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81.
The present study optimised the ultrasound-assisted extraction (UAE) of bioactive compounds from Amaranthus hypochondriacus var. Nutrisol. Influence of temperature (25.86–54.14 °C) and ultrasonic power densities (UPD) (76.01–273.99 mW/mL) on total betalains (BT), betacyanins (BC), betaxanthins (BX), total polyphenols (TP), antioxidant activity (AA), colour parameters (L*, a*, and b*), amaranthine (A), and isoamaranthine (IA) were evaluated using response surface methodology. Moreover, betalain extraction kinetics and mass transfer coefficients (KLa) were determined for each experimental condition. BT, BC, BX, TP, AA, b*, KLa, and A were significantly affected (p < 0.05) by temperature extraction and UPD, whereas L*, a*, and IA were only affected (p < 0.05) by temperature. All response models were significantly validated with regression coefficients (R2) ranging from 87.46 to 99.29%. BT, A, IA, and KLa in UAE were 1.38, 1.65, 1.50, and 29.93 times higher than determined using conventional extraction, respectively. Optimal UAE conditions were obtained at 41.80 °C and 188.84 mW/mL using the desired function methodology. Under these conditions, the experimental values for BC, BX, BT, TP, AA, L*, a*, b*, KLa, A, and IA were closely related to the predicted values, indicating the suitability of the developed quadratic models. This study proposes a simple and efficient UAE method to obtain betalains and polyphenols with high antioxidant activity, which can be used in several applications within the food industry.  相似文献   
82.
In order to investigate the effects of thermoultrasonic treatment (TUT) on the formation of colloidal micro-nano particles (MNPs) and the quality of halibut bone soup, nutrients, particle characteristics, and flavor characteristics were analyzed. The morphology of MNPs was studied using an optical microscope. Results showed that TUT could increase the nutrient content (total sugars, 22.15 mg/100 mL; water soluble proteins, 173.24 mg/mL; fatty acids, 1779.7 mg/100 mL; solids, 3.16 g/100 mL), reduce the particle size (605.92 nm) and interfacial tension. Meanwhile, TUT make the halibut bone soup has better emulsifying characteristics and stability. The contents of flavor substances, such as esters, 5′-nucleotides, organic acids in the halibut bone soup were more abundant, while the contents of hexanal and 1-octen-3-ol and fishy off-flavor were reduced in TUT group. The overall odor and taste outline were more harmonious. Therefore, TUT can be used in the production of high quality fish bone soup, and TUT could be considered as a good deep processing technology for halibut bone and improve economic efficiency.  相似文献   
83.
Fission properties of the actinide nuclei are deduced from theoretical analysis. We investigate potential energy surfaces and fission barriers and predict the fission fragment mass yields of actinide isotopes. The results are compared with experimental data where available. The calculations were performed in the macroscopic-microscopic approximation with the Lublin-Strasbourg Drop (LSD) for the macroscopic part, and the microscopic energy corrections were evaluated in the Yukawa-folded potential. The Fourier nuclear shape parametrization is used to describe the nuclear shape, including the non-axial degree of freedom. The fission fragment mass yields of the nuclei considered are evaluated within a 3D collective model using the Born-Oppenheimer approximation.  相似文献   
84.
This is the first of two articles(Part I and Part II)that presents the results of the new atomic mass evaluation,Ame2020.It includes complete information on the experimental input data that were used to derive the tables of recommended values which are given in Part II.This article describes the evaluation philosophy and procedures that were implemented in the selection of specific nuclear reaction,decay and mass-spectrometric data which were used in a least-squares fit adjustment in order to determine the recommended mass values and their uncertainties.All input data,including both the accepted and rejected ones,are tabulated and compared with the adjusted values obtained from the least-squares fit analysis.Differences with the previous Ame2016 evaluation are discussed and specific examples are presented for several nuclides that may be of interest to Ame users.  相似文献   
85.
In this paper, we have analyzed the mathematical model of various nonlinear oscillators arising in different fields of engineering. Further, approximate solutions for different variations in oscillators are studied by using feedforward neural networks (NNs) based on the backpropagated Levenberg–Marquardt algorithm (BLMA). A data set for different problem scenarios for the supervised learning of BLMA has been generated by the Runge–Kutta method of order 4 (RK-4) with the “NDSolve” package in Mathematica. The worth of the approximate solution by NN-BLMA is attained by employing the processing of testing, training, and validation of the reference data set. For each model, convergence analysis, error histograms, regression analysis, and curve fitting are considered to study the robustness and accuracy of the design scheme.  相似文献   
86.
F. A. Akin 《Molecular physics》2013,111(24):3556-3566
ABSTRACT

