全文获取类型
收费全文 | 2686篇 |
免费 | 93篇 |
国内免费 | 152篇 |
专业分类
电工技术 | 27篇 |
综合类 | 48篇 |
化学工业 | 678篇 |
金属工艺 | 235篇 |
机械仪表 | 119篇 |
建筑科学 | 34篇 |
矿业工程 | 8篇 |
能源动力 | 129篇 |
轻工业 | 66篇 |
水利工程 | 7篇 |
石油天然气 | 17篇 |
武器工业 | 7篇 |
无线电 | 260篇 |
一般工业技术 | 601篇 |
冶金工业 | 112篇 |
原子能技术 | 67篇 |
自动化技术 | 516篇 |
出版年
2024年 | 1篇 |
2023年 | 32篇 |
2022年 | 34篇 |
2021年 | 55篇 |
2020年 | 65篇 |
2019年 | 56篇 |
2018年 | 69篇 |
2017年 | 70篇 |
2016年 | 96篇 |
2015年 | 88篇 |
2014年 | 150篇 |
2013年 | 168篇 |
2012年 | 165篇 |
2011年 | 234篇 |
2010年 | 148篇 |
2009年 | 154篇 |
2008年 | 154篇 |
2007年 | 165篇 |
2006年 | 148篇 |
2005年 | 97篇 |
2004年 | 108篇 |
2003年 | 90篇 |
2002年 | 86篇 |
2001年 | 48篇 |
2000年 | 57篇 |
1999年 | 57篇 |
1998年 | 67篇 |
1997年 | 52篇 |
1996年 | 34篇 |
1995年 | 37篇 |
1994年 | 26篇 |
1993年 | 20篇 |
1992年 | 23篇 |
1991年 | 16篇 |
1990年 | 21篇 |
1989年 | 8篇 |
1988年 | 11篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有2931条查询结果,搜索用时 15 毫秒
81.
82.
83.
塑胶原料生产是一个典型的批次生产过程,其MES系统的功能需求不同于离散工业和流程工业,有其行业的特殊性。本文借助英维思MES软件平台,通过对订单的跟踪管理和配方逻辑模型的再造,成功地实现了塑胶原料生产企业ERP(企业资源管理)与PCS(生产控制系统)的信息集成,为流程行业MES系统的实践提供了新的补充,取得了很好的效果。 相似文献
84.
85.
范志强 《计算机工程与应用》2012,48(25):28-33
受4M1E(人、机、料、法、环)因素的随机波动影响,产品的制造过程通常是不完美的,从而产生不良产品.针对已有研究多忽略不良产品的特点,建立了更加符合实际需求的订单分配多目标混合整数规划模型,其优化目标为最小化交易成本、采购成本、不良产品数量、产品延迟交付数量,以及最大化供应商信誉评价.考虑到模型求解的复杂度,设计了一种模拟退火算法,并结合启发式规则避免了大量非法初始解与邻点解的出现.实验算例表明所建立的模型能够反映订单分配过程中的产品缺陷现象,其算法能够在允许的运算时间内获得稳定的满意解,并且随着算例规模的增大,其计算时间与优化结果均优于LINGO软件. 相似文献
86.
The amorphous hydrous manganese oxide (denoted as a-MnOx·nH2O) was anodically deposited from the MnSO4 solutions of various pH values. The capacitive characteristics and stability of this oxide without and with annealing in air for 2 h up to 400 °C were systematically investigated in aqueous electrolytes through means of cyclic voltammetry (CV) and the constant-current charge-discharge method. The redox properties of a-MnOx·nH2O were strongly affected by the electrolytes employed and this oxide exhibited ideally capacitive behavior in 0.1 M Na2SO4 and 0.3 M KCl. The stability of this amorphous hydrous oxide was enhanced by the annealing treatment while its capacitance was gradually decreased with increasing the annealing temperature. The amorphous structure and surface morphologies of a-MnOx·nH2O with annealing at different temperatures were, respectively, examined in terms of the X-ray diffraction (XRD) patterns and scanning electron microscopic (SEM) photographs. The oxidation states of these a-MnOx·nH2O deposits were studied by X-ray photoelectron spectroscopy (XPS). 相似文献
87.
