全文获取类型
收费全文 | 421篇 |
免费 | 8篇 |
专业分类
化学 | 333篇 |
晶体学 | 7篇 |
力学 | 2篇 |
综合类 | 1篇 |
数学 | 13篇 |
物理学 | 73篇 |
出版年
2021年 | 3篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2013年 | 12篇 |
2012年 | 19篇 |
2011年 | 16篇 |
2010年 | 5篇 |
2009年 | 6篇 |
2008年 | 16篇 |
2007年 | 12篇 |
2006年 | 14篇 |
2005年 | 25篇 |
2004年 | 9篇 |
2003年 | 18篇 |
2002年 | 9篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 14篇 |
1984年 | 16篇 |
1982年 | 10篇 |
1981年 | 15篇 |
1980年 | 8篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1977年 | 3篇 |
1976年 | 9篇 |
1975年 | 9篇 |
1974年 | 12篇 |
1973年 | 14篇 |
1972年 | 3篇 |
1965年 | 3篇 |
1963年 | 2篇 |
排序方式: 共有429条查询结果,搜索用时 31 毫秒
31.
The title compounds and were synthesized by the usual dithia[3.3]phane coupling and photodesulfurization route. Investigation of their physical properties established their molecular dimension and conformation. Transannular interaction disclosed by their electronic spectra was explained by MO calculations. 相似文献
32.
An MR imaging system was developed to visualize brine drainage channels in sea spray icing. Brine pockets trapped in spray-ice matrices during ice growth are structural features of sea spray icing. Brine in the spray ice sample had drained out; therefore, using a suction pump, we filled the air gaps in the drainage channels with dodecane. In the experiments, 0.5-1.0 h was necessary to accumulate signals sufficient to obtain a 3-D micro-image; the image matrix comprised 128(3) voxels (each voxel was 200 microm per side). The MIP view showed that sea spray icing has a developed drainage-channel network structure. 相似文献
33.
34.
[reaction: see text] Polymer-supported bisBINOL ligands were successfully utilized for the immobilization of multicomponent asymmetric catalysts. The polymer-supported Al-Li-bis(binaphthoxide) (ALB) catalyst was more effective than the dendrimer-supported ALB in the Michael reaction of 2-cyclohexen-1-one with dibenzyl malonate affording the adduct in 91% yield with 96% ee. The polymer was also effective for the immobilization of a mu-oxodititanium complex that promoted carbonyl-ene reaction of ethyl glyoxalate with alpha-methyl styrene to provide the adduct with up to 98% ee. 相似文献
35.
Shigeru Odaka Yoshimasa Kurihara 《The European Physical Journal C - Particles and Fields》2007,51(4):867-873
We are developing a consistent method to combine tree-level event generators for hadron collision interactions with those
including one additional QCD radiation from the initial-state partons, based on the limited leading-log (LLL) subtraction
method, aiming at an application to NLO event generators. In this method, a boundary between non-radiative and radiative processes
necessarily appears at the factorization scale (μF). The radiation effects are simulated using a parton shower (PS) in non-radiative processes. It is therefore crucial in our
method to apply a PS which well reproduces the radiation activities evaluated from the matrix-element (ME) calculations for
radiative processes. The PS activity depends on the applied kinematics model. In this paper we introduce two models for our
simple initial-state leading-log PS: a model similar to the ’old’ PYTHIA-PS and a pT-prefixed model motivated by ME calculations. PS simulations employing these models are tested using W-boson production at
LHC as an example. Both simulations show a smooth matching to the LLL subtracted W+1 jet simulation in the pT distribution of W bosons, and the summed pT spectra are stable against a variation of μF, despite that the pT-prefixed PS results in an apparently harder pT spectrum. 相似文献
36.
Yoshiki Kaneoke Masahiro Furuse Suguru Inao Katsuyoshi Saso Kazuo Yoshida Yoshimasa Motegi Motomu Mizuno Akira Izawa 《Magnetic resonance imaging》1987,5(6):415-420
Measurements were made of T1 of bound water (T1b) and bound water fraction () for gelatin solutions and human tissues (sera, brain tumor, cerebral white matter). Bound water fraction in each sample was measured by means of thermal analysis (differential scanning calorimetry: DSC). T1 values were measured by FONAR QED 80-. T1b values were calculated by an equation derived from the fast-exchange two-state model. In the study of gelatin solutions, the relationship between T1 and water content differed depending on the sort of solutions. This was considered to be due to differences in T1b values. In each biological tissue the values of T1b and had different distributions. These results indicate that values of T1b and for biological tissues may be altered in correspondence to the changes in pathophysiological states in those tissues. 相似文献
37.
Yoshimasa Makita Tomofumi Danno Keisuke Ikeda Hsien-Han Lee Taro Abe Kento Sogawa Akihiro Nomoto Shin-ichi Fujiwara Akiya Ogawa 《Tetrahedron letters》2017,58(48):4507-4509
Hemicryptophanes are covalent molecular cages, constructed from a cyclotriveratrylene-based host unit and a functional unit linked by covalent spacers, which have been designed to accommodate endohedral functionalities in the cavity. In this study, the synthesis and characterization of the rigid, biphenyl-linked hemicryptophane 1 were investigated by NMR, ESI-MS, and X-ray crystallography. The structure of the inclusion complex, in which a dichloromethane molecule was constructed encapsulated within 1, was characterized by X-ray crystallography. An endohedral, cobalt(II) hemicryptophane complex 2 was also synthesized and characterized ESI-MS and X-ray crystallography. The X-ray crystal structure of 2 showed that the biphenyl-linked hemicryptophane had three components—a molecule each of chloroform and acetonitrile, and a cobalt(II) ion—within its cavity. 相似文献
38.
Yoshimasa Matsuno 《Physics letters. A》2011,375(34):3090-3094
The N-soliton solution is presented for a two-component modified nonlinear Schrödinger equation which describes the propagation of short pulses in birefringent optical fibers. The solution is found to be expressed in terms of determinants. The proof of the solution is carried out by means of an elementary theory of determinants. The generalization of the 2-component system to the multi-component system is discussed as well as a (2+1)-dimensional nonlocal equation arising from its continuum limit. 相似文献
39.
40.
A moment problem of Hamburger is studied to find a parametric Stieltjes measure from given moments. It is shown that if a deformation, or a dynamics, of moments is governed by a hierarchy of a Kac-van Moerbeke system, then the Stieltjes measure can be constructed explicitly by integrating a hierarchy of Moser's nonlinear dynamical system. The positivity of tau-functions is related to the existence of the Stieltjes measure at a deep level. 相似文献