全文获取类型
收费全文 | 435682篇 |
免费 | 5532篇 |
国内免费 | 1228篇 |
专业分类
化学 | 234047篇 |
晶体学 | 6489篇 |
力学 | 18767篇 |
综合类 | 13篇 |
数学 | 49935篇 |
物理学 | 133191篇 |
出版年
2021年 | 3768篇 |
2020年 | 4189篇 |
2019年 | 4523篇 |
2018年 | 5854篇 |
2017年 | 5744篇 |
2016年 | 8837篇 |
2015年 | 5565篇 |
2014年 | 8551篇 |
2013年 | 20192篇 |
2012年 | 15661篇 |
2011年 | 19277篇 |
2010年 | 13500篇 |
2009年 | 13356篇 |
2008年 | 17664篇 |
2007年 | 17559篇 |
2006年 | 16266篇 |
2005年 | 14558篇 |
2004年 | 13532篇 |
2003年 | 11902篇 |
2002年 | 11733篇 |
2001年 | 13442篇 |
2000年 | 10091篇 |
1999年 | 7920篇 |
1998年 | 6572篇 |
1997年 | 6315篇 |
1996年 | 6087篇 |
1995年 | 5476篇 |
1994年 | 5395篇 |
1993年 | 5200篇 |
1992年 | 5832篇 |
1991年 | 5929篇 |
1990年 | 5666篇 |
1989年 | 5474篇 |
1988年 | 5496篇 |
1987年 | 5383篇 |
1986年 | 5099篇 |
1985年 | 6567篇 |
1984年 | 6700篇 |
1983年 | 5305篇 |
1982年 | 5393篇 |
1981年 | 5371篇 |
1980年 | 4959篇 |
1979年 | 5353篇 |
1978年 | 5499篇 |
1977年 | 5389篇 |
1976年 | 5331篇 |
1975年 | 4917篇 |
1974年 | 4888篇 |
1973年 | 4883篇 |
1972年 | 3456篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
971.
Salimgareeva V. N. Polevoi R. M. Kolesov S. V. Ostakhov S. S. Ponomareva V. A. Leplyanin G. V. 《Russian Journal of Applied Chemistry》2003,76(5):804-808
The luminescence and scintillation properties of poly(methyl methacrylate) containing 1,1,3-trimethyl-3-phenylindan were studied. 相似文献
972.
M. I. Kurkin V. V. Leskovets V. V. Nikolaev E. A. Turov L. V. Turov 《Physics of the Solid State》2003,45(4):685-690
The possibility of excitation of NMR signals by an ac electric field in magnetically ordered crystals is discussed. Such signals can be recorded using the time-dependent component of the electric polarization vector. It is assumed that the electric and magnetic characteristics are coupled to each other through magnetoelectric and antiferroelectric interactions. Several types of magnetic structures are analyzed in which these interactions are not forbidden by symmetry. Such structures include two-sublattice single-position ferro-and antiferromagnetic phases in centrosymmetrical crystals, two-sublattice magnetic crystals without a center of symmetry (such as KNiPO4), and four-sublattice antiferromagnetic crystals with three types of antiferromagnetism vectors (such as Cr2O3 and α-Fe2O3). 相似文献
973.
974.
S. S. Andreev A. D. Akhsakhalyan M. A. Bibishkin N. I. Chkhalo S. V. Gaponov S. A. Gusev E. B. Kluenkov K. A. Prokhorov N. N. Salashchenko F. Schafers S. Yu. Zuev 《Central European Journal of Physics》2003,1(1):191-209
We present research investigations in the field of multilayer optics in X-ray and extreme ultra-violet ranges (XUV), aimed
at the development of optical elements for applications in experiments in physics and in scientific instrumentation. We discuss
normal incidence multilayer optics in the spectral region of “water window”, multilayer optics for collimation and focusing
of hard X-ray, multilayer dispersing elements for X-ray spectroscopy of high-temperature plasma, multilayer dispersing elements
for analysis of low Z-elements. Our research pays special attention to optimization of multilayer optics for projection EUV-lithography
(ψ-13nm) and short period multilayer optics. 相似文献
975.
F. Forkusuz S. Işıklı S. Akın M. Ungan A. Şenköylü N. K. Aras 《Journal of Radioanalytical and Nuclear Chemistry》2004,259(3):365-368
The standard method to diagnose and follow-up osteoporosis is the measurement of bone mineral density (BMD) using dual X-ray
absorptiometry (DEXA). Manufacturers' manuals of DEXA devices state the intrascanner coefficient of variance is less than
0.01 g/cm2. The aim of this study was to evaluate the in vivo coefficient of variance of a Lunar DPX scanner in male and female healthy
adult subjects. Average BMD for females and males were 1.170±0.091 g/cm2 and 1.272±0.115 g/cm2, respectively. Monthly phantom measurements provided and controlled by the manufacturer were 1.243±0.008 g/cm2 (range 1.222 to 1.257) and the coefficient of variance was 0.006. It is concluded that the in vivo coefficient of variance
of DEXA devices can slightly be higher than that proposed by the manufacturer.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
976.
977.
M.V. Nazarov J.H. Kang E.-J. Popovici B.S. Tsukerblat 《Solid State Communications》2005,133(3):183-186
Samples of yttrium oxide doped with trivalent europium have been prepared by ceramic techniques, under different synthesis conditions; barium chloride (BaCl2) and sodium tetraborate (Na2B4O7) were tested as flux. The improvement of luminescence properties in dependence on substitution of Eu3+ for Y3+ in the host lattice, under electron and UV excitations is demonstrated. The lattice parameter as a quantitative assessment of activator incorporation degree is proposed. The obtained results are discussed with respect to the employed processing method. 相似文献
978.
L. Villa P. D' Agati C. Mansueto C. Pellerito M. Scopelliti T. Fiore L. Nagy L. Pellerito 《应用有机金属化学》2003,17(2):106-112
Ascidia malaca gametes before fertilization incubated in 10?5 or 10?7 M solutions of tributyltin(IV) chloride, TBTCl, for 3 h appear highly damaged under transmission electron microscopy observation. Also, the fertilization process is affected by the compound: the damaged spermatozoa are present in the vitelline coat and the egg does not cleave. An increase of microbodies, structurally similar to peroxisomes, have been detected in the egg peripheral cytoplasm, probably in relation to their role in alleviating damage to some cellular components. The results have shown that the reproduction of ascidians under unfavourable environmental conditions is prevented. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
979.
M F Anjos R C H Cheng C S M Currie 《The Journal of the Operational Research Society》2004,55(5):535-541
The paper describes a methodology that has been implemented in a major British airline to find the optimal price to charge for airline tickets under one-way pricing. An analytical model has been developed to describe the buying behaviour of customers for flights over the selling period. Using this model and a standard analytical method for constrained optimization, we can find an expression for the optimal price structure for a flight. The expected number of bookings made on each day of the selling period and in each fare class given these prices can then be easily calculated. A simulation model is used to find the confidence ranges on the numbers of bookings and these ranges can be used to regulate the sale of tickets. A procedure to update the price structure based on the remaining capacity has also been developed. 相似文献
980.
Azuelos G. Benslama K. Costanzo D. Couture G. Garcia J.E. Hinchliffe I. Kanaya N. Lechowski M. Mehdiyev R. Polesello G. Ros E. Rousseau D. 《The European Physical Journal C - Particles and Fields》2004,39(2):13-24
The European Physical Journal C - We discuss possible searches for the new particles predicted by Little Higgs Models at the LHC. By using a simulation of the ATLAS detector, we demonstrate how the... 相似文献