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781.
W. B. Dou Edward K. N. Yung 《Journal of Infrared, Millimeter and Terahertz Waves》2000,21(6):1001-1017
The scattering field of a ferrite post and a cylindrical ferrite post containing conducting post illuminated by a plane wave is analyzed. The special interest is the scattering property of the ferrite posts, which is resonating at certain modes such as TM11 mode. We hope to know the speciality it shows and find its applications. It is found that the scattering field pattern of a resonating ferrite post is similar to the rotation of the scattering field pattern of a dielectric cylindrical post, which has the same dimension as ferrite. The scattering properties of the ferrite may give us some inspirations to explore its applications in microwave components. This property is utilized to explain the mechanism of the operation of the circulators. It also may be used in microstrip patch antenna, coupler and filter to control their properties. Other applications may be possible too. Some calculation results are presented. 相似文献
782.
Scaling predictions for bottle‐brush polymers with a rigid backbone and flexible side chains under good solvent conditions are discussed and their validity is assessed by a comparison with Monte Carlo simulations of a simple lattice model. It is shown that typically only a rather weak stretching of the side chains is realized, and then the scaling predictions are not applicable. Also two‐component bottle brush polymers are considered, where two types (A,B) of side chains are grafted, assuming that monomers of different kind repel each other. In this case, variable solvent quality is allowed. Theories predict “Janus cylinder”‐type phase separation along the backbone in this case. The Monte Carlo simulations, using the pruned‐enriched Rosenbluth method (PERM) give evidence that the phase separation between an A‐rich part of the cylindrical molecule and a B‐rich part can only occur locally. The correlation length of this microphase separation can be controlled by the solvent quality. This lack of a phase transition is interpreted by an analogy with models for ferromagnets in one space dimension.
783.
Hung‐Te Chang Kuo‐Chen Chiang Fung Fuh Wong Chun‐Sheng Huang Yang‐Ming Liao Wen‐Fa Kuo Shaw‐Bing Won Mou‐Yung Yeh 《Heteroatom Chemistry》2007,18(4):438-442
The synthesis of potential fluorescent active 4‐(5‐aryl‐1,3,4‐oxadiazol‐2‐yl)phenylhydrazine derivatives was accomplished in three steps. The key step was the dehydration cyclization of 1,2‐diacylhydrazines to form the 1,3,4‐oxadiazole ring by use of acetic anhydride/perchloric acid mixture as the dehydrating agent. The sydnone moiety served as the masked hydrazines, which could be demasked by HCl for further application. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:438–442, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20318 相似文献
784.
Harvesting salinity gradient energy, also known as “osmotic energy” or “blue energy”, generated from the free energy mixing of seawater and fresh river water provides a renewable and sustainable alternative for circumventing the recent upsurge in global energy consumption. The osmotic pressure resulting from mixing water streams with different salinities can be converted into electrical energy driven by a potential difference or ionic gradients. Reversed-electrodialysis (RED) has become more prominent among the conventional membrane-based separation methodologies due to its higher energy efficiency and lesser susceptibility to membrane fouling than pressure-retarded osmosis (PRO). However, the ion-exchange membranes used for RED systems often encounter limitations while adapting to a real-world system due to their limited pore sizes and internal resistance. The worldwide demand for clean energy production has reinvigorated the interest in salinity gradient energy conversion. In addition to the large energy conversion devices, the miniaturized devices used for powering a portable or wearable micro-device have attracted much attention. This review provides insights into developing miniaturized salinity gradient energy harvesting devices and recent advances in the membranes designed for optimized osmotic power extraction. Furthermore, we present various applications utilizing the salinity gradient energy conversion. 相似文献
785.
The input impedance and the antenna gain of the spherical helical antenna are obtained theoretically and experimentally. Results indicate the better performance of the 3-turn antenna over the 7-turn one in terms of the impedance bandwidth and the stability of the antenna gain. The theoretical current distribution is also obtained and its salient characteristics are discussed 相似文献
786.
