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991.
Carla Estivill Albert Virgili Eva Monteagudo Francisco Sánchez-Ferrando Juan F. Piniella 《Tetrahedron》2009,65(1):171-8937
A new chiral diamine with low basicity was synthesized in enantiopure form. (1R,1′R)-1,1′-(Anthracene-9,10-diyl)bis(2,2,2-trifluoroethanamine) was obtained by means of several stereochemically controlled reactions. The structures of the title compound and several intermediates were studied. 相似文献
992.
This study demonstrates the surface modification of thermally expandable core/shell microspheres by grafting glycidyl methacrylate (GMA) using activators regenerated by electron transfer (ARGET) ATRP. To retain the expansion properties it was essential to minimize the shear forces, use solvents compatible with the microspheres and keep the reaction times short (three hours or less). Using microspheres with hydroxyl groups on the surface, it was found that after converting these to α-bromo esters, GMA could be grafted by ARGET ATRP using only 50 ppm of copper catalyst in toluene at 30 °C. Decent control of the polymerization was achieved with PMDETA as ligand reaching PDIs of 1.4 for the solution polymerization of GMA. When microspheres were present, the polymerization was less controlled with higher PDIs. The epoxide groups of the grafted microspheres were hydrolyzed by HCl in THF providing a hydrophilic surface of the microsphere. The expansion property of the microspheres was studied after each reaction step by thermal mechanical analysis, and it was found that the expansion capacity was well preserved with only limited negative effect on the microspheres. 相似文献
993.
Phthalocyanines (Pc), which are peripherally substituted with pyridin-3-yloxy groups, have shown promise as sensitizers for photodynamic cancer therapy (PDT). Some aza-analogues (AzaPc) are reported here. Four monomers were synthesized, i.e. 5,6-di(pyridin-3-yloxy)pyrazine-2,3-dicarbonitrile, and three pyrazine-2,3-dicarbonitriles, substituted with pyridin-3-yloxy- in combination with H, Me and Ph groups. Cyclotetramerizations of these monomers with the reagent Zn(quinoline)2Cl2 yielded the targeted ZnAzaPcs in 20–40% yields.The cyclotetramerizations were accompanied, and apparently initiated, by complexation between zinc(II) and the pyridin-3-yloxy groups attached to the pyrazine-dicarbonitriles. Two such zinc(II) complexes were isolated and characterized. Identifications of all new substances were primarily based on NMR spectra, where the pulse techniques COSY, NOESY, HSQC and HMBC were applied. Molecular ions of the ZnAzaPcs were determined by mass spectrometry (MALDI-TOF). The UV–Vis spectra of these macrocycles were as expected, with Q-band absorptions at 630–650 nm and molar extinction coefficients, ε, 70 000–100 000. Eight peripheral pyridin-3-yloxy groups induced a small blue shift of the Q-band, from 636 nm for unsubstituted ZnAzaPc, to 630 nm, whereas a red shifted Q-band at 650 nm resulted from the combination of phenyl and pyridin-3-yloxy substituents. Improved solubilities were observed for the unsymmetrical ZnAzaPcs compared to octa(pyridin-3-yloxy)ZnAzaPc. 相似文献
994.
Victoria L. Blair Luca M. Carrella William Clegg Prof. Jan Klett Dr. Robert E. Mulvey Prof. Dr. Eva Rentschler Prof. Dr. Luca Russo Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(4):856-863
With the aim of introducing the diisopropylamide [NiPr2] ? ligand to alkali‐metal‐mediated manganation (AMMMn) chemistry, the temperature‐dependent reactions of a 1:1:3 mixture of butylsodium, bis(trimethylsilylmethyl)manganese(II), and diisopropylamine with ferrocene in hexane/toluene have been investigated. Performed at reflux temperature, the reaction affords the surprising, ferrocene‐free, hydrido product [Na2Mn2 (μ‐H)2{N(iPr)2}4]?2 toluene ( 1 ), the first Mn hydrido inverse crown complex. Repeating the reaction rationally, excluding ferrocene, produces 1 in an isolated crystalline yield of 62 %. At lower temperatures, the same bimetallic amide mixture leads to the manganation of ferrocene to generate the first trimanganese, trinuclear ferrocenophane, [{Fe(C5H4)2}3{Mn3Na2(NiPr2)2 (HNiPr2)2}] ( 2 ) in an isolated crystalline yield of 81 %. Both 1 and 2 have been characterised by X‐ray crystallographic studies. The magnetic properties of paramagnetic 1 and 2 have also been examined by variable‐temperature magnetisation measurements on powdered samples. For 1 , the room‐temperature value for χT is 3.45 cm3 K mol?1, and on lowering the temperature a strong antiferromagnetic coupling between the two Mn ions is observed. For 2 , the room‐temperature value for χT is 4.06 cm3 K mol?1, which is significantly lower than the expected value for three isolated paramagnetic MnII ions. 相似文献
995.
