全文获取类型
收费全文 | 1554篇 |
免费 | 33篇 |
国内免费 | 8篇 |
专业分类
化学 | 868篇 |
晶体学 | 25篇 |
力学 | 16篇 |
数学 | 192篇 |
物理学 | 494篇 |
出版年
2022年 | 9篇 |
2021年 | 10篇 |
2020年 | 11篇 |
2019年 | 8篇 |
2018年 | 14篇 |
2016年 | 18篇 |
2015年 | 24篇 |
2014年 | 33篇 |
2013年 | 63篇 |
2012年 | 56篇 |
2011年 | 67篇 |
2010年 | 54篇 |
2009年 | 38篇 |
2008年 | 54篇 |
2007年 | 58篇 |
2006年 | 44篇 |
2005年 | 46篇 |
2004年 | 70篇 |
2003年 | 36篇 |
2002年 | 30篇 |
2001年 | 35篇 |
2000年 | 29篇 |
1999年 | 22篇 |
1998年 | 25篇 |
1997年 | 29篇 |
1996年 | 43篇 |
1995年 | 35篇 |
1994年 | 35篇 |
1993年 | 22篇 |
1992年 | 21篇 |
1991年 | 24篇 |
1990年 | 26篇 |
1989年 | 36篇 |
1988年 | 20篇 |
1987年 | 18篇 |
1986年 | 28篇 |
1985年 | 28篇 |
1984年 | 32篇 |
1983年 | 26篇 |
1982年 | 28篇 |
1981年 | 22篇 |
1980年 | 14篇 |
1979年 | 29篇 |
1978年 | 23篇 |
1977年 | 10篇 |
1976年 | 26篇 |
1975年 | 12篇 |
1974年 | 34篇 |
1973年 | 21篇 |
1972年 | 14篇 |
排序方式: 共有1595条查询结果,搜索用时 312 毫秒
1.
Stefan Peterli Dieter Hubmann Urs Squin Helmut Mett Peter Traxler 《Helvetica chimica acta》1994,77(1):59-69
β-Nitrostyrene derivatives of adenosine 5′-glutarates are potent and selective bisubstrate-type inhibitors of the epidermal growth factor receptor protein tyrosine kinase (EGF-R PTK). In an attempt to improve the inhibitory activity, this type of compounds was modified with alkyl spacers of varying length between the nitrostyrene and the glutaryl units. The spacers consisted of 1, 3, 4, and 5 atoms to give compounds of the benzyl, oxyethyl, oxypropyl, and oxybutyl series, respectively (Schemes 1 and 2). Adenosine 5′-esters were prepared in the benzyl and oxypropyl series only. Compared to the compounds in the parent series without spacer (IC50 = 0.7–12 μM ), most of the modified compounds inhibited the EGF-R PTK only marginally or were inactive (IC50 ≥ 100 μM ). The only exceptions were the free acids 19 and 20 with IC50 values of ca. 5 μM . It is noteworthy that esterification of these two hydrogen glutarates with either MeOH or adenosine yielded inactive compounds, which is in contrast to the corresponding substances without spacers. 相似文献
2.
3.
We have calculated inclusive two-jet cross sections in next-to-leading order QCD for low Q 2 ep collisions superimposing direct and resolved contributions. Infrared and collinear singularities in the virtual and real contributions are cancelled with the phase space slicing method. Various inclusive two-jet distributions have been computed. The results are compared with recent data from the ZEUS collaboration at HERA. 相似文献
4.
Jürg Kramer 《Elemente der Mathematik》2002,57(3):115-120
5.
6.
Utilizing forward recoil spectrometry (FRES), we have determined the segregation isotherm which describes the interfacial excess zi* of diblock copolymers of poly (d8-styrene-b-2-vinylpyridine) (dPS-PVP) at the interface between the homopolymers PS and PVP as a function of ?∞, the volume fraction of diblock copolymer remaining in the host homopolymer. All the samples were analyzed after annealing at temperatures and times sufficient to achieve equilibrium segregation. The effect of the degree of polymerization of both the diblock copolymers and the host homopolymers on the segregation isotherm is investigated. When the degree of polymerization of the homopolymer is much larger than that of the diblock copolymer, the normalized interfacial excess (zi*/Rg), where Rg is the radius of gyration of an isolated block copolymer chain, is a universal function of that portion of the block copolymer chemical potential due to chain stretching. The existence of such a universal function is predicted by theory and its form is in good agreement with self-consistent mean field calculations. Using these results, one can predict important aspects of the block copolymer segregation (e.g., the saturation interfacial excess) without recourse to the time-consuming numerical calculations. © 1994 John Wiley & Sons, Inc. 相似文献
7.
Urs Lang 《Mathematische Zeitschrift》1992,210(1):581-592
8.
Sangcheol Kim Frdric S. Diana Pierre M. Petroff Edward J. Kramer Takeshi Ootsu Tomohide Murase 《Journal of Polymer Science.Polymer Physics》2006,44(22):3227-3233
The encapsulation of the nanocrystalline manganese‐doped zinc sulfide (ZnS:Mn) in poly(styrene‐b‐2vinylpyridine) (PS‐PVP) diblock copolymers is reported. Below the critical micelle concentration in the absence of nanocrystals (NCs), inverse micelles of PS‐PVP were induced by adding ZnS:Mn NCs, the presence of which was confirmed by scanning force microscope and dynamic light scattering. In toluene, a PS‐selective solvent, the less‐soluble PVP blocks preferentially surround the ligand‐coated ZnS:Mn NCs. For PS‐PVP encapsulated ZnS:Mn NCs, the ratio of blue emission to orange emission of ZnS:Mn NCs is dependent on both the concentration of PS‐PVP and the solvent quality. The pyridine of PVP blocks form complexes with the Zn atoms via the nitrogen lone pair and thus the sulfur vacancies are passivated. As a result, the defect‐related blue emission is selectively quenched even when the micelles are not formed. As the concentration of PS‐PVP encapsulating the ZnS:Mn NCs increases, the intensity of blue emission decreases. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3227–3233, 2006 相似文献
9.
F. T. Brandt G. Kramer Su-Long Nyeo 《Zeitschrift fur Physik C Particles and Fields》1990,48(2):301-308
We calculate cross sections for the production ofW + andZ bosons in association with 1 and 2 jets at \(p\bar p\) collider energies. The expected rates for these processes in second-order QCD are presented as a function of the cuts on the transverse momenta of the jets and are compared with jet rates measured by UA1. 相似文献
10.
We study the pattern of soft parton radiation in the hard annihilation processes \(e^ + e^ - \to q\bar q\gamma \) and \(e^ + e^ - \to q\bar qg\) by explicit evaluation of the cross sections for \(e^ + e^ - \to q\bar q\gamma g\) and \(e^ + e^ - \to q\bar qgg + q\bar qq\bar q\) taken care of correct normalization. We find the coherence effects as observed experimentally and discuss why these effects are not present in the usual models based onO(α s 2 ) perturbation theory with subsequent independent fragmentation. 相似文献