全文获取类型
收费全文 | 67753篇 |
免费 | 9680篇 |
国内免费 | 7374篇 |
专业分类
电工技术 | 5642篇 |
技术理论 | 9篇 |
综合类 | 7183篇 |
化学工业 | 1890篇 |
金属工艺 | 1012篇 |
机械仪表 | 4252篇 |
建筑科学 | 2382篇 |
矿业工程 | 1679篇 |
能源动力 | 914篇 |
轻工业 | 980篇 |
水利工程 | 1402篇 |
石油天然气 | 3002篇 |
武器工业 | 1004篇 |
无线电 | 11092篇 |
一般工业技术 | 3555篇 |
冶金工业 | 1435篇 |
原子能技术 | 1332篇 |
自动化技术 | 36042篇 |
出版年
2024年 | 508篇 |
2023年 | 1330篇 |
2022年 | 2609篇 |
2021年 | 3000篇 |
2020年 | 2910篇 |
2019年 | 2235篇 |
2018年 | 1962篇 |
2017年 | 2352篇 |
2016年 | 2649篇 |
2015年 | 3012篇 |
2014年 | 4691篇 |
2013年 | 4308篇 |
2012年 | 5007篇 |
2011年 | 5327篇 |
2010年 | 4118篇 |
2009年 | 4110篇 |
2008年 | 4571篇 |
2007年 | 5129篇 |
2006年 | 4297篇 |
2005年 | 3930篇 |
2004年 | 3320篇 |
2003年 | 2781篇 |
2002年 | 2129篇 |
2001年 | 1598篇 |
2000年 | 1351篇 |
1999年 | 1008篇 |
1998年 | 776篇 |
1997年 | 660篇 |
1996年 | 527篇 |
1995年 | 464篇 |
1994年 | 382篇 |
1993年 | 280篇 |
1992年 | 194篇 |
1991年 | 195篇 |
1990年 | 175篇 |
1989年 | 122篇 |
1988年 | 89篇 |
1987年 | 82篇 |
1986年 | 79篇 |
1985年 | 93篇 |
1984年 | 61篇 |
1983年 | 73篇 |
1982年 | 80篇 |
1981年 | 53篇 |
1980年 | 22篇 |
1979年 | 34篇 |
1978年 | 13篇 |
1977年 | 20篇 |
1976年 | 13篇 |
1959年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
ARAM·ARIES SPM-Lite便携式遥测地震数据采集系统是加拿大GEO-X公司在2002年下半年推出的全新小型便携式地震数据采集系统。该仪器运用了当今最先进的计算机制造技术、网络化技术和微电子技术,除继承了ARAM-ARIES地震数据采集系统所有功能和技术外,它还简化了硬件结构,使体积更小,重量更轻,功能性更强。更加适应地矿、煤田、丛林和山区进行地震勘探。 相似文献
32.
介绍一种基于快速平台测井要求的多通道核能谱测井仪设计方案。复杂可编程逻辑器件的应用使仪器功能增强,规模减小。该系统可对岩性密度长短源距脉冲信号、自然γ能谱脉冲信号进行多道脉冲幅度分析,并对补偿中子测井信号及井下多路常规模拟信号、脉冲信号进行数字化采集。数据传输采用曼彻斯特编码,传输方式可选择20kB/s半双工(兼容Atlas 3508)或下行20kB/s、上行41.66或93.75kB/s全双工方式(兼容Atlas WTS),适应挂接到不同测井系统的需要。 相似文献
33.
The requirements on an object-oriented DBMS for management of information in a large, complex enterprise are presented. These requirements aid in the achievement of an environment characterized by data sharing, open architectures, application and data portability, and assurance of data integrity. They were defined from the point of view of a user of the DBMS; therefore they describe the expected functionality of the DBMS and do not specify the method of implementation to achieve this functionality. They encompass requirements on the data model, query and data manipulation languages, the system architecure, interfaces to the system, change management, and transaction management. 相似文献
34.
