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991.
An oxacalix[2]arene[2]pyrimidine-bis(ZnII-porphyrin) conjugate was readily prepared via nucleophilic aromatic substitution of a phenolic AB3-Zn-porphyrin on the upper rim of a (1,3-alternate) 5,17-bis(methylsulfonyl)oxacalix[4]arene precursor. Efficient 1:1 complex formation between the ‘jaws’ bisporphyrin tweezer and fullerene C70 was evidenced by 1H NMR titrations (K = 3.0 × 104 M−1), while no detectable complexation could be observed with C60. On the other hand, an analogous oxacalix[4]arene-bis(Cu-corrole) conjugate did not show any measurable (C60 or C70) fullerene binding. 相似文献
992.
Nico Smit Ruben Musson Fred Romijn Huub Van Rossum Johannes Van Pelt 《Photochemistry and photobiology》2010,86(2):360-366
Calcineurin (Cn) is the target of immunosuppressive drugs used for maintenance therapy of transplant patients. UV radiation is also known to be immunosuppressive and, like the Cn inhibitors, UV has been shown to positively influence various inflammatory skin diseases. Recently, Cn activity has been demonstrated in skin and skin cell cultures. In the present study we have investigated the effects of UV(A-1) irradiation on Cn activity in skin. In total skin we found a significant reduction in Cn activity after exposure to 450 kJ m−2 of UVA-1 (340–400 nm). In repeated experiments cultures of fibroblasts and keratinocytes also showed dose-dependent and selective reduction in Cn activity after UVA-1 irradiation. UVB irradiation caused a decrease in the Cn activity of one of two fibroblast cultures and was ineffective in keratinocytes. In Jurkat cells and PBMC UVA-1 reduced Cn activity and also the production of cytokines such as interleukin (IL)-2, γ-interferon, IL-4 and IL-10 that are controlled by the Ca2+–Cn pathway. These results indicate that UV(A-1) irradiation may lead to inactivation of Cn in the skin and thus suppress the skin immune system in a similar fashion to the Cn inhibitors. 相似文献
993.
V.A. Sethuraman M.J. Chon M. Shimshak N. Van Winkle P.R. Guduru 《Electrochemistry communications》2010,12(11):1614-1617
We report in situ measurement of biaxial moduli of a Si thin-film electrode as a function of its lithium concentration. During lithiation, biaxial compressive stress is induced in the Si film and it undergoes plastic flow. At any state-of-charge (SOC), a relatively small delithiation–relithiation sequence unloads and reloads the film elastically. From the stress and strain changes during a delithiation–relithiation cycle, the biaxial modulus of the film is calculated. Stress change is obtained by measuring the change in substrate curvature using a Multi-beam Optical Sensor; the elastic strain change is obtained from the change in SOC. By repeating these measurements at several different values of SOC, the biaxial modulus was seen to decrease from ca. 70 GPa for Li0.32Si to ca. 35 GPa for Li3.0Si. Such a significant reduction in elastic modulus has important implications for modeling stress evolution and mechanical degradation in Si-based anodes. 相似文献
994.
H-shaped bridged oligothiophenes HT-1 and HT-2 were synthesized by two different approaches. Different from normal oligothiophenes, HT-1 and HT-2 showed low band gaps and amphoteric redox behaviors due to intramolecular charge transfer, which is further supported by time-dependent DFT calculations. 相似文献
995.
