全文获取类型
收费全文 | 67篇 |
免费 | 30篇 |
国内免费 | 5篇 |
专业分类
化学 | 37篇 |
综合类 | 1篇 |
数学 | 44篇 |
物理学 | 20篇 |
出版年
2022年 | 1篇 |
2014年 | 2篇 |
2013年 | 5篇 |
2011年 | 1篇 |
2009年 | 4篇 |
2008年 | 1篇 |
2007年 | 2篇 |
2004年 | 2篇 |
2002年 | 1篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 7篇 |
1982年 | 1篇 |
1981年 | 6篇 |
1980年 | 1篇 |
1978年 | 4篇 |
1977年 | 1篇 |
1974年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1956年 | 1篇 |
1955年 | 1篇 |
1948年 | 14篇 |
1947年 | 1篇 |
排序方式: 共有102条查询结果,搜索用时 15 毫秒
21.
22.
RAYMOND D. MILLER SATYA PRAKASH† LOUISE PRAKASH † 《Photochemistry and photobiology》1984,39(3):349-352
Abstract— The RAD1, RAD2, RAD3 and RAD4 genes of Saccharomyces cerevisiae are required for incising DNA containing UV induced pyrimidine dimers or psoralen plus 360 nm light induced interstrand crosslinks. We have now determined if these genes are also required for incising DNA at psoralen plus 360 nm light induced monoadducts. For distinguishing between incision breaks occurring at crosslinks and at monoadducts. we have used the cdc9-2 mutant, defective in DNA ligase activity at the restrictive temperature, and the radl-2 cdc9-2, rad2-5 cdc9-2 , rad3-2 cdc9-2 and rad4-4 cdc9-2 double mutant combinations. We conclude that the radl, rad2 , and rad4 mutants are defective in incising DNA both at crosslinks and monoadducts, whereas the rad3 mutant is proficient in incising DNA at monoadducts but not at crosslinks. 相似文献
23.
ter Steege DH Smits M de Lange CA Westwood NP Peel JB Visscher L 《Faraday discussions》2000,(115):259-69; discussion 303-30
A (2 + 1) one-colour resonance-enhanced multiphoton ionisation study is carried out on the C 2 sigma- state of the ClO radical in the one-photon energy range 29,500-31,250 cm-1. The ClO radical is produced by one-photon photolysis of ClO2 employing 359.2 nm photons derived from a separate laser. In this way a significant concentration of vibrationally excited ClO in its spin-orbit split X 2 pi omega (omega = 3/2 or 1/2) electronic ground state is produced. In addition to mass-resolved excitation spectra, kinetic-energy resolved photoelectron spectra for the X 3 sigma-(v+)<--C 2 sigma-(v' = 3-5) transitions are measured. These transitions are not completely Frank-Condon diagonal, and indicate a decrease in bond length on removal of the Rydberg electron from the C 2 sigma- state. In addition to an unambiguous assignment of the C 2 sigma- state, valuable information is obtained on the degree of vibrational excitation with which the nascent ClO radical is formed in the photolysis of ClO2. Analysis of the photoelectron spectra is supported by Franck-Condon calculations based on potential energy curves either from experimental spectroscopic parameters, or obtained by theoretical ab initio methods. 相似文献
24.
S. RANDY HOLMES-FARLEY W. HARRY MANDEVILLE J. WARD K. L. MILLER 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(7-8):1085-1091
ABSTRACT Sevelamer hydrochloride (polyallylamine crosslinked with epichlorohydrin) is a polymeric hydrogel that has been developed as an oral pharmaceutical to prevent the absorption of dietary phosphate by kidney dialysis patients. It has been found to bind to phosphate in vitro, and to do so more effectively than a wide range of other cationic polymers. It shows a preference for phosphate over other intestinal anions, such as chloride and bicarbonate. The preference for phosphate is believed to be due to its dianion character, and may also involve hydrogen bonding. The absorption of phosphate in vitro is rapid (less than a minute) relative to the time of passage of such a drug through the small intestine (hours). It has also been found to prevent the absorption of dietary phosphate in vivo and in humans, and is presently awaiting FDA approval. 相似文献
25.
26.
27.
28.
PARALLEL AUXILIARY SPACE AMG FOR H(curl) PROBLEMS 总被引:2,自引:0,他引:2
In this paper we review a number of auxiliary space based preconditioners for the second order definite and semi-definite Maxwell problems discretized with the lowest order Nedelec finite elements. We discuss the parallel implementation of the most promising of these methods, the ones derived from the recent Hiptmair-Xu (HX) auxiliary space decomposition [Hiptmair and Xu, SIAM J. Numer. Anal., 45 (2007), pp. 2483-2509]. An extensive set of numerical experiments demonstrate the scalability of our implementation on large-scale H(curl) problems. 相似文献
29.
能带是决定固体特性的头等重要的因素。我们用光谱方法对单相YBa2Cu2Ox高T。超导体进行了研究,测量了样品的反射-吸收谱、Raman光谱和荧光光谱.其350和500nm吸收带以及390nm,560nm荧光峰来自晶格中Cu+发光中心,是跃迁过程1A1g(3d10)-1Eg和~3Eg(3d94s1)。其720nm和860nm荧光峰来自Cu2+发光中心,是由于自由离子光谱项2D在八面体晶场、正交晶系晶场中分裂为5个能级之间的跃迁。此外,还有一些光谱可能来自晶格中Cu3+发光中心,其481cm-1和551cm-1声子对说明了312cm-1处声子对与电子系统是强耦合。 相似文献
30.