全文获取类型
收费全文 | 3066篇 |
免费 | 32篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 32篇 |
化学工业 | 181篇 |
金属工艺 | 43篇 |
机械仪表 | 31篇 |
建筑科学 | 5篇 |
能源动力 | 38篇 |
轻工业 | 50篇 |
水利工程 | 2篇 |
石油天然气 | 3篇 |
无线电 | 101篇 |
一般工业技术 | 237篇 |
冶金工业 | 2280篇 |
原子能技术 | 8篇 |
自动化技术 | 89篇 |
出版年
2023年 | 9篇 |
2022年 | 15篇 |
2021年 | 17篇 |
2020年 | 17篇 |
2019年 | 21篇 |
2018年 | 29篇 |
2017年 | 33篇 |
2016年 | 45篇 |
2015年 | 12篇 |
2014年 | 32篇 |
2013年 | 86篇 |
2012年 | 34篇 |
2011年 | 60篇 |
2010年 | 47篇 |
2009年 | 41篇 |
2008年 | 35篇 |
2007年 | 36篇 |
2006年 | 41篇 |
2005年 | 33篇 |
2004年 | 21篇 |
2003年 | 22篇 |
2002年 | 22篇 |
2001年 | 15篇 |
2000年 | 14篇 |
1999年 | 82篇 |
1998年 | 648篇 |
1997年 | 373篇 |
1996年 | 285篇 |
1995年 | 166篇 |
1994年 | 134篇 |
1993年 | 135篇 |
1992年 | 37篇 |
1991年 | 43篇 |
1990年 | 35篇 |
1989年 | 44篇 |
1988年 | 53篇 |
1987年 | 48篇 |
1986年 | 28篇 |
1985年 | 40篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 14篇 |
1981年 | 16篇 |
1980年 | 19篇 |
1978年 | 6篇 |
1977年 | 41篇 |
1976年 | 89篇 |
1975年 | 3篇 |
1973年 | 4篇 |
1972年 | 2篇 |
排序方式: 共有3100条查询结果,搜索用时 15 毫秒
1.
Chattopadhyay Arup Kumar Nag Amitava Singh Jyoti Prakash 《Multimedia Tools and Applications》2022,81(24):34969-34999
Multimedia Tools and Applications - A secret sharing scheme partitions a secret into a set of shares and distributes them among the eligible participants, with each participant receiving one share... 相似文献
2.
S. Sarkar P. Mohan Raj S. Chakraborty G. Phanikumar K. Chattopadhyay P. Dutta 《Journal of Materials Science》2003,38(1):155-164
A three dimensional, transient model is developed for studying heat transfer, fluid flow and mass transfer for the case of a single-pass laser surface alloying process. The numerical study is performed in a co-ordinate system fixed to the laser which moves with a constant scanning speed. The coupled momentum, energy and species conservation equations are solved using a finite volume technique. Phase change processes are modelled using a fixed-grid enthalpy-porosity technique, which is capable of predicting the continuously evolving solid-liquid interface. The three-dimensional model is able to predict the species concentration distribution inside the molten pool during alloying, as well as in the entire cross section of the solidified alloy. Corresponding experimental results show a good qualitative agreement with the numerical predictions with regard to pool shape and final composition distribution. 相似文献
3.
4.
PE Sipila VJ Wiebe GB Hubbard SK Koester VD Emshoff JU Maenpaa GT Wurz RC Seymour MW DeGregorio 《Canadian Metallurgical Quarterly》1993,(15):2138-2144
The effects of long-term tamoxifen exposure on cell growth and cell cycle kinetics were compared between oestrogen receptor (ER)-positive (MCF-7) and ER-negative (MDA-MB-231) cell lines. In the MCF-7 cell line, prolonged tamoxifen exposure (0.5 mumol/l for > 100 days) blocked cells in G0-G1 of the cell cycle, and slowed the doubling time of cells from 30 to 59 h. These effects corresponded to an increase in the cellular accumulation of tamoxifen over time [mean area under concentration curve (AUC) = 77.92 mumoles/10(6)/cells/day]. In contrast, in the MDA-MB-231 cell line, long-term tamoxifen exposure had no obvious effect on the doubling time, and reduced cellular tamoxifen accumulation (mean AUC = 50.50 mumoles/10(6)/cells/day) compared to the MCF-7 cells. Flow cytometric analysis of MDA-MB-231 cells demonstrated that a new tetraploid clone emerged following 56 days of tamoxifen exposure. Inoculation of the MDA-MB-231 tetraploid clone and MDA-MB-231 wildtype cells into the opposite flanks of athymic nude mice resulted in the rapid growth of tetraploid tumours. The tetraploid tumours maintained their ploidy following tamoxifen treatment for nine consecutive serial transplantations. Histological examination of the fifth transplant generation xenografts revealed that the tetraploid tumour had a 25-30 times greater mass, area of haemorrhage and necrosis, a slightly higher mitotic index and was more anaplastic than the control neoplasm. The control wildtype MDA-MB-231 tumours maintained a stable ploidy following tamoxifen treatment until the eighth and ninth transplantation, when a tetraploid population appeared, suggesting that tamoxifen treatment may select for this clone in vivo. These studies suggest that prolonged tamoxifen exposure may select for new, stable, fast growing cell clones in vitro as well as in vivo. 相似文献
5.
6.
7.
The present study concerns the effect of copper additions on the microstructural evolution and mechanical properties of directly
quenched Ti–B steels. Ti and B are added as microalloying elements with an aim of achieving adequate austenite hardenability
and Cu is added to retard the austenite (γ) → ferrite (α) transformation. Therefore, the microalloying and Cu additions together allow the transformation of austenite to occur at
a lower temperature, resulting in a finer microstructure containing martensitic constituents. The direct-quenching route is
adopted with an aim of facilitating the nucleation of the constituent phases from the deformed austenite. In order to circumvent
the hot-shortness due to the Cu addition, 0.79 wt% Ni has been added to one of the 1.5 wt% Cu microalloyed steels. The present
study has demonstrated that the Ni-containing 1.5Cu–Ti–B steel is capable of providing an attractive combination of strength
and ductility comparable to the high strength varieties of HSLA steels in directly quenched condition. 相似文献
8.
9.
10.