全文获取类型
收费全文 | 220466篇 |
免费 | 22805篇 |
国内免费 | 13106篇 |
专业分类
电工技术 | 17527篇 |
技术理论 | 8篇 |
综合类 | 17721篇 |
化学工业 | 31700篇 |
金属工艺 | 13502篇 |
机械仪表 | 15016篇 |
建筑科学 | 18213篇 |
矿业工程 | 7348篇 |
能源动力 | 6689篇 |
轻工业 | 16656篇 |
水利工程 | 5355篇 |
石油天然气 | 10989篇 |
武器工业 | 2535篇 |
无线电 | 26370篇 |
一般工业技术 | 23016篇 |
冶金工业 | 9237篇 |
原子能技术 | 2669篇 |
自动化技术 | 31826篇 |
出版年
2024年 | 1101篇 |
2023年 | 3655篇 |
2022年 | 7140篇 |
2021年 | 9816篇 |
2020年 | 7396篇 |
2019年 | 5852篇 |
2018年 | 6532篇 |
2017年 | 7625篇 |
2016年 | 6703篇 |
2015年 | 9834篇 |
2014年 | 12378篇 |
2013年 | 14556篇 |
2012年 | 16946篇 |
2011年 | 17656篇 |
2010年 | 16199篇 |
2009年 | 15303篇 |
2008年 | 14960篇 |
2007年 | 14127篇 |
2006年 | 12866篇 |
2005年 | 10259篇 |
2004年 | 7261篇 |
2003年 | 6242篇 |
2002年 | 6110篇 |
2001年 | 5414篇 |
2000年 | 4317篇 |
1999年 | 3631篇 |
1998年 | 2364篇 |
1997年 | 1911篇 |
1996年 | 1791篇 |
1995年 | 1537篇 |
1994年 | 1208篇 |
1993年 | 826篇 |
1992年 | 663篇 |
1991年 | 476篇 |
1990年 | 383篇 |
1989年 | 297篇 |
1988年 | 247篇 |
1987年 | 144篇 |
1986年 | 142篇 |
1985年 | 66篇 |
1984年 | 61篇 |
1983年 | 40篇 |
1982年 | 44篇 |
1981年 | 48篇 |
1980年 | 47篇 |
1979年 | 35篇 |
1977年 | 16篇 |
1976年 | 13篇 |
1975年 | 13篇 |
1951年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
Sumeng Wei Yuling Yang Xiao Feng Shanshan Li Lei Zhou Jingyu Wang Xiaozhi Tang 《International Journal of Food Science & Technology》2020,55(7):2691-2699
Structures and properties of myofibrillar protein gel prepared at different power (300–800 W) were evaluated. Amino acid analysis demonstrated that changes in microwave power did not alter primary structure of gel. However, an increase in microwave power could change higher structures of gel. As microwave power increased, α-helix content decreased and β-sheet content increased. Increased microwave power probably facilitated protein to unfold and expose the internal groups, causing surface hydrophobicity and the formation of disulphide bonds were enhanced, which indicated changes in tertiary and quaternary structures of protein. At 500 W, gel had the best ultrastructure where surface morphology, springiness and water holding capacity reached the optimum. Our findings suggested that microwave at an appropriate power (500 W) could change higher structures of myofibrillar protein gel to achieve desired processing and quality protein gel characteristics. 相似文献
43.
44.
Multibody System Dynamics - A recently developed index reduction method is applied to comparatively complicated underactuated mechanical systems in the context of inverse dynamics. The inverse... 相似文献
45.
Jianhuai Dong Zhixuan Dong 《International Journal of Adaptive Control and Signal Processing》2020,34(10):1466-1482
This article studies the optimal filtering and control for wireless networked control systems (WNCSs). In WNCSs, packets may be lost in both control and feedback channels and user datagram protocol is usually used to improve the performance of the real-time control. Relevant literature indicates that the conventional optimal filtering for such a system cannot be applied in practice due to the complex calculation with Gaussian mixtures. This paper proposes a novel scheme to realize the optimal filtering and the linear quadratic Gaussian control for WNCSs, in which the controlled node performs a local estimation and the remote-control node performs the final estimation and control, and a synchronization of two estimators is guaranteed by a communication mechanism. An optimal filtering algorithm is developed, the stability condition of the filtering error covariance is obtained, optimal finite-horizon and infinite-horizon control are derived, and the stability of the closed-loop control system is proved. Numerical simulations show the validity and feasibility of the theoretical results. 相似文献
46.
This paper considers a novel distributed iterative learning consensus control algorithm based on neural networks for the control of heterogeneous nonlinear multiagent systems. The system's unknown nonlinear function is approximated by suitable neural networks; the approximation error is countered by a robust term in the control. Two types of control algorithms, both of which utilize distributed learning laws, are provided to achieve consensus. In the provided control algorithms, the desired reference is considered to be an unknown factor and then estimated using the associated learning laws. The consensus convergence is proven by the composite energy function method. A numerical simulation is ultimately presented to demonstrate the efficacy of the proposed control schemes. 相似文献
47.
48.
Tuntun Wang Dr. Sitansu Sekhar Nanda Dr. Georgia C. Papaefthymiou Prof. Dong Kee Yi 《Chembiochem : a European journal of chemical biology》2020,21(9):1254-1264
The extracellular matrix (ECM) is a macromolecular network that can provide biochemical and structural support for cell adhesion and formation. It regulates cell behavior by influencing biochemical and physical cues. It is a dynamic structure whose components are modified, degraded, or deposited during connective tissue development, giving tissues strength and structural integrity. The physical properties of the natural ECM environment control the design of naturally or synthetically derived biomaterials to guide cell function in tissue engineering. Tissue engineering is an important field that explores physical cues of the ECM to produce new viable tissue for medical applications, such as in organ transplant and organ recovery. Understanding how the ECM exerts physical effects on cell behavior, when cells are seeded in synthetic ECM scaffolds, is of utmost importance. Herein we review recent findings in this area that report on cell behaviors in a variety of ECMs with different physical properties, i.e., topology, geometry, dimensionality, stiffness, and tension. 相似文献
49.
为降低烟草中噁霉灵检测中的基质干扰,提高检测灵敏度和和稳定性,通过试验建立了以QuEChERS为样品前处理方法、液相色谱串联质谱仪为检测仪器的烟草中噁霉灵残留检测方法。样品加水浸润后,经丙酮提取、盐析试剂包除水、石墨化炭黑除杂后,采用Agilent ZORBAX 300SB-C8液相色谱柱(2.1 mm×100 mm,1.8 μm)分离,甲醇-水程序洗脱,ESI雾化,串联质谱MRM检测。结果发现,该方法在0.0025~0.0500 mg/L范围内线性良好,决定系数r2=0.9996,定量检测限1.06 μg/L,回收率在90.8%~92.0%之间,相对标准偏差为5.1%。运用该方法测定烟草中的噁霉灵,操作简单,检测精度高,满足CORESTA对烟草农残检测的要求。 相似文献