全文获取类型
收费全文 | 427篇 |
免费 | 8篇 |
专业分类
化学 | 268篇 |
晶体学 | 9篇 |
力学 | 9篇 |
数学 | 40篇 |
物理学 | 109篇 |
出版年
2022年 | 5篇 |
2019年 | 6篇 |
2018年 | 3篇 |
2017年 | 7篇 |
2016年 | 3篇 |
2015年 | 7篇 |
2014年 | 14篇 |
2013年 | 17篇 |
2012年 | 22篇 |
2011年 | 12篇 |
2010年 | 12篇 |
2009年 | 10篇 |
2008年 | 16篇 |
2007年 | 12篇 |
2006年 | 12篇 |
2005年 | 19篇 |
2004年 | 14篇 |
2003年 | 16篇 |
2002年 | 17篇 |
2001年 | 9篇 |
2000年 | 10篇 |
1999年 | 7篇 |
1997年 | 4篇 |
1996年 | 11篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 7篇 |
1992年 | 9篇 |
1991年 | 6篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 9篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 6篇 |
1978年 | 8篇 |
1977年 | 11篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1974年 | 4篇 |
1973年 | 6篇 |
1972年 | 5篇 |
1969年 | 3篇 |
1965年 | 2篇 |
1962年 | 2篇 |
排序方式: 共有435条查询结果,搜索用时 171 毫秒
51.
Kirti Patel Sudhir Kapoor D. P. Dave Tulsi Mukherjee 《Journal of Chemical Sciences》2005,117(1):53-60
Silver nanosized crystallites have been synthesized in aqueous and polyols viz., ethylene glycol and glycerol, using a microwave
technique. Dispersions of colloidal silver have been prepared by the reduction of silver nitrate both in the presence and
absence of stabilizer poly(vinylpyrolidone) (PVP). It was observed that PVP is capable of complexing and stabilizing Ag nanoparticles
formed through the reduction of Ag+ ions in water and ethylene glycol. In the case of ethylene glycol, it has been shown that the use of PVP leads to particles
with a high degree of stability. The colloids are stable in glycerol for months even in the absence of stabilizer. 相似文献
52.
Photophysical characteristics of capped and uncapped CdS particles have been investigated in aqueous solution. It is seen
that the fluorescence spectrum shifts towards lower energies in the presence of toluene dithiol (TDT) and dimercaptophthalic
acid (DMPA). This shift, which is due to quenching of shallow traps, is more predominant with TDT. Also, the presence of excess
Cd2+ ions at the surface of the CdS particles facilitates the binding of dithiolenes. 相似文献
53.
S. Kapoor C. Gopinathan R. M. Iyer 《Journal of Radioanalytical and Nuclear Chemistry》1988,125(1):91-96
Mixtures of methanol and isopropanol in a ratio (v/v) varying from 91 to 19 have been gamma-irradiated at 77 K and relative yields of trapped electrons have been measured. The reactivity of the trapped electrons towards acetone and uranyl nitrate has been studied at various methanol isopropanol ratios. On the basis of the results, an attempt has been made to assess the relative importance of the reaction of the electron with the solute prior to trapping with respect to the tunnelling reaction of the trapped electron with the solute. 相似文献
54.
S.C.L. Sharma G.K. Mehta R.K. Choudhury D.M. Nadkarni S.S. Kapoor 《Nuclear Physics A》1981,355(1):13-24
The emission probabilities per fission of α-particles, tritons and protons have been measured in fast neutron induced fission of 235U. The measurements were carried out at neutron energies of 120, 180, 230 and 550 keV. AΔE-E semiconductor detector telescope was used to identify different light charged particles and the fission fragments were detected with an ionization chamber. The three-parameter data corresponding to the pulse heights from the ΔE-E detectors and the ion-chamber were recorded event by event on magnetic tape and were analyzed off-line by computer. No significant variation in the most probable energy () and the standard deviation (σE) of the energy spectra of different light charged particles with incident neutron energy was observed, although was seen to have a slightly higher value beyond En = 230 keV. The yield of α-particles in fission induced by neutrons of En ~ 200 keV was found to be higher by about 20 % than that in thermal neutron induced fission. The yields of tritons and protons were found to increase significantly with neutron energy. 相似文献
55.
Berger's technique of neglecting the second strain invariant in the middle plane of the plate is used in an investigation of the effect of non-linearity on the frequency of a vibrating circular plate of variable thickness which is elastically restrained along its circumference. A simple polynomial expression for the deflection function and a Galerkin method are used in the analysis. 相似文献
56.
Anudeep K. Narula Beer Singh Sandhya Gupta Ramesh N. Kapoor 《Transition Metal Chemistry》1984,9(10):379-382
Summary Niobium(V) and tantalum(V) pentaethoxides react with monofunctional benzoyl hydrazones (BHy) in refluxing benzene to give products of the type, M(OEt)5–n(BHy)n (where M=Nb or Ta and n=1, 2 or 3). The complexes have been characterised on the basis of elemental analysis, spectral (i.r. and n.m.r.) and molecular weight data. 相似文献
57.
Using a 40 cm curved mica crystal spectrograph of the transmission type, the L spectrum of gadolinium has been investigated. The forbidden transition LIINII at λ = 1618.9 X.U. has been reported for the first time. 相似文献
58.
Studies of prompt radiations emitted in fission were started at Trombay in the late 1950’s by Dr R Ramanna and over the years
extensive investigations on the emission of prompt neutrons, gamma ray and K x-rays in fission were carried out with neutron
beams fromapsara andcirus reactors. In the early 1960’s studies on the emission of light-charged particles in fission, which is a rare mode of fission,
were also started. This paper reviews some of the recent studies on the emission of light-charged particles (lcp) in fission which were carried out with a view to investigate the mechanism oflcp emission, the scission configuration and the dynamics of the last stages of the fission process. 相似文献
59.
Ramesh Chander Kapoor 《Pramana》1976,7(5):334-343
Gravitational recoil of a gigantic black hole (M∼108–9 M⊙) formed in the nonspherical collapse of the nuclear part of a typical galaxy can take place with an appreciable speed as
a consequence of the anisotropic emission of gravitational radiation. Accretion of gaseous matter during its flight through
the galaxy results in the formation of a glowing shock front. The accompanying stellar captures can lead to the formation
of an accretion disk-star system about the hole. Consequently, the hole can become “luminous” enough to be observable after
it emerges out of the galaxy. The phenomenon seems to have an importance in relation to the observations of quasar-galaxy
association in a number of cases. 相似文献
60.
A study of optogalvanic (OG) signals in a uranium hollow cathode discharge using a tunable pulsed dye laser with intensities above saturation revealed certain systematic trends. The peaks of OG signals, for a given hollow cathode current, due to all transitions involving the ground state are within a certain range of values. The same is true of the OG signals due to transitions involving the 620 cm-1 and 3800 cm-1 lower metastable levels. For all transitions involving the same lower state, the peaks of OG signal vary linearly with the discharge current. The slopes of such straight lines are different for transitions involving different lower levels of uranium. Effects of radiation trapping are seen in the OG signals due to transitions involving the ground state of uranium at currents above 60 mA. Details of our observations are presented and discussed. 相似文献