全文获取类型
收费全文 | 338篇 |
免费 | 7篇 |
专业分类
化学 | 216篇 |
晶体学 | 4篇 |
力学 | 9篇 |
数学 | 7篇 |
物理学 | 109篇 |
出版年
2021年 | 2篇 |
2019年 | 2篇 |
2017年 | 5篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 11篇 |
2013年 | 52篇 |
2012年 | 7篇 |
2011年 | 11篇 |
2010年 | 8篇 |
2009年 | 12篇 |
2008年 | 8篇 |
2007年 | 10篇 |
2006年 | 11篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 12篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 2篇 |
1989年 | 7篇 |
1988年 | 10篇 |
1987年 | 11篇 |
1986年 | 10篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1979年 | 7篇 |
1978年 | 9篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 8篇 |
1974年 | 5篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1958年 | 3篇 |
1937年 | 1篇 |
1931年 | 2篇 |
排序方式: 共有345条查询结果,搜索用时 15 毫秒
111.
R. Hamatsu S. Kitamura T. Yamagata M. Bogdanski E. Jeannet A.M. Cooper S.N. Ganguli A. Gurtu P.K. Malhotra U. Mehtani R. Raghavan A. Subramanian T. Emura I. Kita K. Takahashi H. Kohno L. Montanet 《Nuclear Physics B》1978,137(3):283-293
annihilations with ? 3 prongs with an incident antineutron momentum between 0.5 and 0.8 GeV/c are analysed. We present the topological branching ratios and cross sections, the resonance production rates and possible ?-ω interference effects. 相似文献
112.
S. L. Malhotra A. B. Deshpande S. L. Kapur 《Journal of polymer science. Part A, Polymer chemistry》1968,6(1):193-203
The polymerization of styrene with two catalyst systems consisting of Al(C2H5)3 in combination with ZrCl4 or ZrCl3 has been studied. The rate of polymerization with catalyst concentration was first-order with ZrCl4 system and second-order with ZrCl3 system, but at higher catalyst concentrations in both cases, the rate progressively decreases and finally attains a low value. The rate of polymerization is, however, proportional to the square of the monomer concentration in both the cases. The overall energy of activation was 10.9 kcal./mole and 6.45 kcal./mole in these systems. The polymers obtained with ZrCl4 were of lower molecular weights as compared to those obtained with ZrCl3. The polymers in both the cases had amorphous character. 相似文献
113.
The electron paramagnetic resonance (EPR) of Nd2(SO4)3 · 8H2O and Sm2(SO4)3 · 8H2O doped with Gd3+ has been carried out at 273 K and the spin-Hamiltonian parameters are deduced. The zero field splittings have been computed and compared with those observed directly by Bogle and Symmons. It is found that the discrepancy in the zero field splittings. between computed and directly observed values falls within the range of linewidths of directly observed values. 相似文献
114.
L. P. Blanchard G. G. Gabra S. L. Malhotra 《Journal of polymer science. Part A, Polymer chemistry》1975,13(7):1619-1643
The copolymerization of propylene oxide (PO) with tetrahydrofuran (THF) in dichloroethane (DCE) has been studied at ?10, 0, +10, and +20°C. The reactions were initiated by triphenylmethyl cations associated with the following gegenions: PF6?, SbF6?, and AsF6?. The overall energies of activation (Eα of PO and Ea of THF) obtained with the three gegenions increase as one passes from PF6? to AsF6? then to SbF6?, though the magnitude of the increase in each case is not substantial. On the other hand, the associated frequency factors A show a considerable variation with the gegenion. The bimodal distributions of the molecular weights, obtained by GPC with the copolymer produced from reactions initiated with triphenylmethyl hexafluorophosphate, show that the proportions of the lower molecular weight component (L) decrease as the solvent is changed from DCE to toluene, and this is even more marked when bulk polymerization conditions are adopted. The proportions of the higher molecular weight component (H) however increase, as does its molecular weight. The GPC molecular weight distributions of the copolymers initiated with triphenylmethyl hexafluorophosphate in DCE to which water has been added, show that the molecular weight of component H decreases with increasing concentration of water, while that of component L remains practically unchanged at a value of 308. This corresponds to an average degree of polymerization (DP ) of 4 to 5. The NMR and infrared spectra of copolymers prepared in the presence of still higher initial water concentrations indicate that the PO-based polymer segments are present in excess of those required for a 1:1 copolymer. 相似文献
115.
