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Shufeng Liu Ligong Zhang Linan An Weifeng Fei Helge Heinrich 《Journal of the American Ceramic Society》2005,88(9):2559-2563
The phase transformation of mechanically milled nano-sized γ-alumina particles was investigated. The structures and phase presentation of the powders before and after milling were characterized using X-ray diffraction, transmission electron microscopy, and photoluminescence measurement. The phase transformation kinetics was investigated using differential scanning calorimetry. It was found that significant amounts of defects were generated by milling. These defects dramatically lowered the temperatures and activation energies of the transformation by promoting the nucleation and diffusion. The accumulation of the defects appears to show a logarithmic dependence of milling time. 相似文献
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Hadi Rastin Seyed Hassan Jafari Mohammad Reza Saeb Hossein Ali Khonakdar Udo Wagenknecht Gert Heinrich 《Journal of Polymer Research》2014,21(2):1-13
Visco-elastic and dielectric spectra of multiwalled carbon-nanotube reinforced silicon elastomer nanocomposites were used to study relaxation behavior. SEM photomicrographs shows well dispersion of MWCNT in elastomer matrix. In visco-elastic analysis primary relaxation was studied as a function of temperature (?100 to 100 °C) at frequency 1Hz and strain 1 %. The effect of MWCNT loadings on storage modulus, loss modulus, and loss tangent has been studied. The non-linearity in loss tangent, storage modulus and loss modulus was explained on the basis of MWCNT-elastomer interaction and the inter-aggregate attraction of MWCNT. The secondary β relaxation was studied using dielectric relaxation spectra in the frequency range of 0.1 Hz to 106 Hz. The effect of MWCNT loadings on the complex and real parts of impedance was distinctly visible which has been explained on the basis of interfacial polarization of fillers in a heterogeneous medium and relaxation dynamics of polymer chains in the vicinity of fillers. The dielectric formalism has been utilized to further investigate the conductivity and relaxation phenomenon. The ‘percolation limit’ of the MWCNT in the silicon elastomer was found to be in the range of 4 phr loading. 相似文献
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Anticancer Potential of (Pentamethylcyclopentadienyl)chloridoiridium(III) Complexes Bearing κP and κP,κS‐Coordinated Ph2PCH2CH2CH2S(O)xPh (x=0–2) Ligands 下载免费PDF全文
Gerd Ludwig Ivan Ranđelović Dr. Danijela Maksimović‐Ivanić Dr. Sanja Mijatović Mirna Z. Bulatović Dr. Djordje Miljković Prof. Marcus Korb Prof. Dr. Heinrich Lang Prof. Dr. Dirk Steinborn Prof. Dr. Goran N. Kaluđerović 《ChemMedChem》2014,9(7):1586-1593
Iridium(III) complexes of the type [Ir(η5‐C5Me5)Cl2{Ph2PCH2CH2CH2S(O)xPh‐κP}] (x=0–2; 1 – 3 ) and [Ir(η5‐C5Me5)Cl{Ph2PCH2CH2CH2S(O)xPh‐κP,κS}][PF6] (x=0–1; 4 and 5 ) with 3‐(diphenylphosphino)propyl phenyl sulfide, sulfoxide, and sulfone ligands Ph2PCH2CH2CH2S(O)xPh were designed, synthesized, and characterized fully, including X‐ray diffraction analyses for complexes 3 and 4 . In vitro studies against human thyroid carcinoma (8505C), submandibular carcinoma (A253), breast adenocarcinoma (MCF‐7), colon adenocarcinoma (SW480), and melanoma (518A2) cell lines provided evidence for the high biological potential of the neutral and cationic iridium(III) complexes. Neutral iridium(III) complex 5 proved to be the most active, with IC50 values up to about 0.1 μM , representing activities of up to one order of magnitude higher than cisplatin. Using 8505C cells, apoptosis was shown to be the main mechanism through which complex 5 exerts its tumoricidal action. The described iridium(III) complexes represent potential leads in the search for novel metal‐based anticancer agents. 相似文献
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Contact models based on experimental characterization of irregular shaped,micrometer-sized particles
The goal of this study is to investigate experimentally the mechanical contact properties of fine particles ( \(<\) 120 \(\upmu \) m) using of a novel experimental setup. On the basis of deformation curves from compression tests, particle behaviour under mechanical stress can be approximated with theoretical contact models. Models examined in this study include Walton and Braun, Tomas and Antonyuk, Zener and Thornton. Influence of climatic conditions on particle behaviour as well as hardening effects related to cyclic loading were also considered. Maltodextrin was used as a model substance for primary particles, while irregular shaped titanium dioxide granules were used to study the behaviour of agglomerates. In both cases, results are in good agreement with the established theories. 相似文献
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Frank Schulze Anke Dienelt Sven Geissler Paul Zaslansky Janosch Schoon Katja Henzler Peter Guttmann Azza Gramoun Lindsey A. Crowe Lionel Maurizi Jean‐Paul Vallée Heinrich Hofmann Georg N. Duda Andrea Ode 《Small (Weinheim an der Bergstrasse, Germany)》2014,10(21):4340-4351
Mesenchymal stromal cells (MSCs) are promising candidates in regenerative cell‐therapies. However, optimizing their number and route of delivery remains a critical issue, which can be addressed by monitoring the MSCs’ bio‐distribution in vivo using super‐paramagnetic iron‐oxide nanoparticles (SPIONs). In this study, amino‐polyvinyl alcohol coated (A‐PVA) SPIONs are introduced for cell‐labeling and visualization by magnetic resonance imaging (MRI) of human MSCs. Size and surface charge of A‐PVA‐SPIONs differ depending on their solvent. Under MSC‐labeling conditions, A‐PVA‐SPIONs have a hydrodynamic diameter of 42 ± 2 nm and a negative Zeta potential of 25 ± 5 mV, which enable efficient internalization by MSCs without the need to use transfection agents. Transmission X‐ray microscopy localizes A‐PVA‐SPIONs in intracellular vesicles and as cytosolic single particles. After identifying non‐interfering cell‐assays and determining the delivered and cellular dose, in addition to the administered dose, A‐PVA‐SPIONs are found to be non‐toxic to MSCs and non‐destructive towards their multi‐lineage differentiation potential. Surprisingly, MSC migration is increased. In MRI, A‐PVA‐SPION‐labeled MSCs are successfully visualized in vitro and in vivo. In conclusion, A‐PVA‐SPIONs have no unfavorable influences on MSCs, although it becomes evident how sensitive their functional behavior is towards SPION‐labeling. And A‐PVA‐SPIONs allow MSC‐monitoring in vivo. 相似文献
130.
Fatigue crack growth behavior was studied for a Zr58.5Cu15.6Ni12.8Al10.3Nb2.8 bulk metallic glass in ambient air, demonstrating a fatigue threshold of ΔKTH = 1.4 MPa√m and a Paris law exponent of 1.7. A nearly stress intensity-independent crack growth regime occurred at 2.5 × 10?8 m cycle–1, suggesting an environmental influence of ambient air on the fatigue crack growth, as has been observed for Zr–Ti–Ni–Cu–Be bulk metallic glasses. However, this environmental fatigue effect was shifted to 25× higher growth rates due to the different chemistry. 相似文献