全文获取类型
收费全文 | 2255篇 |
免费 | 175篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 49篇 |
综合类 | 1篇 |
化学工业 | 634篇 |
金属工艺 | 25篇 |
机械仪表 | 48篇 |
建筑科学 | 83篇 |
矿业工程 | 3篇 |
能源动力 | 63篇 |
轻工业 | 250篇 |
水利工程 | 15篇 |
石油天然气 | 1篇 |
无线电 | 233篇 |
一般工业技术 | 385篇 |
冶金工业 | 148篇 |
原子能技术 | 10篇 |
自动化技术 | 485篇 |
出版年
2024年 | 3篇 |
2023年 | 39篇 |
2022年 | 124篇 |
2021年 | 151篇 |
2020年 | 90篇 |
2019年 | 96篇 |
2018年 | 99篇 |
2017年 | 77篇 |
2016年 | 108篇 |
2015年 | 77篇 |
2014年 | 131篇 |
2013年 | 172篇 |
2012年 | 168篇 |
2011年 | 176篇 |
2010年 | 122篇 |
2009年 | 91篇 |
2008年 | 109篇 |
2007年 | 92篇 |
2006年 | 78篇 |
2005年 | 76篇 |
2004年 | 49篇 |
2003年 | 41篇 |
2002年 | 33篇 |
2001年 | 17篇 |
2000年 | 11篇 |
1999年 | 20篇 |
1998年 | 47篇 |
1997年 | 24篇 |
1996年 | 23篇 |
1995年 | 15篇 |
1994年 | 9篇 |
1993年 | 12篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1968年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有2433条查询结果,搜索用时 0 毫秒
1.
2.
Luigi Lazzeri Maria Grazia Cascone Simone Quiriconi Letterio Morabito Paolo Giusti 《Polymer International》2005,54(1):101-107
Biodegradable hollow microfibres containing particles loaded with specific active agents can be potentially employed to produce a special kind of substrate for tissue engineering, able to function as a scaffold and at the same time to act as a drug‐releasing system. Biodegradable hollow microfibres based on poly(lactic acid) were produced by a dry–wet spinning procedure. Drug‐loaded microparticles were prepared by a simple oil‐in‐water emulsion and entrapped inside the fibres. The morphology of both fibres and particles was investigated by scanning electron microscopy. The mechanical and thermal properties of the fibres were investigated by tensile tests and differential scanning calorimetry. In vitro tests were performed to evaluate the release of the drug from the fibres loaded with the particles Copyright © 2004 Society of Chemical Industry 相似文献
3.
R Santinelli C Tolone R Toraldo G Canino A De Simone M D'Avanzo 《Canadian Metallurgical Quarterly》1998,55(6):854-856
OBJECTIVE: To describe a mother and her 2 sons affected by idiopathic intracranial hypertension (IIH), associated in the sons with root irritation symptom. Unlike the other 4 families reported previously, obesity was not present in our patients. DESIGN: Case reports. SETTING: Department of pediatrics in a university school of Medicine, Naples, Italy. PATIENTS: A mother (aged 36 years) and her 2 sons (aged 14 and 9 years) developed IIH at different times. Neuroimaging showed an empty sella in the mother, while IIH was associated with spinal and radicular pain in her 2 sons. The mother and the younger son developed permanent visual loss. CONCLUSIONS: Ophthalmologic follow-up in our patients indicates that IIH is a chronic disease. Surgical treatment should be considered an option. 相似文献
4.
Alberto Carpinteri Bernardino Chiaia Simone Puzzi 《Engineering Fracture Mechanics》2007,74(17):2892-2896
Aim of this letter to the Editor is at replying to the criticisms raised by Ba?ant and Yavari [Ba?ant ZP, Yavari A. Is the cause of size effect on structural strength fractal or energetic - statistical? Engng Fract Mech 2005;72:1-31] against the fractal approach to the size-scale effects on the mechanical properties of materials and the concept of the Multi-Fractal Scaling Law presented by Carpinteri [Carpinteri A. Scaling laws and renormalization groups for strength and toughness of disordered materials. Int J Solids Struct 1994;31:291-302]. These criticisms will be analysed thoroughly, showing how they also contain some mistakes and misunderstandings. The presented elucidations should redirect the discussion to a more correct scientific debate. 相似文献
5.
Dario Pasini Luigi Garlaschelli Elza Bontempi Laura E. Depero 《Fullerenes, Nanotubes and Carbon Nanostructures》2007,15(5):367-378
The synthesis of a series of polymers and cyclopolymers bearing crown ethers of differing structure and affinities towards primary ammonium ions is discussed. These polymers have been tested in their efficiency to form structurally homogeneous thin films when blended with an amphiphilic C60 compound containing a primary ammonium ion functional group. The X-ray reflectivity characterization of the films revealed that the polymer bearing the crown ether with the least affinity for primary ammonium ions, but having the highest degree of polymerization, is the most effective in forming structurally homogeneous thin films. 相似文献
6.
