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排序方式: 共有647条查询结果,搜索用时 15 毫秒
61.
Carbon: 25th Anniversary Article: Chemically Modified/Doped Carbon Nanotubes & Graphene for Optimized Nanostructures & Nanodevices (Adv. Mater. 1/2014) 下载免费PDF全文
62.
Arghya Deb Soumitra Agasti Tapish Saboo Debabrata Maiti 《Advanced Synthesis \u0026amp; Catalysis》2014,356(4):705-710
Biologically and pharmaceutically relevant arylated quinones (Quin‐Ar) have been synthesized via direct C H arylation of a variety of phenols using arylboronic acids. An inexpensive, environmentally friendly iron catalyst, ferric sulphate, Fe2(SO4)3, was employed in this operationally simple and efficient method.
63.
A multistage field emitter based on graphene-linked ZnO nanowire array is realized by means of spin-coating a graphene dispersion (reduced graphene oxide) over a nanostructured platform followed by plasma modification. Spin-coating leads to interlinking of graphene sheets between the neighboring nanowires whereas plasma etching in the subsequent step generates numerous ultra-sharp graphene edges at the nanowire tips. The inherent tendency of graphene to lay flat over a plane substrate can easily be bypassed through the currently presented nanostructure platform based technique. The turn-on and threshold field significantly downshifted compared to the individual components in the cascade emitter. Through the facile electron transfer from nanowires to graphene due to band bending at the ZnO-graphene interface together with multistage geometrical field enhancement at both the nanowire and graphene edges remain behind this enriched field emission from the composite cold cathode. This strategy will open up a new direction to integrate the functionalities of both the graphene array and several other inorganic nanostructure array for practical electronic devices. 相似文献
64.
Grate JW O'Hara MJ Farawila AF Douglas M Haney MM Petersen SL Maiti TC Aardahl CL 《Analytical chemistry》2011,83(23):9086-9091
A sample preparation sequence for actinide isotopic analysis by thermal ionization mass spectrometry (TIMS) is described that includes column-based extraction chromatography as the first separation step, followed by anion-exchange column separations. The sequence is designed to include a wet ashing step after the extraction chromatography to prevent any leached extractant or oxalic acid eluent reagents from interfering with subsequent separations, source preparation, or TIMS ionization. TEVA resin and DGA resin materials, containing extractants that consist only of C, N, O, and H atoms, were investigated for isolation of plutonium. Radiotracer level studies confirmed expected high yields from column-based separation procedures. Femtogram-level studies were carried out with TIMS detection, using multiple monoisotopic spikes applied sequentially throughout the separation sequence. Pu recoveries were 87% and 86% for TEVA and DGA resin separations, respectively. The Pu recoveries from 400 μL anion-exchange column separation sequences were 89% and 93% for trial sequences incorporating TEVA and DGA resin. Thus, a prior extraction chromatography step in the sequence did not interfere with the subsequent anion-exchange separation when a simple wet ash step was carried out in between these column separations. The average measurement efficiency for Pu, encompassing the chemical separation recoveries and the TIMS ionization efficiency, was 2.73% ± 0.77% (2σ) for the DGA resin trials and 2.67% ± 0.54% for the TEVA resin trials, compared to 3.41% and 2.37% (average 2.89%) for two control trials. These compare with an average measurement efficiency of 2.78% ± 1.70%, n = 33 from process benchmark analyses using Pu spikes processed through a sequence of oxalate precipitation, wet ash, iron hydroxide precipitation, and anion-exchange column separations. We conclude that extraction chromatography can be a viable separation procedure as part of a multistep sequence for TIMS sample preparation. 相似文献
65.
Modelling of mode-I stable crack growth under hydrogen assisted stress corrosion cracking 总被引:1,自引:0,他引:1
The paper presents a new strategy based on combined analytical and finite element (FE) solution to hydrogen assisted stress corrosion crack growth. The diffusion process is solved analytically through both one-and two-dimensional modelling. These solutions are adopted with two-dimensional FE based cohesive zone model of crack extension study. The results fit well with published experimental data and show improvement over the predictions by full FE approach. The new solution approach helps to reduce time required for simulation/computation. The study has produced a relationship between concentration dependent reduction in cohesive strength and plastic strain rate. 相似文献
66.
