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   117篇
  免费   4篇
  国内免费   5篇
化学   99篇
晶体学   5篇
力学   5篇
综合类   1篇
数学   8篇
物理学   8篇
  2022年   5篇
  2020年   3篇
  2019年   3篇
  2018年   4篇
  2017年   2篇
  2016年   3篇
  2015年   4篇
  2014年   3篇
  2013年   4篇
  2012年   6篇
  2011年   3篇
  2010年   3篇
  2008年   2篇
  2007年   3篇
  2006年   3篇
  2005年   3篇
  2004年   1篇
  2003年   3篇
  2002年   6篇
  2001年   1篇
  2000年   1篇
  1999年   2篇
  1998年   2篇
  1995年   1篇
  1994年   4篇
  1993年   3篇
  1992年   3篇
  1991年   3篇
  1990年   3篇
  1989年   8篇
  1988年   2篇
  1987年   7篇
  1986年   4篇
  1985年   3篇
  1984年   3篇
  1983年   2篇
  1981年   1篇
  1978年   1篇
  1976年   1篇
  1973年   1篇
  1969年   1篇
  1967年   1篇
  1966年   3篇
  1965年   1篇
排序方式: 共有126条查询结果,搜索用时 15 毫秒
11.
Crystals of 1-amino 2-phenyl benzocycloheptanol hydrobromide monohydrate are orthorhombic witha=6·927(17),b=30·947(40),c=30·990(40) Å,z=16 and the space group is Iba2.ρ=1·41 gm/ccρ cal=1·403 gm/cc,μ for CuKα=37.06 cm?1. The structure was solved by heavy atom method using three dimensional x-ray intensity data and refined by block diagonal and full matrix least squares method to anR-index of 0·106. The structure is stabilised by a number of hydrogen bonds of the type N-H…O, O-H…Br, N-H…Br. The heptane rings in this molecule are in chair conformation.  相似文献   
12.
In view of developing novel bioactive compounds, a series of 2‐(5‐[2‐methyl‐6‐arylpyridin‐3‐yl]‐1,3,4‐oxadiazol‐2‐ylthio)‐1‐arylethanones (6a–n) were designed and synthesized in good yield. Novel compounds were evaluated for their antibacterial and anti‐inflammatory activities. All synthesized compounds were screened for their antibacterial activity against Staphylococcus aureus, Bascillus subtilis, Eschericia coli, and Pseudomonas aeruginosa strains. Compounds 6a , 6b , 6c , 6h , and 6i displayed the highest antibacterial activity with minimal inhibitory concentration (MIC) values ranging from 6.25–12.5 μg/mL in comparison with the standard Ciprofloxacin. The results of anti‐inflammatory activity of carrageenan‐induced footpad edema assay indicated that tested compounds exhibited remarkable anti‐inflammatory activity with percentage of inhibition of 63.9–70.1% (potency 96.8–106.20% of indomethacin activity) after 3 hr. Particularly, 6c – e and 6j – l were found to be excellent inhibitors of inflammation, with potential higher than that of the standard, Indomethacin.  相似文献   
13.
His‐tagged molecular species, a ferrocene derivative and Protein A, were immobilized on electrode surfaces (Au and graphite) through formation of a chelated complex in the presence of Cu2+ cations used as bridging units. The complex was cleaved and the attached molecules were released from the electrode surface by applying reductive potential to the electrodes resulting in Cu2+ reduction, thus decomposing the chelate complex. The molecule release process was followed by cyclic voltammetry in case of the ferrocene derivative. His‐tagged Protein A was additionally labeled with a fluorescent tag and its release was followed by fluorescence measurements in the solution and by impedance spectroscopy at the electrode. The studied release of the His‐tagged redox species and biomolecules was considered as a new generic approach to the signal‐controlled molecule release applicable in various biotechnological and biomedical applications.  相似文献   
14.
