全文获取类型
收费全文 | 92篇 |
免费 | 2篇 |
专业分类
化学 | 69篇 |
晶体学 | 1篇 |
力学 | 2篇 |
数学 | 4篇 |
物理学 | 18篇 |
出版年
2022年 | 5篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 1篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 5篇 |
2012年 | 5篇 |
2011年 | 9篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 5篇 |
2007年 | 4篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2004年 | 5篇 |
2003年 | 4篇 |
2002年 | 6篇 |
2001年 | 1篇 |
1998年 | 1篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1975年 | 1篇 |
1968年 | 1篇 |
1934年 | 2篇 |
排序方式: 共有94条查询结果,搜索用时 234 毫秒
61.
Graft copolymerization of ethylmethacrylate (EMA) onto soy protein concentrate (SPC) was carried-out using ascorbic acid/potassium persulphate as redox initiator under microwave radiations. Different reaction parameters like reaction time, solvent amount, initiator ratio, pH and monomer concentration were optimized to get maximum graft yield (78.8%). The graft copolymer formed was characterized by FTIR, XRD, SEM, TGA, DTA and DTG techniques. Graft copolymer showed higher moisture resistance along with increased chemical and thermal stability. TGA, DTA and DTG studies could reveal the distinctive features of graft copolymerization of EMA onto S-S linkages of soy protein concentrate under the influence of microwave irradiations in addition to grafting at peptide linkages, which were further supported by FT-IR studies. 相似文献
62.
63.
Harbans L. Jindal Kiyoshi Matsuda Reita Tamamushi 《Journal of Electroanalytical Chemistry》1978,90(2):185-196
The electrochemical kinetic parameters for the polarographic reduction of Zn(II) at a dropping mercury electrode in concentrated supporting electrolytes consisting of sodium, ammonium, lithium, magnesium and calcium nitrates and sodium perchlorate have been determined at 25.0±0.1°C by the square-wave polarographic method. The rate parameter decreased with increase of radius of the alkali-metal cations present in the electrolyte and with increase of charge of the cation of the electrolyte in solution of the same ionic strength. It also decreases, passes through a minimum and then increases with the increase in the concentration of any of the supporting electrolytes. The initial decrease is ascribed to the Frumkin double-layer effect but the latter increase has been explained in terms of the change in the activity of water around the electrode. 相似文献
64.
Sunil Kumar Zinki Jindal Nitu Kumari Narendra Kumar Verma 《Journal of nanoparticle research》2011,13(10):5465-5471
To exploit the photoluminescent behavior of CdS at nanoscale with different doping concentration of europium—a rare earth
element, we report the synthesis of Eu-doped CdS nanorods by using low temperature solvothermal process by using ethylenediamine.
The outcomes can have future applications as phosphors, photovoltaic cells, lasers, light emitting diodes, bio-imaging, and
sensors. The doping was confirmed by electron dispersive spectroscopy supported by X-ray diffraction. From scanning electron
microscopy and transmission electron microscopy analysis it was observed that the average diameter of the Cd1−x
Eu
x
S nanorods is about 10–12 nm having lengths in the range of 50–100 nm. UV–Visible spectroscopy study was carried out to determine
the band gap of the nanorods and the absorbance peaks showed blue shift with respect to the bulk CdS. The blue shift was also
observed as the doping concentration of Eu increases. From photoluminescence (PL) studies at λex = 450 nm, peaks at 528 and 540 nm were observed due to CdS, peak at 570 nm is due to defects related transitions, while the
peak at 613 nm is due to Eu. As the doping concentration of Eu is increased the intensity of the luminescent peak at 613 nm
is increased. Thermogravimetric analysis showed the nanorods are thermally stable up to 300 °C. The traces of impurities adsorbed
on the nanorods were confirmed by Fourier transform infrared spectroscopy. 相似文献
65.
