全文获取类型
收费全文 | 51081篇 |
免费 | 1382篇 |
国内免费 | 189篇 |
专业分类
电工技术 | 635篇 |
综合类 | 668篇 |
化学工业 | 6669篇 |
金属工艺 | 798篇 |
机械仪表 | 1038篇 |
建筑科学 | 1421篇 |
矿业工程 | 411篇 |
能源动力 | 682篇 |
轻工业 | 2863篇 |
水利工程 | 678篇 |
石油天然气 | 91篇 |
武器工业 | 5篇 |
无线电 | 2465篇 |
一般工业技术 | 4761篇 |
冶金工业 | 21915篇 |
原子能技术 | 242篇 |
自动化技术 | 7310篇 |
出版年
2023年 | 266篇 |
2022年 | 267篇 |
2021年 | 422篇 |
2020年 | 198篇 |
2019年 | 250篇 |
2018年 | 728篇 |
2017年 | 904篇 |
2016年 | 1354篇 |
2015年 | 1001篇 |
2014年 | 751篇 |
2013年 | 1029篇 |
2012年 | 2573篇 |
2011年 | 3007篇 |
2010年 | 1079篇 |
2009年 | 1227篇 |
2008年 | 1039篇 |
2007年 | 1020篇 |
2006年 | 887篇 |
2005年 | 3607篇 |
2004年 | 2805篇 |
2003年 | 2283篇 |
2002年 | 1026篇 |
2001年 | 865篇 |
2000年 | 407篇 |
1999年 | 723篇 |
1998年 | 6268篇 |
1997年 | 3926篇 |
1996年 | 2591篇 |
1995年 | 1524篇 |
1994年 | 1141篇 |
1993年 | 1179篇 |
1992年 | 300篇 |
1991年 | 360篇 |
1990年 | 362篇 |
1989年 | 340篇 |
1988年 | 340篇 |
1987年 | 266篇 |
1986年 | 247篇 |
1985年 | 219篇 |
1984年 | 130篇 |
1983年 | 124篇 |
1982年 | 165篇 |
1981年 | 212篇 |
1980年 | 230篇 |
1979年 | 91篇 |
1978年 | 131篇 |
1977年 | 641篇 |
1976年 | 1357篇 |
1975年 | 137篇 |
1973年 | 82篇 |
排序方式: 共有10000条查询结果,搜索用时 358 毫秒
101.
E St?lberg S St?lberg M Melander K Arimura 《Computer methods and programs in biomedicine》1991,34(2-3):219-227
Programs for rule based electromyography (EMG) interpretation and reporting are described. A number of parameters are obtained during an EMG investigation. The combination of these data leads to a neurophysiological conclusion. Knowledge from the literature, research and experience is the basis for rule development. Rules have been developed for 14 of the most commonly used classifications of an EMG. The syntax is relatively easy and the user may change the rules, add rules or apply the system for other types of data. The results are displayed in a new graphical way. The system presented here is part of an integrated EMG laboratory with administrative routines, distributed databases for storage of results and routines for automatic report generation. 相似文献
102.
Cristina Ca?ero Nikolaos Thomos George A Triantafyllidis George C Litos Michael Gerassimos Strintzis 《IEEE transactions on information technology in biomedicine》2005,9(1):44-49
Ultrasound imaging allows the evaluation of the degree of emergency of a patient. However, in some instances, a well-trained sonographer is unavailable to perform such echography. To cope with this issue, the Mobile Tele-Echography Using an Ultralight Robot (OTELO) project aims to develop a fully integrated end-to-end mobile tele-echography system using an ultralight remote-controlled robot for population groups that are not served locally by medical experts. This paper focuses on the user interface of the OTELO system, consisting of the following parts: an ultrasound video transmission system providing real-time images of the scanned area, an audio/video conference to communicate with the paramedical assistant and with the patient, and a virtual-reality environment, providing visual and haptic feedback to the expert, while capturing the expert's hand movements. These movements are reproduced by the robot at the patient site while holding the ultrasound probe against the patient skin. In addition, the user interface includes an image processing facility for enhancing the received images and the possibility to include them into a database. 相似文献
103.
