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341.
Colleen Kelley Katy K. Gaither Alexis Baca-Spry Brandon J. Cruickshank 《The Chemical Educator》2000,5(3):140-143
An undergraduate laboratory exercise appropriate for introductory chemistry courses at the high school or college level is presented. The objective of the laboratory is to introduce the idea that plants can be used to remove contaminants from the environment–a process called phytoremediation. This laboratory connects the disciplines of chemistry and biology while enabling students to learn the skills of measurement, titration, calculation of molarity of an unknown solution, graphing, and interpretation of data. 相似文献
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GRAPPA-based susceptibility-weighted imaging of normal volunteers and patients with brain tumor at 7 T 总被引:1,自引:0,他引:1
Lupo JM Banerjee S Hammond KE Kelley DA Xu D Chang SM Vigneron DB Majumdar S Nelson SJ 《Magnetic resonance imaging》2009,27(4):480-488
Susceptibility-weighted imaging (SWI) is a valuable technique for high-resolution imaging of brain vasculature that greatly benefits from the emergence of higher field strength MR scanners. Autocalibrating partially parallel imaging techniques can be employed to reduce lengthy acquisition times as long as the decrease in signal-to-noise ratio does not significantly affect the contrast between vessels and brain parenchyma. This study assessed the feasibility of a Generalized Autocalibrating Partially Parallel Acquisition (GRAPPA)-based SWI technique at 7 T in both healthy volunteers and brain tumor patients. GRAPPA-based SWI allowed a twofold or more reduction in scan time without compromising vessel contrast and small vessel detection. Postprocessing parameters for the SWI needed to be modified for patients where the tumor causes high-frequency phase wrap artifacts but did not adversely affect vessel contrast. GRAPPA-based SWI at 7 T revealed regions of microvascularity, hemorrhage and calcification within heterogeneous brain tumors that may aid in characterizing active or necrotic tumor and monitoring treatment effects. 相似文献
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346.
Vectorization,threading, and cache‐blocking considerations for hydrocodes on emerging architectures
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J. Fung R. T. Aulwes M. T. Bement J. M. Campbell C. R. Ferenbaugh B. A. Jean T. M. Kelley M. A. Kenamond B. R. Lally E. G. Lovegrove E. M. Nelson D. M. Powell 《国际流体数值方法杂志》2015,79(11):596-613
The computational efficiency of existing hydrocodes is expected to suffer as computer architectures advance beyond the traditional parallel central processing unit (CPU) model 1 . Concerning new computer architectures, sources of relative performance degradation might include reduced memory bandwidth per core, increased resource contention due to concurrency, increased single instruction, multiple data (SIMD) length, and increasingly complex memory hierarchies. Concerning existing codes, any performance degradation will be influenced by a lack of attention to performance in their design and implementation. This work reports on considerations for improving computational performance in preparation for current and expected changes to computer architecture. The algorithms studied will include increasingly complex prototypes for radiation hydrodynamics codes, such as gradient routines and diffusion matrix assembly (e.g., in 1 - 6 ). The meshes considered for the algorithms are structured or unstructured meshes. The considerations applied for performance improvements are meant to be general in terms of architecture (not specifically graphical processing unit (GPUs) or multi‐core machines, for example) and include techniques for vectorization, threading, tiling, and cache blocking. Out of a survey of optimization techniques on applications such as diffusion and hydrodynamics, we make general recommendations with a view toward making these techniques conceptually accessible to the applications code developer. Published 2015. This article is a U.S. Government work and is in the public domain in the USA. 相似文献
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348.
A Glycan Array-Based Assay for the Identification and Characterization of Plant Glycosyltransferases
Dr. Colin Ruprecht Dr. Max P. Bartetzko Dr. Deborah Senf Dr. Anna Lakhina Dr. Peter J. Smith Dr. Maria J. Soto Hyunil Oh Dr. Jeong-Yeh Yang Dr. Digantkumar Chapla Dr. Daniel Varon Silva Prof. Dr. Mads H. Clausen Prof. Dr. Michael G. Hahn Prof. Dr. Kelley W. Moremen Prof. Dr. Breeanna R. Urbanowicz Prof. Dr. Fabian Pfrengle 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(30):12593-12598
Growing plants with modified cell wall compositions is a promising strategy to improve resistance to pathogens, increase biomass digestibility, and tune other important properties. In order to alter biomass architecture, a detailed knowledge of cell wall structure and biosynthesis is a prerequisite. We report here a glycan array-based assay for the high-throughput identification and characterization of plant cell wall biosynthetic glycosyltransferases (GTs). We demonstrate that different heterologously expressed galactosyl-, fucosyl-, and xylosyltransferases can transfer azido-functionalized sugar nucleotide donors to selected synthetic plant cell wall oligosaccharides on the array and that the transferred monosaccharides can be visualized “on chip” by a 1,3-dipolar cycloaddition reaction with an alkynyl-modified dye. The opportunity to simultaneously screen thousands of combinations of putative GTs, nucleotide sugar donors, and oligosaccharide acceptors will dramatically accelerate plant cell wall biosynthesis research. 相似文献
349.
Spectroscopic and Computational Characterization of Diethylenetriaminepentaacetic Acid/Transplutonium Chelates: Evidencing Heterogeneity in the Heavy Actinide(III) Series
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Dr. Gauthier J.‐P. Deblonde Dr. Morgan P. Kelley Dr. Jing Su Dr. Enrique R. Batista Dr. Ping Yang Dr. Corwin H. Booth Prof. Rebecca J. Abergel 《Angewandte Chemie (International ed. in English)》2018,57(17):4521-4526
The chemistry of trivalent transplutonium ions (Am3+, Cm3+, Bk3+, Cf3+, Es3+…) is usually perceived as monotonic and paralleling that of the trivalent lanthanide series. Herein, we present the first extended X‐ray absorption fine structure (EXAFS) study performed on a series of aqueous heavy actinide chelates, extending past Cm. The results obtained on diethylenetriaminepentaacetic acid (DTPA) complexes of trivalent Am, Cm, Bk, and Cf show a break to much shorter metal–oxygen nearest‐neighbor bond lengths in the case of Cf3+. Corroborating those results, density functional theory calculations, extended to Es3+, suggest that the shorter Cf?O and Es?O bonds could arise from the departure of the coordinated water molecule and contraction of the ligand around the metal relative to the other [MIIIDTPA(H2O)]2? (M=Am, Cm, Bk) complexes. Taken together, these experimental and theoretical results demonstrate inhomogeneity within the trivalent transplutonium series that has been insinuated and debated in recent years, and that may also be leveraged for future nuclear waste reprocessing technologies. 相似文献
350.
Benzylic Fluorination of Aza‐Heterocycles Induced by Single‐Electron Transfer to Selectfluor
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Kelley E. Danahy Julian C. Cooper Prof. Dr. Jeffrey F. Van Humbeck 《Angewandte Chemie (International ed. in English)》2018,57(18):5134-5138
A selective and mild method for the benzylic fluorination of aromatic azaheterocycles with Selectfluor is described. These reactions take place by a previously unreported mechanism, in which electron transfer from the heterocyclic substrate to the electrophilic fluorinating agent Selectfluor eventually yields a benzylic radical, thus leading to the desired C?F bond formation. This mechanism enables high intra‐ and intermolecular selectivity for aza‐heterocycles over other benzylic components with similar C?H bond‐dissociation energies. 相似文献