全文获取类型
收费全文 | 311篇 |
免费 | 8篇 |
专业分类
化学 | 197篇 |
晶体学 | 1篇 |
力学 | 16篇 |
数学 | 13篇 |
物理学 | 92篇 |
出版年
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 4篇 |
2020年 | 7篇 |
2019年 | 13篇 |
2018年 | 11篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 8篇 |
2014年 | 12篇 |
2013年 | 25篇 |
2012年 | 20篇 |
2011年 | 14篇 |
2010年 | 8篇 |
2009年 | 14篇 |
2008年 | 14篇 |
2007年 | 16篇 |
2006年 | 12篇 |
2005年 | 8篇 |
2004年 | 10篇 |
2003年 | 12篇 |
2002年 | 12篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1975年 | 1篇 |
1973年 | 2篇 |
1963年 | 2篇 |
排序方式: 共有319条查询结果,搜索用时 15 毫秒
71.
F. Brandolini M. De Poli P. Pavan R.V. Ribas D. Bazzacco C.R. Rossi-Alvarez 《The European Physical Journal A - Hadrons and Nuclei》1999,6(2):149-155
The g-factors of some members of the ground state band and of the 2+ state in the %-vibrational band have been measured in 160,162,164Dy using the Coulomb Excitation Transient Field technique, induced by 58Ni projectiles at 230, 210 and 217 MeV, respectively. The g-factors in the ground state band are consistent with a constant value, while that of the 2+% states is about 20% larger in average than those in the ground state band. Results are discussed in the frame of the systematics in this nuclear region. 相似文献
72.
73.
Magnetic properties of glucose coated cuprous oxide nanoparticles of different sizes have been studied. Unlike bulk Cu2O, which shows diamagnetic behavior, the nanoparticles show superparamagnetic behavior. A superparamagnetic blocking temperature of 21 K is observed for 5 nm particles. A magnetic hysteresis loop with a coercivity of 406 Oe is observed for these particles at 5 K. The magnetization and the coercivity increase with decreasing particle size. The superparamagnetic behavior, along with the increase in magnetization and coercivity with decreasing particle size, is due to the enhanced surface contributions to the magnetism. 相似文献
74.
D. L. Balabanski M. Ionescu-Bujor A. Iordachescu D. Bazzacco F. Brandolini D. Bucurescu S. Chmel M. Danchev M. De Poli G. Georgiev H. Haas H. Hübel N. Marginean R. Menegazzo G. Neyens P. Pavan G. Rainovski C. Rossi Alvarez C. A. Ur K. Vyvey S. Frauendorf 《The European Physical Journal A - Hadrons and Nuclei》2003,20(1):191-192
The quadrupole interaction of high-spin isomers in 193Pb implanted into solid Hg cooled at a temperature T = 170 K has been investigated by the time-differential perturbed
-ray angular-distribution method. Spectroscopic quadrupole moment values of
eb and 0.45(4) eb have been deduced for the 21/2- and 33/2 + three-neutron states, respectively. A much higher value
eb has been determined for the 29/2- isomer, the band head of a magnetic rotational band.Received: 4 November 2002, Published online: 2 March 2004PACS:
21.10.Ky Electromagnetic moments - 27.80. + w
相似文献
75.
Pavan G Hayward TJ Borsani JF Priano M Manghi M Fossati C Gordon J 《The Journal of the Acoustical Society of America》2000,107(6):3487-3495
A distinctive vocalization of the sperm whale, Physeter macrocephalus (=P. catodon), is the coda: a short click sequence with a distinctive stereotyped time pattern [Watkins and Schevill, J. Acoust. Soc. Am. 62, 1485-1490 (1977)]. Coda repertoires have been found to vary both geographically and with group affiliation [Weilgart and Whitehead, Behav. Ecol. Sociobiol. 40, 277-285 (1997)]. In this work, the click timings and repetition patterns of sperm whale codas recorded in the Mediterranean Sea are characterized statistically, and the context in which the codas occurred are also taken into consideration. A total of 138 codas were recorded in the central Mediterranean in the years 1985-1996 by several research groups using a number of different detection instruments, including stationary and towed hydrophones, sonobuoys and passive sonars. Nearly all (134) of the recorded codas share the same "3+1" (/// /) click pattern. Coda durations ranged from 456 to 1280 ms, with an average duration of 908 ms and a standard deviation of 176 ms. Most of the codas (a total of 117) belonged to 20 coda series. Each series was produced by an individual, in most cases by a mature male in a small group, and consisted of between 2 and 16 codas, emitted in one or more "bursts" of 1 to 13 codas spaced fairly regularly in time. The mean number of codas in a burst was 3.46, and the standard deviation was 2.65. The time interval ratios within a coda are parameterized by the coda duration and by the first two interclick intervals normalized by coda duration. These three parameters remained highly stable within each coda series, with coefficients of variation within the series averaging less than 5%. The interval ratios varied somewhat across the data sets, but were highly stable over 8 of the 11 data sets, which span 11 years and widely dispersed geographic locations. Somewhat different interval ratios were observed in the other three data sets; in one of these data sets, the variant codas were produced by a young whale. Two sets of presumed sperm whale codas recorded in 1996 had 5- and 6-click patterns; the observation of these new patterns suggests that sperm whale codas in the Mediterranean may have more variations than previously believed. 相似文献
76.
