全文获取类型
收费全文 | 4921篇 |
免费 | 341篇 |
国内免费 | 172篇 |
学科分类
工业技术 | 5434篇 |
出版年
2024年 | 23篇 |
2023年 | 82篇 |
2022年 | 148篇 |
2021年 | 196篇 |
2020年 | 115篇 |
2019年 | 122篇 |
2018年 | 143篇 |
2017年 | 152篇 |
2016年 | 119篇 |
2015年 | 180篇 |
2014年 | 180篇 |
2013年 | 226篇 |
2012年 | 230篇 |
2011年 | 285篇 |
2010年 | 252篇 |
2009年 | 240篇 |
2008年 | 279篇 |
2007年 | 214篇 |
2006年 | 198篇 |
2005年 | 153篇 |
2004年 | 102篇 |
2003年 | 97篇 |
2002年 | 95篇 |
2001年 | 104篇 |
2000年 | 116篇 |
1999年 | 138篇 |
1998年 | 264篇 |
1997年 | 187篇 |
1996年 | 129篇 |
1995年 | 79篇 |
1994年 | 78篇 |
1993年 | 67篇 |
1992年 | 35篇 |
1991年 | 31篇 |
1990年 | 24篇 |
1989年 | 29篇 |
1988年 | 27篇 |
1987年 | 24篇 |
1986年 | 28篇 |
1985年 | 15篇 |
1984年 | 27篇 |
1983年 | 17篇 |
1982年 | 16篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 9篇 |
1978年 | 13篇 |
1977年 | 8篇 |
1976年 | 34篇 |
1956年 | 8篇 |
排序方式: 共有5434条查询结果,搜索用时 0 毫秒
1.
Weiming Shen S.Y.T. Lang Lihui Wang 《IEEE transactions on systems, man and cybernetics. Part C, Applications and reviews》2005,35(3):371-381
Global competition is driving manufacturing companies to change the way they do business. New kinds of shop floor control systems need to be implemented for these companies to respond quickly to changing shop floor environments and customer demands. This paper presents a new concept called iShopFloor-an intelligent shop floor based on the Internet, web, and agent technologies. It focuses on the implementation of distributed intelligence in the manufacturing shop floor. The proposed approach provides the framework for components of a complex control system to work together as a whole rather than as a disjoint set. It encompasses both information architecture and integration methodologies. The paper introduces the basic concept of iShopFloor, a generic system architecture, and system components. It also describes the implementation of eXtensible Markup Language message services in iShopFloor and the application of intelligent agents to distributed manufacturing scheduling. A prototype environment is presented, and some implementation issues are discussed. 相似文献
2.
手工水饺定量给馅机的设计 总被引:1,自引:0,他引:1
手工水饺定量给馅机解决了包制手工水饺的定量给馅问题,保持每个水饺的重量一致稳定。该机采用柱塞泵给馅,气动传动,自动化,高效率,适合工业化生产手工水饺使用。 相似文献
3.
We have fabricated and tested a high-Tc dc-SQUID magnetometer patterned on a YBCO thin film deposited on a SrTiO3 bicrystal substrate. The measurement of noise spectrum at 77 K showed that the magnetometer has a white noise of 333 fT/Hz1/2 without superconducting shield, corresponding to a flux sensitivity of 14.5 μΦ0/Hz1/2. We constructed a test system for eddy current non-destructive evaluation of conducting aluminum plates by using the magnetometer. Flaws over 10 mm below the surface can be clearly identified. By mapping the magnetic field distribution, we can locate the flaw position. The signals caused by flaw were expanded due to the use of double-D type driving coil with a wider central slit. The experimental results confirmed that this test system could operate in a magnetic unshielded environment. 相似文献
4.
Estimation of the log-normal mean 总被引:1,自引:0,他引:1
XH Zhou 《Canadian Metallurgical Quarterly》1998,17(19):2251-2264
The most commonly used estimator for a log-normal mean is the sample mean. In this paper, we show that this estimator can have a large mean square error, even for large samples. Then, we study three main alternative estimators: (i) a uniformly minimum variance unbiased (UMVU) estimator; (ii) a maximum likelihood (ML) estimator; (iii) a conditionally minimal mean square error (MSE) estimator. We find that the conditionally minimal MSE estimator has the smallest mean square error among the four estimators considered here, regardless of the sample size and the skewness of the log-normal population. However, for large samples (n > or = 200), the UMVU estimator, the ML estimator, and the conditionally minimal MSE estimators have very similar mean square errors. Since the ML estimator is the easiest to compute among these three estimators, for large samples we recommend the use of the ML estimator. For small to moderate samples, we recommend the use of the conditionally minimal MSE estimator. 相似文献
5.
6.
K Takayama H Ueno XH Pei Y Nakanishi J Yatsunami N Hara 《Canadian Metallurgical Quarterly》1998,5(3):361-368
Adenovirus mediated transfer of growth-inhibiting molecules, such as p53 shows promise as an effective method of suppressing the growth of cancer cells. As the basis for in vivo studies, we examined transfection efficiency using 15 human lung cancer cell lines that differ in their endogenous p53 status. When infected with an adenovirus expressing bacterial beta-galactosidase, the different cell lines showed different levels of beta-galactosidase activity. We found a correlation between the level of integrin alpha v beta 5, which is thought to be an adherence receptor for adenoviruses, and the expression level of the transferred gene, suggesting that gene expression is largely dependent on the infection efficiency. Growth inhibition was induced in all cell lines tested following infection with an adenovirus containing p53, regardless of the genetic status of their endogenous p53 provided a sufficient amount of p53 protein was expressed. Our results (1) confirm that the examination of the susceptibility of target cancer cells to an adenovirus is important when considering performing adenovirus-mediated gene transfer and for evaluating its therapeutic effects; and (2) suggest that the quantification of integrin alpha v beta 5 may be a good way of predicting the susceptibility of cells to adenoviral vectors. 相似文献
7.
8.
9.
Mesh network resiliency using GMPLS 总被引:4,自引:0,他引:4
Lang J.P. Drake J. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2002,90(9):1559-1564
The generalized multiprotocol label switching (GMPLS) is being developed as the control plane for the evolving photonic network. We describe how GMPLS can be used with mesh networks to provide efficient network resiliency. In particular we examine the key aspects of GMPLS that are used to support protection and restoration. We also study the various protection and restoration techniques, and we highlight the tradeoffs between recovery time and resource redundancy 相似文献
10.
Magnetic induction micromachine-part I: Design and analysis 总被引:1,自引:0,他引:1
Most microscale electric and magnetic machines studied in the last decade lack the power density to support many practical applications. This paper introduces a design for a magnetic induction machine that offers power densities in excess of 200 MW/m/sup 3/ and efficiencies of up to 50%, while providing more than 10 W of mechanical power. This is a substantial performance increase in MEMS electromagnetic machines studied to date. 相似文献