全文获取类型
收费全文 | 6119篇 |
免费 | 394篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 40篇 |
综合类 | 6篇 |
化学工业 | 1224篇 |
金属工艺 | 80篇 |
机械仪表 | 113篇 |
建筑科学 | 225篇 |
矿业工程 | 19篇 |
能源动力 | 175篇 |
轻工业 | 1062篇 |
水利工程 | 60篇 |
石油天然气 | 19篇 |
无线电 | 396篇 |
一般工业技术 | 945篇 |
冶金工业 | 912篇 |
原子能技术 | 38篇 |
自动化技术 | 1202篇 |
出版年
2024年 | 3篇 |
2023年 | 43篇 |
2022年 | 51篇 |
2021年 | 202篇 |
2020年 | 130篇 |
2019年 | 149篇 |
2018年 | 201篇 |
2017年 | 225篇 |
2016年 | 255篇 |
2015年 | 182篇 |
2014年 | 298篇 |
2013年 | 490篇 |
2012年 | 459篇 |
2011年 | 433篇 |
2010年 | 343篇 |
2009年 | 325篇 |
2008年 | 324篇 |
2007年 | 297篇 |
2006年 | 174篇 |
2005年 | 157篇 |
2004年 | 142篇 |
2003年 | 140篇 |
2002年 | 118篇 |
2001年 | 69篇 |
2000年 | 61篇 |
1999年 | 78篇 |
1998年 | 329篇 |
1997年 | 202篇 |
1996年 | 154篇 |
1995年 | 100篇 |
1994年 | 71篇 |
1993年 | 68篇 |
1992年 | 33篇 |
1991年 | 28篇 |
1990年 | 31篇 |
1989年 | 20篇 |
1988年 | 16篇 |
1987年 | 17篇 |
1986年 | 10篇 |
1985年 | 10篇 |
1984年 | 3篇 |
1983年 | 8篇 |
1982年 | 10篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1978年 | 5篇 |
1977年 | 9篇 |
1976年 | 24篇 |
1975年 | 3篇 |
1972年 | 2篇 |
排序方式: 共有6516条查询结果,搜索用时 16 毫秒
71.
72.
JC López Pacios L Parra Muntaner MC Pi?eiro Fernández SC Gómez Cisneros E Sánchez Sánchez JA Rivas Escudero FJ Madrid García J García Alonso 《Canadian Metallurgical Quarterly》1998,51(4):331-333
The occurrence of secondary hypogonadism is a common finding in males who seek help with erectile dysfunction, although the relationship to diminished testosterone is unclear. Two possibilities exist regarding both the genesis and maintenance of the hypogonadotropic hypogonadal state. First, a defect in hypothalamic function, resulting in downregulation as well as in alterations of anterior pituitary function; second, estradiol inhibition of gonadotropin release, both of which result in decreased testosterone production. As testosterone levels decrease and estradiol levels increase, the ratio of free testosterone to estradiol reaches a critical point and the estrogenic gonadotropin suppressive effects predominate. This ratio may signal the biological point of no return and could become one of the criteria for defining the separation of the transitional hypogonadal state from the final 'end stage' hypogonadotropic hypogonadal state. As the aging process continues, there is a relative accumulation of fatty tissue, and aromatization accelerates the conversion of testosterone to estradiol. This additional secondary estradiol inhibition results in the maintenance of the testosterone deficient state, and the aging process continues uncontested. 相似文献
73.
P Neumann JE Berglund E Fernández Mondéjar A Magnusson G Hedenstierna 《Canadian Metallurgical Quarterly》1998,85(4):1533-1543
Oleic acid (OA) injection, lung lavage, and endotoxin infusion are three commonly used methods to induce experimental lung injury. The dynamics of lung collapse and recruitment in these models have not been studied, although knowledge of this is desirable to establish ventilatory techniques that keep the lungs open. We measured lung density by computed tomography during breath-holding procedures. Lung injury was induced with OA, lung lavage, or endotoxin in groups of six mechanically ventilated pigs. After a stabilization period, repetitive computed tomography scans of the same slice were obtained during prolonged expirations with and without positive end-expiratory pressure and during prolonged inspirations after 5 and 30 s of expiration. Lung collapse and recruitment occurred mainly within the first 4 s of breath-holding procedures in all three lung injury models, and some collapse and recruitment occurred even within 0.6 s. OA-injured lungs were significantly more unstable than lungs injured by bronchoalveolar lavage or endotoxin infusion. In this experimental setting, expiration times <0.6 s are required to avoid cyclic alveolar collapse during mechanical ventilation without extrinsic positive end-expiratory pressure. 相似文献
74.
