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131.
132.
XR Pan-Zhou E Cretton-Scott XJ Zhou MY Xie R Rahmani RF Schinazi K Duchin JP Sommadossi 《Canadian Metallurgical Quarterly》1997,41(11):2502-2510
AZT-P-ddI is an antiviral heterodimer composed of one molecule of 3'-azido-3'-deoxythymidine (AZT) and one molecule of 2',3'-dideoxyinosine (ddI) linked through their 5' positions by a phosphate bond. The metabolic fate of the dimer was studied with isolated rat, monkey, and human hepatocytes and was compared with that of its component monomers AZT and ddI. Upon incubation of double-labeled [14C]AZT-P-[3H]ddI in freshly isolated rat hepatocytes in suspension at a final concentration of 10 microM, the dimer was taken up intact by cells and then rapidly cleaved to AZT, AZT monophosphate, ddI, and ddI monophosphate. AZT and ddI so formed were then subject to their respective catabolisms. High-performance liquid chromatography analyses of the extracellular medium and cell extracts revealed the presence of unchanged dimer, AZT, 3'-azido-3'-deoxy-5'-beta-D-glucopyranosylthymidine (GAZT), 3'-amino-3'-deoxythymidine (AMT), ddI, and a previously unrecognized derivative of the dideoxyribose moiety of ddI, designated ddI-M. Trace extracellular but substantial intracellular levels of the glucuronide derivative of AMT (3'-amino-3'-deoxy-5'-beta-D-glucopyranosylthymidine [GAMT]) were also detected. Moreover, the extent of the formation of AMT, GAZT, and ddI-M from the dimer was markedly lower than that with AZT and ddI alone by the hepatocytes. With hepatocytes in primary culture obtained from rat, monkey, and human, large interspecies variations in the metabolism of AZT-P-ddI were observed. While GAZT and ddI-M, metabolites of AZT and ddI, respectively, as well as AZT 5'-monophosphate (MP) and ddI-MP were detected in the extracellular media of all species, AMT and GAMT were produced only by rat and monkey hepatocytes. No such metabolites were formed by human hepatocytes. The metabolic fate of the dimer by human hepatocytes was consistent with in vivo data recently obtained from human immunodeficiency virus-infected patients. 相似文献
133.
M Lemaire M Trzaska JP Alard J Augerat D Bachelier N Bastid J Boyard C Cavata P Charmensat P Dupieux P Gorodetzky J Gosset T Hennino J Jourdain Le Merdy A D L'H?te B Lucas J Marroncle G Montarou M Parizet J Poitou D Qassoud P Radvanyi B Ramstein A Rahmani M Roy-Stephan O Valette P Zupranski J Cugnon J Vandermeulen 《Canadian Metallurgical Quarterly》1991,43(6):2711-2721
134.
Farzad Rahmani Seyed Jalal Hashemi Hassan Moslemi Naeini Hamed Deylami Azodi 《Journal of Materials Engineering and Performance》2013,22(2):338-344
In hydromechanical deep drawing (HDD), a chamber of fluid replaces the matrix and the final form of part is determined based on the form of rigid punch. Allowable working zone in this process indicates the applicable range of chamber pressure versus drawing ratio to achieve a rupture-free drawing. In this article, the HDD of the square parts was studied using the finite element method (FEM) and the effect of different parameters of the process such as pre-bulging pressure, chamber pressure, and friction coefficient on the working zone was investigated. The results showed that increasing of the friction between blank and die or blank and blank-holder confines the working zone, while by increasing of the friction between blank and punch, the working zone becomes larger. A study was also carried out using experimental setup for verifying the FEM results. Finally, the numerical results were compared with experimental ones. 相似文献
135.
Antibiotic pollution via wastewaters has led to many environmental problems. In this work, to remove ciprofloxacin which is an antibiotic from water, foil photocatalyst of zinc oxide nanowires doped with copper and cerium oxides was applied under UV light irradiation. An empirical model was developed to determine the photocatalyst activity using response surface methodology. The independent variables were the concentrations of precursors, copper and cerium nitrates in the coating solution. The F‐value and p‐value of the model showed the accuracy of the model. The statistical analysis indicated that copper oxide had larger effect on the response than cerium oxide. The optimized catalyst was determined and characterized using ICP, XRD, SEM and MIP techniques. The results of this work which are comparable to those of the previous studies have the advantage of easy separation of the photocatalyst from water without using a centrifuge. 相似文献
136.
Mohammad H. Keshavarz Mohammad Ghorbanifaraz Hadi Rahimi Mehdi Rahmani 《Propellants, Explosives, Pyrotechnics》2011,36(5):424-429
A new method has been introduced to predict the power of important classes of energetic compounds including nitroaromatics, acyclic and cyclic nitramines, nitrate esters and nitroaliphatics. In this method, the predicted specific impulse and the corrected heat of detonation on the basis of H2O‐CO2 arbitrary decomposition, have been used to calculate the power of an explosive with the molecular formula CaHbNcOd as determined by the Trauzl test. The predicted results show good agreement with respect to the measured values for both pure and mixture of explosives. The calculated volume expansions of pure energetic compounds have a root mean square (rms) deviation of 33 cm3 from 73 measured values (corresponding to 58 molecules). For 9 explosive mixtures, the predicted volume expansions have an rms deviation of 39 cm3 from the experimental results. 相似文献
137.
