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161.
Evaluation of service life design models on concrete structures exposed to marine environment 总被引:2,自引:0,他引:2
Irina Stipanovic Oslakovic Dubravka Bjegovic Dunja Mikulic 《Materials and Structures》2010,43(10):1397-1412
Durability of reinforced concrete is primarily influenced by the penetration of aggressive substances into concrete, which
are degrading concrete and reinforcement. For structures in marine environment chlorides are the most critical environmental
load, which are causing serious corrosion damages. Data collected during the survey of the Krk Bridge, a large reinforced
concrete arch bridge structure located on the Adriatic coast, is used as documented reference in this research. The structure
has been exposed to the marine environment for over 25 years. Based on collected materials data and the exposure conditions,
the service life of this structure is estimated using three currently available prediction models, two deterministic models,
the North American Life-365 model and the Croatian CHLODIF model, and the DuraCrete probabilistic method. All these models are based on the chloride diffusion process, but with different detailing of the model
parameters. The conclusion is an evaluation of the service life predictive ability of each of these three service life models. 相似文献
162.
Nair RR Ren W Jalil R Riaz I Kravets VG Britnell L Blake P Schedin F Mayorov AS Yuan S Katsnelson MI Cheng HM Strupinski W Bulusheva LG Okotrub AV Grigorieva IV Grigorenko AN Novoselov KS Geim AK 《Small (Weinheim an der Bergstrasse, Germany)》2010,6(24):2877-2884
A stoichiometric derivative of graphene with a fluorine atom attached to each carbon is reported. Raman, optical, structural, micromechanical, and transport studies show that the material is qualitatively different from the known graphene-based nonstoichiometric derivatives. Fluorographene is a high-quality insulator (resistivity >10(12) Ω) with an optical gap of 3 eV. It inherits the mechanical strength of graphene, exhibiting a Young's modulus of 100 N m(-1) and sustaining strains of 15%. Fluorographene is inert and stable up to 400 °C even in air, similar to Teflon. 相似文献
163.
Rahul R. Nair Wencai Ren Rashid Jalil Ibtsam Riaz Vasyl G. Kravets Liam Britnell Peter Blake Fredrik Schedin Alexander S. Mayorov Shengjun Yuan Mikhail I. Katsnelson Hui‐Ming Cheng Wlodek Strupinski Lyubov G. Bulusheva Alexander V. Okotrub Irina V. Grigorieva Alexander N. Grigorenko Kostya S. Novoselov Andre K. Geim 《Small (Weinheim an der Bergstrasse, Germany)》2010,6(24):2773-2773
A stoichiometric derivative of graphene with a fluorine atom attached to each carbon is reported. Raman, optical, structural, micromechanical, and transport studies show that the material is qualitatively different from the known graphene‐based nonstoichiometric derivatives. Fluorographene is a high‐quality insulator (resistivity >1012 Ω) with an optical gap of 3 eV. It inherits the mechanical strength of graphene, exhibiting a Young’s modulus of 100 N m?1 and sustaining strains of 15%. Fluorographene is inert and stable up to 400 °C even in air, similar to Teflon. 相似文献
164.
Baruch Rosenstein Irina Shapiro Boris Y. Shapiro 《Journal of Low Temperature Physics》2013,173(5-6):289-302
There are indications that some high temperature unconventional superconductors have a “complex” d-wave order parameter (with an admixture of s-wave) leading to nonzero energy gap. Since the coherence length is short and the Fermi energy is relatively small the quasiclassical approach is inapplicable and the more complicated Bogoliubov-deGennes equations should be used to investigate the excitation spectrum of such a material in a magneric field. It turns out that equations for the chiral d-wave superconductor simplify considerably and is the basis for any superconductor of that type with a sufficiently large gap. The spectrum of core excitations of the Abrikosov vortex in an anisotropic 3D sample exhibits several features. Unlike in conventional and gapless superconductors the core has a single excitation mode of order energetic gap for each value of momentum along the field. This has a large impact on thermal transport and vortex dynamics. 相似文献
165.
Martin Halmann Aldo Steinfeld Michael Epstein Irina Vishnevetsky 《Mineral Processing and Extractive Metallurgy Review》2013,34(2):126-135
The current industrial production of aluminum from alumina is based on the electrochemical Hall-Héroult process, which has the drawbacks of high-greenhouse gas emissions, reaching up to 0.70 kg CO2-equiv/kg Al, and large energy consumption, about 0.055 GJ/kg Al. An alternative process is the carbothermic reduction of alumina. Thermodynamic equilibrium calculations and experiments by induction furnace heating indicated that this reaction could be achieved under atmospheric pressure only above 2200°C. Lower required reaction temperatures can be achieved by alumina reduction under vacuum. This was experimentally demonstrated under simulated concentrated solar illumination and by induction furnace heating. By decreasing the CO partial pressure from 3.5 mbar to 0.2 mbar, the temperature required for almost complete reactant consumption could be decreased from 1800°C to 1550°C. Deposits condensed on the relatively cold reactor walls contained up to 71 wt% of Al. Almost pure aluminum was observed as Al drops, while a gray powder contained 60–80% Al and a yellow-orange powder contained only Al4C3, Al-oxycarbides and Al2O3. 相似文献
166.
