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901.
Jens Kling Wook Jo Robert Dittmer Silke Schaab Hans‐Joachim Kleebe 《Journal of the American Ceramic Society》2013,96(10):3312-3324
Lead‐free piezoelectric (1 – x – y)(Bi1/2Na1/2)TiO3–xBaTiO3–y(K0.5Na0.5)NbO3 (BNT–BT–KNN) ceramics were examined in situ under increasing temperature in the transmission electron microscope. Changing superstructure reflections indicate a transition from rhombohedral to tetragonal to cubic phase with broad coexistence regions. The additional evolution of the microstructure in combination with dielectric measurements leads to a model of two relaxor‐type phase evolutions with temperature. 相似文献
902.
Akbar Arabhosseini Sudhakar Padhye Willem Huisman Anton van Boxtel Joachim M��ller 《Food and Bioprocess Technology》2011,4(7):1281-1287
The effect of drying conditions on the color of tarragon (Artemisia dracunculus L.) leaves was studied. Tarragon leaves were dried at temperatures of 40 to 90 °C with a constant airflow of 0.6 m/s. The
samples were collected at 7%, 10%, 20%, and 30% moisture content wet basis for evaluation of the color change. The color parameters
of fresh and dried leaves were measured by a colorimeter. The individual parameters of L*a*b* and L*C*h° color systems were evaluated and h° proved to be the best parameter to monitor color change. The smallest change of the color parameters was observed at 40 °C,
in which temperature was low, and also at 90 °C, when drying time was short. The biggest change occurred at the temperatures
of 50 to 70 °C. Most of the color change happened before the material reaches 35% moisture content. The combination of drying
time and temperature defines the change of color. 相似文献
903.
Lorenzo Vincenzi Sho Suzuki David Outcalt Joachim Heberlein 《Journal of Thermal Spray Technology》2010,19(4):713-722
In order to identify means to improve plasma spray consistency, various modifications to the design of a commercial plasma
torch nozzle have been investigated. The modifications consist of preparing anode inserts with grooves in the axial direction
(spline insert), and introducing a fraction of the plasma gas through a ring of micro-nozzles surrounding the anode nozzle
(micro-jet ring). Different designs for each modification have been investigated, and these modifications have also been paired
with a modified upstream gas injector. For each of the modified designs, a wide range of characteristics have been measured
for the arc, the plasma jet, the in-flight particles, and the coating. The results show that most nozzle modifications lead
to higher particle temperatures and velocities. The plasma jet is significantly elongated by using some of the modified nozzles,
and the cold gas entrainment somewhat reduced. Each of the nozzle modifications can be easily implemented offering an economical
way to enhance process reliability. 相似文献
904.
Tensile properties of high Mn austenitic Fe‐26.5Mn‐3.6Al‐2.2Si‐0.38C‐0.005B (HM1) and Fe‐18.9Mn‐0.62C‐0.02Ti‐0.005B (HM2, in mass%) steels after different solution treatments have been investigated. The results show that the solution treatment has a significant influence on microstructure and mechanical properties of the investigated steels. By appropriate solution treatment the product of tensile strength (Rm) and total elongation (A50) of the hot rolled steel can be improved from ? 40000‐50000 MPa% to ? 55000‐65000 MPa% depending on the steel chemical composition. A solution treatment with a very high temperature, e.g. at 1100 °C for the Fe‐18.9Mn‐0.62C‐0.02Ti‐0.005B steel, results in a significant increase in the ?‐martensite fraction during quenching. This deteriorates the ductility of the steel. A solution treatment at low temperature in the austenitic range, e.g. at 700 °C for the Fe‐18.9Mn‐0.62C‐0.02Ti‐0.005B steel, results in a decrease in the grain size of the steel. This suppresses the ?‐martensite transformation during cooling. EBSD measurements revealed the mechanisms contributing to the overall plasticity of the investigated steels on the microscale. The plasticity of the 26.5Mn‐3.6Al‐2.2Si‐0.38C‐0.005B steel is produced mainly by TWIP mechanism under the examined experimental conditions, whereas for the Fe‐18.9Mn‐0.62C‐0.02Ti‐0.005B steel TWIP and TRIP mechanisms occur with different degrees depending on the test temperature of the tensile test. 相似文献
905.
Orthogonal frequency division multiplexing (OFDM) systems suffer significantly from inter-carrier interference (ICI) caused
by double selective channels. In this paper, we develop a two-stage hybrid channel estimation and ICI cancellation structure
for OFDM. The double selective channels are approximated by an improved Basis Expansion Model (BEM), which is more accurate
than the conventional BEM when the normalized Doppler frequency is smaller than one. Based on this improved model, a new ICI
cancellation scheme is proposed to reduce ICI impact. Simulation results show that the framework performs well.
相似文献
Joachim SpeidelEmail: |
906.
907.
