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971.
Jung Yong Kim In Jae Chung Changhee Lee Young Chul Kim Jai Kyeong Kim Jae-Woong Yu 《Current Applied Physics》2005,5(6):615-618
N,N′-diphenylbutyl-3,4,9,10-perylenebiscarboximide (PTCDI-C4Ph) were characterized by optical and electrochemical methods. A device with an ITO/PTCDI-C4Ph (≈2 μm)/Al structure was fabricated to measure mobility by time-of-flight techniques. This vacuum deposited organic layer was an amorphous state. Electrons were observed faster than holes. The electron and hole mobilities were 1.8 × 10−4 cm2/V s and 1.1 × 10−4 cm2/V s under the electric field of 500 (V/cm)1/2, respectively. This result shows that this organic compound is a good candidate for an n-type conduction. 相似文献
972.
Hydrometeor classification system using dual-polarization radar measurements: model improvements and in situ verification 总被引:2,自引:0,他引:2
Lim S. Chandrasekar V. Bringi V.N. 《Geoscience and Remote Sensing, IEEE Transactions on》2005,43(4):792-801
A hydrometeor classification system based on a fuzzy logic technique using dual-polarization radar measurements of precipitation is presented. In this study, five dual-polarization radar measurements (namely horizontal reflectivity, differential reflectivity, specific differential phase, correlation coefficient, and linear depolarization ratio) and altitude relating to environmental melting layer are used as input variables of the system. The hydrometeor classification system chooses one of nine different hydrometeor categories as output. The system presented in this paper is a further development of an existing hydrometeor classification system model developed at Colorado State University (CSU). The hydrometeor classification system is evaluated by comparing inferred results from the CSU CHILL Facility dual-polarization radar measurements with the in situ sample data collected by the T-28 aircraft during the Severe Thunderstorm Electrification and Precipitation Study. 相似文献
973.
In previous work, unequal error-protection techniques have been applied to improve the throughput of a wireless communication system in which a transmission is received by several radios with different capabilities. For instance, these capabilities may correspond to differences in path loss, fading, or interference. By taking advantage of the broadcast nature of the channel, additional messages for the more-capable receivers can be included on transmissions to the less-capable receivers at very little cost (in terms of required energy at the transmitter or error probabilities at the receivers). This technique has been termed simulcasting or multicast signaling. In this paper, we consider the use of these techniques in an ad hoc network. These techniques impact the link throughput, end-to-end throughput, and network connectivity. We investigate how the choice of parameters for the simulcasting technique affects these network performance metrics. The results indicate that a properly chosen simulcasting technique can improve the link and end-to-end throughput in wireless ad hoc networks with only a slight degradation in other metrics, such as network connectivity. 相似文献
974.
Junha Kim Jinhwan Jung Kwanghee Nam 《Industrial Electronics, IEEE Transactions on》2004,51(2):312-320
An integrated starter/alternator (ISA) is normally designed to have high pole structure (10-14 poles) for high starting torque. However, its back electromotive force (EMF) at the peak revolutions per minute should be less than its battery voltage for the power flow control. For example, the back-EMF of a 12-pole ISA should be 42 V at 6000 r/min. These types of conflicting requirements lead to a nonclassical motor design that has extremely large field-weakening range (8:1/spl sim/10:1). In this paper, we are considering the use of an induction machine instead of a permanent synchronous machine. As an idea for solving the voltage limit problem, two inverters are utilized with an objective of sharing the required voltage. The secondary inverter only takes care of the reactive voltage component that grows very fast in high-speed operation. Therefore, an extra voltage source is not required for the secondary inverter. Only a capacitor bank suffices for the secondary inverter. 相似文献
975.
A compact Ids model with physical drain-conductance (gds) modeling for deep-submicron MOSFETs is formulated based on first-principle momentum-/energy-balance equations, which simultaneously includes the hot-electron and thermoelectric effects in a unified compact form with two fitting parameters and one-step extraction. The model has been verified with 0.18-μm experimental data with good gds prediction. 相似文献
976.
