首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   275篇
  免费   20篇
  国内免费   2篇
化学   231篇
晶体学   1篇
数学   3篇
物理学   62篇
  2023年   5篇
  2022年   6篇
  2021年   12篇
  2020年   10篇
  2019年   14篇
  2018年   8篇
  2017年   8篇
  2016年   12篇
  2015年   13篇
  2014年   8篇
  2013年   19篇
  2012年   18篇
  2011年   28篇
  2010年   8篇
  2009年   8篇
  2008年   17篇
  2007年   11篇
  2006年   11篇
  2005年   11篇
  2004年   5篇
  2003年   5篇
  2002年   4篇
  2001年   4篇
  1999年   2篇
  1996年   4篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1990年   1篇
  1989年   1篇
  1987年   1篇
  1986年   2篇
  1985年   2篇
  1984年   4篇
  1983年   1篇
  1982年   3篇
  1980年   4篇
  1979年   1篇
  1978年   3篇
  1977年   3篇
  1976年   3篇
  1975年   4篇
  1974年   1篇
  1973年   1篇
  1972年   1篇
  1969年   1篇
  1968年   2篇
  1966年   1篇
  1963年   1篇
排序方式: 共有297条查询结果,搜索用时 15 毫秒
131.
We comparatively analyzed and quantitatively evaluated the field of view and the viewing zone of single-shot phaseshifting digital holography that uses space-division multiplexing, for the first time. We formulated the sampling intervals in the techniques in which the phase of the reference wave is spatially divided into two and four steps, and numerically simulated the areas. It was clarified that each area of the spatial two-step phase-shifting technique was twice as wide as that of the spatial four-step phase-shifting technique. We also experimentally investigated the areas. The ghost appeared for the spatial four-step technique when the object was between the boundary of the field of view of the spatial two-step technique and that of the spatial four-step technique, but did not appear for the spatial two-step technique.  相似文献   
132.
Catalytic C?H borylation has been reported using newly designed iron complexes bearing a 4,5,6,7‐tetrahydroisoindol‐2‐ide‐based PNP pincer ligand. The reaction tolerated various five‐membered heteroarenes, such as pyrrole derivatives, as well as six‐membered aromatic compounds, such as toluene. Successful examples of the iron‐catalyzed sp3 C?H borylation of anisole derivatives were also presented.  相似文献   
133.
Mechanical anisotropy is an essential property for biomolecules to assume structural and functional roles in mechanobiology. However, there is insufficient information on the mechanical anisotropy of ligand–biomolecule complexes. Herein, we investigated the mechanical property of individual human telomeric G‐quadruplexes bound to telomestatin, using optical tweezers. Stacking of the ligand to the G‐tetrad planes changes the conformation of the G‐quadruplex, which resembles a balloon squeezed in certain directions. Such a squeezed balloon effect strengthens the G‐tetrad planes, but dislocates and weakens the loops in the G‐quadruplex upon ligand binding. These dynamic interactions indicate that the binding between the ligand and G‐quadruplex follows the induced‐fit model. We anticipate that the altered mechanical anisotropy of the ligand–G‐quadruplex complex can add additional level of regulations on the motor enzymes that process DNA or RNA molecules.  相似文献   
134.
Molecular Diversity - Druglikeness is a useful concept for screening drug candidate compounds. We developed QEX, which is a new druglikeness index specific to individual targets. QEX is an...  相似文献   
135.
ABSTRACT

We present a simple coarse-grained model in which each amino acid residue is represented by one coarse-grained particle for interacting protein complex. In order to determine the coarse-grained potential function of the interaction between amino acid residues, free energy profile as a function of the distance between amino acid side chains is investigated by using all-atom molecular dynamics simulations with thermodynamic integration method. The Langevin dynamics simulation with Gō-like model and our coarse-grained model reproduces homotetramer complex structure of GCN4-pLI and shows that interaction between hydrophobic amino acid residues promote the association of GCN4-pLI monomers.  相似文献   
136.
Orientation-controlled anisotropic diffraction gratings are realized by interferometric exposure using composite materials of nematic liquid crystals (LCs) and LC diacrylate monomers. The anisotropic diffraction properties in volume gratings, which dominantly diffract p- or s-polarized light, are shown to be controlled by the rubbed directions of the alignment layers under the control of the photopolymerization temperature. Images of the fringe patterns observed by polarization microscopy show the effects of the alignment layers on the LC orientation during grating formation.  相似文献   
137.
The reduction of fullerene (C60) with sodium dispersion in the presence of an excess amount of dipropyl sulfate was found to yield highly propylated fullerene, C60(nC3H7)n (max. n = 24), and C60(nC3H7)20 was predominantly generated as determined by mass spectroscopy.  相似文献   
138.
We have investigated the effect of antiplasticization on the stress‐optical behavior of polycarbonate (PC) containing terphenyls (tPh) and di(2‐ethylhexyl)adipate (DEHA). Addition of the three tPhs (p‐, o‐, and m‐tPh) and DEHA at contents of 5–10 wt % increases the tensile storage modulus (E' ) of PC owing to the antiplasticization effect. In particular, p‐tPh increases E' more than the other additives, suggesting that the rod‐like shape matches the free volume of PC in the glassy state. The three tPh isomers improve the glassy birefringence of PC while DEHA does not change the glassy birefringence, which corresponds to the polarizability anisotropy. The stress‐optical coefficient, a ratio of stress and birefringence, of PC decreases with increasing additive content in order of p‐tPh ? o‐tPh > m‐tPh = DEHA. This result is agreement with a restricted rotational motion of additive molecule in PC, which is observed in dynamic mechanical and birefringence data. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55 , 1837–1842  相似文献   
139.
140.
The supersymmetry algebra is examined for the (2+1)-dimensional supersymmetric CPN?1 model, on the basis of the observation of Witten and Olive in (1+1) and (3+1) dimensions. We then demonstrate that also in this (2+1)-dimensional model the usual supersymmetry algebra is modified by the appearance of the topological numbers of the solitons, which are nothing but the instantons in (1+1) dimensions, as central charges. To obtain the model, we begin by constructing the supersymmetric model in (3+1) dimensions. Then it is reduced to (2+1) dimensions by means of the dimensional reduction technique. We observe that the (2+1)-dimensional supersymmetric CPN?1 model thus obtained admits an O(2) extended supersymmetry.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号