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121.
Two new iridoid glucosides 1 and 2, 10-O-(3, 4-dimethoxy-(E)-cinnamoyl)catalpol and 10-O-(3, 4-dimethoxy-(Z)-cinnamoyl)catalpol, were isolated from Lagotis yunnanensis. Their structures were elucidated by spectroscopic methods. 相似文献
122.
Counter-current chromatography (CCC) is a form of liquid–liquid partition chromatography. It requires two immiscible solvent phases; the stationary phase is retained in the separation column, generally by centrifugal force, while the mobile phase is eluted. We recently replaced the mobile phase with supercritical fluid carbon dioxide (SF CO2). Since the solvent strength of SF CO2 can be varied by changing the temperature and pressure of the system, separation adjustments are thus more versatile. We investigated the pressure and temperature effects on resolution using water and low-carbon alcohol mixtures as the stationary phases. It was demonstrated that these special properties of SF CO2 were indeed beneficial to the optimization of separations. In addition, the phase retention ratio was examined in terms of separation resolution. The results appeared very similar to those obtained from conventional traditional CCC. This study should be helpful for the future development of SF applications in CCC. 相似文献
123.
M.?Mahendra B.?H.?Doreswamy M.?A.?Sridhar J.?Shashidhara?PrasadEmail author S.?A.?Khanum S.?Shashikanth T.?D.?Venu 《Journal of chemical crystallography》2005,35(6):463-467
The crystal structure of the title compound, C21H16O3, has been determined. The compound crystallizes in triclinic space group PĪ with cell parameters a = 9.2240(9) Å, b = 9.8050(8) Å, c = 10.1610(11) Å, α = 94.749(6)∘, β = 112.544(4)∘, γ = 102.145(6)∘ and Z = 2. The structure exhibits both intra and intermolecular interactions of the type C–H ⋅s O. The intermolecular interaction between the molecules form centrosymmetric dimers. 相似文献
124.
This study presents a new HPLC method using evaporative light scattering detection for the simultaneous determination of live major iridoid glucosides, namely 7-epi-loganin, sweroside, loganin, 7-epi-vogeloside, and secoxyloganin in Flos Lonicerae, an important traditional Chinese medicinal herb. The optimal conditions of separation and detection were achieved on a C18 analytical column with an isocratic mobile phase consisting of methanol-water (30:70, v/v) containing 0.5% acetic acid at the flow-rate of 1.0 ml/min, temperature for the detector drift tube set at 90 degrees C and the nitrogen flow-rate of 2.6 l/min. The limit of detection (S/N = 3) is less than 35.1 microg/ml and the limit of quantification (S/N = 10) is less than 140.1 microg/ml. All calibration curves show good linear regression (r2>0.996) within test ranges. This method provides good reproducibility for the quantification of the major iridoid glucosides in four Lonicera species with overall intra- and inter-day variation of less than 5% and 9%, respectively. The assay was successfully applied to quantify the main iridoid glucosides in the herb and to identify the botanical origin of Flos Lonicerae. 相似文献
125.
İhsan Çalış Ayşegül Güvenç Metin Armağan Mehmet Koyuncu Charlotte H. Gotfredsen Søren R. Jensen 《Helvetica chimica acta》2007,90(8):1461-1466
From the aerial parts of Eremostachys moluccelloides Bunge , a new iridoid glucoside, lamalbidic acid ( 7 ), was isolated as its choline salt 7a together with six known iridoid glucosides, 5‐deoxysesamoside ( 1 ), 6β‐hydroxy‐7‐epiloganin ( 2 ), lamalbide ( 3 ), shanzhiside methyl ester ( 4 ), sesamoside ( 5 ), and 5‐deoxypulchelloside I ( 6 ). The structures of 7a and 7 (obtained from 7a ) were elucidated by spectroscopic (UV, IR, 1D‐ and 2D‐NMR, and ESI‐MS) methods. 相似文献
126.
Polyiodide complexes of benzophenone (B) with iodine (I) and alkali iodide (MI, M = Na, K, Rb or Cs) have been prepared from methanol for the first time. The crystals of these complexes (abbreviated BIMI) are in the shape of hexagonal prisms with golden luster sides and black cross sections. BIMI complexes exhibit semiconductive behavior from 250 to 310 K with activation energies of 0.6 to 0.8 eV. Under an applied dc field at room temperature, the longitudinal conductivity of BIMI crystals is in the order of 10?6 Scm?1 and does not decrease over a period of half an hour, indicating no ionic conductivity in these complexes. In contrast, significant ionic conductivity is observed for benzophenone complexes grown from chloroform. It is concluded that the solvent molecules play an important role in determining the electrical behavior of the resulting benzophenone complexes. The results of conductivity and resonance Raman spectroscopic studies on the entire methanol series of BIMI complexes suggest that a common conduction pathway is probably provided by the polyiodide chains in this new series of benzophenone complexes. 相似文献
127.
