全文获取类型
收费全文 | 5683篇 |
免费 | 349篇 |
国内免费 | 33篇 |
专业分类
化学 | 3900篇 |
晶体学 | 94篇 |
力学 | 191篇 |
数学 | 868篇 |
物理学 | 1012篇 |
出版年
2023年 | 35篇 |
2022年 | 118篇 |
2021年 | 177篇 |
2020年 | 117篇 |
2019年 | 216篇 |
2018年 | 174篇 |
2017年 | 127篇 |
2016年 | 278篇 |
2015年 | 188篇 |
2014年 | 297篇 |
2013年 | 557篇 |
2012年 | 330篇 |
2011年 | 345篇 |
2010年 | 245篇 |
2009年 | 235篇 |
2008年 | 255篇 |
2007年 | 234篇 |
2006年 | 228篇 |
2005年 | 182篇 |
2004年 | 170篇 |
2003年 | 142篇 |
2002年 | 187篇 |
2001年 | 90篇 |
2000年 | 123篇 |
1999年 | 76篇 |
1998年 | 53篇 |
1997年 | 54篇 |
1996年 | 46篇 |
1995年 | 57篇 |
1994年 | 44篇 |
1993年 | 43篇 |
1992年 | 44篇 |
1991年 | 32篇 |
1990年 | 22篇 |
1989年 | 37篇 |
1988年 | 34篇 |
1987年 | 24篇 |
1986年 | 21篇 |
1985年 | 44篇 |
1984年 | 42篇 |
1983年 | 30篇 |
1982年 | 31篇 |
1981年 | 36篇 |
1980年 | 29篇 |
1979年 | 22篇 |
1978年 | 24篇 |
1977年 | 17篇 |
1976年 | 22篇 |
1975年 | 20篇 |
1973年 | 12篇 |
排序方式: 共有6065条查询结果,搜索用时 93 毫秒
961.
Quezada E Delogu G Viña D Santana L Picciau C Podda G Uriarte E 《Magnetic resonance in chemistry : MRC》2008,46(7):701-705
The synthesis of four pyranocoumarins starting from phloroglucinol and the complete (1)H and (13)C NMR assignment of seven pyranocoumarins has been performed using 1D and 2D NMR techniques including COSY, HMQC and HMBC experiments. 相似文献
962.
963.
1‐Morpholin‐4‐yl‐5,6,7,8‐tetrahydroisoquinoline‐4‐carbonitrile ( 2 ) was synthesized from 3‐amino‐1‐thioxo‐5,6,7,8‐tetrahydro‐1H‐isothiochromene‐4‐carbonitrile ( 1 ) and used as starting material to synthesize many thienotetrahydroisoquinolines ( 4 ), which in turn were used in the synthesis of many pyrimidothienotetrahydroisoquinolines. 相似文献
964.
Shen J El Ojaimi M Chkounda M Gros CP Barbe JM Shao J Guilard R Kadish KM 《Inorganic chemistry》2008,47(17):7717-7727
A series of manganese(III) corroles were investigated as to their electrochemistry and spectroelectrochemistry in nonaqueous solvents. Up to three oxidations and one reduction were obtained for each complex depending on the solvents. The main compound discussed in this paper is the meso-substituted manganese corrole, (Mes 2PhCor)Mn, and the main points are how changes in axially coordinated anion and solvent will affect the redox potentials and UV-vis spectra of each electrogenerated species in oxidation states of Mn(III), Mn(IV), or Mn(II). The anions OAc (-), Cl (-), CN (-), and SCN (-) were found to form five-coordinate complexes with the neutral Mn(III) corrole while two OH (-) or F (-) anions were shown to bind axially in a stepwise addition to give the five- and six-coordinate complexes in nonaqueous media. In each case, complexation with one or two anionic axial ligands led to an easier oxidation and a harder reduction as compared to the uncomplexed four-coordinate species. 相似文献
965.
Thakurta S Chakraborty J Rosair G Tercero J El Fallah MS Garribba E Mitra S 《Inorganic chemistry》2008,47(14):6227-6235
Two new Cu(II) linear trinuclear Schiff base complexes, [Cu3(L)2(CH3COO)2] (1) and [Cu3(L)2(CF3COO)2] (2), have been prepared using a symmetrical Schiff base ligand H2L [where H2L = N,N'-bis(2-hydroxyacetophenone)propylenediimine]. Both of the complexes have been characterized by elemental analyses, Fourier transform IR, UV/vis, and electron paramagnetic resonance spectroscopy. Single-crystal X-ray structures show that the adjacent Cu(II) ions are linked by double phenoxo bridges and a mu(2)-eta(1):eta(1) carboxylato bridge. In each complex, the central copper atom is located in an inversion center with distorted octahedral coordination geometry, while the terminal copper atoms have square-pyramidal geometry. Cryomagnetic susceptibility measurements over a wide range of temperature exhibit a distinct antiferromagnetic interaction of J = -36.5 and -72.3 cm(-1) for 1 and 2, respectively. Density functional theory calculations (B3LYP functional) and continuous-shape measurement (CShM) studies have been performed on the trinuclear unit to provide a qualitative theoretical interpretation of the antiferromagnetic behavior shown by the complexes. 相似文献
966.
