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   349篇
  免费   12篇
化学   255篇
晶体学   5篇
力学   7篇
数学   31篇
物理学   63篇
  2023年   8篇
  2022年   10篇
  2021年   9篇
  2020年   12篇
  2019年   9篇
  2018年   10篇
  2017年   18篇
  2016年   17篇
  2015年   6篇
  2014年   12篇
  2013年   27篇
  2012年   37篇
  2011年   27篇
  2010年   18篇
  2009年   15篇
  2008年   19篇
  2007年   9篇
  2006年   8篇
  2005年   10篇
  2004年   13篇
  2003年   8篇
  2002年   7篇
  2001年   5篇
  2000年   2篇
  1999年   1篇
  1998年   2篇
  1995年   1篇
  1994年   1篇
  1993年   3篇
  1992年   5篇
  1990年   2篇
  1989年   1篇
  1987年   2篇
  1986年   1篇
  1985年   4篇
  1984年   1篇
  1983年   2篇
  1982年   1篇
  1981年   2篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1973年   4篇
  1972年   2篇
  1971年   1篇
  1970年   1篇
  1969年   3篇
  1966年   1篇
  1962年   1篇
排序方式: 共有361条查询结果,搜索用时 15 毫秒
71.
The binding behavior of triphenylene based copper ensemble prepared in situ has been investigated toward various anions (F(-), Cl(-), Br(-), I(-), CH(3)COO(-), H(2)PO(4)(-), NO(3)(-), OH(-), ClO(4)(-), CN(-), CO(3)(-) and SO(4)(-)) by UV-vis and fluorescence spectroscopy. Among various anions tested, 1-Cu(2+) ensemble shows selective and sensitive response towards cyanide ions and responds to CN(-) ions even in the presence of bovine serum albumin and in blood serum milieu. Further, as practical application of compound 1, we utilized the TLC strips coated with THF solution of 1 for the solid state detection of copper and cyanide ions.  相似文献   
72.
A thiacalix[4]arene based fluorescent chemosensor 3 in the cone conformation has been synthesized and its recognition behaviour is evaluated toward various metal ions in mixed aqueous media. The chemosensor 3 showed high selectivity towards Fe(3+) ions by fluorescence quenching of excimer emission. Further, evaluation of the 3·Fe(3+) complex prepared in situ demonstrated great promise for the detection of the Fe(3+) ion in the presence of amino acids, blood serum and bovine serum albumin (BSA) solution. The compound 3 has suitable permeability into the PC3 cells and can be utilized as a Fe(3+) selective sensor in living cells (PC3 cells).  相似文献   
73.
Bioflavonoids are plant compounds touted for their potential to treat or prevent several diseases including cancer caused by various stress conditions. Galangin (4H-1-Benzopyran-4-one, 3, 5, 7-trihydroxy-2-phenyl-), a flavonoid, is a polyphenolic compound found primarily in medicinal herb, Alpinia galanga. This study aims to demonstrate the galangin as a pharmacological lead compound using in vitro, in vivo, and in silico model targeting specific cancer condition and proteins. The proliferation of MCF-7 and Ehrlich ascites carcinoma (EAC) cells was significantly inhibited with an IC50 of 34.11 and 22.29???g/ml, respectively. In an animal model system, galangin has inhibited the tumor growth by 73.51%?±?4.742 in EAC-induced Swiss Albino mice with no evidences of mortality as compared to standard drug, 5-fluorouracil. The effectiveness of galangin is proven in an animal system suggesting its pharmacokinetics behavior in an animal model which is also complemented by outcome of in silico analysis with more than 88?% of human intestinal absorption and significant Caco-2 cell, MDCK cell, and skin permeability as predicted by in silico methods. Galangin was docked against 19 different proteins involved in tumorogenesis and apoptosis; the energetic analysis indicates that it exhibits higher predicted binding free energy of ?12.7?kcal/mol with Bcl-xL protein.  相似文献   
74.
