全文获取类型
收费全文 | 170篇 |
免费 | 0篇 |
国内免费 | 3篇 |
专业分类
化学 | 79篇 |
力学 | 10篇 |
数学 | 53篇 |
物理学 | 31篇 |
出版年
2019年 | 2篇 |
2018年 | 2篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 13篇 |
2012年 | 7篇 |
2011年 | 8篇 |
2010年 | 5篇 |
2009年 | 6篇 |
2008年 | 5篇 |
2007年 | 5篇 |
2006年 | 7篇 |
2005年 | 6篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1944年 | 2篇 |
1943年 | 4篇 |
1940年 | 1篇 |
1939年 | 2篇 |
1933年 | 1篇 |
排序方式: 共有173条查询结果,搜索用时 31 毫秒
41.
The new [(Zr6B)Cl11-xI2+x] phase (with 0 < or = x < or = 6) is obtained from reactions of ZrI4, ZrCl4, and elemental Zr and B for 2-4 weeks in sealed Ta tubing at 800-850 degrees C. Single crystals of [(Zr6B)Cl6.44(7)I6.56] have been characterized by X-ray diffraction at room temperature (orthorhombic Pbcn, Z = 4, a = 12.365(2) A, b = 15.485(3) A, c = 13.405(2) A). This structure contains zigzag chains of boron-centered (Zr6B) octahedra that are interconnected by Cl(i-i) halides. Further three-dimensional connectivity is achieved by I(a-a-a) bridges. The noncluster interconnecting two-bonded X(i) sites are occupied statistically by a mixture of Cl and I. For each site both positions were resolved. This structure forms within a phase width of 0 < or = x < or = 6 at temperatures between 800 and 850 degrees C. Crystals of this phase appear to be always multiply twinned. 相似文献
42.
P A Stadler S Guttmann H Hauth R L Huguenin E Sandrin G Wersin H Willems A Hofmann 《Helvetica chimica acta》1969,52(6):1549-1564
The syntheses of the alkaloids of the ergotoxine-group i.e. ergocristine, α- and β-ergokryptine, and ergocornine, are described. Using starting material with known stereochemistry these syntheses allowed to determine the absolute configurations also at C-2′ and C-12′ in the peptide part, which could not be derived from analytical data. All ergot alkaloids of the peptide type possess the same stereochemical structure. 相似文献
43.
44.
Alexej Michailovski JohannesB. Willems Norbert Stock GretaR. Patzke 《Helvetica chimica acta》2005,88(9):2479-2501
Within the frame of systematic morphological studies concerning the solvothermal formation of nanoscale and microscale molybdenum oxides from the interaction of a molybdenum‐based precursor such as MoO3⋅2 H2O with ionic additives such as alkali and earth alkali halides, we studied – with the aim to elaborate preparative guidelines – the influence of the precursor structure and the alkali halide upon the crystal structure of the emerging alkali polymolybdates in terms of solvothermal fields and high‐throughput solvothermal techniques. The discussion of the resulting crystal structures revealed a structure‐directing potential of the alkali cations that was explored for the synthesis of new mixed alkali polymolybdates. 相似文献
45.
A. H. Jay W. W. Stevenson E. W. Colbeck S. W. Craven W. Murray N. T. Wilkinson W. J. Agnew R. Treje C. Benedicks G. A. Medwedewa W. P. Remin F. Willems J. J. Berzelius Ed. Houdremont P. Klinger G. Blaschczyk P. Klineer und W. Koch 《Fresenius' Journal of Analytical Chemistry》1944,127(1):43-46
Ohne Zusammenfassung 相似文献
46.
47.
We developed and fabricated an all-fiber add-drop filter by recording a Bragg grating in the waist of an asymmetric mode converter-coupler formed by adiabatic tapering and fusing of two locally dissimilar, single-mode optical fibers. The insertion loss of the device was ~0.1 dB .A narrow spectral bandwidth (<1 nm) and a large add-drop efficiency (>90%) were also demonstrated. In addition, the filter was polarization independent. 相似文献
48.
The Dembowski semi-planes are the semi-planes which were determined by P. Dembowski [3]. A Dembowski semi-i-space (i1) is an incidence structure J=(P,B,I) for which: (i) each element of B is incident with at least i+3 elements of P, and (ii) each i-residual space of J is a Dembowski semi-plane. The article [5] contained the complete classification of all Dembowski semi-1-spaces, in this article we classify all Dembowski semi-2-spaces. 相似文献
49.
Willems AV Deforce DL Van den Eeckhout EG Lambert WE Van Peteghem CH De Leenheer AP Van Bocxlaer JF 《Electrophoresis》2002,23(24):4092-4103
Benzo[a]pyrene diol epoxide (BPDE) was reacted in vitro with (2'-deoxy)nucleotides and with calf thymus DNA. The modified DNA was enzymatically hydrolyzed to the 5'-monophosphate nucleotides using deoxyribonuclease I (DNA-ase I), nuclease P1 and snake venom phosphodiesterase (SVP). Most of the unmodified nucleotides were removed using solid phase extraction (SPE) in a polystyrene divinylbenzene copolymer. Three adducts could be detected and identified using capillary zone electrophoresis(negative)-ion electrospray ionization-mass spectrometry (CZE-(-)-ESI-MS) in conjunction with sample stacking. This way, not only a BPDE-dGMP adduct [(M-H)(-) at m/z 648], a well-known nucleotide adduct, could be retrieved, but also a BPDE-dAMP [(M-H)(-) at m/z 632] and a BPDE-dCMP adduct [(M-H)(-) at m/z 608] could be detected for the first time. The presence of the prominent ion at m/z 195 (the deoxyribose-phosphate ion) in the three low-energy collision-activated decomposition (CAD) spectra indicated that the adducts were formed through base-alkylation. CZE-positive ion ESI-MS/MS experiments were performed to obtain further information on base-alkylation. The absence of the loss of NH(3) from the nucleobase in each CAD spectrum points to an alkylated exocyclic NH(2) position of the nucleobase. So, the three adducts could be identified as BPDE-N(2)-dGMP, BPDE-N(6)-dAMP and BPDE-N(4)-dCMP using CZE-ESI-MS and CZE-ESI-MS/MS. 相似文献
50.
G. Thanheiser E. Brauns G. Maaßen A. Eder H. J. van Royen H. Grewe F. Willems P. Klinger W. Koch H. H. Geist G. C. Chandlee A. Raab B. P. Selenetzky I. Musatti G. Ziliani J. Gapanowitsch F. P. Peters J. H. Yoe R. T. Hall W. M. Peschkowa A. D. Jegorow L. Kebrich L. Kulberg P. L. Kirk und G. T. Bentley 《Fresenius' Journal of Analytical Chemistry》1939,117(5-6):205-212
Ohne Zusammenfassung 相似文献