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981.
Martínez-Salvador S Forniés J Martín A Menjón B 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(29):8085-8097
The homoleptic, square‐planar organoplatinum(II) compound [NBu4]2[Pt(CF3)4] ( 1 ) undergoes oxidative addition of CF3I under mild conditions to give rise to the octahedral organoplatinum(IV) complex [NBu4]2[Pt(CF3)5I] ( 2 ). This highly trifluoromethylated species reacts with Ag+ salts of weakly coordinating anions in Me2CO under a wet‐air stream to afford the aquo derivative [NBu4][Pt(CF3)5(OH2)] ( 4 ) in around 75 % yield. When the reaction of 2 with the same Ag+ salts is carried out in MeCN, the solvento compound [NBu4][Pt(CF3)5(NCMe)] ( 5 ) is obtained in around 80 % yield. The aquo ligand in 4 as well as the MeCN ligand in 5 are labile and can be cleanly replaced by neutral and anionic ligands to furnish a series of pentakis(trifluoromethyl)platinate(IV) compounds with formulae [NBu4][Pt(CF3)5(L)] (L=CO ( 6 ), pyridine (py; 7 ), tetrahydrothiophene (tht; 8 )) and [NBu4]2[Pt(CF3)5X] (X=Cl ( 9 ), Br ( 10 )). The unusual carbonyl–platinum(IV) derivative [NBu4][Pt(CF3)5(CO)] ( 6 ) is thermally stable and has a νCO of 2194 cm?1. The crystal structures of 2? CH2Cl2, 5 , [PPh4][Pt(CF3)5(CO)] ( 6′ ), and 7 have been established by X‐ray diffraction methods. Compound 2 has shown itself to be a convenient entry to the chemistry of highly trifluoromethylated platinum compounds. To the best of our knowledge, compounds 2 and 4 – 10 are the organoelement compounds with the highest CF3 content to have been isolated and adequately characterized to date. 相似文献
982.
Perna FM Salomone A Dammacco M Florio S Capriati V 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(29):8216-8225
The employment of hexane/N,N,N',N'-tetramethylethylenediamine (TMEDA) dramatically hinders the racemization of those lithiated styrene oxides (trifluoromethyl-, chloro-, and phenylthio-substituted) that have been proven to be configurationally unstable in THF on the timescale of their reactions. The barriers to inversion and the activation parameters, calculated (Eyring equation) for reactions performed in THF, THF/TMEDA, and hexane/TMEDA, suggest the intervention of particular enantiomerization mechanisms for each case. The role of TMEDA in both coordinating and noncoordinating solvents has also been questioned and discussed in light of the kinetic data gathered and a model for deprotonation in hexane/TMEDA has also been proposed. The synthetic benefits of our results became apparent on establishing an asymmetric synthesis of an industrially important antifungal agent. 相似文献
983.
Geninatti-Crich S Alberti D Szabo I Deagostino A Toppino A Barge A Ballarini F Bortolussi S Bruschi P Protti N Stella S Altieri S Venturello P Aime S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(30):8479-8486
The upregulation of low-density lipoprotein (LDL) transporters in tumour cells has been exploited to deliver a sufficient amount of gadolinium/boron/ligand (Gd/B/L) probes for neutron capture therapy, a binary chemio-radiotherapy for cancer treatment. The Gd/B/L probe consists of a carborane unit (ten B atoms) bearing an aliphatic chain on one side (to bind LDL particles), and a Gd(III)/1,4,7,10-tetraazacyclododecane monoamide complex on the other (for detection by magnetic resonance imaging (MRI)). Up to 190 Gd/B/L probes were loaded per LDL particle. The uptake from tumour cells was initially assessed on cell cultures of human hepatoma (HepG2), murine melanoma (B16), and human glioblastoma (U87). The MRI assessment of the amount of Gd/B/L taken up by tumour cells was validated by inductively coupled plasma-mass-spectrometric measurements of the Gd and B content. Measurements were undertaken in vivo on mice bearing tumours in which B16 tumour cells were inoculated at the base of the neck. From the acquisition of magnetic resonance images, it was established that after 4-6 hours from the administration of the Gd/B/L-LDL particles (0.1 and 1 mmol kg(-1) of Gd and (10)B, respectively) the amount of boron taken up in the tumour region is above the threshold required for successful NCT treatment. After neutron irradiation, tumour growth was followed for 20 days by MRI. The group of treated mice showed markedly lower tumour growth with respect to the control group. 相似文献
984.
