全文获取类型
收费全文 | 8561篇 |
免费 | 659篇 |
国内免费 | 899篇 |
专业分类
化学 | 5563篇 |
晶体学 | 104篇 |
力学 | 162篇 |
综合类 | 32篇 |
数学 | 3639篇 |
物理学 | 619篇 |
出版年
2024年 | 4篇 |
2023年 | 40篇 |
2022年 | 90篇 |
2021年 | 208篇 |
2020年 | 284篇 |
2019年 | 386篇 |
2018年 | 376篇 |
2017年 | 204篇 |
2016年 | 290篇 |
2015年 | 302篇 |
2014年 | 463篇 |
2013年 | 616篇 |
2012年 | 686篇 |
2011年 | 682篇 |
2010年 | 570篇 |
2009年 | 650篇 |
2008年 | 655篇 |
2007年 | 709篇 |
2006年 | 563篇 |
2005年 | 378篇 |
2004年 | 392篇 |
2003年 | 324篇 |
2002年 | 171篇 |
2001年 | 98篇 |
2000年 | 97篇 |
1999年 | 130篇 |
1998年 | 90篇 |
1997年 | 81篇 |
1996年 | 80篇 |
1995年 | 60篇 |
1994年 | 69篇 |
1993年 | 59篇 |
1992年 | 60篇 |
1991年 | 33篇 |
1990年 | 27篇 |
1989年 | 21篇 |
1988年 | 36篇 |
1987年 | 24篇 |
1986年 | 24篇 |
1985年 | 23篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1977年 | 3篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Inside Cover: Bio‐Inspired Transition Metal–Organic Hydride Conjugates for Catalysis of Transfer Hydrogenation: Experiment and Theory (Chem. Eur. J. 7/2015) 下载免费PDF全文
32.
Dr. Luis M. Mori‐Quiroz Kirk W. Shimkin Dr. Sina Rezazadeh Ryan A. Kozlowski Prof. Dr. Donald A. Watson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(44):15654-15658
The oxidative copper‐catalyzed cross‐coupling of functionalized alkyl boronic esters with primary amides is reported. Through the identification of appropriate diketimine ligands, conditions for efficient coupling of both primary and secondary alkyl boronic esters with diverse primary amides, including acetamide, have been developed. 相似文献
33.
Sorin‐Claudiu Roşca Dr. Chiara Dinoi Dr. Elsa Caytan Dr. Vincent Dorcet Prof. Dr. Michel Etienne Prof. Dr. Jean‐François Carpentier Dr. Yann Sarazin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(19):6505-6509
Strontium and calcium (alkaline earth: Ae) olefin complexes stabilised by secondary Ae???F?C and β‐agostic Ae???H?Si interactions are presented. Olefin coordination onto the alkaline earths is plain in the solid state, and it is thermodynamically favoured over the coordination of THF. The existence of the Ae???olefin interactions is corroborated by solution NMR data and DFT computations. The coordination mode of the olefin varies with steric effects and, if enforced, olefin dissociation can be compensated by the other non‐covalent interactions, as supported by DFT computations. 相似文献
34.
Dr. Shang-Fu Yuan Wen-Di Liu Dr. Chun-Yu Liu Dr. Zong-Jie Guan Prof. Dr. Quan-Ming Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(24):e202104445
Surface organic ligands are critical in dictating the structures and properties of atomically precise metal nanoclusters. In contrast to the conventionally used thiolate, phosphine and alkynyl ligands, nitrogen donor ligands have not been used in the protection for well-defined metal nanoclusters until recently. This review focuses on recent developments in atomically precise metal nanoclusters stabilized by different types of nitrogen donor ligands, in which the synthesis, total structure determination and various properties are covered. We hope that this review will provide insights into the rational design of N donor-protected metal nanoclusters in terms of structural and functional modulation. 相似文献
35.
《Mendeleev Communications》2022,32(1):83-86
Gallium(III) catecholates with bipyridine ligand [(3,5-Cat)Ga(bipy)2]I and (3,6-Cat)GaI(bipy) (Cat is di-tert-butylcatecholate) were synthesized and characterized by single-crystal X-ray diffraction. The appearance of near-infrared ligand-to-ligand charge transfer for pentacoordinate complex was observed. 相似文献
36.
Dr. Huaiyuan Zhang Prof. Dr. Rodrigo A. Cormanich Prof. Dr. Thomas Wirth 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(5):e202103623
Several novel binaphthyl-based chiral hypervalent iodine(III) reagents have been prepared and structurally analysed. Various asymmetric oxidative reactions were applied to evaluate the reactivities and stereoselectivities of those reagents. Moderate to excellent yields were observed; however, very low stereoselectivities were obtained. NMR experiments indicated that these reagents are very easily hydrolysed in either chloroform or DMSO solvents leading to the limited stereoselectivities. It is concluded that the use of chiral ligands is an unsuccessful way to prepare efficient stereoselective iodine(III) reagents. 相似文献
37.
《Mendeleev Communications》2022,32(6):777-779
The reactions of aryllithium reagents o-LiC6H4CH2NR2 with (MeO)2CO afford two new tris(aryl)carbinols bearing pendant-NR2 donor groups in the side chain [o-R NCH C H ] COH [R = Me, R + R = (CH) ]. These alcohols feature helical chirality due to differently inclined aromatic fragments and are presented in a crystalline cell as two M and P enantiomers. Carbinol (R = Me) readily reacts with (Me3SiCH2)3Sc(THF)2 to give a scandium bis(alkyl) complex [(o-C6H4CH2NMe2)3CO]Sc(CH2SiMe3)2 featuring rigid binding of the alkoxy anion through a κ1-O, κ2-N chelating coordination mode 相似文献
38.
《Physics letters. A》2020,384(26):126677
The Ising-like model of spin-crossover solid compounds with quenched random ligand field has been investigated by the mean-field (infinite-range) approximation. An exact solution for the problem is found within the replica formalism. The magnetic diagrams are obtained; the relations between the intermolecular coupling and the temperature as well as the reentrant phenomena of the magnetic ordered phase are discussed. 相似文献
39.
40.
Masoumeh Ghasempour Alireza Iranbakhsh Mostafa Ebadi Zahra Oraghi Ardebili 《等离子体物理论文集》2020,60(4):e201900159
The plasma-primed seeds of Catharanthus roseus were cultured in a hormone-free culture medium under sterile conditions. Plasma of 30 or 60 s improved root length (mean = 41.4%) and biomass (mean = 47%), whereas plasma of 90 s delayed plant growth. The plasma treatments enhanced concentrations of photosynthetic pigments and soluble phenols. Plasma of 90 s increased the proline level. With a similar trend, plasma priming induced activities of phenylalanine ammonia-lyase, catalase (about twofold) and peroxidase (31%) enzymes. Plasma also upregulated the expressions of deacetylvindoline O-acetyltransferase gene by an average of 7.8 times. Similarly, the plasma-treated seedlings contained higher concentrations of alkaloids (mean = 72%). Here, molecular evidence is provided on the plasma-associated modifications in secondary metabolism. 相似文献