全文获取类型
收费全文 | 763篇 |
免费 | 40篇 |
专业分类
电工技术 | 14篇 |
综合类 | 6篇 |
化学工业 | 252篇 |
金属工艺 | 6篇 |
机械仪表 | 40篇 |
建筑科学 | 21篇 |
能源动力 | 23篇 |
轻工业 | 90篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 33篇 |
一般工业技术 | 96篇 |
冶金工业 | 23篇 |
原子能技术 | 11篇 |
自动化技术 | 182篇 |
出版年
2024年 | 1篇 |
2023年 | 10篇 |
2022年 | 58篇 |
2021年 | 59篇 |
2020年 | 25篇 |
2019年 | 26篇 |
2018年 | 21篇 |
2017年 | 24篇 |
2016年 | 37篇 |
2015年 | 17篇 |
2014年 | 31篇 |
2013年 | 57篇 |
2012年 | 59篇 |
2011年 | 47篇 |
2010年 | 40篇 |
2009年 | 32篇 |
2008年 | 30篇 |
2007年 | 29篇 |
2006年 | 23篇 |
2005年 | 27篇 |
2004年 | 14篇 |
2003年 | 22篇 |
2002年 | 21篇 |
2001年 | 8篇 |
2000年 | 9篇 |
1999年 | 11篇 |
1998年 | 4篇 |
1997年 | 17篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1975年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有803条查询结果,搜索用时 15 毫秒
61.
Reliability as Tool for Hydraulic Network Planning 总被引:1,自引:0,他引:1
This paper presents a methodology to evaluate the reliability of water distribution systems that can be used in the design phase and for identifying repair works to be carried out on existing systems. The methodology is based on the statistical analysis of dimensionless performance indices (hydraulic performance indices) derived from a large number of simulations of various water system demand scenarios and∕or operating conditions. The hydraulic reliability index is assumed as the probability that, under a given operating condition, the hydraulic performance index will be above a certain threshold. Finally, the system's overall reliability (mechanical + hydraulic) is estimated using the overall reliability index, which is defined by the weighted mean of the hydraulic performance indices obtained for the various operating conditions. A case study using this methodology shows the concrete possibilities of applying this approach to a wide spectrum of cases, and the small influence on overall system reliability normally exerted by such events as the failure of links, pipes, and valves. 相似文献
62.
A neural approach to modeling measurement devices is presented. This approach allows the usual components of a measurement apparatus (transducers, filters, amplifiers, analog-to-digital converters, etc.) to be easily modeled by means of suitably trained artificial neural networks. Two applications regarding analog and mixed analog/digital devices are reported, highlighting the peculiarity of this approach and the accuracy that can be obtained. 相似文献
63.
Domenico Baú Massimiliano Ferronato Giuseppe Gambolati Pietro Teatini 《Canadian Metallurgical Quarterly》2001,1(4):459-475
The land subsidence spreading factor χ provides a useful straightforward indication on how much of a gas/oil reservoir compaction induced by field development migrates to ground surface with a possible adverse impact on the stability of low‐lying coastal areas. This factor depends primarily on the ratio between the depth of burial and a representative horizontal dimension of the reservoir. However, an important influence is also exerted by the active bottom/lateral aquifer hydraulically connected to the field (called “waterdrive” in reservoir engineering) that may undergo an extensive depressurization also after the field abandonment, thus contributing to enhance the overall land settlement. In the Northern Adriatic basin, Italy, χ is evaluated using a nonlinear finite element model of three representative gas reservoirs (Chioggia Mare, Dorotea, and Dosso degli Angeli) surrounded by important bottom/lateral aquifers in the interval depth between 1000 and 3300 m. Results show that χ may easily approach and even exceed one for the deepest field as well, contrary to the prediction of land subsidence based on the compaction of the gas‐bearing formations alone, that can thus be largely underestimated. 相似文献
64.
Abstract. In this article we consider polynomial cointegrating relationships between stationary processes with long range dependence. We express the regression functions in terms of Hermite polynomials and consider a form of spectral regression around frequency zero. For these estimates, we establish consistency by means of a more general result on continuously averaged estimates of the spectral density matrix at frequency zero. 相似文献
65.
