全文获取类型
收费全文 | 1006篇 |
免费 | 180篇 |
国内免费 | 100篇 |
专业分类
化学 | 695篇 |
晶体学 | 5篇 |
力学 | 85篇 |
综合类 | 2篇 |
数学 | 82篇 |
物理学 | 417篇 |
出版年
2023年 | 21篇 |
2022年 | 15篇 |
2021年 | 26篇 |
2020年 | 37篇 |
2019年 | 52篇 |
2018年 | 30篇 |
2017年 | 24篇 |
2016年 | 48篇 |
2015年 | 40篇 |
2014年 | 37篇 |
2013年 | 66篇 |
2012年 | 107篇 |
2011年 | 115篇 |
2010年 | 74篇 |
2009年 | 61篇 |
2008年 | 64篇 |
2007年 | 48篇 |
2006年 | 45篇 |
2005年 | 38篇 |
2004年 | 45篇 |
2003年 | 22篇 |
2002年 | 22篇 |
2001年 | 20篇 |
2000年 | 27篇 |
1999年 | 30篇 |
1998年 | 23篇 |
1997年 | 16篇 |
1996年 | 26篇 |
1995年 | 21篇 |
1994年 | 9篇 |
1993年 | 14篇 |
1992年 | 10篇 |
1991年 | 12篇 |
1990年 | 12篇 |
1989年 | 6篇 |
1988年 | 1篇 |
1987年 | 7篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有1286条查询结果,搜索用时 15 毫秒
51.
Dr. Gui‐Chao Kuang Ming‐Jun Teng Prof. Xin‐Ru Jia Prof. Dr. Er‐Qiang Chen Prof. Dr. Yen Wei 《化学:亚洲杂志》2011,6(5):1163-1170
There is a delicate balance for a low‐weight molecule to behave as a gelator or crystal. The synthesis of two novel amino acid‐based naphthalene‐dendrons, Nap ‐ G1 and Nap ‐ G2 is described. Both dendrons display polymorphic properties in organic solvents. Nap ‐ G1 developed a fibrous network with β‐sheet architecture in cyclohexane but exhibited a spherulitic network in mixed solvents (chloroform/petroleum ether 1:5, v/v). On the other hand, Nap ‐ G2 acted as an efficient organogelator in chloroform but formed crystalline fibers in relatively high polarity solvents (such as acetone and methanol). Combinations of characterizations have been employed to study the polymorphism. 相似文献
52.
53.
Kuang Jichang 《逼近论及其应用》1999,15(1):83-91
The HK
q
a,p
(w1,w2) and HK
q
a,p
(w1, w2) boundedness of C-Z type singular integral operators are proved. 相似文献
54.
R. Bernabei P. Belli F. Montecchia W. Di Nicolantonio G. Ignesti A. Incicchitti D. Prosperi C. J. Dai L. K. Ding H. H. Kuang J. M. Ma 《Physics letters. [Part B]》1999,450(4):40
The results achieved with a statistics of 14962 kg·day, collected with the large mass highly radiopure DAMA NaI(Tl) set-up, are described and investigated in terms of WIMP annual modulation signature. A maximum likelihood analysis of these data, combined with the statistics of 4549 kg·day previously published (total statistics of 19511 kg·day), favours the hypothesis of presence of an annual modulation at 99.6% C.L. 相似文献
55.
Liu Haiqing Wang Xiangwei Kuang Chunxia Li Lei Zhai Yunyun 《Journal of Solid State Electrochemistry》2018,22(11):3579-3587
Journal of Solid State Electrochemistry - Ionic conductivity is an important separator parameter influencing the cycle life and rate capability of lithium-ion batteries (LIBs). To improve the ionic... 相似文献
56.
57.
58.
Yan Li Xinru Jia Min Gao Hai He Guichao Kuang Yen Wei 《Journal of polymer science. Part A, Polymer chemistry》2010,48(3):551-557
Gn (n = 3, 4, and 5) poly(amidoamine) (PAMAM) dendrimers were synthesized and peripherally modified with photocleavable o‐nitrobenzyl (NB) groups by reacting o‐nitrobenzaldehyde with the terminal amine groups of PAMAM dendrimers, followed by reducing the imine to amine groups with NaBH4. The NB‐modified dendrimers, Gn‐NB (n = 3, 4, and 5), were characterized by nuclear magnetic resonance and fourier transform infrared spectroscopy. The results showed that the NB groups were successfully attached on the periphery of the dendrimers with near 100% grafting efficiency. Such a photosensitive NB shell could be cut off on irradiation with 365 nm ultraviolet (UV) light. The encapsulation and release of guest molecules, that is, salicylic acid (SA) and adriamycin (ADR), by Gn‐NB were explored. The encapsulation capability of these dendrimers was found to increase as the guest molecular size was decreased and have dependence on the generation of dendrimers as well. For both of SA and ADR, the average encapsulation numbers per dendrimer decreased in the order of G4‐NB > G5‐NB > G3‐NB, indicating that the fourth generation dendrimer was a better container for the guest molecules. The rate of SA release was found to be greater with UV irradiation than that without, suggesting that the NB‐shelled PAMMAM dendrimers could function as a molecular container/box with photoresponsive characteristics. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 551–557, 2010 相似文献
59.
Yi Yu Xiurong Zhu Xianke Zhang Jujun Yuan Huajun Yu Fangguang Kuang Zuzhou Xiong Jianfei Liao Wen Zhang Guofu Wang 《Optical Review》2016,23(3):391-400
A Pr3+:KLu(WO4)2 crystal with dimension of 30 × 30 × 15 mm3 was grown in the K2W2O7 flux. A slice was cut from the crystal, and the polarized absorption and fluorescence spectra were measured at room temperature. Based on the J-O theory, the oscillator intensity parameters Ω t (t = 2, 4, 6), spontaneous emission probabilities and branch ratios were estimated and good results had been obtained. Furthermore, the crystal has a relatively large emission cross-section in the region of 615–630 nm with the highest value of 14.5 × 10?20 cm2, which indicates that the crystal is good for the application in red emission laser. The emission decay time for 1D2 and 3P0 multiplets was discussed. By adapting the I-H model to fit the emission decay curves, the lifetime for 1D2 at 607 nm and 3P0 at 615 nm are 19.72 μs and 8.95 μs, respectively. Then the corresponding fluorescence quantum efficiencies of the two multiplets reach 83.7 % and 87.9 %, respectively. All the studies illustrate that this crystal is potential in red emission laser application. 相似文献
60.
Novel composite carbon particles are developed that can self‐assemble as a coating on a substrate without a binder. These carbon particles were used as a coating to enhance thermal dissipation and their thermal conductivity, surface emissivity and cooling performance were measured. Carbon particles with both thiol and epoxy functional groups self‐assembled to form a coating on the surface of a heat sink without a binder, which greatly improved the thermal conductivity of the coating. Coating a heat sink with the carbon particles yielded a higher thermal conductivity and emissivity than could be obtained with the addition of binder in the conventional approach, and significantly enhanced the cooling performance. In addition, the cooling performance of the carbon nanotube outperformed all other particles when coated on a substrate, because it had the highest thermal conductivity and good radiation emissivity. We developed an equation to describe the various parameters affecting the cooling performance of the thermally dissipative coating. This equation was confirmed by the experimental data. 相似文献