全文获取类型
收费全文 | 181篇 |
免费 | 3篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 50篇 |
金属工艺 | 6篇 |
机械仪表 | 1篇 |
建筑科学 | 4篇 |
能源动力 | 4篇 |
轻工业 | 25篇 |
水利工程 | 1篇 |
无线电 | 20篇 |
一般工业技术 | 19篇 |
冶金工业 | 10篇 |
原子能技术 | 7篇 |
自动化技术 | 34篇 |
出版年
2021年 | 1篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2013年 | 16篇 |
2012年 | 7篇 |
2011年 | 16篇 |
2010年 | 10篇 |
2009年 | 19篇 |
2008年 | 4篇 |
2007年 | 9篇 |
2006年 | 9篇 |
2005年 | 8篇 |
2004年 | 8篇 |
2003年 | 8篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1972年 | 2篇 |
1968年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有185条查询结果,搜索用时 671 毫秒
11.
Helmi Keskinen Jyrki M. Mäkelä Mikko Aromaa Jorma Keskinen Sami Areva Cilâine V. Teixeira Jarl B. Rosenholm Viljami Pore Mikko Ritala Markku Leskelä Mari Raulio Mirja S. Salkinoja-Salonen Erkki Levänen Tapio Mäntylä 《Catalysis Letters》2006,111(3-4):127-132
Titania and titania-silver nanoparticle deposits were made by Liquid Flame Spray technique, in which the liquid precursor
is injected into a high temperature flame, where it will evaporate and nucleate to nanosize particles. One-step and two-step
methods were used for preparation of titania-silver deposits. The amount of silver added was 1 wt%. The deposits were collected
in the flame zone on steel and glass surfaces and were analyzed by TEM, EDS, XPS and SAXS. The titania deposits consisted
of porous nanosized titania agglomerates of primary particles (~10 nm). With silver addition, small spherical silver metal
particles (~2 nm) were detected on the agglomerates. An increase in the photocatalytic activity was verified by stearic acid
decomposition and biofilm removal using Deinococcus geothermalis as the model organism. 相似文献
12.
Functional reliability of a service firearm is essential. A failure to fire at a critical moment could lead to disastrous consequences. The firing pin of a weapon must hit the primer hard enough to ascertain reliable detonation of the primer which then ignites the powder. Depths of firing pin created indent on an inert primer and on a copper cylinder are the two methods conventionally used to estimate this percussion energy. In this study the copper cylinder method was compared with piezoelectric measurement. It was found out that both systems give reliable readings. Eight pistols of calibre 9 mm were measured. Although the majority of the measured weapons seemed to provide sufficient percussion energy, there were some surprisingly low readings with seemingly perfect weapons. This discrepancy shows the necessity of an industrial standard and of using a reliable percussion energy measurement system for monitoring the condition of service weapons. Further research on firearm and ammunition primer compatibility is required. 相似文献
13.
We present a Boyer–Moore (BM) approach to string matching over LZ78 and LZW compressed text. The idea is to search the text directly in compressed form instead of decompressing and then searching it. We modify the BM approach so as to skip text using the characters explicitly represented in the LZ78/LZW formats, modifying the basic technique where the algorithm can choose which characters to inspect. We present and compare several solutions for single and multipattern searches. We show that our algorithms obtain speedups of up to 50% compared to the simple decompress‐then‐search approach. Finally, we present a public tool, LZgrep, which uses our algorithms to offer grep‐like capabilities directly searching files compressed using Unix's Compress, a LZW compressor. LZgrep can also search files compressed with Unix gzip, using new decompress‐then‐search techniques we develop, which are faster than the current tools. This way, users can always keep their files in compressed form and still search them, uncompressing only when they want to see them. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
14.
Karvinen J Laitala V Mäkinen ML Mulari O Tamminen J Hermonen J Hurskainen P Hemmilä I 《Analytical chemistry》2004,76(5):1429-1436
We have developed assay technologies to measure hydrolyzing enzymes based on homogeneous time-resolved fluorescence quenching (TruPoint). High sensitivity was obtained using fluorescent europium chelates as labels, internally quenched by suitable quenchers and released upon enzymatic reaction. This approach allows robust and sensitive monitoring of low enzyme activities. The assay technology and the choice of donor-acceptor pairs were evaluated in three different enzymatic assays, a protease related to apoptosis, helicase involved in DNA unwinding, and phosphatase having an important role in cellular signaling cascades. All the assays produced an increasing signal, were sensitive, and had a good dynamic range. There were significant differences in optimized quenchers for each of the assays depending on the size, flexibility, and rigidity of the substrates. Also, clear differences in the energy-transfer reactions, their requirements for spectral overlapping, ionic interactions, and energy-transfer distances were found. Each of the enzymatic assays was briefly tested in a high-throughput screening environment by analyzing signal dynamics and statistical relevance as Z' factors. 相似文献
15.