Hsiu-Fen Chou A. Ching-Song Yang E. Cheng-Jye Liu Hsiu-Hsiang Pong Ming-Chi Liaw Ten-Sen Chao Ya-Chin King Huey-Liang Hwang Ching-Hsiang Hsu C. 《Electron Devices, IEEE Transactions on》2001,48(7):1386-1393
In this paper a recently proposed bidirectional tunneling program/erase (P/E) NOR-type (BiNOR) flash memory is extensively investigated. With the designated localized p-well structure, uniform Fowler-Nordheim (FN) tunneling is first fulfilled for both program and erase operations in NOR-type array architecture to facilitate low power applications. The BiNOR flash memory guarantees excellent tunnel oxide reliability and is provided with fast random access capability. Furthermore, a three-dimensional (3D) current path in addition to the conventional two-dimensional (2D) conduction is proven to improve the read performance. The BiNOR flash memory is thus promising for low-power, high-speed, and high-reliability nonvolatile memory applications 相似文献
787.
Jyh‐Horng Wen Kuo‐Gen Hsu Jet‐Chau Wen Yi‐Show Chen 《International Journal of Communication Systems》2001,14(5):497-511
Power assignment schemes are man‐made methods to enhance the capture effect of radio communications. In a previous study, Wen and Yang investigated the combined capture effect of the fixed power assignment scheme, Rayleigh fading, and near–far effect on the performance of packet radios. The performance analysis was limited to an infinite population environment. This assumption is reasonable for a conventional packet radio system with a vast service area. However, for a cellular mobile system, a finite population model should be used. In this paper, we analyse the combined natural and man‐made capture effect on the performance of a cellular system with finite population in each cell. A random power assignment scheme is adopted to produce the man‐made capture. The system throughput and delay are carried out by a Markov model. Some numerical calculations are used to demonstrate the degree of performance improvement. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
788.
789.
The use of capillary column gas chromatography and gas chromatography/mass spectrometry for the analysis of a series of standard solutions (0.1 to 10 μg/ml) of 2,4,6-trinitrotoluene (TNT) and eight other nitroaromatic components was evaluated. The techniques included gas chromatography with electron capture detection (GC/ECD), full scan and selected ion monitoring gas chromatography/mass spectrometry with electron impact ionization (EI/FS and EI/SIM), full scan and selected ion monitoring gas chromatography/mass spectrometry with positive ion chemical ionization using methane reagent gas (PICI/FS and PICI/SIM), and full scan and selected ion monitoring gas chromatography/mass spectrometry with negative ion chemical ionization using methane reagent gas (NICI/FS and NICI/SIM). The performance of the techniques was comapared by determining the linear response range, precision, and detection limits of the analyses. 相似文献
790.
Physical analysis on improving the recovery accuracy of the Earth’s gravity field by a combination of satellite observations in along-track and cross-track directions 总被引:1,自引:0,他引:1 下载免费PDF全文
The physical investigations on the accuracy improvement to the measurement of the Earth's gravity field recovery are carried out based on the next-generation Pendulum-A/B out-of-plane twin-satellite formation in this paper. Firstly, the Earth's gravity field complete up to degree and order 100 is, respectively, recovered by the collinear and pendulum satellite formations using the orbital parameters of the satellite and the matching accuracies of key payloads from the twin GRACE satellites. The research results show that the accuracy of the Earth's gravity field model from the Pendulum-A/B satellite formation is about two times higher than from the collinear satellite formation, and the further improvement of the determination accuracy of the Earth's gravity field model is feasible by the next-generation Pendulum-A/B out-of-plane twin-satellite formation. Secondly, the Earth's gravity field from Pendulum-A/B complete up to degree and order 100 is accurately recovered based on the orbital parameters of the satellite (e.g., an orbital altitude of 400 km, an intersatellite range of 100 km, an orbital inclination of 89° and an orbital eccentricity of 0.001), the matching accuracies of space- borne instruments (e.g. 10-6 m in the intersatellite range, 10-3 m in the orbital position, 10-6 m/s in orbital velocity, and 10-11 m/s2 in non-conservative force), an observation time of 30 days and a sampling interval of 10 s. The measurement accuracy of the Earth's gravity field from the next-generation Pendulum-A/B out-of-plane twin-satellite formation is full of promise for being improved by about l0 times compared with that from the current GRACE satellite formation. Finally, the physical requirements for the next-generation Pendulum-A/B out-of-plane twin-satellite formation are analyzed, and it is proposed that the satellite orbital altitude be preferably designed to be close to 400±50 km and the matching precision of key sensors from the Pendulum-A/B mission be about one order of magnitude higher tha 相似文献