全文获取类型
收费全文 | 609127篇 |
免费 | 6512篇 |
国内免费 | 1672篇 |
专业分类
化学 | 269238篇 |
晶体学 | 8042篇 |
力学 | 24735篇 |
综合类 | 10篇 |
数学 | 75130篇 |
物理学 | 163449篇 |
无线电 | 76707篇 |
出版年
2020年 | 3494篇 |
2019年 | 3620篇 |
2018年 | 12849篇 |
2017年 | 13703篇 |
2016年 | 11065篇 |
2015年 | 5938篇 |
2014年 | 7776篇 |
2013年 | 21564篇 |
2012年 | 19961篇 |
2011年 | 31072篇 |
2010年 | 20451篇 |
2009年 | 20980篇 |
2008年 | 29365篇 |
2007年 | 33163篇 |
2006年 | 19851篇 |
2005年 | 24798篇 |
2004年 | 20103篇 |
2003年 | 18275篇 |
2002年 | 16091篇 |
2001年 | 16601篇 |
2000年 | 13421篇 |
1999年 | 10765篇 |
1998年 | 9243篇 |
1997年 | 8869篇 |
1996年 | 8834篇 |
1995年 | 8212篇 |
1994年 | 7884篇 |
1993年 | 7678篇 |
1992年 | 8286篇 |
1991年 | 8108篇 |
1990年 | 7605篇 |
1989年 | 7203篇 |
1988年 | 7339篇 |
1987年 | 6320篇 |
1986年 | 6013篇 |
1985年 | 8237篇 |
1984年 | 8388篇 |
1983年 | 7045篇 |
1982年 | 7404篇 |
1981年 | 7215篇 |
1980年 | 6989篇 |
1979年 | 7120篇 |
1978年 | 7223篇 |
1977年 | 7037篇 |
1976年 | 7016篇 |
1975年 | 6819篇 |
1974年 | 6667篇 |
1973年 | 6992篇 |
1972年 | 4304篇 |
1971年 | 3357篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
1.
Journal of Fluorescence - This report describes a combined immunofluorescence and fluorescence viability stain applied as one staining solution for rapid detection of live Legionella... 相似文献
2.
Yang T. L. Kao C. L. Kuo C. E. Yeh H. C. Li W. J. Li H. T. Chen C. Y. 《Chemistry of Natural Compounds》2022,58(5):825-827
Chemistry of Natural Compounds - A novel bibenzyl derivative, hydrangchinenin (1), was isolated from the stems of Hydrangea chinensis Maxim. (Hydrangeaceae). Its structure was determined on the... 相似文献
3.
Wireless Personal Communications - Chronic kidney disease (CKD) is a gradual loss of kidney function over the period of time and it is irrevocable once functionality reaches the critical state.... 相似文献
4.
Kinetics and Catalysis - The results of studies in the field of synthesis and characterization of layered double hydroxides (LDHs) obtained using solid-phase reactions are summarized. The effect of... 相似文献
5.
Petrov P. A. Filippova E. A. Kompankov N. B. Sukhikh T. S. Sokolov M. N. 《Journal of Structural Chemistry》2022,63(3):470-475
Journal of Structural Chemistry - A new polymorph of the [ReCl3(MeCN)(PPh3)2] complex is synthesized and characterized by single crystal X-ray diffraction (XRD). Its recrystallization from the... 相似文献
6.
Tsyganova S. I. Fetisova O. Yu. Mazurova E. N. Taran O. P. Kuznetsov B. N. 《Russian Journal of Applied Chemistry》2022,95(3):408-416
Russian Journal of Applied Chemistry - A method for the disposal of hydrolysis lignin waste based on its modification with ZnCl2 and FeCl3 and subsequent carbonization at 800°C was proposed.... 相似文献
7.
Roopa K. P. Keshavamurthy K. Mahesh B. Veena K. P. Shankara B. S. Basavaiah K. 《Journal of Applied Spectroscopy》2022,89(4):809-818
Journal of Applied Spectroscopy - Three simple, sensitive, precise, and rapid spectrophotometric methods are developed and optimized for the assay of vardenafil in pharmaceutical formulations. The... 相似文献
8.
Shannon Lee Scott L. Carnahan Georgiy Akopov Philip Yox Lin-Lin Wang Aaron J. Rossini Kui Wu Kirill Kovnir 《Advanced functional materials》2021,31(16):2010293
Noncentrosymmetric (NCS) tetrel pnictides have recently generated interest as nonlinear optical (NLO) materials due to their second harmonic generation (SHG) activity and large laser damage threshold (LDT). Herein nonmetal-rich silicon phosphides RuSi4P4 and IrSi3P3 are synthesized and characterized. Their crystal structures are reinvestigated using single crystal X-ray diffraction and 29Si and 31P magic angle spinning NMR. In agreement with previous report RuSi4P4 crystallizes in NCS space group P1, while IrSi3P3 is found to crystallize in NCS space group Cm, in contrast with the previously reported space group C2. A combination of DFT calculations and diffuse reflectance measurements reveals RuSi4P4 and IrSi3P3 to be wide bandgap (Eg) semiconductors, Eg = 1.9 and 1.8 eV, respectively. RuSi4P4 and IrSi3P3 outperform the current state-of-the-art infrared SHG material, AgGaS2, both in SHG activity and laser inducer damage threshold. Due to the combination of high thermal stabilities (up to 1373 K), wide bandgaps (≈2 eV), NCS crystal structures, strong SHG responses, and large LDT values, RuSi4P4 and IrSi3P3 are promising candidates for longer wavelength NLO materials. 相似文献
9.
Varfolomeev S. D. Panin A. A. Semenova N. A. Ublinskiy M. V. Akhadov T. A. Bykov V. I. Tsybenova S. B. 《Russian Chemical Bulletin》2022,71(3):591-594
A kinetic study of the effect of thermoheliox (inhalation of a helium and oxygen mixture, 70 °C) on the functional hemodynamics of the human brain by functional magnetic resonance imaging was carried out. The dynamic responses of the BOLD signal were found to be biphasic. An empirical equation describing the first phase of the hemodynamic response to visual stimulus was proposed. It was shown that preliminary inhalation of thermoheliox stimulates the hemodynamic responses by slowing down the vasoconstriction.
相似文献10.
Experimental Mechanics - Temperature gradients significantly affect the material fatigue process. A reliable and robust test procedure is needed for quantifying the effects of temperature gradients... 相似文献