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排序方式: 共有196条查询结果,搜索用时 31 毫秒
51.
Silva LO Marti M Davies JR Fonseca RA Ren C Tsung FS Mori WB 《Physical review letters》2004,92(1):015002
The formation of strong, high Mach number (2-3), electrostatic shocks by laser pulses incident on overdense plasma slabs is observed in one- and two-dimensional particle-in-cell simulations, for a wide range of intensities, pulse durations, target thicknesses, and densities. The shocks propagate undisturbed across the plasma, accelerating the ions (protons). For a dimensionless field strength parameter a(0)=16 (Ilambda(2) approximately 3 x 10(20) W cm(-2) microm(2), where I is the intensity and lambda the wavelength), and target thicknesses of a few microns, the shock is responsible for the highest energy protons. A plateau in the ion spectrum provides a direct signature for shock acceleration. 相似文献
52.
The first three-dimensional, particle-in-cell (PIC) simulations of laser-wakefield acceleration of self-injected electrons in a 0.84 cm long plasma channel are reported. The frequency evolution of the initially 50 fs (FWHM) long laser pulse by photon interaction with the wake followed by plasma dispersion enhances the wake which eventually leads to self-injection of electrons from the channel wall. This first bunch of electrons remains spatially highly localized. Its phase space rotation due to slippage with respect to the wake leads to a monoenergetic bunch of electrons with a central energy of 0.26 GeV after 0.55 cm propagation. At later times, spatial bunching of the laser enhances the acceleration of a second bunch of electrons to energies up to 0.84 GeV before the laser pulse intensity is significantly reduced. 相似文献
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54.
Ho Chang Tsing-Tshin Tsung Hong-Ming Lin * Chung-Kwei Lin Department of Mechanical Engineering Taipei University of Technology Taipei China Department of Materials Engineering Tatung University Taipei China Department of Materials Science Feng-Chia University Taichung China 《中国颗粒学报》2004,2(4):171-173
1. Inroduction Since TiO2 nanoparticles possess such characteristics as strong reduction and oxidation capabilities, high chemical stability, harmlessness to the environment, and low cost of production, it has been used as a new type of photocatalyst as well as anti-bacterium and anti-fungus agent, air and water purifier, and photosynthesis material (Jang et al., 2001). According to the principle based on gas condensation, the present study describes a combined vacuum Arc-Submerged Nanoparti… 相似文献
55.
A manganese‐catalyzed cross‐coupling reaction of thiols with aryl iodides, furnishing aryl thioethers in good to excellent yields has been reported; the system shows good functional group tolerance and enables the sterically demanding aryl iodides to couple with thiols. 相似文献
56.
M. Tzoufras A.R. Bell P.A. Norreys F.S. Tsung 《Journal of computational physics》2011,230(17):6475-6494
OSHUN is a parallel relativistic 2D3P Vlasov–Fokker–Planck code, developed primarily to study electron transport and instabilities pertaining to laser-produced—including laser-fusion—plasmas. It incorporates a spherical harmonic expansion of the electron distribution function, where the number of terms is an input parameter that determines the angular resolution in momentum-space. The algorithm employs the full 3D electromagnetic fields and a rigorous linearized Fokker–Planck collision operator. The numerical scheme conserves energy and number density. This enables simulations for plasmas with temperatures from MeV down to a few eV and densities from less than critical to more than solid. Kinetic phenomena as well as electron transport physics can be recovered accurately and efficiently. 相似文献
57.
Chun‐Kai Wang Xiaozhou Che Yuan‐Chih Lo Ya‐Ze Li Yung‐Hao Wang Stephen R. Forrest Shun‐Wei Liu Ken‐Tsung Wong 《化学:亚洲杂志》2020,15(16):2520-2531
Four new donor‐acceptor‐acceptor’ (D‐A‐A’)‐configured donors, CPNT , DCPNT , CPNBT , and DCPNBT equipped with naphtho[1,2‐c:5,6‐c′]bis([1,2,5]‐thiadiazole) (NT) or naphtho[2,3‐c][1,2,5]thiadiazole (NBT) as the central acceptor (A) unit bridging triarylamine donor (D) and cyano or dicyanovinylene acceptor (A’), were synthesized and characterized. All molecules exhibit bathochromic absorption shifts as compared to those of the benzothiadiazole (BT)‐based analogues owing to improved electron‐withdrawing and quinoidal character of NT and NBT cores that lead to stronger intramolecular charge transfer. Favorable energy level alignments with C70, together with the good thermal stability and the antiparallel dimeric packing render CPNT and DCPNT suitable donors for vacuum‐processed organic photovoltaics (OPV)s. OPVs based on DCPNT : C70 active layers displayed the best power conversion efficiency (PCE)=8.3%, along with an open circuit voltage of 0.92 V, a short circuit current of 14.5 mA cm?2 and a fill factor of 62% under 1 sun intensity, simulated AM1.5G illumination. Importantly, continuous light‐soaking with AM 1.5G illumination has verified the durability of the devices based on CPNT :C70 and DCPNT : C70 as the active blends. The devices were examined for their feasibility of indoor light harvesting under 500 lux illumination by a TLD‐840 fluorescent lamp, giving PCE=12.8% and 12.6%, respectively. These results indicate that the NT‐based D‐A‐A’‐type donors CPNT and DCPNT are potential candidates for high‐stability vacuum‐processed OPVs suitable for indoor energy harvesting. 相似文献
58.
Rotaxanes Synthesized Through Sodium‐Ion‐Templated Clipping of Macrocycles Around Nonconjugated Amide and Urea Functionalities
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Tsung‐Hsien Ho Prof. Chien‐Chen Lai Yi‐Hung Liu Prof. Shie‐Ming Peng Prof. Sheng‐Hsien Chiu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(16):4563-4567
A single urea or amide functionality in a dumbbell‐shaped guest can be “clipped” by a macrocycle generated from a diamine and a dialdehyde through the templating effect of a Na+ ion (see scheme). The resulting imine‐containing rotaxanes can then be reduced to allow isolation of stable amine‐based rotaxanes. 相似文献
59.
60.
The Solitary Isomer of C60H18 Is Proven to Have a C3v Crown Shape: Crystal Structure Determination and Synthesis of Its Triruthenium Cluster Complex
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Dr. Chi‐Shian Chen Tsung‐Han Chuang Yi‐Hung Liu Dr. Wen‐Yann Yeh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(48):17229-17233
Analytically pure C60H18 is obtained by a Ru3 cluster complexation and decomplexation method. The crystal structure of C60H18 consists of one flattened hemisphere, to which all 18 hydrogen atoms are symmetrically bonded, and one curved hemisphere akin to C60. A benzenoid ring in the flattened hemisphere is isolated from the residual π systems by a belt composed of sp3‐hybridized CH units. The average out‐of‐plane distances for carbon atoms attached to the benzenoid ring (0.14 Å) is substantially larger than that found in C60F18 (0.06 Å). Several long C(sp3)?C(sp3) single bond lengths [1.61(3)–1.65(3) Å] are observed for C60H18. The reaction of [Ru3(CO)12] and C60H18 produces [Ru3(CO)9(μ3‐η2,η2,η2‐C60H18)] ( 1 ), where the Ru3 triangle is regiospecifically linked to the hexagon opposite to the benzenoid ring. Compound 1 is the first transition metal complex of a polyhydrofullerene (fullerane). C60H18 and 1 have been characterized by 1H and 13C NMR, UV/Vis, and mass spectroscopies. The HOMO–LUMO gap of C60H18 is evaluated to be 1.51 V by cyclic voltammetry. 相似文献