In this work, a 2D aero‐servo‐elastic model of an airfoil section with 3 degrees of freedom (DOF) based on the 2D CFD solver EllipSys2D to calculate the aerodynamic forces is utilized to calculate the load reduction potential of an airfoil equipped with an adaptive trailing edge flap (ATEF) and subjected to a turbulent inflow signal. The employed airfoil model corresponds to a successfully tested prototype airfoil where piezoelectric actuators were used for the flapping. In the present investigation two possible control methods for the flap are compared in their ability to reduce the fluctuating normal forces on the airfoil due to a 4 s turbulent inflow signal and the best location of the measurement point for the respective control input is determined. While Control 1 uses the measurements of a Pitot tube mounted in front of the leading edge (LE) as input, Control 2 uses the pressure difference between the pressure and suction side of the airfoil measured at a certain chord position. Control 1 achieves its maximum load reduction of RStd(Fy) = 76.7% for the shortest Pitot tube of the test, i.e. a Pitot tube with a length of 0.05% of the chord length. Control 2 shows the highest load reduction of RStd(Fy) = 77.7% when the pressure difference is measured at a chord position of approximately 15%. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
908.
Product design is a cutting-edge area of research. Over the last few years, many papers have been presented dealing with product design. The review focuses on processing of crystalline solids with a particular filed of application in mind and shows how crystallization can be used as tool to generate materials with particular properties and how to tailor these properties by crystallization. The fact that crystallization is a tool for product design will be highlighted by 4 selected examples, dealing with roughness and shelf life of fertilizer granules (case 1 and 2), with micro container as carrier system and, finally, with an alternative tablet forming technique for heat sensitive materials. 相似文献
909.
The influence of the cathodic process on the interpretation of electrochemical noise signals arising from pitting corrosion of stainless steels 总被引:1,自引:0,他引:1
The use of electrochemical noise (EN) measurements for the investigation and monitoring of corrosion has allowed many interesting advances in the corrosion science in recent years. A special advantage of EN measurements includes the possibility to detect and study the early stages of localized corrosion. Nevertheless, the understanding of the electrochemical information included in the EN signal is actually very limited. The role of the cathodic process on the EN signals remains uncertain and has not been sufficiently investigated to date. Thus, an accurate understanding of the influence of the cathodic process on the EN signal is still lacking. On the basis of different kinetics of the oxygen reduction it was established that the anodic amplitude of transients arising from pitting corrosion on stainless steel can be decreased by the corresponding electron consumption of the cathodic process. Therefore, the stronger the electron consumption, the weaker the anodic amplitude of the EN signal becomes. EN signals arising from pitting corrosion on stainless steel can be measured because the cathodic process is inhibited by the passive layer. This was confirmed by means of EN measurements under cathodic polarisation. Since the cathodic process plays a decisive role on the form of transients arising from pitting corrosion, its influence must be considered in the evaluation and interpretation of the EN signals. 相似文献
910.
Maksym Seredyuk Ana B. Gaspar Vadim Ksenofontov Yury Galyametdinov Joachim Kusz Philipp Gütlich 《Advanced functional materials》2008,18(14):2089-2101
Reaction of the ligand 2,2,2‐tris(2‐aza‐3‐((5‐akloxy)(6‐methyl)(2‐pyridyl))prop‐2‐enyl)ethane (Cn‐tameMe) with Fe(X)2 · sH2O salts afforded a series of spin crossover metallomesogens with general formula [Fe(Cn‐tame)](X)2 · sH2O (s ≥ 0), with n = 6, 10, 12, 14, 16, 17, 18, or 20 and X = ClO4? or BF4?. Single crystal X‐ray measurements have been performed on the [Fe(C6‐tameMe)](ClO4)2 ( C 6 ‐1 ) derivative at 100 K. The complex C 6 ‐1 crystallizes in the triclinic system and adopts the Pbca space group. The iron(II) ion is in a distorted octahedral environment shaped by three imine and three pyridine nitrogen atoms of the Cn‐tameMe ligand. The average Fe–Nim and Fe–Npy bond distance is 1.918(2) Å and 2.084(2) Å, respectively, which are characteristic for the Fe(II) ion in the LS state. Neighbor molecules are packed in a head‐to‐head fashion forming a layered microsegregated structure. Ionic layer is composed of cationic spin crossover head‐groups and perchlorate anions, whereas alkyl tails are arranged into a non‐polar hydrocarbon layer. The complex [Fe(C18‐tameMe)](ClO4)2 ( C 18 ‐1 ) and the series [Fe(Cn‐tameMe)](BF4)2 (n = 10, 12, 14, 16, 17, 18, 20) ( C n ‐2 ) series show thermally driven spin crossover and mesomorphism above 300 K. The thermotropic behavior of compounds C n ‐2 depends on the chain length defined by n. A common structural feature among all homologues of the series is a similar layered structure and adoption on melting of a smectic mesophase at ca. 350–375 K. Formation of the mesophase is due to the melting of the alkyl chains rather than a rearrangement of the ionic bilayers composed of polar SCO cations and BF4? or ClO4? anions. This gives rise to a mesophase with molten alkyl chains but with restricted movement through the ionic layer. Compounds C n ‐2 show thermochromic properties, they are dark violet in the LS state (T < 275 K, Cr) and become red in the HS state (T > 275 K, Cr, SX). These bi‐functional materials combine spin state change and mesomorphic behavior in a narrow interval of temperatures, 300–375 K. 相似文献