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91.
In this paper, the spectral behavior of protein and Poniacyl Carmine 2B (PC 2B) has been studied by spectrophotometric method. The conditional constants, apparent combination constant K and maximum binding number n, were used to express the combination ability of the reactions between PC 2B and protein under a set of given conditions. The Sandell index s was used to express the sensitivity of the determination of protein. The factors, acidity, PC 2B concentration and the ionic strength, were discussed by the change of apparent combination constant and maximum binding number. It was found that acidity of the solution, PC 2B concentration and ionic strength had a significant effect on the sensitivity of the assay of protein. Under the optimal conditions, the apparent combination constant K and the maximum binding number n were 2.36 × 106 L mol?1 and 95, respectively. With further investigation, it was found that the Scatchard model was suitable in treating the data obtained in the experiments. In the buffer medium of HCl‐KCl at 1.87, the addition of protein made the maximum absorption of the system move from 527 nm to 513 nm. Its apparent molar absorptivity is 4.46 × 105 Lmol?1 cm?1 at 513 nm. Beer's law is obeyed in the range of 0 ? 55 μg mL?1. The system developed in this paper has been used for the determination of protein in milk powder successfully. 相似文献
92.
重整汽油近红外光谱的稳健偏最小二乘解析 总被引:1,自引:0,他引:1
近红外光谱(NIR)光谱复杂,组分间光谱重叠严重,目前,多元线性回归(MultipleLinearRe gression,MLR)和偏最小二乘法(PartialLeast squares,PLS)是近红外光谱分析中使用最多和效果较好的方法[1]。稳健偏最小二乘(RobustPartialLeast Squares,RPLS)是由稳健统计学构造的具有稳健性能的多元校正方法。当化学测量中引入随机异常点或误差的内在分布偏离正态分布时,它仍能给予接近最优性能的校正,确保分析结果的准确性,是消除奇异点的非常有效的方法[2-4],… 相似文献
93.
We developed a new method to measure the average aggregation number of large rod-like micelles using static fluorescence self-quenching of a solubilized fluorophore. The method is based on the increase of self-quenching of micelle-solubilized pyrene through excimer formation. We consider the effect of random distribution of pyrene in micelles and the micellar size distribution. The measured average aggregation <n> M is based on a new M-weighted raging similar to our exponential-weighted averaging in the transient decay method. We apply this method to study the effect of a large concentration of salt on the average aggregation behavior of sodium dodecyl sulfate (SDS) and cetyle tetraammonium bromide (CTAB). The sizes increase with increasing ionic concentrations. For SDS, we used the thermodynamic model developed by Missel et al. to calculate < n > M which we compare with experimental results. 相似文献
94.
The apparent molar volumes, V,2, of glycine, L-alanine, DL--amino-n-butyric acid, L-valine, and L-leucine have been determined in aqueous 0.25, 0.75, 1.0, and 1.5 mol-dm–3 tetraethylammonium bromide (TEAB) solutions by density measurements at 298.15 K. These data have been used to calculate the infinite dilution apparent molar volumes, V2,m, for the amino acids in aqueous tetraethylammonium bromide and the standard partial molar volumes of transfer (tr V2,m) of the amino acids from water to the aqueous salt solutions. The linear correlation of V2,m for a homologous series of amino acids has been utilized to calculate the contribution of the charged end groups (NH3+, COO–), CH2 group, and other alkyl chains of the amino acids to V2,m. The results of the standard partial molar volumes of transfer from water to aqueous tetraethylammonium bromide have been interpreted in terms of ion–ion, ion–polar, and hydrophobic–hydrophobic group interactions. The volume of transfer data suggest that ion–ion or ion–hydrophilic interactions are predominant in the case of glycine and alanine, and hydrophobic–hydrophobic group interactions are predominant in the case of DL--amino butyric acid, L-valine, and L-leucine. 相似文献
95.
96.
应用分子动力学模拟了25 ℃和50 ℃时新型室温熔盐二(三氟甲基磺酸酰)亚胺锂[LiN(SO2CF3)2, LiTFSI]与尿素(摩尔比为1:3.6)体系的结构与动力学性质. 在两个温度下体系的微观结构基本相同, Li+的配位数约为5, 且都是与溶剂和阴离子中的氧原子发生配位. 对TFSI-的研究表明, 每个TFSI-只提供四个氧中的一个与Li+配位; 而且在Li+的配位层中, TFSI-具有顺、反和gauche 等不同的构象, 并且不同构象出现的几率会随着温度的改变而改变. 相似文献
97.
