全文获取类型
收费全文 | 546篇 |
免费 | 19篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 7篇 |
综合类 | 1篇 |
化学工业 | 129篇 |
金属工艺 | 20篇 |
机械仪表 | 15篇 |
建筑科学 | 10篇 |
矿业工程 | 1篇 |
能源动力 | 14篇 |
轻工业 | 59篇 |
水利工程 | 3篇 |
石油天然气 | 3篇 |
无线电 | 68篇 |
一般工业技术 | 142篇 |
冶金工业 | 25篇 |
原子能技术 | 1篇 |
自动化技术 | 71篇 |
出版年
2023年 | 5篇 |
2022年 | 16篇 |
2021年 | 23篇 |
2020年 | 16篇 |
2019年 | 15篇 |
2018年 | 21篇 |
2017年 | 18篇 |
2016年 | 35篇 |
2015年 | 16篇 |
2014年 | 25篇 |
2013年 | 39篇 |
2012年 | 22篇 |
2011年 | 35篇 |
2010年 | 28篇 |
2009年 | 29篇 |
2008年 | 20篇 |
2007年 | 18篇 |
2006年 | 15篇 |
2005年 | 7篇 |
2004年 | 7篇 |
2003年 | 9篇 |
2002年 | 7篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 13篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 11篇 |
1991年 | 5篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有569条查询结果,搜索用时 15 毫秒
1.
Development of nano indium tin oxide (ITO) grains by alkaline hydrolysis of In(III) and Sn(IV) salts
Indium tin oxide (ITO) nano powders of different compositions (In: Sn = 90: 10, 70: 30 and 50: 50) were prepared by heat treatment
(300-450°C) of mixed hydroxides of In(III) and Sn(IV). The hydroxides were obtained by the reaction of aq. NH3 with mixed aq. solutions of In(NO3)3 and SnCl4. FTIR and TG/DTA studies revealed that powders existed as In(OH)3H2O—SnO3H2H2O in the solid state and then they transformed to In2O3—SnO2 via some metastable intermediates after 300°C. Cubic phase of In2O3 was identified by XRD for the oxides up to 30% of Sn. Particle size measurements of the solid dispersed in acetone and SEM
study for microstructure showed that the oxides were in the nano range (55-75 nm) whereas the size range determined from Debye-Scherrer
equation were 11–24 nm. 相似文献
2.
Organic‐acid‐catalyzed sol–gel route for preparing poly(methyl methacrylate)–silica hybrid materials
Jui‐Ming Yeh Kuan‐Yeh Huang Chung‐Feng Dai B. G. Chand Chang‐Jian Weng 《应用聚合物科学杂志》2008,110(4):2108-2114
In this study, a series of organic–inorganic hybrid sol–gel materials consisting of a poly(methyl methacrylate) (PMMA) matrix and dispersed silica (SiO2) particles were successfully prepared through an organic‐acid‐catalyzed sol–gel route with N‐methyl‐2‐pyrrolidone as the mixing solvent. The as‐synthesized PMMA–SiO2 nanocomposites were subsequently characterized with Fourier transform infrared spectroscopy and transmission electron microscopy. The solid phase of organic camphor sulfonic acid was employed to catalyze the hydrolysis and condensation (i.e., sol–gel reactions) of tetraethyl orthosilicate in the PMMA matrix. The formation of the hybrid membranes was beneficial for the physical properties at low SiO2 loadings, especially for enhanced mechanical strength and gas barrier properties, in comparison with the neat PMMA. The effects of material composition on the thermal stability, thermal conductivity, mechanical strength, molecular permeability, optical clarity, and surface morphology of the as‐prepared hybrid PMMA–SiO2 nanocomposites in the form of membranes were investigated with thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, gas permeability analysis, ultraviolet–visible transmission spectroscopy, and atomic force microscopy, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
3.
