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151.
It has been established that in the presence of elastic as well as surface tension forces, a jump can occur in the bubble
velocity-bubble volume plot. It was proposed that this phenomenon was the result of an elastic instability at the bubble interface,
which drastically changes the local boundary conditions. The origin of this change was mainly attributed to the magnitude
of the elastic forces, which can extract surface active impurities at the gas-liquid interface. The purpose of this paper
is to present photographic evidence of this hypothesis and to confirm past results.
Received: 4 December 1998 Accepted: 17 February 1999 相似文献
152.
Clafton SN Beattie DA Mierczynska-Vasilev A Acres RG Morgan AC Kee TW 《Langmuir : the ACS journal of surfaces and colloids》2010,26(23):17785-17789
We present strong evidence for the oxidation of conjugated polymers in the formation of conjugated polymer dots (CPdots) using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Although recent studies show that folding of the polymer chain into a compact 3D structure is involved in the formation of these nanoparticles, the process by which these intrinsically hydrophobic nanoscale particles circumvent aggregation in water is still not well understood. Zeta potential results show that these dots have a negatively charged surface at neutral pH, with a zeta potential and surface charge density of approximately -40 mV and (1.39 - 1.70) × 10(-2) C/m(2), respectively. In addition, quantitative elemental analysis of CPdots indicates that oxygen composes 7-13% of these nanoparticles. The overall results support the presence of chemical defects in forming a hydrophilic surface of CPdots. As a consequence, the charged surface contributes to inhibiting the aggregation of CPdots in water, leading to colloidal stability. 相似文献
153.
Sang-Ok Kim Heung-Taek Shim Joong Kee Lee 《Journal of Solid State Electrochemistry》2010,14(7):1247-1253
Four different kinds of diamond-like carbon (DLC) coating morphologies on the surface of silicon films were prepared directly
on a copper foil by using radio frequency plasma-enhanced chemical vapor deposition at 200 °C. A thin double layer film consisting
of DLC (60 nm) and silicon film (250 nm) was fabricated for use as the anode material of lithium secondary batteries, and
its electrochemical performance was also examined with special attention being paid to the surface coverage of the DLC film.
The full coverage of silicon by the DLC film resulted in poor capacity due to the ensuing low reactivity with the lithium
ions. On the other hand, the partial coating of the DLC film on the silicon film not only reduced the capacity fading, but
also increased the discharge capacity during the charge/discharge cycles. These results indicated that the good dispersion
of the DLC coating, obtained by using a smaller coating sector on the silicon film, improved the integrity of the electrode
structure, thus giving higher capacities and reduced capacity fading. 相似文献
154.
A high-resolution high-performance liquid chromatography/electrospray ionization quadrupole time-of-flight tandem mass spectrometry method is described for the analysis of porphyrins in blood, urine and faeces. The gradient elution reversed-phase HPLC system using acetonitrile-methanol-1 m ammonium acetate/acetic acid buffer (pH 5.16) as gradient solvent mixtures was able to separate all porphyrin metabolites, including the type I and type III isomers of uroporphyrin, hepta-, hexa- and penta-carboxylic acid porphyrins and coproporphyrin. The porphyrins were positively identified by the protonated molecules [M+H](+) and further characterized by tandem mass spectrometric analysis with each porphyrin giving a characteristic collisioninduced dissociation product ion spectrum. The mass chromatograms obtained by HPLC/ESI MS are useful for the differential diagnosis of the porphyrias, since each type of porphyria has a typical porphyrin excretion pattern. 相似文献
155.
Armstrong AR Holzapfel M Novák P Johnson CS Kang SH Thackeray MM Bruce PG 《Journal of the American Chemical Society》2006,128(26):8694-8698
The cathode in rechargeable lithium-ion batteries operates by conventional intercalation; Li+ is extracted from LiCoO2 on charging accompanied by oxidation of Co3+ to Co4+; the process is reversed on discharge. In contrast, Li+ may be extracted from Mn4+-based solids, e.g., Li2MnO3, without oxidation of Mn4+. A mechanism involving simultaneous Li and O removal is often proposed. Here, we demonstrate directly, by in situ differential electrochemical mass spectrometry (DEMS), that O2 is evolved from such Mn4+ -containing compounds, Li[Ni(0.2)Li(0.2)Mn(0.6)]O2, on charging and using powder neutron diffraction show that O loss from the surface is accompanied by diffusion of transition metal ions from surface to bulk where they occupy vacancies created by Li removal. The composition of the compound moves toward MO(2). Understanding such unconventional Li extraction is important because Li-Mn-Ni-O compounds, irrespective of whether they contain Co, can, after O loss, store 200 mAhg(-1) of charge compared with 140 mAhg(-1) for LiCoO(2). 相似文献
156.
157.
This contribution suggests some relations between normal-stress differences and shear stress, both in the steady state and in the transient regimes. It shows that the general form of the BKZ-type equation can be used for the discussion of the relations between several material functions. In addition, a geometric interpretation is offered and some examples are discussed. 相似文献
158.
Jun‐Woo Kim Jungwook Kim Keun‐Deuk Lee Kee‐Kahb Koo 《Crystal Research and Technology》2013,48(12):1097-1105
Nucleation kinetics in the cooling crystallization of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) from γ‐butyrolactone was studied by converting total counts/s measured by in situ focused beam reflectance measurement (FBRM) into number of crystals. The classical nucleation rate model, which is derived exclusively from the thermodynamic state for the nucleation and molecular collision frequency, was found to be inadequate to describe the experimentally measured nucleation rates. However, the nucleation rates predicted by the modified classical nucleation rate model, inclusive of an additional temperature term, were found to be in good agreement with those measured in the present work. Furthermore, the metastable zone widths are also found to be more accurately predicted by the modified classical nucleation rate model than the classical approach, which assumes that the mass‐based nucleation rate is an exponential function of supersaturation and is equal to the supersaturation rate. 相似文献
159.
We continue the study of the right finite intersection property under a weaker condition on annihilators, introducing the concept of generalized right finite intersection property (simply, generalized right FIP). We observe the structure of rings with the generalized right FIP and examine the generalized right FIP for various kinds of basic extensions of rings with the property. We show that the generalized right FIP does not go up to polynomial rings, and that the 2-by-2 full matrix ring over a domain has the generalized right FIP. In the process, we also obtain an equivalent condition for which a nonzero polynomial, over the ring of integers modulo n ≥ 2, is a non-zero-divisor. 相似文献
160.
Kyoo Soung Shim Hyun Kyoung Yang Jong Won Chung Yeqing Chen Byung Kee Moon Byung Chun Choi Jung Hyun Jeong Jung Hwan Kim Kwang Ho Kim 《Applied Physics A: Materials Science & Processing》2011,104(1):383-386
Y1−x
La
x
VO4:Eu3+ phosphors were synthesized using a solid-state reaction. The microstructure and surface morphology of the Y1−x
La
x
VO4:Eu3+ phosphors were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. PL measurements
of these phosphors revealed the characteristic Eu3+ emissions due to 5D0→7F1 and 5D0→7F2 transitions. The Y1−x
La
x
VO4:Eu3+ phosphors showed strong red emission at 619 nm, which radiated from the hypersensitive transition 5D0–7F2 of Eu3+ ions. In particular, the incorporation of La into the YVO4 lattice could induce a remarkable increase in PL. The highest emission intensity was observed in Y0.2La0.8VO4:Eu3+, whose brightness was increased by more than 100 fold compared to that of the LaVO4:Eu3+ phosphors. The Y1−x
La
x
VO4:Eu3+ phosphors with highly enhanced luminescence are expected to have applications in display devices. 相似文献