全文获取类型
收费全文 | 402篇 |
免费 | 5篇 |
国内免费 | 12篇 |
专业分类
化学 | 130篇 |
晶体学 | 2篇 |
力学 | 157篇 |
综合类 | 3篇 |
数学 | 16篇 |
物理学 | 111篇 |
出版年
2024年 | 1篇 |
2023年 | 19篇 |
2022年 | 6篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 5篇 |
2017年 | 10篇 |
2016年 | 11篇 |
2015年 | 15篇 |
2014年 | 28篇 |
2013年 | 17篇 |
2012年 | 12篇 |
2011年 | 27篇 |
2010年 | 18篇 |
2009年 | 25篇 |
2008年 | 24篇 |
2007年 | 32篇 |
2006年 | 19篇 |
2005年 | 19篇 |
2004年 | 18篇 |
2003年 | 9篇 |
2002年 | 10篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 6篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 10篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有419条查询结果,搜索用时 15 毫秒
91.
100mg已研磨的食品塑料包装材料,用硝酸4mL和硫酸3mL混合酸消解,采用电感耦合等离子体原子发射光谱法测定所得试样溶液中二氧化钛的含量。选择336.122nm波长为钛的分析线,钛的质量浓度在25 mg·L~(-1)以内与其信号值呈线性关系,方法的检出限(3S/N)为4.0mg·kg~(-1)。方法的加标回收率在93.6%~101.2%之间,相对标准偏差(n=8)小于1%。 相似文献
92.
Junewen Chen Hon-Fai Yau Hai-Pei Liu Tzu-Chiang Chen Chiao-Chia Cheng Fa-Min Liu 《Optics & Laser Technology》2000,32(4)
Four kinds of currently available Nd:hosted laser passive Q-switch and mode-locking modulators: plastic dye sheet, LiF:F2− color center crystal, Cr+4 :YAG crystal and RG1000 colored glass filter were investigated in detail and summarized for comparison for the first time. The LiF:F2− crystal with outstanding annealability, long lifetime, low cost and operability at high repetition rates is highly recommended. 相似文献
93.
Thickness measurement is important in various engineering fields. The several methods have been used to measure the thickness. This work explains a novel method for measuring the thickness of translucent plastic materials using scanner. The plastic samples were scanned against a white and a black background and the RGB parameters of obtained images were used to measure the opacity. Then, the thickness was calculated using relationship between thickness and opacity of samples. The best thickness prediction was obtained using a 3rd polynomial regression with the XYZ parameter. 相似文献
94.
Serge Galam 《Phase Transitions》2013,86(1-4):97-101
A simple Ising-like model is presented to describe the phase diagram of plastic crystals. In addition to a bilinear coupling between translations and rotations a reorientation-translation coupling is introduced via random fields which couple solely to rotational degrees of freedom. The physical basis of the reorientation-translation coupling is discussed using the rotational state hypothesis. The present approach is found to be consistent with some recent neutron experiments. 相似文献
95.
Complexity of plastic response is caused by the fact that plastically deformed solids are composites with a changing structure. At the mesoscale (m) a pattern of high and low dislocation density regions is spontaneously formed. The evolution of the composite structures is treated as a consequence of the structuralization process governed by four types of mechanisms: (i) the overproduction of dislocation, (ii) the screening of their elastic fields, (iii) the formation of dipolar dislocation patterns, (iv) the instability transition leading to the formation of subgrain boundaries, dislocation grids, microshear bands, or persistent slip bands. The proposed theoretical model consists of the balance law for the dislocation density of stored dislocations, the relations which determine the average shape of glide dislocations, and the continuum mechanics equations for stress and strain. To demonstrate the capacity of the model some available solutions simulating the mesoscale structure evolution are briefly reviewed.
Sommario La complessità della risposta plastica è dovuta al fatto che i solidi soggetti a deformazioni plastiche sono corpi compositi di struttura variabile. A mesoscala (m) si forma spontaneamente un insieme di regioni di alta e bassa densità di dislocazioni. Si tratta il comportamento delle strutture composite come conseguenza di un processo di strutturalizzazione governato da quattro tipi di meccanismi: (1) sovrapproduzione di dislocazioni; (2) la schermatura del loro campo elastico;(3) la formazione di tipi di dislocazioni dipolari;(4) transizione di instabilità. Il modello teorico proposto è composto dalle equazioni di bilancio per la densità di dislocazione delle dislocazioni immagazzinate, dalle relazioni che determinano l'andamento medio delle dislocazioni di scorrimento e dalle equazioni della meccanica dei continui per sforzi e deformazioni. Per controllare la validità del modello, si riesaminano brevemente alcune soluzioni conosciute che simulano l'evoluzione della struttura a mesoscala.相似文献
96.
聚乙烯塑料包装材料中4种抗氧化剂向脂肪食品模拟物迁移的研究 总被引:4,自引:0,他引:4
本文基于超高效液相色谱建立了一种脂肪食品模拟物异辛烷中抗氧化剂叔丁基对羟基茴香醚(BHA)、2,6-二叔丁基对甲酚(BHT)、四[甲基-β-(3,5-二叔丁基-4-羟基苯基)丙酸酯]季戊四醇酯(Irganox1010)以及β-(4-羟基-3,5-二叔丁基苯基)丙酸正十八酯(Irganox1076)的提取检测方法,加标回收率在78.0%~108.7%之间,相对标准偏差(RSD)在4.0%~13.7%之间。研究了聚乙烯(PE)膜中抗氧化剂向异辛烷的迁移,讨论了温度及时间对迁移的影响,并根据迁移数据进行了初步的数学模型的建立,对实验值与数值模拟结果计算值作了对比分析。 相似文献
97.
In this paper, a macroscopic anisotropic strain rate potential, which can describe both the anisotropy and tension-compression asymmetry of the plastic response of textured metals is derived. This strain rate potential is the exact work-conjugate of the anisotropic stress potential CPB06 of Cazacu et al. (2006). Application of the developed strain rate potential to HCP high-purity alpha-titanium is presented. 相似文献
98.
Ujwala Hujuri 《Polymer Degradation and Stability》2008,93(10):1832-1837
Modeling pyrolysis behavior of waste plastic mixtures is of importance for design and operation of reactors which convert these waste plastics into valuable chemicals. However, because of limited understanding of their degradation behavior even for single component plastic wastes, modeling degradation kinetics of plastic mixtures is a challenging task.In this work, we report modeling of binary and ternary mixture degradation kinetics of polyethylene terephthalate (PET), low density polyethylene (LDPE) and polypropylene (PP). A simple mixing rule approach was used with one cross-kinetic degradation parameter per each binary. Ternary kinetics were completely predictive and showed good agreement with the experimental data. 相似文献
99.
Christian Mans Stephanie Hanning Christoph Simons Anne Wegner Anton Janβen Martin Kreyenschmidt 《Spectrochimica Acta Part B: Atomic Spectroscopy》2007
For the adoption of the EU directive “Restriction on use of certain Hazardous Substances” and “Waste Electrical and Electronic Equipment” using X-ray fluorescence analysis suitable standard materials are required. 相似文献
100.