Roberto Todeschini Viviana Consonni Andrea Mauri Manuela Pavan 《Analytica chimica acta》2004,515(1):199-208
Regression models with good fitting but no predictive ability are sometimes chance correlations and often show some pathological features such as multicollinearity, overfitting, and inclusion of noisy/spurious variables. This problem is well known and of the utmost importance. The present paper proposes some criteria that are to be fulfilled as conditions for model acceptability, the aim being to recognize linear regression models with pathology. These criteria have been thought of in order to face the following problems:
- •
- model instability due to outliers and influential objects;
- •
- predictor multicollinearity;
- •
- redundancy in explanatory variables;
- •
- overfitting due to chance factors.
77.
G. de Angelis T. Martinez A. Gadea N. Marginean E. Farnea E. Maglione S. Lenzi W. Gelletly C.A. Ur D.R. Napoli Th. Kroell S. Lunardi B. Rubio M. Axiotis D. Bazzacco A.M. Bizzeti Sona P.G. Bizzeti P. Bednarczyk A. Bracco F. Brandolini F. Camera D. Curien M. De Poli O. Dorvaux J. Eberth H. Grawe R. Menegazzo G. Nardelli J. Nyberg P. Pavan B. Quintana C. Rossi Alvarez P. Spolaore T. Steinhart I. Stefanescu O. Thelen R. Venturelli 《The European Physical Journal A - Hadrons and Nuclei》2001,12(1):51-55
Gamma ray transitions de-exciting states in the N = Z nucleus 70Br have been identified for the first time using the GASP and EUROBALL arrays coupled with ancillary detectors. The level
scheme of 70Br has been established by means of particle-gated γ-γ and γ-γ-γ coincidences. The Coulomb energy differences between isobaric
analogue states in 70Br and 70Se show a deviation from the expected behaviour which could be related to dripline effects.
Received: 18 July 2001 / Accepted: 25 September 2001 相似文献
78.
A detailed study, on the static response of cross-ply laminated composite circular cylindrical shell of revolution and shell panel with various support conditions, has been made using Levy type of solution and the classical shell theories of FlSanders, Love and Donnell in an unified form. It has been shown that while developing a Levy type of solution using aforementioned theories, certain difficulty is encountered for determining the particular integral in respect of Fl Sanders and Love theories. This difficulty has been overcome by making use of the membrane solution as a particular integral. A comparative study has been carried out using the above shell theories for different geometrical parameters, lamination schemes and support conditions. It has been shown that Donnell theory predicts inaccurate results for certain lamination schemes, support conditions and geometrical parameters of the shell. It is suggested that, for developing shear deformation shell theories, it would be better to use a more accurate shell theory like Flügge Sommario. La risposta statica di gusci cilindrici circolari di materiale composito laminato, a strati incrociati, e di pannelli con varie condizioni di supporto viene analizzata utilizzando in una forma unificata soluzioni tipo Levy e le classiche teorie dei gusci di Flügge Sanders, Love e Donnell. Si mostra che nello sviluppare una soluzione di tipo Levy si incontra una certa difficoltà nel determinare l'integrale particolare rispetto alle teorie di Flügge, Sanders e Love. Tale difficoltà viene superata usando la soluzione di membrana come integrale particolare. Viene sviluppato uno studio comparativo facendo uso delle suddette teorie dei gusci per differenti parametri geometrici, schemi di laminazione e condizioni di vincolo. Si mostra che la teoria di Donnell fornisce risultati non accurati per certi schemi di laminazione, condizioni di supporto e parametri geometrici del guscio. Si suggerisce che per sviluppare teorie dei gusci che tengano conto delle deformazioni di scorrimento sarebbe più opportuno l'uso di una teoria dei gusci più accurata come ad esempio quella di Flügge. 相似文献
79.
Application of the Local Boundary Integral Equation Method to Boundary-Value Problems 总被引:5,自引:0,他引:5
A review of the meshless formulations based on local boundary integral equation (LBIE) methods is presented. Physical quantities are approximated by the moving least-squares method. A summary of recent developments in the application of the LBIE method to potential problems, elastostatics, elastodynamics, thermoelasticity, and plate bending problems is given. The efficiency and generality of the present formulation in a wide class of engineering problems are confirmed. 相似文献
80.
A new technique (to our knowledge), for the measurement of residual wedge angle (RWA) of high optical quality transparent nearly parallel plate (PP), using a quasi-monochromatic light source, is presented. Advantages and drawbacks of the technique and the results obtained for a PP, using a filtered white light source, is discussed. A slightly modified optical setup for accurate determination of RWA, using phase shifting interferometry (PSI), has been described. Results obtained, applying PSI, for a validation experiment and for the determination of RWA of a quasi-PP is presented. The PSI based technique does not suffer from any measurement ambiguities due to limitation in effective beam aperture. Hence the technique is suitable for high accuracy measurement of RWA of PP. In both the optical setups, presented in this paper, the respective interfering beams travel the same optical circuit and are thus subject to same perturbation in optical path, due to external mechanical vibration, which finally cancels out. Thus the measurements are much less affected by external vibrations. Since the respective interfering beams undergo identical reflections and transmissions, the visibility or contrast of the interference fringes is very good. 相似文献