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111.
The phase segregation in P3HT:PCBM blend films has been investigated from an experimental and theoretical viewpoint. Optical microscopy, atomic force microscopy, scanning electron microscopy and X-ray diffraction show that thermal annealing of P3HT:PCBM blend films leads to the formation of PCBM aggregates. These aggregates are composed of dense randomly packed ∼50 nm PCBM crystallites with an overall aggregate density of ∼0.85 g cm−3. By applying the critical radius of nucleation for PCBM and the Stokes-Einstein equation for mobility of PCBM in a P3HT matrix, a model is developed which explains the formation of both crystallites and aggregates. 相似文献
112.
Enriched concentrations of metal contaminants have been reported in surficial sediments and tissues of aquatic organisms in Sydney estuary, New South Wales, Australia. Dietary ingestion of contaminated, suspended sediments is potentially a major route of metal exposure to the filter-feeder Saccostrea glomerata. A dynamically coupled biokinetic-equilibrium bioaccumulation model was developed to explore sediment-oyster-metal uptake interactions. The biokinetic component simulated the sediment dynamics and oyster uptake and loss kinetics while the ion equilibrium model accounted for the metal speciation reactions. Results of a laboratory-based mesocosm experiment as well as data from the literature were used to parameterise the model. The model demonstrated a good fit of the experimental data and indicated that dissolved and particulate organic matter were important determinants of metal bioavailability to this species. The model served also as a unique tool to formulate testable hypotheses and help to better explain the bioaccumulation patterns observed from the experiment. 相似文献
113.
A novel silica-functionalized ammonium tungstate interphase catalyst has been reported as a non-nitric acid route for adipic acid production from one-pot oxidative cleavage of 30% hydrogen peroxide and catalytic amounts of p-toluenesulfonic acid (PTSA). The catalyst has been simply prepared by commercially available starting material. The structure of the catalyst has been investigated using FT-IR spectroscopy, atomic absorption, TEM, SEM and XRD analysis. The catalyst has shown good to high activity even up to 10 runs of reaction. Simple preparation of the catalyst, avoids using harmful phase transfer catalyst (PTC) and/or chlorinated additives are among the other benefits of this work. 相似文献
114.
《International Journal of Hydrogen Energy》2019,44(16):8214-8222
Development of highly efficient electrocatalysts to produce hydrogen has been a significant topic over the past few decades. Currently, the platinum metal group shows the best catalytic performance for the hydrogen evolution reaction (HER), but the high cost and low abundance of these materials limit their wider application. Therefore, we synthesized transition-metal-based NiCoS along with carbon dots (C-dots) as a structure-directing agent by a hydrothermal method. We also synthesized sulfur-doped NiCo, where the sulfur enhances the conductivity of the catalysts. Herein, the synthesis temperatures were changed in the range from 120 to 240 °C. Among all, NiCoS synthesized at 150 °C shows the best HER performance capabilities. In more detail, NiCoS prepared at this temperature exhibits an onset potential of 96 mV and an overpotential of 232 mV. Especially, as-prepared NiCoS nanoflower subjects to long-term stability over 20 h at a current density of 10 mA/cm2, making it a promising low-cost candidate for hydrogen production. 相似文献
115.
《International Journal of Hydrogen Energy》2019,44(16):8341-8346
Density Functional Theory (DFT) calculations were employed to study a series of coinage metal-hydrogen associations formulated as [M(Η2)n][A] (M = CuI, AgI or AuI, n = 1–5). The [M(Η2)n][A] salts utilize both their anions and cations for H2 storage. The [M(Η2)n]+ cations could be stabilized in the solid state by voluminous counter-anions, i.e. the [(H3B) (BH2NH2)5(NH2)]-, [B(CNBH3)3]- and [B12H12]- anions. The estimated bond dissociation energies (BDEs) of the M···(η2-H2) bonds are 5–17, 4–11 and 1–26 kcal/mol for the [Cu(Η2)4]+, [Ag (Η2)4]+ and [Au (Η2)4]+ cationic species respectively, while the fifth H2 molecule is estimated to be very loosely associated to the metal center. Four H2 molecules could be exploited from the [Cu(Η2)n][A] and [Ag (Η2)n][A] molecules in addition to the amount of H2 stored in the anion [A]-. Among the [M(Η2)n][A] salts optimal gravimetric, kinetic and thermodynamic properties and relatively low cost, are predicted for [Cu(Η2)n][(H3B) (BH2NH2)5(NH2)]. 相似文献
116.