根据某雷达系统对测量信号的快速传输要求,提出采用滑动帧的处理方法并在FPGA中实现,克服了传统帧处理难以满足快速传输要求的不足。阐述了滑动帧结构的构造思想,详述了滑动帧结构的特点及具体功能模块的实现。根据实际应用需求构造了滑动帧结构处理器,试验和应用结果表明设计可行有效,能充分满足实时数据传输的要求。 相似文献
35.
The influence of raw material characteristics on the industrial pelletizing process and pellet quality 总被引:1,自引:0,他引:1
Mehrdad Arshadi Rolf Gref Paul Geladi Sten-Axel Dahlqvist Torbjörn Lestander 《Fuel Processing Technology》2008
Industrial pelletizing of sawdust was carried out as a designed experiment in the factors: sawdust moisture content, fractions of fresh pine, stored pine and spruce. The process parameters and response variables were energy consumption, pellet flow rate, pellet bulk density, durability and moisture content. The final data consisted of twelve industrial scale runs. Because of the many response variables, data evaluation was by principal component analysis of a 12 × 9 data matrix. The two principal component model showed a clustering of samples, with a good reproducibility of the center points. It also showed a positive correlation of energy consumption, bulk density and durability all negatively correlated to flow rate and moisture content. The stored pine was more related to high durability and bulk density. The role of the spruce fraction was unclear. The design matrix, augmented with the process parameters was a 12 × 6 matrix. Partial least squares regression showed excellent results for pellet moisture content and bulk density. The model for durability was promising. A 12 × 21 data matrix of fatty- and resin acid concentrations measured by GC–MS showed the differences between fresh and stored pine very clearly. The influence of the spruce fraction was less clear. However, the influence of the fatty- and resin acids on the pelletizing process could not be confirmed, indicating that other differences between fresh and stored pine sawdust have to be investigated. This work shows that it is possible to design the pelletizing process for moderate energy consumption and high pellet quality. 相似文献
36.
说明了在异步串行通信(RS-232)的工作方式下,对所接收的数据进行接收、处理,丢弃乱码,并进行保存的可靠方法,并给出了相关的VC 语言程序. 相似文献
37.
Cathy Lawson Douglas C. Montgomery 《Quality and Reliability Engineering International》2006,22(8):971-984
Variation exists in all processes. Significant work has been done to identify and remove sources of variation in manufacturing processes resulting in large returns for companies. However, business process optimization is an area that has a large potential return for a company. Business processes can be difficult to optimize due to the nature of the output variables associated with them. Business processes tend to have output variables that are binary, nominal or ordinal. Examples of these types of output include whether a particular event occurred, a customer's color preference for a new product and survey questions that assess the extent of the survey respondent's agreement with a particular statement. Output variables that are binary, nominal or ordinal cannot be modeled using ordinary least‐squares regression. Logistic regression is a method used to model data where the output is binary, nominal or ordinal. This article provides a review of logistic regression and demonstrates its use in modeling data from a business process involving customer feedback. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
38.
39.
Shu‐Li Sun Jing Ma Nan Lv 《International Journal of Adaptive Control and Signal Processing》2008,22(10):932-948
Based on the optimal fusion estimation algorithm weighted by scalars in the linear minimum variance sense, a distributed optimal fusion Kalman filter weighted by scalars is presented for discrete‐time stochastic singular systems with multiple sensors and correlated noises. A cross‐covariance matrix of filtering errors between any two sensors is derived. When the noise statistical information is unknown, a distributed identification approach is presented based on correlation functions and the weighted average method. Further, a distributed self‐tuning fusion filter is given, which includes two stage fusions where the first‐stage fusion is used to identify the noise covariance and the second‐stage fusion is used to obtain the fusion state filter. A simulation verifies the effectiveness of the proposed algorithm. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
40.
介绍一种针对正、余弦旋转变压器—数字转换器(RDC)模块,用复杂可编程逻辑器件(CPLD)技术实现伺服轴角编码电路设计的方案。分析了轴角编码器系统中14XSZ系列旋转变压器—数字转换器的原理、轴角粗精组合原理及轴角纠错原理。详细介绍了CPLD的内部功能电路、CPLD轴角粗精组合和纠错实现电路,以及CPLD的工作时序图。提出了利用CPLD实现轴角粗精组合处理的方案,并通过了实际系统运行的考验,证明该方案可行。 相似文献