This is the first report of an analytical plasma in a polymer (polydimethylsiloxane, PDMS) microchip. The plasma channel has dimensions 2 mm diameter × 50 mm long, is operated at atmospheric pressure in Ar, 27.12 MHz and 70 W, and is viewed axially through a purged fiber optic cable. CF4 gas at 0.1% in argon yields mainly C2 emission bands. This PDMS microchip is manufactured easily, inexpensive, and more tolerant to fluorocarbons than microchip plasmas in silica. Based on these initial results, this PDMS microchip plasma could become useful as a sensor for the fluorocarbon gases emitted in semiconductor process or as a gas chromatography (GC) detector for potential application. 相似文献
977.
Micromachining is gaining popularity due to recent advancements in Micro Electro Mechanical Systems. Using conventional micromachining,
it is relatively difficult to produce moving components in the order of microns. In this study, an attempt is made to fabricate
microstructures using a combination of turning and electrodischarge machining (EDM). Several sets of experiments have been
performed to study the characteristics of the hybrid machining process. From the experiments, it has been observed that a
higher form of accuracy could be obtained by integrating the on-machine fabrication of the tool and by subsequently using
the same tool for EDM. The main cause of the form error is due to the deflection of the shaft during turning. Hence, an attempt
is made to observe the deflection of the shaft using a deflection sensor. The influence of micro-EDM parameters such as feed
rate, discharge circuits, and gap control parameters on material removal rate and tool wear is also discussed in this study. 相似文献
978.
S.I. Jung J.J. Yoon H.J. Park Y.M. Park M.H. Jeon J.Y. Leem C.M. Lee E.T. Cho J.I. Lee J.S. Kim J.S. Son J.S. Kim D.Y. Lee I.K. Han 《Physica E: Low-dimensional Systems and Nanostructures》2005,26(1-4):100
We investigate the effects of a thin AlAs layer with different position and thickness on the optical properties of InAs quantum dots (QDs) by using transmission electron microscopy and photoluminescence (PL). The energy level shift of InAs QD samples is observed by introducing the thin AlAs layer without any significant loss of the QD qualities. The emission peak from InAs QDs directly grown on the 4 monolayer (ML) AlAs layer is blueshifted from that of reference sample by 219 meV with a little increase in FWHM from 42–47 meV for ground state. In contrast, InAs QDs grown under the 4 ML AlAs layer have PL peak a little redshifted to lower energy by 17 meV. This result is related to the interdiffusion of Al atom at the InAs QDs caused by the annealing effect during growing of InAs QDs on AlAs layer. 相似文献
979.
Jong-Seok Kim Sang-Woo Lee Kyu-Dong Jung Woon-Bae Kim Sung-Hoon Choa Byeong-Kwon Ju 《Microelectronics Reliability》2008,48(6):948-952
A micro-machined gyro chip of gyroscope is normally packaged in specific vacuum level to get the specific quality factor(Q-factor). If the Q-factor is too high, frequency tuning and the approximate matching between driving and sensing comb structure become difficult, and if the Q-factor is too low, its sensitivity decreases. The optimum Q-factor of our gyro chip design is 4000 range. To get this range, we measured the drive mode Q-factor as vacuum level of our gyro chip and we found that the vacuum level of the desired Q-factor 4000 is in the range of 740 mTorr. Based on this data, we fabricate the wafer level package gyro chip of the desired Q-factor by controlled the basic pressure of package bonding chamber just prior to the bonding process. After wafer level package process, we measured Q-factor of whole samples. Among 804 samples, 502 packaged gyro chips are worked and the Q-factor of 67% samples is between 3500 and 4500 range. 相似文献
980.
The optical properties of zirconia films doped with rhodamine 6G and oxazine 725 by the sol-gel process were investigated using spectroscopic ellipsometry (SE). Accurate refractive index n and the extinction coefficient k were determined using a three-oscillator classical Lorentz model in the wavelength range of 300-800 nm. The derived refractive index of dye-doped films exhibited anomalous dispersion in the absorption region. Wavelength tunable output lasing action yellow and near-infrared wavelength region was achieved by DFB configuration using zirconia films doped with R6G and oxazine 725. 相似文献