全文获取类型
收费全文 | 479篇 |
免费 | 13篇 |
专业分类
化学 | 227篇 |
晶体学 | 9篇 |
力学 | 32篇 |
数学 | 45篇 |
物理学 | 179篇 |
出版年
2022年 | 3篇 |
2020年 | 6篇 |
2019年 | 10篇 |
2017年 | 16篇 |
2016年 | 11篇 |
2015年 | 4篇 |
2014年 | 18篇 |
2013年 | 48篇 |
2012年 | 15篇 |
2011年 | 17篇 |
2010年 | 20篇 |
2009年 | 16篇 |
2008年 | 22篇 |
2007年 | 18篇 |
2006年 | 10篇 |
2005年 | 17篇 |
2004年 | 4篇 |
2003年 | 12篇 |
2002年 | 11篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1997年 | 4篇 |
1996年 | 9篇 |
1995年 | 13篇 |
1994年 | 6篇 |
1993年 | 13篇 |
1992年 | 7篇 |
1991年 | 13篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1988年 | 10篇 |
1986年 | 13篇 |
1985年 | 7篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 6篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 4篇 |
1969年 | 4篇 |
1967年 | 4篇 |
1959年 | 2篇 |
排序方式: 共有492条查询结果,搜索用时 31 毫秒
101.
Summary An X-ray fluorescence method is described for the determination of Sm, Eu, Tb, Dy, Ho, Yb and Y in gadolinium oxide. Samples are taken in oxalate form and mixed with boric acid in the ratio 31. The mixture is pressed as a double-layer pellet. Selection of experimental parameters and choice of analysis lines is discussed. The estimation limit ranges from 0.005–1% for most of the elements.
Röntgenfluorescenz-spektrometrische Bestimmung von Sm, Eu, Tb, Dy, Ho, Yb und Y in hochreinem Gadoliniumoxid
Zusammenfassung Bei dem vorgeschlagenen Verfahren werden die Proben in die Oxalatform übergeführt und mit Borsäure im Verhältnis 31 gemischt. Die Mischung wird zu einer Doppelschicht-Tablette gepreßt. Die Auswahl der geeigneten experimentellen Parameter sowie der Analysenlinien wird diskutiert. Die Bestimmungs-grenzen liegen für die meisten Elemente im Bereich 0,005–1%.相似文献
102.
103.
M. S. Ramakrishna P. K. Dhal D. D. Deshpande G. N. Babu 《Journal of polymer science. Part A, Polymer chemistry》1986,24(9):2107-2117
Radiation-induced copolymerization of hydrophili+ monomers, viz., 2-hydroxyethyl methacrylate (HEMA), 2-hydroxypropyl methacrylate (HPMA), and N-vinyl-2-pyrrolidone (NVP) with vinyl acetate (VAc) was carried out in bulk at 25°C. The copolymer composition was determined from the acetoxy content. The copolymerization parameters were determined by a graphical method and compared with those determined by the Yezrielev, Brokhina, and Roskin (YBR) method. Thermal properties of copolymers were studied by GC-MS. Probable mechanisms were suggested from the products obtained. 相似文献
104.
A. B. Deshpande R. V. Subramanian S. L. Kapur 《Journal of polymer science. Part A, Polymer chemistry》1967,5(4):761-767
Polymerization of isoprene in presence of a heterogeneous Ziegler-type catalyst system, Cr(AcAc)3–AlEt3, has been studied in benzene medium. The rate of polymerization is first-order with respect to catalyst as well as monomer concentration. The rate studies, activation energy, and polymer microstructures are reported in order to follow the probable mechanism of polymerization. 相似文献
105.
A. B. Deshpande C. R. Rajan S. L. Kapur 《Journal of polymer science. Part A, Polymer chemistry》1973,11(6):1317-1320
Vanadium-based catalyst complexes prepared in the presence of monomers have been used for the copolymerization of styrene and acrylonitrile. VOCl3–Al(i-C4H9)3 catalyst system seems to yield an alternating copolymer. The copolymers are easily soluble in DMF and have low softening points. 相似文献
106.
Chemoselective hydrogenation of substituted nitroaromatics using novel water-soluble iron complex catalysts 总被引:2,自引:0,他引:2
Deshpande RM Mahajan AN Diwakar MM Ozarde PS Chaudhari RV 《The Journal of organic chemistry》2004,69(14):4835-4838
Chemoselective hydrogenation of substituted nitroaromatic compounds by water-soluble iron complex catalysts with molecular hydrogen has been reported for the first time. This biphasic catalyst presents an opportunity for a solvent-free hydrogenation. This catalyst system provides a low-cost, efficient alternative to the selective but environmentally unacceptable stoichiometric reductions as well as the supported noble metal catalysts used for hydrogenation. An efficient recycling strategy has resulted in a cumulative turnover number above 6000. 相似文献
107.
108.
A. B. Deshpande S. M. Kale S. L. Kapur 《Journal of polymer science. Part A, Polymer chemistry》1973,11(9):2105-2109
Styrene is polymerized with chromium acetylacetonate–triisobutylaluminum catalyst at 40°C in a benzene medium. At the stoichiometric ratio of Al/Cr of 4, the activity for polymerization was found to be maximum. Further, the kinetic studies were carried out at this ratio of Al/Cr of maximum activity. The kinetics of polymerization and the total activation energy around 10.00 kcal/mole suggest a coordinate anionic mechanism. 相似文献
109.
A study of theEXAFS associated with theK x-ray absorption discontinuity of germanium in pure germanium and in the rare-earth germanides RGe2 (where R=La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er and Y) has been carried out. The Ge-Ge distances have been obtained in these
compounds. Considering the phase to the RGe2 system, the bond lengths in these compounds have been determined. The values obtained by us for the RGe2 compounds (R=La, Ce, Pr, Nd, Sm, Gd, Dy and Y) agree with those obtained earlier by crystallographic methods. The bond lengths
for the compounds TbGe2, HoGe2 and ErGe2 are also being reported. 相似文献
110.