全文获取类型
收费全文 | 226篇 |
免费 | 16篇 |
学科分类
工业技术 | 242篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 9篇 |
2020年 | 12篇 |
2019年 | 8篇 |
2018年 | 9篇 |
2017年 | 5篇 |
2016年 | 9篇 |
2015年 | 8篇 |
2014年 | 11篇 |
2013年 | 19篇 |
2012年 | 13篇 |
2011年 | 25篇 |
2010年 | 17篇 |
2009年 | 10篇 |
2008年 | 9篇 |
2007年 | 16篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 10篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1991年 | 2篇 |
1989年 | 4篇 |
1987年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有242条查询结果,搜索用时 15 毫秒
71.
72.
73.
Modeling Lac du Bonnet granite using a discrete element model 总被引:6,自引:0,他引:6
Yuannian Wang Fulvio Tonon 《International Journal of Rock Mechanics and Mining Sciences》2009,46(7):1124-1135
A discrete element method code developed by the authors is used to model Lac du Bonnet granite in triaxial compression. The paper first presents the features of the model and the algorithms used to identify the micro deformability and strength parameters. With these identification algorithms, the model was calibrated to match experimental triaxial test data on Lac du Bonnet granite. With the calibrated model, investigation on failure evolution was then performed. The monitored evolution of the number and type of contact failures (micro cracks) reveals that at micro level tensile failures occur first, followed by mobilization of residual friction. Three distinct stages of stress–strain curve can be well identified by the accumulated number of contact failures and the mode of contact failures. 相似文献
74.
Recovery of Staphylococcus aureus in Gray Mugil cephalus Roe (Bottarga): Investigation by an Integrated Cultural/Molecular Approach 下载免费PDF全文
Valeria Brandas Germano Orrù Valentina Carraro Adriana Sanna Giovanni Brajon Fulvio Salati Clara Sanna Maria laura Ciusa Mauro Meloni Valentina Coroneo 《Journal of food science》2015,80(6):M1285-M1290
In the Mediterranean area, salted and dried roe from the gray Mugil cephalus “bottarga” represent a speciality food with great commercial value. Bottarga is currently produced by a traditional handmade process and, the risk of human bacterial contamination during its manufacturing is still unknown; in this perspective the foodborne pathogen Staphylococcus aureus could potentially contaminate this product due to poor sanitation or bad handling during processing. The aim of this work is: to evaluate the contamination level of foodborne pathogens at different product manufacturing stages and, in addition, to describe a fast and realizable method for the rapid detection of S. aureus in bottarga samples in the field. A cultural procedure was initially used to investigate the occurrence of S. aureus and the other main foodborne pathogens in bottarga samples at the different manufacturing stages (from roe to final product). In addition, a molecular approach was used to rapidly determine the presence of total bacteria, S. aureus, and its potential toxigenicity. Of the 194 specimens analyzed, we identified: Clostridium perfringens, Enterococcus spp. and Enterobacteriaceae. However, some samples resulted as being contaminated with S. aureus (4% in roe and 8.7% in the final product). During the bottarga manufacturing process, we observed an increase in pathogen levels (from 102 to 105 CFU/g) in contaminated samples, and entA and entB genotypes were identified. Reconstruction experiments suggest that the fresh roe and the bottarga (not completely dried) could represent a risk for the contamination and growth of pathogen bacteria. 相似文献
75.
Marilena Giangi Fulvio Stella Tomasz A. Kowalewski 《Computing and Visualization in Science》1999,2(2-3):123-130
A numerical and experimental study of unsteady natural convection during freezing of water is presented. The mathematical
model for the numerical simulations is based on the enthalpy-porosity method in vorticity-velocity formulation, equations
are discretised on a fixed grid by means of a finite volume technique. A fully implicit method has been adopted for the mass
and momentum equations. Experiments are performed for water in a differentially heated cube surrounded by air. The experimental
data for natural convection with freezing in the cavity are collected to create a reference for comparison with numerical
results. The method of simultaneous measurement of the flow and temperature fields using liquid crystal tracers is used. It
allows us to collect transient data on the interface position, and the temperature and velocity fields. In order to improve
the capability of the numerical method to predict experimental results, a conjugate heat transfer problem was solved, with
finite thickness and internal heat conductivity of the non-isothermal walls. These results have been compared with the simulations
obtained for the idealised case of perfectly adiabatic side walls, and with our experimental findings. Results obtained for
the improved numerical model shown a very good agreement with the experimental data only for pure convection and initial time
of freezing process. As time passes the discrepancies between numerical predictions and the experiment became more significant,
suggesting a necessity for further improvements of the physical model used for freezing water.
