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81.
C Paz-Ramos C A Cerdeiriña J Troncoso L Romaní 《Journal of Thermal Analysis and Calorimetry》2006,83(2):263-268
In the search of a useful
method for determining excess enthalpies as a function of temperature Calvet
calorimetry was employed. To this end, excess molar enthalpies
at 298.15 and 333.15 K and excess molar heat capacities
within 283.15–333.15 K were
determined for the 1-decanol+n-decane system
over the whole composition range. An isothermal flow Calvet-type calorimeter
was used for
measurements, whereas
were determined by means of a Setaram
Micro DSC calorimeter. Excess enthalpies within 283.15–333.15 K were
indirectly obtained through the integration of
(T) data using
at 298.15 K. The results obtained at 333.15 K agreed with those
determined directly, implying the thermodynamic consistency of the measured
data and, therefore, the reliability of the indirect method. 相似文献
82.
采用高效液相色谱法测定丹参超微粉体和常规粉体中丹参酮ⅡA体外溶出量和溶出速率.丹参超微粉体和常规粉体中丹参酮ⅡA体外溶出量无显著性差异,超微粉体的溶出速率较常规粉体明显增加.实验表明超微粉碎可明显提高丹参酮ⅡA溶出速率. 相似文献
83.
Sunit Kumar Sahoo Gyanada Sankar Dash Satyajeet Biswal Prasanta Kumar Biswal 《Journal of Dispersion Science and Technology》2019,40(3):464-475
The current work designed to fabricate and evaluate self-nanoemulsfying oil formulations (SNEOFs) of Efavirenz (Efz) a BCS class II drug with the objective of increasing its solubility as well as in vitro dissolution rate for improvisation of bioavailability. Preliminary screening of drug which includes solubility, emulsifying ability and ternary phase diagrams was carried out to fabricate SNEOFs. Various thermodynamic stability studies were exercised to find out the stable SNEOFs. Robustness to dilution, % transmittance and turbidity, droplet size analysis, TEM study, cloud point measurement, viscosity and refractive index were executed on the stable SNEOFs to characterize the delivery system. FTIR study was adopted for the compatibility of the additives with the drug. In vitro release profiles of SNEOFs compared with Efz, percent dissolution efficiency (DE) and dissolution half-life (t50) were evaluated. A low percent DE (30.12%) and high t50 was obtained for Efz whereas all SNEOFs showed a DE of greater than 78.48% and less than 9?min t50. The optimized SNEOFs (F8) demonstrated a significant (p?<?0.05) increase in bioavailability over Efz. Thus the designed optimized delivery system could be instrumental in increasing aqueous solubility of Efz, improving its release performance and enhancement of oral absorption. 相似文献
84.
This letter reports a simple rule on the sequential bond enthalpies D(B(M)x − M) in clusters B(M)x + 1, where B is a bonding particle (neutrals, cations, anions, complexes, biochemical particles), M is a neutral material molecule (inorganic and organic) or atom (metal, non-metal and rare gas), x describes the cluster size, and x = 0, 1, 2, 3, …, etc. Thousands of experimental results for 60 kinds of materials M and 310 kinds of clusters B(M)x + 1 strongly support the simple rule: the sequential bond enthalpies in clusters regularly drop to an intrinsic value, the vaporization enthalpies of the liquid-phase materials M, i.e., D(B(M)x − M, large x) ~ ΔvapH(M). Using this simple rule, we have discussed the possibility of liquid-phase carbon. 相似文献
85.
A convenient new method for the simultaneous determination of losartan potassium and hydrochlorothiazide, with minimum sample
pretreatment, is described. The procedure, based on the multivariate analysis of spectral data in the 220−274 nm region by
the partial least squares algorithm, is linear in the concentration range 1.06−5.70 mg L−1 for hydrochlorothiazide and 4.0−22.2 mg L−1 for losartan. It is simple, rapid and robust, allowing accurate and precise results, with drug recovery rates of 99.3 and
100.4% and relative standard deviations of 1.7 and 1.0% obtained for hydrochlorothiazide and losartan, respectively. The method
was applied to the simultaneous determination of both analytes in tablets, and it provided good results which were in statistical
agreement with those provided by independent HPLC analyses of the samples. The method has also been successfully applied for
the construction of drug dissolution profiles of a commercial pharmaceutical preparation containing both analytes.
