全文获取类型
收费全文 | 2749篇 |
免费 | 94篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 12篇 |
化学工业 | 668篇 |
金属工艺 | 26篇 |
机械仪表 | 24篇 |
建筑科学 | 148篇 |
矿业工程 | 5篇 |
能源动力 | 53篇 |
轻工业 | 510篇 |
水利工程 | 20篇 |
石油天然气 | 6篇 |
无线电 | 107篇 |
一般工业技术 | 419篇 |
冶金工业 | 585篇 |
原子能技术 | 7篇 |
自动化技术 | 255篇 |
出版年
2023年 | 20篇 |
2022年 | 49篇 |
2021年 | 83篇 |
2020年 | 45篇 |
2019年 | 39篇 |
2018年 | 60篇 |
2017年 | 50篇 |
2016年 | 62篇 |
2015年 | 47篇 |
2014年 | 70篇 |
2013年 | 172篇 |
2012年 | 175篇 |
2011年 | 187篇 |
2010年 | 166篇 |
2009年 | 147篇 |
2008年 | 159篇 |
2007年 | 155篇 |
2006年 | 108篇 |
2005年 | 121篇 |
2004年 | 92篇 |
2003年 | 98篇 |
2002年 | 89篇 |
2001年 | 48篇 |
2000年 | 37篇 |
1999年 | 46篇 |
1998年 | 42篇 |
1997年 | 54篇 |
1996年 | 52篇 |
1995年 | 33篇 |
1994年 | 32篇 |
1993年 | 25篇 |
1992年 | 29篇 |
1991年 | 17篇 |
1990年 | 27篇 |
1989年 | 22篇 |
1988年 | 14篇 |
1987年 | 14篇 |
1986年 | 19篇 |
1985年 | 17篇 |
1984年 | 15篇 |
1983年 | 13篇 |
1982年 | 14篇 |
1980年 | 10篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 10篇 |
1976年 | 6篇 |
1975年 | 6篇 |
1973年 | 6篇 |
1948年 | 3篇 |
排序方式: 共有2845条查询结果,搜索用时 15 毫秒
11.
The flow structure of a continuous‐flow reactor stirred by a Rushton turbine was investigated by laser Doppler velocimetry for two different mean residence time‐mixing time ratios. Velocity measurements were obtained for two inlet locations, corresponding to the incoming liquid stream being fed co‐currently or counter‐currently to the flow discharged by the turbine. In all investigated configurations and for all operating conditions, it was found that the flow disruption caused by the incoming liquid stream was observable mainly in the first vessel quarter, which followed the feed‐tube plane. From comparison of the velocities encountered in the various planes in the continuous‐flow reactor to the velocities of the batch reactor, it was also concluded that it may be possible to intensify the usage of the turbine‐stirred vessel by decreasing the characteristic times ratio, without considerable flow by‐pass and/or short‐circuiting problems. 相似文献
12.
Havasi Catherine Speer Robert Pustejovsky James Lieberman Henry 《Intelligent Systems, IEEE》2009,24(4):24-35
Understanding the world we live in requires access to a large amount of background knowledge: the commonsense knowledge that most people have and most computer systems don't. Many of the limitations of artificial intelligence today relate to the problem of acquiring and understanding common sense. The Open Mind Common Sense project began to collect common sense from volunteers on the Internet starting in 2000. The collected information is converted to a semantic network called ConceptNet. Reducing the dimensionality of ConceptNet's graph structure gives a matrix representation called AnalogySpace, which reveals large-scale patterns in the data, smoothes over noise, and predicts new knowledge. Extending this work, we have created a method that uses singular value decomposition to aid in the integration of systems or representations. This technique, called blending, can be harnessed to find and exploit correlations between different resources, enabling commonsense reasoning over a broader domain. 相似文献
13.
The objective of this paper is to propose an architecture for aCAble TeleVision (CATV) network, capable of supporting two-way transmission. This evolution is necessary for the survival of the CATV industry in an era of deregulation and of the development of the B-ISDN by the telecommunications companies. A communication transactional service is then considered and performance analysis is done under realistic assumptions. 相似文献
14.
Ulrich Schmatz Catherine Dubourdieu Oleg Lebedev Gerard Delabouglise Francois Weiss Jean-Pierre Senateur 《Journal of Low Temperature Physics》1996,105(5-6):1301-1306
Thin and thick YBCO Films have been grown by Aerosol Assisted as well as by thermal MOCVD. The Aerosol Assisted MOCVD technique allows the growth of YBCO films from a single liquid source at deposition rates of up to 10m/h.Transport measurements (I-V) on etched microbridges using a single pulse technique have been performed. The angular magnetic field dependence Jc() of the critical current density from Tc down to 50 K has been measured. Transport properties are reported and discussed with respect to the microstructural features as determined by X-ray diffraction and electron microscopy. 相似文献
15.