Different structures have been found for poly(α-tetrathiophene) [poly(α-4TF)] electrosynthesized on Pt by anodic oxidation of 1.0 mM monomer solutions in media such as 45:35:20 (v/v/v) acetonitrile/THF/DMF, 45:35:20 (v/v/v) acetonitrile/ethanol/DMF and 72:28 (v/v) acetonitrile/DMF containing 0.1 M LiClO4; as well as 72:28 (v/v) acetonitrile/DMF with 0.1 M NaClO3, under dynamic and static conditions at 25 °C. In all cases the polymer was generated by chronoamperometry at 1.000 V vs. Ag∣AgCl, corresponding to the first oxidation peak detected by cyclic voltammetry. Uniform, adherent, insoluble and black polymer films were obtained under these conditions. The resulting structures have been elucidated by combining the information of their IR spectrum, nox-value and doping level of the counterion. The degree of crosslinking of every polymer has been quantified and related to the molecular flow of monomer on the Pt electrode. A monomer concentration flow between 4 × 10−6 and 5 × 10−6 mmol cm−2 s−1 was determined as the limiting value below which the polymer grows with crosslinking. This value corresponds to the electropolymerization rate of α-4TF by Pt area unit at 25 °C. 相似文献
98.
Tomislav Došlić 《Journal of mathematical chemistry》2007,41(3):217-229
A global forcing set in a simple connected graph G with a perfect matching is any subset S of E(G) such that the restriction of the characteristic function of perfect matchings of G on S is an injection. The number of edges in a global forcing set of the smallest cardinality is called the global forcing number
of G. In this paper we prove several results concerning global forcing sets and numbers of benzenoid graphs. In particular, we
prove that all catacondensed benzenoids and catafused coronoids with n hexagons have the global forcing number equal to n, and that for pericondensed benzenoids the global forcing number is always strictly smaller than the number of hexagons. 相似文献
99.
Summary Complexation equilibria of the Tl(I) ion with 18-crown-6 and dibenzo-18-crown-6 were studied polarographically in 10 nonaqueous solvents. The stability of the complexes is strongly influenced by the nature of solvents and varies with their Lewis basicities. It has been found that the logK
s value (K
s is the stability constant of the complex) can be well described by empirical relation logK
s=a DN+b, whereDN stands for the Gutmann donor number anda andb mark the regression coefficient. Addition of the second explanatory parameter, the acceptor number, is not statistically significant. This result is in agreement with the predominant role of Tl(I) ion solvation.
Elektrochemische Untersuchungen von Tl(I)-Kronenetherkomplexen in nichtwäßrigen Medien
Zusammenfassung Es wurden die Komplexierungsgleichgewichte des Tl(I)-Ions mit 18-Krone-6 und Dibenzo-18-krone-6 polarographisch in 10 nichtwäßrigen Lösungsmitteln untersucht. Die Stabilität der Komplexe wird sehr stark vom Solvens beeinflußt, wobei eine starke Abhängigkeit von der Lewis-Basizität beobachtet wird. Es wurde festgestellt, daß die logK s-Werte (K s ist die Komplexstabilitätskonstante) gut mit der empirischen Beziehung logK s=a DN+b beschrieben werden können, wobeiDN die Gutmann'sche Donorzahl unda undb die Regressionskonstanten bedeuten. Hinzunahme der Akzeptorzahl als zweiten Parameter bleibt statistisch insignifikant. Dieses Ergebnis stimmt mit dem dominierenden Einfluß der Tl(I)-Ionensolvatation überein.相似文献
100.
The concentration fields, Nusselt number distributions along the electrode, and ratios of concentrations of electrochemically active components at the entrance into and exit out of an electrochemical cell are determined by numerical integration of the convective-diffusion equation for a broad range of rate constants of electrode reactions, Peclet numbers, and geometrical parameters of channels. Three regions of parameter values are revealed. At low reaction rates (K
l
< 0.5), mass transfer is completely determined by electrode kinetics; at high rates (K
l
> 20), it is completely determined by the diffusion in the gas phase; and in the intermediate region of values of K
l
it is necessary to allow for both the diffusion processes and the electrode reactions.Translated from Elektrokhimiya, Vol. 41, No. 3, 2005, pp. 317–324.Original Russian Text Copyright © 2005 by Ezin, Somov. 相似文献