全文获取类型
收费全文 | 313298篇 |
免费 | 2995篇 |
国内免费 | 1340篇 |
专业分类
化学 | 152455篇 |
晶体学 | 4505篇 |
力学 | 15616篇 |
综合类 | 61篇 |
数学 | 48040篇 |
物理学 | 96956篇 |
出版年
2019年 | 1898篇 |
2018年 | 10884篇 |
2017年 | 11743篇 |
2016年 | 7525篇 |
2015年 | 3225篇 |
2014年 | 3652篇 |
2013年 | 8995篇 |
2012年 | 11725篇 |
2011年 | 21134篇 |
2010年 | 13308篇 |
2009年 | 13230篇 |
2008年 | 18792篇 |
2007年 | 22183篇 |
2006年 | 8559篇 |
2005年 | 13925篇 |
2004年 | 10109篇 |
2003年 | 9326篇 |
2002年 | 7325篇 |
2001年 | 6860篇 |
2000年 | 5370篇 |
1999年 | 3707篇 |
1998年 | 3086篇 |
1997年 | 3028篇 |
1996年 | 3189篇 |
1995年 | 2722篇 |
1994年 | 2809篇 |
1993年 | 2658篇 |
1992年 | 2894篇 |
1991年 | 2967篇 |
1990年 | 2776篇 |
1989年 | 2695篇 |
1988年 | 2648篇 |
1987年 | 2586篇 |
1986年 | 2596篇 |
1985年 | 3389篇 |
1984年 | 3466篇 |
1983年 | 2900篇 |
1982年 | 3136篇 |
1981年 | 2904篇 |
1980年 | 2699篇 |
1979年 | 2896篇 |
1978年 | 3112篇 |
1977年 | 3065篇 |
1976年 | 3125篇 |
1975年 | 2848篇 |
1974年 | 2959篇 |
1973年 | 3047篇 |
1972年 | 2358篇 |
1971年 | 1871篇 |
1968年 | 1761篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
162.
A. L. Apanasenko A. V. Kuznichenko Yu. B. Govyadovskii V. G. Yakunin 《Journal of Applied Spectroscopy》1991,54(3):271-276
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 3, pp. 438–444, March, 1991. 相似文献
163.
Rainer Löwen 《Journal of Geometry》1989,36(1-2):110-116
We prove that a spread S over a locally compact nondlscrete field F defines a topological translation plane if and only if the spread is compact. For F=R, this is implicit in Breuning's thesis [Bre], cf. [B 2]. For the proof, we describe the point set of the projective translation plane as a quotient space of some projective space, with identifications taking place in one hyperplane. This is new even for F=R. 相似文献
164.
L. Tong Y. Tian Q. Y. Wang Y. S. Ling 《International Journal of Infrared and Millimeter Waves》2006,27(9):1307-1314
The paper introduces a special system calibration technology in s-parameters measurement of microwave and millimeter wave
devices. The 8-term errors module is built by analyzing the signals flowing in the measurement system. Then the calibration
technology using non-standard kits is designed on the base. Finally, the experiment using the calibration technology is introduced. 相似文献
165.
V. Yu. Baranovskii L. L. Yasina M. V. Motyakin I. I. Aliev S. Shenkov M. Dimitrov N. Lambov A. M. Wasserman 《Polymer Science Series A》2006,48(12):1304-1309
Partially water-swellable polymer networks were synthesized on the basis of poly(acrylic acid) and various macrodiisocyanates. Hydrophilic and hydrophobic local regions were revealed in swollen networks (hydrogels) by means of the spin probe technique. The local mobility in hydrophobic regions depends on the macrodiisocyanate structure; however, it is substantially lower than that in hydrophilic regions for all gels. It was assumed that the presence of hydrophobic and hydrophilic regions and the difference in their local dynamics must have a substantial effect on the pharmacokinetics of release of drugs immobilized in these hydrogels. 相似文献
166.
The quantitative rainbow schlieren deflectometry (RSD) technique was applied to measure temperature and oxygen concentration in an axisymmetric hydrogen gas-jet diffusion flame burning in quiescent air at fuel jet exit Reynolds number of 70. Schlieren measurements were compared with conventional measurements using a thermocouple and a gas-sampling probe. Good agreement between the two measurement techniques was achieved on the fuel-lean side of the flame. 相似文献
167.
This study addresses the problem of the automatic flow regime identification in two-phase flows in pipes. A novel wavelet transform-based approach is proposed and validated using time series of differential pressure fluctuations. The experimental data on the differential pressure measured in a vertically installed Venturi meter for air-water flow were analyzed and found to be appropriate for flow regime identification. The wavelet spectrum of the measured signal is shown to characterize the flow patterns completely, and the vector of the wavelet variances is proposed as the characteristic vector for use in an on-line flow regime identification system. 相似文献
168.
L. Aggoun 《Mathematical and Computer Modelling》2002,36(11-13)
In this paper, finite-dimensional recursive filters for space-time Markov random fields are derived. These filters can be used with the expectation maximization (EM) algorithm to yield maximum likelihood estimates of the parameters of the model. 相似文献
169.
170.
A. R. Volkov B. V. Shul'gin T. I. Polupanova V. N. Lebedev A. A. Nagornyi V. L. Petrov Yu. F. Kargin 《Journal of Applied Spectroscopy》1991,54(6):585-590
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 6, pp. 970–975, June, 1991. 相似文献