Random waypoint mobility model in cellular networks 总被引:2,自引:0,他引:2
In this paper we study the so-called random waypoint (RWP) mobility model in the context of cellular networks. In the RWP model the nodes, i.e., mobile users, move along a zigzag path consisting of straight legs from one waypoint to the next. Each waypoint is assumed to be drawn from the uniform distribution over the given convex domain. In this paper we characterise the key performance measures, mean handover rate and mean sojourn time from the point of view of an arbitrary cell, as well as the mean handover rate in the network. To this end, we present an exact analytical formula for the mean arrival rate across an arbitrary curve. This result together with the pdf of the node location, allows us to compute all other interesting measures. The results are illustrated by several numerical examples. For instance, as a straightforward application of these results one can easily adjust the model parameters in a simulation so that the scenario matches well with, e.g., the measured sojourn times in a cell. 相似文献
16.
The first part of this article reports the analytical form of the Electrical Low Pressure Impactor (ELPI) kernel functions. In this latter part, the numerical quality of ELPI response matrices is studied and an example of an inversion algorithm is given. The ELPI assemblies with and without an electrical filter stage and with smooth or sintered impaction plates are studied and compared with basic impactor kernels and the kernels for the calculation of the aerosol mass distribution. It is shown that the ELPI assembly with the electrical filter stage and smooth impaction plates should be the best choice for the inversion of data if no bounce occurs. The comparison to a mass impactor shows that the devices are on par in data inversion. The inversion ELPI data is studied with a Bayesian algorithm assuming a bimodal lognormal size distribution of the aerosol. The algorithm includes a novel procedure for obtaining an initial guess of the distribution parameters. To our knowledge, it is also the first algorithm to use ELPI current readings as its input. Simulations and diesel emission measurements show that the proposed algorithm is a useful tool in the study of ELPI data. 相似文献
17.
18.
Helmi Keskinen Sami Romakkaniemi Antti Jaatinen Pasi Miettinen Erkka Saukko Joutsensaari Jorma 《Aerosol science and technology》2013,47(12):1441-1447
The first wetting layer on solid nanoparticles has direct implications on the roles these particles play in industrial processes and technological applications as well as in the atmosphere. We present a technique for online measurements of the adsorption of the first few water layers onto insoluble aerosol nanoparticles. Atomized fumed silica nanoparticles were dispersed from aqueous suspension and their hygroscopic growth factors (HGF) and number of the adsorbed water layers at subsaturated conditions were measured using a nanometer hygroscopic tandem differential mobility analyzer (HTDMA). Particle morphology was characterized by electron microscopy and particle density was determined by mobility analysis. The HGFs of the size-selected particles at mobility diameters from 10 to 50 nm at 90% relative humidity (RH) varied from 1.05 to 1.24, corresponding to 2–6 layers of adsorbed water. The morphology of the generated fumed silica nanoparticles varied from spheres at 8–10 nm to agglomerates at larger diameters with effective density from 1.7 to 0.8 g/cm3 and fractal dimension of 2.6. The smallest spheres and agglomerates had the highest HGFs. The smallest particles with diameters of 8 and 10 nm adsorbed two to three water layers in subsaturated conditions, which agreed well with the Frenkel, Halsey, and Hill (FHH) isotherm fitting. In comparison to the small spheres or large agglomerates, the compact agglomerate structure containing a few primary particles increased the number of adsorbed water layers by a factor of ~1.5. This was probably caused by the capillary effect on the small cavities between the primary particles in the agglomerate. 相似文献
19.
Albert G. Nasibulin Olivier Richard Esko I. Kauppinen David P. Brown Jorma K. Jokiniemi Igor S. Altman 《Aerosol science and technology》2013,47(8):899-911
Crystalline nanometer-sized Cu 2 O and CuO particle formation was studied by vapor thermal decomposition of copper (II) acetylacetonate in a vertical laminar flow reactor at ambient pressure. Experiments were carried out at 3 furnace temperature profiles (maximum values of t furn = 432, 596, 705°C) and with 2 carrier gases (oxygen/nitrogen with mixture ratios of 0.5/99.5 and 10.0/90.0). The results of computational fluid dynamics simulations are presented. The introduction of oxygen into the system was found to increase the decomposition rate and removed impurities from particles. The size of produced primary particles varied from 10 to 200 nm. Particle crystallinity was found to depend on both the oxygen concentration and the furnace temperature. A model taking into account the detailed chemical reaction mechanisms during the particle formation is proposed. The model allows one to build a dynamic phase diagram of the condensed products formed during the decomposition and is in good agreement with the experimental results. 相似文献
20.
The first third-generation (3G) systems are going to be implemented within the year 2001. Academia and industry are, however, already looking for means to improve the system performance further. Spectral efficiency and higher data rate are the goal. In order to achieve this goal, several means have to be combined. The most important of these are interference cancellation and multiuser detection, optimum space-time processing and adaptive modulation and coding. In the future several wireless systems having different performance characteristics, system structure and parameters will exist. This heterogeneity will make the seamless handover from system to system difficult if not appropriately solved. 4G (fourth generation) is an acronym without any generally accepted concept. We describe some desirable goals and features of the 4G systems. 相似文献