Javier Vioque Julio E. Pastor Eduardo Vioque 《Journal of the American Oil Chemists' Society》1993,70(11):1157-1158
Oil and triglyceride contents and fatty acid composition were determined for seeds in nine taxa belonging to the genusCoincya (Brassicaceae) on the Iberian Peninsula (Spain and Portugal). The oil content ranges from 11.1 to 24.6%, triglycerides from
68.7 to 88.5%. The major fatty acids were erucic (24.6–30.5%), linolenic (17.7–27.7%), linoleic (13.9–24.6%) and oleic acid
(12.3–21.8%). 相似文献
75.
The Journal of Supercomputing - DNA methylation analysis has become an important topic in the study of human health. DNA methylation analysis requires not only a specific treatment of DNA samples... 相似文献
76.
Fernández Álvaro Fernández Camino Miguel-Dávila José-Ángel Conde Miguel Á. 《The Journal of supercomputing》2021,77(3):2302-2325
The Journal of Supercomputing - The integration of a Supercomputer in the educational process improves student’s technological skills. The aim of the paper is to study the interaction between... 相似文献
77.
Palomares Iván Martínez-Cámara Eugenio Montes Rosana García-Moral Pablo Chiachio Manuel Chiachio Juan Alonso Sergio Melero Francisco J. Molina Daniel Fernández Bárbara Moral Cristina Marchena Rosario de Vargas Javier Pérez Herrera Francisco 《Applied Intelligence》2021,51(9):6497-6527
Applied Intelligence - The17 Sustainable Development Goals (SDGs) established by the United Nations Agenda 2030 constitute a global blueprint agenda and instrument for peace and prosperity... 相似文献
78.
Software Quality Journal - Energy consumption of software has been becoming increasingly significant, since it can vary according to how the software has been developed. In recent years, developers... 相似文献
79.
Alexandre N. Tuch Eva E. Presslaber Markus Stöcklin Klaus Opwis Javier A. Bargas-Avila 《International journal of human-computer studies》2012,70(11):794-811
This paper experimentally investigates the role of visual complexity (VC) and prototypicality (PT) as design factors of websites, shaping users' first impressions by means of two studies. In the first study, 119 screenshots of real websites varying in VC (low vs. medium vs. high) and PT (low vs. high) were rated on perceived aesthetics. Screenshot presentation time was varied as a between-subject factor (50 ms vs. 500 ms vs. 1000 ms). Results reveal that VC and PT affect participants' aesthetics ratings within the first 50 ms of exposure. In the second study presentation times were shortened to 17, 33 and 50 ms. Results suggest that VC and PT affect aesthetic perception even within 17 ms, though the effect of PT is less pronounced than the one of VC. With increasing presentation time the effect of PT becomes as influential as the VC effect. This supports the reasoning of the information-processing stage model of aesthetic processing (Leder et al., 2004), where VC is processed at an earlier stage than PT. Overall, websites with low VC and high PT were perceived as highly appealing. 相似文献
80.
del Campo I Basterretxea K Echanobe J Bosque G Doctor F 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2012,42(2):501-512
This paper presents the development of a neuro-fuzzy agent for ambient-intelligence environments. The agent has been implemented as a system-on-chip (SoC) on a reconfigurable device, i.e., a field-programmable gate array. It is a hardware/software (HW/SW) architecture developed around a MicroBlaze processor (SW partition) and a set of parallel intellectual property cores for neuro-fuzzy modeling (HW partition). The SoC is an autonomous electronic device able to perform real-time control of the environment in a personalized and adaptive way, anticipating the desires and needs of its inhabitants. The scheme used to model the intelligent agent is a particular class of an adaptive neuro-fuzzy inference system with piecewise multilinear behavior. The main characteristics of our model are computational efficiency, scalability, and universal approximation capability. Several online experiments have been performed with data obtained in a real ubiquitous computing environment test bed. Results obtained show that the SoC is able to provide high-performance control and adaptation in a life-long mode while retaining the modeling capabilities of similar agent-based approaches implemented on larger computing machines. 相似文献