Teresa García-Valderrama Eva Mulero-MendigorriDaniel Revuelta-Bordoy 《European Journal of Operational Research》2009
The objective of this article is to propose a framework for analysis of the relationships between the four perspectives of the balanced scorecard (BSC) of Kaplan and Norton. To this end, several different models of efficiency have been developed, utilising data envelopment analysis (DEA). Each of the variables has been extracted from a model of the BSC for research and development (R&D) activities. A study has been carried out with 90 companies to illustrate a case of this analysis. 相似文献
996.
A method for solving geodesic equations in Schwarzschild–de Sitter space–times and higher dimensional Schwarzschild space–times is presented. The solutions are derived from Jacobi's inversion problem on a Riemann surface of genus 2 restricted to the set of zeros of the theta function, which is called a theta–divisor. In its final form, the solutions are given in terms of derivatives of Kleinian sigma functions. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
997.
Emma Rossinyol Eva Pellicer Anna Prim Sònia Estradé Jordi Arbiol Francesca Peiró Albert Cornet Joan Ramon Morante 《Journal of nanoparticle research》2008,10(2):369-375
Highly crystalline and thermally stable gadolinium doped ceria (GDC) particles have been synthesized by hard template route
for the first time. This oxide is being recognized as an intermediate temperature (500–700 °C) electrolyte material for applications
in solid-oxide fuel cells. The GDC particles show high crystallinity and nanometric size (2.83 ± 0.05 nm in diameter) and
Raman analyses confirm the formation of the solid solution instead of a CeO2 and Gd2O3 mixture. EDX and EELS studies indicate a stoichiometry coherent with the Gd0.2Ce0.8O1.9 phase. The synthesized nanometric powder is expected to be used in solid oxide fuel cells as well as in the catalytic treatment
of automobile exhaust fumes.
Graphical abstract相似文献
998.
999.
Aizpurua JM Sagartzazu-Aizpurua M Monasterio Z Azcune I Mendicute C Miranda JI García-Lecina E Altube A Fratila RM 《Organic letters》2012,14(7):1866-1868
Mesoionic 4,4'-bis(1,2,3-triazole-5,5'-diylidene) Rh(I) complexes having a C2 chiral 4,4'-axis were accessed from 3-alkyltriazolium salts in virtually complete de. Their structure and configurational integrity were assessed by NMR spectroscopy, X-ray crystallography, and chiral HPLC. Computational analysis of the MICs involved in the reaction suggested the formation of a highly stable and unprecedented cation-carbene intermediate species, which could be evidenced experimentally by cyclic voltammetry analysis. 相似文献
1000.
B Andreasen DM Tanenbaum M Hermenau E Voroshazi MT Lloyd Y Galagan B Zimmernann S Kudret W Maes L Lutsen D Vanderzande U Würfel R Andriessen R Rösch H Hoppe G Teran-Escobar M Lira-Cantu A Rivaton GY Uzunoğlu DS Germack M Hösel HF Dam M Jørgensen SA Gevorgyan MV Madsen E Bundgaard FC Krebs K Norrman 《Physical chemistry chemical physics : PCCP》2012,14(33):11780-11799
The present work is the fourth (and final) contribution to an inter-laboratory collaboration that was planned at the 3rd International Summit on Organic Photovoltaic Stability (ISOS-3). The collaboration involved six laboratories capable of producing seven distinct sets of OPV devices that were degraded under well-defined conditions in accordance with the ISOS-3 protocols. The degradation experiments lasted up to 1830 hours and involved more than 300 cells on more than 100 devices. The devices were analyzed and characterized at different points of their lifetimes by a large number of non-destructive and destructive techniques in order to identify specific degradation mechanisms responsible for the deterioration of the photovoltaic response. Work presented herein involves time-of-flight secondary ion mass spectrometry (TOF-SIMS) in order to study chemical degradation in-plane as well as in-depth in the organic solar cells. Various degradation mechanisms were investigated and correlated with cell performance. For example, photo-oxidation of the active material was quantitatively studied as a function of cell performance. The large variety of cell architectures used (some with and some without encapsulation) enabled valuable comparisons and important conclusions to be drawn on degradation behaviour. This comprehensive investigation of OPV stability has significantly advanced the understanding of degradation behaviour in OPV devices, which is an important step towards large scale application of organic solar cells. 相似文献