全文获取类型
收费全文 | 454篇 |
免费 | 7篇 |
国内免费 | 4篇 |
专业分类
化学 | 229篇 |
晶体学 | 9篇 |
力学 | 20篇 |
数学 | 24篇 |
物理学 | 183篇 |
出版年
2021年 | 3篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 10篇 |
2013年 | 12篇 |
2012年 | 8篇 |
2011年 | 16篇 |
2010年 | 11篇 |
2009年 | 6篇 |
2008年 | 12篇 |
2007年 | 24篇 |
2006年 | 24篇 |
2005年 | 13篇 |
2004年 | 11篇 |
2003年 | 9篇 |
2002年 | 15篇 |
2001年 | 10篇 |
2000年 | 19篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1996年 | 4篇 |
1995年 | 11篇 |
1994年 | 9篇 |
1993年 | 23篇 |
1992年 | 20篇 |
1991年 | 7篇 |
1990年 | 14篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 12篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1980年 | 8篇 |
1979年 | 9篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1968年 | 4篇 |
1936年 | 2篇 |
1934年 | 3篇 |
1933年 | 2篇 |
1929年 | 2篇 |
1927年 | 2篇 |
1917年 | 4篇 |
1890年 | 2篇 |
1889年 | 2篇 |
1885年 | 2篇 |
排序方式: 共有465条查询结果,搜索用时 296 毫秒
1.
Effect of additive length and chemistry on the morphology of blends of conjugated thiophenes and fullerene derivative acceptor molecules 下载免费PDF全文
Small molecule additives have been shown to increase the device efficiency of conjugated polymer (donor) and fullerene derivative (acceptor) based organic solar cells by modifying the morphology of the device active layer. In this paper we conduct a systematic study of how additives affect the donor‐acceptor morphology using molecular dynamics simulations of blends of thiophene‐based oligomers, mimicking poly(3‐dodecylthiophene) (P3DDT) or poly(2,2′:5′,2”‐3,3”‐didocyl‐terthiophene) (PTTT), and fullerene derivatives with additives of varying length and chemical functionalization, mimicking experimentally used additives like methyl ester additives, diiodooctane, and alkanedithiols. We find that functionalization of additives with end groups that are attracted to acceptor molecules are necessary to induce increased donor‐acceptor macrophase separation. In blends where acceptors intercalate between oligomer alkyl side chains, functionalized additives decrease acceptor intercalation. Functionalized additives with shorter alkyl segments increase acceptor macrophase separation more than additives with same chemical functionalization but longer alkyl segments. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1046–1057 相似文献
2.
The results of Monte Carlo simulations of the beta dose rate to enamel are presented. The dose rates are the most comprehensive to date, incorporating the beta spectrum from 21 different radionuclides, all internal conversion and Auger electrons, the majority of the bremsstrahlung radiation, effects due to radon loss in the uranium series, and variations in the moisture content of the sediment. Applications to a new dating technique in archaeology using electron spin resonance and beta-gradient isochrons are discussed. 相似文献
3.
Y. Huang D.J.H. Cockayne C. Marsh J.M. Titchmarsh A.K. Petford-Long 《Applied Surface Science》2005,252(5):1954-1958
A method using a focused ion beam (FIB) to prepare a silicon amorphous material is presented. The method involves the redeposition of sputtered material generated during the interaction of the Ga+ ion beam with a silicon substrate material. The shape and dimensions of this amorphous material are self-organized and reproducible. The stability of this amorphous material under electron irradiation was investigated in the transmission electron microscopy (TEM). Electron irradiation can induce recrystallization of the amorphous material, resulting in the lateral and vertical growth, starting at an amorphous-crystalline interface, of polysilicon containing defects. 相似文献
4.
Suzanne J. Dilly Steven J. Carlisle Andrew J. Clark Andrew R. Shepherd Stephen C. Smith Paul C. Taylor Andrew Marsh 《Journal of polymer science. Part A, Polymer chemistry》2006,44(7):2248-2259
A practical and divergent synthesis of supported [1,3,5]‐triazine dendritic molecules on Wang resin, PEGA resin, SynPhase? Lanterns, and silica gel is described. The alkylamine linkers used allow derivatization with functionality for both synthetic (e.g., supported reagent and scavenger activity) and chemical biology applications. The use of supported intermediates allows differentiation of symmetric linkers without the need for protecting group chemistry. The synthetic route uses inexpensive, readily available starting materials in a straightforward and scaleable strategy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2248–2259, 2006 相似文献
5.
At the ISOLDE on-line isotope separation facility, the resonance ionisation laser ion source (RILIS) can be used to ionise
reaction products as they effuse from the target. The RILIS process of laser step-wise resonance ionisation of atoms in a
hot metal cavity provides a highly element selective stage in the preparation of the radioactive ion beam. As a result, the
ISOLDE mass separators can provide beams of a chosen isotope with greatly reduced isobaric contamination. With the addition
of a new three-step ionisation scheme for gold, the RILIS is now capable of ionising 26 of the elements. The optimal scheme
was determined during an extensive study of the atomic energy levels and auto-ionising states of gold, carried out by means
of in-source resonance ionisation spectroscopy. Details of the ionisation scheme and a summary of the spectroscopy study are
presented. 相似文献
6.
7.
8.
Mishra SR Bachmann KT Bernstein RH Blair RE Foudas C Lefmann WC Leung WC Oltman E Quintas PZ Sciulli FJ Shaevitz MH Smith WH Merritt FS Oreglia MJ Schellman H Schumm BA Borcherding F Fisk HE Lamm MJ Marsh W Merritt KW Yovanovitch DD Bodek A Budd HS Sakumoto WK 《Physical review letters》1989,63(2):132-135
9.
10.
J. M. Beiriger R. A. Failor K. V. Marsh G. E. Shaw 《Journal of Radioanalytical and Nuclear Chemistry》1988,123(1):21-37
Following the accident at the nuclear reactor at Chernobyl, in the Soviet Union on April 26, 1986, we performed a variety of measurements to determine the level of the radioactive fallout on the western United States. We used gamma-spectroscopy to analyze air filters from the areas around Lawrence Livermore National Laboratory (LLNL), California, and Barrow and Fairbanks, Alaska. Milk from California and imported vegetables were also analyzed. The levels of the various fission products detected were far below the maximum permissable concentration levels.Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-48. 相似文献