the full‐wave mode‐matching (MM) technique. Using only the MM simulation of the original network, the sensitivities of the scattering parameters with respect to all designable parameters are obtained. The adjoint network method (ANM) is applied to the generalized scattering matrices of the different filter components. This guarantees good accuracy of the calculated sensitivities. The implementation details are discussed for N‐resonator ridge waveguide filters. Excellent agreement is obtained between the sensitivities calculated using ANM and those obtained using the expensive central differences. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006. 相似文献
16.
In this paper an H∞ optimal, robust flight control system design for a supersonic aircraft has been described. Separate controllers are designed for longitudinal and lateral motions. A general two-degrees-of-freedom controller is proposed, where feedback control is designed for robust performance augmentation, while a series compensator is used to ensure that requisite handling qualities. Three alternative methods to achieve performance robustness have been discussed. The results obtained are very encouraging. It is hoped that this will equip the flight control engineers with an alternative to the conventional methods. 相似文献
17.
18.
泡沫铝的动态压缩性能和吸能性研究 总被引:9,自引:0,他引:9
通过测量泡沫铝在动态和准静态压缩条件下的应力 -应变曲线 ,研究了泡沫铝的准静态和动态压缩行为以及不同应变条件下的吸能性 ,并对其应变率效应进行了分析。结果表明 ,在高应变速率和准静态压缩下 ,泡沫铝的σ -ε曲线均表现出弹性变形段、平缓段和密实段三阶段特征 ;泡沫铝的压缩性能具有明显的应变速率敏感性 ,随应变速率的提高 ,流动应力上升 ,吸能性升高 相似文献
19.
20.
基于MOCCⅡ多功能滤波器的设计 总被引:8,自引:5,他引:3
本文简要介绍了Mulitple-output CCⅡ(简称MOCCⅡ)器件的电路特性,提出了一个新颖的基于MOCCⅡ多功能滤波器的电路。该电路可同时实现一阶低通以及二阶低通、高通、带阻、全通和带通等输出。经分析,该电路具有很低的灵敏度。电路中所有RC元件均接地,便于集成等优点。 相似文献