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241.
Martinelli JR Watson DA Freckmann DM Barder TE Buchwald SL 《The Journal of organic chemistry》2008,73(18):7102-7107
A method for the Pd-catalyzed carbonylation of aryl bromides has been developed using Xantphos as the ligand. This method is effective for the direct synthesis of Weinreb amides, primary and secondary benzamides, and methyl esters from the corresponding aryl bromides at atmospheric pressure. In addition, a putative catalytic intermediate, (Xanphos)Pd(Br)benzoyl, was prepared and an X-ray crystal structure was obtained revealing an unusual cis-coordination mode of Xantphos in this palladium-acyl complex. 相似文献
242.
Jean-Cyrille Hierso David Evrard Dominique Lucas Philippe Richard Hélène Cattey Bernard Hanquet Philippe Meunier 《Journal of organometallic chemistry》2008,693(3):574-578
From the analysis of several nickel and palladium halide complexes of a constrained ferrocenyl tetraphosphine, the existence in solution phase of unique 31P-31P “through-space” nuclear spin-spin coupling constants (JPP) had been previously evidenced. Due to the blocked conformation of the species in solution, and based on the NMR spectra obtained for the complexes and their corresponding solid state X-ray structures, these JPP constants had been shown to clearly depend on the mutual spatial position of the corresponding phosphorus atoms. Herein, the quantitative correlation disclosed at that time (P?P distance dependence of coupling constants) is remarkably confirmed, and mathematically refined owing to the study of a new palladium dibromide tetraphosphine complex, for which the synthesis and the solution NMR and solid state X-ray characterizations are reported. 相似文献
243.
Boulinguiez B Le Cloirec P Wolbert D 《Langmuir : the ACS journal of surfaces and colloids》2008,24(13):6420-6424
The selection of a proper sorbent for a given application is a complex problem. The design and efficiency of adsorption processes require an equilibrium adsorption model. Linear transformation is one of the methods available to estimate the adjustable parameters of isotherm models but possesses limitations compared to nonlinear regressions. A different approach to calculate predicted equilibrium isotherm values leading to an alternative nonlinear regression is presented in this paper and compared with usual regression methods. Adsorption isotherm data of gaseous THT onto three activated carbon materials constitute an experimental basis for the discussion. Assessment of the goodness-of-fit of the Langmuir model is supported by different selected test functions. The new nonlinear approach did not obtain the best results for each test function, but raises questions about the inherent combined error in regression procedures. 相似文献
244.
Vahl K Kahlert H Böttcher D Wardenga R Komorsky-Lovrić S Bornscheuer U Scholz F 《Analytica chimica acta》2008,610(1):44-49
Potentiometric FIA titrations were performed to determine enzyme activities of lipase type B from Candida antarctica, CAL-B. Two substrates, triacetin and tributyrin were hydrolyzed in phosphate buffer solutions, and the concentration change of the base component of the buffer was titrated in a carrier solution containing hydrochloric acid and potassium chloride. The system was calibrated with butyric acid and acetic acid, respectively. FIA titration peaks were evaluated with respect to peak height and peak area. Butyric acid and acetic acid could be titrated in the buffer solution from 3 × 10−3 mol L−1 to 0.1 mol L−1. The detection limit of enzyme activity was determined to be 0.07 U mL−1 (15 min reaction time) and the minimum activity was calculated to be 0.035 units corresponding to 35 nmol min−1. The specific activities of lipase B for the hydrolysis of tributyrin and triacetin were determined as 16 ± 2 U mg−1 and 2 ± 0.2 U mg−1 (per mg commercial lipase preparation), respectively. 相似文献
245.
Dr. Matthieu Jouffroy Prof. Dr. Dominique Armspach Prof. Dr. Dominique Matt Prof. Dr. Kohtaro Osakada Dr. Daisuke Takeuchi 《Angewandte Chemie (International ed. in English)》2016,55(29):8367-8370
Cationic PdII monophosphine complexes derived from α‐ and β‐cyclodextrins (CDs) promote the homopolymerization of styrene under carbon monoxide pressure. Although reversible CO coordination takes place under catalytic conditions according to 13C NMR studies with 13C‐enriched CO, both complexes catalyze the formation of CO‐free styrene polymers. These macromolecules display optical activity as a result of the presence of stereoregular sequences within the overall atactic polymer. 相似文献
246.