Baptiste Demey Marine Bentz Vronique Descamps Virginie Morel Catherine Francois Sandrine Castelain Francois Helle Etienne Brochot 《International journal of molecular sciences》2022,23(13)
Background: Bkv-miR-B1-5p is a viral micro-RNA (miRNA) specifically produced during BK polyomavirus (BKPyV) replication. Recent studies have suggested using bkv-miR-B1-5p as a biomarker to monitor viral infection and predict complications in kidney transplant patients. To identify the technical limitations of this miRNA quantification in biological samples, knowledge of its stability and distribution in the extracellular compartment is necessary. Moreover, a proof of concept for using bkv-miR-B1-5p as a biomarker of active replication in chronic infection is still missing in the published literature. Methods: The stability of bkv-miR-B1-5p was evaluated in samples derived from cell cultures and in urine from BKPyV-infected kidney transplant recipients. The miRNA was quantified in different fractions of the extracellular compartment, including exosomes, and protein binding was evaluated. Finally, we developed an in vitro model for chronic culture of BKPyV clinical isolates to observe changes in the bkv-miR-B1-5p level during persistent infections. Results: Bkv-miR-B1-5p is a stable biomarker in samples from humans and in vitro experiments. Marginally associated with the exosomes, most of the circulating bkv-miR-B1-5p is bound to proteins, especially Ago2, so the miRNA quantification does not require specific exosome isolation. The bkv-miR-B1-5p level is predictable of viral infectivity, which makes it a potential specific biomarker of active BKPyV replication after kidney transplantation. 相似文献
16.
Ben Shneiderman Catherine Plaisant Rodrigo Botafogo Don Hopkins William Weiland 《New Review of Hypermedia and Multimedia》2013,19(2):101-117
Since browsing hypertext can present a formidable cognitive challenge, user interface design plays a major role in determining acceptability. In the Unix workstation version of Hyperties, a research-oriented prototype, we focussed on design features that facilitate browsing. We first give a general overview of Hyperties and its markup language. Customizable documents can be generated by the conditional text feature that enables dynamic and selective display of text and graphics. In addition we present: — an innovative solution to link identification: pop-out graphical buttons of arbitrary shape. — application of pie menus to permit low cognitive load actions that reduce the distraction of common actions, such as page turning or window selection. — multiple window selection strategies that reduce clutter and housekeeping effort. We preferred piles-of-tiles, in which standard-sized windows were arranged in a consistent pattern on the display and actions could be done rapidly, allowing users to concentrate on the contents. 相似文献
17.
S. Manoj Kumar N. Rajkumar W. Catherine Christinal Mary 《Wireless Personal Communications》2013,70(4):1697-1709
In Wireless Sensor Network (WSN) sensors are densely deployed where the intruders can compromise some sensor nodes and inject false data in order to raise false alarms, reduce network lifetime, utilize bandwidth resources and so on. False Data Injection can possibly occur in Data Aggregation (DA) and Data Forwarding (DF). This paper analyses EFDD Protocol-Early False Data Detection Protocol which addresses the two possibilities in a simple and secure way considering the constraints of sensor nodes. The main idea is the selection of the network structure; this protocol will work effectively in Spatial/Semantic Correlation Tree Structure (SCT). False Data Detection in DA is done using some monitoring nodes which will monitor the Data Aggregator. EFDD in SCT structure reduce the counterfeit data transmission when compared to other structure in a better way. The result shows that EFDD reduce data transmission by dropping false data earlier and it also reduces computation when compared to the existing schemes. 相似文献
18.
Catherine Le Corre-Guimard M’hamed Drissi Jacques Citerne Pierre Morillon 《电信纪事》1997,52(5-6):293-305
The high integration level associated to the increase of the operating frequency of microelectronic integrated circuits create complex electromagnetic coupling in the interconnection lines which lead to mismatch and frequency dispersion. In the present paper, we propose a full-wave analysis to characterise the electromagnetic behaviour of interconnection planar lines using mixed-potential integral equations technique. The theoretical and numerical treatments of Green’s functions for the specific structures are firstly presented. The calculated results for parallel and coplanar strips are compared to the published ones. The effect of the finite ground plane on the propagation constant and the characteristic impedance is then analysed for different permittivities. The obtained theoretical and experimental results for the reflection coefficient of straight resonators confirm finally the observed effect of the finite ground plane on the frequency dispersion and the scattering characteristics. 相似文献
19.
Cooney CM 《Environmental science & technology》1996,30(9):387A
Society. 相似文献
20.
Cooney CM 《Environmental science & technology》1996,30(5):195A-196A
Government. 相似文献