The concerted interplay between reactive nuclear and electronic motions in molecules actuates chemistry. Here, we demonstrate that out-of-plane torsional deformation and vibrational excitation of stretching motions in the electronic ground state modulate the charge-density distribution in a donor-bridge-acceptor molecule in solution. The vibrationally-induced change, visualised by transient absorption spectroscopy with a mid-infrared pump and a visible probe, is mechanistically resolved by ab initio molecular dynamics simulations. Mapping the potential energy landscape attributes the observed charge-coupled coherent nuclear motions to the population of the initial segment of a double-bond isomerization channel, also seen in biological molecules. Our results illustrate the pivotal role of pre-twisted molecular geometries in enhancing the transfer of vibrational energy to specific molecular modes, prior to thermal redistribution. This motivates the search for synthetic strategies towards achieving potentially new infrared-mediated chemistry.

Channelling vibrational excitation energy to achieve ground-state charge-transfer (CT)-assisted isomerization in a donor-bridge-acceptor molecule in solution.  相似文献   
75.
76.
A series of copper (II) ( 1 and 3 ) and cobalt (II/III) ( 2 , 4 and 5 ) complexes comprising different imino‐phenolate ligands DCH , DTH and DBH 2 (where DCH = 2,4‐dichloro‐6‐((mesitylimino)methyl)phenol, DTH = 2,4‐di‐tert‐butyl‐6‐((mesitylimino)methyl) phenol and DBH 2 = 2,4‐dibromo‐6‐((mesitylimino)methyl)phenol) have been prepared with excellent yield and high purity. By utilizing different spectroscopic tools such as UV–visible, electrospray ionization (ESI)‐mass, Fourier‐transform infrared (FTIR) spectrometry and elemental analysis, the prepared complexes ( 1 – 5 ) were thoroughly characterized. The molecular structure of the synthesized complexes was ascertained by using single‐crystal X‐ray diffraction studies (SCXRDs). The experiment reveals that Complexes 1 – 5 bind to calf thymus DNA (CT‐DNA) through non‐intercalative way with good interacting abilities. However, 1 – 5 are excellent quenchers of the fluorescence intensity of bovine serum albumin (BSA) following the static pathway. Additionally, they had shown remarkable cytotoxic potential against MCF‐7 (mammary gland adenocarcinoma) and A549 (lung adenocarcinoma) cell lines. The IC50 values associated with these complexes were much lower than the conventional drug cisplatin. Apoptosis‐induced cell death was confirmed from the DNA fragmentation studies and Hoechst 33342 staining. The 2′,7′‐dichlorofluorescein diacetate (DCFDA) assay indicates that the complex mediated reactive oxygen species (ROS) generation is accountable for governing the apoptosis mechanism via oxidative cell distress. Apart from these studies, by carrying out density functional theory (DFT) method, highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) energy gap calculations and optimized structures of the synthesized complexes were accomplished.  相似文献   
77.
A new concept called “configurational temperature” is introduced in the context of dusty plasma, where the temperature of the dust particles submerged in the plasma can be measured directly from the positional information of the individual dust particles and the interaction potential between the dust grains. This method does not require the velocity information of individual particles, which is a key parameter to measure the dust temperature in the conventional method. The technique is initially tested using two-dimensional (2D) OpenMP parallel molecular dynamics and Monte Carlo simulation and then compared with the temperature evaluated from experimental data. The experiment have been carried out in the Dusty Plasma Experimental (DPEx) device, where a 2D stationary plasma crystal of melamine formaldehyde particles is formed in the cathode sheath of a DC glow discharge argon plasma. The kinetic temperature of the dust is calculated using the standard particle image velocimetry technique at different pressures. An extended simulation result for the three-dimensional case is also presented, which can be employed for the temperature measurement of a three-dimensional dust crystal in laboratory devices.  相似文献   
78.
79.
The intermittency effect has been observed in interactions of 800 GeV protons with emulsion-nuclei in one-(pseudorapidity/azimuthal angle) and two-dimensional (pseudorapidity and azimuthal angle) phase spaces in different multiplicity intervals. The intermittency strength is found to decrease with increasing multiplicity. Compared to one dimension, the two dimensional distribution is found to reflect better the intermittent behavior of the interactions. The dependence of various intermittency parameters on order of moment gives clear evidence of self-similar cascade mechanism in the interactions but there is no definite indication of the presence of different phases in the cascade.  相似文献   
80.
A novel dipyrromethane based receptor has been synthesized. It works as a highly selective colorimetric sensor for F? and Cu2+ ions, which can be used for their necked eye detection with evident colour change of its solution.  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