全文获取类型
收费全文 | 3099篇 |
免费 | 211篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 89篇 |
综合类 | 4篇 |
化学工业 | 725篇 |
金属工艺 | 65篇 |
机械仪表 | 99篇 |
建筑科学 | 101篇 |
矿业工程 | 8篇 |
能源动力 | 119篇 |
轻工业 | 496篇 |
水利工程 | 14篇 |
石油天然气 | 16篇 |
无线电 | 190篇 |
一般工业技术 | 775篇 |
冶金工业 | 146篇 |
原子能技术 | 14篇 |
自动化技术 | 450篇 |
出版年
2023年 | 22篇 |
2021年 | 59篇 |
2020年 | 55篇 |
2019年 | 66篇 |
2018年 | 116篇 |
2017年 | 109篇 |
2016年 | 142篇 |
2015年 | 105篇 |
2014年 | 145篇 |
2013年 | 334篇 |
2012年 | 213篇 |
2011年 | 223篇 |
2010年 | 182篇 |
2009年 | 134篇 |
2008年 | 143篇 |
2007年 | 119篇 |
2006年 | 96篇 |
2005年 | 52篇 |
2004年 | 34篇 |
2003年 | 49篇 |
2002年 | 38篇 |
2001年 | 31篇 |
2000年 | 39篇 |
1999年 | 33篇 |
1998年 | 60篇 |
1997年 | 29篇 |
1996年 | 52篇 |
1995年 | 28篇 |
1994年 | 39篇 |
1993年 | 35篇 |
1992年 | 24篇 |
1991年 | 23篇 |
1990年 | 23篇 |
1989年 | 18篇 |
1988年 | 13篇 |
1985年 | 32篇 |
1984年 | 34篇 |
1983年 | 29篇 |
1982年 | 25篇 |
1981年 | 40篇 |
1980年 | 38篇 |
1979年 | 26篇 |
1978年 | 25篇 |
1977年 | 21篇 |
1976年 | 26篇 |
1975年 | 13篇 |
1974年 | 11篇 |
1973年 | 15篇 |
1972年 | 14篇 |
1968年 | 11篇 |
排序方式: 共有3311条查询结果,搜索用时 31 毫秒
131.
132.
Spray drying is a very useful method for manufacturing of amorphous solid materials. This is mainly due to the possibility of fast solvent evaporation that leads to a rapid transformation of solution to a solid state. Besides evaporation kinetics, there are various process parameters that influence physical and chemical characteristics of such obtained material. The possibility of obtaining a stable amorphous structure of the active pharmaceutical ingredient in a spray dryer was examined. A solution of the hydrochloride crystalline structure of the active pharmaceutical ingredient in a mixture of water and acetonitrile was dried at different temperatures and flowrates of nitrogen used for atomization, as well as the flowrates of the solution. The influence of the process conditions on the properties of the product was analyzed. The final dried products were characterized and identified with a variety of analytical and physical methods. The results showed that a stable amorphous structure of the high purity active pharmaceutical ingredient is obtained, and that the optimal conditions of the process are defined. The amorphous structure is stable at temperatures below 200°C when it is transformed into a new crystal structure. Conditions of high relative air humidity lead to partial transformation. 相似文献
133.
Miloje S. Radenković 《International journal of control》2019,92(2):404-415
Existing adaptive control algorithms at best guarantee that the tracking error is a l 2 sequence. This paper presents globally stable adaptive control algorithms for linear discrete-time systems providing l 1 tracking performance. Two algorithms with different degree of complexity are proposed, one for the case of known control directions, and a separate algorithm for the case of unknown control directions. It is demonstrated that in both cases the tracking error is l 1 sequence, while the input and output signals are uniformly bounded. 相似文献
134.
135.
136.
Neural Computing and Applications - In the paper, the authors elaborate a recent research concerning the originality of artworks in terms of self-organization in the complex systems physics. It has... 相似文献
137.
138.
139.
140.
In modern wireless ad hoc networks, with a high speed PHY, every collision means a significant loss of useful bandwidth. In the last few years different binary contention protocols have been introduced to address this problem. In this work we propose a novel binary contention protocol called binary priority countdown (BPC) protocol, whose goal is to reduce collisions as well as contention time. BPC uses a new priority countdown mechanism which exploits the efficiency of binary countdown, but the priority countdown process is not constrained to a single binary countdown round. This way, the priority space is not defined by the length of binary countdown round, like in other binary countdown protocols proposed in the literature, and arbitrary medium access priorities can be decremented through multiple binary countdown rounds if necessary. The ability of a new priority countdown mechanism to count down any priority number without changing the length of a binary countdown round, allows independent management of priority space. This “independence” of priority space introduces new optimization and adaptation possibilities. Collision memory effect is recognized and described. BPC protocol reveals connection between unary, binary and digit contention protocols. All three groups of protocols can now be seen as members of the same class of contention algorithms. Preliminary simulation results are shown. 相似文献