全文获取类型
收费全文 | 279349篇 |
免费 | 3041篇 |
国内免费 | 1308篇 |
专业分类
电工技术 | 4814篇 |
综合类 | 521篇 |
化学工业 | 40445篇 |
金属工艺 | 11139篇 |
机械仪表 | 8451篇 |
建筑科学 | 6449篇 |
矿业工程 | 1585篇 |
能源动力 | 6990篇 |
轻工业 | 22566篇 |
水利工程 | 3043篇 |
石油天然气 | 5785篇 |
武器工业 | 43篇 |
无线电 | 33587篇 |
一般工业技术 | 56597篇 |
冶金工业 | 51227篇 |
原子能技术 | 7497篇 |
自动化技术 | 22959篇 |
出版年
2021年 | 2164篇 |
2019年 | 2072篇 |
2018年 | 3586篇 |
2017年 | 3675篇 |
2016年 | 3910篇 |
2015年 | 2492篇 |
2014年 | 4363篇 |
2013年 | 11996篇 |
2012年 | 7084篇 |
2011年 | 9736篇 |
2010年 | 7553篇 |
2009年 | 8768篇 |
2008年 | 9120篇 |
2007年 | 9167篇 |
2006年 | 7824篇 |
2005年 | 7278篇 |
2004年 | 7215篇 |
2003年 | 6999篇 |
2002年 | 6731篇 |
2001年 | 6857篇 |
2000年 | 6499篇 |
1999年 | 6786篇 |
1998年 | 16418篇 |
1997年 | 11663篇 |
1996年 | 8954篇 |
1995年 | 6877篇 |
1994年 | 6044篇 |
1993年 | 6081篇 |
1992年 | 4412篇 |
1991年 | 4196篇 |
1990年 | 4083篇 |
1989年 | 4063篇 |
1988年 | 3765篇 |
1987年 | 3403篇 |
1986年 | 3400篇 |
1985年 | 3767篇 |
1984年 | 3475篇 |
1983年 | 3229篇 |
1982年 | 3040篇 |
1981年 | 3051篇 |
1980年 | 3046篇 |
1979年 | 2844篇 |
1978年 | 2889篇 |
1977年 | 3166篇 |
1976年 | 4131篇 |
1975年 | 2430篇 |
1974年 | 2397篇 |
1973年 | 2408篇 |
1972年 | 2032篇 |
1971年 | 1788篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Zhang Sheng-ming Yangtze River Scientific Research Institute Wuhan Hubei P. R. China 《水动力学研究与进展(B辑)》1992,(2)
Through a series of model tests of five scales for 2-D free hydraulic jump, the da-ta of fluctuating pressure acting on the floor level within the hydraulic jump were obtained. Dur-ing the experiments, Froude number varied from 2.94 to 8.61, and Reynolds number rangedfrom 2×10~4 to 6×10~5. Experiment results indicate that the amplitude scale of fluctuating pres-sure is the length scale of model, i. e. P'=L, which agrees with gravity similarity law: Thefrequency scale of the fluctuating pressure is a unity i. e., f=1, which does not satisfy thegravity similarity law. 相似文献
992.
The interstitial assemblages of the River Rhine were studied in the Rhinau sector (France). The studied area is located in aVegulated channel of the river, controlled by a hydroelectric dam. Twenty stations were sampled in September 1988. Ten litres of interstitial water were pumped at 50 cm depth in each station using the Bou-Rouch technique. Interstitial waters were poorly oxygenated and the hyporheic fauna had three major characteristics: (1) microcrustaceans were dominant, (2) the insects were rare and (3) the stygofauna was absent. The richest stations were well oxygenated and did not correspond to any particular geomorphological features. These findings contrast with the situation observed on other large European rivers (Rhǒne, Danube) where the interstitial assemblages appear to be locally more diversified and rich in stygofauna. 相似文献
993.
994.
Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 1, p. 32, January, 1992. 相似文献
995.
Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 10, pp. 8–10, October, 1992. 相似文献
996.
997.
998.
999.
1000.
Face to virtual face 总被引:1,自引:0,他引:1
Thalmann N.M. Kalra P. Escher M. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1998,86(5):870-883
The first virtual humans appeared in the early 1980s in such films as Dreamflight (1982) and The Juggler (1982). Pioneering work in the ensuing period focused on realistic appearance in the simulation of virtual humans. In the 1990s, the emphasis has shifted to real-time animation and interaction in virtual worlds. Virtual humans have begun to inhabit virtual worlds and so have we. To prepare our place in the virtual world we first develop techniques for the automatic representation of a human face capable of being animated in real time using both video and audio input. The objective is for one's representative to look, talk, and behave like oneself in the virtual world. Furthermore, the virtual inhabitants of this world should be able to see our avatars and to react to what we say and to the emotions we convey. We sketch an overview of the problems related to the analysis and synthesis of face-to-virtual-face communication in a virtual world. We describe different components of our system for real-time interaction and communication between a cloned face representing a real person and an autonomous virtual face. It provides an insight into the various problems and gives particular solutions adopted in reconstructing a virtual clone capable of reproducing the shape and movements of the real person's face. It includes the analysis of the facial expression and speech of the cloned face, which can be used to elicit a response from the autonomous virtual human with both verbal and nonverbal facial movements synchronized with the audio voice 相似文献