Received: 30 April 1999 / Accepted: 17 June 1999 相似文献
76.
A numerical assessment of the load bearing capacity of externally pressurized moderately thick tubes
Leone Corradi Valentino Di Marcello Lelio Luzzi Fulvio Trudi 《International Journal of Pressure Vessels and Piping》2009,86(8):525-532
The collapse behavior of cylindrical shells pressurized from outside is examined. Attention is focused on tubes of moderate thickness, as required by very deep water pipelines or some innovative nuclear power plant proposals. Their collapse is expected to be dominated by yielding but, because of the decreasing nature of the post-collapse evolution, interaction with instability is likely to be significant enough to demand consideration. At present, no quantitative assessment of such effect is available, because little study has been devoted to tubes in this thickness range.Plasticity–instability interaction is activated by imperfections and to assess their influence on a systematic numerical study is undertaken. Computations produce a meaningful measure of the collapse pressure and it is proposed that the allowable pressure be determined on its basis, by introducing a suitable safety factor. This is chosen so that results reproduce those provided by presently accepted procedures in the well explored and reliable range of medium-thin tubes. When the same factor is applied to thicker tubes, the resulting allowable pressure is significantly higher than the values suggested by codes, which apparently react to the present lack of knowledge by assuming an extremely conservative attitude. 相似文献
77.
Maria Teresa Rubino Dr. Mariangela Agamennone Dr. Cristina Campestre Dr. Giuseppe Fracchiolla Dr. Antonio Laghezza Dr. Fulvio Loiodice Prof. Elisa Nuti Dr. Armando Rossello Prof. Paolo Tortorella Prof. 《ChemMedChem》2009,4(3):352-362
Selective MMP inhibitors : Eleven α‐sulfonylphosphonates were synthesized and tested as MMP inhibitors. The IC50 values for most of them are in the nanomolar range against MMP‐2, ‐8, ‐13, and ‐14, with an interesting selectivity profile versus MMP‐9.
78.
The role of vitamin E in the protection against iron dependent lipid peroxidation was studied in rat liver microsomes and
Triton-dispersed microsomal lipid micelles. In these systems, an antioxidant effect of vitamin E at a physiological ratio
to phospholipids could be observed only in the presence of phospholipid hydroperoxide glutathione peroxidase (PHGPX) and glutathione.
The rationale of this cooperation is discussed on the basis of the hydroperoxyl radical scavenging capacity of vitamin E and
the reduction of membrane hydroperoxides by PHGPX. The scavenging of lipid hydroperoxyl radicals by vitamin E, although inhibiting
propagation of the peroxidative chain, produces lipid hydroperoxides from which ferrous iron generates alkoxyl radicals that
react with vitamin E almost as fast as with fatty acids. Therefore, only if membrane hydroperoxides are continuously reduced
by this specific peroxidase does the scavenging of hydroperoxyl radicals by vitamin E lead to an effective inhibition of lipid
peroxidation. 相似文献
79.
Perceived orientation of axis of rotation and accuracy in discriminating fixed-axis from nonfixed-axis rotations were investigated for orthographic projections of three-dimensional rotating objects. The principal findings were (1) the slant of the axis of rotation was systematically misperceived; (2) in both two-view and multiview displays, the perceived slant of the axis of rotation was well-predicted by the ratio between the deformation (a property of the first-order optic flow) and the component parallel to the image plane of the global velocity vector; (3) if this ratio was kept constant in each frame transition of the stimulus sequence (or it was varied), then the stimuli tended to be judged as fixed-axis rotations (or as nonfixed-axis rotations), regardless of whether they simulated a fixed-axis rotation or not; and (4) the tilt of the axis of rotation was perceived in two-view displays with a very small error. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
80.
The relationship between simulated and judged depth separations for pairs of probe dots on planar surface patches was examined in a series of 6 experiments. The simulated slant of the patches was varied without varying the simulated depth separation of the probe dots by varying the depth gradient orthogonal to the direction determined by the probe dots on the image plane. Judged depth separation varied with mean slant for constant simulated depth separations. When observers judged depth separations along a closed path, the integral of the signed depths did not sum to zero, as would be required in Euclidean geometry. These results are inconsistent with the view that the mapping between simulated and perceived 3-D structure is affine and indicate that, in general, the perceived structure cannot be represented in either a Euclidean space or an affine space. Moreover, these results are consistent with a first-order temporal analysis of the optic flow. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献