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91.
The precision and computational efficiency of the shift operator finite-difference time-domain (SO-FDTD) method are compared with those of the piecewise linear current density recursive convolution (PLCDRC) method by simulating the electromagnetic wave at different frequency propagation in homogeneous unmagnetized plasma in this paper. The results show that the two methods almost have the same precision, but the CPU time of the SO-FDTD method is less than that of the PLCDRC method, this is because the SO-FDTD method eliminates many convolution operations of the PLCDRC method. 相似文献
92.
Xin Liu Ze-Shu Wang Tong-Yi Zhai Chen Luo Yi-Ping Zhang Yang-Bo Chen Prof. Dr. Chao Deng Prof. Dr. Rai-Shung Liu Prof. Dr. Long-Wu Ye 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(41):18140-18146
Here an efficient copper-catalyzed cascade cyclization of azide-ynamides via α-imino copper carbene intermediates is reported, representing the first generation of α-imino copper carbenes from alkynes. This protocol enables the practical and divergent synthesis of an array of polycyclic N-heterocycles in generally good to excellent yields with broad substrate scope and excellent diastereoselectivities. Moreover, an asymmetric azide–ynamide cyclization has been achieved with high enantioselectivities (up to 98:2 e.r.) by employing BOX-Cu complexes as chiral catalysts. Thus, this protocol constitutes the first example of an asymmetric azide–alkyne cyclization. The proposed mechanistic rationale for this cascade cyclization is further supported by theoretical calculations. 相似文献
93.
《Ultrasonics sonochemistry》2014,21(1):98-103
The ultrasound-assisted synthesis of lutein disuccinate from all-trans lutein (AL) and succinic anhydride (SA) was investigated in this study. Triethylamine was used as the catalyst. Based on the single-factor experiments, a 7-level-3-factor uniform design and response surface analysis were further employed to evaluate the effects of the selected variables including molar ratio of SA/AL, reaction time and ultrasonic power on the yield of lutein disuccinate. The results indicated that the data were adequately fitted into a second-order polynomial model; the molar ratio of SA/AL significantly affected the synthesis of lutein disuccinate, whereas reaction time and ultrasonic power did not. Based on ridge max analysis, the optimum condition for lutein disuccinate synthesis was predicted to be the molar ratio of SA/AL 265.3:1, ultrasonic power 300 W and reaction time 131.6 min with the lutein disuccinate yield of 80.53 ± 0.18%, which give a 43.8% increase compared with the traditional method, and also significantly shorten the reaction time. 相似文献
94.
95.
96.
Hui Min Wu Li Ping Lin Qin Lan Xu Wen Bo Han Song Zhang Ze Wen Liu Ya Ning Mei Zhu Jun Yao Ren Xiang Tan 《Tetrahedron letters》2017,58(7):663-665
Nodupetide (1), a new cyclodepsipeptide unique in its incorporation of a 3-hydroxy-4-methylhexanoic acid (HMHA) derived motif, was discovered from Nodulisporium sp. IFB-A163, a fungus residing in the insect (Riptortus pedestris) gut. The nodupetide structure was elucidated by its MS/MS and 2D NMR spectra, and its absolute configuration by the X-ray crystallography and modified Marfey’s method. Nodupetide is insecticidal against rice brown planthopper (Nilaparvata lugens) with an LD50 value of 70 ng/larva, and inhibitory towards the drug-resistant human pathogenic bacterium Pseudomonas aeruginosa with its MIC value (5.0 μM) comparable to that (3.2 μM) of ciprofloxacin, a prescribed antibacterial agent co-assayed equally. 相似文献
97.
98.
We propose different types of Łojasiewicz inequality at infinity for polynomials in two real variables. The formulas for the
Łojasiewicz exponents are given. 相似文献
99.
Ten methyl 2‐methoxyimino‐2‐{2‐[(substituted benzylidene)aminooxymethyl]phenyl}acetate and 2‐methoxy‐ imino‐2‐{2‐[(substituted benzylidene)aminooxymethyl]phenyl}‐N‐methylacetamide derivatives were synthesized. Structures of the new compounds were characterized by IR, 1H NMR and GC‐MS data. These compounds at 10 µg/mL were tested in vitro against five pathogenic fungi, namely, Sclerotonia, Botrytis cinerea Pers, Gibberella zeae, Rhizoctorua solani and Pyricularia oryzae. Compounds G5 , G6 , G7 and G8 showed potent antifungal activities against Botrytis cinerea Pers, G7 against Gibberella zeae and G7 , G8 against Rhizoctorua solani, respectively. 相似文献
100.
《The Journal of chemical thermodynamics》2002,34(3):303-317
A flow mixing calorimeter, followed by a vibrating tube densimeter, has been used to measure excess molar enthalpies HmEand excess molar volumesVmE of {xCO2 + (1 − x)SF6}. Measurements over a range of mole fraction x have been made at the temperatures T = 302.15 K and T = 305.65 K at the pressures (3.76, 5.20, 6.20, and 7.38) MPa. The lowest pressure 3.76 MPa is close to thecritical pressure of SF6 and the highest pressure 7.38 MPa is close to the critical pressure of CO 2. Measurements atx = 0.5 have been made over the pressure range (2.5 to 10.0) MPa at the temperature 301.95 K. Some of the measurements are very close to the critical locus of the mixture. The measurements are compared with the Patel–Teja equation of state which reproduces the main features of the excess function curves as well as it does for similar measurements on {xCO2 + (1 − x)C2H6} and{xCO2 + (1 − x)C2H4} . The equation was used to calculate residual enthalpies and residual volumes for the pure components and for the mixture, and inspection of the way these combine to give excess enthalpies and volumes assisted the interpretation of the pressure scan measurements. 相似文献