Alejandro Pati?o Cristina Canal Cristina Rodríguez Gabriel Caballero Antonio Navarro José Ma Canal 《Cellulose (London, England)》2011,18(4):1073-1083
The surface of cotton fabrics was functionalized through corona plasma treatments and/or by cationising the whole of the fibre
with an epihalohydrin. The effects of both treatments, individually and in combination are analyzed through wettability studies,
by X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), and also by dyeing studies with an hetero bis
functional reactive dye. Plasma improved wetting properties, exhaustion of the dyebaths and K/Scorr of the fabrics through surface functionalisation. Cationising of the cotton highly increased the exhaustion of the dyebaths
and produced a dramatic improvement in K/Scorr. Plasma treatment previous to cationising increased the impregnation of the fabrics, but the effects of both treatments on
dyeing parameters are additive only in column water rise and generally the effects obtained by cationising with the epihalohydrin
prevail. The differences between both treatments are discussed in terms of surface functionalisation of the cotton fibres. 相似文献
985.
Squeglia F Marchetti R Ruggiero A Lanzetta R Marasco D Dworkin J Petoukhov M Molinaro A Berisio R Silipo A 《Journal of the American Chemical Society》2011,133(51):20676-20679
Bacterial Ser/Thr kinases modulate a wide number of cellular processes. In Bacillus subtilis , the Ser/Thr kinase PrkC has been shown to induce germination of bacterial spores in response to DAP-type but not Lys-type cell wall muropeptides. Muropeptides are a clear molecular signal that growing conditions are promising, since they are produced during cell wall peptidoglycan remodeling associated with cell growth and division of neighboring bacteria. However, whether muropeptides are able to bind the protein physically and how the extracellular region is able to distinguish the two types of muropeptides remains unclear. Here we tackled the important question of how the extracellular region of PrkC (EC-PrkC) senses muropeptides. By coupling NMR techniques and protein mutagenesis, we exploited the structural requirements necessary for recognition and binding and proved that muropeptides physically bind to EC-PrkC through DAP-moiety-mediated interactions with an arginine residue, Arg500, belonging to the protein C-terminal PASTA domain. Notably, mutation of this arginine completely suppresses muropeptide binding. Our data provide the first molecular clues into the mechanism of sensing of muropeptides by PrkC. 相似文献
986.
Li FF Rodríguez-Fortea A Poblet JM Echegoyen L 《Journal of the American Chemical Society》2011,133(8):2760-2765
Electrochemically generated Lu(3)N@I(h)-C(80) dianions react with the electrophile, PhCHBr(2), to produce a methano derivative of Lu(3)N@I(h)-C(80)(CHC(6)H(5)) (1) with high regioselectivity. The compound was characterized by MALDI-TOF, NMR, and UV-vis-NIR absorption spectroscopy. Electrochemical characterization of this Lu(3)N@I(h)-C(80)(CHC(6)H(5)) derivative showed the typical irreversible reductive behavior of the pristine Lu(3)N@I(h)-C(80), similar to those observed for Bingel adducts of Lu(3)N@I(h)-C(80). Using the same conditions, the reaction between Sc(3)N@I(h)-C(80) dianions and PhCHBr(2) was conducted for comparison. Unexpectedly, no nucleophilic reaction was observed, indicating that Sc(3)N@I(h)-C(80) dianions are not reactive toward the electrophile. Theoretical studies for both dianionic Lu(3)N@I(h)-C(80) and Sc(3)N@I(h)-C(80) showed that the HOMO is more highly localized on the fullerene cage for [Lu(3)N@I(h)-C(80)](2-) and more localized on the inside cluster for [Sc(3)N@I(h)-C(80)](2-), providing an explanation for the drastically different reactivities observed. 相似文献
987.
