首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   170篇
  免费   5篇
化学   85篇
数学   9篇
物理学   81篇
  2016年   3篇
  2015年   3篇
  2013年   4篇
  2012年   3篇
  2011年   3篇
  2010年   8篇
  2008年   7篇
  2007年   6篇
  2006年   2篇
  2005年   9篇
  2004年   2篇
  2002年   6篇
  2000年   2篇
  1995年   2篇
  1994年   2篇
  1992年   3篇
  1991年   5篇
  1989年   3篇
  1988年   3篇
  1987年   2篇
  1985年   2篇
  1984年   3篇
  1983年   4篇
  1982年   2篇
  1981年   3篇
  1978年   6篇
  1977年   4篇
  1976年   3篇
  1975年   5篇
  1974年   5篇
  1973年   4篇
  1971年   5篇
  1970年   4篇
  1969年   4篇
  1968年   3篇
  1967年   8篇
  1966年   1篇
  1965年   1篇
  1964年   2篇
  1940年   1篇
  1937年   2篇
  1936年   3篇
  1935年   1篇
  1934年   1篇
  1933年   2篇
  1932年   2篇
  1929年   3篇
  1928年   1篇
  1927年   1篇
  1920年   2篇
排序方式: 共有175条查询结果,搜索用时 859 毫秒
101.
102.
High-spin states in85Kr have been studied via in-beam spectroscopy by bombarding a82Se target with 32 MeV7Li ions. Since85Kr is only formed with a small relative cross section proton-— coincidence techniques have been applied to enhance the rays of85Kr, even with respect to those of86Kr, in the measurements. A new sequence of high-spin states with excitation energies up to 4.8 MeV and tentative spins up to (23/2) has been established on top of the 17/2+ s isomer. A tentative assignment of the configurationvg 9 2/–1 (g 9/2 p 3 2/–1 orf 5 2/–1 ) to the new levels is proposed.Supported by Deutsche Forschungsgemeinschaft  相似文献   
103.
Using methods of in-beam spectroscopy in connection with 35 MeV7Li bombardment of82Se targets four new isomers have been identified. They are observed in83Br at 3070 keV (T1/2=0.6±0.2 μs), in85Rb at 2826 keV (T1/2=12.5±0.6 ns), in85Kr at 1991 keV (T1/2=1.2+ 0.4 1.0 μs) and in86Kr at 2250 keV (T1/2=3.1±0.6 ns). Spin and parity 19/2? have been assigned to the new isomer in85Rb that is interpreted as the coupling of a p3/2 proton to the g 9 2/?2 two-neutron excitation of the N=48 neutron system. Using the TDPAD method an upper limit for the g-factor of ¦g¦≦0.17 has been estimated for this isomer. The same two-neutron excitation is also believed to be responsible for the new isomer in83Br. The new isomers in85Kr and86Kr are interpreted as configurations containing the two-proton excitation (f 5 2/?1 , p 3 2/?1 ) where in the isomeric 17/2+ level of85Kr an additional g9/2 neutron hole is involved.  相似文献   
104.
The determination of metals in cubic ferrites is performed by volumetric analysis in the semi-microscale. The iron content is titrated cerimetrically. All other elements are determined by complexometric titration, partially after separation by ion-exchange methods. The separation of iron was achieved by ether and cupferron extraction. The errors of the determination amount up to 0.5% for iron, for other metals up to 1.0% or about 2% in the case of multicomponent systems.  相似文献   
105.
Summary. This article deals with inequality measures on income distributions. These measures are assumed to fulfil common axioms like the Principle of Progressive Transfers, Normalization, and Symmetry. Strict Monotonicity will be defined and is included in the basic set of axioms. If the measures are especially based on bilateral comparisons and if two additional conditions are fulfilled the bilateral inequality measure must be proportional to the absolute distance of the two incomes involved. It is remarkable that all these conditions do not give an answer whether an inequality measure for two incomes should be a quasi-convex or a quasi-concave function. This question is controversely discussed in economic research. Our surprising answer, however, is given by use of RAO's statistic concept defining the diversity of a population.  相似文献   
106.
