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   288篇
  免费   3篇
化学   229篇
晶体学   3篇
力学   4篇
数学   11篇
物理学   44篇
  2023年   3篇
  2022年   6篇
  2021年   12篇
  2020年   8篇
  2019年   16篇
  2018年   20篇
  2017年   9篇
  2016年   11篇
  2015年   7篇
  2014年   11篇
  2013年   17篇
  2012年   13篇
  2011年   19篇
  2010年   11篇
  2009年   9篇
  2008年   12篇
  2007年   14篇
  2006年   7篇
  2005年   6篇
  2004年   6篇
  2003年   10篇
  2002年   4篇
  2001年   6篇
  2000年   6篇
  1997年   2篇
  1996年   2篇
  1995年   3篇
  1994年   2篇
  1990年   1篇
  1988年   2篇
  1987年   2篇
  1986年   2篇
  1985年   2篇
  1984年   2篇
  1983年   3篇
  1982年   2篇
  1979年   1篇
  1978年   4篇
  1976年   1篇
  1975年   4篇
  1974年   1篇
  1973年   3篇
  1972年   3篇
  1971年   1篇
  1970年   1篇
  1968年   1篇
  1967年   1篇
  1966年   2篇
排序方式: 共有291条查询结果,搜索用时 15 毫秒
131.
Journal of Optimization Theory and Applications - Many convex optimization problems have structured objective functions written as a sum of functions with different oracle types (e.g., full...  相似文献   
132.
Presently available methods for the determination of hydrogen in the gas phase are analyzed. Various procedures for the detection of hydrogen both at pre-explosion and at very low (less than 50 ppm) concentrations by means of thermocatalytic, semiconductor, amperometric, and potentiometric electrochemical sensors are considered.  相似文献   
133.
134.
Photodynamic and photothermal therapies (PDT, and PTT, respectively) are promising candidates for multimodal anticancer therapies (i.e., combinations of therapies), since their action is based on mechanisms that generally cannot be resisted by cancer cells, that is, generation of highly oxidizing oxygen species and high temperature, respectively. Herein, hybrid materials that combine octahedral molybdenum clusters as potential PDT agents and plasmonic spherical gold nanoparticles (AuNPs) as PTT agents are reported. Partial overlap of the photoemission spectrum of the cluster and the surface plasmon resonance band of the AuNPs facilitates energy transfer between the photoactive components, which resulted in synergetic enhancement of their photophysical properties. Specifically, by careful selection of the spacing between the cluster and the gold nanoparticle, a significant increase in luminescence and photosensitizing properties of the cluster was achieved in comparison with similar, but gold-free, particles. On the other hand, the cluster complex facilitated energy conversion to heat by gold particles and hence increased the heating rate under laser irradiation.  相似文献   
135.
The effective use of photochromic systems based on azo compounds in a number of applications, especially biomedical and pharmacological ones, is impeded by the unresolved problem of their EZ isomerization in the near-IR region, NIR (780–1400 nm). We have demonstrated at the TD-DFT, STEOM-DLPNO-CCSD and CASSCF-NEVPT2 levels of theory that the presence of a silylated diazene core −Si−N=N−Si− with three-, tetra- or five-coordinated silicon atoms practically guarantees the absorption of the E and Z forms of such derivatives in NIR and the amazing (185–400 nm) separation of their first absorption bands. In particular, the maximum λ1 of the first n→π* band of the E isomer of azosilabenzene ASiB is at ∼1030 nm, while for the Z isomer λ1≅1340 nm. Based on the found bistable azo compounds ( ASiB , bis(silyl)- SiD and bis(silatranyl)- SaD diazenes) and their derivatives with E and Z absorption in NIR, unique photoswitches can be created for a number of applications, in particular, for photothermal therapy.  相似文献   
136.
In a search of nitric oxide synthase inhibitors with prolonged vasoconstrictive activity, a series of lipophilic cyclohexafused 2-amino-2-thiazolines was obtained via cyclization of tert-butyl- or benzoyl-substituted N-(cyclohex-2-en-1-yl)thioureas. The crystal structure of intermediate N-[(3aRS,7aSR)- 3a,4,5,6,7,7a-hexahydro-1,3-benzothiazol-2-yl]benzamide hydrobromide was determined by X-ray analysis. One compound was found to cause pronounced and prolonged vasoconstrictive effect after single injection to the Wystar rats with lipopolysaccharide induced acute endotoxic (vasodilatation) shock.  相似文献   
137.
Highly stable unsymmetrical donor–acceptor oligothiophenes equipped with terminal electron-donating triphenylamine and an electron-withdrawing phenyldicyanovinyl groups have been synthesized. An influence of the length of conjugated oligothiophene π-spacer between the donor and acceptor blocks on solubility, thermal, optical and electrochemical properties of such compounds has been revealed.  相似文献   
138.
Russian Journal of Organic Chemistry - Functionally substituted oxiranes were synthesized by epoxidation of unsaturated compounds of the adamantane series with m-chloroperoxybenzoic acid....  相似文献   
139.
The thermal decomposition of the chelate Cd(n-BuOCS2)2 (I) in EtOH and DMF, either in the absence or in the presence of Ph3P, yields finely disperse CdS particles. Mixed-ligand complex Cd(Ph3P)(n-BuOCS2)2 (II) has been synthesized. Cd(Ph3P)(n-BuOCS2)2 · Ph3P (III) single crystals have been grown. By X-ray crystallography, the crystal structure of III is built of [Cd(Ph3P)(n-BuOCS2)2] mononuclear complex molecules and uncoordinated Ph3P molecules, which reside inside channels formed by complex II molecules. The coordination polyhedron around a Cd atom is a tetragonal pyramid where the base is formed by the four S atoms of the two bidentate chelating ligands n-BuOCS2 and the P atom of the Ph3P ligand is at the axial vertex. In the structure of III, there are supramolecular assemblies of two complex II molecules.  相似文献   
140.
The cuprates La2 ? x Sr1 + x Cu2O6 + δ(x = 0, 0.1, 0.2) are synthesized by solid-state method. Their dc conductivity was studied over the 373 to 1173 K temperature range and 10 to 2.1 × 104 Pa oxygen partial pressure range by using four-probe technique. It is shown that the cuprate conductivity in air is maximal at ~673 K; it is 60 S/cm for La2SrCu2O6.09; 68 S/cm, for La1.9Sr1.1Cu2O6.18; and 81 S/cm, for La1.8Sr1.2Cu2O6.10. The thermal expansion coefficient of La2SrCu2O6.09 is determined by thermomechanical method and high-temperature X-ray diffraction method; its value (16 ppm K?1) shows that the material is compatible with the ceria-based solid electrolytes during the thermal cycling.  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