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排序方式: 共有387条查询结果,搜索用时 15 毫秒
1.
Burcu Selen alayan Ahmet K. Avc Z. lsen
nsan A. Erhan Aksoylu 《Applied Catalysis A: General》2005,280(2):181-188
Indirect partial oxidation (IPOX) of propane was studied over bimetallic 0.2 wt.% Pt–15 wt.% Ni/δ-Al2O3 catalyst in the 623–743 K temperature range. The unreduced and reduced forms of the catalyst were characterized by ESEM–EDAX and X-ray diffraction (XRD). In the IPOX tests, the effects of steam to carbon ratio (S/C), carbon to oxygen ratio (C/O2) and residence time (W/F (gcat h/mol HC)) on the hydrogen production activity, selectivity and product distribution were studied in detail. The effect of temperature program applied (increasing from 623 to 743 K, ITP; decreasing from 743 to 623 K, DTP) during reaction was also tested. The results showed that the Pt–Ni bimetallic system has superior performance characteristics compared to the monometallic catalysts reported in literature. The reason is thought to be the utilization of the catalyst particles as micro heat exchangers during IPOX; the heat generated by Pt sites during exothermic total oxidation (TOX) being readily transferred through the catalyst particles acting as micro heat exchangers to the Ni sites, which promote endothermic steam reforming (SR). The optimal conditions were found as S/C = 3, C/O2 = 2.70 and W/F = 0.51 gcat h/mol HC for IPOX of propane on the basis of high hydrogen productivity and selectivity between 623 and 748 K for the experimental conditions tested. The thermo-neutral points obtained showed the sustainability of reaction in terms of energy. 相似文献
2.
Recently, polyvinylidene fluoride (PVDF) based nanocomposites have attracted much attention for next-generation wearable applications such as promising piezoelectric energy harvesters (nanogenerators), energy storage devices, sensing devices, and biomedical devices due to their high flexibility, and high dielectric and piezoelectric properties. 3D printing technology, PVDF based piezoelectric nanocomposites, the studies based on 3D printing of PVDF based piezoelectric nanocomposites by inkjet printing and fused deposition modeling, and enhancements of energy harvesting and storage performance of nanocomposites by structural design are comprehensively overviewed here. An insight is provided into 3D printing techniques, structure and properties of PVDF based polymers, various nanofillers and production methods for nanocomposites, solutions to enhance β phase (crystallinity) of PVDF, and improvements of nanocomposites’ breakdown strength, discharged energy density, and piezoelectric power output by mentoring structural design. 相似文献
3.
The use of ultrasonic energy in dyeing cotton fabrics with monochlorotriazine and vinylsulphone reactive dyes has been studied spectrophotometrically. The dyeings carried out conventionally and by the use of ultrasonic techniques were compared in terms of percentage exhaustion, total amount of dye transferred to the washing bath after dyeing, fastness properties and colour values of the dyed materials. Overall results have shown that the use of ultrasound in reactive dyeing of cellulosic fabrics can result in energy savings, less water consumption, increased depth of colour and better process conditions. 相似文献
4.
G.?BiresawEmail author A.?Adhvaryu S.?Z.?Erhan C.?J.?Carriere 《Journal of the American Oil Chemists' Society》2002,79(1):53-58
The steel/steel boundary friction properties of soybean oil (SBO) and high-oleic soybean oil (HOSBO) are compared. HOSBO is
significantly more saturated than SBO and more oxidatively stable. Changes in degree of unsaturation affect lateral interactions
of adsorbate molecules, which in turn affects their adsorption and, hence, their boundary lubrication properties. To investigate
this possibility, the free energies of adsorption (ΔG
ads) of SBO, HOSBO, and methyl laurate (ML) were determined from the analysis of friction-derived adsorption isotherms using
the Langmuir and Temkin adsorption models. The results showed a stronger adsorption for the vegetable oils than for ML, an
indication of multiple interactions between the ester groups of the triglycerides and the steel surface. The result also showed
no difference in the ΔG
ads values of SBO and HOSBO obtained using either the Langmuir or Temkin models. This was interpreted as an indication of the
lack of appreciable net lateral interaction between triglyceride adsorbates. 相似文献
5.
Several fatty derivatives with bulky moieties were prepared by treatment of epoxidized isopropyl oleate with a number of alcohols
in the presence of sulfuric acid catalyst to provide a series of α-hydroxy ethers in good yield. The materials were analyzed
for cold flow performance through cloud point and pour point determinations. The most promising α-hydroxy ether produced in
this study, with respect to both low temperature behavior and economic criteria, was isopropyl 9(10)-(2-ethylhexoxy) 10(9)-hydroxystearate,
which has a cloud point of −23°C and pour point of −24°C. 相似文献
6.
ABSTRACT Treatments of phenol formaldehyde producing wastewater (PFPW) by electrooxidation (EO) and electro-Fenton (EF) successive processes were carried out in a batch electrolytic reactor using graphite (Gr) and stainless steel (Ss) electrodes. After the completion of the EO process, the wastewater was further treated with EF process. The influence of operating variables such as current density, operating time, initial pHi and H2O2 concentration was evaluated for removals of phenol, TOC and COD in PFPW. Gr/Gr, Gr/Ss or Ss/Ss and Ss/Gr electrode pair were used as anode and cathode. The best removal efficiency in the EO process was obtained with Gr/Gr (93%) as compared to Gr/Ss (82%), Ss/Ss (63%) and Ss/Gr (55%). The removal efficiencies for the EO process using Gr-Gr electrode pair were obtained as 93% for phenol, 61% for COD and 44% for TOC at initial pHi 7,5 g/L of NaCl, 50 mA/cm2 and 5 h. In the EF process, the removal efficiencies at pHi 3,5 mA/cm2 and 30 mM H2O2 and 45 min were 100% for phenol, 76% for COD and 59% for TOC. This study provided that the successive processes are an effective method for the removal of phenolic compounds from the wastewater. 相似文献
7.
