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101.
Development of a Simple and Fast Electrochemical Method for Screening and Stoichiometric Determination of Dimenhydrinate 下载免费PDF全文
Jhonys Machado Freitas Thiago da Costa Oliveira Polyana Luiza Silva Denise Tofanello Gimenes Rodrigo Alejandro Abarza Munoz Eduardo Mathias Richter 《Electroanalysis》2014,26(9):1905-1911
Dimenhydrinate (DIM) is a salt composed by the combination of two active pharmaceutical ingredients: diphenhydramine (DIP) and 8‐chlorotheophylline (CTP). In this work, the use of batch injection analysis with multiple pulse amperometric detection (BIA‐MPA) was proposed for the first time for fast stoichiometric determination of DIM. DIP (cation) and CTP (anion) were determined simultaneously in pharmaceutical samples with a simple and fast injection procedure (70 injections h?1). Additional strategies were also proposed for rapid screening of samples containing the DIM salt. By a simple injection of a sample into the BIA system (without using of calibration curve), reliable information about stoichiometry of the DIM salt (1 : 1; DIP:CTP) and presence or absence of interfering species (electroactive) can be achieved. 相似文献
102.
Control of the Electronic Ground State on an Electron‐Transfer Copper Site by Second‐Sphere Perturbations 下载免费PDF全文
Marcos N. Morgada Dr. Luciano A. Abriata Ulises Zitare Dr. Damian Alvarez‐Paggi Prof. Daniel H. Murgida Prof. Alejandro J. Vila 《Angewandte Chemie (International ed. in English)》2014,53(24):6188-6192
The CuA center is a dinuclear copper site that serves as an optimized hub for long‐range electron transfer in heme–copper terminal oxidases. Its electronic structure can be described in terms of a σu* ground‐state wavefunction with an alternative, less populated ground state of πu symmetry, which is thermally accessible. It is now shown that second‐sphere mutations in the CuA containing subunit of Thermus thermophilus ba3 oxidase perturb the electronic structure, which leads to a substantial increase in the population of the πu state, as shown by different spectroscopic methods. This perturbation does not affect the redox potential of the metal site, and despite an increase in the reorganization energy, it is not detrimental to the electron‐transfer kinetics. The mutations were achieved by replacing the loops that are involved in protein–protein interactions with cytochrome c, suggesting that transient protein binding could also elicit ground‐state switching in the oxidase, which enables alternative electron‐transfer pathways. 相似文献
103.
Highly Enantioselective Construction of Tricyclic Derivatives by the Desymmetrization of Cyclohexadienones 下载免费PDF全文
Sandra del Pozo Dr. Alejandro Parra Dr. Sergio Díaz‐Tendero Dr. Rubén Mas‐Ballesté Dr. Silvia Cabrera Dr. José Alemán 《Angewandte Chemie (International ed. in English)》2014,53(31):8184-8189
The asymmetric synthesis of tricyclic compounds by the desymmetrization of cyclohexadienones is presented. The reaction tolerated a large variety of substituents at different positions of the cyclohexadienone, and heterocyclic rings of different sizes were accessible. Density functional theory calculations showed that the reaction proceeds through an asynchronous [4+2] cycloaddition. 相似文献
104.
Inside Cover: Quinone‐Rich Poly(dopamine) Magnetic Nanoparticles for Biosensor Applications (ChemPhysChem 17/2014) 下载免费PDF全文
105.
Susana Araceli Carrizales Álvarez Anna Ilyina Karla Monzerratt Gregorio Jáuregui José Luis Martínez Hernández Brenda Berenice Vazquez Gutiérrez Elda Patricia Segura Ceniceros Alejandro Zugasti Cruz Hened Saade Caballero Raúl Guillermo López Campos 《Applied biochemistry and biotechnology》2014,174(5):1945-1958
Avian influenza viruses preferentially bind to sialic acid alpha-2,3-galactose (N-SA-α-2,3-Gal) receptors on epithelial cells. Herein, we describe a procedure we have developed for isolation of N-SA-α-2,3-Gal receptors from porcine trachea using magnetic nanoparticles (NPs) coated with chitosan (NP-Ch) and functionalized with Maackia amurensis lectin (NP-lectin). Magnetic nanoparticles were coated with chitosan in a one-step co-precipitation, and then M. amurensis lectin was immobilized covalently using glutaraldehyde. Lectin coated nanoparticles were incubated with sialic acid enriched fraction of tracheal homogenate, and N-SA-α-2,3-Gal receptor was extracted under magnetic field in two cycles. The presence of 66.4 kDa protein was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The interaction of immobilized receptor (NP-Ch-R) with M. amurensis lectin (NP-Ch-R-L) was demonstrated by Fourier transform infrared spectrometry (FTIR) and thermogravimetric analysis (TGA). 相似文献
106.
