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991.
陈国平 《湖北民族学院学报(自然科学版)》1998,16(3):15-17,21
利用凝聚函数讨论了非线性极大极小问题的同伦方法,给出了同伦方法的收敛性。 相似文献
992.
弱激光照射改善红细胞聚集能力的分形研究 总被引:3,自引:0,他引:3
在弱激光血管内照射疗法(ILLLIT)前后血液流变学指标有显著下降的临床实验结果基础上,采用酚分形动力理论,研究了弱激光血管内照射疗法激活血纤溶系统的分形机理。理论分析结果表明,ILLLIT提高了纤维蛋白溶酶原激活素的活性,有利于细细胞聚集指数的下降。 相似文献
993.
通过分析规则熔体的热力学模型,计算了典型金属玻璃的熔体混合焓ΔHmix和混合熵ΔSmix.结合临界冷却速率,归纳出典型金属玻璃形成液体的热力学特性,并提出基于原子尺寸、元素组成以及元素之间混合焓等参数的形成大块金属玻璃的成分判定方法.结果表明,当ΔHmix<-15 kJ·mol-1且ΔSmix>0.6 J·K-1mol-1时,合金易于形成大块金属玻璃.金属玻璃的临界冷却速率Rc具有明显的尺寸效应,其值与熔体的ΔSmix值呈指数关系,可以用Rc=42.24×104exp(-13.91ΔSmix)+19.66粗略判断.运用该方法成功设计并制备出远离原有Zr基大块金属玻璃形成区域(55at%—65at%Zr)的Zr40Al10Ni15Cu35和四元Fe-B基Fe53Co5Nd12B30大块金属玻璃.
关键词:
混合焓
混合熵
大块金属玻璃
玻璃形成能力 相似文献
994.
R. Cuervo‐Rodríguez R. París‐Escribano M. C. Fernndez‐Monreal E. L. Madruga M. Fernndez‐García 《Journal of polymer science. Part A, Polymer chemistry》2005,43(18):4187-4195
Ethyl α‐hydroxymethylacrylate was homopolymerized and copolymerized with methyl methacrylate in chlorobenzene and 1,4‐dioxane solutions at 50 °C with 1.5 × 10?2 mol/L 2,2′‐azobisisobutyronitrile as an initiator and a global monomer concentration of 3.0 mol/L. The experiments showed differences in the calculated values of the monomer reactivity ratios in both solvents. The kinetic behavior was analyzed in terms of the implicit penultimate effect and the radical reactivity ratios. All the parameters were examined with respect to the aggregation ability of the ethyl α‐hydroxymethylacrylate monomer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4187–4195, 2005 相似文献
995.
R. Nagarajan 《Colloids and surfaces. B, Biointerfaces》1999,16(1-4):55-72
Pluronic® block copolymers are commercially available symmetric triblock copolymers with poly(ethylene oxide), PEO, as the hydrophilic end blocks and poly(propylene oxide), PPO, as the hydrophobic middle block. In this paper, the solubilization of hydrocarbons by aggregates of Pluronic® block copolymers in water is examined in the framework of a simple molecular theory of solubilization. The aggregates have an inner core region made up of PPO and the solubilizate and an outer corona region made up of PEO and water. Expressions for the standard state free energy change associated with solubilization of hydrocarbons by aggregates having spherical, cylindrical, and lamellar shapes are presented. These free energy contributions account for the mixing of the core block with the solubilizate, the consequent changes in the state of deformation of the core block, the changes in the state of dilution and deformation of the corona block, the formation of the core-solvent interface, and the backfolding of the triblock copolymer which ensures that the two end blocks are in contact with the solvent. Utilizing these free energy expressions, we predict the core size, the corona thickness, and the aggregation number of the micelle and also the volume fraction of the hydrocarbon solubilized in the core, for seven aromatic and aliphatic hydrocarbon solubilizates incorporated within numerous Pluronic® compounds. The calculated results show that a growth in aggregate size occurs both because of the incorporation of the hydrocarbon and also the increase in the intrinsic number of block copolymer molecules per aggregate. More interestingly, solubilization is shown to induce a transition in aggregate shapes from spheres to cylinders and then to lamellae. The shape transition is found to be critically controlled by the free energy of mixing of the solubilizate with the core forming PPO block. 相似文献
996.
Warm equal channel angular extrusion (ECAE) in 90° tooling is used to consolidate Vitreloy 106a plus tungsten powders. A fully dense amorphous matrix composite showing good infiltration of the amorphous phase in between crystalline particles and uniform consolidation is achieved after one ECAE extrusion in the supercooled liquid temperature region of the amorphous phase. The results demonstrate that ECAE appears to be a viable processing method for producing bulk metallic glass matrix-crystalline particle composites. 相似文献
997.
998.
在轿车的整个开发过程中,零部件、总成和整车产品都必须根据试验结果验证和优化,在轿车开发的过程中测试技术是连接设计师思维空间和现实空间的纽带,现代光学测试技术以数字图象数据处理技术为基础,融汇贯通高速宽带数字采样、数据库和数据自动分析以及计算机智能工程及专家系统等最新技术,巧妙应用于轿车开发过程,在满足计算机虚拟开发工程对测试技术新要求的同时,还可以优化轿车开发程序,提高开发质量,本文以作者多年来在德国轿车开发部门主持的现代测试技术项目的实例介绍采用光测技术解决开发程序中的问题的构想,方法和手段。 相似文献
999.
ON THE RUIN FUNCTIONS FOR A CORRELATED AGGREGATE CLAIMS MODEL WITH POISSON AND ERLANG RISK PROCESSES 总被引:1,自引:0,他引:1
This article considers a risk model as in Yuen et al. (2002). Under this model the two claim number processes are correlated. Claim occurrence of both classes relate to Poisson and Erlang processes. The formulae is derived for the distribution of the surplus immediately before ruin, for the distribution of the surplus immediately after ruin and the joint distribution of the surplus immediately before and after ruin. The asymptotic property of these ruin functions is also investigated. 相似文献
1000.
A
method for describing the lengths of induction periods at linear-heating measurements,
is employed for the study of induction periods in the crystallisation of metallic
glasses. For Fe75Si15B10
glass, close values of the related kinetic parameters were obtained from isothermal
and nonisothermal measurements. On the basis of the results obtained, the
absence of induction period in the first crystallisation step of Al90Fe7Nb3
glass in the isothermal DSC measurement has been elucidated. 相似文献