全文获取类型
收费全文 | 464篇 |
免费 | 16篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 10篇 |
综合类 | 1篇 |
化学工业 | 47篇 |
金属工艺 | 3篇 |
机械仪表 | 5篇 |
建筑科学 | 15篇 |
能源动力 | 15篇 |
轻工业 | 54篇 |
水利工程 | 4篇 |
石油天然气 | 3篇 |
无线电 | 28篇 |
一般工业技术 | 115篇 |
冶金工业 | 145篇 |
原子能技术 | 6篇 |
自动化技术 | 30篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 5篇 |
2017年 | 12篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 9篇 |
2013年 | 14篇 |
2012年 | 17篇 |
2011年 | 25篇 |
2010年 | 26篇 |
2009年 | 17篇 |
2008年 | 29篇 |
2007年 | 17篇 |
2006年 | 22篇 |
2005年 | 10篇 |
2004年 | 18篇 |
2003年 | 3篇 |
2002年 | 7篇 |
2001年 | 11篇 |
2000年 | 11篇 |
1999年 | 9篇 |
1998年 | 38篇 |
1997年 | 28篇 |
1996年 | 20篇 |
1995年 | 13篇 |
1994年 | 21篇 |
1993年 | 15篇 |
1992年 | 8篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 12篇 |
1975年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有481条查询结果,搜索用时 15 毫秒
101.
J.M. Khoshman N. PeicaC. Thomsen J. MaultzschB. Bastek C. WanM.E. Kordesch 《Thin solid films》2012,520(24):7230-7235
Zinc nitride films were deposited on Si(100) substrates at room temperature using RF-magnetron sputtering in pure N2 and in Ar + N2 atmospheres. Two active phonon modes (270.81 and 569.80 cm− 1) are observed in Raman spectra for films deposited in Ar + N2 atmosphere. Atomic force microscopy showed that the average surface roughness of the films deposited in pure N2 atmosphere (1.3-3.33 nm) was less than for those deposited in a mixed Ar + N2 atmosphere (10.3-12.8 nm). Low temperature cathodoluminescence showed two emission bands centered at 2.05 eV and 3.32 eV for both types of films. 相似文献
102.
K Alvåsen M Jansson Mörk C Hallén Sandgren PT Thomsen U Emanuelson 《Journal of dairy science》2012,95(8):4352-4362
An increase in on-farm mortality (euthanasia and death) in dairy herds has been reported in several countries in the last decade. This does not only imply possible problems with animal welfare, but it also causes economic losses to the farmer. The objective of this study was to evaluate time trends in on-farm dairy cow mortality in Sweden and identify potential herd-level risk factors. Data were retrieved on all Swedish dairy herds enrolled in the milk recording scheme between 2002 and 2010. Herds with a herd size of <20 cows or a mortality rate (MR) of >40 dead or euthanized cows per 100 cow-years were excluded. Two different models were used: 1 multiple-year analysis, which included 6,898 herds during the period 2002 to 2010 and 1 single-year analysis including 4,252 herds for the year 2010, where other variables that were not present during the entire multiple year study were analyzed. The outcome variable was the number of euthanized and dead cows per year and season. A negative binomial regression model, adjusted for clustering within herd, was applied to both models. Fixed effects in the multiple-year analysis were breed, calving interval, herd size, milk yield, region, season, pasture period, and year. The fixed effects in the single-year analysis were breed, calving interval, conventional versus organic farming, herd size, housing system, milk yield, region, and season. The results demonstrated that MR gradually increased from 5.1 to 6.6 events per 100 cow-years during the study period. Swedish MR are consequently on par with, or even greater than, MR among dairy herds in other comparable countries. Higher mortality was associated with larger herd size, longer calving intervals, and herds that had Swedish Holstein as the predominant breed. Lower mortality was observed in herds with a higher herd average milk yield, during the fall and winter, and in organically managed herds. There were regional differences in mortality. An interaction between herd size and season was found in both models. Also, an interaction between housing system and milk yield was found in the single-year analysis. This first assessment of on-farm mortality in Swedish dairy herds confirmed that the MR has increased over the last few years. The study also identified some herd-level risk factors. 相似文献
103.
L. Zanini S. Dementjev W. Leung K. Thomsen M. Wohlmuther A. Class P. Agostini J.-C. David S. Leray L. Cachon P. Roubin N. Thiolliere 《Journal of Nuclear Materials》2011,415(3):367-377
The (MEGAWatt Pilot Experiment) MEGAPIE target was successfully irradiated in 2006 at the SINQ facility of the Paul Scherrer Institut. During the irradiation a series of measurements to monitor the operation of the target, the thermal hydraulics behavior and the neutronic and nuclear aspects, has been performed. In the post-test analysis phase of the project, the data were analyzed and important information relevant to accelerator-driven systems (ADS) was gained, in particular: (i) from the operation of the target several recommendations concern the simplification of the system and the improved reliability; (ii) data from the thermal hydraulic measurements have offered the opportunity to validate the codes used in the design phase; (iii) the neutronic analysis confirm the high performance of a liquid metal target and the importance of the delayed neutron measurements in an ADS target; (iv) the nuclear measurements of the gas released gave the opportunity to validate the codes used during the design phase and provided indications for the operation. From the results in these different domains recommendations to further development of ADS and heavy liquid metal targets are discussed. 相似文献
104.
