全文获取类型
收费全文 | 390篇 |
免费 | 9篇 |
国内免费 | 2篇 |
专业分类
化学 | 240篇 |
力学 | 19篇 |
数学 | 38篇 |
物理学 | 104篇 |
出版年
2022年 | 4篇 |
2021年 | 18篇 |
2020年 | 14篇 |
2019年 | 20篇 |
2018年 | 20篇 |
2017年 | 15篇 |
2016年 | 13篇 |
2015年 | 16篇 |
2014年 | 22篇 |
2013年 | 64篇 |
2012年 | 34篇 |
2011年 | 32篇 |
2010年 | 16篇 |
2009年 | 16篇 |
2008年 | 17篇 |
2007年 | 14篇 |
2006年 | 6篇 |
2005年 | 7篇 |
2004年 | 10篇 |
2003年 | 7篇 |
2002年 | 9篇 |
2001年 | 8篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有401条查询结果,搜索用时 15 毫秒
21.
Millions of people around the world suffer from psychiatric illnesses, causing unbearable burden and immense distress to patients and their families. Accumulating evidence suggests that inflammation may contribute to the pathophysiology of psychiatric disorders such as major depression and bipolar disorder. Copious studies have consistently shown that patients with mood disorders have increased levels of plasma tumor necrosis factor (TNF)-α. Given these findings, selective anti-TNF-α compounds were tested as a potential therapeutic strategy for mood disorders. This mini-review summarizes the results of studies that examined the mood-modulating effects of anti-TNF-α drugs. 相似文献
22.
Mohammad Ali Zolfigol Ardeshir Khazaei Arash Ghorbani-Choghamarani Amin Rostami 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2453-2458
The regeneration of carbonyl compounds from oximes were performed by using silica chromate and wet SiO 2 (w/w 50%) under microwave irradiation and solvent-free conditions with excellent yields. 相似文献
23.
Manouchehr Mamaghani Abed Badrian 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2429-2435
The hydroxy group of the Baylis-Hillman adducts is protected with the t-butyldimethylsilyl (TBDMS) group using the reaction of adducts 1a–h with tert-butyldimethylsilyl chloride (TBDMSCl) in the presence of lithium sulfide under nearly acidic reaction conditions. 相似文献
24.
Abbas Shockravi Esmael Rostami Ali Dehjurian Rahim Tohidi Samad Bavili Tohidi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):535-541
Bis(dibenzosulfoxo)-27,30,35,38-tetramethyl-24-crown-6, bis(dibenzosulfoxo)-21,24,29,32-tetramethyl-18-crown-4, dibenzosulfoxo-15,18-dimethyl-12-crown-3 and dibenzosulfoxo-12,15-dimethyl-9-crown-2 macrocycles are synthesized by the reaction of 2,2′-sulfinyl-bis(4-methyl phenol)and 1,2-dibromoethane and diethyleneglycol di-p-toluenesulfonate. 相似文献
25.
Esmael Rostami Masume Zangooei Marziyh Ghaedi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):394-399
Abstract New aza thia crowns were prepared from the reaction of 2,2′-diaminodiphenyl disulfide and diacids or diacid chlorides. Diacids are malonic acid, adipic acid, sebacic acid, and 2,2′-thiodiacetic acid and diacid dichlorides are malonyl chloride, adipoyl chloride, sebacoyl chloride, and 2,2′-thiodiacetyl chloride. [Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional figures.] 相似文献
26.
Esmael Rostami 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):1853-1866
Abstract New dinaphthosulfoxide aza crowns were prepared from the corresponding dinaphthosulfoxide diester and diamines under reflux conditions (conventional heating) and microwave (MW) irradiation. These reaction routes were used for the synthesis of a series of aza crowns, such as dinaphthosulfide, dinaphthosulfone, dibenzosulfide, and dibenzosulfoxide. The synthesis of aza crowns under MW irradiation in comparison with conventional heating has several advantages, such as shorter reaction times, simpler reaction conditions, and the use of ecofriendly solvents, higher yields, and regioselectivity. In the MW synthesis, macrocyclization is preferred to oligomerization, and thus, the yields of byproducts are low. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. GRAPHICAL ABSTRACT 相似文献
27.
Esmael Rostami 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1694-1701
Abstract New dinaphthosulfide aza oxa thia crowns from 1-naphthol were prepared. At first, 2,2′-thiobis(1-hydroxynaphthalene) (a dinaphthol) was prepared from 1-naphthol. Then diester was prepared from the reaction of dinaphthol and methylchloroacetate. Aza crowns were synthesized from the reaction of diester and diamines (ethylene diamine, 1,3-diaminopropane, 1,4-diaminobutane, and 1,6-diaminohexane) in methanol. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. GRAPHICAL ABSTRACT 相似文献
28.
Abdullatif Azab Dorit Moradov Abed Al-Aziz Al-Quntar Morris Srebnik 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):937-943
Abstract Direct addition of organolithium to 1-alkynylphosphonates (1) afforded vinylphosphonates and enamine phosphonates (2) in good to excellent yields. The reaction was carried out in dry THF at low temperature and proved to be completely stereoselective (syn addition). Alkyl, aryl, and haloalkyl groups were attached to the alkynyl entity, so the resulting vinylphosphonates contained various functional groups. The stereochemistry of the products as well as mechanism of the reaction were determined based on 1H and 13C NMR. The synthesis of enamine phosphonates in the absence of complicated, highly expensive organometallic catalysis has not been previously reported. 相似文献
29.
Farid R. Zaggout Abed El‐Fattah A. Qaraman Shehata M. Zourab Hassan Abed Azzeez 《Journal of Dispersion Science and Technology》2013,34(7):1003-1007
This research involves the behavior of thymol phtalein pH indicator entrapped into the sol‐gel derived inorganic matrix. The method is based on the physical entrapment of the reagent molecules in the sol‐gel matrix. The immobilized thymol phthalein pH indicator shows behavior similar to its solution counterpart. The UV/vis spectra indicate that the thymol phthalein retains its structure during the sol‐gel reactions in terms of response to pH. Thymol phthalein can be regarded as uniformly distributed in the sol‐gel matrix. This observation has been confirmed using polarized microscopy. This research shows that thymol phtalein can be immobilized in sol‐gel glasses and used as a solid pH sensor. 相似文献
30.
Farid R. Zaggout Hassan Abed Elazzez Abed El Fattah A. Qaraman Issa El Nahal 《Journal of Dispersion Science and Technology》2013,34(4):561-565
This study involves the behavior of universal indicator entrapped into the sol‐gel matrix. The encapsulation of universal indicator has been prepared by acid catalyzed sol‐gel reaction of tetraethylorthosilicate (TEOS) in the presence of universal indicator to produce transparent monolithic silica doping with universal indicator. The immobilized universal indicator pH‐indicator shows behavior similar to its solution counterpart. The UV/VIS spectra indicate that the universal indicator retains its structure during the sol‐gel reactions in terms of response to pH. The universal indicator can be regarded as uniformly distributed in the sol‐gel matrix. The use of SDS surfactant has positive effects on the immobilized universal indicator monolithic disk due to homogenizing the polymerizing system. This observation has been confirmed using polarized microscopy. 相似文献