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排序方式: 共有388条查询结果,搜索用时 15 毫秒
91.
The chemical vapor deposition (CVD) of crystalline thin films of neodymium hexaboride (NdB6) was achieved using either nido ‐pentaborane(9) or nido ‐decaborane(14) with neodymium(III) chloride on different substrates. The highly crystalline NdB6 films were formed at relatively moderate temperatures (835 °C, ca. 1 µm/h) and were characterized by scanning electron microscopy, X‐ray emission spectroscopy, X‐ray diffraction and glow discharge mass spectrometry. The NdB6 polycrystalline films were found to be pure and uniform in composition in the bulk material. Depositions using CoCl2, NdCl3 and B5H9 as the CVD precursors resulted in the formation of a mixture of NdB6 and CoB phases, rather than the ternary phase. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
92.
Evaluations of the energy for thermonuclear ignition of a compressed deuterium-tritium mixture contaminated by a high-Z material are presented. Mixing at the atomic level is considered and the results are given as a function of the contaminant fraction. The reference situation is that of cone-focused fast ignition (CFFI). The numerical 2D simulations for this study were performed by a Lagrangian 2D hydrocode that includes real matter EoS, real matter opacity coefficients, and packages for finite-range energy deposition by reaction products and the relative in-flight reactions. A simple estimate is presented for the effects of high-Z material blobs on the ignition energy (macroscopic mixing). Possible sources for fuel contamination in CFFI are discussed. 相似文献
93.
94.
Feng DQ Caruso AN Schulz DL Losovyj YB Dowben PA 《The journal of physical chemistry. B》2005,109(34):16382-16389
We compare two mechanisms that dominate the temperature-dependent changes in electronic structure for poly(3-hexylthiophene-2,5 diyl) (P3HT). Structural changes in the relative orientation and configuration of the aromatic ring backbone are observed to occur over a wide range in temperature and affect the local final state screening in photoemission. There are also changes in conductivity and carrier concentration at lower temperatures leading to altered long-range intramolecular screening of photoholes and final state effects that affect excitation spectroscopies including photoemission. For polyethylenedioxythiophene (PEDOT), temperature-dependent changes in the structure and configuration of the polymer backbone are not as significant, although temperature-dependent final state effects are observed. 相似文献
95.
Mercedes Camalli Francesco Caruso Stanislav Chaloupka Ernest M. Leber Heinrich Rimml Luigi M. Venanzi 《Helvetica chimica acta》1990,73(8):2263-2274
The preparation of complexes [MX2( 1 )] (M = Ni, Pd, and Pi; X - Cl, Br, and I; 1 = 1,2-bis[(diphenylphosphino)methyl]benzene). [Pt(OSO2CH3)Et( 1 )], [Pt(alkene)( 1 )] (alkene - C2H2, and CH2 = CHCN), and [( 1 )Pt-(μ-H)2PtH( 1 )][BPh4] is reported. Their 1H- and 31P-NMR spectra were recorded and used lor structural assignments. The X-ray crystal structure of [Pt(C2H4)( 1 )] was determined. It is shown that the P? Pt? P bond angle in this complex differs significantly from those found in related compounds with monodentate phosphines, and that this difference is likely to be due to intramolecular contacts. 相似文献
96.
Various selenium- and sulfur-containing volatiles have been detected and characterized as products of chalcogen exchange reactions. The formation of all possible selenium- and sulfur-containing trichalcogenide isomers (-SeSS-, -SSeS-, -SeSeS-, -SeSSe- and -SeSeSe-) was observed at room temperature in the solutions containing diselenide and trisulfide. Because of the low activation barrier of the selenium exchange reaction, these species are expected also to form in biological systems in the presence of diselenides and higher sulfides. Methyl and ethyl derivatives of these species were characterized using gas chromatography coupled to time-of-flight mass spectrometry with electron impact, chemical, and field ionization. Rearrangements of triselenides lead also to the formation of isomeric branched-structure triselenides, selanadiselenides. Because of the very similar structural properties, the behavior of these novel species was studied under various ionization modes (EI+, CI+, EI-, and CI-). 相似文献
97.
