全文获取类型
收费全文 | 1071篇 |
免费 | 62篇 |
国内免费 | 15篇 |
专业分类
化学 | 720篇 |
晶体学 | 6篇 |
力学 | 41篇 |
数学 | 122篇 |
物理学 | 259篇 |
出版年
2024年 | 9篇 |
2023年 | 20篇 |
2022年 | 127篇 |
2021年 | 101篇 |
2020年 | 43篇 |
2019年 | 52篇 |
2018年 | 54篇 |
2017年 | 36篇 |
2016年 | 82篇 |
2015年 | 63篇 |
2014年 | 77篇 |
2013年 | 74篇 |
2012年 | 84篇 |
2011年 | 60篇 |
2010年 | 36篇 |
2009年 | 27篇 |
2008年 | 34篇 |
2007年 | 26篇 |
2006年 | 24篇 |
2005年 | 18篇 |
2004年 | 12篇 |
2003年 | 8篇 |
2002年 | 12篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 7篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1976年 | 2篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1965年 | 2篇 |
排序方式: 共有1148条查询结果,搜索用时 15 毫秒
121.
Waseem Sharaf Saeed Hamad Abdullah Al-Lohedan Abdel-Basit Mohammed Al-Odayni Abdulaziz Ali Alghamdi Ahmad Abdulaziz Al-Owais 《Journal of Dispersion Science and Technology》2019,40(1):128-139
An n-butyl bromide/sodium dodecyl sulfate/n-butanol/water microemulsion system was chosen as a model of an organohalide-containing microemulsion. Two systems were prepared using the Bourayne method: a water-rich system and an n-butyl-bromide-rich system. The destabilization of this micro-organized system and the phase separation were investigated. This microemulsion, in which the oil phase in the feed is the lower layer, was successfully destabilized using the pervaporation technique with polydimethylsiloxane and poly(vinyl alcohol) membranes. In this way, different factors governing the separation process were investigated such as the mass transfer and the effect of time and operating temperature on the microemulsion destabilization. 相似文献
122.
Boubakri L. Al-Ayed Abdullah S. Mansour L. Harrath A. A. Al-Tamimi J. Özdemir I. Yasar S. Hamdi N. 《Transition Metal Chemistry》2019,44(4):321-328
Transition Metal Chemistry - The carbonylative Suzuki cross-coupling of 2-bromopyridine with various boronic acids to prepare unsymmetrical arylpyridine ketones has been carried out using... 相似文献
123.
Mahmoud M. Sebaiy Abdullah A. El‐Shanawany Mohamed M. Baraka Lobna M. Abdel‐Aziz 《中国化学会会志》2019,66(2):179-187
This article presents a continuous capillary electrophoresis with laser‐induced fluorescence (CE‐LIF) following spectral studies of the noncovalent interactions between novel Squarylium Boronic Acid 4 (SQ‐BA4) & Squarylium Diboronic Acid 2 (SQ‐DBA2) squarylium dyes and human serum albumin (HSA). Two protocols were used wherein the on‐column‐labeling protocol was found to be more sensitive than the precolumn one by showing a better enhancement in the peak area of the HSA–dye complex besides lower limits of detection (LODs) for HSA. Also, stability studies were conducted with or without HSA using precolumn‐labeling mode over one week exhibiting the superiority of SQ‐BA4 to SQ‐DBA2. Then, a mixture containing three model proteins, HSA, β‐lactoglobulin B, and transferrin, was labeled on‐column with both dyes and completely resolved by CE‐LIF after optimization of several parameters. Both dyes provided lower LODs for HSA than those of β‐lactoglobulin B and transferrin with higher sensitivities. In addition, the SQ‐BA4 dye showed again greater sensitivities with all the three proteins than SQ‐DBA2. 相似文献
124.
Nonlinear wave propagation is studied theoretically in a one-dimensional photonic band gap structure containing single negative materials. It is found that Kerr nonlinearity is greatly enhanced near the lower edge of a recently explored angular gap for transverse magnetic polarized light. Consequently, optical bistability is achieved at very low values of input intensity in a periodic structure composed of only a few repeating units. The characteristics of optical bistability are affected only slightly with the variation of the incident angle and thickness ratio of the layers. The effect of losses is also found to be relatively insignificant in such a small structure. 相似文献
125.
Abdullah Aljaafari Ayman Al-Sawalha 《Journal of Physics and Chemistry of Solids》2008,69(11):2919-2923
The impact of Bi2O3 addition on the structural, microhardness (Vickers microhardness (VHN)), resistivity and Hall coefficient measurements of Bi3.4Pb0.3Sr2Ca1.3−x RExCu2Oy ceramic samples with various x and RE is investigated. X-ray diffraction results indicate that all the peaks belong to Bi: 2212 and 2201 phases. The moderate amount of 2212 phase exists as a major phase, while the 2201 phase as a minor. The net intensity of all peaks Imax for 2212 phase increases with Y as compared to undoped sample, followed by a gradual decrease with further increase in rare earth (RE) up to La. While the vice versa is recorded for both 2201 phase and VHN. Except Y sample, a good link between flake-type grains is observed in the SEM photographs of the considered samples. The electrical resistivity turns from quiet metallic for undoped sample to semiconducting behavior for all substituted samples without any transition to the superconducting state. The Hall coefficient sign is found to be positive for undoped and Y samples and it changed from positive to negative for the other RE-substituted samples. The possible reasons for superconductivity quenching by RE substitution in this type of ceramic materials are reported. 相似文献
126.
Properties of the angular gap in a one-dimensional photonic band gap structure containing single negative materials are investigated. This gap forms at oblique incidence due to the total internal reflection into air when the Snell's law breaks down. Its lower edge occurs at the frequency where the refractive index of one or both layers of the structure approaches zero. This gap is found to be highly sensitive to the incident angle and the polarization of the incident light, but is not affected by the thickness ratio of the layers. It is also shown that the electric field gets extremely enhanced at the lower edge of this gap for transverse magnetic polarization. This highly enhanced electric field can be utilized for certain applications. 相似文献
127.
Ye Jingyao Al-Jobory Alaa Zhang Qian-Chong Cao Wenqiang Alshehab Abdullah Qu Kai Alotaibi Turki Chen Hang Liu Junyang Ismael Ali K. Chen Zhong-Ning Lambert Colin J. Hong Wenjing 《中国科学:化学(英文版)》2022,65(9):1822-1828
Science China Chemistry - Destructive quantum interference (DQI) provides a unique approach to controlling the leakage current in the OFF state of molecular devices. However, the DQI in... 相似文献
128.
Akyuz Sevim Celik Sefa Usta Abdullah Taner Ozel Aysen E. Yılmaz Gözde Yılmaz Salih 《Optics and Spectroscopy》2020,128(8):1318-1327
Optics and Spectroscopy - Endometriosis is a benign gynecologic disorder. It is particularly common among young women and may make pregnancy difficult. In this study molecular level... 相似文献
129.
130.