全文获取类型
收费全文 | 412篇 |
免费 | 7篇 |
国内免费 | 9篇 |
专业分类
化学 | 145篇 |
晶体学 | 5篇 |
力学 | 24篇 |
数学 | 75篇 |
物理学 | 179篇 |
出版年
2022年 | 8篇 |
2021年 | 9篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 9篇 |
2017年 | 7篇 |
2016年 | 12篇 |
2015年 | 7篇 |
2014年 | 47篇 |
2013年 | 33篇 |
2012年 | 41篇 |
2011年 | 36篇 |
2010年 | 23篇 |
2009年 | 13篇 |
2008年 | 21篇 |
2007年 | 21篇 |
2006年 | 18篇 |
2005年 | 10篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1989年 | 3篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1983年 | 6篇 |
1982年 | 1篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1963年 | 2篇 |
1960年 | 1篇 |
1945年 | 1篇 |
1944年 | 1篇 |
1942年 | 1篇 |
排序方式: 共有428条查询结果,搜索用时 15 毫秒
421.
Shah R. ALI Prakash CHANDRA Mamta LATWAL Shalabh K. JAIN Vipin K. BANSAL Sudhanshu P. SINGH 《催化学报》2011,(12):1844-1849
Nickel hexacyanoferrate nanoparticles were synthesized and characterized using elemental analysis, thermal analysis, infrared spectroscopy, and X-ray diffraction. A FE-SEM image of the nickel hexacyanoferrate showed that it consists of nearly spherical particles with sizes ranging from 30 to 70 nm. The synthesized material was found to be a heterogeneous catalyst useful for the solvent-free oxidation of benzyl alcohol with H2O2 as an oxidant. A 36% conversion of benzyl alcohol to benzaldehyde was achieved under optimized reaction conditions using specific parameters such as the amount of catalyst, the temperature, the benzyl alcohol to H2O2 molar ratio, and the reaction time. 相似文献
422.
Tan A Balachandran J Sadat S Gavini V Dunietz BD Jang SY Reddy P 《Journal of the American Chemical Society》2011,133(23):8838-8841
We present a combined experimental and computational study that probes the thermoelectric and electrical transport properties of molecular junctions. Experiments were performed on junctions created by trapping aromatic molecules between gold electrodes. The end groups (-SH, -NC) of the aromatic molecules were systematically varied to study the effect of contact coupling strength and contact chemistry. When the coupling of the molecule with one of the electrodes was reduced by switching the terminal chemistry from -SH to -H, the electrical conductance of molecular junctions decreased by an order of magnitude, whereas the thermopower varied by only a few percent. This has been predicted computationally in the past and is experimentally demonstrated for the first time. Further, our experiments and computational modeling indicate the prospect of tuning thermoelectric properties at the molecular scale. In particular, the thiol-terminated aromatic molecular junctions revealed a positive thermopower that increased linearly with length. This positive thermopower is associated with charge transport primarily through the highest occupied molecular orbital, as shown by our computational results. In contrast, a negative thermopower was observed for a corresponding molecular junction terminated by an isocyanide group due to charge transport primarily through the lowest unoccupied molecular orbital. 相似文献
423.
Vikram S. Bajaj Melody L. Mak-Jurkauskas Marina Belenky Judith Herzfeld Robert G. Griffin 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2010,202(1):9-13
We describe a new approach to multiple 13C–15N distance measurements in uniformly labeled solids, frequency-selective (FS) TEDOR. The method shares features with FS-REDOR and ZF- and BASE-TEDOR, which also provide quantitative 15N–13C spectral assignments and distance measurements in U-[13C,15N] samples. To demonstrate the validity of the FS-TEDOR sequence, we measured distances in [U-13C,15N]-asparagine which are in good agreement with other methods. In addition, we integrate high frequency dynamic nuclear polarization (DNP) into the experimental protocol and use FS-TEDOR to record a resolved correlation spectrum of the Arg-13Cγ–15Nε region in [U-13C,15N]-bacteriorhodopsin. We resolve six of the seven cross-peaks expected based on the primary sequence of this membrane protein. 相似文献
424.
We discuss the use of two alternative design techniques for enhancing the performance of nanocrystalline Si solar cells. The first technique involves the use of alternating layers of nanocrystalline and amorphous silicon, where the amorphous silicon layer is used to effectively passivate the grain boundaries in nano Si. We show that the use of amorphous Si layer increases photon absorption and leads to higher quantum efficiency in infrared wavelength. The second design involves enhancing the grains in nano Si by growing at higher temperatures, followed by anneal in a hydrogen plasma to preserve grain boundary passivation. This technique results in significant improvement in infrared quantum efficiency of solar cells while preserving good electronic properties. 相似文献
425.
Rasheed Tabish Siddiqui Shamoon Ahmad Kargeti Ankit Shukla Dharmesh Vikram Singh Vijay Pandey Anoop Kumar 《Structural chemistry》2021,32(6):2209-2221
Structural Chemistry - Unique superhalogen properties of Pt(CN)n complexes (n = 1–6) have been investigated under the quantum chemical formalism. The study involves theoretical calculations... 相似文献
426.
Vikram Venugopalarao Amperayani Karteek rao Ummidi Venkata Ravi Sankar Parimi Umadevi 《Russian Journal of General Chemistry》2021,91(12):2483-2488
Russian Journal of General Chemistry - A series of novel N-pyridine substituted 2-chloro-thieno[2,3-d]pyrimidin-4-amine derivatives has been synthesized and characterized by 1H and 13C NMR... 相似文献
427.
428.