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排序方式: 共有379条查询结果,搜索用时 15 毫秒
51.
Melamine cyanurate-microencapsulated red phosphorus flame retardant unreinforced and glass fiber reinforced polyamide 66 总被引:1,自引:0,他引:1
A novel microencapsulated red phosphorus (RP) was prepared through the molecular self-assembly of melamine cyanurate (MCA). Compared with the conventional encapsulated RP, MCA-encapsulated RP (MERP) shows simpler and more environment-friendly preparation process higher thermal stability and lower moisture absorption. With MERP filled in unreinforced polyamide 66 (PA66) and glass fiber (GF) reinforced PA66, flame retardant materials with satisfactory flame retardancy and mechanical performance can be obtained. The influence of the MCA/RP ratio on the flame retardancy as well as the condensed phase of MERP flame retardant PA66 was investigated to reveal the nitrogen-phosphorus (N-P) synergistic flame retarding effects between MCA and RP. 相似文献
52.
Tianyue Qian Huacheng Zhang Xingya Li Jue Hou Chen Zhao Qinfen Gu Huanting Wang 《Angewandte Chemie (International ed. in English)》2020,59(31):13051-13056
1D nanochannels modified with responsive molecules are fabricated to replicate gating functionalities of biological ion channels, but gating effects are usually weak because small molecular gates cannot efficiently block the large channels in the closed states. Now, 3D metal–organic framework (MOF) sub‐nanochannels (SNCs) confined with azobenzene (AZO) molecules achieve efficient light‐gating functionalities. The 3D MOFSNCs consisting of a MOF UiO66 with ca. 9–12 Å cavities connected by ca. 6 Å triangular windows work as angstrom‐scale ion channels, while confined AZO within the MOF cavities function as light‐driven molecular gates to efficiently regulate the ion flux. The AZO‐MOFSNCs show good cyclic gating performance and high on–off ratios up to 17.8, an order of magnitude higher than ratios observed in conventional 1D AZO‐modified nanochannels (1.3–1.5). This work provides a strategy to develop highly efficient switchable ion channels based on 3D porous MOFs and small responsive molecules. 相似文献
53.
LI Xiaoshuang LIU Yuan GUO Chaofeng LIU Haiyang WANG Gang CAI Qiang YAO Youwei 《高等学校化学研究》2016,32(1):127-133
A layered aluminoborophosphate(LABP-DDA) was hydrothermally synthesized using dodecylamine as a structure-directing agent, and was added into polyamide 66(PA66) to obtain nanocomposites, PA66/LABP-DDA, via melt intercalation method. The characterization results of transmission electron microscopy(TEM) and small angle X-ray scattering (SAXS) indicate that LABP-DDA has been successfully exfoliated into nano-layers of PA66 matrix. The unstable γ phase of PA66 was found in the composites with the help of X-ray diffraction(XRD) and differential scanning calorimetry(DSC). The heterogeneous nucleation effect of LABP-DDA resulted in an increasement of about 10℃ in melting temperature and an increasement of about 7% in crystallinity when compared with those of neat PA66. The introduction of LABP-DDA did not significantly affect the toughness and strength of PA66. The results of flammability test indicate that LABP-DDA possesses positive synergistic flame retarding effect in the presence of melamine polyphosphate(MPP) and the 77%PA66/(23-x)%MPP/x%LABP-DDA(x=1, 2) samples in thickness of 1.6 mm reached from Fail to V-1 rating based on UL94, compared with 77%PA66/23%MPP. 相似文献
54.
Jacques Helmstetter 《Advances in Applied Clifford Algebras》2008,18(2):153-196
A meson algebra is involved in the Duffin wave equation for mesons in the same way as a Clifford algebra is involved in the
Dirac wave equation for electrons. Therefore meson algebras too should have geometrical properties after the manner of Grassmann.
Actually it is possible to define interior multiplications with similar properties, and deformations too. Every meson algebra
is a deformation of a neutral meson algebra, in the same way as (almost) every Clifford algebra is a deformation of an exterior
algebra. Some applications follow: the PBW-property is proved for all meson algebras, the injectiveness of Jacobson’s diagonal
morphism is proved with the minimal hypothesis, and the existence of Lipschitz monoids is established at least for meson algebras
over fields.
相似文献
55.
56.