Pietro Calandra Domenico Lombardo Angela Ruggirello Vincenzo Turco Liveri 《Materials Letters》2010,64(5):576-181
Surfactant-coated ytterbium nanoparticles were produced by Nd:YAG laser ablation of a Yb bulk target immersed in sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/n-heptane micellar solution. In our experimental conditions, as highlighted by IR spectroscopy, AOT molecules are not decomposed by the intense laser pulses but play a pivotal role in the stabilisation of Yb nanoparticles. The formation of Yb nanoparticles in the liquid phase was monitored by UV-Vis spectroscopy whereas the Yb/AOT composites obtained by evaporation of the organic solvent were characterised by XPS and TEM. Data analysis consistently shows the presence of surfactant-coated, nearly spherical and non-interacting Yb nanoparticles of mean diameter of 3 nm.Moreover, the presence of bigger polycrystalline nanoparticles (about 30%) in coexistence with smaller mono crystalline ones indicates that, after the rapid formation of the pristine Yb nanoparticles from plume condensation, two processes effectively compete for their size distribution: nanoparticle agglomeration and surfactant adsorption. 相似文献
66.
Marco Giovambattista Luigi Andrea Domenico Vasile 《Computer Languages, Systems and Structures》2000,26(2-4)
In this paper a logic-based specification language, called
-
, is presented. The language is obtained by extending
through allowing a limited use of some second-order predicates of predefined form.
-
programs specify solutions to problems in a very abstract and concise way, and are executable. In the present prototype they are compiled to
code, which is run to construct outputs. Second-order predicates of suitable form allow to limit the size of search spaces in order to obtain reasonably efficient construction of problem solutions.
-
expressive power is precisely characterized as to express exactly the problems in the class NP. The specification of several combinatorial problems in
-
is shown, and the efficiency of the generated programs is evaluated. 相似文献
67.
Domenico Campolo 《Mechatronics》2010,20(5):566-573
This paper presents a novel method for selecting the most appropriate motor–gearhead combination for nonlinearly damped, resonant loads. The method extends to the nonlinear damping case the impedance-matching condition which is used to guarantee a maximum power transfer in linear network theory. In particular, the method is applicable in general to resonant loads where the damping is an odd and memoryless nonlinear function of the velocity. This condition is very common in biomimetic robotics, in particular when designing propulsion systems based on flapping appendages, such as wings or fins, in viscous fluids, such as air or water. The method is graphical in nature and is based on a power vs. impedance-mismatch factor. Such a factor is function of the ratio of the motor armature resistance to the load equivalent resistive impedance reflected at the motor armature, where the latter is nonlinear and depends on the desired kinematics as well as on the transmission ratio and efficiency. The method allows comparing, for a given desired appendage kinematics, all motor–gearhead combinations at once while taking into account all possible constraints such as maximum current, power, and torque. 相似文献
68.
Mercanti DJ Carminati D Reinheimer JA Quiberoni A 《International journal of food microbiology》2011,144(3):503-510
Prophages account for most of the genetic diversity among strains of a given bacterial species, and represent a latent source for the generation of virulent phages. In this work, a set of 30 commercial, collection and dairy-isolated Lactobacillus casei group strains were used. A species-specific PCR assay allowed a reclassification, mainly of strains previously considered Lactobacillus casei, into either Lactobacillus paracasei or Lactobacillus rhamnosus. All the strains were induced with mitomycin C, allowing direct recovering of phage DNA in 25 cases, which corroborates the widely occurrence of lysogeny on Lactobacillus genomes, including probiotic strains of Lactobacillus casei group. Ten out of 11 commercial strains studied contained prophages, evidencing the potential risks of their use at industrial scale. Strains were also induced by treatment with different concentrations of hydrogen peroxide but, however, this agent was not able to evidence a prophage release for any of the strains tested. According to a RAPD-PCR fingerprinting with M13, 1254 and G1 primers, most of the commercial strains presented a high degree of homology and, regarding BglII- and BamHI-restriction profiles of phage DNA, six of them harboured the same prophage. Surprisingly, both Lactobacillus paracasei ATCC 27092 and Lactobacillus paracasei ATCC 27139 shared a second prophage with both an INLAIN collection and a commercial Lactobacillus paracasei strains, whereas two collection strains shared a third one. On the other hand, mitomycin C-inducible prophages were detected only on about a half of the strains isolated from dairy products, which had (with only one exception) from moderate to high correlation coefficients according to RAPD-PCR fingerprinting. After induction, supernatants were filtered and tested against nine Lactobacillus strains of the set sensitive to previously assayed virulent phages, allowing isolation of two new virulent phages: ф iLp1308 and ф iLp84. Both phages were able to lyse all but one strains sensitive to previously assayed phage MLC-A. 相似文献
69.
70.