Tim De Meyer Davy Sinnaeve Bjorn Van Gasse Ernst-R Rietzschel Marc L. De Buyzere Michel R. Langlois Sofie Bekaert José C. Martins Wim Van Criekinge 《Analytical and bioanalytical chemistry》2010,398(4):1781-1790
Proton nuclear magnetic resonance (1H-NMR)-based metabolomics enables the high-resolution and high-throughput assessment of a broad spectrum of metabolites in
biofluids. Despite the straightforward character of the experimental methodology, the analysis of spectral profiles is rather
complex, particularly due to the requirement of numerous data preprocessing steps. Here, we evaluate how several of the most
common preprocessing procedures affect the subsequent univariate analyses of blood serum spectra, with a particular focus
on how the standard methods perform compared to more advanced examples. Carr–Purcell–Meiboom–Gill 1D 1H spectra were obtained for 240 serum samples from healthy subjects of the Asklepios study. We studied the impact of different
preprocessing steps—integral (standard method) and probabilistic quotient normalization; no, equidistant (standard), and adaptive-intelligent
binning; mean (standard) and maximum bin intensity data summation—on the resonance intensities of three different types of
metabolites: triglycerides, glucose, and creatinine. The effects were evaluated by correlating the differently preprocessed
NMR data with the independently measured metabolite concentrations. The analyses revealed that the standard methods performed
inferiorly and that a combination of probabilistic quotient normalization after adaptive-intelligent binning and maximum intensity
variable definition yielded the best overall results (triglycerides, R = 0.98; glucose, R = 0.76; creatinine, R = 0.70). Therefore, at least in the case of serum metabolomics, these or equivalent methods should be preferred above the
standard preprocessing methods, particularly for univariate analyses. Additional optimization of the normalization procedure
might further improve the analyses. 相似文献
996.
Gary S. Groenewold Wibe A. de Jong Jos Oomens Michael J. Van Stipdonk 《Journal of the American Society for Mass Spectrometry》2010,21(5):719-727
Tris-carboxylate complexes of uranyl [UO2]2+ with acetate and benzoate were generated using electrospray ionization mass spectrometry, and then isolated in a Fourier
transform ion cyclotron resonance mass spectrometer. Wavelength-selective infrared multiple photon dissociation (IRMPD) of
the tris-acetato uranyl anion resulted in a redox elimination of an acetate radical, which was used to generate an IR spectrum that
consisted of six prominent absorption bands. These were interpreted with the aid of density functional theory calculations
in terms of symmetric and antisymmetric −CO2 stretches of the monodentate and bidentate acetate, CH3 bending and umbrella vibrations, and a uranyl O—U—O asymmetric stretch. The comparison of the calculated and measured IR
spectra indicated that the predominant conformer of the tris-acetate complex contained two acetate ligands bound in a bidentate fashion, while the third acetate was monodentate. In similar
fashion, the tris-benzoate uranyl anion was formed and photodissociated by loss of a benzoate radical, enabling measurement of the infrared
spectrum that was in close agreement with that calculated for a structure containing one monodentate and two bidentate benzoate
ligands. 相似文献
997.
E. I. Zhilyaeva V. N. Semkin E. I. Yudanova R. M. Vlasova S. A. Torunova A. M. Flakina G. A. Mousdis K. V. Van A. Graja A. Lapinski R. B. Lyubovskii R. N. Lyubovskaya 《Russian Chemical Bulletin》2010,59(7):1360-1368
New conducting radical cation salts (EDT-TTF)3Hg 2Br6, (TMET) 5Hg(SCN) 4-xIx (x≈0.35), and (EDT-TTF)3Hg(SCN)3I0.5(PhCl)0.5 were synthesized. Their conductivities, ESR and polarized reflectance spectra were studied. It was shown that the organic conductors with differently oriented conducting layers (EDT-TTF)3Hg2Br6 and (TMET)5Hg(SCN)4-xIx (x≈?0.35) are characterized by the quasi-one-dimensional character of electron motion. The conductivity along and across conducting layers has a semiconductive character. It was established by ESR and polarized reflectance spectroscopy that the properties of such conductors are a superposition of the properties of individual conducting layers. 相似文献
998.