Sample preparation optimization for the simultaneous determination of mycotoxins in cereals 总被引:2,自引:0,他引:2
A. Rahmani S. Jinap F. Soleimany A. Khatib C. P. Tan 《European Food Research and Technology》2011,232(4):723-735
The efficiency of three extraction solvents and three clean-up procedures was compared for simultaneous extraction and purification
of aflatoxins (AFB1, AFB2, AFG1 and AFG2), ochratoxin A (OTA), and zearalenone (ZEA) from spiked cereal samples. The best
recovery rates for all mycotoxins were achieved using methanol: water (80:20) as the extraction solvent and AOZ multi-functional
immunoaffinity column (IAC), as clean up method with recovery values of 61–89%, while that of Oasis HLB and MycoSep 226 were
37–67% and 44–78%, respectively. Then, five variables in the IAC clean-up conditions, including primary conditioning with
phosphate buffer saline (PBS) (0–10 mL) (X1), extract load up volume (10–20 mL) (X2), washing volume with PBS (10–20 mL) (X3),
and eluting solution volumes with methanol (1–3 mL) (X4) and acetic acid (0–1.5 mL) (X5), were optimized for the specific
purification and enrichment of the mycotoxins. Results showed that primary conditioning and PBS washing did not have a significant
effect on the recovery responses of mycotoxins. Optimized conditions were selected as 0, 15, 10, 1.3, and 1.5 mL for X1–X5,
respectively. The recovery rates of AFB1, AFB2, AFG1, AFG2, OTA and ZEA were within 93–104% in spiked rice, under optimal
conditions. LOD and LOQ were 0.0125 and 0.05 ng/g for AFB1 and AFG1, 0.0037 and 0.015 ng/g for AFB2 and AFG2, 0.05 and 0.2 ng/g
for OTA, and 0.5 and 2 ng/g for ZEA, respectively. Extraction of spiked cereal samples with methanol: water (80:20) and clean
up using AOZ IAC column in optimal condition provided recovery range of 77–104% for all targeted mycotoxins. 相似文献
138.
Kiarash Arangdad Andrew Detwiler Curtis D. Cleven Christopher Burk Renzo Shamey Melissa A. Pasquinelli Harold Freeman Ahmed El-Shafei 《应用聚合物科学杂志》2019,136(10):47148
The photodegradation of copolyesters based on 1,4-cyclohexanedimethanol (CHDM), tetramethyl-1,3-cyclobutanediol, and terephthalic acid units was investigated using various analytical methods. Photodegradation products were characterized using Fourier transform infrared (FTIR), liquid chromatography–mass spectrometry (LC–MS), and X-ray Photoelectron spectroscopy (XPS) analysis. The homolytic scission of C-O bonds of ester groups through a Norrish Type I reaction was supported by time of flight secondary ion mass spectrometry and LC–MS results, while nuclear magnetic resonance analysis confirmed hydrogen abstraction from the tertiary carbon of CHDM units in the trans (equatorial-equatorial) conformation. Chain scission through Norrish Type II reaction is also responsible for the formation of carboxylic acid end group. Fluorescence emission from irradiated glycol modified poly(ethylene terephthalate) films demonstrated the formation of mono- and dihydroxyterephthalate species. Furthermore, FTIR and XPS valence band analysis confirmed configurational changes, in the polymer chain due to photodegradation. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47148. 相似文献
139.
Ali Rahmani Firoozjaee Mohammad Hadi Afshar 《Engineering Analysis with Boundary Elements》2009,33(1):83-92
A meshfree method namely, discrete least squares meshless (DLSM) method, is presented in this paper for the solution of elliptic partial differential equations. In this method, computational domain is discretized by some nodes and the set of simultaneous algebraic equations are built by minimizing a least squares functional with respect to the nodal parameters. The least squares functional is defined as the sum of squared residuals of the differential equation and its boundary condition calculated at a set of points called sampling points, generally different from nodal points. A moving least squares (MLS) technique is used to construct the shape functions. The proposed method automatically leads to symmetric and positive-definite system of equations. The proposed method does not need any background mesh and, therefore, it is a truly meshless method. The solutions of several one- and two-dimensional examples of elliptic partial differential equations are presented to illustrate the performance of the proposed method. Sensitivity analysis on the parameters of the method is also carried out and the results are presented. 相似文献
140.
A. Rahmani T. Bouchami S. Bélaïd A. Bousbia-Salah M.H. Boulheouchat 《Applied Thermal Engineering》2009,29(2-3):501-508
Due to their simplicity and passive nature, natural circulation loops have many industrial applications and being increasingly used in many innovative designs as the new generation of nuclear reactor cooling systems. Consequently, special attention is increasingly considered towards their safety issues. In the current framework, a safety aspect related to the loss of feedwater in an industrial D-type steam boiler is assessed. Indeed, loss of feedwater event occurs frequently during steam generator facilities lifetime. Under such conditions, the system integrity is in jeopardy and serious hazards and economic losses could occur. Up to now, specific numerical models have been used to simulate the thermal-hydraulic phenomena occurring under such circumstances. Such models are generally based upon simplified assumptions, and if complex model are performed, their applications are generally restricted to the facility they have been developed for. In the current framework, an attempt is made to apply a multipurpose best estimate (BE) thermal-hydraulic system code, namely, RELAP5/Mod3.2 to simulate steady-state and transient dynamic behaviors of a two-phase natural circulation steam boiler. For this purpose, two loss of feedwater scenarios, with and without the actuation of the boiler control system, have been performed. The analysis results show on one hand the achievement in applying RELAP5 for a conventional boiler system, and on the other hand the efficiency of the control systems to mitigate the accident consequences. 相似文献