全文获取类型
收费全文 | 53721篇 |
免费 | 5409篇 |
国内免费 | 4182篇 |
学科分类
工业技术 | 63312篇 |
出版年
2024年 | 192篇 |
2023年 | 643篇 |
2022年 | 1151篇 |
2021年 | 1281篇 |
2020年 | 1404篇 |
2019年 | 1219篇 |
2018年 | 1251篇 |
2017年 | 1499篇 |
2016年 | 1704篇 |
2015年 | 1766篇 |
2014年 | 3433篇 |
2013年 | 3362篇 |
2012年 | 3747篇 |
2011年 | 3910篇 |
2010年 | 3145篇 |
2009年 | 3579篇 |
2008年 | 3540篇 |
2007年 | 4286篇 |
2006年 | 3591篇 |
2005年 | 3058篇 |
2004年 | 2572篇 |
2003年 | 2303篇 |
2002年 | 1848篇 |
2001年 | 1511篇 |
2000年 | 1303篇 |
1999年 | 1071篇 |
1998年 | 833篇 |
1997年 | 697篇 |
1996年 | 651篇 |
1995年 | 556篇 |
1994年 | 467篇 |
1993年 | 321篇 |
1992年 | 288篇 |
1991年 | 237篇 |
1990年 | 222篇 |
1989年 | 192篇 |
1988年 | 127篇 |
1987年 | 76篇 |
1986年 | 38篇 |
1985年 | 42篇 |
1984年 | 33篇 |
1983年 | 42篇 |
1982年 | 25篇 |
1981年 | 14篇 |
1980年 | 16篇 |
1979年 | 12篇 |
1978年 | 9篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
This paper presents an application of digital signal processing to data acquired by the radio imaging method (RIM) that was adopted to measure moisture distribution inside the human body. RIM was originally developed for the mining industry; we are applying the method to a biomedical measurement because of its simplicity, economy, and safety. When a two‐dimensional image was constructed from the measured data, the method provided insufficient resolution because the wavelength of the measurement medium, a weak electromagnetic wave in a VHF band, was longer than human tissues. We built and measured a phantom, a model simulating the human body, consisting of two water tanks representing large internal organs. A digital equalizer was applied to the measured values as a weight function, and images were reconstructed that corresponded to the original shape of the two water tanks. As a result, a two‐dimensional image containing two individual peaks corresponding to the original two small water tanks was constructed. The result suggests the method was applicable to biomedical measurement by the assistance of digital signal processing. This technique may be applicable to home‐based medical care and other situations in which safety, simplicity, and economy are important. 相似文献
62.
Madden Gregory J.; Begotka Andrea M.; Raiff Bethany R.; Kastern Lana L. 《Canadian Metallurgical Quarterly》2003,11(2):139
The degree to which real and hypothetical rewards were discounted across delays ranging from 6 hr to 1 year was explored in a within-subjects design. An adjusting-amounts procedure was used to estimate the subjective value of real and hypothetical rewards at each delay. A hyperbolic discounting function provided a significantly better fit to individual participants' preferences than did an exponential function. No significant effect of reward type on degree of hyperbolic discounting or area under the discounting curves was detected. These findings offer some support for the validity of using hypothetical rewards to estimate discounting rates in substance-abusing and other populations, but caution is suggested because this support is gleaned from a failure to detect an effect of reward type. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
63.
转炉合金最小成本控制模型 总被引:8,自引:1,他引:7
介绍了基于合金最小成本的转炉炼钢钢水成分调整模型工应用于宝钢炼钢在线生产控制的情况。模型给出了在满足目标成分等工艺要求下,成本最小的合金投入组合及合金投入量;计算了合金加入钢包后引起钢水温度、重量等的变化,为降低生产成本(合金投入),提高出钢成分控制精度提供了有效的途径。 相似文献
64.
基于PSOS的TM1300应用系统中的BSP研究 总被引:1,自引:0,他引:1
通过在应用软件与板级支持包BSP之间加一层库函数的方法较好地解决了应用程序与板级支持包函数间的通信问题,减少了板级支持包函数的维护复杂度,从而为嵌入式系统板级支持包的实现提供了一个有价值的思路。 相似文献
65.
随着设备高速化的日益发展,传统的螺杆设计方法及相应的供送特性评价体系已显落后。参照蜗型凸轮动力学性能的评价方法,建立了高速供送螺杆的动态性能评价体系,为高速化供送螺杆的设计提供了性能参照指标。 相似文献
66.
论述了参数设计法在铝电解电容器设计开发阶段的应用。文中阐明了铝电解电容器的主要质量特性(损耗因子、电容量)及芯包外径的参数设计原理,并建立了归一化函数作为优选设计方案的判据。实例证明在铝电解电容器的设计过程中应用参数设计法以减小产品质量特性变异是有效的。 相似文献
67.
68.
The boundary knot method (BKM) of very recent origin is an inherently meshless, integration‐free, boundary‐type, radial basis function collocation technique for the numerical discretization of general partial differential equation systems. Unlike the method of fundamental solutions, the use of non‐singular general solution in the BKM avoids the unnecessary requirement of constructing a controversial artificial boundary outside the physical domain. The purpose of this paper is to extend the BKM to solve 2D Helmholtz and convection–diffusion problems under rather complicated irregular geometry. The method is also first applied to 3D problems. Numerical experiments validate that the BKM can produce highly accurate solutions using a relatively small number of knots. For inhomogeneous cases, some inner knots are found necessary to guarantee accuracy and stability. The stability and convergence of the BKM are numerically illustrated and the completeness issue is also discussed. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
69.
70.
本文从当前工段成本管理的形势出发 ,阐述了实施“一二三”工段成本管理法的必要性、主要内容及实施效果。 相似文献