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排序方式: 共有172条查询结果,搜索用时 343 毫秒
31.
Baoyin Han Sai-Anand Gopalan Kwang-Don Lee Byoung-Ho Kang Sang-Won Lee Jae-Sung Lee Dae-Hyuk Kwon Seung-Ha Lee Shin-Won Kang 《Current Applied Physics》2014,14(11):1443-1450
In this study, we explored the ability of a preheated solvent (methanol) to induce characteristic changes at the organic active layer/metal interface, thereby improving the performance of fabricated organic photovoltaic (OPV) cells composed of poly(3-hexylthiopene) (P3HT) and a [6,6]-phenyl-C71-butyric acid methyl ester (PCBM) photoactive blend. Our results demonstrate that exposure to methanol (at room temperature, or preheated at 45 °C or 65 °C) improves the performance of the fabricated OPV cells. After preheated methanol exposure, the P3HT:PCBM thin films were tested for crystallinity, morphology, mobility, and photovoltaic characteristics. Our results revealed that use of the preheated solvent on the organic active layer significantly influences the micro/nano scale morphology and phase segregation of the P3HT:PCBM thin films, as well as the charge carrier mobility. It is hypothesized that the side chain ordering of P3HT and redistribution of PCBM could be results of the modified active layer. Consequently, OPV cells modified with the methanol preheated at 65 °C exhibited a power conversion efficiency (PCE) of 3.36%, with open-circuit voltage of 0.59 V, short-circuit current density of 13.83 mA/cm2, and fill-factor of 0.41. In contrast, the unmodified P3HT:PCBM thin film (without methanol exposure) showed a PCE of only 2.13%. 相似文献
32.
Jeng S.J. Jagannathan B. Rieh J.-S. Johnson J. Schonenberg K.T. Greenberg D. Stricker A. Chen H. Khater M. Ahlgren D. Freeman G. Stein K. Subbanna S. 《Electron Device Letters, IEEE》2001,22(11):542-544
A record 210-GHz fT SiGe heterojunction bipolar transistor at a collector current density of 6-9 mA/μm2 is fabricated with a new nonself-aligned (NSA) structure based on 0.18 μm technology. This NSA structure has a low-complexity emitter and extrinsic base process which reduces overall thermal cycle and minimizes transient enhanced diffusion. A low-power performance has been achieved which requires only 1 mA collector current to reach 200-GHz fT. The performance is a result of narrow base width and reduced parasitics in the device. Detailed comparison is made to a 120-GHz self-aligned production device 相似文献
33.
The multi-hop multi-rate wavelength division multiplexing ring 总被引:1,自引:0,他引:1
Cerutti I. Fumagalli A. Tacca M. Lardies A. Jagannathan R. 《Lightwave Technology, Journal of》2000,18(12):1649-1656
Transparency of the optical layer offers the possibility to design a network that operates at varying transmission bit rates. While variable bit rate interfaces are being tested and will soon provide the possibility to optimally select the transmission rate for each optical channel, the potential advantages of relying upon multiple transmission rates in the optical network have yet to be fully explored. In this paper, we define the concept of multi-hop and multi-rate (M&M for short) network in which the tributary signal is transmitted over a concatenation of optical channels, with each optical channel operating at its own transmission rate. The optimal rate of each optical channel is determined by a number of factors including the end node's interface, amount of multiplexed traffic and cost of the network components. The potential advantages provided by the M&M network when compared to first generation optical networks (i.e., SONET/SDH), to single- and multi-hop (constant bit rate) optical networks, are discussed in general and demonstrated numerically in a WDM ring. Presented results show that the network cost reduction achieved by the M&M design is a function of the cost ratio between the optical bandwidth (wavelengths) and the optical terminals 相似文献
34.
Time-dependent correlation functions of the conformations of a single gaussian polymer chain immersed in a solvent are calculated renormalization-group theoretically. As a byproduct is is confirmed that to order ? (=4-d, d being the spatial dimensionality) the translational diffusion constant obtained fully dynamically (i.e. by the Green-Kubo formalism) is identical to that obtained by the Kirkwood theory (or the Kirkwood-Riseman formalism) even with the self-avoiding interaction. 相似文献
35.