Nipin KohliAuthor VitaeOnkar SinghAuthor Vitae Ravi Chand SinghAuthor Vitae 《Sensors and actuators. B, Chemical》2011,158(1):259-264
Nanoparticles of chromium oxide have been synthesized by following a co-precipitation route at various pH values of the precursor solution. Structural and morphological analysis were carried out by using XRD and TEM techniques which revealed that the size of nanoparticles synthesized at pH 9 was smaller as compared to those synthesized at other pH values. The thick films of synthesized samples were deposited on alumina substrate and their sensing response to methanol, ethanol and isopropanol was investigated at different operating temperatures. It was observed that all the sensors gave optimum response at 250 °C. It has been observed that sample prepared at pH 9, being a collection of smallest particles as compared to other samples, exhibited high sensing response to alcohol vapour. Sensor response of all the samples tested was significantly higher towards isopropanol vapour than towards methanol or ethanol.In the present study the effect of particle size on intergranular activation energy has been studied as well. It was found that smaller particles possess high activation energy and exhibit higher sensing response as compared to that of larger particles. This type of study may help in the selection of particle suitable for gas sensing. 相似文献
4.
Harish Sharma Jagdish Chand Bansal K. V. Arya Xin-She Yang 《International journal of systems science》2016,47(11):2652-2670
Artificial bee colony (ABC) optimisation algorithm is a relatively simple and recent population-based probabilistic approach for global optimisation. The solution search equation of ABC is significantly influenced by a random quantity which helps in exploration at the cost of exploitation of the search space. In the ABC, there is a high chance to skip the true solution due to its large step sizes. In order to balance between diversity and convergence in the ABC, a Lévy flight inspired search strategy is proposed and integrated with ABC. The proposed strategy is named as Lévy Flight ABC (LFABC) has both the local and global search capability simultaneously and can be achieved by tuning the Lévy flight parameters and thus automatically tuning the step sizes. In the LFABC, new solutions are generated around the best solution and it helps to enhance the exploitation capability of ABC. Furthermore, to improve the exploration capability, the numbers of scout bees are increased. The experiments on 20 test problems of different complexities and five real-world engineering optimisation problems show that the proposed strategy outperforms the basic ABC and recent variants of ABC, namely, Gbest-guided ABC, best-so-far ABC and modified ABC in most of the experiments. 相似文献
5.
Consider the robust network design problem of finding a minimum cost network with enough capacity to route all traffic demand
matrices in a given polytope. We investigate the impact of different routing models in this robust setting: in particular,
we compare oblivious routing, where the routing between each terminal pair must be fixed in advance, to dynamic routing, where routings may depend arbitrarily on the current demand. Our main result is a construction that shows that the
optimal cost of such a network based on oblivious routing (fractional or integral) may be a factor of Ω(log n) more than the cost required when using dynamic routing. This is true even in the important special case of the asymmetric
hose model. This answers a question in (Chekuri, SIGACT News 38(3):106–128, 2007), and is tight up to constant factors. Our proof technique builds on a connection between expander graphs and robust design
for single-sink traffic patterns (Chekuri et al., Networks 50(1):50–54, 2007). 相似文献
6.
Apoorva G. Wagh Veer Chand Rakhecha Makus Strobl Wolfgang Treimer 《Journal of research of the National Institute of Standards and Technology》2005,110(3):231-235
Super Ultra-Small Angle Neutron Scattering (SUSANS) studies over wave vector transfers of 10–4 nm–1 to 10–3 nm–1 afford information on micrometer-size agglomerates in samples. Using a right-angled magnetic air prism, we have achieved a separation of ≈10 arcsec between ≈2 arcsec wide up- and down-spin peaks of 0.54 nm neutrons. The SUSANS instrument has thus been equipped with the polarized neutron option. The samples are placed in a uniform vertical field of 8.8 × 104 A/m (1.1 kOe). Several magnetic alloy ribbon samples broaden the up-spin neutron peak significantly over the ±1.3 × 10–3 nm–1 range, while leaving the down-spin peak essentially unaltered. Fourier transforms of these SUSANS spectra corrected for the instrument resolution, yield micrometer-range pair distribution functions for up- and down-spin neutrons as well as the nuclear and magnetic scattering length density distributions in the samples. 相似文献
7.
