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11.
Separation of cannabinoids on three different mixed‐mode columns containing carbon/nanodiamond/amine‐polymer superficially porous particles
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Chuan‐Hsi Hung Janusz Zukowski David S. Jensen Andrew J. Miles Clayton Sulak Andrew E. Dadson Matthew R. Linford 《Journal of separation science》2015,38(17):2968-2974
Three mixed‐mode high‐performance liquid chromatography columns packed with superficially porous carbon/nanodiamond/amine‐polymer particles were used to separate mixtures of cannabinoids. Columns evaluated included: (i) reversed phase (C18), weak anion exchange, 4.6 × 33 mm, 3.6 μm, and 4.6 × 100 mm, 3.6 μm, (ii) reversed phase, strong anion exchange (quaternary amine), 4.6×33 mm, 3.6 μm, and (iii) hydrophilic interaction liquid chromatography, 4.6 × 150 mm, 3.6 μm. Different selectivities were achieved under various mobile phase and stationary phase conditions. Efficiencies and peak capacities were as high as 54 000 N/m and 56, respectively. The reversed phase mixed‐mode column (C18) retained tetrahydrocannabinolic acid strongly under acidic conditions and weakly under basic conditions. Tetrahydrocannabinolic acid was retained strongly on the reversed phase, strong anion exchange mixed‐mode column under basic polar organic mobile phase conditions. The hydrophilic interaction liquid chromatography column retained polar cannabinoids better than the (more) neutral ones under basic conditions. A longer reversed phase (C18) mixed‐mode column (4.6 × 100 mm) showed better resolution for analytes (and a contaminant) than a shorter column. Fast separations were achieved in less than 5 min and sometimes 2 min. A real world sample (bubble hash extract) was also analyzed by gradient elution. 相似文献
12.
[Cu32(H)20{S2P(OiPr)2}12]: The Largest Number of Hydrides Recorded in a Molecular Nanocluster by Neutron Diffraction
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Dr. Rajendra S. Dhayal Jian‐Hong Liao Dr. Samia Kahlal Dr. Xiaoping Wang Dr. Yu‐Chiao Liu Dr. Ming‐Hsi Chiang Prof. Werner E. van Zyl Prof. Jean‐Yves Saillard Prof. C. W. Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(23):8369-8374
An air‐ and moisture‐stable nanoscale polyhydrido copper cluster [Cu32(H)20{S2P(OiPr)2}12] ( 1H ) was synthesized and structurally characterized. The molecular structure of 1H exhibits a hexacapped pseudo‐rhombohedral core of 14 Cu atoms sandwiched between two nestlike triangular cupola fragments of (2×9) Cu atoms in an elongated triangular gyrobicupola polyhedron. The discrete Cu32 cluster is stabilized by 12 dithiophosphate ligands and a record number of 20 hydride ligands, which were found by high‐resolution neutron diffraction to exhibit tri‐, tetra‐, and pentacoordinated hydrides in capping and interstitial modes. This result was further supported by a density functional theory investigation on the simplified model [Cu32(H)20(S2PH2)12]. 相似文献
13.
Inside Back Cover: A Reversible Proton Relay Process Mediated by Hydrogen‐Bonding Interactions in [FeFe]Hydrogenase Modeling (Chem. Eur. J. 31/2015)
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Kiran Kumarvarma Chakrahari Rhone P. Brocha Silalahi Tzu‐Hao Chiu Xiaoping Wang Nadia Azrou Samia Kahlal Yu‐Chiao Liu Ming‐Hsi Chiang Jean‐Yves Saillard C. W. Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(15):4997-5001
The structurally precise Cu‐rich hydride nanoclusters [PdCu14H2(dtc/dtp)6(C≡CPh)6] (dtc: di‐butyldithiocarbamate ( 1 ); dtp: di‐isopropyl dithiophosphate ( 2 )) were synthesized from the reaction of polyhydrido copper clusters [Cu28H15(S2CNnBu2)12]+ or [Cu20H11{S2P(OiPr)2}9] with phenyl acetylene in the presence of Pd(PPh3)2Cl2. Their structures and compositions were determined by single‐crystal X‐ray diffraction and the results supported by ESI‐mass spectrometry. Hydride positions in 1 were confirmed by single‐crystal neutron diffraction. Each hydride is connected to one Pd0 and four CuI atoms in slightly distorted trigonalbipyramidal geometry. The anatomies of clusters 1 and 2 are very similar and DFT calculations allow rationalizing the interactions between the encapsulated [PdH2]2? unit and its Cu14 bicapped icosahedral cage. As a result, Pd has the highest coordination number (14) so far recorded. 相似文献
16.
