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91.
The synthesis of a novel rotenone-like molecule, 9-methoxy-8-methyl-6,6a,12,12a-tetrahydro[1]benzopyrano-[3,4-b][1]benzopyran-12-one ( 2 ) is described. Efficient syntheses of 3,4-dihydro-2H-[1]benzopyran-3-one ( 9 ) from ethyl 3-hydroxy-2H-[1]benzopyran-4-carboxylate ( 6 ), an intermediate in the synthesis of 2 , were developed. Thermolysis of 6 and 9 in decalin yielded 6,8-dihydro-14H-bis[1]benzopyrano[3,4-b:4′,3′-e]pyran-14-one ( 8 ), which has previously been described. Also produced in the thermolysis was the isomeric 1H-bis[1]-benzopyrano[3,4-b:3′,4′-á]pyran-7-(9H)one ( 10 ), the first member of a novel, pentacyclic ring system. 相似文献
92.
Adams DC Inampudi S Ribaudo T Slocum D Vangala S Kuhta NA Goodhue WD Podolskiy VA Wasserman D 《Physical review letters》2011,107(13):133901
We present a comprehensive study of enhanced light funneling through a subwavelength aperture with realistic (lossy) epsilon-near-zero (ENZ) materials. We realize experimentally an inclusion-free ENZ material layer operating at optical frequencies and characterize its performance. An analytical expression describing light funneling through several structures involving ENZ coupling layers is developed, validated with numerical solutions of Maxwell equations, and utilized to relate the performance of the ENZ coupling systems to their main limiting factor, material losses. 相似文献
93.
Transport through symmetric parallel coupled quantum dot system has been studied, using non-equilibrium Green function formalism.
The inter-dot tunnelling with on-dot and inter-dot Coulomb repulsion is included. The transmission coefficient and Landaur-Buttiker
like current formula are shown in terms of internal states of quantum dots. The effect of inter-dot tunnelling on transport
properties has been explored. Results, in intermediate inter-dot coupling regime show signatures of merger of two dots to
form a single composite dot and in strong coupling regime the behaviour of the system resembles the two decoupled dots.
相似文献
94.
95.
H. C. Verma S. Misra M. Shyam Prasad N. Bijlani A. Tripathi Horton Newsom 《Hyperfine Interactions》2008,182(1-3):15-22
The partly filled skutterudites A x Fe4Sb12 (A = La, Pr, Nd, Eu, Yb, and the monovalent homologue Tl) were investigated at 4.2 K by 57Fe Mössbauer spectroscopy in external fields up to 13.5 T. Two Fe sites were identified. The observed relative spectral areas are not for all compounds in agreement with filling factors for the A-atoms determined from X-ray experiments. The change in sign and the small value of the induced hyperfine fields for magnetically ordered compounds are strong hints for itinerant ferromagnetism with small ordered moments. 相似文献
96.
Neil G. Keats Shyam K. Singh Lindsay A. Summers 《Journal of heterocyclic chemistry》1987,24(4):1029-1035
4-Carboxy-5-methyl-2-aryl-2H-1,2,3-triazoles undergo considerable fragmentation on electron impact including loss of OH and H2O from the molecular ions and rupture of the triazole ring. 4-Carboxy-5-phenyl-2-aryl-2H-1,2,3-triazoles, on the other hand, show no loss of H2O from the molecular ions. 相似文献
97.
Mannan Zubaer Ibna Adhikari Shyam Prasad Kim Hyongsuk Chua Leon 《Nonlinear dynamics》2020,99(4):3169-3196
Nonlinear Dynamics - This paper presents an in-depth and rigorous mathematical analysis of a family of nonlinear dynamical circuits whose only nonlinear component is a Chua Corsage Memristor (CCM)... 相似文献
98.
Benjoe Rey B. Visayas Shyam K. Pahari Tugba Ceren Gokoglan James A. Golen Ertan Agar Patrick J. Cappillino Maricris L. Mayes 《Chemical science》2021,12(48):15892
Recent advances in clean, sustainable energy sources such as wind and solar have enabled significant cost improvements, yet their inherent intermittency remains a considerable challenge for year-round reliability demanding the need for grid-scale energy storage. Nonaqueous redox flow batteries (NRFBs) have the potential to address this need, with attractive attributes such as flexibility to accommodate long- and short-duration storage, separately scalable energy and power ratings, and improved safety profile over integrated systems such as lithium-ion batteries. Currently, the low-solubility of NRFB electrolytes fundamentally limits their energy density. However, synthetically exploring the large chemical and parameter space of NRFB active materials is not only costly but also intractable. Here, we report a computational framework, coupled with experimental validation, designed to predict the solubility trends of electrolytes, incorporating both the lattice and solvation free energies. We reveal that lattice free energy, which has previously been neglected, has a significant role in tuning electrolyte solubility, and that solvation free energies alone is insufficient. The desymmetrization of the alkylammonium cation leading to short-chain, asymmetric cations demonstrated a modest increase in solubility, which can be further explored for NRFB electrolyte development and optimization. The resulting synergistic computational–experimental approach provides a cost-effective strategy in the development of high-solubility active materials for high energy density NRFB systems.Active-material solubility is critical in determining NRFB energy density, yet a predictive model accounting for solid-state cohesion energy has remained elusive. Herein we present such, based on an empirically calibrated computational framework. 相似文献
99.
Dey A Kirchner MT Vangala VR Desiraju GR Mondal R Howard JA 《Journal of the American Chemical Society》2005,127(30):10545-10559
The supramolecular synthon approach to crystal structure prediction (CSP) takes into account the complexities inherent in crystallization. The synthon is a kinetically favored unit, and through analysis of commonly occurring synthons in a group of related compounds, kinetic factors are implicitly invoked. The working assumption is that while the experimental structure need not be at the global minimum, it will appear somewhere in a list of computationally generated structures so that it can be suitably identified and ranked upward using synthon information. These ideas are illustrated with a set of aminophenols, or aminols. In the first stage, a training database is created of the 10 isomeric methylaminophenols. The crystal structures of these compounds were determined. The prototypes 2-, 3-, and 4-aminophenols were also included in the training database. Small and large synthons in these 13 crystal structures were then identified. Small synthons are of high topological but low geometrical value and are used in negative screens to eliminate computationally derived structures that are chemically unreasonable. Large synthons are more restrictive geometrically and are used in positive screens ranking upward predicted structures that contain these more well-defined patterns. In the second stage, these screens are applied to CSP of nine new aminols carried out in 14 space groups. In each space group, up to 10 lowest energy structures were analyzed with respect to their synthon content. The results are encouraging, and the predictions were classified as good, unclear, or bad. Two predictions were verified with actual crystal structure determinations. 相似文献
100.
Along with the normally produced pulses of dI/dt, x-ray, optical emission, neutrons and ions by a Mather type plasma focus gun, one more set of pulses were observed to be
generated by a low energy device at Trombay, a few 100 ns after the first set of pulses, in majority of the discharges. In
a small number of discharges even three or more sets of pulses were observed. Signals from pick-up probes placed in the run
down region of the device suggest formation of more than one sheath which subsequently may form more than one focus which
in turn is responsible for the second and subsequent sets of pulses. 相似文献