Coronado E Galán-Mascarós JR Martí-Gastaldo C Ribera A Palacios E Castro M Burriel R 《Inorganic chemistry》2008,47(19):9103-9110
Layered double hydroxides containing paramagnetic Ni (II) and diamagnetic/paramagnetic Al (III)/Fe (III) ions have been prepared and characterized. Ni 2Al(OH) 6(NO 3). nH 2O ( 1), Ni 2Fe(OH) 6(NO 3). nH 2O ( 2), Ni 2Fe(OH) 6(C 6H 8O 4) 0.5. nH 2O ( 3), and Ni 2Fe(OH) 6(C 10H 16O 4) 0.5. nH 2O ( 4) were prepared by coprecipitation at controlled pH as polycrystalline materials with the typical brucite-like structure, with alternating layers of hydroxide and the corresponding anions, which determine the interlayer separation. Magnetic studies show the appearance of spontaneous magnetization between 2 and 15 K for these compounds. Interestingly, the onset temperature for spontaneous magnetization follows a direct relationship with interlayer separation, since this is the only magnetic difference between compounds 2, 3, and 4. Magnetic and calorimetric data indicate that long-range magnetic ordering is not occurring in any of these materials, but rather a freezing of the magnetic system in 3D due to the magnetic disorder and competing intra- and interlayer interactions. Thus, these hydrotalcite-like magnetic materials can be regarded as spin glasses. 相似文献
967.
Discovery of a Highly Selective Glycogen Synthase Kinase‐3 Inhibitor (PF‐04802367) That Modulates Tau Phosphorylation in the Brain: Translation for PET Neuroimaging
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Prof. Dr. Steven H. Liang Dr. Jinshan Michael Chen Prof. Dr. Marc D. Normandin Dr. Jeanne S. Chang Dr. George C. Chang Dr. Christine K. Taylor Dr. Patrick Trapa Dr. Mark S. Plummer Dr. Kimberly S. Para Dr. Edward L. Conn Dr. Lori Lopresti‐Morrow Dr. Lorraine F. Lanyon Dr. James M. Cook Dr. Karl E. G. Richter Dr. Charlie E. Nolan Dr. Joel B. Schachter Dr. Fouad Janat Dr. Ye Che Dr. Veerabahu Shanmugasundaram Dr. Bruce A. Lefker Dr. Bradley E. Enerson Prof. Dr. Elijahu Livni Lu Wang Dr. Nicolas J. Guehl Dr. Debasis Patnaik Florence F. Wagner Prof. Dr. Roy Perlis Dr. Edward B. Holson Prof. Dr. Stephen J. Haggarty Prof. Dr. Georges El Fakhri Dr. Ravi G. Kurumbail Prof. Dr. Neil Vasdev 《Angewandte Chemie (International ed. in English)》2016,55(33):9601-9605
Glycogen synthase kinase‐3 (GSK‐3) regulates multiple cellular processes in diabetes, oncology, and neurology. N‐(3‐(1H‐1,2,4‐triazol‐1‐yl)propyl)‐5‐(3‐chloro‐4‐methoxyphenyl)oxazole‐4‐carboxamide (PF‐04802367 or PF‐367) has been identified as a highly potent inhibitor, which is among the most selective antagonists of GSK‐3 to date. Its efficacy was demonstrated in modulation of tau phosphorylation in vitro and in vivo. Whereas the kinetics of PF‐367 binding in brain tissues are too fast for an effective therapeutic agent, the pharmacokinetic profile of PF‐367 is ideal for discovery of radiopharmaceuticals for GSK‐3 in the central nervous system. A 11C‐isotopologue of PF‐367 was synthesized and preliminary PET imaging studies in non‐human primates confirmed that we have overcome the two major obstacles for imaging GSK‐3, namely, reasonable brain permeability and displaceable binding. 相似文献
968.
Kamal El Fahri 《Quaestiones Mathematicae》2016,39(4):487-496
We investigate Banach lattices on which each positive almost Dunford- Pettis operator is almost limited and conversely. 相似文献
969.
970.