Interfacial reactions and electrical properties of RF sputter deposited HfTaOx high-k gate dielectric films on Si1 − xGex (x = 19%) are investigated. X-ray photoelectron spectroscopic analyses indicate an interfacial layer containing GeOx, Hf silicate, SiOx (layer of Hf-Si-Ge-O) formation during deposition of HfTaOx. No evidence of Ta-silicate or Ta incorporation was found at the interface. The crystallization temperature of HfTaOx film is found to increase significantly after annealing beyond 500 °C (for 5 min) along with the incorporation of Ta. HfTaOx films (with 18% Ta) remain amorphous up to about 500 °C anneal. Electrical characterization of post deposition annealed (in oxygen at 600 °C) samples showed; capacitance equivalent thickness of ~ 4.3-5.7 nm, hysteresis of 0.5-0.8 V, and interface state density = 1.2-3.8 × 1012 cm− 2 eV− 1. The valence and conduction band offsets were determined from X-ray photoelectron spectroscopy spectra after careful analyses of the experimental data and removal of binding energy shift induced by differential charging phenomena occurring during X-ray photoelectron spectroscopic measurements. The valence and conduction band offsets were found to be 2.45 ± 0.05 and 2.31 ± 0.05 eV, respectively, and a band gap of 5.8 ± 05 eV was found for annealed samples. 相似文献
67.
S. Chattopadhyay L. K. Bera C. K. Maiti S. K. Ray P. K. Bose D. Dentel L. Kubler J. L. Bischoff 《Journal of Materials Science: Materials in Electronics》1998,9(6):403-407
PtSi/p-strained-Si1-xGex (x=0.19 and x=0.29) Schottky barrier diodes have been fabricated and characterized for the determination of barrier height, ideality factor and the interface state density distribution with energy. Diodes having an epitaxial layer thickness of 20 and 52 nm were modeled with emphasis on comparison with experiment. To achieve better agreement with experimental data, an interfacial layer and associated series resistance were included in the model. The capacitance–voltage (C–V) technique has been used for the determination of the energy distribution of interface state density. The interface state density distribution for the Si0.81Ge0.19 and Si0.71Ge0.29 diodes is found to decrease with increasing energy from the valence band edge. 相似文献
68.
Parental illness can have a profound impact on family relationships and children's behaviour. The amount and nature of communication between parents and children about the illness can play an important role, both positively and negatively, in mediating the outcomes. When children have a disability, families can be reluctant to communicate with them about family difficulties. They are often concerned about the impact that parental unavailability may have on their child's life. This paper reports on three families in which the mother was diagnosed with breast cancer and one child in the family had a disability. The extent and specific characteristics of their communication about the maternal illness with their children, behavioural changes in the children, explanations of communication strategies and attributions of behavioural changes are described. Family coping strategies are examined with reference to Lazarus's process model of stress and coping and the use of either problem-focused or emotion-focused strategies. Implications for possible clinical interventions are proposed. In particular it is suggested that families be offered consultation about: what children might understand; ways in which to communicate effectively; and strategies for coping with the long-term implications of serious parental illness. 相似文献
69.
Maiti B. Tobin P.J. Okada Y. Reid K.G. Ajuria S.A. Hegde R.I. Kaushik V. 《Electron Device Letters, IEEE》1996,17(6):279-281
Reoxidation of an oxynitride gate dielectric grown by NO anneal of thermal oxide has been studied. This process has demonstrated ~3-5X improvement of QBD of active edge intensive capacitors in comparison to thermal oxide, N2O and NO oxynitride. This improvement is believed to be due to the reduction of local thinning of the gate dielectric at the field oxide edge which also reduces local build-up of positive charge near the gate electrode at the isolation edges 相似文献
70.
M. Maiti 《International Journal of Fracture》1979,15(4):389-393
Dislocation layers have been utilized to study the effect of rigid inclusion on the crack extension in an infinite body and thereby to derive the crack extension condition from Irwin's criterion. Some particular cases have also been considered.
Résumé On a eu recours aux couches de dislocation pour étudier l'effet d'une inclusion rigide sur l'extension d'une fissure dans un corps infini et déterminer en conséquence les conditions d'extension d'une fissure en utilisant le critère d'Irwin. Certains cas particuliers ont également été considérés.相似文献