全文获取类型
收费全文 | 4592篇 |
免费 | 211篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 56篇 |
化学工业 | 1426篇 |
金属工艺 | 143篇 |
机械仪表 | 73篇 |
建筑科学 | 103篇 |
矿业工程 | 13篇 |
能源动力 | 136篇 |
轻工业 | 578篇 |
水利工程 | 13篇 |
石油天然气 | 10篇 |
无线电 | 88篇 |
一般工业技术 | 689篇 |
冶金工业 | 1070篇 |
原子能技术 | 26篇 |
自动化技术 | 382篇 |
出版年
2023年 | 38篇 |
2022年 | 193篇 |
2021年 | 313篇 |
2020年 | 103篇 |
2019年 | 89篇 |
2018年 | 158篇 |
2017年 | 163篇 |
2016年 | 165篇 |
2015年 | 131篇 |
2014年 | 168篇 |
2013年 | 268篇 |
2012年 | 189篇 |
2011年 | 242篇 |
2010年 | 156篇 |
2009年 | 138篇 |
2008年 | 136篇 |
2007年 | 142篇 |
2006年 | 93篇 |
2005年 | 68篇 |
2004年 | 70篇 |
2003年 | 56篇 |
2002年 | 49篇 |
2001年 | 30篇 |
2000年 | 34篇 |
1999年 | 32篇 |
1998年 | 188篇 |
1997年 | 208篇 |
1996年 | 140篇 |
1995年 | 99篇 |
1994年 | 47篇 |
1993年 | 68篇 |
1992年 | 24篇 |
1991年 | 14篇 |
1990年 | 18篇 |
1989年 | 18篇 |
1988年 | 17篇 |
1987年 | 16篇 |
1986年 | 15篇 |
1985年 | 22篇 |
1984年 | 33篇 |
1983年 | 23篇 |
1982年 | 42篇 |
1981年 | 48篇 |
1980年 | 56篇 |
1979年 | 29篇 |
1978年 | 37篇 |
1977年 | 109篇 |
1976年 | 239篇 |
1975年 | 14篇 |
1973年 | 12篇 |
排序方式: 共有4806条查询结果,搜索用时 0 毫秒
71.
We present an overview of some recent developments in the area of mathematical modeling of maintenance decisions for multi-unit systems. The emphasis is on three main groups of multicomponent maintenance optimization models: the block replacement models, group maintenance models, and opportunistic maintenance models. Moreover, an example of a two-unit system maintenance process is provided in order to compare various maintenance policies. 相似文献
72.
Robust ordinal regression in preference learning and ranking 总被引:1,自引:0,他引:1
Salvatore Corrente Salvatore Greco Miłosz Kadziński Roman Słowiński 《Machine Learning》2013,93(2-3):381-422
Multiple Criteria Decision Aiding (MCDA) offers a diversity of approaches designed for providing the decision maker (DM) with a recommendation concerning a set of alternatives (items, actions) evaluated from multiple points of view, called criteria. This paper aims at drawing attention of the Machine Learning (ML) community upon recent advances in a representative MCDA methodology, called Robust Ordinal Regression (ROR). ROR learns by examples in order to rank a set of alternatives, thus considering a similar problem as Preference Learning (ML-PL) does. However, ROR implements the interactive preference construction paradigm, which should be perceived as a mutual learning of the model and the DM. The paper clarifies the specific interpretation of the concept of preference learning adopted in ROR and MCDA, comparing it to the usual concept of preference learning considered within ML. This comparison concerns a structure of the considered problem, types of admitted preference information, a character of the employed preference models, ways of exploiting them, and techniques to arrive at a final ranking. 相似文献
73.
Mikołaj Bojańczyk 《Theory of Computing Systems》2013,53(2):194-222
We develop an algebraic theory for languages of data words. We prove that, under certain conditions, a language of data words is definable in first-order logic if and only if its syntactic monoid is aperiodic. 相似文献
74.
Concentration dependant emission spectra and fluorescence dynamic profiles have been investigated in PrxLa1−xAlO3 single crystals in order to better understand processes responsible for concentration quenching of the praseodymium 3P0 and 1D2 emissions. The cross-relaxation transfer rates were experimentally determined as a function of Pr3+ concentration. Decays were modeled and nearest-neighbor trapping rates were calculated. 相似文献
75.
L. Demkowicz P. Gatto J. Kurtz M. Paszyński W. Rachowicz E. Bleszyński M. Bleszyński M. Hamilton C. Champlin D. Pardo 《Computer Methods in Applied Mechanics and Engineering》2011,200(21-22):1757-1773
We focus on the development of a reliable numerical model for investigating the bone-conduction of sound in the human head. The main challenge of the problem is the lack of fundamental knowledge regarding the transmission of acoustic energy through non-airborne pathways to the cochlea. A fully coupled model based on the acoustic/elastic interaction problem with a detailed resolution of the cochlea region and its interface with the skull and the air pathways, should provide an insight into this fundamental, long standing research problem. To this aim we have developed a 3D hp-finite element code that supports elements of all shapes (tetrahedra, prisms and pyramids) to better capture the geometrical features of the head. We have tested the code on a multilayered sphere and employed it to solve an idealized model of head. In the future we hope to attack a model with a more realistic geometry. 相似文献
76.
In this paper the minmax (regret) versions of some basic polynomially solvable deterministic network problems are discussed. It is shown that if the number of scenarios is unbounded, then the problems under consideration are not approximable within log1−?K for any ?>0 unless NP⊆DTIME(npolylogn), where K is the number of scenarios. 相似文献
77.
78.
79.
Orli Thau‐Zuchman 《Lipid Technology》2015,27(3):63-66
Traumatic brain injury (TBI) is becoming increasingly recognised as a major cause of disability, with a significant impact on health costs both in the developed and developing world. At present, there is no effective treatment for this type of acute neurological injury. Docosahexaenoic acid (DHA) is an abundant polyunsaturated fatty acid in the brain, known to have a significant structural role as well as functional roles. Preclinical accumulating evidence indicates that DHA has potential as a restorative therapeutic agent for traumatic brain injury. 相似文献
80.
Jadwiga Bucheska 《应用聚合物科学杂志》1996,60(4):519-529
Nuclear magnetic resonance spectroscopy was used to investigate the position of active centers in polyamide fibers subjected to graft copolymerization with poly(acrylic acid), poly(itaconic acid), and poly(2-vinylpyridine) initiated by thermal oxidation in air. As a result, structural changes in polyamide fibers brought about by oxidation and subsequent grafting of the above mentioned polymers were observed. It was estimated that the generation of active centers that initiate the copolymerization take place at the nitrogen atoms of the amide groups in the polyamide chain. This was confirmed by the broadening of the absorption band for the methylone group adjacent to the nitrogen as well as by the absence of a new absorption band for the methine groups, assuming that the generation of active centers and grafting would take place at the carbon atom of the methylene group in position α to the amide group. © 1996 John Wiley & Sons, Inc. 相似文献