The interaction of phenyl‐substituted indolo[3,2‐b]quinolines with DNA G‐quadruplexes of different topology were studied by using a combination of spectroscopic and calorimetric methodologies. N5‐Methylated indoloquinoline derivatives (MePIQ) with an aminoalkyl side chain exhibit high affinities for the parallel‐stranded MYC quadruplex and a (3+1)‐hybrid structure combined with an excellent discrimination against the antiparallel thrombin‐binding aptamer (TBA) and the human telomeric (HT) quadruplexes. Dissociation constants for the binding of the ligand to the MYC quadruplex are in the submicromolar range, being below the corresponding dissociation constants for the antiparallel‐stranded quadruplexes by about one order of magnitude. Competition experiments with double‐helical DNA reveal the impact of indoloquinoline structural features on the selectivity for the parallel quadruplex relative to duplex DNA. Based on a calorimetric analysis binding to MYC is shown to be equally driven by favorable enthalpic and entropic contributions with no significant impact on the type of cation present.  相似文献   
107.
108.
We present in this paper the Generic RAdiative traNsfer AnD non-LTE population Algorithm (GRANADA). This model is able to compute non-LTE populations for vibrational, rotational, spin (i.e., NO and OH), and electronic (i.e., O2) states in a given planetary atmosphere. The model is very flexible and can be used for computing very accurate non-LTE populations or for calculating reasonably accurate but at high speed non-LTE populations in order to implement it into non-LTE remote sensing retrievals. We describe the model in detail and present an update of the non-LTE collisional processes and their rate coefficients for the most important molecules in Earth's atmosphere. In addition, we have applied the model to the most important atmospheric infrared emitters including 13 species (H2O, CO2, O3, N2O, CO, CH4, O2, NO, NO2, HNO3, OH, N2, and HCN) and 460 excited vibrational or electronic energy levels. Non-LTE populations for all these energy levels have been calculated for 48 reference atmospheres expanding from the surface up to 200 km, including seasonal (January, April, July and October), latitudinal (75°S, 45°S, 10°S, 10°N, 45°N, 75°N) and diurnal (day and night) coverages. The effects of the most recent updates of the non-LTE collisional parameters on the non-LTE populations are briefly described. This climatology is available online to the community and it can be used for estimating non-LTE effects at specific conditions and for testing and validation studies.  相似文献   
109.
Differential cross sections as a function of cm angle were measured for 1n- and 2n-transfer reactions in 238U + 197 Au and197 Au + 197 Au collisions in the energy range from 0.881 Vc to 1.093 Vc and 0.825 Vc to 0.964 Vc, respectively. For 198Au and 199Au from the 238U + 197Au collisions, for reduced distances of closest approach d o 1.55 fm, the angular distributions at all bombarding energies are well described by the semiclassical theory. Equivalently, the transfer probabilities show the expected exponential decrease with increasing d o over many orders of magnitude. For all other transfer products from 238U + 197Au collisions, and for all transfer products from 197Au + 197Au collisions, markedly reduced cross sections relative to the semiclassical theory are observed for central collisions at all bombarding energies, even for values of d o that are well outside the region where absorption is known to set in. Only for the more peripheral collisions, one observes agreement of the angular distributions (transfer probabilities) with the semiclassical expectations. The deviations for central collisions are absent for reactions with positive Q gg values and scale roughly with increasingly negative values of Q gg, i.e. with increasing Q-value mismatch. Channel coupling is proposed as the relevant mechanism.  相似文献   
110.
Ohne ZusammenfassungAn dieser Stelle möchte ich meinem hochverehrten Lehrer, Herrn Prof. Dr. Alois Zinke, für die Förderung und das Interesse, das er meinen Arbeiten entgegenbringt, den herzlichsten Dank aussprechen.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号