全文获取类型
收费全文 | 2754篇 |
免费 | 673篇 |
国内免费 | 1162篇 |
专业分类
化学 | 2195篇 |
晶体学 | 148篇 |
力学 | 228篇 |
综合类 | 130篇 |
数学 | 408篇 |
物理学 | 1480篇 |
出版年
2024年 | 3篇 |
2023年 | 31篇 |
2022年 | 89篇 |
2021年 | 104篇 |
2020年 | 90篇 |
2019年 | 96篇 |
2018年 | 85篇 |
2017年 | 148篇 |
2016年 | 94篇 |
2015年 | 159篇 |
2014年 | 170篇 |
2013年 | 239篇 |
2012年 | 234篇 |
2011年 | 250篇 |
2010年 | 256篇 |
2009年 | 253篇 |
2008年 | 290篇 |
2007年 | 291篇 |
2006年 | 262篇 |
2005年 | 204篇 |
2004年 | 211篇 |
2003年 | 141篇 |
2002年 | 144篇 |
2001年 | 161篇 |
2000年 | 149篇 |
1999年 | 78篇 |
1998年 | 47篇 |
1997年 | 33篇 |
1996年 | 26篇 |
1995年 | 20篇 |
1994年 | 26篇 |
1993年 | 33篇 |
1992年 | 26篇 |
1991年 | 18篇 |
1990年 | 23篇 |
1989年 | 20篇 |
1988年 | 17篇 |
1987年 | 10篇 |
1986年 | 9篇 |
1985年 | 7篇 |
1984年 | 10篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 11篇 |
1979年 | 7篇 |
1978年 | 1篇 |
1974年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有4589条查询结果,搜索用时 15 毫秒
31.
设x:M→Sn 1(n≥3)是n 1-维单位球中的无脐点超曲面, Mobius不变量G,Φ,A和B分别表示x的Mobius度量, Mobius形式, Blaschke形式和Mobius第二基本形式.本文证明了如果x的Mobius形式Φ平行,并且A λG μB=0,其中λ,μ分别是定义在M上的光滑函数,那么Φ=0,由此及李海中、王长平(2003年)文献中的分类定理给出了Sn 1中具有平行的Mobius形式及满足A λG μB=0的超曲面的分类.此结果推广了他们及张廷枋(2003年)文献中的结果. 相似文献
32.
We report a new approach for the self-assembly of cuboid micro-parts onto Si substrates to construct three-dimensional microstructures. To perform assembly, the Si substrates are prepared with a deep cavity array as binding sites. An aggregate composed of hundreds of uniformly aligned micro-parts is formed at the C10F18-H2O interface. The micro-parts are arranged by passing the substrate through the aggregate of micro-parts, thus the micro-parts are left on the substrate, and then the substrate is vibrated ultrasonically in the solution, making it possible for the micro-parts to fall into the cavities on the substrate. Finally the substrate is pulled out of the solution after assembly. This technique could give a high yield of up to 70%, providing a new method for micro-assembly. 相似文献
33.
34.
35.
36.
A novel method for preparing silver nanoelectrode ensembles(SNEEs) and gold nanoelectrode ensembles (GNEEs) has been developed. Silver colloid particles were first absorbed to the gold electrode surface to form a monolayer silver colloid. N-hexadecyl nercaptan was then assembled on the electrode to form a thoil monolayer on which hydrophilic ions cannot be transfered. The SNEEs was prepared by removing thiol from silver colloid surface through applying and AC voltage with increasing frequency at 0.20V(vs.SCE). Finally,GNEEs was obtained by immersing a SNEEs into 6 mol/L HNO3 to remove the silver colloid particles. By comparison with other methods such as template method ect., this method enjoys some advantages of lower resistance, same diameter,easy preparation,controllable size and density. 相似文献
37.
38.
Supermolecular compounds of glycine monosubstituted heteropolytungstates isomer with Keggin structure βi-K6-n(HGly)n[SiW11M(H2O)O39]·xH2O (M=Co2+, Ni2+; βi=β2, β3) were synthesized and characterized by means of elementary analysis, IR, UV, TG-DTA, X-ray diffraction, polarography and CV. The results indicate that glycin combines the electrostatic effect with heteropolytungstates isomer. The heteropoly anion still remains its Keggin structure in supermolecular compounds. The electrochemical behavior of the compound in 1 mol·L-1 HAc-NaAc shows that two redox waves correspond to two two-electron processes attributing to the reduction of [SiW11Co(H2O)O39]6-. Steady-state fluorescence spectrum shows two intenser fluorescence emission peaks in 447 nm and 486 nm appeared after the supermolecular compound being excited by the excitation wavelength in 274 nm. 相似文献
39.
IntroductionElectrontransferreactionsarethekeystepsinphoto synthesis ,respirationandmanyotherbiochemicalprocess es.1Cytochromeb5isaredoxproteinexistingwidelyinnature ,whichactsasanelectron carrierduringvariouselectrontransferprocessesinthebiologicalsystem .2Cytochromeb5isamembraneproteinwithmolecularweightofapproximately 16kDa ,ofwhichthehydrophobicC terminaldomainanchorscytochromeb5tothemem brane ,andthehydrophilicN terminaldomaincontainshemeprostheticgroupandexhibitsthebiologicalfunctionsof… 相似文献
40.