全文获取类型
收费全文 | 6556篇 |
免费 | 150篇 |
国内免费 | 4篇 |
专业分类
化学 | 3790篇 |
晶体学 | 38篇 |
力学 | 129篇 |
数学 | 1413篇 |
物理学 | 1340篇 |
出版年
2023年 | 34篇 |
2021年 | 111篇 |
2020年 | 76篇 |
2019年 | 74篇 |
2018年 | 165篇 |
2017年 | 151篇 |
2016年 | 227篇 |
2015年 | 169篇 |
2014年 | 223篇 |
2013年 | 544篇 |
2012年 | 332篇 |
2011年 | 455篇 |
2010年 | 236篇 |
2009年 | 220篇 |
2008年 | 375篇 |
2007年 | 363篇 |
2006年 | 334篇 |
2005年 | 250篇 |
2004年 | 220篇 |
2003年 | 147篇 |
2002年 | 145篇 |
2001年 | 99篇 |
2000年 | 81篇 |
1999年 | 58篇 |
1998年 | 50篇 |
1997年 | 51篇 |
1996年 | 52篇 |
1995年 | 50篇 |
1993年 | 44篇 |
1992年 | 56篇 |
1991年 | 47篇 |
1990年 | 49篇 |
1989年 | 53篇 |
1988年 | 47篇 |
1987年 | 48篇 |
1986年 | 40篇 |
1985年 | 61篇 |
1984年 | 68篇 |
1983年 | 64篇 |
1982年 | 65篇 |
1981年 | 45篇 |
1980年 | 53篇 |
1979年 | 48篇 |
1978年 | 70篇 |
1977年 | 41篇 |
1976年 | 55篇 |
1975年 | 41篇 |
1974年 | 48篇 |
1973年 | 42篇 |
1972年 | 34篇 |
排序方式: 共有6710条查询结果,搜索用时 15 毫秒
1.
Majchrzak-Kucęba Izabela Ściubidło Aleksandra 《Journal of Thermal Analysis and Calorimetry》2019,138(6):4139-4144
Journal of Thermal Analysis and Calorimetry - The paper presents the effect of the tabletting pressure and time on the chemical structure and crystallinity of the CuBTC and MIL-53(Al)... 相似文献
2.
3.
4.
Redox‐Active Tetraruthenium Macrocycles Built from 1,4‐Divinylphenylene‐Bridged Diruthenium Complexes 下载免费PDF全文
Stefan Scheerer Dr. Michael Linseis Dr. Evelyn Wuttke Sabrina Weickert Prof. Dr. Malte Drescher Dr. Oliver Tröppner Prof. Dr. Ivana Ivanović‐Burmazović Andreas Irmler Prof. Dr. Fabian Pauly Prof. Dr. Rainer F. Winter 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(28):9574-9590
Metallamacrocylic tetraruthenium complexes were generated by treatment of 1,4‐divinylphenylene‐bridged diruthenium complexes with functionalized 1,3‐benzene dicarboxylic acids and characterized by HR ESI‐MS and multinuclear NMR spectroscopy. Every divinylphenylene diruthenium subunit is oxidized in two consecutive one‐electron steps with half‐wave potential splittings in the range of 250 to 330 mV. Additional, smaller redox‐splittings between the +/2+ and 0/+ and the 3+/4+ and 2+/3+ redox processes, corresponding to the first and the second oxidations of every divinylphenylene diruthenium entity, are due to electrostatic effects. The lack of electronic coupling through bond or through space is explained by the nodal properties of the relevant molecular orbitals and the lateral side‐by‐side arrangement of the divinylphenylene linkers. The polyelectrochromic behavior of the divinylphenylene diruthenium precursors is retained and even amplified in these metallamacrocyclic structures. EPR studies down to T=4 K indicate that the dications 1‐H2+ and 1‐OBu2+ are paramagnetic. The dications and the tetracation of macrocycle 3‐H display intense (dications) or weak ( 3‐H4+ ) EPR signals. Quantum chemical calculations indicate that the four most stable conformers of the macrocycles are largely devoid of strain. Bond parameters, energies as well as charge and spin density distributions of model macrocycle 5‐HMe were calculated for the different charge and spin states. 相似文献
5.
Snežana Jovanović Ralph Puchta Olivera Klisurić 《Journal of Coordination Chemistry》2016,69(5):735-747
The crystal structure of K[PtCl3(caffeine)] was determined. The coordination geometry around platinum is square-planar formed by N9 of the caffeine ligand and three Cl? ions. The bond lengths and angles of K[PtCl3(caffeine)] were compared with those reported for [PtCl3(caffeine)]? and K[PtCl3(theobromine)]. At the level of the statistical significance of the data we have compared, no differences in the bond distances and angles for any of these compounds were noticed. Weak interactions between K+ and Cl? are responsible for the formation of 1-D polymeric chains in the crystal structure of the complex. The interactions of K[PtCl3(caffeine)] with inosine (Ino) and guanosine-5′-monophosphate (5′-GMP) were studied by 1H NMR spectroscopy at 295 K in D2O in a molar ratio of 1 : 1. The results indicate formation of the reaction product [PtCl3(Nu)] (Nu=Ino or 5′-GMP) with the release of caffeine from the coordination sphere of the starting complex. The higher stability of the bond between the Pt(II) ion and Ino or 5′-GMP compared to the stability of the platinum–caffeine bond is confirmed by density functional theory calculations (B3LYP/LANL2DZp) using as models 9-methylhypoxanthine and 9-methylguanine. 相似文献
6.
7.
8.
9.
10.
Prof. Antonio Molinaro Prof. Otto Holst Dr. Flaviana Di Lorenzo Dr. Maire Callaghan Dr. Alessandra Nurisso Dr. Gerardino D'Errico Dr. Alla Zamyatina Prof. Francesco Peri Dr. Rita Berisio Prof. Roman Jerala Prof. Jesús Jiménez‐Barbero Dr. Alba Silipo Prof. Sonsoles Martín‐Santamaría 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(2):500-519
In many Gram‐negative bacteria, lipopolysaccharide (LPS) and its lipid A moiety are pivotal for bacterial survival. Depending on its structure, lipid A carries the toxic properties of the LPS and acts as a potent elicitor of the host innate immune system via the Toll‐like receptor 4/myeloid differentiation factor 2 (TLR4/MD‐2) receptor complex. It often causes a wide variety of biological effects ranging from a remarkable enhancement of the resistance to the infection to an uncontrolled and massive immune response resulting in sepsis and septic shock. Since the bioactivity of lipid A is strongly influenced by its primary structure, a broad range of chemical syntheses of lipid A derivatives have made an enormous contribution to the characterization of lipid A bioactivity, providing novel pharmacological targets for the development of new biomedical therapies. Here, we describe and discuss the chemical aspects regarding lipid A and its role in innate immunity, from the (bio)synthesis, isolation and characterization to the molecular recognition at the atomic level. 相似文献