全文获取类型
收费全文 | 239篇 |
免费 | 6篇 |
国内免费 | 2篇 |
专业分类
化学 | 124篇 |
晶体学 | 9篇 |
力学 | 18篇 |
数学 | 60篇 |
物理学 | 36篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 10篇 |
2019年 | 5篇 |
2018年 | 8篇 |
2017年 | 11篇 |
2016年 | 8篇 |
2015年 | 13篇 |
2014年 | 15篇 |
2013年 | 30篇 |
2012年 | 17篇 |
2011年 | 15篇 |
2010年 | 17篇 |
2009年 | 14篇 |
2008年 | 14篇 |
2007年 | 11篇 |
2006年 | 10篇 |
2005年 | 7篇 |
2004年 | 6篇 |
2003年 | 4篇 |
2002年 | 5篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1995年 | 1篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1975年 | 1篇 |
1973年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有247条查询结果,搜索用时 15 毫秒
241.
Abd El-Motaleb M. Ramadan Shaban Y. Shaban Mohammed M. Ibrahim Morad M. El-Hendawy Hatem Eissa Sami A. Al-Harbi 《中国化学会会志》2020,67(1):135-151
A template Schiff condensation of 2,6-pyridine dicarbaldehyde or 2,6-diformyl-4- bromophenol and 1,3–diamino-2-hydroxy propane or 3,4-diaminotoluene in the presence of copper(II) salts (CuX2) (X = Cl, Br, CH3COO, or ClO4) affords different types of copper(II) complexes. Depending on the employed molar ratio of the dicarbonyl compounds and diamines, different types of copper(II) complexes formed during the template condensation reaction. Structural formulation of the complexes was confirmed by elemental analysis (C, H, N, and M), physical measurements such as thermal analysis (TAG & DTG), molar conductivity, and magnetic moments in addition to spectral studies (UV–Vis, IR, and ESR). Homobinuclear in a four-coordinate square planar and five-coordinate square pyramidal and trigonal bipyramidal in monomeric structures are proposed. A mononuclear hexa-coordinate in an octahedral geometry is suggested as well. Oxidase biomimetic catalytic activity of these newly synthesized copper(II) complexes was examined toward the aerobic oxidation of 4-tert-butylcatechol (4-TBCH2) and o-aminophenol under catalytic conditions. Both catalytic and kinetic investigations demonstrate promising oxidase catalytic activity and based on the kinetic results, probable mechanistic catalytic implications are discussed. Geometrical structures of representative copper(II) complexes were determined by optimizing their bond lengths, bond angles, dihedral angles, and the structural index (τ). 相似文献
242.
Hatem Megdiche 《Journal of Mathematical Analysis and Applications》2011,374(1):323-330
In this paper we prove some compactness results for a large class of singular transport equations. Our approach relies on some comparison results for positive operators. Our results extend and complete several earlier works. We also provide simpler proofs for several known results in the literature. 相似文献
243.
Aboul-Fadl T Abdel-Aziz HA Abdel-Hamid MK Elsaman T Thanassi J Pucci MJ 《Molecules (Basel, Switzerland)》2011,16(9):7864-7879
In the present study a series of Schiff bases of indoline-2,3-dione were synthesized and investigated for their Mtb gyrase inhibitory activity. Promising inhibitory activity was demonstrated with some of these derivatives, which exhibited IC(50) values ranging from 50-157 mM. The orientation and the ligand-receptor interactions of such molecules within the Mtb DNA gyrase A subunit active site were investigated applying a multi-step docking protocol using Molecular Operating Environment (MOE) and Autodock4 docking software. The results revealed the importance of the isatin moiety and the connecting side chain for strong interactions with the enzyme active site. Among the tested compounds the terminal aromatic ring benzofuran showed the best activity. Promising new leads for developing a novel class of Mtb gyrase inhibitors were obtained from Schiff bases of indoline-2,3-dione. 相似文献
244.
Aboul-Fadl T Abdel-Aziz HA Kadi A Bari A Ahmad P Al-Samani T Ng SW 《Molecules (Basel, Switzerland)》2011,16(5):3544-3551
A facile and efficient method for synthesis of fenamic acid hydrazides from their acids in one-step reaction under microwave irradiation and solvent-free conditions was developed. Compared with the two-step conventional heating method, the process was simple, the reaction time was very short and the yields were almost quantitative. 相似文献
245.
Ultra high amorphous silicon passivation quality of crystalline silicon surface using in‐situ post‐deposition treatments 下载免费PDF全文
H. Meddeb Twan Bearda Wissem Dimassi Yaser Abdulraheem Hatem Ezzaouia Ivan Gordon Jozef Szlufcik Jef Poortmans 《固体物理学:研究快报》2015,9(1):53-56
A parametric study of post‐deposition hydrogen plasma treatment of intrinsic a:Si:H films is performed. We demonstrate a significant improvement in passivation of c‐Si(100) promoting epitaxy after an in‐situ hydrogen plasma treatment depending mainly on the pressure and slightly on the power. Plasma diagnostic indicates an increase of Hα* signal with high power and low pressure. However, our analysis reveals a better hydrogen incorporation with high pressure and a slight increase in monohydride with high power. Longer H2 plasma duration up to 50 s shows no detrimental effect on the passivation quality. Optimizing the in‐situ H2 plasma treatment, high minority carrier lifetime over 15 ms was achieved after short thermal annealing. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
246.
Hatem M. Titi Dr. Ranjan Patra Prof. Israel Goldberg 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(44):14941-14949
This study targets the construction of porphyrin assemblies directed by halogen bonds, by utilizing a series of purposely synthesized Sn(axial ligand)2–(5,10,15,20‐tetraarylporphyrin) [Sn(L)2‐TArP] complexes as building units. The porphyrin moiety and the axial ligands in these compounds contain different combinations of complimentary molecular recognition functions. The former bears p‐iodophenyl, p‐bromophenyl, 4′‐pyridyl, or 3′‐pyridyl substituents at the meso positions of the porphyrin ring. The latter comprises either a carboxylate or hydroxy anchor for attachment to the porphyrin‐inserted tin ion and a pyridyl‐, benzotriazole‐, or halophenyl‐type aromatic residue as the potential binding site. The various complexes were structurally analyzed by single‐crystal X‐ray diffraction, accompanied by computational modeling evaluations. Halogen‐bonding interactions between the lateral aryl substituents of one unit of the porphyrin complex and the axial ligands of neighboring moieties was successfully expressed in several of the resulting samples. Their occurrence is affected by structural (for example, specific geometry of the six‐coordinate complexes) and electronic effects (for example, charge densities and electrostatic potentials). The shortest intermolecular I???N halogen‐bonding distance of 2.991 Å was observed between iodophenyl (porphyrin) and benzotriazole (axial ligand) moieties. Manifestation of halogen bonds in these relatively bulky compounds without further activation of the halophenyl donor groups by electron‐withdrawing substituents is particularly remarkable. 相似文献
247.