Lumata L Jindal AK Merritt ME Malloy CR Sherry AD Kovacs Z 《Journal of the American Chemical Society》2011,133(22):8673-8680
Hyperpolarized (89)Y complexes are attractive NMR spectroscopy and MR imaging probes due to the exceptionally long spin-lattice relaxation time (T(1) ≈ 10 min) of the (89)Y nucleus. However, in vivo imaging of (89)Y has not yet been realized because of the low NMR signal enhancement levels previously achieved for this ultra low-γ(n) nucleus. Here, we report liquid-state (89)Y NMR signal enhancements over 60,000 times the thermal signal at 298 K in a 9.4 T magnet, achieved after the dynamic nuclear polarization (DNP) of Y(III) complex of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) samples at 3.35 T and 1.4 K. The (89)Y DNP was shown to proceed by thermal mixing and the liquid state (89)Y NMR signal enhancement was maximized by (i) establishing the optimal microwave irradiation frequency, (ii) optimizing the glassing matrix, (iii) choosing a radical with negligible inhomogeneous line broadening contribution to the ESR linewidth, and (iv) addition of an electron T(1e) relaxation agent. The highest enhancements were achieved using a trityl OX063 radical combined with a gadolinium relaxation agent in water-glycerol matrix. Co-polarization of (89)YDOTA and sodium [1-(13)C]pyruvate showed that both (89)Y and (13)C nuclear species acquired the same spin temperature, consistent with thermal mixing theory of DNP. This methodology may be applicable for the optimization of DNP of other low-γ(n) nuclei. 相似文献
66.
67.
16‐[3‐Methoxy‐4‐(2‐piperidin‐1‐ylethoxy)benzylidene]‐17‐oxoandrost‐5‐en‐3β‐yl acetate monohydrate
S. Thamotharan V. Parthasarathi Ranju Gupta Sheetal Guleria D. P. Jindal Anthony Linden 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(12):o727-o729
The title compound, C36H49NO5·H2O, has the outer two six‐membered rings of the steroid nucleus in chair conformations. The central ring B of the steroid nucleus is in an 8β,9α‐half‐chair conformation, while ring D of the steroid adopts a slightly distorted 13β,14α‐half‐chair conformation. The piperidine ring is in a chair conformation. The methoxybenzylidene moiety has an E configuration with respect to the carbonyl group at position 17. Intermolecular O—H?O and O—H?N hydrogen bonds link the steroid and water molecules into chains which run parallel to the b axis. 相似文献
68.
Proton conducting oxide ceramics have shown potential for use in fuel cell technologies. Understanding the energy pathways for proton conduction could help us design more efficient fuel cell materials. This paper describes how octahedral tilting affects the relative energies of proton binding sites, transition states, and conduction pathways in cubic and pseudo-cubic perovskites. First, the structure for cubic and pseudo-cubic forms of BaTiO(3), BaZrO(3), CaTiO(3), and CaZrO(3), is found. Even when cubic symmetry is enforced, CaTiO(3), and CaZrO(3) exhibit octahedral tilting distortions characteristic of orthorhombic phases while BaTiO(3) and BaZrO(3) remain undistorted. Octahedral tilting gives rise to proton binding sites facilitating inter- and intra-octahedral proton transfer while the proton binding sites of undistorted perovskites facilitate only intra-octahedral proton transfer. The nudged elastic band method is used to find minimum energy paths between the proton binding sites. As distortions increase, inter-octahedral proton transfer barriers decrease while intra-octahedral proton transfer barriers increase. Concurrently, rotational barriers from oxygens facilitating inter-octahedral proton transfer increase while rotational barriers from oxygens facilitating intra-octahedral proton transfer decrease. Intra-octahedral transfer is the rate-limiting step to the lowest energy extended proton conduction pathway in all the perovskites considered. 相似文献
69.
70.
S. Thamotharan V. Parthasarathi P. Gupta D. P. Jindal P. Piplani Anthony Linden 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(8):o467-o469
The title compounds, 4‐(2‐naphthyloxymethylcarbonyl)morpholine, C16H17NO3, (I), and 4‐methyl‐1‐(2‐naphthyloxymethylcarbonyl)piperazine, C17H20N2O2, (II), are potential antiamnesics. The morpholine ring in (I) and the piperazine ring in (II) adopt chair conformations. In (I), the molecules are linked by weak intermolecular C—H⃛O interactions into chains that have a graph‐set motif of C(10), while in (II), the molecules are linked by weak intermolecular C—H⃛O interactions that generate two C(7) graph‐set motifs. The dihedral angle between the naphthalene moiety and the best plane through the morpholine ring is 20.62 (4)° in (I), while the naphthalene moiety is oriented nearly perpendicular to the mean plane of the piperazine ring in (II). 相似文献