David Reynolds Anthony J. Mulholland Jagannathan Gomatam 《Journal of mathematical chemistry》1997,22(1):25-37
We present a new class of techniques for the solution of the chemical and phase equilibria problem for reacting species in a closed system. The minimisation of the Gibbs free energy for all the species in the system is conducted using the technique of simulated annealing (SA). The SA objective function incorporates non‐ideal equations of state. This new approach is demonstrably able to solve multi‐species and multi‐phase LTCE problems in ideal‐gas solutions, ideal solutions and mixtures of ideal and non‐ideal solutions. 相似文献
36.
Sridhar Jagannathan 《国际流体数值方法杂志》1992,14(7):793-815
In the simulation of non-linear free surface flows in a finite domain a major concern is with the radiation condition to be applied at the ‘open’ boundary. No general theoretical radiation conditions are known to exist. In this paper a new open boundary condition is formulated based on energy flux equalization between the non-linear inner domain and a linear outer domain. The non-linear flow in the inner domain is solved numerically using a semi-Lagrangian procedure. The energy flux arriving at the open boundary is removed using a new open boundary condition which acts as a linear wave absorber. For the cases studied the performance of this boundary condition is found to be quite good. 相似文献
37.
Jagannathan S. Zawodniok M. Shang Q. 《Wireless Communications, IEEE Transactions on》2006,5(3):540-549
In this paper, a novel distributed power control (DPC) scheme for cellular network in the presence of radio channel uncertainties such as path loss, shadowing, and Rayleigh fading is presented. Since these uncertainties can attenuate the received signal strength and can cause variations in the received signal-to-interference ratio (SIR), a new DPC scheme, which can estimate the slowly varying channel uncertainty, is proposed so that a target SIR at the receiver can be maintained. Further, the standard assumption of a constant interference during a link's power update used in other works in the literature is relaxed. A CDMA-based cellular network environment has been developed to compare the proposed scheme with earlier approaches. The results show that our DPC scheme can converge faster than others by adapting to the channel variations. In the presence of channel uncertainties, our DPC scheme renders lower outage probability while consuming significantly low power per active mobile user compared with other schemes that are available in the literature. 相似文献
38.
The diffraction image patterns of small particles are referred to as their point spread function (PSF); these patterns vary
distinctively with the refractive index (RI) of a transparent test medium when the particles are imaged through the medium.
The RI correlates directly with the mixture concentration, so proper inversion of measured PSFs can provide full-field information
on the mixture concentration field. In this study, fluorescent nanoparticles of 500 nm diameter are fixed on a glass surface
by means of evaporative self-assembly, and the time-varying test mixture is placed in front of the glass surface. The time-varying
and full-field PSF distributions are imaged and digitally analyzed to determine the local RI values as well as the local mixture
concentrations. Both immiscible water/oil mixture and miscible water/glycerol mixture are imaged. The present method shows
an RI measurement to have an uncertainty of ±5 × 10−3 RIU and the mixture concentration measurements to have uncertainty of approximately 4%. 相似文献
39.
Sang-Young Lee Jong Hyeok Park Pilkyu Park Jong Hun Kim Soonho Ahn Kyeong-Jik Lee Hyung-Dong Lee Jae-Sung Park Deok-Hyeong Kim Yeon Uk Jeong 《Journal of Solid State Electrochemistry》2010,14(6):951-956
Multi-walled carbon nanotube (MWCNT) with bundle-type morphology was introduced as a new functional additive working as a
particle connector or an expansion absorber in the anodes of lithium-ion batteries. By controlling the dispersion process,
the MWCNT bundles were successfully divided and dispersed between the host particles. The composite anode consisting of rounded
shape natural graphite and 2 wt.% of MWCNT exhibited the capacity of 300 mAh g−1 at 3 C rate and excellent cyclability. The well-dispersed MWCNT bundles made it possible to relieve the large strains developed
at high discharge C rates and to keep the electrical contact between the host particles during repeated intercalation/deintercalation.
This study has also emphasized that when high C-rate applications of lithium-ion batteries are targeted, it is important to
get optimum content of MWCNT as well as uniform dispersion of their bundles in the composite anodes. 相似文献
40.
Uma Sharma Rajiv R. Singh Vineet Ahuja Govind K. Makharia Naranamangalam R. Jagannathan 《Magnetic resonance imaging》2010