The structures, ionisation energies (IE), and electron affinities (EA) of 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) isomers upon loss and gain of an electron were calculated using density functional theory (DFT) methods. The adiabatic electron affinities (EAad) range from 1 to 2 eV. The vertical detachment energies are between 1.3 and 4.0 eV. The adiabatic ionisation energies (IEad) are in the 9.9–10.2 eV range. The vertical ionisation energies are in the 10.4–10.9 eV range. It is shown that NO2?/NO2 loss would be common in anions and cations, respectively. Isomerisation and N—N bond dissociation accompany cation and anion formation, respectively. The suggested mass spectral fragmentation products for the cations along the S0 surface are 84, 130, and 176 amu, in agreement with earlier mass spectrometry studies.  相似文献   
87.
It is essential to establish whether and how environmental factors affect the reliability of [13C]methacetin breath test (13C-MBT). In 12 healthy volunteers (smokers), a standard 13C-MBT with 75 mg [13C]methacetin was performed twice in random order: on a control day without smoking and on another day with smoking two cigarettes antecedently. A considerable flattening of the curve of the momentary 13C recovery within the expiratory air was observed when the 13C-MBT was performed after smoking. The maximum of the momentary 13C recovery, D max, decreased from 37.20±2.58 to 25.39±2.29% dose/h (p=0.00052). Moreover, the time to reach D max was prolonged after cigarette smoking (26.5±3.1 vs. 16.5±1.9 min, p=0.0199). The curve of the cumulative 13C recovery on the cigarette smoking day appeared to be shifted downwards, and statistically significant differences relative to the control situation were found between the 24th and 75th minute following [13C]methacetin administration. Smoking cigarettes immediately prior to the 13C-MBT diminishes the ability of the liver to handle methacetin, and hence a possibility of such an interaction should be excluded in order to interpret the results of the test correctly.  相似文献   
88.
The concentrations of 14 elements in Lycium barbarum L. leaves collected from the Qaidam basin (China) were determined by inductively coupled plasma mass spectrometry after microwave assisted digestion. This work presents two goals: (1) to determine 14 elements in L. barbarum leaves; (2) to examine the relationship between elements using correlation analysis, principal component analysis, and cluster analysis. The accuracy and precision were verified against a GBW07605 Tea Leaves certified reference material. The results demonstrated that the method was reliable, reproducible, and suitable for determination of the concentrations of trace elements in L. barbarum leaves. Correlation analysis showed that aluminum–copper, arsenic–zinc, manganese–selenium, and chromium–iron have medium correlation coefficients. Principal component loading for L. barbarum leaves extracted seven components explained about 85% of the total variance. Cluster analysis depicts four clusters: (1) arsenic and titanium; (2) calcium, magnesium, manganese, selenium, and zinc; (3) cobalt, iron, and molybdenum; (4) aluminum, copper, and chromium.  相似文献   
89.
ABSTRACT

In this paper, lanthanum was used as a chemical modifier for the direct determination of erbium by high-resolution continuum source electrothermal atomic absorption spectrometry. A two-step experimental design was used for optimization, first a full factorial design was conducted for identification of significant factors, and then a central composite design was carried out for final optimization of the significant factors. The optimum parameters were obtained as follows: atomization temperature of 2500°C, pyrolysis temperature of 1600°C, and pyrolysis time of 10?s in the presence of lanthanum as a chemical modifier. Under optimum conditions, the characteristic mass, limit of detection, and limit of quantification were 29?pg, 0.71, and 2.4?µg?L?1, respectively. The precision of the method, estimated as the relative standard deviation for 10 replicate measurements of 50?µg?L?1 of erbium, was 1.8%. The optimized method was applied to determine erbium content in sediments and rock samples. The determined values of erbium in sediment certified reference materials were in satisfactory agreement with the certified values according to the t-test for a 95% confidence level.  相似文献   
90.
Abstract

A new flow‐injection online reduction electrochemical hydride generation system for the determination of Se(IV) and Se(VI) by atomic fluorescence spectrometry (AFS) was developed. In the system, an electromagnetic induction oven was used as heating resource to reduce Se(VI) to Se(IV) and a homemade tubular electrolytic cell as hydride generator. All analytical procedures were automatically controlled by a computer. The conditions of online reduction, including temperature, HCl concentration, and reduction time, have been studied in detail. The detection limits (3σ) of Se(IV) and Se(VI) in aqueous solution were 0.26 µg L?1 and 0.23 µg L?1, respectively. The precision for 11 replicate measurements of 50 µg L?1 Se(IV) and Se(VI) was 2.2% and 2.5%. This proposed method has been applied to the determination of Se(IV) and Se(VI) in springwater samples.  相似文献   
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