New epoxidized soybean oil (ESO)/clay nanocomposites have been prepared with triethylenetetramine (TETA) as a curing agent. The dispersion of the clay layers is investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM data reveal the intercalated structure of ESO/clay nanocomposites has been developed. The thermogravimetric analysis exhibits that the ESO/clay nanocomposites are thermally stable at temperatures lower than 180 °C, with the maximum weight loss rate after 325 °C. The glass transition temperature, Tg, about 7.5 °C measured by differential scanning calorimetry (DSC) and Tg about 20 °C measured by dynamic mechanical study have been obtained. The difference in the Tg between DSC and dynamic measurements may be caused by different heating rate. The nanocomposites with 5-10 wt% clay content possess storage modulus ranging from 2.0×106 to 2.70×106 Pa at 30 °C. The Young's modulus (E) of these materials varies from 1.20 to 3.64 MPa with clay content ranging from 0 to 10 wt%. The ratio of epoxy (ESO) to hydrogen (amino group of TETA) greatly affects dynamic and tensile mechanical properties. At higher amount of TETA, the nanocomposites exhibit stronger tensile and dynamic properties. 相似文献
8.
Erhan Kilinc Anthony M. T. Bell Paul A. Bingham Russell J. Hand 《Journal of the American Ceramic Society》2021,104(8):3921-3946
Crystallization, mechanical properties, and workability are all important for the commercialization and optimization of silicate glass compositions. However, the inter-relations of these properties as a function of glass composition have received little investigation. Soda-lime-silica glasses with Na2O-MgO-CaO-Al2O3-SiO2 compositions relevant to commercial glass manufacture were experimentally studied and multiple liquidus temperature and viscosity models were used to complement the experimental results. Liquidus temperatures of the fabricated glasses were measured by the temperature gradient technique, and Rietveld refinements were applied to X-Ray powder diffraction (XRD) data for devitrified glasses, enabling quantitative determination of the crystalline and amorphous fractions and the nature of the crystals. Structural properties were investigated by Raman spectroscopy. Acoustic echography, micro-Vicker's indentation, and single-edge-notched bend testing methods were used to measure Young's moduli, hardness, and fracture toughness, respectively. It is shown that it is possible to design lower-melting soda-lime-silica glass compositions without compromising their mechanical and crystallization properties. Unlike Young's modulus, brittleness is highly responsive to the composition in soda-lime-silica glasses, and notably low brittleness values can be obtained in glasses with compositions in the wollastonite primary phase field: an effect that is more pronounced in the silica primary phase field. The measured bulk crystal fractions of the glasses subjected to devitrification at the lowest possible industrial conditioning temperatures indicate that soda-lime-silica glass melts can be conditioned close to their liquidus temperatures within the compositional ranges of the primary phase fields of cristobalite, wollastonite, or their combinations. 相似文献
9.
Compaction of Schedules and a Two-Stage Approach for Duplication-Based DAG Scheduling 总被引:1,自引:0,他引:1
Bozdag D. Ozguner F. Catalyurek U.V. 《Parallel and Distributed Systems, IEEE Transactions on》2009,20(6):857-871
Many DAG scheduling algorithms generate schedules that require prohibitively large number of processors. To address this problem, we propose a generic algorithm, SC, to minimize the processor requirement of any given valid schedule. SC preserves the schedule length of the original schedule and reduces processor count by merging processor schedules and removing redundant duplicate tasks. To the best of our knowledge, this is the first algorithm to address this highly unexplored aspect of DAG scheduling. On average, SC reduced the processor requirement 91, 82, and 72 percent for schedules generated by PLW, TCSD, and CPFD algorithms, respectively. SC algorithm has a low complexity (O{N}3) compared to most duplication-based algorithms. Moreover, it decouples processor economization from schedule length minimization problem. To take advantage of these features of SC, we also propose a scheduling algorithm SDS, having the same time complexity as SC. Our experiments demonstrate that schedules generated by SDS are only 3 percent longer than CPFD (O{N}4), one of the best algorithms in that respect. SDS and SC together form a two-stage scheduling algorithm that produces schedules with high quality and low processor requirement, and has lower complexity than the comparable algorithms that produce similar high-quality results. 相似文献
10.
This article aims to explore the impact of the integration of risk factors into delayed milestones for construction projects. A simulation model was developed to determine the impact of schedule variability on cost estimation. To generate random scenarios a Monte Carlo Simulation (MCS) technique was applied. The developed model computes the cost impact of delayed milestone in the expected budget. Using a risk integration approach revealed the critical time frame that may lead to a budget deficit for a project. As a result, a number of cost-sensitive risk factors and schedule delays were identified for the critical time period where the risk of budget deficit increases. The method of integration proposed in this article highlights the priority of risk factors and schedule delays for construction contracts involving Payments at Event Occurrences (PEO). Consequently, the developed method can be useful for practitioners in anticipation of potential increase of costs, hence, prevention of failure due to budget deficit. 相似文献