全文获取类型
收费全文 | 37162篇 |
免费 | 5541篇 |
国内免费 | 2255篇 |
专业分类
电工技术 | 10855篇 |
技术理论 | 3篇 |
综合类 | 3243篇 |
化学工业 | 1460篇 |
金属工艺 | 735篇 |
机械仪表 | 3573篇 |
建筑科学 | 3179篇 |
矿业工程 | 3299篇 |
能源动力 | 1187篇 |
轻工业 | 576篇 |
水利工程 | 1481篇 |
石油天然气 | 3126篇 |
武器工业 | 477篇 |
无线电 | 2058篇 |
一般工业技术 | 1702篇 |
冶金工业 | 1285篇 |
原子能技术 | 156篇 |
自动化技术 | 6563篇 |
出版年
2024年 | 290篇 |
2023年 | 617篇 |
2022年 | 1207篇 |
2021年 | 1445篇 |
2020年 | 1598篇 |
2019年 | 1051篇 |
2018年 | 964篇 |
2017年 | 1194篇 |
2016年 | 1323篇 |
2015年 | 1559篇 |
2014年 | 2727篇 |
2013年 | 2047篇 |
2012年 | 3052篇 |
2011年 | 3058篇 |
2010年 | 2328篇 |
2009年 | 2541篇 |
2008年 | 2309篇 |
2007年 | 2697篇 |
2006年 | 2391篇 |
2005年 | 1925篇 |
2004年 | 1651篇 |
2003年 | 1502篇 |
2002年 | 1163篇 |
2001年 | 1003篇 |
2000年 | 786篇 |
1999年 | 660篇 |
1998年 | 404篇 |
1997年 | 324篇 |
1996年 | 278篇 |
1995年 | 246篇 |
1994年 | 137篇 |
1993年 | 118篇 |
1992年 | 92篇 |
1991年 | 79篇 |
1990年 | 56篇 |
1989年 | 34篇 |
1988年 | 26篇 |
1987年 | 15篇 |
1986年 | 12篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 8篇 |
1979年 | 3篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1954年 | 2篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
Machine learning algorithms have been widely used in mine fault diagnosis. The correct selection of the suitable algorithms is the key factor that affects the fault diagnosis. However, the impact of machine learning algorithms on the prediction performance of mine fault diagnosis models has not been fully evaluated. In this study, the windage alteration faults (WAFs) diagnosis models, which are based on K-nearest neighbor algorithm (KNN), multi-layer perceptron (MLP), support vector machine (SVM), and decision tree (DT), are constructed. Furthermore, the applicability of these four algorithms in the WAFs diagnosis is explored by a T-type ventilation network simulation experiment and the field empirical application research of Jinchuan No. 2 mine. The accuracy of the fault location diagnosis for the four models in both networks was 100%. In the simulation experiment, the mean absolute percentage error (MAPE) between the predicted values and the real values of the fault volume of the four models was 0.59%, 97.26%, 123.61%, and 8.78%, respectively. The MAPE for the field empirical application was 3.94%, 52.40%, 25.25%, and 7.15%, respectively. The results of the comprehensive evaluation of the fault location and fault volume diagnosis tests showed that the KNN model is the most suitable algorithm for the WAFs diagnosis, whereas the prediction performance of the DT model was the second-best. This study realizes the intelligent diagnosis of WAFs, and provides technical support for the realization of intelligent ventilation. 相似文献
3.
Vancha Harish Effi Haque Magdalena
miech Hiroaki Taniguchi Sarah Jamieson Devesh Tewari Anupam Bishayee 《International journal of molecular sciences》2021,22(9)
Xanthohumol (XH) is an important prenylated flavonoid that is found within the inflorescence of Humulus lupulus L. (Hop plant). XH is an important ingredient in beer and is considered a significant bioactive agent due to its diverse medicinal applications, which include anti-inflammatory, antimicrobial, antioxidant, immunomodulatory, antiviral, antifungal, antigenotoxic, antiangiogenic, and antimalarial effects as well as strong anticancer activity towards various types of cancer cells. XH acts as a wide ranging chemopreventive and anticancer agent, and its isomer, 8-prenylnaringenin, is a phytoestrogen with strong estrogenic activity. The present review focuses on the bioactivity of XH on various types of cancers and its pharmacokinetics. In this paper, we first highlight, in brief, the history and use of hops and then the chemistry and structure–activity relationship of XH. Lastly, we focus on its prominent effects and mechanisms of action on various cancers and its possible use in cancer prevention and treatment. Considering the limited number of available reviews on this subject, our goal is to provide a complete and detailed understanding of the anticancer effects of XH against different cancers. 相似文献
4.
5.
针对自动飞行控制系统结构复杂、关联部件众多,发生故障时诊断时间长,从而影响飞机运行效率的问题,提出一种基于飞机通信寻址报告系统(ACARS)的远程实时故障诊断方案。首先,分析自动飞行控制系统的故障特点,设计搭建检测滤波器;然后,利用ACARS数据链实时发送的自动飞行控制系统的关键信息进行相关部件的残差计算,并根据残差决策算法进行故障诊断及定位;最后,针对不同故障部件残差间的差异大、决策门限无法统一的缺点,提出基于二次差值的残差决策改进算法,减缓了检测对象的整体变化趋势,降低了随机噪声和干扰的影响,避免了将瞬态故障诊断为系统故障的情况。实验仿真结果表明,基于二次差值的改进残差决策算法避免了多决策门限的复杂性,在采样时间为0.1 s的情况下,故障检测所需时间大约为2 s,故障检测时间大幅降低,有效故障检测率大于90%。 相似文献
6.
一次性医用手套是能够防止人们交叉感染的常用防护用品。随着新冠肺炎疫情在全球范围的迅速蔓延,疫情防控一线以及广大普通民众对一次性医用手套的需求与日俱增,其标准也受到广泛关注。本文对中国国家标准涉及一次性使用医用手套的4项产品标准进行了解读,并分析它们与国外同种产品标准间的对应关系以及重点指标的差异。 相似文献
7.
8.
为了提升高校实验数据处理水平,高校实验室的相关建设工作已经步入正轨,但层出不穷的信息安全问题也向高校实验室计算机网络维护工作提出了新的挑战。文章从现阶段高校实验室计算机网络的相关建设工作出发,简要论述引发网络故障的具体原因,并对其诊断技术进行探讨。 相似文献
9.
One of the major challenges in wireless body area networks (WBANs) is sensor fault detection. This paper reports a method for the precise identification of faulty sensors, which should help users identify true medical conditions and reduce the rate of false alarms, thereby improving the quality of services offered by WBANs. The proposed sensor fault detection (SFD) algorithm is based on Pearson correlation coefficients and simple statistical methods. The proposed method identifies strongly correlated parameters using Pearson correlation coefficients, and the proposed SFD algorithm detects faulty sensors. We validated the proposed SFD algorithm using two datasets from the Multiparameter Intelligent Monitoring in Intensive Care database and compared the results to those of existing methods. The time complexity of the proposed algorithm was also compared to that of existing methods. The proposed algorithm achieved high detection rates and low false alarm rates with accuracies of 97.23% and 93.99% for Dataset 1 and Dataset 2, respectively. 相似文献
10.