全文获取类型
收费全文 | 277306篇 |
免费 | 2577篇 |
国内免费 | 885篇 |
专业分类
化学 | 133661篇 |
晶体学 | 4391篇 |
力学 | 14544篇 |
综合类 | 11篇 |
数学 | 50528篇 |
物理学 | 77633篇 |
出版年
2020年 | 1729篇 |
2019年 | 1923篇 |
2018年 | 12373篇 |
2017年 | 12309篇 |
2016年 | 9412篇 |
2015年 | 3004篇 |
2014年 | 3830篇 |
2013年 | 9363篇 |
2012年 | 10096篇 |
2011年 | 18090篇 |
2010年 | 11106篇 |
2009年 | 11490篇 |
2008年 | 13486篇 |
2007年 | 15512篇 |
2006年 | 6894篇 |
2005年 | 7292篇 |
2004年 | 6966篇 |
2003年 | 6981篇 |
2002年 | 5834篇 |
2001年 | 6365篇 |
2000年 | 4898篇 |
1999年 | 3669篇 |
1998年 | 2925篇 |
1997年 | 2837篇 |
1996年 | 2786篇 |
1995年 | 2553篇 |
1994年 | 2408篇 |
1993年 | 2257篇 |
1992年 | 2880篇 |
1991年 | 2795篇 |
1990年 | 2726篇 |
1989年 | 2754篇 |
1988年 | 2779篇 |
1987年 | 2787篇 |
1986年 | 2655篇 |
1985年 | 3363篇 |
1984年 | 3358篇 |
1983年 | 2642篇 |
1982年 | 2755篇 |
1981年 | 2809篇 |
1980年 | 2594篇 |
1979年 | 2929篇 |
1978年 | 2907篇 |
1977年 | 3010篇 |
1976年 | 2846篇 |
1975年 | 2574篇 |
1974年 | 2524篇 |
1973年 | 2491篇 |
1972年 | 1718篇 |
1968年 | 1715篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
982.
N. V. Shiran A. V. Gektin V. K. Komar I. M. Krasovitska V. V. Shlyahturov 《Radiation measurements》1995,24(4):435-437
Optical properties of pure and RE doped KMgF3 crystals were studied. Thermoluminescence curves are independent of the introduced impurity for all dopant besides europium. Emission, radiation damage and TL are found to be significantly dependent on the types of Eu-dopant added to the melt: europium fluoride or oxide. An intensive high temperature TL peak at 390°C in KMgF3(Eu2O3) may be used as a dosimetric one not only for ionizing but also for UV radiation. 相似文献
983.
A fast electrooptic modulation in a polymer waveguide using a ferroelectric liquid crystal has been proposed. In this device, the surface stabilized ferroelectric liquid crystal and the soft mode ferroelectric liquid crystal are used as an active material on the passive polymer waveguide, and electrooptic switching is realized by controlling the total reflection at the polymer waveguide-liquid crystal interface. The response time is of the order of several microseconds. The analogue electrooptic modulation in the waveguide is realized using the field induced linear molecular tilt of the electroclinic effect in the soft mode ferroelectric liquid crystal. 相似文献
984.
Ch. M. Hardalov K. D. Stefanov D. Sueva 《Applied Physics A: Materials Science & Processing》1995,61(2):107-109
Deep-Level Transient Spectroscopy (DLTS) measurements were carried out on silicon p+nn+ diodes before and after irradiation with fast neutrons at room temperature with fluences 5.5×1011 and 1.0×1012 n/cm2. It was found out, that all preexisting defects decreased their amplitudes during irradiation, while only one defect, identified as a single-charged divacancy, increased in amplitude. An interpretation is proposed in terms of the cluster model, and the applicability of the DLTS is discussed. 相似文献
985.
986.
987.
The current status of the R & D activities is presented on electron beam processing of polymers being carried out at TRCRE. Topics included are sterilization of medical products, graft polymers for selective separation or absorbents and curing of liquid prepolymer-monomer systems. 相似文献
988.
989.
D. Kast A. Jungclaus K.P. Lieb M. Górska G. de Angelis P.G. Bizzeti A. Dewald C. Fahlander H. Grawe R. Peusquens M. De Poli H. Tiesler 《The European Physical Journal A - Hadrons and Nuclei》1998,3(2):115-128
In the neutron deficient isotopes 104,105In lifetimes of high spin states in the range from 0.5 ps to 600 ps have been measured in a coincidence recoil distance Doppler
shift (RDDS) experiment. By combining the Doppler shift attenuation (DSA) and RDDS methods at few μm flight distances, the
problem of delayed feeding has been avoided and very short lifetimes in the range 0.5–0.8 ps have been determined. Shell model
calculations with strong restrictions for the neutron orbitals reveal good agreement with experimental level energies and
still fair agreement for most measured B(M1) and B(E2) values.
Received: 30 June 1998 相似文献
990.
W. Loveland K. Aleklett J. O. Liljenzin G. T. Seaborg 《Journal of Radioanalytical and Nuclear Chemistry》1992,160(1):181-189
The use of radioanalytical techniques to study heavy ion induced nuclear reactions offers some distinct advantages over conventional physical techniques. Among these are (a) unit Z and A resultion in detecting the reaction products (b) high sensitivity for low probability events (c) lack of low energy thresholds or cutoffs in measuring reactcion product energy spectcra (d) economical use of accelerator time and (e) simple, portable experimental apparatus allowing broad survey measurements of reaction mechanisms at a variety of nuclear particle accelerators. We describe examples of these advantages from our research in nuclear chemistry. 相似文献