Park CC Kazakova I Kawabata T Spaid M Chien RL Wada HG Satomura S 《Analytical chemistry》2008,80(3):808-814
This report describes a method of controlling the sensitivity and reproducibility of a microchip-based immunoassay by using isotachophoresis to preconcentrate the antigen and antibody prior to binding. Gel electrophoresis separation is coupled to the preconcentration step to separate the immunocomplex products formed. The system employs a quartz-based LabChip that automates the metering, preconcentration, reaction, separation, and detection. The system also uses a handoff mechanism that switches the immunocomplex from the stacking mode to the separation mode. We show that the handoff timing affects the data quality and repeatability of the electropherograms, and we demonstrate an automatic handoff mechanism to precisely control the signal intensity and separation of peaks of interest. In so doing, the automatic handoff mechanism also improves the reproducibility of the assay. When applied to the homogeneous liquid-phase detection of alpha-fetoprotein, a common tumor marker, the system shows a greater than 200-fold stacking of specific analytes of interest. 相似文献
167.
Astakhova IK Samokhina E Babu BR Wengel J 《Chembiochem : a European journal of chemical biology》2012,13(10):1509-1519
We describe fluorescent oligonucleotide probes labeled with novel (phenylethynyl)pyrene dyes attached to locked nucleic acids. Furthermore, we prove the utility of these probes for the effective detection of single-nucleotide polymorphisms in natural nucleic acids. High-affinity hybridization of the probes and excellent fluorescence responses to single-base mismatches in DNA/RNA targets are demonstrated in model dual-probe and doubly labeled probe formats. This stimulated us to develop two diagnostic systems for the homogeneous detection of a drug-resistance-causing mutation in HIV-1 protease cDNA and RNA gene fragments. Target sequences were obtained by analysis of 200 clinical samples from patients currently receiving anti-HIV/AIDS combination therapy at the Russian Federal AIDS Center. Using these fluorescent oligonucleotides, we were able to detect the target mutation despite all the challenges of the natural targets, that is, the presence of additional mutations, neighboring sequence variation, and low target concentration, which typically reduce binding and effectiveness of sensing by fluorescent oligonucleotides. 相似文献
168.
Thomas Ingram Sandra Storm Philipp Glembin Stephan Bendt Désirée Huber Tanja Mehling Prof. Dr.‐Ing. Irina Smirnova 《化学,工程师,技术》2012,84(6):840-848
Aqueous nonionic surfactant solutions split into two phases if the temperature is increased beyond a certain temperature, the so‐called cloud point temperature. Presently many different types of nonionic surfactants are produced commercially, out of these numerous have been considered as potential solvent for the cloud point extraction. In this work the crucial thermophysical properties of nonionic surfactants are investigated to determine the potential of surfactant systems for extraction processes. Phase equilibria of the binary system Triton X‐114/water and the ternary system Triton X‐114/water/phenol were measured. Based on these data the cloud point extraction was implemented in a continuous stirred extraction column. It was found, that increasing temperature within the column reduces the loss of surfactant and leads to an increasing enrichment factor. This work demonstrates that surfactant/water systems represent a suitable alternative to conventional solvents and can effectively be processed in continuous extraction columns. 相似文献
169.
Irina Bacosca Elena Hamciuc Mariana Cristea Gabriela Lisa Maria Bruma 《应用聚合物科学杂志》2012,124(3):1956-1966
A series of poly(ether imide)s containing functional cyano groups has been prepared by polycondensation reaction of 2,6‐bis(m‐aminophenoxy)benzonitrile with different bis(ether dianhydride)s, such as 2,2‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]isopropane dianhydride, 2,2‐bis[4‐(3,4‐dicarboxyphenoxy)‐phenyl]hexafluoroisopropane dianhydride, 1,1‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]cyclohexane dianhydride, and 3,3‐bis[4‐(3,4‐dicarboxyphenoxy) phenyl]phthalide dianhydride. The polymers were soluble in polar aprotic solvents and even in less polar solvents and were processed into thin films by casting their solutions. The properties of the polymers, particularly the crosslinking of macromolecular chains through cyano groups, were studied by using dynamic mechanical analysis (DMA), thermal stability, glass transition, and solubility measurements. Also, the molecular relaxations were evidenced by DMA and dielectric spectroscopy. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
170.
Yulia?A.?Piskun Irina?V.?Vasilenko Ludmila?V.?Gaponik Sergei?V.?KostjukEmail author 《Polymer Bulletin》2012,68(6):1501-1513
The activated anionic ring-opening polymerization of ε-caprolactam initiated by 0.35 mol% of combined initiator, i.e., equimolar
mixture of magnesium di(ε-caprolactamate) (CL2Mg) with magnesium halides (MgCl2, MgBr2, and MgI2) as well as of ε-caprolactam magnesium bromide (CLMgBr) in the presence of 0.35 mol% of N-acetyl-ε-caprolactam as an activator has been investigated in the temperature range 140–200 °C. It was found that the reaction
rate increased while the apparent activation energy decreased in the following series: CL2Mg/MgCl2 < CL2Mg/MgBr2 ~ CLMgBr < CL2Mg/MgI2. In addition, the poly(ε-caprolactam)s prepared with CL2Mg/MgX2 (MgX2 = MgCl2, MgBr2, and MgI2) are characterized by slightly higher thermal stability than polymers obtained with CLMgBr as initiator. These observations
were explained in terms of the coordination of Lewis acids (MgX2, where X = Cl, Br, and I) with imide carbonyl of N-acyllactam end groups leading to the increase of their reactivity and stability. 相似文献