全文获取类型
收费全文 | 7743篇 |
免费 | 1735篇 |
国内免费 | 833篇 |
专业分类
化学 | 2811篇 |
晶体学 | 83篇 |
力学 | 129篇 |
综合类 | 74篇 |
数学 | 1081篇 |
物理学 | 2721篇 |
无线电 | 3412篇 |
出版年
2024年 | 33篇 |
2023年 | 122篇 |
2022年 | 193篇 |
2021年 | 214篇 |
2020年 | 221篇 |
2019年 | 208篇 |
2018年 | 189篇 |
2017年 | 302篇 |
2016年 | 312篇 |
2015年 | 286篇 |
2014年 | 501篇 |
2013年 | 852篇 |
2012年 | 623篇 |
2011年 | 589篇 |
2010年 | 497篇 |
2009年 | 502篇 |
2008年 | 584篇 |
2007年 | 581篇 |
2006年 | 555篇 |
2005年 | 497篇 |
2004年 | 411篇 |
2003年 | 375篇 |
2002年 | 359篇 |
2001年 | 202篇 |
2000年 | 207篇 |
1999年 | 148篇 |
1998年 | 88篇 |
1997年 | 102篇 |
1996年 | 82篇 |
1995年 | 85篇 |
1994年 | 79篇 |
1993年 | 52篇 |
1992年 | 45篇 |
1991年 | 36篇 |
1990年 | 24篇 |
1989年 | 31篇 |
1988年 | 12篇 |
1987年 | 14篇 |
1986年 | 18篇 |
1985年 | 15篇 |
1984年 | 11篇 |
1983年 | 3篇 |
1982年 | 16篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 4篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1974年 | 4篇 |
1973年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
311.
Davood Azarifar Behrooz Maleki Mehrnaz Setayeshnazar 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):2097-2102
An efficient and simple procedure has been developed for the synthesis of various 2-arylbenzothiazoles by acetic acid–promoted condensation of 2 -aminothiophenol with aromatic aldehydes under microwave irradiation and solvent-free conditions in high yields. 相似文献
312.
313.
Alireza Hasaninejad Khodabakhsh Niknam Abdolkarim Zare Ehsan Farsimadan Mohsen Shekouhy 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):147-155
Silphox [POCl3-n(SiO2)n] efficiently catalyzes the condensation of benzene-1,2-diamine with mono and dicarboxylic acids under microwave irradiation to afford benzimidazole derivatives in high yields and short reaction times. 相似文献
314.
Abdolkarim Zare Alireza Hasaninejad Mohammad Hassan Beyzavi Ahmad Reza Moosavi-Zare Ali Khalafi-Nezhad Mehrnoosh Roshankar 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1702-1712
KF/Al 2 O 3 efficiently catalyzes the microwave-assisted Michael addition of sulfonamides to α,β-unsaturated esters under solvent-free conditions to afford N-alkyl derivatives of sulfonamides as biologically interesting compounds in high yields and in short reaction times. In this reaction, N,N-dialkylsulfonamides are also produced, but in very low yields. 相似文献
315.
Majid M. Heravi Fereshteh Hydarzadeh Yahya Farhangi Mitra Ghassemzadeh 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1473-1475
Primary and secondary trimethylsilyl ethers are effeciently converted to the corresponding carbonyl compounds using HZSM-5 zeolite-supported CrO 3 under microwave irradiation in solventless system. 相似文献
316.
Hossein A. Oskooie Azam Ranjbaran Majid M. Heravi Mitra Ghassemzadeh 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):1711-1714
Reduction of aromatic nitro compounds to amine with hydroiodic acid was revisited. Under microwave irradiation on solid support the reduction proceeded efficiently and rapidly. 相似文献
317.
E. Karthikeyan S. Perumal S. Selvaraj 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2561-2567
A series of substituted 4,9a-diaryl-9,9a-dihydro-1H-[1,4]thiazino[4,3-a][1,3]benzimidazoles was prepared in good yields from the reaction of bis(aroylmethyl) sulfides with ortho-phenylenediamine in glacial acetic acid under reflux and under microwave irradiation. Microwave irradiation is found to accelerate the reaction, besides giving better yield in the case of the thiazinobenzimidazoles with electron-withdrawing groups in the aryl rings than the thermal reaction. 相似文献
318.
Abdollah Javidan A. R. Banan 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2253-2258
The synthesis of dialkyl-(2,2,2-trichloro-1-Hydroxyethyl) phosphonates using dialkyl hydrogen phosphite and chloral hydrate under solvent-free condition by microwave irradiation is reported. The products were chrachetrized using 1 H NMR, 13 C NMR, and 31 P NMR spectroscopy. 相似文献
319.
Jelem Restrepo José Salazar Simón E. López 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2311-2320
Abstract We describe a rapid and convenient methodology for the preparation of diverse 3-aryl and 3-trifluoromethyl 4H-1,2,4-benzothiadiazine-1,1-dioxides in a one-pot microwave-promoted reaction between 2-aminobenzenesulfonamides and benzaldehydes, trifluoroacetic acid or benzoic acids. GRAPHICAL ABSTRACT 相似文献
320.
Majid M. Heravi Hossein A. Oskooie Pegah Kazemian Fatemeh Drikvand Mitra Ghassemzadeh 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2341-2344
Cerium ammonium nitrate (CAN) adsorbed on HNO 3 /silica gel is a mild reagent for selective oxidation of benzylic alcohols to the corresponding aldehydes under microwave irradiation in solventless system. 相似文献