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   1505篇
  免费   14篇
  国内免费   6篇
化学   1378篇
力学   1篇
数学   69篇
物理学   77篇
  2020年   6篇
  2018年   6篇
  2016年   13篇
  2015年   15篇
  2014年   14篇
  2013年   27篇
  2012年   28篇
  2011年   32篇
  2010年   15篇
  2009年   23篇
  2008年   20篇
  2007年   31篇
  2006年   22篇
  2005年   24篇
  2004年   17篇
  2003年   16篇
  2002年   16篇
  2001年   14篇
  2000年   14篇
  1999年   12篇
  1998年   7篇
  1997年   7篇
  1996年   14篇
  1995年   7篇
  1994年   8篇
  1993年   6篇
  1992年   15篇
  1991年   9篇
  1990年   19篇
  1989年   5篇
  1988年   10篇
  1986年   6篇
  1985年   13篇
  1983年   6篇
  1982年   9篇
  1981年   8篇
  1980年   8篇
  1979年   11篇
  1978年   10篇
  1977年   11篇
  1975年   5篇
  1971年   5篇
  1966年   76篇
  1965年   129篇
  1964年   143篇
  1963年   123篇
  1962年   125篇
  1961年   146篇
  1960年   124篇
  1959年   62篇
排序方式: 共有1525条查询结果,搜索用时 15 毫秒
91.
The difference between the singlet-singlet and the triplet-triplet absorption spectra of quinoline and isoquinoline has been measured from 45 000 to 15 000 cm?1, in a rigid hydrocarbon glass at 77 K, using a newly constructed computer controlled spectrograph. Both molecules show strong new triplet-triplet absorption bands in the ultraviolet region. Similar bands have recently been found in naphthalene and were assigned to transitions from the lowest triplet state to a triplet state which is doubly excited with respect to the closed shell ground state.  相似文献   
92.
We add an effective atom-centered nonlocal term to the exchange-correlation potential in order to cure the lack of London dispersion forces in standard density functional theory. Calibration of this long-range correction is performed using density functional perturbation theory and an arbitrary reference. Without any prior assignment of types and structures of molecular fragments, our corrected generalized gradient approximation density functional theory calculations yield correct equilibrium geometries and dissociation energies of argon-argon, benzene-benzene, graphite-graphite, and argon-benzene complexes.  相似文献   
93.
The enolic form of cyclic compounds like 4-hydroxycoumarin,-2-pyronones,-2-pyridones and cyclohexane-1,3-diones yields malonyl heterocycles by heating withMeldrum acid.Enolisierbare Ringverbindungen vom Typ des 4-Hydroxycumarins,-2-pyronons und-2-pyridons sowie des 1,3-Cyclohexandions schließen beim Erhitzen mitMeldrumsäure Ringe zu Malonyl-heterocyclen.

Herrn Prof. Dr.H. Nowotny gewidment.  相似文献   
94.
A classical result of G. Bouligand states that bounded harmonic functions can be extended across closed polar sets. F.-Y. Maeda replaced the boundedness assumption by the condition of energy finiteness for harmonic spaces with Green function.This paper proves this result for generalP-harmonic spaces and shows that the extension property for a harmonic functionu and the condition of energy finiteness are equivalent to a majorization property foru 2 .  相似文献   
95.
96.
A fewest switches trajectory surface hopping algorithm based on linear response time-dependent density-functional theory is developed and implemented into the plane wave ab initio molecular dynamics package CPMD. A scheme to calculate nonadiabatic couplings using a multi determinantal approximation of the excited state wave function is introduced. The method is applied to the study of the photorelaxation of protonated formaldimine, a minimal model of the rhodopsin chromophore retinal. A good agreement of the structural and dynamic behavior is found with respect to state averaged multiconfiguration self consistent field based trajectory surface hopping.  相似文献   
97.
Gold nanoparticles (AuNPs) are subjects of broad interest in scientific community due to their promising physicochemical properties. Herein we report the facile and controlled light‐mediated preparation of gold nanoparticles through a Norrish type I reaction of photoactive polymers. These carefully designed polymers act as reagents for the photochemical reduction of gold ions, as well as stabilizers for the in situ generated AuNPs. Manipulating the length and composition of the photoactive polymers allows for control of AuNP size. Nanoparticle diameter can be controlled from 1.5 nm to 9.6 nm.  相似文献   
98.
The Latin-American Network of Human Genetics (RELAGH) is an internet-based federation of human and medical genetic societies of Latin America constituted in 2001. Member societies include the Mexican Association of Human Genetics, the Brazilian Society of Clinical Genetics, the Human Genetics Section of the Argentinean Society of Genetics, the Colombian Society of Human Genetics and the Panamanian Human Genetics Society. RELAGH is a full member of the steering committee of the International Federation of Human Genetics Societies. A core activity of RELAGH is to become a platform for the integration and collaboration of human geneticists across Latin America regarding training, services and research in medical genetics in the region.  相似文献   
99.
Adlayers of different azobenzene-functionalized derivatives of the triazatriangulenium (TATA) platform on Au(111) surfaces were studied by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), gap-mode surface-enhanced Raman spectroscopy (gap-mode SERS), and cyclic voltammetry (CV). The chemical composition of the adlayers is in good agreement with the molecular structure, i.e., different chemical groups attached to the azobenzene functionality were identified. Furthermore, the presence of the azobenzene moieties in the adlayers was verified by the vibration spectra and electrochemical data. These results indicate that the molecules remain intact upon adsorption with the freestanding functional groups oriented perpendicularly to the TATA platform and thus also to the substrate surface.  相似文献   
100.
There is a growing recognition of the importance of protein kinases in the control of alternative splicing. To define the underlying regulatory mechanisms, highly selective inhibitors are needed. Here, we report the discovery and characterization of the dichloroindolyl enaminonitrile KH-CB19, a potent and highly specific inhibitor of the CDC2-like kinase isoforms 1 and 4 (CLK1/CLK4). Cocrystal structures of KH-CB19 with CLK1 and CLK3 revealed a non-ATP mimetic binding mode, conformational changes in helix αC and the phosphate binding loop and halogen bonding to the kinase hinge region. KH-CB19 effectively suppressed phosphorylation of SR (serine/arginine) proteins in cells, consistent with its expected mechanism of action. Chemical inhibition of CLK1/CLK4 generated a unique pattern of splicing factor dephosphorylation and had at low nM concentration a profound effect on splicing of the two tissue factor isoforms flTF (full-length TF) and asHTF (alternatively spliced human TF).  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