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11.
Abril Zoraida Graciano-Verdugo Herlinda Soto-Valdez Elizabeth Peralta Pavlov Cruz-Zárate Alma Rosa Islas-Rubio Saúl Sánchez-Valdes Armida Sánchez-Escalante Natalia González-Méndez Humberto González-Ríos 《Food research international (Ottawa, Ont.)》2010,43(4):1073-1078
The migration of α-tocopherol (α-T) from low density polyethylene (LDPE) films, added with 20 (film A) and 40 mg g?1 (film B) to corn oil for 12 weeks at 5, 20 and 30 °C was determined. A LDPE film added with no α-T was used as control (film C). Diffusion coefficient (D) values for the film A system were 1.4 × 10?11, 7.1 × 10?11 and 30.3 × 10?11 cm2 s?1 at 5, 20 and 30 °C, respectively. Meanwhile, D values for the film B system were 1.3 × 10?11, 9.6 × 10?11 and 51.1 × 10?11 cm2 s?1 at the same temperatures. The activation energy (Ea) for the diffusion of α-T was 126.5 (film A) and 105.9 kJ mol?1 (film B). The effect of the migration of α-T on the oxidative stability of corn oil was evaluated by monitoring hexanal content by solid phase micro-extraction (SPME) and gas chromatography. The hexanal content in the oil showed that both films added with α-T resulted suitable to maintain the oxidative stability of the oil for about 16 weeks at 30 °C, compared to 12 weeks for the oil in contact with the film C. 相似文献
12.
With the objective of minimizing the total execution time of a parallel program on a distributed memory parallel computer, this paper discusses the selection of an optimal supernode shape of a supernode transformation (also known as tiling). We identify three parameters of a supernode transformation: supernode size, relative side lengths, and cutting hyperplane directions. For supernode transformations on algorithms with perfectly nested loops and uniform dependencies, we prove the optimality of a constant linear schedule vector and give a necessary and sufficient condition for optimal relative side lengths. We also prove that the total running time is minimized by a cutting hyperplane direction matrix from a particular subset of all valid directions and we discuss the cases where this subset is unique. The results are derived in continuous space and should be considered approximate. Our model does not include cache effects and assumes an unbounded number of available processors, the communication cost approximated by a constant, uniform dependences, and loop bounds known at compile time. A comprehensive example is discussed with an application of the results to the Jacobi algorithm. 相似文献
13.
Aureli P Ferrini AM Mannoni V Hodzic S Wedell-Weergaard C Oliva B 《International journal of food microbiology》2003,83(3):325-330
The susceptibility of 148 strains of Listeria monocytogenes isolated from food to antibiotics currently used in veterinary and human therapy was determined by standard agar dilution and disk diffusion methods. The antibiotics included amikacin, amoxicillin, cefazolin, chloramphenicol, erythromycin, flumequine, fosfomycin, gentamicin, kanamycin, lincomycin, oxytetracycline, rifampicin, spiramycin, streptomycin, tetracycline, tobramycin and vancomycin. Soussy's breakpoints and MIC(50)-MIC(90) values were used to classify the strains into sensitive, moderately sensitive and resistant groups.This work is part of a wider surveillance program on listeriosis started in Italy in 1995. 相似文献
14.
René R. Colditz Joanna Acosta-Velázquez José Reyes Díaz Gallegos Alma Delia Vázquez Lule María Teresa Rodríguez-Zúñiga Pedro Maeda 《International journal of remote sensing》2013,34(20):6426-6445
Change detection is one of the primary applications of remote-sensing data, and many techniques have been developed during the past three decades. Although frequently criticized and despite many alternatives, due to its simplicity and intuitive manner, post-classification change detection still remains one of the most applied techniques. Many studies in the field of change detection analysis acknowledge, for instance, the impact of misregistration, inconsistencies in classification schemes or differences in methods for image interpretation. However, there are additional, rarely studied influences that can cause large errors in change detection results, including integrating multi-resolution data, the adjacency effect and the minimum mapping units (MMUs) that are applied to the classification before change detection. This study demonstrates these effects for the complex land cover of the Alvarado mangrove area at the Mexican Gulf Coast, employing 10 m Système Pour l'Observation de la Terre 5 (SPOT-5) high geometric resolution (HRG)‐based and 57 m Landsat Multispectral Scanner (MSS) classifications. As a baseline, the proportion of the fine spatial resolution classes within the coarse spatial resolution cells were derived, from which proportional change matrices were computed. The analysis employs difference measures to compare change matrices and proportional maps. The impact of various tested resampling functions was negligible if coarse resolution data were refined. For coarsening fine spatial resolution data, change matrix comparison was comparatively small but yielded differences of approximately 20% in spatially explicit measures. Incorrect positional alignment indicated differences of up to 5% in the change matrix for a misregistration of 100 m and even higher spatially explicit differences (28%). The discrepancies due to the adjacency effect were rather low. MMUs of 25 ha resulted in differences of up to 36% in the change matrix. The magnitude of the discrepancies of all studied effects depends on the class diversity in the map, and some can also be related to the difference in spatial resolution. 相似文献
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Isomerization is used in refining industry to upgrade gasoline. Since it is an important process, it is desirable to analyze the reactions that take place in the process. In this paper, the isomerization of a mixture of hydrocarbons was modeled by solving the chemical equilibrium of the system. A direct application of the chemical equilibrium solution cannot reproduce experimental results. However, when some of the system reactions are molar extent limited, the solution can reproduce published experimental data. 相似文献
18.
The objective of this note is to present a solution to the decentralized estimation and control problem for linear discrete-time varying systems, composed of overlapping subsystems. The solution is based on the expansion-contraction framework of the inclusion principle. It is shown how decentralized estimation and control laws can be independently computed for the expanded system, and then contracted for implementation in the original system to satisfy the overlapping information structure constraint. 相似文献
19.
We investigate the impact of the prechirp on nonreturn-to-zero (NRZ)-based single-channel and 40-Gb/s/ch wavelength-division-multiplexing systems over standard single-mode fibers by means of numerical simulations. It was shown that prechirping of NRZ pulses improve the total transmission length and make the NRZ pulses more robust to Kerr-nonlinearities 相似文献
20.
The initial microstructures of two wheat flours (hard wheat flour and soft wheat flour) and flour components (starch, gluten, soluble pentosans and insoluble pentosans) were observed by scanning electron microscopy (SEM) and the changes in microstructure during hydration were described using environmental SEM (ESEM). SEM images permitted observation of the classical microstructure of wheat flour particles and starch granules. The initial microstructure of the purified fractions of flour components (gluten, soluble pentosans and insoluble pentosans) seemed largely dependent on the purification techniques, and could not thus directly be used to describe their in situ behavior during flour processing. ESEM observations of wheat flours and flour components during hydration first demonstrated slight changes in surface of particles that we associated to apparent swelling effects. The formation of a continuous aqueous phase between particles was observed for long hydration times. 相似文献