全文获取类型
收费全文 | 332884篇 |
免费 | 4135篇 |
国内免费 | 1266篇 |
专业分类
电工技术 | 5565篇 |
综合类 | 2504篇 |
化学工业 | 47041篇 |
金属工艺 | 14067篇 |
机械仪表 | 10502篇 |
建筑科学 | 8178篇 |
矿业工程 | 1431篇 |
能源动力 | 8309篇 |
轻工业 | 24562篇 |
水利工程 | 3411篇 |
石油天然气 | 3565篇 |
武器工业 | 15篇 |
无线电 | 43204篇 |
一般工业技术 | 65158篇 |
冶金工业 | 50975篇 |
原子能技术 | 5328篇 |
自动化技术 | 44470篇 |
出版年
2021年 | 2177篇 |
2020年 | 1563篇 |
2019年 | 1920篇 |
2018年 | 17228篇 |
2017年 | 16164篇 |
2016年 | 13027篇 |
2015年 | 2789篇 |
2014年 | 4171篇 |
2013年 | 11652篇 |
2012年 | 9217篇 |
2011年 | 17587篇 |
2010年 | 14823篇 |
2009年 | 13218篇 |
2008年 | 14887篇 |
2007年 | 15772篇 |
2006年 | 7477篇 |
2005年 | 7638篇 |
2004年 | 7338篇 |
2003年 | 7649篇 |
2002年 | 6551篇 |
2001年 | 6607篇 |
2000年 | 6139篇 |
1999年 | 6448篇 |
1998年 | 16546篇 |
1997年 | 11446篇 |
1996年 | 8843篇 |
1995年 | 6624篇 |
1994年 | 5920篇 |
1993年 | 5860篇 |
1992年 | 4148篇 |
1991年 | 4047篇 |
1990年 | 3858篇 |
1989年 | 3651篇 |
1988年 | 3571篇 |
1987年 | 3017篇 |
1986年 | 2943篇 |
1985年 | 3211篇 |
1984年 | 2931篇 |
1983年 | 2831篇 |
1982年 | 2639篇 |
1981年 | 2552篇 |
1980年 | 2462篇 |
1979年 | 2306篇 |
1978年 | 2112篇 |
1977年 | 2613篇 |
1976年 | 3566篇 |
1975年 | 1766篇 |
1974年 | 1729篇 |
1973年 | 1665篇 |
1972年 | 1466篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
92.
93.
94.
Detailed study on fusion characteristics of rigid poly(vinyl chloride) nanocomposites: The comparison of using multiple regression analysis and artificial neural network
下载免费PDF全文
![点击此处可从《乙烯基与添加剂工艺杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Fusion behavior of poly(vinyl chloride) (PVC) compounds plays an important role in the development of physical properties of processed material. The fusion characteristics in PVC processing are governed by material variables that affect the fusion with some interactions. In this research, the aim was to characterize the effects of formulation ingredients on fusion characteristics of PVC. Four material parameters, including the contents of nanoclay (NC), azodicarbonamide, calcium stearate, and processing aid, are proposed as affecting variables. The fusion time (FT) as well as fusion factor (FF) are considered fusion indicators and are experimentally determined in some different levels of affecting parameters. The multivariable regression analysis (MRA) and the Artificial Neural Network (ANN) modeling are considered as two analytical methods. The regression analysis result for the FT denotes, in part, significant linear and quadratic effects of NC and also its significant interactions with azodicarbonamide and calcium stearate, whereas that of FF indicates only a linear effect of NC. ANN modeling is performed with a three‐layer (input, hidden, and output) neural network. The results of the comparison of the MRA and ANN predictions with experimental values are reported as the correlation coefficient (R2), mean‐square error, and mean absolute percentage error for both FF and FT parameters. The obtained values clearly denote that the ANN results are more precise and especially more general than those of MRA. However, in the case of FT, improvement of the ANN modeling is much greater than that of FF. J. VINYL ADDIT. TECHNOL., 21:147–155, 2015. © 2014 Society of Plastics Engineers 相似文献
95.
Variations of Incomplete Open Cubes is the major project by the twentieth-century conceptual artist Sol LeWitt. In this paper we interpret the enumerative component of the project as embeddings of graphs. This formulation permits use of an algorithm to check the completeness of the list of the structures produced by the artist. Our conclusion is that the artist found the correct number of structures (that is, 122), but that his list contains a mistake in the presentation of a pair of incomplete cubes, a discovery that appears not to have been noted before. 相似文献
96.
Neural Computing and Applications - With an increase in online longitudinal users’ interactions, capturing users’ precise preferences and giving accurate recommendations have become an... 相似文献
97.
98.
Jonathan K. Dozier Mark D. Distefano 《International journal of molecular sciences》2015,16(10):25831-25864
The use of proteins as therapeutics has a long history and is becoming ever more common in modern medicine. While the number of protein-based drugs is growing every year, significant problems still remain with their use. Among these problems are rapid degradation and excretion from patients, thus requiring frequent dosing, which in turn increases the chances for an immunological response as well as increasing the cost of therapy. One of the main strategies to alleviate these problems is to link a polyethylene glycol (PEG) group to the protein of interest. This process, called PEGylation, has grown dramatically in recent years resulting in several approved drugs. Installing a single PEG chain at a defined site in a protein is challenging. Recently, there is has been considerable research into various methods for the site-specific PEGylation of proteins. This review seeks to summarize that work and provide background and context for how site-specific PEGylation is performed. After introducing the topic of site-specific PEGylation, recent developments using chemical methods are described. That is followed by a more extensive discussion of bioorthogonal reactions and enzymatic labeling. 相似文献
99.
100.