全文获取类型
收费全文 | 10667篇 |
免费 | 2009篇 |
国内免费 | 1374篇 |
专业分类
化学 | 7460篇 |
晶体学 | 223篇 |
力学 | 668篇 |
综合类 | 153篇 |
数学 | 1185篇 |
物理学 | 4361篇 |
出版年
2024年 | 32篇 |
2023年 | 205篇 |
2022年 | 437篇 |
2021年 | 463篇 |
2020年 | 518篇 |
2019年 | 532篇 |
2018年 | 465篇 |
2017年 | 458篇 |
2016年 | 610篇 |
2015年 | 644篇 |
2014年 | 744篇 |
2013年 | 970篇 |
2012年 | 1074篇 |
2011年 | 987篇 |
2010年 | 766篇 |
2009年 | 689篇 |
2008年 | 720篇 |
2007年 | 619篇 |
2006年 | 502篇 |
2005年 | 441篇 |
2004年 | 323篇 |
2003年 | 270篇 |
2002年 | 238篇 |
2001年 | 199篇 |
2000年 | 147篇 |
1999年 | 197篇 |
1998年 | 105篇 |
1997年 | 134篇 |
1996年 | 117篇 |
1995年 | 111篇 |
1994年 | 69篇 |
1993年 | 67篇 |
1992年 | 39篇 |
1991年 | 41篇 |
1990年 | 30篇 |
1989年 | 19篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 16篇 |
1985年 | 12篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1957年 | 3篇 |
1936年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
The Ramanujan Journal - Let $$k\ge 2$$ be an even integer, and let M be a positive integer. We prove a hybrid subconvexity bound for $$L(1/2,\text {sym}^2 f\otimes \chi )$$ with the associated... 相似文献
72.
In this paper, we are interested in the regularity estimates of the nonnegative viscosity super solution of the $β$−biased infinity Laplacian equation $$∆^β_∞u = 0,$$ where $β ∈ \mathbb{R}$ is a fixed constant and $∆^β_∞u := ∆^N_∞u + β|Du|,$ which arises from the random game named biased tug-of-war. By studying directly the $β$−biased infinity Laplacian equation, we construct the appropriate exponential cones as barrier functions to establish a key estimate. Based on this estimate, we obtain the Harnack inequality, Hopf boundary point lemma, Lipschitz estimate and the Liouville property etc. 相似文献
73.
4-Fluorinated UDP-MurNAc pentapeptide, 2, has been synthesized. In our previous study, UDP-MurNAc pentapeptide analogue 1 was found to be incorporated into the bacterial cell wall through biosynthesis. Compound 2 showed growth-inhibition activity against Gram-positive bacteria when it was added to growth media at 0.01 mg/mL. [structure--see text] 相似文献
74.
75.
76.
Carbon hollow spheres (400-600 nm) and vessels (400 nm x 3000 nm) have been synthesized from sp3-CCl4 at 190 and 230 degrees C, respectively. The HRTEM images and Raman spectra reveal the sp2 nature of the as-obtained products, indicating that the transformation from carbon sp3 to sp2 occurs in the reactions. The possible mechanism has also been proposed. 相似文献
77.
The complexation of lanthanide(III) cations with 1,2-propanediaminetetraacetate (1,2-PDTA) in aqueous solution has been investigated by 10Na, 35Cl, 2H and 11O NMR shift measurements. It has been shown that the contact shifts are dominant for 17O, 16Cl and 2H (only for the heavier lanthanide series) and the pseudocontact shifts are dominant for 25Na. It is suggested that the 1,2-PDTA ligand is bound pentadentately via the two nitrogens and the three carboxylates for the lighter lanthanide complexes, hexdentately via the two nitrogens and the four carboxylates for the heavier ones. The numbers of the water coordinated were determined. The small amount of chloride anion in inner coordination sphere was observed. 相似文献
78.
79.
Polycrystal Li2B4O7 (LBO) doped with Cu and In was prepared and then sintered at different temperatures. X-ray diffraction (XRD) was applied
to get the parameters of the LBO structure, thermoluminescence (TL) and optically stimulated luminescence (OSL) were measured,
and a second-order exponential decay model was fitted to the OSL decay curves. The results indicate that the original number
of OSL traps that have captured electroncs is linearly related with the sum of TL decay during the OSL process. Mean decay
constant of OSL is related to the sintered temperature. The possible reason is that the sintered temperature affects the crystal
sizes of the polycrystal, and consequently affects the stimulating lights’s intensity and the photoionization cross-section
of the electrons, which have been captured by the traps.
__________
Translated from Acta Scientiarum Naturalium Universitatis Sunyatseni, 2005, 44(4) (in Chinese) 相似文献
80.
高密度燃料HDF-1与橡胶的相容性研究 总被引:3,自引:0,他引:3
报道了在室温和70 ℃下橡胶材料G402氟硅胶、丁腈胶5171、丁腈胶4170、贮囊橡胶用合成的高密度燃料HDF-1浸泡后性能如伸长率、邵尔硬度、重量、面积体积的变化,并与采用3号喷气燃料(RP-3)实验结果进行对照。用红外光谱测定了燃料浸泡前后橡胶组成的变化。实验结果表明,G402氟硅胶和贮囊对于HDF-1和RP-3有相近的相容性,丁腈胶5171对HDF-1的相容性比对RP-3的相容性稍差,丁腈胶4170对HDF-1的相容性比对RP-3的相容性更差的结果。因此,丁腈胶5171和丁腈胶4170不能用于HDF-1储存和输送,原使用RP-3系统的橡胶密封件不能直接使用HDF-1。 相似文献