(I)Lantadene-B: C35H52O5,M r =552.80, MonoclinicC2,a=25.65(1),b=6.819(9),c=18.75(1) Å,=100.61(9),V=3223(5) Å3,Z=4,D x =1.14 g cm–3 CuK (=1.5418A),=5.5 cm–1,F(000)=1208,R=0.118,wR=0.132 for 1527 observed reflections withF o 2(F o ). (II)Lantadene-C: C35H54O5·CH3OH,Mr=586.85, Monoclinic,P21,a=9.822(3),b=10.909(3),c=16.120(8)Å,=99.82(4),V=1702(1)Å3,Z=2,D x =1.145 g cm–3, MoK (=0.7107Å), =0.708 cm–1 F(000)=644,R=0.098, wR=0.094 for 1073 observed reflections. The rings A, B, C, D, and E aretrans, trans, trans, cis fused and are in chair, chair, sofa, half-chair, chair conformations, respectively, in both the structures. In the unit cell the molecules are stabilized by O-HO hydrogen bonds in both the structures, however an additional C-HO interaction is observed in the case of Lantadene-C.DCB Contribution No 809.  相似文献   
15.
16.
The first total synthesis of a bioactive metabolite, isolated from the fungi Acremonium sp. HKI 0230, containing a cyclopentaspirobenzofuran carbon framework, employing an Ireland ester Claisen rearrangement and RCM reaction based strategy has been accomplished.  相似文献   
17.
18.
N-m-tolyl phthalimide, C15NO2H11 crystallizes in the space group Cc with unit cell dimensions,a=8·54(1),b=19·89(2),c = 7·59(1)A, β=114·53(1)° andZ=4.V=1173(2)A3,D m =1·35(1),D c = 1·344 mg.m−3,M r =237 λCoKa=1·7903A. The structure was solved byMULTAN and refined to an R-factor of 0·116 for 632 counter reflections. The molecules are held together by van der Waal’s forces. The angle between the tolyl plane and the plane through the phthalimide group is 53·4(4)°. Contribution No. 607.  相似文献   
19.
A sensitive, rapid, and simple spectrophotometric method is described for the determination of sulfa drugs. The method is based on the formation of a red-colored product by the diazotization of sulfonamides such as sulfathiazole (SFT), sulfadiazine (SFD), sulfacetamide (SFA), sulfamethoxazole (SFMx), sulfamerazine (SFMr), sulfaguanidine (SFG), and sulfamethazine (SFMt), followed by complexation with dopamine in the presence of molybdate ions in (1 + 1) H2SO4 medium. Absorbance of the resulting red product is measured at 490-510 nm, and the product is stable for 2 days at 27 degrees C. Beer's law is obeyed in the concentration range of 0.04-8.0 microg/mL at the wavelength of maximum absorption. The method was used successfully for the determination of some sulfonamides in tablets and eye drops. Common excipients used as additives in pharmaceuticals do not interfere in the proposed method. The method offers the advantages of simplicity, rapidity, and sensitivity without the need for extraction or heating. The limits of detection and quantitation were calculated for SFT, SFD, SFA, SFMx, SFMr, SFG, and SFMt.  相似文献   
20.
The Nickel (II) complexes [Ni(Cl)2(metf)(o-phen)] (1), [Ni(Cl)2(metf)(opda)] (2) , [Ni(Cl)2(metf)(en)] (3) , [Ni(Cl)2(metf)(2,2'-bipy)] (4) , (metf = metformin, o-phen = ortho-phenanthroline, opda = ortho-phenylenediamine, en = ethylenediamine, 2–2′ bipy = 2–2′ bipyridyl) were synthesized and characterized using LC–MS, elemental analysis, molar conductance measurements, TGA-DTA, IR spectroscopy, magnetic moment measurements and electronic spectroscopy. The central Ni2+ was found to be in octahedral geometry. The DNA interaction of these complexes have been studied by UV–visible absorption studies, fluorescence emission technique and viscosity measurement. The complexes showed absorption hyperchromism in UV–visible spectra with calf thymus DNA. The binding constants from UV–visible absorption studies were 7.42 × 104, 0.74 × 104, 3.19 × 104, 5.9 × 104 M−1 for 1 , 2 , 3 and 4 , respectively and Stern-Volmer quenching constants from fluorescence studies were 0.16, 0.41, 0.23, 0.18, respectively. Viscosity measurements revealed that the binding of the complexes with DNA could be surface binding, mainly due to groove binding. The highest DNA cleavage activity of the complexes is recorded for complex 1 . The complexes were docked in to B-DNA sequence, 5′(D*AP*CP*CP*GP*AP*CP* GP*TP*CP*GP*GP*T)-3′ retrieved from protein data bank (PDB ID: 423D), using Discovery Studio 2.1 software. C Docker Intectraction energy of 1 , 2 , 3 and 4 complexes is 32.027, 31.427, 35.393 and 30.521 respectively. The highest docking score is seen for complex 3 .  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