Redox Communication within Multinuclear Iron–Sulfur Complexes Related to Electronic Interplay in the Active Site of [FeFe]Hydrogenase
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Kai‐Ti Chu Dr. Yu‐Chiao Liu Yi‐Lan Huang Dr. Gene‐Hsiang Lee Dr. Mei‐Chun Tseng Prof. Ming‐Hsi Chiang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(18):6852-6861
The one‐electron oxidations of a Fe2 complex lead to the formation of a persistent metal‐stabilized thiyl radical Fe2 species, mixed‐valent Fe4, and Fe8 complexes. The unpaired spin in the Fe2 radical species delocalizes over the Fe2 and the aromatic dithiolate, mostly on the terminal sulfur. The subsequent dimerization of the singly oxidized Fe2 to the Fe4 retains the partial thiyl radical character. For an analogue with less steric hindrance, the π–π stacking interaction between the dithiolato aromatic rings induces generation of the Fe8, in which process electronic structures of the species are modulated through reducing the thiyl radical to the thiolate. Electronic reorganization repeats when the Fe8 is converted to Fe4. Electronic interplay in the complexes decreases the energy gap of frontier MOs and buffers electronic impacts upon redox events. Easier accessible redox potentials and increased stability of the species are facilitated. The results demonstrate that electronic versatility of the benzenedithiolate exerts pronounced influences on electronic and coordination structure of the metal complexes. 相似文献
17.
Anion‐Directed Copper(II) Metallocages,Coordination Chain,and Complex Double Salt: Structures,Magnetic Properties,EPR Spectra,and Density Functional Study
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Prof. Dr. Jing‐Yun Wu Ming‐Shiou Zhong Prof. Dr. Ming‐Hsi Chiang Dr. Dibyendu Bhattacharya Yen‐Wei Lee Prof. Dr. Long‐Li Lai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(21):7238-7247
A series of CuII metallo‐assemblies showing anion‐directed structural variations, including five metallocages [(Gn?)?{Cu2(Hdpma)4}](8?n)+(A?)8?n (Gn?=NO3?, ClO4?, SiF62?, BF4?, SO42?; A?=NO3?, ClO4?, BF4?, CH3SO4?; Hdpma=bis(3‐pyridylmethyl)ammonium cation), a complex double salt, namely, (H3dpma)4(CuCl4)5Cl2, and a coordination chain, namely, [Cu2(dpma)(OAc)4], are reported. The influence of the anion can be explained by its coordinating ability, the affinity of which for the CuII center interferes significantly with metallocage formation, and its shape, which offers host–guest recognition ability to engage in weak metal–anion coordination and hydrogen bonding to the organic ligand, which are responsible for metallocage templation. EPR studies of these metallocages in the powder phase at room temperature and 77 K showed a trend of the g values (g||>2.10>g⊥>2.00) indicating a ‐based ground state with square‐pyramidal geometry for the CuII centers. The magnetism of these metallocages can be interpreted as the result of a combination of relatively small magnetic coupling integrals and a substantial contribution of temperature‐independent paramagnetism (TIP). The weak magnetic interaction is corroborated by the results of DFT calculations and the EPR spectra. Availability of the low‐lying state for spin population was confirmed by a magnetization study, which revealed a magnetic moment approaching 2Nβ, which would explain the presence of the larger TIP term. 相似文献
18.
ABSTRACT An analytical computer simulation procedure for dynamic modeling of low-contact-ratio spur gear systems is presented. The procedure computes the gear static transmission error and uses a Fast Fourier Transform (FFT) to generate its frequency spectrum at various tooth profile modifications. The dynamic loading response of an unmodified (perfect involut) gear pair is compared with that of gears with profile modifications. Correlations are found between several profile modifications and the resulting dynamic loads. An effective error, obtained from frequency domain anal 相似文献
19.
Wan‐Ling Liu Yi‐Fen Hsu Yu‐Wei Liu Brenda Singco Ssu‐Wei Chen Hsi‐Ya Huang Ting‐Yu Chin 《Electrophoresis》2012,33(19-20):3008-3011
In this study, a rapid and sensitive method is described for the catecholamines detection in rat brain. CE with LIF detection for the determination of FITC derivatized catecholamines (dopamine, epinephrine, and norepinephrine) was demonstrated. Conventional water bath and microwave‐assisted derivatization methods were employed and a significant reduction in the derivatization time from 2 h for the conventional water bath at room temperature (ca. 25°C) to 2 min for the microwave‐assisted derivatization was achieved. Online sample concentration of field‐amplified sample stacking (FASS) method was employed to achieve higher sensitivities (the detection limits obtained in the normal injection mode ranged from 2.6 to 4.5 ng L?1 and in the FASS mode ranged from 22 to 34 pg L?1). Furthermore, this microwave‐assisted derivatization CE–LIF method successfully determined catecholamines in rat brain with as low as 100 ng L?1 (FASS mode) to 10 μg L?1 (normal injection mode). This CE–LIF method provided better detection ability when compared to the best reports on catecholamines analyses. 相似文献
20.
A biologically active peptide designated hLCP has been isolated and purified to homogeneity from human lung carcinoma by means of acidic extraction and successive chromatography on Sephadex G-50, Toyopearl HW-40 F and reverse-phase high performance liquid chromatography columns. Analysis showed that peptide consists of thirteen amino acids. Primary structure of hLCP has been deduced by double-coupling Edman degradation combined with enzyme digestion as H-Ser-Pro-Pro-Asp-Gly-Lys-Lys-Glx-Ser-Ala-Asp-Val-Lys-OH. hLCP possessed significant excitatory activity on an electrical stimulation induced contraction. No hLCP could be detected in normal lung tissue. The possibility of using hLCP as a biochemical marker in the clinic for the early detection of lung carcinoma is being investigated. 相似文献