全文获取类型
收费全文 | 15396篇 |
免费 | 2714篇 |
国内免费 | 1836篇 |
专业分类
电工技术 | 1082篇 |
技术理论 | 1篇 |
综合类 | 2445篇 |
化学工业 | 551篇 |
金属工艺 | 267篇 |
机械仪表 | 922篇 |
建筑科学 | 678篇 |
矿业工程 | 430篇 |
能源动力 | 223篇 |
轻工业 | 420篇 |
水利工程 | 410篇 |
石油天然气 | 383篇 |
武器工业 | 266篇 |
无线电 | 1944篇 |
一般工业技术 | 763篇 |
冶金工业 | 658篇 |
原子能技术 | 37篇 |
自动化技术 | 8466篇 |
出版年
2024年 | 66篇 |
2023年 | 333篇 |
2022年 | 570篇 |
2021年 | 594篇 |
2020年 | 517篇 |
2019年 | 432篇 |
2018年 | 360篇 |
2017年 | 466篇 |
2016年 | 528篇 |
2015年 | 558篇 |
2014年 | 828篇 |
2013年 | 777篇 |
2012年 | 1096篇 |
2011年 | 1192篇 |
2010年 | 987篇 |
2009年 | 1018篇 |
2008年 | 1170篇 |
2007年 | 1385篇 |
2006年 | 1135篇 |
2005年 | 983篇 |
2004年 | 816篇 |
2003年 | 753篇 |
2002年 | 677篇 |
2001年 | 553篇 |
2000年 | 476篇 |
1999年 | 366篇 |
1998年 | 266篇 |
1997年 | 202篇 |
1996年 | 178篇 |
1995年 | 135篇 |
1994年 | 133篇 |
1993年 | 84篇 |
1992年 | 52篇 |
1991年 | 56篇 |
1990年 | 41篇 |
1989年 | 28篇 |
1988年 | 22篇 |
1987年 | 13篇 |
1986年 | 11篇 |
1985年 | 13篇 |
1984年 | 14篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1966年 | 5篇 |
1964年 | 7篇 |
1963年 | 4篇 |
1962年 | 4篇 |
1961年 | 4篇 |
1957年 | 4篇 |
1956年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 890 毫秒
71.
通过正确分析岩土施工成本的价格体现和存在问题 ,对实现成本效益做出科学评价 ,并提出降低岩土施工成本的途径 相似文献
72.
A. Rac 《Tribology International》1985,18(1):29-33
The wear of grey cast iron in dry sliding conditions has been studied with the aims of (1) finding the influence of working conditions on the wear rate, and (2) determining the region of speed and load where low wear is accomplished. Grey cast iron with flake and nodular graphite was submitted to investigation using a pin-on-disc machine. The results indicate that the flake graphite cast iron is more suitable for applications at speeds greater than 4 m s−1 and lower loads, while nodular cast iron has greater wear resistance at lower speeds in the range of loads investigated - from 50 N cm−2 to 200 N cm−2 相似文献
73.
本文根据P.N.T.Unwin和R.Henderson等人提出的对生物大分子晶体的囹象处理方法,对无染色的牛肝过氧化氢酶薄晶的显微象和衍射图进行了图象处理,最后得到了牛肝过氧化氢酶薄晶的二维结构。从中可以看出,牛肝过氧化氢酶薄晶的一个单胞由4个子胞组成,4个子胞排列方向各异。 相似文献
74.
考虑Hopfield模型中假态之间的布尔逻辑关系,提出利用IPA模型对神经网络中的假态进行抑制,并和原网络的性能进行了比较,结果表明:改进后的网络性能比Hopfield模型和IPA模型均有较大提高。 相似文献
75.
The aim of this study was to demonstrate a correlation between the clinical assessment of narcissistic personality disorder in children and underlying self and object relationships. D. Westen's Social Cognition and Object Relations Scale for the Thematic Apperception Test (1995; D. Westen, N. Lohr, K. Silk, K. Kerber, & S. Goodrich, 1985) was used to compare the object representations of two groups of referred latency-aged children, one for whom narcissistic issues were thought to be primary. Support for the clinical literature, which describes these children as lacking in empathy, struggling with self-esteem regulation, and in poor control of their impulses or aggression, was found. Additionally, a tendency to have a vulnerable sense of identity and to be preoccupied with seeking out and developing relationships with others was found to differentiate these children from peers with similar behavioral and diagnostic profiles. Results obtained have potential implications for the assessment and treatment of narcissistically disturbed children. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
76.
Before 12 months of age, infants have difficulties coordinating and sequencing their movements to retrieve an object concealed in a box. This study examined (a) whether young infants can discover effective retrieval solutions and consolidate movement coordination earlier if exposed regularly to such a task and (b) whether different environments, indexed by box transparency, would impact the rate of learning and time of discovery of these solutions. Infants (N=12) were presented with an object retrieval task every week from 6 1/2 months of age until they were able to retrieve the toy from the box using coordinated two-handed patterns for 3 weeks. To reach that criterion, infants tested with an opaque box took 2 1/2 months and infants tested with a semitransparent box took 1 1/2 months. Both groups outperformed age-matched controls who received a one-time exposure to the task. Repeated exposure to the task and vision of the toy significantly enhanced this process of solution discovery. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
77.
����ѡ������Ļ�ɫ���߷��� 总被引:2,自引:0,他引:2
本文根据灰色系统理论中的灰色决策原理,提出了一种合理选择钻机的新方法,并通过了实例验证。结果表明,这种方法切实可行。 相似文献
78.
Human can handle a deformable object and damp its vibration with recognized skill. However, for an industrial robot, handling a deformable object with acute vibration is often a difficult task. This paper addresses the problem of active damping skill for handling deformable linear objects (DLOs) by using a strategy inspired from human manipulation skills. The strategy is illustrated by several rules, which are explained by a fuzzy and a P controller. A proportional-integral-derivative (PID) controller is also employed to explain the rules as a comparison. The interpretations from controllers are translated into high level commands in a robotic language V+. A standard industrial robot with a force/torque sensor mounted on the wrist was employed to demonstrate the skill. Experimental results showed the fuzzy based damping skill is quite effective and stable even without any previous acknowledge of the deformable linear objects.Category (5) 相似文献
79.
William Kent 《Computer Standards & Interfaces》1991,13(1-3):201-206
OSQL is the object-oriented database language developed for the Iris object-oriented database management system at Hewlett-Packard Laboratories. Its three fundamental constructs are objects, types, and functions. This paper provides an overview of the underlying concepts and some important features of OSQL. 相似文献
80.
论校园文化和德育目标的一致性 总被引:3,自引:0,他引:3
冯峰 《河南机电高等专科学校学报》2002,10(1):13-14
中系统介绍了校园化和德育目标的关系,并找准两之间的结合点,通过分析两的一致性和辩证统一关系,达到育人目的。 相似文献