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71.
Concern is growing over the contamination of the environment with pharmaceutical residues, among which non-steroidal anti-inflammatory
drugs (NSAIDs) are one of the most abundant groups. Their widespread appearance in the aquatic environment is because of their
high consumption and their incomplete removal during wastewater treatment. Because effective operation of wastewater-treatment
plants is important for minimising the release of xenobiotic compounds, for example pharmaceutical products, into the aquatic
environment, our study focuses on removal of commonly used NSAIDs (ibuprofen, naproxen, ketoprofen, diclofenac) and clofibric
acid in a specially designed small-scale pilot wastewater treatment plant (PWWTP). This study shows that, except for diclofenac,
steady-rate removal of NSAIDs over a two-year monitoring period has been achieved. Elimination of the compounds in the PWWTP
was ≥87% for ibuprofen, naproxen and ketoprofen but only 49–59% for diclofenac. We also studied clofibric acid. Results after
one month of operation revealed 30% elimination with no sign of adaptation by the biomass. Also described are degradation
products of diclofenac, which we were able to identify because of the similarity of their mass spectra with those in the NIST
library and by comparing the retention times of different compounds. Although the structures of these compounds were confirmed
with a high probability (99%), we still need to compare the fragmentation of authentic compounds with degradation products
formed under our experimental conditions. Degradation products of ibuprofen, naproxen, ketoprofen, and clofibric acid were
found but these must be identified by use of high-resolution mass spectrometry and analysis of authentic compounds. 相似文献
72.
Osswald P Struckmeier U Kasper T Kohse-Höinghaus K Wang J Cool TA Hansen N Westmoreland PR 《The journal of physical chemistry. A》2007,111(19):4093-4101
The influences of fuel-specific destruction pathways on flame chemistry are determined for two isomeric ester fuels, methyl acetate, CH3(CO)OCH3, and ethyl formate, H(CO)OC2H5, used as model representatives for biodiesel compounds, and their potential for forming air pollutants is addressed. Measurements are presented of major and intermediate species mole fractions in premixed, laminar flat flames using molecular-beam sampling and isomer-selective VUV-photoionization mass spectrometry. The observed intermediate species concentrations depend crucially on decomposition of the different radicals formed initially from the fuels. The methyl acetate structure leads to preferential formation of formaldehyde, while the ethyl formate isomer favors the production of acetaldehyde. Ethyl formate also yields higher concentrations of the C2 species (C2H2 and C2H4) and C4 species (C4H2 and C4H4). Benzene concentrations, while larger for ethyl formate, are at least an order of magnitude smaller for both flames than seen for simple hydrocarbon fuels (ethylene, ethane, propene, and propane). 相似文献
73.
Odaka TE Melnikov VV Jensen P Hirano T Lang B Langer P 《The Journal of chemical physics》2007,126(9):094301
The authors report here the implementation of a newly developed, highly efficient matrix diagonalization routine in the DR program [T. E. Odaka et al., J. Mol. Struct. 795, 14 (2006)]. The DR program solves the rovibronic Schrodinger equation for a triatomic molecule with a double Renner effect, i.e., with two accessible linear arrangements of the nuclei at which the electronic energy is doubly degenerate. With the new routines, the authors can extend the DR calculations of rovibronic energies for A 2Pi MgNC/MgCN by considering a much larger set of rovibronic states, in particular, states at higher J values, than the authors were able to access previously. 相似文献
74.
75.
Electroporation (EP) is one of the successful physical methods for intracellular drug delivery, which temporarily permeabilizes plasma membrane by exposing cells to electric pulses. Orientation of cells in electric field is important for electroporation and, consequently, for transport of molecules through permeabilized plasma membrane. Uptake of molecules after electroporation are the greatest at poles of cells facing electrodes and is often asymmetrical. However, asymmetry reported was inconsistent and inconclusive—in different reports it was either preferentially anodal or cathodal. We investigated the asymmetry of polar uptake of calcium ions after electroporation with electric pulses of different durations, as the orientation of elongated cells affects electroporation to a different extent when using electric pulses of different durations in the range of 100 ns to 100 µs. The results show that with 1, 10, and 100 µs pulses, the uptake of calcium ions is greater at the pole closer to the cathode than at the pole closer to the anode. With shorter 100 ns pulses, the asymmetry is not observed. A different extent of electroporation at different parts of elongated cells, such as muscle or cardiac cells, may have an impact on electroporation-based treatments such as drug delivery, pulse-field ablation, and gene electrotransfection. 相似文献
76.
77.
