全文获取类型
收费全文 | 1414篇 |
免费 | 55篇 |
国内免费 | 46篇 |
专业分类
化学 | 1034篇 |
晶体学 | 9篇 |
力学 | 79篇 |
数学 | 119篇 |
物理学 | 274篇 |
出版年
2024年 | 2篇 |
2023年 | 8篇 |
2022年 | 42篇 |
2021年 | 45篇 |
2020年 | 59篇 |
2019年 | 60篇 |
2018年 | 82篇 |
2017年 | 51篇 |
2016年 | 83篇 |
2015年 | 66篇 |
2014年 | 89篇 |
2013年 | 208篇 |
2012年 | 96篇 |
2011年 | 93篇 |
2010年 | 73篇 |
2009年 | 66篇 |
2008年 | 75篇 |
2007年 | 66篇 |
2006年 | 43篇 |
2005年 | 27篇 |
2004年 | 26篇 |
2003年 | 12篇 |
2002年 | 29篇 |
2001年 | 15篇 |
2000年 | 13篇 |
1999年 | 15篇 |
1998年 | 11篇 |
1997年 | 7篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1978年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有1515条查询结果,搜索用时 0 毫秒
991.
Abdol R. Hajipour Majid Mostafavi Arnold E. Ruoho 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1920-1923
A green, straightforward, and novel method for oxidation of thiols to the corresponding disulfides is reported using K 2 S 2 O8 in the ionic liquid 1-butyl-3-methylimidazolium bromide [(bmim)Br] at 65–70°C. The corresponding disulfides were obtained in excellent yield and short reaction time. 相似文献
992.
Molecular Diversity - Layered double hydroxides (LDHs) are recognized as two-dimensional (2D) clay materials, which comprise the interlayer anions and host layers with a positive charge... 相似文献
993.
Mohammadi Majid Sedighi Mehdi Ghasemi Mostafa 《Research on Chemical Intermediates》2021,47(4):1377-1395
Research on Chemical Intermediates - The primary purpose of this study is to create a method for removal of nitrate and phosphate utilizing adsorption-based technique. To this end, the adsorption... 相似文献
994.
Majid Tafrihi Muhammad Imran Tabussam Tufail Tanweer Aslam Gondal Gianluca Caruso Somesh Sharma Ruchi Sharma Maria Atanassova Lyubomir Atanassov Patrick Valere Tsouh Fokou Raffaele Pezzani 《Molecules (Basel, Switzerland)》2021,26(4)
Medicinal plants and their derived compounds have drawn the attention of researchers due to their considerable impact on human health. Among medicinal plants, mint (Mentha species) exhibits multiple health beneficial properties, such as prevention from cancer development and anti-obesity, antimicrobial, anti-inflammatory, anti-diabetic, and cardioprotective effects, as a result of its antioxidant potential, combined with low toxicity and high efficacy. Mentha species are widely used in savory dishes, food, beverages, and confectionary products. Phytochemicals derived from mint also showed anticancer activity against different types of human cancers such as cervix, lung, breast and many others. Mint essential oils show a great cytotoxicity potential, by modulating MAPK and PI3k/Akt pathways; they also induce apoptosis, suppress invasion and migration potential of cancer cells lines along with cell cycle arrest, upregulation of Bax and p53 genes, modulation of TNF, IL-6, IFN-γ, IL-8, and induction of senescence phenotype. Essential oils from mint have also been found to exert antibacterial activities against Bacillus subtilis, Streptococcus aureus, Pseudomonas aeruginosa, and many others. The current review highlights the antimicrobial role of mint-derived compounds and essential oils with a special emphasis on anticancer activities, clinical data and adverse effects displayed by such versatile plants. 相似文献
995.
Rimadani Pratiwi Eka Noviana Rizky Fauziati Daniel Blascke Carro Firas Adinda Gandhi Mutiara Aini Majid Febrina Amelia Saputri 《Molecules (Basel, Switzerland)》2021,26(4)
Codeine is derived from morphine, an opioid analgesic, and has weaker analgesic and sedative effects than the parent molecule. This weak opioid is commonly used in combination with other drugs for over-the-counter cough relief medication. Due to the psychoactive properties of opioid drugs, the easily obtained codeine often becomes subject to misuse. Codeine misuse has emerged as a concerning public health issue due to its associated adverse effects such as headache, nausea, vomiting, and hemorrhage. Thus, it is very important to develop reliable analytical techniques to detect codeine for both quality control of pharmaceutical formulations and identifying drug misuse in the community. This review aims to provide critical outlooks on analytical methods applicable to the determination of codeine. 相似文献
996.
997.