Grant TD Montes-Bayón M LeDuc D Fricke MW Terry N Caruso JA 《Journal of chromatography. A》2004,1026(1-2):159-166
The present work shows the identification and characterization of Se-methyl selenomethionine (SeMMet) as an important Se species in Brassica juncea roots when grown in the presence of Se-methionine (SeMet) as the Se source. SeMMet was isolated by liquid chromatography employing two different liquid chromatographic mechanisms: reversed-phase ion-pairing using heptafluorobutyric acid as counter ion and cation exchange using a pyridinium formate gradient (pH 3). Inductively coupled plasma mass spectrometry was used for the detection of Se. SeMMet was characterized by electrospray quadrupole time-of-flight MS in both a synthesized standard and in the roots extract using collision-induced dissociation of the selected ion. Preliminary evidence suggests that Brassica juncea may also produce dimethylselenonium propionate, although to a much lesser extent. 相似文献
98.
U. Caruso B. Panunzi A. Roviello A. Sirigu D. Spasiano 《Journal of polymer science. Part A, Polymer chemistry》2001,39(13):2342-2349
Rigid‐chain metallomesogenic polymers containing Cu(II) or VO(II) were prepared and characterized. All the polymers were soluble and melted without decomposition. They showed a thermotropic liquid–crystal (LC) behavior, and the mesophases were invariably preserved for a long time at room temperature in a metastable condition, with respect to the semicrystalline state. The nature of the mesophases of the Cu(II)‐containing polymers was similar to that observed in analogous organic rigid‐chain polymers having long lateral alkyl chains packed as extended ribbons. The VO(II)‐containing polymers showed an LC polymorphism involving a smectic A and a nematic phase. For all the polymers in a smectic or smecticlike state at room temperature, X‐ray diffraction data suggested short mean distances among the metal ions arranged in layers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2342–2349, 2001 相似文献
99.
R V Mulkern S Vajapeyam R L Robertson P A Caruso M J Rivkin S E Maier 《Magnetic resonance imaging》2001,19(5):659-668
The decay of brain water signal with b-factor in adult and newborn brains has been measured over an extended b-factor range. Measurements of the apparent diffusion coefficient (ADC) decay curves were made at 16 b-factors from 100 to 5000 s/mm(2) along three orthogonal directions using a line scan diffusion imaging (LSDI) sequence to acquire data from 0.09 ml voxels in a mid-brain axial slice. Regions-of-interest (ROIs) in cortical gray (CG) and white matter in the internal capsule (IC) were selected for ADC decay curve analyses using a biexponential fitting model over this extended b-factor range. Measures of the fast and slow ADC component amplitudes and the traces of the fast and slow diffusion coefficients were obtained from CG and IC ROIs in both adults and newborns. The ADC decay curves from the newborn brain regions were found to have a significantly higher fraction of the fast diffusion ADC component than corresponding regions in the adult brain. The results demonstrate that post-natal brain development has a profound affect on the biexponential parameters which characterize the decay of water signal over an extended b-factor range in both gray and white matter. 相似文献
100.
Yiyuan Han Zhixing Lin Dr. Jiajing Zhou Dr. Gyeongwon Yun Rui Guo Dr. Joseph J. Richardson Prof. Frank Caruso 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(36):15748-15755
Functional materials composed of proteins have attracted much interest owing to the inherent and diverse functionality of proteins. However, establishing general techniques for assembling proteins into nanomaterials is challenging owing to the complex physicochemical nature and potential denaturation of proteins. Here, a simple, versatile strategy is introduced to fabricate functional protein assemblies through the interfacial assembly of proteins and polyphenols (e.g., tannic acid) on various substrates (organic, inorganic, and biological). The dominant interactions (hydrogen-bonding, hydrophobic, and ionic) between the proteins and tannic acid were elucidated; most proteins undergo multiple noncovalent stabilizing interactions with polyphenols, which can be used to engineer responsiveness into the assemblies. The proteins retain their structure and function within the assemblies, thereby enabling their use in various applications (e.g., catalysis, fluorescence imaging, and cell targeting). 相似文献