全文获取类型
收费全文 | 2148篇 |
免费 | 51篇 |
国内免费 | 8篇 |
专业分类
化学 | 1606篇 |
晶体学 | 10篇 |
力学 | 29篇 |
数学 | 219篇 |
物理学 | 343篇 |
出版年
2023年 | 9篇 |
2022年 | 42篇 |
2021年 | 103篇 |
2020年 | 45篇 |
2019年 | 62篇 |
2018年 | 80篇 |
2017年 | 51篇 |
2016年 | 77篇 |
2015年 | 82篇 |
2014年 | 69篇 |
2013年 | 181篇 |
2012年 | 90篇 |
2011年 | 116篇 |
2010年 | 110篇 |
2009年 | 91篇 |
2008年 | 124篇 |
2007年 | 137篇 |
2006年 | 98篇 |
2005年 | 103篇 |
2004年 | 66篇 |
2003年 | 75篇 |
2002年 | 54篇 |
2001年 | 26篇 |
2000年 | 25篇 |
1999年 | 26篇 |
1998年 | 22篇 |
1997年 | 22篇 |
1996年 | 27篇 |
1995年 | 8篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1992年 | 18篇 |
1991年 | 14篇 |
1989年 | 7篇 |
1988年 | 12篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1982年 | 6篇 |
1980年 | 5篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 8篇 |
1974年 | 5篇 |
1973年 | 7篇 |
1972年 | 7篇 |
1970年 | 4篇 |
1969年 | 7篇 |
排序方式: 共有2207条查询结果,搜索用时 250 毫秒
11.
Girard V Farrenq R Sorokin E Sorokina IT Guelachvili G Picqué N 《Chemical physics letters》2006,419(4-6):584-588
The spectral dynamics of a mid-infrared multimode Cr(2+):ZnSe laser located in a vacuum sealed chamber containing acetylene at low pressure is analyzed by a stepping-mode high-resolution time-resolved Fourier transform interferometer. Doppler-limited absorption spectra of C(2)H(2) in natural isotopic abundance are recorded around 4000 cm(-1) with kilometric absorption path lengths and sensitivities better than 3 10(-8) cm(-1). Two cold bands are newly identified and assigned to the ν(1)+ν(4) (1) and ν(3)+ν(5) (1) transitions of (12)C(13)CH(2). The ν(1)+ν(5) (1) band of (12)C(2)HD and fourteen (12)C(2)H(2) bands are observed, among which for the first time ν(2)+2ν(4) (2)+ν(5) (-1). 相似文献
12.
In this work actin is used to illustrate connection of protein fluorescence characteristics with its structure. On one hand, it has been demonstrated what kind of information about the contribution of each tryptophan residues to the bulk fluorescence spectrum can be obtained from the special analysis of protein three-dimensional structure. On the other hand, potentials of intrinsic fluorescence for elucidation of proteins structure, dynamics and processes of folding-unfolding are shown. In particular, using this method a new essentially unfolded kinetic intermediate state of actin was detected and characterized, and the place of inactivated actin and its kinetic predecessor in the process of folding-unfolding was determined. It has been revealed that inactivated actin is not intermediate state between the native and completely unfolded states, as it has been accepted before, but a result of protein misfolding. On the basis of the obtained data a new model of actin folding-unfolding pathway has been proposed. 相似文献
13.
14.
Nowadays much attention is being paid to the determination of trace amounts of noble metals in geological, industrial, biological and environmental samples. The most promising techniques, such as inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS) and electrothermal atomic absorption spectrometry (ETAAS) are characterized by high sensitivity. However, the accurate determination of trace noble metals has been limited by numerous interferences generated from the presence of matrix elements. To decrease, or eliminate, these interferences, the sorption preconcentration of noble metals is often used prior to their instrumental detection. A great number of hyphenated methods of noble metal determination using sorption preconcentration have been developed. This review describes the basic types of available sorbents, preconcentration procedures and preparations of the sorbent to the subsequent determination of noble metals. The specific features of instrumental techniques and examples of ETAAS, FAAS, ICP-AES, ICP-MS determinations after the sorption preconcentration of noble metals are considered. The references cited here were selected mostly from the period 1996 - 2006. 相似文献
15.
16.
V. P. Nesterenko K. P. Aref'ev V. I. Merkulov A. A. Kondratyuk A. V. Petrov 《Russian Physics Journal》2003,46(2):157-160
The electric strength of a polyoxide mass obtained on the surface of hard alloy composite materials by their high-temperature heating in an electric furnace with direct access of atmospheric air is studied. 相似文献
17.
We study the Besov regularity of conformal mappings for domains with rough boundary based on the well-posedness for the Dirichlet problem with Besov data. Also, sharp invertibility results for the classical layer potential operators on Sobolev-Besov spaces on the boundary of curvilinear polygons are obtained. 相似文献
18.
Irina Markina 《Journal of Functional Analysis》2007,245(2):475-492
We consider coefficient bodies Mn for univalent functions. Based on the Löwner-Kufarev parametric representation we get a partially integrable Hamiltonian system in which the first integrals are Kirillov's operators for a representation of the Virasoro algebra. Then Mn are defined as sub-Riemannian manifolds. Given a Lie-Poisson bracket they form a grading of subspaces with the first subspace as a bracket-generating distribution of complex dimension two. With this sub-Riemannian structure we construct a new Hamiltonian system to calculate regular geodesics which turn to be horizontal. Lagrangian formulation is also given in the particular case M3. 相似文献
19.
Irina N. Savina Bo Mattiasson Igor Yu. Galaev 《Journal of polymer science. Part A, Polymer chemistry》2006,44(6):1952-1963
Graft polymerization initiated by diperiodatocuprate(III) complex (Cu(III)) initiator was found to be an effective and convenient method for graft polymerization of vinyl monomers onto macroporous polyacrylamide gels, the so‐called cryogels (pAAm‐cryogels). The effect of time, temperature, monomer and initiator concentration during the graft polymerization in aqueous and aqueous‐organic media was studied. The graft polymerization of water‐soluble monomers as [2‐(methacryloyloxy)ethyl]‐trimethylammonium chloride, 2‐hydroxyethyl methacrylate, N‐isopropylacrylamide, and N,N‐dimethylacrylamide proceeds with higher grafting yield in aqueous medium, as compared with that in aqueous‐organic media. Graft polymerization in aqueous‐organic media such as water–DMSO solutions allows grafting of water‐insoluble monomers such as glycidyl methacrylate and N‐tert‐butylacrylamide with high grafting degrees of 100 and 410%, respectively. It was found that the deposition of initiator on the pore surface of cryogels promoted graft polymerization by facilitating the formation of the redox couple Cu(III)‐acrylamide group. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1952–1963, 2006 相似文献
20.
Irina P. Beletskaya 《Journal of organometallic chemistry》2004,689(24):4055-4082
The application of palladacycles as catalysts for cross-coupling and similar reactions is reviewed. In the majority of cases palladacycles are likely to serve as a source of highly active but unstable zero-valent palladium species. In this respect the palladacycles resemble the so-called phosphine-free catalysts. The advantages and limitations of palladacycle catalysts are discussed. 相似文献