全文获取类型
收费全文 | 325篇 |
免费 | 10篇 |
国内免费 | 27篇 |
专业分类
化学 | 145篇 |
力学 | 9篇 |
综合类 | 7篇 |
数学 | 57篇 |
物理学 | 144篇 |
出版年
2023年 | 1篇 |
2013年 | 1篇 |
2012年 | 3篇 |
2011年 | 27篇 |
2010年 | 17篇 |
2009年 | 28篇 |
2007年 | 4篇 |
2006年 | 8篇 |
2005年 | 23篇 |
2004年 | 57篇 |
2003年 | 54篇 |
2002年 | 33篇 |
2001年 | 36篇 |
2000年 | 10篇 |
1999年 | 6篇 |
1998年 | 15篇 |
1997年 | 2篇 |
1996年 | 6篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 1篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1986年 | 2篇 |
排序方式: 共有362条查询结果,搜索用时 15 毫秒
1.
2.
Jiang Mingxiao Zhu Weiqiu Zhejiang University Hangzhou P. R. China 《Acta Mechanica Solida Sinica》1996,9(2):169-178
Two stochastic models of fatigue crack growth under constant amplitude cyclic loadingare proposed and studied by using the stochastic averaging method and total probability theorem to ac-count for high frequency component and low frequency component, respectively, of the irregular na-ture of fatigue crack growth observed in Virkler's experiment. Particular attention is paid to the predic-tion performance of the models under a change in the initial crack length. It is shown that the modelsproposed in the present paper yields better agreement with experimental data than other models avail-able in literature. 相似文献
3.
4.
We propose a new analytical edge spread function (ESF) fitting model to measure the modulation transfer function (MTF).The ESF data obtained from a slanted-edge image are fitted to our model through the non-linear least squares (NLLSQ) method.The differentiation of the ESF yields the line spread function (LSF),the Fourier transform of which gives the profile of two-dimensional MTF.Compared with the previous methods,the MTF estimate determined by our method conforms more closely to the reference.A practical application of our MTF measurement in degraded image restoration also validates the accuracy of our model. 相似文献
5.
CUI YuanQing & YANG Wei School of Aerospace Engineering Applied Mechanics Tongji University Shanghai China University Office Zhejiang University Hangzhou 《中国科学:物理学 力学 天文学(英文版)》2011,(5)
Experimental results indicate three regimes for cracking in a ferroelectric double cantilever beam (DCB) under combined electromechanical loading. In the loading, the maximum amplitude of the applied electric field reaches almost twice the coercive field of ferroelectrics. Thus, the model of small scale domain switching is not applicable any more, which is dictated only by the singular term of the crack tip field. In the DCB test, a large or global scale domain switching takes place instead, which is driven... 相似文献
6.
Preparation of an amphiphilic graft copolymer having poly(phthalazinone ether sulfone ketone)(PPESK) as main chains was carried out by atom transfer radical polymerization(ATRP).The precursor,chloromethylated PPESK (CMPPESK),was prepared by using chioromethylether as chloromethylation agent.Then,poly(ethylene glycol) methyl ether methacrylate(PEGMA) was used as monomer to synthesize PPESK-g-P(PEGMA) by ATRP method under the catalysis of a cuprous chloride/2,2'-bipyridyl system.PPESK/PPESK-g-P(PEGMA) blen... 相似文献
7.
Poly(styrene-co-glycidyl methacrylate) latex microspheres with uniform size and high-density epoxy groups on the surface were prepared by soap-free emulsion polymerization with batch wise operation mode in the presence of 2.2′- azobis(2-methylpropionamidine) dihydrochloride as an initiator.The kinetics of soap-free emulsion polymerization and the effects of polymerization factors were examined.In addition,the optimum polymerization conditions of poly(styrene-co- glycidyl methacrylate) latex microspheres ... 相似文献
8.
A novel method for determination of formaldehyde sulfoxylate,sulfite,thiocyanate,and thiosulfate in foodstuffs by ion chromatography separation with postcolumn derivation and UV detection has been developed.All species are separated at Dionex IonPac AG22A and AS22A with mobile phase of a mixture of 4.5 mmol/L sodium carbonate and 0.8 mmol/L sodium bicarbonate at a flow-rate of 1.0mL/min.The postcolumn derivation solution was 0.24%iodine in 0.2%phosphate acid and the detection wavelength was set at 288 nm... 相似文献
9.
Two new C-glucofuranosyl isoflavones of impurities in puerarin injection were isolated.Their structures were determined to be 8-C-α-glucofuranosyl-7,4'-dihydroxyisoflavone and 8-C-β-glucofuranosyl-7,4'-dihydroxy-isoflavone by chemical and spectral analysis. 相似文献
10.
Jie Ju Yu Jin Li Jian Rong Gao Jian Hong Jia Liang Han Wei Jian Sheng Yi Xia Jia 《中国化学快报》2011,22(4):382-384
An aqueous solution of hydrogen peroxide and hydrogen bromide illuminated by a 60 W incandescent light bulb serves as a source of bromine radicals.Various substituted toluenes(NO2,Cl,Br,H,CH3) were high selectively brominated at the benzyl position for monobromination in CH2C12 at ice water with catalyst free.This simple but effective bromination of toluene derivatives with an aqueous H2O2-HBr system is characterized with the use of inexpensive reagents and a lower impact on the environment, which make it a good alternative to the existing bromination methods. 相似文献