Annelien Deneckere Walter Schudel Marina Van Bos Helena Wouters Anna Bergmans Peter Vandenabeele Luc Moens 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(2):511-519
X-ray fluorescence spectroscopy (XRF) and Raman spectroscopy have been used to examine 15th century mediaeval and 16th century renaissance vault paintings in the Our Lady's Cathedral (Antwerp, Belgium) in view of their restoration. The use of mobile instruments made it possible to work totally non-destructively. This complementary approach yields information on the elemental (XRF) and on the molecular composition (Raman) of the pigments. For the 15th century vault painting the pigments lead–tin yellow (Pb2SnO4), lead white (2PbCO3·Pb(OH)2), vermilion (HgS), massicot (PbO) and azurite (2CuCO3·Cu(OH)2) could be identified. The pigments used for the 16th century vault painting could be identified as red lead (Pb3O4), hematite (Fe2O3), lead white (2PbCO3·Pb(OH)2) and azurite (2CuCO3·Cu(OH)2). For both paintings the presence of the strong Raman scatterer calcite (CaCO3) resulted in a difficult identification of the pigments by Raman spectroscopy. The presence of gypsum (CaSO4·2H2O) on the mediaeval vault painting probably indicates that degradation took place. 相似文献
999.
Volker Leen Dr. Wenwu Qin Prof. Dr. Wensheng Yang Jie Cui Chan Xu Xiaoliang Tang Dr. Weisheng Liu Prof. Dr. Koen Robeyns Dr. Luc Van Meervelt Prof. David Beljonne Prof. Dr. Roberto Lazzaroni Prof. Dr. Claire Tonnelé Noël Boens Prof. Wim Dehaen Prof. 《化学:亚洲杂志》2010,5(9):2016-2026
Starting from the conformationally unconstrained compound 3,5‐di‐(2‐bromophenoxy)‐4,4‐difluoro‐8‐(4‐methylphenyl)‐4‐bora‐3a,4a‐diaza‐s‐indacene ( 1 ), two BODIPY dyes ( 2 and 3 ) with increasingly rigid conformations were synthesized in outstanding total yields through palladium catalyzed intramolecular benzofuran formation. Restricted bond rotation of the phenoxy fragments leads to dyes 2 and 3 , which absorb and fluoresce more intensely at longer wavelengths relative to the unconstrained dye 1 . Reduction of the conformational flexibility in 2 and 3 leads to significantly higher fluorescence quantum yields compared to those of 1 . X‐ray diffraction analysis shows the progressively more extended planarity of the chromophore in line with the increasing conformational restriction in the series 1 → 2 → 3 , which explains the larger red shifts of the absorption and emission spectra. These conclusions are confirmed by quantum chemical calculations of the lowest electronic excitations in 1 , 1a , 2 , 2a , 3 and dyes of related chemical structures. The effect of the molecular structure on the visible absorption and fluorescence emission properties of 1 , 1a , 2 , 2a , 3 has been examined as a function of solvent by means of the new, generalized treatment of the solvent effect (J. Phys. Chem. B 2009 , 113, 5951–5960). Solvent polarizability is the primary factor responsible for the small solvent‐dependent shifts of the visible absorption and fluorescence emission bands of these dyes. 相似文献
1000.
Van Zyla RL Seatlholof ST Van Vuuren SF Viljoen A 《Natural product communications》2010,5(9):1381-1386
Complex interactions between numerous components of essential oils often contribute to the pharmacological effect and therapeutic outcome. To further elucidate these interactions, several essential oil constituents (EOCs) were combined in different ratios and their inhibitory effects on the growth of bacteria and yeast determined using the minimum inhibitory concentration (MIC) microplate assay. When combined and tested against Candida albicans, (+)-beta-pinene interacted antagonistically with (-)-menthone (sigmaFIC(T) = 9.80), but synergistically with 1,8-cineole (sigmaFIC(T) = 0.35). Against Escherichia coli, the combination of E- and Z-(+/-)-nerolidol and geranyl acetate displayed an additive interaction (sigmaFIC(T) = 1.04); while a variable interaction was observed between E- and Z-(+/-)-nerolidol and eugenol with antagonism and synergy being observed at different ratios of each EOC. The combination of either carvacrol or eugenol with an antimicrobial agent (ciprofloxacin or amphotericin B) resulted in synergistic interactions against all microorganisms tested. These favourable results further support the use of essential oil constituents as adjuvants in the development of a new generation of phytopharmaceuticals that can be used in combination with synthetic drugs against drug-resistant microorganisms. 相似文献