针对非刚体形状控制点匹配中存在的对应性和有偏性问题,提出一个基于混合t聚类的鲁棒点匹配模型。该模型结合了混合t分布聚类和薄片样条匹配各自的优点,混合t聚类充分利用t分布的小样本和较大尾迹优势取得局部聚类的鲁棒性,并可方便地引入新的成员分布概率建模局外点,解决全局的鲁棒性;薄片样条能完全分解非刚体映射的仿射和非仿射变换。实验证明,利用确定性退火和EM(期望最大化)迭代技术,对模型中的鲁棒聚类和非刚体点匹配进行联合优化,可以有效解决非刚体点匹配的对应性和有偏性问题;通过在退火过程中应用一个模型选择准则,可以进一步提高匹配的精度,对比结果证实了该模型的鲁棒性。 相似文献
88.
X-ray diffraction (XRD), current–voltage (IV), capacitance–voltage (CV), deep-level transient Fourier spectroscopy (DLTFS) and isothermal transient spectroscopy (ITS) techniques are used to investigate the thermal annealing behaviour of three deep levels in Ga0.986In0.014As heavily doped with Si (6.8 × 1017 cm−3) grown by molecular beam epitaxy (MBE). The thermal annealing was performed at 625 °C, 650 °C, 675 °C, 700 °C and 750 °C for 5 min. XRD study shows good structural quality of the samples and yields an In composition of 1.4%. Two main electron traps are detected by DLTFS and ITS around 280 K, with activation energies of 0.58 eV and 0.57 eV, capture cross sections of 9 × 10−15 cm2 and 8.6 × 10−14 cm2 and densities of 2.8 × 1016 cm−3 and 9.6 × 1015 cm−3, respectively. They appear overlapped and as a single peak, which divides into two smaller peaks after annealing at 625 °C for 5 min.
Annealing at higher temperatures further reduces the trap concentrations. A secondary electron trap is found at 150 K with an activation energy of 0.274 eV, a capture cross section of 8.64 × 10−15 cm2 and a density of 1.38 × 1015 cm−3. The concentration of this trap level is also decreased by thermal annealing. 相似文献
89.
80 nm-thick Ni50Fe50 layers were sputter-deposited on glass substrates at 400 °C and then Au layers were sputter-deposited on the Ni50Fe50 layers. The Au/Ni50Fe50 bilayer films were annealed in a vacuum of 5×10−4 Pa from 250 to 450 °C for 30 min or 90 min. The characteristics of the Au layers were studied by Auger electron spectroscopy, field emission scanning electron microscopy, X-ray diffraction and a four-point probe technique. When the annealing temperature reaches 450 °C, Fe and Ni atoms diffuse markedly into the Au layer and the Fe content is more than the Ni content. When the annealing temperature is lower than 450 °C, the grain size of the Au layers does not change markedly with annealing temperature. However, as the annealing temperature reaches 450 °C, the annealing promotes the grain growth of the Au layer. As the annealing temperature exceeds 300 °C, the resistivity of the bilayer films increases with increasing annealing temperature. The diffusion of Fe and Ni atoms into the Au layer results in an increase in the resistivity of the annealed bilayer film. Large numbers of Fe and Ni atoms diffusing into the Au layer of the annealed Au/Ni50Fe50 bilayer film lead to a significant decrease in the lattice constant of the Au layer. 相似文献
90.
Li Chun-fu Zhang Jie Wang Gui-zeng 《Frontiers of Electrical and Electronic Engineering in China》2006,1(2):211-215
There are usually no on-line product quality measurements in batch and semi-batch processes, which make the process control
task very difficult. In this paper, a model for predicting the end-product quality from the available on-line process variables
at the early stage of a batch is developed using partial least squares (PLS) method. Furthermore, some available mid-course
quality measurements are used to rectify the final prediction results. To deal with the problem that the process may change
with time, recursive PLS (RPLS) algorithm is used to update the model based on the new batch data and the old model parameters
after each batch. An application to a simulated batch MMA polymerization process demonstrates the effectiveness of the proposed
method.
__________
Translated from Jorunal of Tsinghua Science and Technology(Natural Science Edition), 2004, 44(10): 1360–1363 (in Chinese) 相似文献