《Analytica chimica acta》2004,512(1):103-110
The molecular weight of biopolymers such as peptides or proteins is vital information for understanding their physical/chemical properties. The matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and size-exclusion chromotography-multi-angle laser light scattering (SEC-MALLS) techniques each with its advantages and limitations were used for molecular weight determination of the SPf66 peptide. The precision of each method was studied using a two-factor fully-nested design with all the analyses performed by the same operator on a single instrument. The overall precision corresponded to the time-different intermediate precision (i.e. time and repeatability conditions). In the case of SEC-MALLS, all potential uncertainty components were carefully evaluated in an Ishikawa diagram, then included and mathematically combined with the uncertainty arising from the accuracy assessment to provide the overall uncertainty. In this case, the refractive-index increment with solute concentration value (dn/dc) provided the most significant contribution to the combined uncertainty. A method for its quantitation is proposed. The accuracy of method B (SEC-MALLS) against reference method A (MALDI-TOF-MS) was assessed using the interval testing hypothesis to limit the risk of unacceptable bias. The results indicate that the bias of B is higher than the limit established at 5%, and is therefore not traceable to A under the studied conditions. 相似文献
57.
A simple and commonly used method to approximate the total claim distribution of a (possibly weakly dependent) insurance collective is the normal approximation. In this article, we investigate the error made when the normal approximation is plugged in a fairly general distribution-invariant risk measure. We focus on the rate of convergence of the error relative to the number of clients, we specify the relative error’s asymptotic distribution, and we illustrate our results by means of a numerical example. Regarding the risk measure, we take into account distortion risk measures as well as distribution-invariant coherent risk measures. 相似文献
58.
Shenzhen Cong Yunqi Zhou Chenglian Luo Caixia Wang Prof. Jixiao Wang Prof. Zhi Wang Prof. Xinlei Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(15):e202319894
Membrane-based separation has the merit of low carbon footprint. In this study, the pore size of metal–organic framework (MOF) membranes is rationally designed for discriminating various pairs of hydrocarbon isomers. Specifically, Zr-MOF UiO-66 (UiO stands for University of Oslo) membranes are developed for separating p/o-xylene due to their proper pore size. For n-hexane/2-methylpentane separation, the functional groups and proportion of the ligands in UiO-66 are gradually adjusted to effectively regulate the pore size, and UiO-66-33Br membranes are constructed. In addition, relying on the utilization of ligands with shorter length, MOF-801 membranes with smaller pore size are fabricated for n/i-butane separation. 相似文献
59.
Valentina Georgievna Ponomareva Elena Sergeevna Shutova Konstantin Aleksandrovich Kovalenko Vladimir Petrovich Fedin 《Molecules (Basel, Switzerland)》2022,27(23)
New (1−x)CsH2PO4–xUiO-66 electrolytes with high proton conductivity and thermal stability at 230–250 °C were developed. The phase composition and proton conductivity of nanocomposites (x = 0–0.15) were investigated in detail. As shown, the UiO-66 matrix is thermally and chemically suitable for creating composites based on CsH2PO4. The CsH2PO4 crystal structure remains, but the degree of salt crystallinity changes in nanocomposites. As a result of interface interaction, dispersion, and partial salt amorphization, the proton conductivity of the composite increases by two orders of magnitude in the low-temperature range (up to 200 °C), depending on the UiO-66 fraction, and goes through a maximum. At higher temperatures, up to 250 °C, the conductivity of nanocomposites is close to the superprotonic values of the original salt at low UiO-66 values; then, it decreases linearly within one order of magnitude and drops sharply at x > 0.07. The stability of CsH2PO4-UiO-66 composites with high proton conductivity was shown. This creates prospects for their use as proton membranes in electrochemical devices. 相似文献
60.
Incorporation of phosphorus into silicon from a spin-on dopant layer (SOD) at 400 °C is described.
Annealing experiments were carried out with SOD films deposited on (100) silicon substrates by using the spin-on technique.
Conventional heating on a hotplate in normal atmosphere and a temperature range up to 400 °C was used to study the dopant incorporation. After removing the SOD-films one part of the silicon substrates was annealed
at higher temperatures. Investigations were carried out by SIMS, SAM, XPS, HTEM, stripping Hall and Van der Pauw measurements
before and after the high temperature annealing.
Chemical phosphorus concentration profiles obtained from low temperature annealed samples showed diffusion depths of 60–80 nm
(extrapolated to a substrate doping level of 1016 cm-3) and surface concentrations of 1019–1020 cm-3. Electron concentration profiles exhibiting maximum values around 2⋅1019 cm-3 could be measured on high temperature annealed samples only.
Received: 28 March 1996/Accepted: 19 August 1996 相似文献