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131.
本文通过对砖砌烟囱爆破拆除的实例分析得到,在砖砌烟囱的爆破拆除倾倒过程中,其倾倒支点是不断移动的,随着烟囱主体的不断下沉,相对于未垮部分的烟囱主体来说,该支点沿烟囱筒体不断向上移动。这表明,不能简单地按刚体模型描述砖砌烟囱的倾倒运动。 相似文献
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通过对三种不同径厚比圆柱壳进行的流固冲击实验,分析了它们在流固冲击载荷下的动力响应特点,并与相应的高速撞击与静力屈曲实验作了简单的比较,分析了它们之间的异同点。同时文中对极值冲击倒塌特性进行了详细分析 相似文献
134.
Anh T. Vu Xinying Wang S. Ranil Wickramasinghe Bing Yu Hua Yuan Hailin Cong Yongli Luo Jianguo Tang 《Journal of separation science》2015,38(16):2819-2825
Hydrophobic interaction membrane chromatography has gained interest due to its excellent performance in the purification of humanized monoclonal antibodies. The membrane material used in hydrophobic interaction membrane chromatography has typically been commercially available polyvinylidene fluoride. In this contribution, newly developed inverse colloidal crystal membranes that have uniform pores, high porosity and, therefore, high surface area for protein binding are used as hydrophobic interaction membrane chromatography membranes for humanized monoclonal antibody immunoglobulin G purification. The capacity of the inverse colloidal crystal membranes developed here is up to ten times greater than commercially available polyvinylidene fluoride membranes with a similar pore size. This work highlights the importance of developing uniform pore size high porosity membranes in order to maximize the capacity of hydrophobic interaction membrane chromatography. 相似文献
135.
在高温高压(1 000 ℃、12 MPa)固定床反应器上对内蒙古褐煤半焦的加氢甲烷化反应特性进行了研究,采用氮吸附和扫描电镜(SEM)对甲烷化残渣比表面积、孔结构和表面形态进行了表征。结果表明,半焦加氢甲烷化可分为加氢热解、快速加氢和慢速加氢等三个反应阶段,每阶段分别发生含氧官能团和烷基侧链加氢反应、芳环结构加氢反应以及贫氢骨架碳结构加氢反应。半焦加氢甲烷化最优反应温度为800 ℃,反应压力为3.0~4.0 MPa;提高升温速率可以缩短前段(碳转化率低于46%)反应过程时间,对后段(碳转化率高于46%)反应过程影响较小。半焦甲烷化残渣的吸附-脱附等温线呈反S型,滞后环呈H3回线形状;在甲烷化反应过程中,半焦平均孔径先减小后增大,总孔容积和介孔容积逐渐增大,微孔容积和比表面积先增大后减小。 相似文献
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Application of a multivariate approach for analyte focusing by micelle collapse‐micellar electrokinetic chromatography for analyzing sunscreen agents in cosmetics 下载免费PDF全文
Yi‐Hui Lin Chi‐Yu Lu Shiuh‐Jen Jiang Wen‐Yao Hsiao Hui‐Ling Cheng Yen‐Ling Chen 《Electrophoresis》2015,36(19):2396-2403
The operating parameters that affect the performance of the online preconcentration technique “analyte focusing by micelle collapse‐MEKC (AFMC‐MEKC)” were examined using a multivariate approach involving experimental design to determine the sunscreen agents in cosmetics. Compared to the single‐variable approach, the advantage of the multivariate approach was that many factors could be investigated simultaneously to obtain the best separation condition. A fractional factorial design was used to identify the fewest significant factors in the central composite design (cCD). The cCD was adopted for evaluating the location of the minimum or maximum response in this study. The influences of the experimental variables on the response were investigated by applying a chromatographic exponential function. The optimized condition and the relationship between the experimental variables were acquired using the JMP software. The ANOVA analysis indicated that the Tris pH value, SDS concentration, and ethanol percentage influenced the separation quality and significantly contributed to the model. The optimized condition of the running buffer was 10 mM Tris buffer (pH 9.5) containing 60 mM SDS, 7 mM γ‐CD, and 20% v/v ethanol. The sample was prepared in 100 mM Tris buffer (pH 9.0) containing 7.5 mM SDS and 20% v/v ethanol. The SDS concentration in the sample matrix was slightly greater than the CMC value that makes the micelle be easily collapsed and the analytes be accumulated in the capillary. In addition, sunscreen agents in cosmetics after 1000‐fold dilution were successfully determined by AFMC‐MEKC. 相似文献
138.
Fredrik Elwinger Sergey V. Dvinskikh István Furó 《Magnetic resonance in chemistry : MRC》2015,53(8):572-577
A method for measuring the ligand concentration in heterogeneous materials like chromatography media is described. In this method, 13C single pulse excitation magic angle spinning NMR experiment with broadband 1H decoupling is used to determine the peak integrals for a butyl ligand in the spectrum of a dried chromatography medium. Within a carefully controlled protocol, those integrals compared with that of the internal reference compound dimethyl sulfone provide the required volume concentration with an accuracy of ca 2%. The effects of temperature, degree of hydration, and other experimental parameters are discussed. Copyright © 2015 The Authors. Magnetic Resonance in Chemistry published by John Wiley & Sons Ltd. 相似文献
139.
The aim of this paper is to analyze the statistical properties of solute concentration in natural aquifers as sampled in observation wells, having a small diameter in comparison with the characteristic size of the heterogeneity in hydraulic properties. The analysis, in Langragian framework, takes advantage of the reverse formulation, where, instead of considering the destination of the injected particles, the origin of the particle being sampled is sought. In the case of small values of the log-conductivity variance Y2, it allows the derivation of an analytical expression for concentration mean, variance and pdf, while for aquifer characterized by high value in Y2, a numerical analysis based on a Monte Carlo approach using a reverse scheme is developed and applied for values of Y2 up to 2. In this case, the use of a Beta function to fit the concentration pdf proves valid for practical applications. The comparison between the numerical and the analytical results defines the range of validity of the analytical ones. The relative role of large-scale dispersion processes and pore-scale effects is analyzed in terms of global variance in order to point out limits and accuracy of the Eulerian scheme in comparison with the Lagrangian one. 相似文献
140.
Fengqi You Sheng Fu Yangxin Yu Guanghua Gao 《中国颗粒学报》2005,3(5):265-270
A density functional theory is applied to calculating the local density profiles of colloids confined in a slit-like pore as well as the radial distribution functions of bulk colloids. The interaction between the colloidal particles is described using a hard-core Yukawa model. The excess Helmholtz energy functional is a combination of the modified fundamental measure theory of Yu and Wu (2002) for the hard-core contribution and a corrected mean-field theory for the attractive contribution. Comparison with the results from the Monte Carlo simulations shows that the corrected theory improves the density profiles of colloids in the vicinity of contact over the original mean-field theory. Both the present corrected theory and simulations suggest that there are depletion and desorption for the colloid with strong attraction between particles at low temperature. 相似文献