Lucía Molina-García Antonio Ruiz-Medina María Luisa Fernández-de Córdova 《Analytica chimica acta》2011,(2):226
For the first time, a spectrofluorimetric method is reported for the simultaneous determination of resveratrol (RVT) and piceid (PCD), two stilbenes showing diverse interesting physiological and biochemical attributes, as well as a wide range of health benefits ranging from cardioprotection to chemoprevention. The method makes use of a multicommutated flow-through optosensor in which the resolution of RVT and PCD is accomplished by means the sequential arrival of their photoproducts, on-line generated by UV-irradiation, to the detection area. This is possible due to the different kinetic behaviour of these latter on a solid support (C18 silica gel) filling a minicolumn placed before the detector. The measurement in solid-phase of the photochemically induced fluorescence of the photoproducts (λex: 257 nm/λem: 382 nm) is used as analytical signal for monitoring both compounds. The method has been applied to the analysis of RVT and PCD in wines and requires a previous solid-phase extraction (SPE) using Bakerbond C18 cartridges. This pretreatment and the use of a solid-support in both the minicolumn and the flow-cell of the detector allow the determination of RVT and PCD by external calibration. Detection limits (DLs) are 9.3 and 12.6 ng mL−1 for RVT and PCD, respectively. Commercial red and white wine samples have been analysed and the results obtained have been satisfactorily validated by high-performance liquid chromatography (HPLC). 相似文献
988.
Érika C. D’Anton Reipert Christianne E.C. Rodrigues Antonio J.A. Meirelles 《The Journal of chemical thermodynamics》2011,43(12):1784-1790
Deacidification of vegetable oils can be performed using liquid–liquid extraction as an alternative method to the classical chemical and physical refining processes. This paper reports experimental data for systems containing refined babassu oil, lauric acid, ethanol, and water at 303.2 K with different water mass fractions in the alcoholic solvent (0, 0.0557, 0.1045, 0.2029, and 0.2972). The dilution of solvent with water reduced the distribution coefficient values, which indicates a reduction in the loss of neutral oil. The experimental data were used to adjust the NRTL equation parameters. The global deviation between the observed and the estimated compositions was 0.0085, indicating that the model can accurately predict the behavior of the compounds at different levels of solvent hydration. 相似文献
989.
Antonio Doménech María Teresa Doménech‐Carbó Trinidad Pasies María Carmen Bouzas 《Electroanalysis》2011,23(12):2803-2812
An operational modification of Tafel analysis, applied to the intermediate region of square wave voltammetric curves, devoted to the identification of corrosion products on archaeological metal, is described. This is based on the voltammetry of microparticles methodology using conventional abrasive conditioning of the electrode, as well as ‘one‐touch’ and layer‐by‐layer techniques. The proposed methodology is applied to the identification of copper and silver corrosion products in mediaeval silver‐copper coins from the Libertad street hoard in Valencia (Spain). 相似文献
990.
Teresa Galeano‐Díaz María‐Isabel Acedo‐Valenzuela Nielene Mora‐Diez Antonio Silva‐Rodríguez 《Electroanalysis》2011,23(2):449-455
A method, using stripping differential pulse voltammetry, for the simultaneous determination of Imipramine and its metabolite Desipramine is reported. Both compounds produce, at glassy carbon electrode, an electrochemical signal due to an adsorptive‐oxidative process. The voltammograms show a very high overlap degree between IM and DE peaks. The multivariate calibration method PLS‐1 was employed for the simultaneous determination of both compounds. An experimental design together with the response surface methodology has been used to find the optimum experimental conditions. The developed procedure has been utilized in the analysis of fortified human serum samples with good recovery values for each analyte. 相似文献