Michele Cacioppo Tobias Scharl Dr. Luka Đorđević Dr. Alejandro Cadranel Dr. Francesca Arcudi Prof. Dirk M. Guldi Prof. Maurizio Prato 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(31):12879-12884
Carbon dots (CDs) and their derivatives are useful platforms for studying electron-donor/acceptor interactions and dynamics therein. Herein, we couple amorphous CDs with phthalocyanines (Pcs) that act as electron donors with a large extended π-surface and intense absorption across the visible range of the solar spectrum. Investigations of the intercomponent interactions by means of steady-state and pump-probe transient absorption spectroscopy reveal symmetry-breaking charge transfer/separation and recombination dynamics within pairs of phthalocyanines. The CDs facilitate the electronic interactions between the phthalocyanines. Thus, our findings suggest that CDs could be used to support electronic couplings in multichromophoric systems and further increase their applicability in organic electronics, photonics, and artificial photosynthesis. 相似文献
107.
Jennifer Paola Hernández Mancera Francisco Núñez-Zarur Soledad Gutiérrez-Oliva Alejandro Toro-Labbé Ricardo Vivas-Reyes 《Journal of computational chemistry》2020,41(23):2022-2032
Quantum chemical calculations were used to study the mechanism of Diels-Alder reactions involving chiral anthracenes as dienes and a series of dienophiles. The reaction force analysis was employed to obtain a detailed scrutiny of the reaction mechanisms, it has been found that thermodynamics and kinetics of the reactions are quite consistent: the lower the activation energy, the lower the reaction energy, thus following the Bell-Evans-Polanyi principle. It has been found that activation energies are mostly due to structural rearrangements that in most cases represented more than 70% of the activation energy. Electronic activity mostly due to changes in σ and π bonding were revealed by the reaction electronic flux (REF), this property helps identify whether changes on σ or π bonding drive the reaction. Additionally, new global indexes describing the behavior of the electronic activity were introduced and then used to classify the reactions in terms of the spontaneity of their electronic activity. Local natural bond order electronic population analysis was used to check consistency with global REF through the characterization of specific changes in the electronic density that might be responsible for the activity already detected by the REF. Results show that reactions involving acetoxy lactones are driven by spontaneous electronic activity coming from bond forming/strengthening processes; in the case of maleic anhydrides and maleimides it appears that both spontaneous and non-spontaneous electronic activity are quite active in driving the reactions. 相似文献
108.
109.
Dr. Reiko Ueoka Dr. Roy A. Meoded Alejandro Gran-Scheuch Dr. Agneya Bhushan Prof. Dr. Marco W. Fraaije Prof. Dr. Jörn Piel 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(20):7835-7839
Bacterial trans-acyltransferase polyketide synthases (trans-AT PKSs) are multimodular megaenzymes that biosynthesize many bioactive natural products. They contain a remarkable range of domains and module types that introduce different substituents into growing polyketide chains. As one such modification, we recently reported Baeyer–Villiger-type oxygen insertion into nascent polyketide backbones, thereby generating malonyl thioester intermediates. In this work, genome mining focusing on architecturally diverse oxidation modules in trans-AT PKSs led us to the culturable plant symbiont Gynuella sunshinyii, which harbors two distinct modules in one orphan PKS. The PKS product was revealed to be lobatamide A, a potent cytotoxin previously only known from a marine tunicate. Biochemical studies show that one module generates glycolyl thioester intermediates, while the other is proposed to be involved in oxime formation. The data suggest varied roles of oxygenation modules in the biosynthesis of polyketide scaffolds and support the importance of trans-AT PKSs in the specialized metabolism of symbiotic bacteria. 相似文献
110.
Alejandro Cervantes-Reyes Dr. Frank Rominger Prof. Dr. A. Stephen K. Hashmi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(24):5530-5540
The synthesis and full characterization of new air-stable AgI and CuI complexes bearing structurally bulky expanded-ring N-heterocyclic carbene (erNHC) ligands is presented. The condensation of protonated NHC salts with Ag2O afforded a collection of AgI complexes, and their first use as ligand transfer reagents led to novel isostructural CuI or AuI complexes. In situ deprotonation of the NHC salts in the presence of a copper(I) source, provides a library of new CuI complexes. The solid-state structures feature large N-CNHC-N angles (118–128°) and almost identical angles between the aryl groups on the nitrogen atoms and the plane of the N-C-N unit of the carbene (i.e. torsion angles close to 0°). Among the steric parameters, the percent buried volume (%Vbur) values span easily in the 50–57 % range, and that one of (9-Dipp)CuBr complex (%Vbur=57.5) overcomes to other known erNHC–metal complexes reported to date. Preliminary catalytic experiments in the copper-catalyzed coupling between N-tosylhydrazone and phenylacetylene, afforded 76–93 % product at the 0.5–2.5 mol % catalyst loading, proving the stability of CuI erNHC complexes at elevated temperatures (100 °C). 相似文献