全文获取类型
收费全文 | 4737篇 |
免费 | 99篇 |
国内免费 | 12篇 |
专业分类
化学 | 2369篇 |
晶体学 | 89篇 |
力学 | 224篇 |
数学 | 663篇 |
物理学 | 1503篇 |
出版年
2022年 | 40篇 |
2021年 | 69篇 |
2020年 | 77篇 |
2019年 | 88篇 |
2018年 | 64篇 |
2017年 | 83篇 |
2016年 | 124篇 |
2015年 | 102篇 |
2014年 | 126篇 |
2013年 | 344篇 |
2012年 | 235篇 |
2011年 | 260篇 |
2010年 | 165篇 |
2009年 | 155篇 |
2008年 | 197篇 |
2007年 | 214篇 |
2006年 | 163篇 |
2005年 | 170篇 |
2004年 | 134篇 |
2003年 | 87篇 |
2002年 | 77篇 |
2001年 | 54篇 |
2000年 | 48篇 |
1999年 | 44篇 |
1998年 | 44篇 |
1996年 | 50篇 |
1995年 | 41篇 |
1994年 | 50篇 |
1993年 | 64篇 |
1992年 | 61篇 |
1991年 | 46篇 |
1990年 | 58篇 |
1989年 | 49篇 |
1988年 | 57篇 |
1987年 | 46篇 |
1986年 | 29篇 |
1985年 | 72篇 |
1984年 | 94篇 |
1983年 | 57篇 |
1982年 | 62篇 |
1981年 | 69篇 |
1980年 | 70篇 |
1979年 | 72篇 |
1978年 | 67篇 |
1977年 | 62篇 |
1976年 | 57篇 |
1975年 | 44篇 |
1974年 | 47篇 |
1973年 | 55篇 |
1972年 | 33篇 |
排序方式: 共有4848条查询结果,搜索用时 15 毫秒
1.
Walvekar Rashmi Zairin Danial Aminin Khalid Mohammad Mubarak Nabisab Mujawar TCSM Gupta 《Journal of Thermal Analysis and Calorimetry》2022,147(13):7193-7201
Journal of Thermal Analysis and Calorimetry - This study aims to investigate the thermal conductivity, viscosity and thermal degradation of naphthenic-based mineral oil, palm oil methyl ester... 相似文献
2.
Gupta M. Kulriya P. K. Kumar R. Ghumman S. S. 《Journal of Radioanalytical and Nuclear Chemistry》2020,323(3):1413-1418
Journal of Radioanalytical and Nuclear Chemistry - Zirconolite, a potential candidate for the immobilization of actinides was investigated for the induced effects of α-particles simulated... 相似文献
3.
Ajay Gupta Fillip Kumar Sarkar Rajib Sarkar Ramen Jamatia Chang Yeon Lee Gajendra Gupta Amarta Kumar Pal 《应用有机金属化学》2020,34(9):e5782
Magnetically retrieval CuFe2O4@MIL-101(Cr) metal–organic framework was successfully prepared from easily available starting materials and characterized using various spectroscopic and analytical techniques such as powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray, transmission electron microscopy, elemental mapping, Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller, vibrating sample magnetometer, and inductively coupled plasma optical emission spectroscopy. The catalyst was then used in the synthesis of benzodiazepines containing a triazole moiety in water. The advantages of this protocol include high yields, reusability of the catalyst, and gram-scale synthesis. 相似文献
4.
The heterostructured Ag nanoparticles decorated Fe3O4 Glutathione (Fe3O4‐Glu‐Ag) nanoparticles (NPs) were synthesized by sonicating glutathione (Glu) with magnetite and further surface immobilization of silver NPs on it. The ensuing magnetic nano catalyst is well characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), powder X‐ray diffraction (PXRD), thermogravimetric analysis (TGA). The prepared Fe3O4‐Glu‐Ag nanoparticles have proved to be an efficient and recyclable nanocatalyst with low catalyst loading for the reduction of nitroarenes and heteronitroarenes to respective amines in the presence of NaBH4 using water as a green solvent which could be easily separated at the end of a reaction using an external magnet and can be recycled up to 5 runs without any significant loss in catalytic activity. Gram scale study for the reduction of 4‐NP has also being carried out successfully and it has been observed that this method can serve as an efficient protocol for reduction of nitroarenes on industrial level. 相似文献
5.
Kielas-Jensen Calvin Cichella Venanzio Casbeer David Manyam Satyanarayana Gupta Weintraub Isaac 《Journal of Optimization Theory and Applications》2021,191(2-3):899-916
Journal of Optimization Theory and Applications - A framework for monitoring a target modeled as Dubins car using multiple UAVs is proposed. The UAVs are subject to minimum and maximum speed,... 相似文献
6.
Sharma Deepak Sharma Naresh Brahmbhatt D. I. Gupta Vivek K. 《Crystallography Reports》2019,64(7):1047-1050
Crystallography Reports - The crystal structure of the title compound is determined by single crystal X-ray structure analysis. The structure was solved by direct method and refined to a final... 相似文献
7.
Nonlinear Dynamics - We investigate the control of friction-induced vibration in a precision motion stage under the effect of the LuGre friction dynamics. We consider a lumped parameter model of... 相似文献
8.
9.
10.
Total Synthesis of the 7,10‐Epimer of the Proposed Structure of Amphidinolide N,Part II: Synthesis of C17–C29 Subunit and Completion of the Synthesis 下载免费PDF全文
Dr. Koji Ochiai Dr. Sankar Kuppusamy Yusuke Yasui Kenji Harada Dr. Nishant R. Gupta Dr. Yohei Takahashi Prof. Dr. Takaaki Kubota Prof. Dr. Jun'ichi Kobayashi Prof. Dr. Yujiro Hayashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(10):3287-3291
The total synthesis of 7,10‐epimer of the proposed structure of amphidinolide N was accomplished. The requisite chiral C17–C29 subunit was assembled stereoselectively via Keck allylation, Shi epoxidation, diastereoselective 1,3‐reduction, and a later oxidative synthesis of the THF framework. The C1–C13 and C17–C29 subunits were successfully coupled using a Enders RAMP “linchpin” as the C14–C16 three carbon unit, thereby controlling the chirality at C14 and C16. The labile allyl epoxy moiety was successfully constructed by Grieco–Nishizawa olefination at a final stage of the synthesis. 相似文献