全文获取类型
收费全文 | 109375篇 |
免费 | 863篇 |
国内免费 | 580篇 |
专业分类
化学 | 40303篇 |
晶体学 | 1231篇 |
力学 | 8031篇 |
综合类 | 11篇 |
数学 | 36117篇 |
物理学 | 25125篇 |
出版年
2023年 | 71篇 |
2022年 | 427篇 |
2021年 | 762篇 |
2020年 | 812篇 |
2019年 | 1005篇 |
2018年 | 11638篇 |
2017年 | 11472篇 |
2016年 | 7839篇 |
2015年 | 1772篇 |
2014年 | 1980篇 |
2013年 | 3076篇 |
2012年 | 5983篇 |
2011年 | 12550篇 |
2010年 | 7781篇 |
2009年 | 8107篇 |
2008年 | 8612篇 |
2007年 | 10611篇 |
2006年 | 1864篇 |
2005年 | 2371篇 |
2004年 | 2280篇 |
2003年 | 2405篇 |
2002年 | 1431篇 |
2001年 | 588篇 |
2000年 | 926篇 |
1999年 | 535篇 |
1998年 | 660篇 |
1997年 | 590篇 |
1996年 | 330篇 |
1995年 | 163篇 |
1994年 | 116篇 |
1993年 | 110篇 |
1992年 | 84篇 |
1991年 | 84篇 |
1990年 | 75篇 |
1989年 | 74篇 |
1988年 | 70篇 |
1987年 | 81篇 |
1986年 | 69篇 |
1985年 | 65篇 |
1984年 | 61篇 |
1983年 | 51篇 |
1982年 | 63篇 |
1981年 | 51篇 |
1980年 | 65篇 |
1979年 | 52篇 |
1978年 | 45篇 |
1914年 | 45篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 643 毫秒
31.
Caesium carbonate supported on hydroxyapatite‐encapsulated Ni0.5Zn0.5Fe2O4 nanocrystallites as a novel magnetically basic catalyst for the one‐pot synthesis of pyrazolo[1,2‐b]phthalazine‐5,10‐diones
下载免费PDF全文
![点击此处可从《应用有机金属化学》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Behrooz Maleki Samaneh Barat Nam Chalaki Samaneh Sedigh Ashrafi Esmail Rezaee Seresht Farid Moeinpour Amir Khojastehnezhad Reza Tayebee 《应用有机金属化学》2015,29(5):290-295
A novel nanomagnetic basic catalyst of caesium carbonate supported on hydroxyapatite‐coated Ni0.5Zn0.5Fe2O4 magnetic nanoparticles (Ni0.5Zn0.5Fe2O4@HAP‐Cs2CO3) was prepared. This new catalyst was fully characterized using Fourier transform infrared spectroscopy, transmission and scanning electron microscopy, X‐ray diffraction and vibrating sample magnetometry techniques, and then the catalytic activity of this catalyst was investigated in the synthesis of 1H‐pyrazolo[1,2‐b]phthalazine‐5,10‐dione derivatives. Also, Ni0.5Zn0.5Fe2O4@HAP‐Cs2CO3 could be reused at least five times without significant loss of activity and could be recovered easily by applying an external magnet. Thus, the developed nanomagnetic catalyst is potentially useful for the green and economic production of organic compounds. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
32.
33.
34.
35.
36.
37.
Efficacy of incorporating PCMs into the commercial wall on the energy-saving annual thermal analysis
Nguyen Quyen Naghieh Alireza Kalbasi Rasool Akbari Mohammad Karimipour Arash Tlili Iskander 《Journal of Thermal Analysis and Calorimetry》2021,143(3):2179-2187
Journal of Thermal Analysis and Calorimetry - In this study, the efficacy of incorporating phase change material (PCM) into the building walls on the annual heat transfer reduction is examined.... 相似文献
38.
Rashidi Saman Hormozi Faramarz Sarafraz Mohammad Mohsen 《Journal of Thermal Analysis and Calorimetry》2021,143(3):1833-1854
Journal of Thermal Analysis and Calorimetry - Boiling process is a highly efficient mechanism of heat transfer, which has an important role in industrial and domestic sectors. In this process, a... 相似文献
39.
Rachida M’chaar Abdelaziz Sabbar Mouloud El Moudane Noureddine Ouerfelli 《哲学杂志》2020,100(11):1415-1438
ABSTRACT By applying the geometric models and the theoretical equation, the surface tension, the molar volume and the density were studied. The empirical calculations were carried out in temperature range 623?K?≤?T?≤?1123?K. Only few thermophysical properties were estimated for eight quinary alloys: Sn3.55Ag0.5Cu3Bi3Sb, Sn3.48Ag0.5Cu3Bi5Sb, Sn3.48 Ag0.5Cu5Bi3Sb, Sn3.40 Ag0.5Cu5Bi5Sb, Sn3.53Ag1Cu3Bi3Sb, Sn3.46Ag1Cu3Bi5Sb, Sn3.46Ag1Cu5Bi3Sb, Sn3.38Ag1Cu5Bi5Sb. The results show that surface tension and density have a linear appearance for all temperatures. We have also studied the influence of the composition and temperature in the studied alloys. The obtained theoretical results are compared with the experimental ones and with the conventional Pb–Sn welds. 相似文献
40.