全文获取类型
收费全文 | 130794篇 |
免费 | 6348篇 |
国内免费 | 5552篇 |
专业分类
化学 | 69508篇 |
晶体学 | 1644篇 |
力学 | 7152篇 |
综合类 | 408篇 |
数学 | 21195篇 |
物理学 | 42787篇 |
出版年
2022年 | 1617篇 |
2021年 | 2121篇 |
2020年 | 2482篇 |
2019年 | 2678篇 |
2018年 | 4134篇 |
2017年 | 4321篇 |
2016年 | 4368篇 |
2015年 | 3113篇 |
2014年 | 4144篇 |
2013年 | 5872篇 |
2012年 | 8444篇 |
2011年 | 7971篇 |
2010年 | 6321篇 |
2009年 | 6018篇 |
2008年 | 5369篇 |
2007年 | 5072篇 |
2006年 | 4667篇 |
2005年 | 7995篇 |
2004年 | 7087篇 |
2003年 | 5144篇 |
2002年 | 3438篇 |
2001年 | 2969篇 |
2000年 | 2179篇 |
1999年 | 1851篇 |
1998年 | 1704篇 |
1997年 | 1448篇 |
1996年 | 1378篇 |
1995年 | 1153篇 |
1994年 | 1227篇 |
1993年 | 1154篇 |
1992年 | 1265篇 |
1991年 | 1310篇 |
1990年 | 1267篇 |
1989年 | 1153篇 |
1988年 | 1025篇 |
1987年 | 979篇 |
1986年 | 936篇 |
1985年 | 967篇 |
1984年 | 950篇 |
1983年 | 850篇 |
1982年 | 823篇 |
1979年 | 834篇 |
1978年 | 837篇 |
1977年 | 826篇 |
1976年 | 997篇 |
1975年 | 851篇 |
1974年 | 888篇 |
1973年 | 896篇 |
1972年 | 791篇 |
1971年 | 768篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
821.
L Jirovetz G Buchbauer W J?ger A Woidich A Nikiforov 《Biomedical chromatography : BMC》1992,6(3):133-134
After inhalation experiments with sandalwood oil and the pure fragrance compounds coumarin and alpha-terpineol, substances were detected and measured in the blood samples of test animals (mice) using gas chromatography/mass spectrometry (GC/MS) (MID) in connection with GC/FTIR (SWC), GC/AES (carbon and oxygen trace) and flame ionization detection/gas chromatography. Using tiglinic acid benzyl ester as the internal standard the following concentrations in serum could be found: alpha-santalol 6.1 ng/mL, beta-santalol 5.3 ng/mL and alpha-santalene 0.5 ng/mL. In separate inhalation experiments with coumarin and with alpha-terpineol the corresponding concentrations were 7.7 ng/mL and 6.9 ng/mL, respectively. 相似文献
822.
Yu. N. Obukhov 《General Relativity and Gravitation》1992,24(2):121-128
Cosmological models for a universe with expansion and rotation are considered. In particular, we analyse some effects of the universal rotation on the observational cosmology. It is shown that pure cosmic rotation does not produce neither causality voilations, nor parallax effects, nor anisotropy of the microwave background radiation. It can be detected by studying angular dependence of standard cosmological tests, and is directly measurable via polarization observations. The latter are used to obtain experimental estimates for the direction and value of the rotation of the universeThis essay received the third award from the Gravity Research Foundation, 1991 — Ed. 相似文献
823.
824.
S. A. Chernyak O. V. Shekhter N. L. Sergovskaya Yu. S. Tsizin 《Chemistry of Heterocyclic Compounds》1992,28(7):832-834
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 994–996, July, 1992. 相似文献
825.
D. Yu. Grigor'ev 《Journal of Mathematical Sciences》1992,59(3):823-841
This paper presents an algorithm of polynomial complexity for finding greatest common (right) divisors of families of linear ordinary differential operators. An algorithm is presented for factorization of operators into the product of irreducible operators with complexity significantly better than that of previously known algorithms. Estimates are given for the coefficients of the expansion of the fundamental solution of the corresponding linear differential equation.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova Akademii Nauk SSSR, Vol. 176, pp. 68–103, 1989. 相似文献
826.
827.
828.
X. Y. Yang H. C. Gao X. L. Tan H. Z. Yuan G. Z. Cheng S. Z. Mao S. Zhao L. Zhang J. Y. An J. Y. Yu Y. R. Du 《Colloid and polymer science》2004,282(3):280-286
1H chemical shift changes of sodium 4-decyl naphthalene sulfonate (SDNS) at 313 K show that its critical micellar concentration lies between 0.82 and 0.92 mmol/dm3, which is in the same range as that of the previous study at 298 K. The spin–lattice relaxation time, spin–spin relaxation time and two-dimensional nuclear Overhauser enhancement spectroscopy experiments give information about the structure of the SDNS micelle and the dynamics of the molecules in the micelle. The size of the SDNS micelle remains almost unchanged in the temperature range from 298 to 313 K as deduced by analyzing the self-diffusion coefficient. Special arrangement of the naphthyl rings of SDNS in the micelles affects the packing of these hydrophobic chains. The methylene groups of the alkyl chain nearest the naphthalene groups penetrate into the aromatic region, which results in a more tightly packed hydrophobic micellar core than that of sodium dodecyl sulfonate. 相似文献
829.
在教学中加强对学生非智力因素的培养 总被引:1,自引:0,他引:1
仅仅依靠智力因素的作用,并不能充分地理解学习过程中的成功和失败,人们越来越多地注意到非智力因素在学习过程中所起的巨大作用。中国在这方面的格言甚多;“哀莫过于心死,愁莫过于无志”;“勤能补拙”;“笨鸟先飞”等都是说非智力因素的重要性。 相似文献
830.