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251.
Joy Chakraborty Brajagopal Samanta Guillaume Pilet Samiran Mitra 《Structural chemistry》2006,17(6):585-593
A new hydrogen-bonded polymeric Mn(III) complex C19H20Mn1N3O3S1 (1) has been synthesised by conventional procedure with a new Schiff base ligand (2Z,3Z)-N
1,N
2-bis(1-(2-hydroxyphenyl)ethylidene)ethane-1,2-diamine (H
2
L) bearing a tetradentate N2O2 donor site. The complex has been characterised with several spectroscopic techniques like FT-IR, UV/Vis and EPR and also
well supported by variable temperature magnetic susceptibility study. The structure of the co-ordination complex has been
unequivocally confirmed from single crystal X-ray diffraction study. The redox stability of the metal chelate complex has
been investigated with a slow scan cyclic voltammetry. 相似文献
252.
A novel, facile and inexpensive solid phase extraction (SPE) method using ethylene glycol bis-mercaptoacetate modified 3-(trimethoxysilyl)-1-propanethiol grafted Fe3O4 nanoparticles coupled with spectrofluorimetric detection was proposed for determination of aflatoxin M1 (AFM1) in liquid milk samples. The method uses the advantage fluorescence enhancement by β-cyclodexterin complexation of AFM1 in 12% (v/v) acetonitrile–water and the remarkable properties of Fe3O4 nanoparticles namely high surface area and strong magnetization were utilized to achieve high enrichment factor (57) and satisfactory extraction recoveries (91–102%) using only 100 mg of magnetic adsorbent. Furthermore, fast separation time of about 15 min avoids many time-consuming column-passing procedures of conventional SPE. The main factors affecting extraction efficiency including pH value, desorption conditions, extraction/desorption time, sample volume, and adsorbent amount were evaluated and optimized. Under the optimal conditions, a wide linear range of 0.04–8 ng mL−1 with a low detection limit of 0.015 ng mL−1 was obtained. The developed method was applied for extraction and preconcentration of AFM1 in three commercially available milk samples and the results were compared with the official AOAC method. 相似文献
253.
High Resolution Scanning Tunneling Microscopy of a 1D Coordination Polymer with Imidazole‐Based N,N,O Ligands on HOPG 下载免费PDF全文
Dr. Nina V. Fischer Utpal Mitra Karl‐Georg Warnick Dr. Viacheslav Dremov Dr. Michael Stocker Thorsten Wölfle Dr. Wolfgang Hieringer Dr. Frank W. Heinemann Prof. Dr. Nicolai Burzlaff Prof. Dr. Andreas Görling Prof. Dr. Paul Müller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(37):11863-11869
Novel κ3‐N,N,O ligands tend to form 1D coordination polymer strands. Deposition of 1D structures on highly oriented pyrolytic graphite (HOPG) was achieved from diluted solutions and polymer strands have been studied on HOPG by AFM/STM. Single strands were mapped by STM and their electronic properties were subsequently characterized by current imaging tunneling spectroscopy (CITS). Periodic density functional calculations simulating a polymer strand deposited on a HOPG surface are in agreement with the zig‐zag structure indicated by experimental findings. Both the observed periodicity and the Zn–Zn distances can be reproduced in the simulations. Van der Waals interactions were found to play a major role for the geometry of the isolated polymer strand, for the adsorption geometry on HOPG, as well as for the adsorption energy. 相似文献
254.
Debabrata Chatterjee Anannya Mitra Bidhan Chandra Roy 《Reaction Kinetics and Catalysis Letters》2000,70(1):147-151
A novel mixed-ligand [RuIII(amp)(pic)(H2O)] complex (1) (H2amp = N-(hydroxyphenyl)salicyldimine; pic = picolinate) has been synthesized and characterized by physico-chemical methods. Complex 1has been found to be an effective catalyst in oxo-functionalization of C-H bond of organic substrates by using tert-butyl hydroperoxide (t-BuOOH) as a terminal oxidant. Formation of a high valent Ru(V)-oxo species as catalytic intermediate is proposed to be the source of oxygen atom in the oxidised product. 相似文献
255.