To clarify whether motion information per se has a separable influence on action control, the authors investigated whether irrelevant direction of motion of stimuli whose overall position was constant over time would affect manual left-right responses (i.e., reveal a motion-based Simon effect). In Experiments 1 and 2, significant Simon effects were obtained for sine-wave gratings moving in a stationary Gaussian window. In Experiment 3, a direction-based Simon effect with random-dot patterns was replicated, except that the perceived direction of motion was based on the displacement of single elements. Experiments 4 and 5 studied motion-based Simon effects to point-light figures that walked in place--displays requiring high-level analysis of global shape and local motion. Motion-based Simon effects occurred when the displays could be interpreted as an upright human walker, showing that a high-level representation of motion direction mediated the effects. Thus, the present study establishes links between high-level motion perception and action. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
From "macro" to "micro" manipulation: models and experiments 总被引:1,自引:0,他引:1
A. Menciassi A. Eisinberg I. Izzo P. Dario 《Mechatronics, IEEE/ASME Transactions on》2004,9(2):311-320
This paper addresses various problems related to manipulation in the micro domain, a field which is increasingly important for research and application. Grasping and manipulating parts with size ranging between a few micrometers and about 1 millimeter (defined in this paper as "micro parts") are required for an increasing number of applications: the assembly of micro systems and micro machines; and the operation in tiny and unpredictable environments, such as for inspection and interventions in pipes and for micro surgery. The aim of this work is to find out similarities and differences between traditional manipulation and micro manipulation, by investigating which requirements are still valid and which must be redefined when the object size scales down. The similarities between the two application domains "macro" and "micro" are pointed out along with the differences, and both are taken into account for the evaluation of different grasping typologies. Dedicated models for the adhesion forces arising at the micro level are presented, preliminarily tested, and discussed. 相似文献
8.
Tungsten oxide and molybdenum doped tungsten oxide electrochromic films have been electrochemically prepared from a metal peroxide bath and experimentally tested. They were characterized by electrical and optical methods, using cyclic voltammograms and calculating the charge capacity as a function of the number of deposition cycles.The color of the electrochromic WO3 film is strongly altered by doping it with molybdenum. Electrochromic W---Mo oxide films were fabricated by adding different percentages of molybdenum to tungsten oxide, ranging from 0.5% to 7% weight of deposition solution. Normal optical transmittance was also measured and evidence is given of different behavior if the switching for oxidation and reduction cycle, so that coloration occurs in a shorter time than the bleaching. The time constant of the process tends to increase as a function of the molybdenum oxide doping concentration. 相似文献
9.
Leonardo Badia Andrea Baiocchi Alfredo Todini Simone Merlin Silvano Pupolin Andrea Zanella Michele Zorzi 《Wireless Communications, IEEE》2007,14(1):36-43
Multicellular networks based on the IEEE 802.16 standard appear to be very promising candidates to provide end users with broadband wireless access. However, they also pose interesting challenges in terms of radio resource management, where several design choices are not specified in the standard, intentionally left open to implementors. For this reason, we focus in this article on scheduling and resource allocation, and investigate how they could operate in a cross-layer fashion. In particular, we describe the principles of joint scheduling and resource allocation for IEEE 802.16 operating in AMC mode, and discuss the critical role played by physical layer considerations, especially intercell interference estimation and channel state awareness, in the obtained performance. This leads to identifying key open issues and possible general solutions 相似文献
10.
Electrostatic destabilization of water-in-crude oil emulsions: Application to a real case and evaluation of the Aibel VIEC technology 总被引:1,自引:0,他引:1
In the current study, the Aibel Vessel Internal Electrostatic Coalescer (VIEC) technology was tested for a real case scenario encountered in the production train of a UK oil field. Depressurized samples were collected both upstream and downstream of the first stage separator. The separation performance was discussed with respect to water cut and droplet size distribution of the emulsions, and the effect of chemical treatment. Issues with respect to representative sampling and testing have been discussed. The application of an external AC electrical field has been shown to significantly enhance the separation of the aqueous phase from tight emulsions, both when it was used alone and in combination with a commercial demulsifier. By using the VIEC technology, the time for separation could be reduced from 8 min to 2 min and the overall BS&W in the emulsions was improved from 45% or 60% to a residual water content of 5-20%. Destabilization of a 45% water-in-oil emulsion by electrical and chemical treatment (20/40 ppm) produced oil in the 2-7% BS&W range whereas the corresponding tests without applying an electrostatic field led to a BS&W greater than 25%. The achieved results strongly suggest that the VIEC technology can resolve the stable emulsion bands encountered in the Schiehallion train and add flexibility or increased production rate to the process. The results also suggest the importance of further studies on the destabilization performances achieved by electrostatic means. 相似文献