Chang‐Yan Sun Dr. Xin‐Xin Li Shui‐Feng Wang Wen‐Jun Li Xiang‐Jun Zheng 《无机化学与普通化学杂志》2008,634(5):950-955
Four new transition metal coordination polymers, [Co(bpndc)(phen)(H2O)]n ( 1 ), [Co3(bpndc)3(2,2′‐bpy)2]n·0.5n(i‐C3H7OH) ( 2 ), and [M(bpndc)(2,2′‐bpy)2]n (M = Zn, 3 ; Cu, 4 ; H2bpndc = benzophenone ‐4,4′‐dicarboxylic acid; phen = 1,10‐phenanthroline; 2,2′‐bpy = 2,2′‐bipyridine) have been synthesized by the hydrothermal reactions and characterized by single crystal X‐ray diffraction, elemental analysis, and IR spectrum. Because of the introduction of different terminal auxiliary ligands, bpndc ligands in complexes 1 and 2 adopt different coordination modes. In complex 1 , bpndc ligands act as tridentate ligand and bridge CoII ions into 1D double‐stranded chains; while complex 2 possesses 2D (4,4) grids, where bpndc ligands adopt tetradente and pentadentate modes. Two such grids interpenetrate to form a novel catenane‐like layer. Complexes 3 and 4 are isostructural. Bpndc ligands adopt tetradentate mode and bridge metal ions forming 1D helical chains. 相似文献
128.
Manjula Singh Arvind K. Yadav Lal Dhar S. Yadav R.K.P. Singh 《Tetrahedron letters》2017,58(23):2206-2208
We report herein a simple, metal- and oxidant-free visible light promoted strategy for an anti-Markovnikov hydrothiolation of unactivated olefins using benzophenone as an inexpensive photocatalyst at room temperature. Anti-Markovnikov adducts of a wide variety of olefins and thiols are formed in highly regioselective manner and good to excellent yields. The present radical thiol-ene reaction is operationally simple and well tolerates a variety of functional groups. 相似文献
129.
Zhen Fan Jing Jin Chaozhan Lin Chenchen Zhu Tao Yang Bao Yang Jinping Zhu Zhongxiang Zhao 《Helvetica chimica acta》2015,98(1):108-115
Three new flavanol glycosides, 1 – 3 , and eight known compounds, 4 – 11 , were isolated from a MeOH extract of the fern Abacopteris aspera (Presl ) Ching . Their structures were elucidated on the basis of extensive spectroscopic analysis, including HSQC, HMBC, 1H,1H‐COSY, and NOESY experiments, acid hydrolysis, and by the comparison of their NMR data with those of related compounds. 相似文献
130.
Double dispersant‐assisted ionic liquid dispersive liquid–liquid microextraction coupled with capillary electrophoresis for the determination of benzophenone‐type ultraviolet filters in sunscreen cosmetic product 下载免费PDF全文
In this work, double dispersant‐assisted ionic liquid dispersive liquid–liquid microextraction coupled with micellar electrokinetic chromatography was developed to determine four UV filters (benzophenone, 4‐hydroxybenzophenone, 2,4‐dihydroxybenzophenone, and 2‐hydroxy‐4‐methoxybenzophenone). 1‐Hexyl‐3‐methylimidazolium hexafluorophosphate was used as the extraction solvent. The main novelty of the present work was that acetonitrile‐Triton X‐114 was used as double disperser solvent. Parameters affected the extraction efficiency were investigated and optimized. Under the optimum conditions, enrichment factors were in the range of 25.3?40.5. The limits of detection and quantitation, calculated at a S/N of three and ten, were 3.9?6.7 ng/mL and 13.0?22.3 ng/mL. The linearity of the method was in the range of 0.02?2 μg/mL for 2, 4‐dihydroxybenzophenone and 4‐hydroxybenzophenone, 0.01?2 μg/mL for benzophenone and 2‐hydroxy‐4‐methoxybenzophenone, with correlation coefficient (R2) of 0.9984?0.9991. The proposed method was successfully applied to the determination of four benzophenone‐type UV filters in six kinds of sunscreen cosmetic products, with yielded relative recoveries ranging from 80.2 to 117.7%. 相似文献