《International Journal of Hydrogen Energy》2019,44(39):21527-21535
Carbon materials have been demonstrated as excellent carriers for preparing supported metal nanocatalysts in catalytic applications. However, numerous chemical activators including strong acids and bases were applied, leading to the entire process dangerous and hazardous. Eco-friendly, economic, and convenient synthesis of carbon materials with desired properties as supports for metal nanoparticle (NP) stabilization to boost performance is important but remains challenging. Here, we developed a facile and eco-friendly strategy to synthesize porous carbon nanosheets (PCNs) with ultrahigh specific surface area (2575.1 m2/g) via pyrolysis the mixture of potassium oxalate and glucose. The resultant PCNs can be used as ideal platform for in-situ distribution of small Rh NPs (Rh/PCNs) as efficient catalysts in hydrogen production from ammonia borane (AB) under ambient conditions. Specifically, Rh/PCNs displayed high activity for AB hydrolysis, with a turnover frequency (TOF) of 513.2 min−1. Small and well-distributed Rh NPs on PCNs with large catalytically active surface atoms are contributed to the high catalytic property of Rh/PCNs for the reaction. Present study has demonstrated that the PCNs is a superior catalyst support for preparing a series of metal NPs in other catalytic applications beyond hydrolysis reaction. 相似文献
117.
《International Journal of Hydrogen Energy》2019,44(23):11675-11683
The development of cost-effective heterogeneous catalysts for the dehydrogenation of formic acid (FA) is the key challenge for the commercialization of FA as a hydrogen-storage medium. Herein, PdCoNi nanoparticles (NPs) with different element ratios supported on N-doped carbon nanosheets (N-CN) were designed, which exhibit excellent catalytic dehydrogenation performance for FA. Compared with PdCoNi NPs loaded on the carbon nanosheets (CN), the introduction of pyrrolic N to CN induces the formation of ultrafine, monodispersed and amorphous Pd0.6Co0.2Ni0.2 NPs with a size of 1.60 nm, which significantly increases the number of active sites and the instant contact between FA and catalysts. The as-prepared Pd0.6Co0.2Ni0.2/N-CN catalyst shows more than 99% conversion and 100% H2 selectivity at room temperature, with a record-high initial turnover frequency (TOFinitial) of 1249.0 h−1 among non-noble containing Pd-based catalysts, which demonstrates the high potential of Pd0.6Co0.2Ni0.2/N-CN as a practical catalyst for the hydrogen generation from FA. 相似文献
118.
119.
This research is a response to the universal use of social media by students for academic-related purposes. It bridges a gap in knowledge in relation to the value and use of social media as effective teaching and learning tool in higher education in developing countries. A pre-tested questionnaire survey was self-administered to faculty members in the eight public Egyptian higher institutions offering tourism and hotel management programs. The results showed that social media have a great value for academic-related purposes, particularly as teaching and learning tool; however, the actual use by faculty was at a minimal level. In-depth interviews were conducted to identify the perils, barriers and concerns for the minimal use. Several barriers were identified with some specific to developing countries' context. Nonetheless, there was consensus by faculty that if these barriers were overcome, social media could be developed as an innovative and effective tool for teaching and learning. Implications for researchers and policy makers are discussed. 相似文献
120.
A mass spectrometry-based electronic nose (MS e-nose) was used to measure changes in rice quality during storage at different storage conditions. Rice was stored for 4 months at four different temperatures (0 °C, 20 °C, 30 °C, and 40 °C) and tested for fat acidity, sensory characteristics, and flavor pattern analysis using the MS e-nose. When the rice was stored for long durations at higher temperatures, fat acidity increased and sensory quality was low. Flavor volatile profiles of the rice determined by MS e-nose revealed a tendency for the results to separate into three groups (months 1 + 2, 3, and 4). Volatile profile changes in rice during storage depended on the storage time, regardless of storage temperature. It is likely that the fat acidity and sensory evaluation results, which were related, could be distinguished by their volatile-producing metabolic activities. Accordingly, MS e-nose system was successfully used to screen and qualitatively evaluate stored rice. 相似文献