Daniel O'Nolan Haiyan Zhao Zhihengyu Chen Antonin Grenier Michelle L. Beauvais Mark A. Newton Tina M. Nenoff Peter J. Chupas Karena W. Chapman 《Chemical science》2021,12(41):13836
Unraveling the complex, competing pathways that can govern reactions in multicomponent systems is an experimental and technical challenge. We outline and apply a novel analytical toolkit that fully leverages the synchronicity of multimodal experiments to deconvolute causal from correlative relationships and resolve structural and chemical changes in complex materials. Here, simultaneous multimodal measurements combined diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and angular dispersive X-ray scattering suitable for pair distribution function (PDF), X-ray diffraction (XRD) and small angle X-ray scattering (SAXS) analyses. The multimodal experimental data was interpreted via multi-level analysis; conventional analyses of each data series were integrated through meta-analysis involving non-negative matrix factorization (NMF) as a dimensional reduction algorithm and correlation analysis. We apply this toolkit to build a cohesive mechanistic picture of the pathways governing silver nanoparticle formation in zeolite A (LTA), which is key to designing catalytic and separations-based applications. For this Ag-LTA system, the mechanisms of zeolite dehydration, framework flexing, ion reduction, and cluster and nanoparticle formation and transport through the zeolite are elucidated. We note that the advanced analytical approach outline here can be applied generally to multimodal experiments, to take full advantage of the efficiencies and self-consistencies in understanding complex materials and go beyond what can be achieved by conventional approaches to data analysis.Multimodal in situ experimental data probing a complex reaction have been integrated via a multi-level analysis involving non-negative matrix factorization and correlation analysis. This strategy can be applied generally to multimodal experiments. 相似文献
78.
Wolfgang Einholz Knut Vaas Christoph Wieloch Bernd Speiser Tina Wizemann Markus Strbele Hans‐Jürgen Meyer 《无机化学与普通化学杂志》2002,628(1):258-268
Chemical and Cyclovoltammetric Investigation of the Redoxreactions of the Decahalodecaborates closo ‐[B10X10]2– and hypercloso ‐[B10X10]· – (X = Cl, Br)1). Crystal Structure Analysis of Cs2[B10Br10] · 2 H2O The oxidation of the decachloro‐closo‐decaborates(2–) Cs2[B10Cl10] or [Me4N]2[B10Cl10] with Tl(CF3COO)3 leads to the corresponding radical monoanion hypercloso‐[B10Cl10] · –, which was characterized by ESR and UV/Vis spectroscopy. [B10Cl10] · – does not dimerize like [B10H10] · – but it is reduced by acetonitrile to the dianion [B10Cl10]2–. Cs2[B10Cl10] reacts with stronger oxidation agents like CoF3 (in dichloromethane) or XeF2 (in perfluorhexane), respectively, to yield B9Cl9 and, in traces, B8Cl8. In opposite to this, the decabromoderivative Cs2[B10Br10] does not show any reaction with Tl(CF3COO)3 in acetonitrile or with CoF3 in CH2Cl2. The oxidation of the dianions [B10X10]2– (X = Cl, Br) was studied by electroanalytical methods (cyclic voltammetry, chronoamperometry, chronocoulometry). Formal potentials were determined for the two steps of the reaction, which do not seem to be affected by structural rearrangements. The crystal structure of Cs2[B10Br10] · 2 H2O was analyzed by single‐crystal X‐ray diffraction. Cs2[B10Br10] · 2 H2O crystallizes monoclinic (space group I2/a, (no. 15), Z = 8, a = 1361.54(9) pm, b = 1215.89(5) pm, c = 3108.4(2) pm, α = 90°, β = 97.916(8)°, γ = 90°). The closo‐cluster B10Br102– has a bicapped square antiprismatic structure with idealized D4d symmetry. 相似文献
79.
80.
Li J Li WZ Huang W Cheung AW Bi CW Duan R Guo AJ Dong TT Tsim KW 《Journal of chromatography. A》2009,1216(11):2071-2078
A high-performance liquid chromatography coupled with diode array detector and mass spectrometry (HPLC-DAD-MS) method was developed to evaluate the quality of Rhizoma Belamcandae (Belamcanda chinensis (L.) DC.) through establishing chromatographic fingerprint and simultaneous determination of seven phenolic compounds. The analysis was achieved on an Alltima C(18) analytical column (250 mm x 4.6 mm i.d. 5 microm) using linear gradient elution of acetonitrile-0.1% trifluoroacetic acid. The correlation coefficients of similarity were determined from the HPLC fingerprints, and they shared a close similarity. By using an online APCI-MS/MS, twenty phenols were identified. In addition, seven of these phenols including mangiferin, 7-O-methylmangiferin, tectoridin, resveratrol, tectorigenin, irigenin and irisflorentin were quantified by the validated HPLC-DAD method. These phenols are considered to be major constituents in Rhizoma Belamcandae, and are generally regarded as the index for quality assessment of this herb. This developed method by having a combination of chromatographic fingerprint and quantification analysis could be applied to the quality control of Rhizoma Belamcandae. 相似文献