全文获取类型
收费全文 | 754篇 |
免费 | 35篇 |
专业分类
化学 | 537篇 |
晶体学 | 2篇 |
力学 | 17篇 |
数学 | 116篇 |
物理学 | 117篇 |
出版年
2022年 | 9篇 |
2021年 | 12篇 |
2020年 | 17篇 |
2019年 | 20篇 |
2018年 | 9篇 |
2017年 | 8篇 |
2016年 | 24篇 |
2015年 | 22篇 |
2014年 | 41篇 |
2013年 | 54篇 |
2012年 | 37篇 |
2011年 | 70篇 |
2010年 | 33篇 |
2009年 | 35篇 |
2008年 | 26篇 |
2007年 | 27篇 |
2006年 | 21篇 |
2005年 | 27篇 |
2004年 | 24篇 |
2003年 | 15篇 |
2002年 | 24篇 |
2001年 | 11篇 |
2000年 | 5篇 |
1999年 | 9篇 |
1998年 | 13篇 |
1997年 | 4篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1993年 | 6篇 |
1991年 | 6篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 15篇 |
1984年 | 15篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1977年 | 4篇 |
1976年 | 7篇 |
1975年 | 9篇 |
1974年 | 6篇 |
1971年 | 3篇 |
1969年 | 5篇 |
1968年 | 4篇 |
1967年 | 5篇 |
排序方式: 共有789条查询结果,搜索用时 15 毫秒
51.
Summary We give a general construction of infinite dimensional Ornstein-Uhlenbeck processes. We present expansions of these processes based on the expansion of the covariance operators in generalized eigenfunctions, and we answer positively some question left open by J.B. Walsh on properties of the hitting times of these processes.Partially supported by NSF-Grant MCS 8202045 相似文献
52.
Avcı Davut Altürk Sümeyye Sönmez Fatih Tamer Ömer Başoğlu Adil Atalay Yusuf Zengin Kurt Belma Dege Necmi 《Molecular diversity》2021,25(1):171-189
Molecular Diversity - The World Health Organization (WHO) report shows that diabetes mellitus (DM) will be one of the ten deadly diseases in the near future. The best way to prevent DM is to... 相似文献
53.
Nianjun Yang Rene Hoffmann Waldemar Smirnov Armin Kriele Christoph E. Nebel 《Electrochemistry communications》2010,12(9):1218-1221
Nanotextured diamond surfaces with geometrical properties close to protein dimensions were used for the realization of direct electron transfer of cytochrome c (cyt c) without any covalent bonding. The peroxidase activity of native and denatured cyt c was also investigated. Cyclic voltammograms of native cyt c show quasi-reversible electron transfer reactions, while no heme redox activity is detected for denatured cyt c. Unfolding (denaturation) of cyt c can be achieved in the presence of hydrogen peroxide. Partially or fully denatured cyt c showed higher peroxidase activity than native cyt c. This is because denatured cyt c loses its tertiary structure and hydrogen peroxide is easier to access the heme redox center. The apparent Michaelis–Menten constant Km for native and denatured cyt c has been determined to be 0.23 mM and 0.08 mM. 相似文献
54.
Sebastian Gatz Helge Hannebauer Rene Hesse Florian Werner Arne Schmidt Thorsten Dullweber Jan Schmidt Karsten Bothe Rolf Brendel 《固体物理学:研究快报》2011,5(4):147-149
We demonstrate industrially feasible large‐area solar cells with passivated homogeneous emitter and rear achieving energy conversion efficiencies of up to 19.4% on 125 × 125 mm2 p‐type 2–3 Ω cm boron‐doped Czochralski silicon wafers. Front and rear metal contacts are fabricated by screen‐printing of silver and aluminum paste and firing in a conventional belt furnace. We implement two different dielectric rear surface passivation stacks: (i) a thermally grown silicon dioxide/silicon nitride stack and (ii) an atomic‐layer‐deposited aluminum oxide/silicon nitride stack. The dielectrics at the rear result in a decreased surface recombination velocity of Srear = 70 cm/s and 80 cm/s, and an increased internal IR reflectance of up to 91% corresponding to an improved Jsc of up to 38.9 mA/cm2 and Voc of up to 664 mV. We observe an increase in cell efficiency of 0.8% absolute for the cells compared to 18.6% efficient reference solar cells featuring a full‐area aluminum back surface field. To our knowledge, the energy conversion efficiency of 19.4% is the best value reported so far for large area screen‐printed solar cells. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
55.
B. Wiedemann G. R?dlinger H. Ch. Alt K. G. Heumann K. Bethge 《Fresenius' Journal of Analytical Chemistry》1999,364(8):772-776
The residual or doped element concentration [E] in GaAs measured by SSMS is only accurate with respect to the relative sensitivity
coefficient RSCE. For a trace element concentration, the RSCE = [E]SSMS/[E]TRUE is set to unity, if no reference material or method is available to approximate the concentration to the true value. For
boron a relative sensitivity coefficient of RSCB = 0.94 ± 0.08 was obtained using TI-IDMS as a reference method. RSCN = 1 is used for nitrogen determinations. A boron and nitrogen detection limit of 4.4 × 1013 cm–3 is achieved. SSMS was used as reference method to calibrate the FTIR factor fE = [E] / Iα due to the integrated local vibrational mode absorption Iα of atomic boron and nitrogen in GaAs. A factor of fB = (12.0 × 2.7) × 1016 cm–1 (517 cm–1) and fN = (7.4 ± 0.1) × 1015 cm–1 (472 cm–1) was obtained for a boron and nine nitrogen containing GaAs samples at 77 K and 10 K, respectively.
Received: 15 December 1998 / Revised: 8 April 1999 / Accepted: 13 April 1999 相似文献
56.
57.
58.
59.
60.
Ulrich Jerono Friedrich Alt Jürgen Messerschmidt Günther Tölg 《Mikrochimica acta》1992,108(3-6):221-226
A method for the determination of platinum is presented. The procedure consists of a high-pressure digestion of the sample followed by an ion Chromatographic separation. Then the platinum chloro complex is detected by UV-absorption. 相似文献