Saha Manas Kumar Sen Sutapa Gupta Tarakranjan Mitra Samiran Kundu Parimal Karmakar Aswini Kumar 《Transition Metal Chemistry》1998,23(5):635-640
The mononuclear fragments [Cu(HDopn)(OH)2]+ and [Cu(HPopn)(OH)2]+, [H2Dopn=3,3-(trimethylene- dinitrilo)-dibutan-2–one dioximate and H2Popn, = 3, 3-(phenylenedinitrilo)-dibutan-2–one dioximate] were used to prepare four binuclear complexes [(OH2)Cu (Dopn)Cu(ditn)]2+, [(OH2)Cu(Dopn)Ni(ditn)(H2O)]2+ (ditn=diethylenetriamine) and [(OH2)Cu(Popn)Cu(L) (H2O)]2+ (L=2,2-bipyridine or 1,10–phenanthroline). Two trinuclear complexes, [{Cu(Popn)(OH2)}2M (H2O)n]2+ (when M=CuII, n=1; M=ZnII, n= 2), have been synthesised and characterised by elemental analyses, f.a.b. mass, i.r., electronic, e.s.r. spectroscopy and variable temperature (5–300K) magnetic susceptibility measurements. A strong antiferromagnetic interaction (J=–545cm–1 to –700cm–1) has been found for the binuclear copper(II) complexes. The X-band e.s.r. spectra of these complexes at 300K and for trinuclear complexes at 120K indicate square-pyramidal geometry for the copper centres with a (dx2–y2)1 ground state. The binuclear complex of copper(II)–nickel(II) centres with antiferromagnetic interaction (J=–107 cm–1) is described, and moderately strong zero-field splitting within the quartet state leads to Kramers doublet, as indicated by X-band e.s.r. spectra of this complex. The trinuclear copper(II) complex with an antiferromagnetic interaction (J= –350cm–1) is also described. The heterometallic trinuclear copper(II)–zinc(II)–copper(II) system shows a very weak interaction (J–1cm–1). 相似文献
256.
Supported liquid membrane microextraction (SLMME) with high-performance liquid chromatography (HPLC)-UV detection has been developed for the extraction, preconcentration, and determination of all the nine haloacetic acids (HAAs) in water. The HAAs are extracted into a supported liquid membrane, and then back-extracted into few microliters of an acceptor solution. The extract was directly analyzed by HPLC-UV with a 15-min run. Enrichment factors in the range of 300-3000 were obtained in a 60-min extraction, and detection limits were at low to sub-microg/L level with R.S.D. values between 1.5 and 10.8%. The parameters that affected analyte enrichment were studied. This approach offers an attractive alternative to the current US Environmental Protection Agency standard methods for HAA analysis, which require complex sample preparation and derivatization prior to analysis by gas chromatography. SLMME can also be used in conjunction with other analytical schemes, such as, ion chromatography and capillary electrophoresis. 相似文献
257.
Subhankar Tripathi 《Tetrahedron》2004,60(23):4959-4965
Functionalized furanose-fused piperidines 4-6 and oxazepines 15-17, useful precursors for structurally unique bioactive nucleosides as well as for potential glycosidase inhibitors, have been synthesized by the application of 1,3-dipolar azide cycloaddition (DAC) reaction on d-glucose based substrates. The strategy works well even with the nucleoside analogue 8, affording the bicyclic nucleoside analogues 11 and 12. 相似文献
258.
Pritha Talukder Shyamapada ShitAshok Sasmal Stuart R. BattenBoujemaa Moubaraki Keith S. MurraySamiran Mitra 《Polyhedron》2011,30(11):1767-1773
A novel hexanuclear complex [{(CuL)2Cu}2(μ-dca)2](ClO4)2·2L′(1) (where H2L = (OH)C6H4C(CH3)N(CH2)3NC(CH3)C6H4(OH) or N,N′-bis(2-hydroxyacetophenone) propylenediimine and dca = N(CN)2− and L′ = 2-hydroxyacetophenone) has been synthesized and characterized by elemental analysis, UV-Vis, FT-IR spectroscopic and electrochemical methods. Single crystal X-ray structural characterization reveals a centrosymmetric nature of the complex unit, where the metal centers adopt distorted square-planar and distorted octahedral geometries. Structural analysis also reveals μ2-phenoxo bridges between terminal and the central copper(II) centers of the asymmetric [(CuL)2Cu(dca)] unit, the latter being interconnected to its symmetry related counterpart by double μ1,5-dca bridges, leading to the hexanuclear complex ion [{(CuL)2Cu}2(μ-dca)2]2+. Low temperature susceptibility measurements of 1 revealed the presence of strong antiferromagnetic coupling (2J = −407 cm−1) between the copper(II) centers. 相似文献
259.
We designed and fabricated microfluidic devices with serpentine separation channels and asymmetrically tapered turns, thus allowing high efficiency separations and minimizing band broadening associated with the “racetrack” effect. We evaluated the performance of these devices by measuring the variation in separation efficiency with separation length, electric field strength, taper ratio of the turns, and number of turns. N‐Glycans derived from ribonuclease B and labeled with 8‐aminopyrene‐1,3,6‐trisulfonic acid were electrophoretically separated on serpentine channels with separation lengths of 11, 18, 22, and 36 cm at electric field strengths from 750 to 1750 V/cm. Separations on the 36‐cm channel produced plate numbers up to 940 000 with an analysis time under 3.1 min, whereas separations on the 22‐cm channel had a shorter analysis time (less than 1.25 min), still with respectable efficiencies (up to 600 000 plates). Turn‐induced dispersion was minimized with taper ratios 2 and 3, whereas having two or four 180° turns along with the separation length did not impact the overall efficiency. The developed device was used to analyze native and desialylated N‐glycans derived from the blood serum of an ovarian cancer patient and a disease‐free individual. Separation efficiencies similar to that achieved with the model glycans from ribonuclease B were attained for these biological samples. 相似文献
260.