全文获取类型
收费全文 | 1367篇 |
免费 | 74篇 |
国内免费 | 19篇 |
专业分类
化学 | 840篇 |
晶体学 | 6篇 |
力学 | 15篇 |
数学 | 231篇 |
物理学 | 368篇 |
出版年
2023年 | 6篇 |
2022年 | 22篇 |
2021年 | 35篇 |
2020年 | 44篇 |
2019年 | 37篇 |
2018年 | 24篇 |
2017年 | 24篇 |
2016年 | 62篇 |
2015年 | 50篇 |
2014年 | 48篇 |
2013年 | 81篇 |
2012年 | 82篇 |
2011年 | 87篇 |
2010年 | 64篇 |
2009年 | 45篇 |
2008年 | 61篇 |
2007年 | 63篇 |
2006年 | 60篇 |
2005年 | 74篇 |
2004年 | 53篇 |
2003年 | 35篇 |
2002年 | 44篇 |
2001年 | 40篇 |
2000年 | 26篇 |
1999年 | 20篇 |
1998年 | 14篇 |
1997年 | 14篇 |
1996年 | 13篇 |
1995年 | 8篇 |
1994年 | 9篇 |
1993年 | 11篇 |
1992年 | 7篇 |
1990年 | 10篇 |
1989年 | 10篇 |
1987年 | 5篇 |
1985年 | 8篇 |
1984年 | 13篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 10篇 |
1980年 | 11篇 |
1979年 | 9篇 |
1978年 | 10篇 |
1976年 | 5篇 |
1975年 | 11篇 |
1974年 | 8篇 |
1973年 | 11篇 |
1971年 | 5篇 |
1970年 | 4篇 |
1968年 | 4篇 |
排序方式: 共有1460条查询结果,搜索用时 15 毫秒
101.
102.
103.
F. Mach P. Lederle A. Suchier W. R. Austin C. Ahrens W. E. Tischtschenko M. M. Raines K. Scharrer N. v. Bittera L. Dwoak Th. Dunkel N. Blome A. Travers Bauer K. Bamberg J. D'Ans F. Pohle W. Schuppe R. Dubrisay C. C. Howes C. B. Jacob und F. Scheffer 《Fresenius' Journal of Analytical Chemistry》1935,102(5-6):222-235
Ohne Zusammenfassung 相似文献
104.
W. Böttger K. Druschke A. Skrabal A. Scharrer R. Grundmann K. Polstorff K. Bülow K. Ahrens O. Mügge und H. G. Grimm 《Fresenius' Journal of Analytical Chemistry》1928,73(4):162-167
Ohne Zusammenfassung 相似文献
105.
106.
Reyes Malavé Osuna Rocio Ponce Ortiz Mari Carmen Ruiz Delgado Valentin G Nenajdenko Viktor V Sumerin Elizabeth S Balenkova Víctor Hernández Juan Teodomiro López Navarrete 《Chemphyschem》2007,8(5):745-750
Herein, we study the conjugation properties of three different thienoacenes, each of which has three or four fused thiophene rings, by means of Fourier transform Raman spectroscopy. The B3LYP/6-31G** vibrational analysis of all of the collected spectroscopic data evidences that the selective enhancement of a limited number of Raman scatterings is related to the occurrence in the three thienoacenes of a vibronic coupling between the lowest unoccupied frontier molecular orbital (LUMO) and some Raman-active skeletal nu(C==C) stretching modes of 1600-1300 cm(-1). 相似文献
107.
Yury Rodimkov Evgeny Efimenko Valentin Volokitin Elena Panova Alexey Polovinkin Iosif Meyerov Arkady Gonoskov 《Entropy (Basel, Switzerland)》2021,23(1)
When entering the phase of big data processing and statistical inferences in experimental physics, the efficient use of machine learning methods may require optimal data preprocessing methods and, in particular, optimal balance between details and noise. In experimental studies of strong-field quantum electrodynamics with intense lasers, this balance concerns data binning for the observed distributions of particles and photons. Here we analyze the aspect of binning with respect to different machine learning methods (Support Vector Machine (SVM), Gradient Boosting Trees (GBT), Fully-Connected Neural Network (FCNN), Convolutional Neural Network (CNN)) using numerical simulations that mimic expected properties of upcoming experiments. We see that binning can crucially affect the performance of SVM and GBT, and, to a less extent, FCNN and CNN. This can be interpreted as the latter methods being able to effectively learn the optimal binning, discarding unnecessary information. Nevertheless, given limited training sets, the results indicate that the efficiency can be increased by optimizing the binning scale along with other hyperparameters. We present specific measurements of accuracy that can be useful for planning of experiments in the specified research area. 相似文献
108.
109.
Synthesis and Structures of Gallium‐β‐Diketiminate Complexes: Isolation of a Dinuclear Gallium(II) Complex
下载免费PDF全文
![点击此处可从《无机化学与普通化学杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The sterically demanding β‐diketiminate ligand Ldmp [Ldmp = HC{(CMe)N(dmp)}2, dmp = C6H3‐2,6‐Me2] was used to stabilize various gallium complexes in the formal oxidation states +II and +III. The reaction of in situ generated [LdmpLi] with gallium chloride affords [LdmpGaCl2] ( 1 ), which was used as starting complex to synthesize a variety of gallium(III) compounds [LdmpGaX2] [X = F ( 2 ), I ( 3 ), H ( 4 ), and Me ( 5 )]. Synthesis of the dinuclear complex [LdmpGaI]2 ( 6 ), with gallium in the formal oxidation state +II was accomplished by converting “GaI” with in situ generated [LdmpLi] in toluene. All compounds were characterized by elemental analyses, NMR spectroscopy, LIFDI‐TOF‐MS, and single‐crystal X‐ray diffraction. Additionally DFT calculations were performed for analysis of the bonding in 6 . 相似文献
110.