全文获取类型
收费全文 | 297854篇 |
免费 | 1556篇 |
国内免费 | 326篇 |
专业分类
化学 | 136853篇 |
晶体学 | 4651篇 |
力学 | 16868篇 |
综合类 | 3篇 |
数学 | 41998篇 |
物理学 | 99363篇 |
出版年
2021年 | 3094篇 |
2020年 | 3412篇 |
2019年 | 4189篇 |
2018年 | 6225篇 |
2017年 | 6438篇 |
2016年 | 7937篇 |
2015年 | 3516篇 |
2014年 | 6871篇 |
2013年 | 12104篇 |
2012年 | 10107篇 |
2011年 | 11780篇 |
2010年 | 9972篇 |
2009年 | 10127篇 |
2008年 | 11399篇 |
2007年 | 11192篇 |
2006年 | 9967篇 |
2005年 | 8597篇 |
2004年 | 8350篇 |
2003年 | 7760篇 |
2002年 | 8049篇 |
2001年 | 7663篇 |
2000年 | 6056篇 |
1999年 | 4486篇 |
1998年 | 4263篇 |
1997年 | 4122篇 |
1996年 | 3733篇 |
1995年 | 3296篇 |
1994年 | 3358篇 |
1993年 | 3374篇 |
1992年 | 3379篇 |
1991年 | 3786篇 |
1990年 | 3787篇 |
1989年 | 3794篇 |
1988年 | 3545篇 |
1987年 | 3628篇 |
1986年 | 3320篇 |
1985年 | 3850篇 |
1984年 | 4083篇 |
1983年 | 3488篇 |
1982年 | 3686篇 |
1981年 | 3372篇 |
1980年 | 3132篇 |
1979年 | 3621篇 |
1978年 | 3686篇 |
1977年 | 3855篇 |
1976年 | 3928篇 |
1975年 | 3671篇 |
1974年 | 3527篇 |
1973年 | 3688篇 |
1972年 | 3177篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
961.
We present a study of the temporal compression of nanosecond laser pulses resulting from the coherent control peculiarities of the propagation dynamics in a regime of electromagnetically induced transparency. We describe the general theoretical framework and discuss the crucial conditions required in order to experimentally realize such a temporal compression scheme. A proof-of-concept experimental realization of a scheme of this type in a sample of hot sodium vapors is currently being implemented: we describe in detail the experimental setup designed for this purpose. 相似文献
962.
Yu. V. Kaletina V. M. Schastlivtsev E. A. Fokina 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(12):1667-1673
The effect of magnetic treatment on the isothermal martensitic transformation in the Fe-24% Ni-4% Mn alloy has been investigated. The martensitic transformation in a dc magnetic field at liquid-helium temperature has been analyzed. 相似文献
963.
V. I. Zubkov I. S. Shulgunova A. V. Solomonov M. Geller A. Marent D. Bimberg A. E. Zhukov E. S. Semenova V. M. Ustinov 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(1):106-108
In this work, charge-carrier capture by an array of self-assembled InAs/GaAs quantum dots was directly observed for the first time by capacitance recharge. It is proposed to process the obtained transient-capture data by a similar method to that used for emission, by the box-car method. The capture activation energies are determined and compared with the emission activation energies. 相似文献
964.
L. A. Bityutskaya V. V. Distler V. V. Kryachko M. A. Yudovskaya M. V. Grechkina E. V. Bogatikov 《Physics of the Solid State》2007,49(7):1382-1386
Nanostructuring of natural isoferroplatinum crystals is revealed by atomic-force microscopy for the first time. Typical scales of ~30, 50, and 100 nm are determined and the self-affine character of their relation is established using a wavelet analysis. 相似文献
965.
Milind V. Kulkarni Annamraju Kasi Viswanath R. Marimuthu Tanay Seth 《Journal of polymer science. Part A, Polymer chemistry》2004,42(8):2043-2049
Spectroscopic [UV–visible and Fourier transform IR (FTIR)] and thermal properties of chemically synthesized polyanilines are found to be affected by varying the protonation media (acetic, citric, oxalic, and tartaric acid). The optical spectra show the presence of a greater fraction of fully oxidized insulating pernigraniline phase in polyaniline doped with acetic acid. In contrast, the selectivity in the formation of the conducting phase is higher in oxalic acid as a protonic acid media. The FTIR spectra of these polymers reveal a higher ratio of the relative intensities of the quinoid to benzenoid ring modes in acetic acid doped polyaniline. Scanning electron micrographs revealed a sponge‐like structure derived from the aggregation of the small granules in acetic acid and oxalic acid doped polyaniline. A three‐step decomposition pattern is observed in all the polymers, regardless of the protonic acid used for the doping. The second step loss related to the loss of dopant is found to be higher in the oxalic acid doped polymer. In accordance with these results the conductivity is also found to be higher in oxalic acid doped material. The temperature dependent conductivity measurements show the thermal activated behavior in all the polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2043–2049, 2004 相似文献
966.
The surface of polystyrene was modified with the bovine serum albumin-Tween 80 complex. The adsorption of the complex and the formation of films on the surface of polystyrene were studied using the piezoelectric weighing method. The state of the modified surface was evaluated by contact angle measurements. The stability of the modifying layer was determined based on the critical interfacial energy values of the surface equilibrated with water. A conclusion was drawn that the complex can be effectively used to enhance the biocompatibility of polymer materials. 相似文献
967.
Sanzhizhapov D. B. Tonevitskii Yu. V. Mognonov D. M. Doroshenko Yu. E. 《Russian Journal of Applied Chemistry》2003,76(4):619-622
New polyimidates were prepared from bisphenols and mono- and dicarboxylic acid imidoyl chlorides. The structures of the polymers were determined, and their physicochemical, chemical, and thermal properties were studied. The possibility of preparing film and compression materials with good mechanical characteristics from these polymers was examined. 相似文献
968.
The effect of bifractional composition of conducting filler on the electrical and rheological properties of oligomeric compound was studied. 相似文献
969.
Raman scattering in glasses is investigated theoretically. The experimental Raman spectra of glasses exhibit a low-frequency peak (at ~10 cm?1) that, as a rule, is attributed to vibrational modes of nanometer-sized structural units (nanocrystallites). It is established that the elastic moduli of nanocrystallites must necessarily be dependent on their sizes due to the Laplace pressure effect. A theory of the low-frequency peak is constructed using a realistic size distribution function of nanocrystallites with allowance made for the Laplace pressure effect and the dissipation of vibrational energy. Within this theory, the shape of the low-frequency peak and its evolution with temperature can be analyzed quantitatively. The proposed approach offers a physical interpretation of the experimental data and provides insight into the relation of the characteristic nanocrystallite sizes to the elastic moduli and surface tension coefficients of materials. 相似文献
970.
V. G. Sutyrin 《Journal of Applied Mathematics and Mechanics》1991,55(6):877-886
The stress relaxation process is linked to the change with time of the metric stress tensor of the medium. Possible types of thermodynamically justified relaxation equations are discussed. 相似文献