J. Bartke H. Kirk J. Kaltwasser J. Klabuhn K. Böckmann G. Zobernig H. Bohr M.J. Counihan P.K. Malhotra D.R.O. Morrison H. Saarikko K. Śliwa T.C. Bacon P.J. Dornan F. Mandl M. Markytan M. Bardadin-Otwinowska A. Wroblewski 《Nuclear Physics B》1977,118(5):360-370
The production of η(550) and ω(780) mesons is studied in π±p interactions at 16 GeV/c and K?p interactions at 10 and 16 GeV/c. Cross sections for exclusive channels are presented, and for the π+p data differential cross sections are given for quasi-inclusive production where the η or ω is required to be accompanied by charged particles only. Close similarities are observed between η, ω and also ?0(770) production in terms of longitudinal and transverse variables. By a rough estimate, the η, ω and ?0 inclusive yields are found to be in the ratio 0.32 : 0.85 : 1, respectively, for 16 GeV/cπ+p collisions. For non-peripheral production we estimate this same ratio to be 0.34 : 0.9 : 1. 相似文献
116.
117.
R. Nacasch Ch. Defoix L. Dobrzynski P.Ladron de Guevara R. Raghavan M. Aguilar-Benitez J. Diaz A. Ferrando E. Gil J.A. Rubio F. Barreiro A. Gurtu L. Montanet A.M. Cooper S.N. Ganguli P.K. Malhotra A. Subramanian 《Nuclear Physics B》1978,135(2):203-223
In this paper we have investigated the properties of the D(1285) and E(1420) meson resonances using the five-body annihilation channels obtained in a large statistics experiment (28 events/μb). The analysis favours the 1+ spin-parity assignment for the D(1285) meson. The dominant decay mode of the D(1285) into is found to be δ(970)π. The situation concerning the E(1420) meson remains confused although not inconsistent with previous analyses. Partial cross sections on resonance production are also presented. 相似文献
118.
Lifetimes of high spin states up to {
}=22+ in the yrast positive parity bands have been measured to investigate the shape evolution with increasing spin in 72, 74Se. The Q
t values derived from these measurements indicate that prolate shape stabilizes for 72Se, while a triaxial shape develops for 74Se at higher spins. Comparison of the observed trend in Q
t with spin for 72, 74Se with that of the corresponding kryptones isotones emphasizes the stability provided by N=38 prolate shell gap even at high rotational frequency. 相似文献
119.
Amitabh Jha Sanjay Malhotra Virinder S. Parmar William Errington 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(7):899-900
The title compound, 2,2‐dimethylchroman‐6‐ol, C11H14O2, has been identified as a side product from the condensation of hydroquinone with 2‐methylbut‐3‐en‐2‐ol. The pyran ring has a half‐chair conformation. The hydroxyl groups are involved in intermolecular hydrogen bonding which generates infinite spiral chains around the fourfold screw axes; the O?O hydrogen‐bonded distances are 2.661 (1) Å. 相似文献
120.
Sarangal Himali Thapar Simrandeep Singh Nisar Kottakkaran Sooppy Singh Manjit Malhotra Jyoteesh 《Optical and Quantum Electronics》2021,53(10):1-14
Optical and Quantum Electronics - A D-shape elliptical stoma photonic crystal fiber (PCF) based on surface plasmon resonance is proposed and investigated with finite element method. The gold film... 相似文献