Diego Cattaruzza Nabil Absi Dominique Feillet 《4OR: A Quarterly Journal of Operations Research》2016,14(3):223-259
This paper presents a survey on the multi-trip vehicle routing problem (MTVRP) and on related routing problems where vehicles are allowed to perform multiple trips. The first part of the paper focuses on the MTVRP. It gives an unified view on mathematical formulations and surveys exact and heuristic approaches. The paper continues with variants of the MTVRP and other families of routing problems where multiple trips are sometimes allowed. For the latter, it specially insists on the motivations for having multiple trips and the algorithmic consequences. The expected contribution of the survey is to give a comprehensive overview on a structural property of routing problems that has seen a strongly growing interest in the last few years and that has been investigated in very different areas of the routing literature. 相似文献
247.
Kurusch Ebrahimi-Fard Dominique Manchon Johannes Singer 《Letters in Mathematical Physics》2016,106(3):365-380
We consider a particular one-parameter family of q-analogues of multiple zeta values. The intrinsic q-regularisation permits an extension of these q-multiple zeta values to negative integers. Renormalised multiple zeta values satisfying the quasi-shuffle product are obtained using an Hopf-algebraic Birkhoff factorisation together with minimal subtraction. 相似文献
248.
María Abreu-Sepúlveda Dominique E. Williams Ashfia Huq Chetan Dhital Yunchao Li M. Parans Paranthaman Karim Zaghib A. Manivannan 《Ionics》2016,22(3):317-325
Titanium, tantalum-substituted Li7La3Zr2-xAxO12 (LLZO, A?=?Ta, Ti) garnets, and chromium-substituted La(2/3)-xLi3xTi1-yCryO3 (LLTO) perovskites were prepared by a conventional solid-state reaction and the Pechini processes. The desired crystal phases were obtained by varying the calcination temperature and time, as well as the substitution concentration. All samples indicated decomposition of the precursors when heated above 750 °C and formation of the desired phase after heat treatment at higher temperatures. Neutron diffraction data shows the formation of a predominant cubic phase in the case of Ta-LLZO, and monoclinic phase with minor impurity phases for Cr-LLTO. Ionic conductivity for Ti-LLZO (Li7La3Zr1.4Ti0.6O12), Ta-LLZO (Li6.03La3Zr1.533Ta0.46O12), and Cr-LLTO (La(2/3)-xLi3xTi0.9Cr0.1O3) at room temperature were found to be 5.21?×?10?6, 1.01?×?10?6, and 1.2?×?10?4 S cm?1, respectively. The activation energies of the compounds were determined from the Arrhenius plot and were 0.44 eV (Ti0.6-LLZO), 0.54 eV (Ta0.5-LLZO), and 0.20 eV (Cr0.1-LLTO). 相似文献
249.
250.
Binder WH Sachsenhofer R Farnik D Blaas D 《Physical chemistry chemical physics : PCCP》2007,9(48):6435-6441
The present paper investigates the selective incorporation of preformed nanoparticles (hydrophobic Au-NP (2 nm); hydrophilic Au-NP (12 nm); hydrophobic CdSe-NP (1.9 nm); retrovirus-particles (approximately 30 nm)) into the interface of lipid vesicles and polymersomes via TEM and DLS investigations. Lipid membranes were made from N,N-dimethyl-N,N-dioctadecylammonium bromide (DODAB), di-oleoyl-phosphatidylcholine (DOPC), whereas polymersome-membranes were fabricated from the diblock copolymer poly-(butadiene-block-ethylenoxide). Stabilization of the final structures was achieved via sol/gel processes at the outside of the membranes, thus stabilizing the structure by a silicate shell. Whereas hydrophobic Au-NPs can be successfully embedded into the polymersome- and lipid-vesicle membranes, hydrophilic nanoparticles were found evenly distributed in the inner- and outer compartments of the vesicles and polymersomes. Significant effects such as size reduction, selective enrichment of all nanoparticles within only few polymersomes as well as budding effects of larger entities (i.e., viral particles) are described. 相似文献