Michel Cosnard Luigi Liquori Raphael Chand 《Electronic Notes in Theoretical Computer Science》2007,171(3):55
Arigatoni is a lightweight overlay network that deploys the Global Computing Paradigm over the Internet. Communication for over the behavioral units of the overlay is performed by a simple resource discovery protocol (RDP). Basic Global Computers Units (GC) can communicate by first registering to a brokering service and then by mutually asking and offering services.Colonies and communities are the main entities in the model. A colony is a simple virtual organization composed by exactly one leader and some set (possibly empty) of individuals. A community is a raw set of colonies and global computers (think it as a soup of colonies and global computer without a leader).We present an operational semantics via a labeled transition system, that describes the main operations necessary in the Arigatoni model to perform leader negotiation, joining/leaving a colony, linking two colonies and moving one GC from one colony to another. Our formalization results to be adequate w.r.t. the algorithm performing peer logging/delogging and colony aggregation. 相似文献
8.
Rastogi NK 《Critical reviews in food science and nutrition》2011,51(8):705-722
The demand for convenience foods of the highest quality in terms of natural flavor and taste, and which are free from additives and preservatives, has spurred the need for the development of a number of non-thermal approaches to food processing, of which ultrasound technology has proven to be very valuable. Increasing number of recent publications have demonstrated the potential of this technology in food processing. A combination of ultrasound with pressure and/or heat is a promising alternative for the rapid inactivation of microorganisms and enzymes. Therefore, novel techniques like thermosonication, manosonication, and manothermosonication may be a more relevant energy-efficient processing alternative for the food industry in times to come. This review aims at identifying the opportunities and challenges associated with this technology. In addition to discussing the effects of ultrasound on foods, this review covers various areas that have been identified as having great potential for future development. It has been realized that ultrasound has much to offer to the food industry such as inactivation of microorganisms and enzymes, crystallization, drying, degassing, extraction, filtration, homogenization, meat tenderization, oxidation, sterilization, etc., including efficiency enhancement of various operations and online detection of contaminants in foods. Selected practical examples in the food industry have been presented and discussed. A brief account of the challenges in adopting this technology for industrial development has also been included. 相似文献
9.
A surface functionalized gas sensing material convincingly giving enhanced response to ethanol is demonstrated by SnO2 activated ZnO. Zinc oxide was synthesized by a chemical route, deposited on an alumina substrate and activated by tin dioxide obtained by on-site oxidation of tin chloride. The XRD study of samples confirmed wurtzite hexagonal structure of zinc oxide and FESEM investigation revealed that surface of activated ZnO microrods was covered by nanoparticles of tin dioxide. Sensing response of sensing elements activated with different concentrations of tin chloride solution has been investigated. It was found that response to ethanol vapor significantly enhanced (eight times) by surface activation with tin dioxide, which optimized at a concentration of 3 wt.%. 相似文献
10.
Khetan Shevkani Narpinder Singh Jai Chand Rana Amritpal Kaur 《International Journal of Food Science & Technology》2014,49(2):541-550
Protein isolates from six amaranth lines/cultivars (APIs) were evaluated to study their physicochemical (hunter colour, protein content and zeta potential), structural (thermal and conformational) and functional (emulsification, foaming, water and fat absorption) properties. APIs had protein content, whiteness index and gel temperature in range of 79.4–85.4%, 41.17–54.26 and 87.8–91.8 °C, respectively. The Fourier‐transform infrared spectra of APIs revealed α‐helix, β‐sheets and random coil conformations in the secondary structure. APIs with higher relative proportion of β‐sheets had higher Differential Scanning Calorimeter denaturation temperature and gel temperature. Minimum protein solubility (PS) was observed at pH 5.0, indicating isoelectric point (pI) of amaranth proteins. The PS, emulsifying activity index (EAI), emulsifying stability index (ESI), foaming capacity (FC) and foam stability (FS) of APIs at neutral pH were related to their zeta potential (ζ). The emulsifying and foaming properties were also determined at different pHs (between 2.0 and 9.0). The EAI‐pH profile of APIs confirmed close relationship between the emulsifying ability and PS. 相似文献