全文获取类型
收费全文 | 110528篇 |
免费 | 10709篇 |
国内免费 | 6538篇 |
学科分类
工业技术 | 127775篇 |
出版年
2024年 | 353篇 |
2023年 | 1611篇 |
2022年 | 2918篇 |
2021年 | 4214篇 |
2020年 | 3246篇 |
2019年 | 2579篇 |
2018年 | 2957篇 |
2017年 | 3339篇 |
2016年 | 3063篇 |
2015年 | 4333篇 |
2014年 | 5675篇 |
2013年 | 6581篇 |
2012年 | 7512篇 |
2011年 | 8000篇 |
2010年 | 7461篇 |
2009年 | 7186篇 |
2008年 | 7319篇 |
2007年 | 6810篇 |
2006年 | 6710篇 |
2005年 | 5518篇 |
2004年 | 4242篇 |
2003年 | 3946篇 |
2002年 | 4623篇 |
2001年 | 3901篇 |
2000年 | 2696篇 |
1999年 | 2266篇 |
1998年 | 1563篇 |
1997年 | 1334篇 |
1996年 | 1250篇 |
1995年 | 983篇 |
1994年 | 840篇 |
1993年 | 568篇 |
1992年 | 486篇 |
1991年 | 377篇 |
1990年 | 273篇 |
1989年 | 239篇 |
1988年 | 175篇 |
1987年 | 141篇 |
1986年 | 105篇 |
1985年 | 62篇 |
1984年 | 66篇 |
1983年 | 28篇 |
1982年 | 47篇 |
1981年 | 40篇 |
1980年 | 27篇 |
1979年 | 24篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1959年 | 17篇 |
1951年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
63.
64.
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
65.
Hao Li Pengcheng Zhang Shengquan Yu Hongyu Yang Bin Tang Fuhai Li Shuren Zhang 《Ceramics International》2019,45(9):11639-11647
Mg2(Ti1-xSnx)O4 (x?=?0–1) ceramics were prepared through conventional solid-state method. This paper focused on the dependence of microwave dielectric properties on crystal structural characteristics via crystal structure refinement, Raman spectra study and complex chemical bond theory. XRD spectrums delineated the phase information of a spinel structure, and structural characteristic of these compositions were achieved with the help of Rietveld refinements. Raman spectrums were used to depict the correlations between vibrational phonon modes and dielectric properties. The variation of permittivity is ascribed to the Mg2(Ti1-xSnx)O4 average bond covalency. The relationship among the B-site octahedral bond energy, tetrahedral bond energy and temperature coefficient are discussed by defining on the change rate of bond energy and the contribution rate of octahedral bond energy. The quality factor is affected by systematic total lattice energy, and the research of XPS patterns illustrated that oxygen vacancies can be effectively restrained in rich oxygen sintering process. Obviously, the microwave dielectric properties of Mg2(Ti1-xSnx)O4 compounds were obtained (= 12.18, ?=?170,130?GHz, ?=??53.1?ppm/°C, x?=?0.2). 相似文献
66.
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
67.
Yao Dajie Liu Xiaofei Wu Jian 《International Journal of Control, Automation and Systems》2020,18(9):2251-2258
International Journal of Control, Automation and Systems - In this paper, the tracking problem for a class of uncertain nonlinearly parameterized systems with input delay based the adaptive... 相似文献
68.
针对电牵引采煤机渐开线行走轮在ANSYS分析中存在的问题,提出运用APDL语言命令直接建模,并通过VB与ANSYS的交互运行途径,设计了基于VB界面和程序的软件,实现了利用VB界面直接输入参数并调用ANSYS对行走轮自动建模、加载和计算的有限元分析。验证结果表明,该软件减少了设计人员的重复劳动,提高了行走轮的设计效率和水平,具有一定的工程实用价值。 相似文献
69.
70.