全文获取类型
收费全文 | 563801篇 |
免费 | 6008篇 |
国内免费 | 2191篇 |
专业分类
化学 | 278232篇 |
晶体学 | 8510篇 |
力学 | 28084篇 |
综合类 | 68篇 |
数学 | 79748篇 |
物理学 | 177358篇 |
出版年
2021年 | 4139篇 |
2020年 | 4641篇 |
2019年 | 5100篇 |
2018年 | 12727篇 |
2017年 | 13379篇 |
2016年 | 12664篇 |
2015年 | 6553篇 |
2014年 | 9623篇 |
2013年 | 22734篇 |
2012年 | 20982篇 |
2011年 | 30269篇 |
2010年 | 20888篇 |
2009年 | 20694篇 |
2008年 | 27197篇 |
2007年 | 29576篇 |
2006年 | 18596篇 |
2005年 | 20795篇 |
2004年 | 17254篇 |
2003年 | 15658篇 |
2002年 | 14136篇 |
2001年 | 15230篇 |
2000年 | 11569篇 |
1999年 | 8730篇 |
1998年 | 7310篇 |
1997年 | 7101篇 |
1996年 | 6956篇 |
1995年 | 6000篇 |
1994年 | 6026篇 |
1993年 | 5780篇 |
1992年 | 6370篇 |
1991年 | 6560篇 |
1990年 | 6218篇 |
1989年 | 6091篇 |
1988年 | 5824篇 |
1987年 | 5864篇 |
1986年 | 5672篇 |
1985年 | 7293篇 |
1984年 | 7428篇 |
1983年 | 6191篇 |
1982年 | 6419篇 |
1981年 | 6004篇 |
1980年 | 5815篇 |
1979年 | 6211篇 |
1978年 | 6394篇 |
1977年 | 6333篇 |
1976年 | 6363篇 |
1975年 | 5937篇 |
1974年 | 5984篇 |
1973年 | 6114篇 |
1972年 | 4530篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
891.
892.
893.
The transverse momentum spectra for pions observed by WA80 and NA35 collaborations are analysed within a fireball model with collective isentropic expansion and a realistic freeze-out criterion. By varing the initial state of the fireball, an excellent fit to the data is achieved for the whole measured range ofP T . Slight differences in the data for the spectral slopes from central and pheripheral collisions originate in our model from the difference in the size of the fireball and in the number of participating nucleons in central and peripheral collisions. Using additional information from two-pion correlations, we can extrapolate our model back from the freeze-out point (determined from the spectra) to the initial state; we find that an initial energy density of 1.5–2GGeV/fm3 is sufficient to explain the data from central O+Au collisions at 200A GeV. 相似文献
894.
Institute of Automated Control Systems and Radioelectronics, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 32, No. 1, pp. 94–105, January, 1989. 相似文献
895.
Time structure of iodine laser pulse in the free running mode of operation was studied using the power amplifier of laser system PERUN as the laser oscillator. Two characteristic shapes of laser pulse correspond to different regimes of laser operation, the existence of which is ascribed to the critical concentration of I2 molecules. Simultaneously an additional chemical pumping was proved at least in the initial phase of photodissociation and in a late-time lasing after the end of flashlamps pumping light. 相似文献
896.
897.
Summary The meaning of linear absorbing boundary conditions for periodic water waves in elliptical approaches is discussed. It is
found that the direction of propagation of the waves must be known for reliable boundary conditions and that the energy dissipation
of waves running parallel to a boundary in general cannot be modelled in the framework of a linear theory.
Work presented at the Euromech Colloquium 240 on ?Dispersive waves in dissipative fluids?, Bologna, August 30–September 2,
1988. 相似文献
898.
In an effort to clarify the role of controlled oxygen exposure in the synthesis of LaBa2Cu3Oy samples which achieve zero resistivity above 90 K, we have prepared samples of La(1+x)Ba(2–x)Cu3Oy with x approximately equal to 0 and with y varying between 6.22 and 7.00. We find that for large values of y, 6.88相似文献
899.
Summary We have estimated and measured the daily thermal expansion of an oceanographic platform. This has been found negligible as
far as the calibration of a satellite altimeter is concerned. 相似文献
900.
V. A. Popova I. V. Podgornaya V. G. Lundina L. I. Kurnikova A. I. Tarasov 《Russian Chemical Bulletin》1987,36(11):2361-2364
Conclusions Complex compounds of bisacyl derivatives of diaminodibenzo-18-crown-6 ether are active catalysts of the two stages of the synthesis of poly(ethylene terephthalate).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2544–2547, November. 1987. 相似文献