全文获取类型
收费全文 | 87712篇 |
免费 | 10879篇 |
国内免费 | 5850篇 |
专业分类
电工技术 | 25295篇 |
技术理论 | 1篇 |
综合类 | 8503篇 |
化学工业 | 8683篇 |
金属工艺 | 4073篇 |
机械仪表 | 4600篇 |
建筑科学 | 6300篇 |
矿业工程 | 2633篇 |
能源动力 | 3496篇 |
轻工业 | 2447篇 |
水利工程 | 2617篇 |
石油天然气 | 3553篇 |
武器工业 | 808篇 |
无线电 | 10324篇 |
一般工业技术 | 6707篇 |
冶金工业 | 3766篇 |
原子能技术 | 1539篇 |
自动化技术 | 9096篇 |
出版年
2024年 | 430篇 |
2023年 | 1316篇 |
2022年 | 2271篇 |
2021年 | 2851篇 |
2020年 | 3134篇 |
2019年 | 2649篇 |
2018年 | 2553篇 |
2017年 | 3336篇 |
2016年 | 3449篇 |
2015年 | 3859篇 |
2014年 | 5732篇 |
2013年 | 5660篇 |
2012年 | 6579篇 |
2011年 | 7030篇 |
2010年 | 5012篇 |
2009年 | 5445篇 |
2008年 | 5165篇 |
2007年 | 6172篇 |
2006年 | 5528篇 |
2005年 | 4398篇 |
2004年 | 3735篇 |
2003年 | 3152篇 |
2002年 | 2550篇 |
2001年 | 2224篇 |
2000年 | 1887篇 |
1999年 | 1540篇 |
1998年 | 1224篇 |
1997年 | 999篇 |
1996年 | 861篇 |
1995年 | 726篇 |
1994年 | 671篇 |
1993年 | 467篇 |
1992年 | 387篇 |
1991年 | 298篇 |
1990年 | 242篇 |
1989年 | 220篇 |
1988年 | 156篇 |
1987年 | 112篇 |
1986年 | 78篇 |
1985年 | 68篇 |
1984年 | 60篇 |
1983年 | 39篇 |
1982年 | 45篇 |
1981年 | 22篇 |
1980年 | 24篇 |
1979年 | 12篇 |
1977年 | 8篇 |
1975年 | 6篇 |
1959年 | 15篇 |
1951年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Structural health monitoring system based on multi-agent coordination and fusion for large structure
In practical applications of structural health monitoring technology, a large number of distributed sensors are usually adopted to monitor the big dimension structures and different kinds of damage. The monitored structures are usually divided into different sub-structures and monitored by different sensor sets. Under this situation, how to manage the distributed sensor set and fuse different methods to obtain a fast and accurate evaluation result is an important problem to be addressed deeply. In the paper, a multi-agent fusion and coordination system is presented to deal with the damage identification for the strain distribution and joint failure in the large structure. Firstly, the monitoring system is adopted to distributedly monitor two kinds of damages, and it self-judges whether the static load happens in the monitored sub-region, and focuses on the static load on the sub-region boundary to obtain the sensor network information with blackboard model. Then, the improved contract net protocol is used to dynamically distribute the damage evaluation module for monitoring two kinds of damage uninterruptedly. Lastly, a reliable assessment for the whole structure is given by combing various heterogeneous classifiers strengths with voting-based fusion. The proposed multi-agent system is illustrated through a large aerospace aluminum plate structure experiment. The result shows that the method can significantly improve the monitoring performance for the large-scale structure. 相似文献
2.
3.
4.
Private information retrieval(PIR) is an important privacy protection issue of secure multi-party computation, but the PIR protocols based on classical cryptography are vulnerable because of new technologies,such as quantum computing and cloud computing. The quantum private queries(QPQ) protocols available, however, has a high complexity and is inefficient in the face of large database. This paper, based on the QKD technology which is mature now, proposes a novel QPQ protocol utilizing the key dilution and auxiliary parameter. Only N quits are required to be sent in the quantum channel to generate the raw key, then the straight k bits in the raw key are added bitwise to dilute the raw key, and a final key is consequently obtained to encrypt the database. By flexible adjusting of auxiliary parameters θ and k, privacy is secured and the query success ratio is improved. Feasibility and performance analyses indicate that the protocol has a high success ratio in first-trial query and is easy to implement, and that the communication complexity of O(N) is achieved. 相似文献
5.
段潇乐 《湖南工业职业技术学院学报》2015,(1):82-84
本研究检测了直接和间接两种修正性反馈与国内高职理科学生写作水平的关系。本实验持续五周,将150名学习者分为直接反馈组、间接反馈组及控制组,共安排了一次预先测试,,一次即时后测和一次延时后测,并分别对各组进行考察,结果显示两个实验组进步显著,且直接反馈效果最明显。 相似文献
6.
Spinel LiSr0·1Cr0·1Mn1·8O4 was synthesised by high temperature solid state method in order to enhance the electrochemical performance. The LiSr0·1Cr0·1Mn1·8O4 (LSCMO) materials were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical tests. The XRD and SEM studies confirm that LSCMO had spinel crystal structure with a space group of Fd3m, and the particle of LSCMO shows irregular shape. The cyclic voltammetry data illustrated that the heavy current charge–discharge performance of LMO was improved by Sr2+ and Cr3+ doping. The galvanostatic charge–discharge of LSCMO cathode materials was measured at 1, 5, 10 and 20 C. The results indicated that LSCMO improved the capacity retention. 相似文献
7.
8.
Eight datasets of 1-h black carbon (BC) concentrations measured in Warsaw agglomeration (Poland), at urban background and sub-urban sites, and in Racibórz, a small town in Upper Silesia district (regional background site) were analyzed to evaluate BC levels, daily profiles and statistical distributions of concentrations in Central-Eastern European region. The observed mean levels ranged from 1483 ng m−3 in suburban site during summer to 3358 ng m−3 in regional background site in winter. Observed diurnal patterns were bimodal in the locations dominated by traffic emissions, but unimodal, with elevated evening peak in individually heated residential area. Three theoretical frequency distributions were applied to fit analyzed datasets separately. The lognormal distribution was the most appropriate to represent the middle-range values, while the high concentrations were satisfactorily predicted by the type I two-parameter exponential distribution which was used to estimate the return periods of extreme concentrations for winter months. 相似文献
9.
10.
Seong‐Hee Kim 《Quality and Reliability Engineering International》2015,31(6):923-934
We present a distribution‐free tabular cumulative sum chart for monitoring the variability of an autocorrelated process. A quantity known as the asymptotic variance parameter is employed as a measure of the variability, and a distribution‐free tabular cumulative sum chart is applied to variance estimates calculated from batches of nonoverlapping samples. The proposed chart is applicable to a stationary process with a general marginal distribution and a general autocorrelation structure. It also determines control limits analytically without trial‐and‐error simulations. The performance of the proposed chart is tested on stationary processes with both normal and nonnormal marginals with various autocorrelation structures. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献