Walaa F. Alsanie Abdulhakeem S. Alamri Osama Abdulaziz Magdi M. Salih Abdulwahab Alamri Syed Mohammed Basheeruddin Asdaq Mohammed Hisham Alhomrani Majid Alhomrani 《Molecules (Basel, Switzerland)》2022,27(17)
This study aimed to investigate the antidepressant property of crocin (Crocetin digentiobiose ester) using a chronic mild stress (CMS)-induced depression model in experimental mice. The tail suspension test (TST) and the sucrose preference test were used to evaluate the antidepressant effect on albino mice of either sex after three weeks of CMS. The period of immobility in the TST and percentage preference for sucrose solution were recorded. By monitoring brain malondialdehyde (MDA) level, catalase (CAT) activity, and reduced glutathione (GSH) level, the antioxidant potential was assessed. Three dosages of crocin (4.84, 9.69, and 19.38 mg/kg) were evaluated. When compared to controls, animals that received crocin administration during three periods of CMS had considerably shorter immobility times during the TST. Crocin treatment also raised the percentage preference for sucrose solution in a dose-dependent manner, bringing it to parity with the conventional antidepressant, imipramine. Animals that received a high dose of crocin had a much greater spontaneous locomotor activity. Furthermore, a high dose of crocin remarkably lowered plasma corticosterone and nitrite levels brought on by CMS. Additionally, high doses of crocin given during CMS greatly enhanced reduced glutathione levels while considerably reducing the brain’s MDA and catalase activities. In conclusion, high doses of crocin may have an antidepressant effect in an animal model through several mechanisms. However, further studies should be carried out to explore the role of neurotransmitters for their antidepressant property. 相似文献
998.
Rafaqat Hussain Hayat Ullah Fazal Rahim Maliha Sarfraz Muhammad Taha Rashid Iqbal Wajid Rehman Shoaib Khan Syed Adnan Ali Shah Sajjad Hyder Majid Alhomrani Abdulhakeem S. Alamri Osama Abdulaziz Mahmoud A. Abdelaziz 《Molecules (Basel, Switzerland)》2022,27(18)
Twenty-four analogues of benzimidazole-based thiazoles (1–24) were synthesized and assessed for their in vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory potential. All analogues were found to exhibit good inhibitory potential against cholinesterase enzymes, having IC50 values in the ranges of 0.10 ± 0.05 to 11.10 ± 0.30 µM (for AChE) and 0.20 ± 0.050 µM to 14.20 ± 0.10 µM (for BuChE) as compared to the standard drug Donepezil (IC50 = 2.16 ± 0.12 and 4.5 ± 0.11 µM, respectively). Among the series, analogues 16 and 21 were found to be the most potent inhibitors of AChE and BuChE enzymes. The number (s), types, electron-donating or -withdrawing effects and position of the substituent(s) on the both phenyl rings B & C were the primary determinants of the structure-activity relationship (SAR). In order to understand how the most active derivatives interact with the amino acids in the active site of the enzyme, molecular docking studies were conducted. The results obtained supported the experimental data. Additionally, the structures of all newly synthesized compounds were elucidated by using several spectroscopic methods like 13C-NMR, 1H-NMR and HR EIMS. 相似文献
999.
Eileen W.C. Cheng Reena T. Mandalia Majid Motevalli Begum Mothia Yashvant Patanwadia Peter B. Wyatt 《Tetrahedron》2006,62(52):12398-12407
Dienophiles of the general structure (EtO)2P(O)CHCHCOX have been prepared, where X represents an oxazolidinone chiral auxiliary. Use of the (S)-4-isopropyl-5,5-diphenyl-1,3-oxazolidin-2-one auxiliary gave Diels–Alder adducts with several cyclic and acyclic dienes. The crystal structures of the main cyclohexa-1,3-diene and 2,3-dimethylbutadiene adducts formed during reactions in the presence of dialkylaluminium halides are consistent with a reaction, which is stereoselectively endo with respect to the carbonyl group and occurs on the less hindered face of the dienophile when aluminium is chelated between the two carbonyl groups. 相似文献
1000.
Majid M. Heravi Hamideh Alinejhad Zohreh Daroogheha Fatemeh F. Bamoharram Fatemeh Derikvand 《合成通讯》2013,43(15):2191-2200
An efficient synthesis of indeno[1,2-b]quinoline-9,11(6H,10H)-dione derivatives was reported via four-component coupling reaction of aldehydes, dimedone, 1,3-indandione, and amines in refluxing ethanol or three-component condensation of aldehydes, 1,3-indandione, and 5,5-dimethyl-3-arylamino-cyclohex-2-enone derivatives at 120 °C under solvent-free conditions in the presence of a catalytic amount of Preyssler-type heteropolyacid, H14[NaP5W30O110], as a green and reusable catalyst. 相似文献