104.
105.
Farzaneh Fayazpour Bart Lucas Roosmarijn E. Vandenbroucke Stefaan Derveaux Jan Tavernier Sam Lievens Joseph Demeester Stefaan C. De Smedt 《Advanced functional materials》2008,18(18):2716-2723
To obtain more biologically relevant data there is a growing interest in the use of living cells for assaying the biological activity of unknown chemical compounds. Density ‘multiplex’ cell‐based assays, where different cell types are mixed in one well and simultaneously investigated upon exposure to a certain compound are beginning to emerge. To be able to identify the cells they should be attached to microscopic carriers that are encoded. This paper investigates how digitally encoded microparticles can be loaded with cells while keeping the digital code in the microcarriers readable. It turns out that coating the surface of the encoded microcarriers with polyelectrolytes using the layer‐by‐layer (LbL) approach provides the microcarriers with a ‘highly functional’ surface. The polyelectrolyte layer allows the growth of the cells, allows the orientation of the cell loaded microcarriers in a magnetic field, and does not hamper the reading of the code. It has further been shown that the cells growing on the polyelectrolyte layer can become transduced by adenoviral particles hosted by the polyelectrolyte layer. It is concluded that the digitally encoded microparticles are promising materials for use in biomedical and pharmaceutical in‐vitro research where cells are used as tools. 相似文献
106.
Optimal and reinforced robustness designs of fuzzy variable structure tracking control for a piezoelectric actuator system 总被引:1,自引:0,他引:1
In this paper, a piezoelectric actuator (PEA) system is approximated by N subsystems, which are described by pulse transfer functions. The approximation error between the PEA system and the fuzzy linear pulse transfer function system is represented by additive nonlinear time-varying uncertainties in every subsystem. First, a dead-beat to the switching surface for every ideal subsystem is designed. It is called the "variable structure tracking control". The output disturbance of the ith subsystem is caused by the approximation error of fuzzy-model and the interaction dynamics resulting from other subsystems. In general, it is not small. Then, the H/sup /spl infin//-norm of the sensitivity function between the switching surface and the output disturbance is minimized. It is the "optimal robustness". Although the effect of the output disturbance is attenuated, a better performance can be reinforced by a switching control which is based on the Lyapunov redesign. This is the final step for the robustness design of control, which is "reinforced robustness". The stability of the overall system is verified by Lyapunov stability theory. Experimental work of a PEA system was carried out to confirm the validity of the proposed control. 相似文献
107.
108.
Pulkki-R?back Laura; Elovainio Marko; Kivim?ki Mika; Raitakari Olli T.; Keltikangas-J?rvinen Liisa 《Canadian Metallurgical Quarterly》2005,24(3):307
This study examined associations of temperament at ages 6 to 12 with body-mass index (BMI) and waist circumference (WC) at ages 24 to 30 years. The participants were 619 men and women derived from the population-based Cardiovascular Risk in Young Finns Study. Temperament was operationalized as (negative) emotionality, sociability, and activity. High emotionality predicted increased BMI, independently of WC, and independently of childhood and adulthood risk factors for adult obesity. None of the temperament dimensions had any associations with WC after controlling for BMI. The findings suggest that temperamental difficulty in childhood may be a useful risk indicator for general body mass in adulthood, and the mechanisms relating temperament with body mass should be further explored. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
109.
110.
Motivated by a study of similar problems stated for factors of words, we study forbidden subwords of a language or a word. A procedure for obtaining the set of all words avoiding a given set of subwords is presented. On the other hand, an algorithm for computing the set of minimal forbidden subwords for a word is given. The case of a two-letter alphabet appears to be particularly interesting and it is considered separately. 相似文献