全文获取类型
收费全文 | 4440篇 |
免费 | 836篇 |
国内免费 | 307篇 |
专业分类
化学 | 689篇 |
晶体学 | 23篇 |
力学 | 313篇 |
综合类 | 50篇 |
数学 | 1944篇 |
物理学 | 2564篇 |
出版年
2024年 | 14篇 |
2023年 | 45篇 |
2022年 | 111篇 |
2021年 | 119篇 |
2020年 | 109篇 |
2019年 | 122篇 |
2018年 | 123篇 |
2017年 | 176篇 |
2016年 | 164篇 |
2015年 | 142篇 |
2014年 | 245篇 |
2013年 | 287篇 |
2012年 | 261篇 |
2011年 | 441篇 |
2010年 | 397篇 |
2009年 | 539篇 |
2008年 | 427篇 |
2007年 | 387篇 |
2006年 | 289篇 |
2005年 | 187篇 |
2004年 | 180篇 |
2003年 | 146篇 |
2002年 | 96篇 |
2001年 | 83篇 |
2000年 | 73篇 |
1999年 | 67篇 |
1998年 | 59篇 |
1997年 | 45篇 |
1996年 | 41篇 |
1995年 | 38篇 |
1994年 | 25篇 |
1993年 | 22篇 |
1992年 | 17篇 |
1991年 | 16篇 |
1990年 | 11篇 |
1989年 | 13篇 |
1988年 | 12篇 |
1987年 | 6篇 |
1986年 | 9篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1959年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有5583条查询结果,搜索用时 15 毫秒
61.
62.
63.
同位素稀释-火花源质谱法分析人参样品中微量元素 总被引:2,自引:0,他引:2
本文采用同位素稀释-火花源质谱法定量分析了吉林野山参,园参及高丽参中30多种微量元素的含量。测定下限2μg/g,相对标准偏差在5~28%以内。 相似文献
64.
Arakawa R Shimomae Y Morikawa H Ohara K Okuno S 《Journal of mass spectrometry : JMS》2004,39(8):961-965
A low molecular mass polyester was analyzed by desorption/ionization on porous silicon (DIOS) mass spectrometry. The results were compared with those of matrix-assisted laser desorption ionization (MALDI) mass spectrometry using matrixes of alpha-cyano-4-hydroxycinnamic acid (CHCA) and 10,15,20-tetrakis(pentafluorophenyl)porphyrin (F20TPP). The CHCA matrix was not suitable for characterization of low molecular mass components of the polyester because the matrix-related ions interfered with the component ions. On the other hand, the F20TPP matrix showed no interference because no matrix-related ions appeared below m/z 822. However, the solvent selection for determining optimal conditions of sample preparation was limited, because F20TPP does not dissolve readily in any of the available organic solvents. In the DIOS spectra, the polymer ions were observed at high sensitivity without a contaminating ion. No matrix is needed for DIOS spectra of low molecular mass polyesters, facilitating sample preparation and selectivity of a precursor ion in post-source decay measurements. 相似文献
65.
M. Nagy 《Colloid and polymer science》1985,263(3):245-265
66.
The differential equations and the boundary conditions for the nonequilibrium binary distribution function of an unsymmetrical binary electrolyte are derived from the Ebeling-Falkenhagen continuity equation. The connection between the Onsager reciprocal relation and the binary distribution functions is shown. Further, Feistel's result for thec logc contribution to the conductance is extended to unsymmetrical binary electrolytes. The reason for the difference between Feistel's and Chen'sc logc term is explained, and the significance of Onsager's reciprocal relation for the calculation ofc logc and higher-concentration contributions of the conductance is discussed. 相似文献
67.
Pentacoordinate complex cations of the general formula [(C6F5)2SbL3]3+ stabilized as solid salts in combination with tetraphenylborate (BPh4), tetrafluorobroate (BF4) anions, where L=DMSO, Ph3AsO, PyO, DMF, α-, β- and γ-picoline have been isolated. The newly formed complexes were characterized by elemental analysis, molar conductance measurements, solid-state IR and and NMR. From these results, a five-fold coordination around antimony was required. 相似文献
68.
The boxes contained kiwifruits were irradiated with cobalt-60 γ-rays at different dosages (0.6 , 1.8 and 3.6 KGy) and stored in a room ventilated at night, the natural ambient air being used as cool source.The results showed that the treatment which fruits irradiated with 0.6 KGy was the best after 85 days. It gave the normal-fruit rate of 95.10%, fruit flesh hardness of 4.10 Kg · cm-2, fresh and plump fruits, good quality and less Vc loss. 相似文献
69.
J. Rodriguez-Añón J. Prouupin M. González-Añón L. Núñez-Regueira 《Journal of Thermal Analysis and Calorimetry》1998,52(3):1005-1012
The heating values of municipal solid waste generated in three towns with a population of less than 50 000, situated in Galicia
(Spain), were measured with a static bomb calorimeter. Samples of raw refuse were burnt either as received or after sorting
of the different combustible components. A study was made of samples from controlled and uncontrolled landfills.
The calorific values were compared with those corresponding to a commercial residual derived fuel in order to study the possibility
of using municipal solid waste as a source of recovered energy.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
70.
《Surface and interface analysis : SIA》2004,36(10):1417-1422
A Monte‐Carlo simulation approach has been applied to describe the spatial distribution of characteristic x‐rays in W/Al film targets of different combinations of film thicknesses for the optimal design of a small‐sized x‐ray source having a high x‐ray intensity. The result has led to optimal combinations of W and Al film targets for 100 kV electrons, e.g. W(1 µm)/Al(20 µm), W(3 µm)/Al(15 µm) and W(5 µm)/Al(8 µm). These Al/W targets could be used as x‐ray sources for a medical instrument currently under development. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献