Here, we show that the Raman intensity of the G-mode in tip-enhanced Raman spectroscopy (TERS) is strongly dependent on the
height of the bundle. Moreover, using TERS we are able to position different single-walled carbon nanotubes along a bundle,
by correlating the observed radial breathing mode (RBM) with the AFM topography at the measuring point. The frequency of the
G- mode behaves differently in TERS as compared to far-field Raman. Using the RBM frequency, the diameters of the tubes were
calculated and a very good agreement with the G- -mode frequency was observed. 相似文献
105.
Werner Wagner Friedrich Gröschel Knud Thomsen Hajo Heyck 《Journal of Nuclear Materials》2008,377(1):12-16
The lead-bismuth liquid metal target MEGAPIE (MEGAwatt Pilot Experiment) was operated at the Swiss Spallation Neutron Source SINQ starting mid-August 2006, for a scheduled irradiation period until 21st of December 2006. The continuous (51 MHz) 590 MeV proton beam hitting the target reaches routinely an average current of ∼1300 μA, corresponding to a beam power 0.77 MW. This article illustrates the main features of the target and the ancillary systems specially needed for the liquid metal target operation. Further, the operational experiences made with this target during start-up and routine operation are summarized, besides the general performance highlighting new beam and target safety devices, and last but not least the neutronic efficiency in relation to the previously operated solid lead target. 相似文献
106.
Fox J. Marsack J. Kim J. Thomsen S. Rylander H.G. III Milner T.E. 《IEEE journal of selected topics in quantum electronics》2001,7(6):899-905
We report results of a study using optical coherence tomography (OCT) to create area maps of the retinal nerve fiber layer (RNFL) thickness. Low-resolution B scans (two-dimensional images) of the in vivo rhesus monkey retina have been recorded in the optic disk, peripapillary area, and macula. Three-dimensional (3-D) renderings of these areas have been created from OCT images and compared to corresponding data from histology. Results of our study indicate: (1) OCT may be utilized to measure the retinal nerve fiber layer thickness in vivo and (2) 3-D surface maps accurately depict the anatomy of the RNFL 相似文献
107.
Compas Bruce E.; Connor-Smith Jennifer K.; Saltzman Heidi; Thomsen Alexandria Harding; Wadsworth Martha E. 《Canadian Metallurgical Quarterly》2001,127(1):87
Progress and issues in the study of coping with stress during childhood and adolescence are reviewed. Definitions of coping are considered, and the relationship between coping and other aspects of responses to stress (e.g., temperament and stress reactivity) is described. Questionnaire, interview, and observation measures of child and adolescent coping are evaluated with regard to reliability and validity. Studies of the association of coping with symptoms of psychopathology and social and academic competence are reviewed. Initial progress has been made in the conceptualization and measurement of coping, and substantial evidence has accumulated on the association between coping and adjustment. Problems still remain in the conceptualization and measurement of coping in young people, however, and aspects of the development and correlates of coping remain to be identified. An agenda for future research on child–adolescent coping is outlined. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
108.
Interet telephony is possibly the fastest-growing part of communications today. This article discusses what exactly it is, who needs it, and how it works. Internet telephony, or voice over Internet protocol (VoIP), is the provision of phone service over the Internet. But in sharp contrast with conventional telephony, it carries voice traffic as data packets over a packet-switched data network instead of as a synchronous stream of binary data over a circuit-switched, time-division multiplexed (TDM) voice network. There are some substantial benefits (as well as some sticky problems) to the scheme, which is why companies and individuals are finding it increasingly attractive 相似文献
109.
The paper concerns local effects occurring in the vicinity of junctions between different cores in sandwich beams subjected to tensile in-plane loading. It is known from analytical and numerical modelling that these effects display themselves by an increase of the bending stresses in the faces as well as the core shear and transverse normal stresses at the junction. The local effects have been studied experimentally to assess the influence on the failure behaviour both under quasi-static and fatigue loading conditions. Typical sandwich beam configurations with aluminium and glass-fibre reinforced plastic (GFRP) face sheets and core junctions between polymer foams of different densities and rigid plywood or aluminium were investigated. Depending on the material configuration of the sandwich beam, premature failure accumulating at the core junction was observed for quasi-static and/or fatigue loading conditions. Using Aluminium face sheets, quasi-static loading caused failure at the core junction, whereas no significance of the junction was observed for fatigue loading. Using GFRP faces, a shift of the failure mode from premature core failure in quasi-static tests to face failure at the core junction in fatigue tests was observed. In addition to the failure tests, the sandwich configurations have been analysed using finite element modelling (FEM) to elaborate on the experimental results with respect to failure prediction. Both linear modelling and nonlinear modelling including nonlinear material behaviour (plasticity) was used. Comparing the results from finite element modelling with the failure behaviour observed in the quasi-static tests, it was found that a combination of linear finite element modelling and a point stress criterion to evaluate the stresses at the core junction can be used for brittle core material constituents. However, this is generally not sufficient to predict the failure modes and failure loads properly. Using nonlinear material properties in the modelling and a point strain criterion improves the failure prediction especially for ductile materials, but this has to be examined further along with other failure criteria. 相似文献
110.