Figure A UV-PLS method for the simultaneous determination of losartan potassium and hydrochlorothiazide in pharmaceutical tablet
formulations has been developed and validated 相似文献
86.
87.
Dimple Sharma Jaibir S. Yadav Satish Kumar K.C. Singh V.K. Sharma 《Thermochimica Acta》2008,475(1-2):8-14
Molar excess volumes, VE, molar excess enthalpies, HE, and speeds of sound, u, of o-toluidine (i) + cyclohexane or n-hexane or n-heptane (j) binary mixtures have been determined over entire range of composition at 308.15 K. Speeds of sound data have been utilized to predict isentropic compressibility changes of mixing, of (i + j) mixtures. The observed VE, HE and data have been analyzed in terms of Graph theory. The analysis of VE data by Graph theory reveals that o-toluidine exists as an associated molecular entity and (i + j) mixtures contain 1:1 molecular complex. It has been observed that VE, HE and values calculated by Graph theory compare well with their corresponding experimental values. The observed data have also been analyzed in term of Flory theory. 相似文献
88.
89.
Steven M. Maley Graham R. Lief Richard M. Buck Orson L. Sydora Qing Yang Steven M. Bischof Daniel H. Ess 《Journal of computational chemistry》2023,44(4):506-515
Quantum-mechanical-based computational design of molecular catalysts requires accurate and fast electronic structure calculations to determine and predict properties of transition-metal complexes. For Zr-based molecular complexes related to polyethylene catalysis, previous evaluation of density functional theory (DFT) and wavefunction methods only examined oxides and halides or select reaction barrier heights. In this work, we evaluate the performance of DFT against experimental redox potentials and bond dissociation enthalpies (BDEs) for zirconocene complexes directly relevant to ethylene polymerization catalysis. We also examined the ability of DFT to compute the fourth atomic ionization potential of zirconium and the effect the basis set selection has on the ionization potential computed with CCSD(T). Generally, the atomic ionization potential and redox potentials are very well reproduced by DFT, but we discovered relatively large deviations of DFT-calculated BDEs compared to experiment. However, evaluation of BDEs with CCSD(T) suggests that experimental values should be revisited, and our CCSD(T) values should be taken as most accurate. 相似文献
90.
Dr. Dao-Sheng Liu Zhaoyu Zhang Dr. Yufei Zhang Dr. Minghui Ye Song Huang Shunzhang You Zijian Du Jiangfeng He Dr. Zhipeng Wen Dr. Yongchao Tang Prof. Xiaoqing Liu Prof. Cheng Chao Li 《Angewandte Chemie (International ed. in English)》2023,62(5):e202215385
The anode-cathode interplay is an important but rarely considered factor that initiates the degradation of aqueous zinc ion batteries (AZIBs). Herein, to address the limited cyclability issue of V-based AZIBs, Al2(SO4)3 is proposed as decent electrolyte additive to manipulate OH−-mediated cross-communication between Zn anode and NaV3O8 ⋅ 1.5H2O (NVO) cathode. The hydrolysis of Al3+ creates a pH≈0.9 strong acidic environment, which unexpectedly prolongs the anode lifespan from 200 to 1000 h. Such impressive improvement is assigned to the alleviation of interfacial OH− accumulation by Al3+ adsorption and solid electrolyte interphase formation. Accordingly, the strongly acidified electrolyte, associated with the sedated crossover of anodic OH− toward NVO, remarkably mitigate its undesired dissolution and phase transition. The interrupted OH−-mediated communication between the two electrodes endows Zn||NVO batteries with superb cycling stability, at both low and high scan rates. 相似文献