全文获取类型
收费全文 | 53788篇 |
免费 | 19994篇 |
国内免费 | 1356篇 |
专业分类
化学 | 62644篇 |
晶体学 | 213篇 |
力学 | 2684篇 |
综合类 | 112篇 |
数学 | 4006篇 |
物理学 | 5479篇 |
出版年
2024年 | 174篇 |
2023年 | 4265篇 |
2022年 | 1814篇 |
2021年 | 2933篇 |
2020年 | 5111篇 |
2019年 | 2824篇 |
2018年 | 2683篇 |
2017年 | 1002篇 |
2016年 | 6084篇 |
2015年 | 6049篇 |
2014年 | 5540篇 |
2013年 | 5943篇 |
2012年 | 4169篇 |
2011年 | 2080篇 |
2010年 | 4098篇 |
2009年 | 4018篇 |
2008年 | 1723篇 |
2007年 | 1375篇 |
2006年 | 651篇 |
2005年 | 563篇 |
2004年 | 461篇 |
2003年 | 396篇 |
2002年 | 339篇 |
2001年 | 294篇 |
2000年 | 218篇 |
1999年 | 276篇 |
1998年 | 227篇 |
1997年 | 258篇 |
1996年 | 256篇 |
1995年 | 292篇 |
1994年 | 201篇 |
1993年 | 287篇 |
1992年 | 168篇 |
1991年 | 144篇 |
1988年 | 155篇 |
1982年 | 137篇 |
1981年 | 164篇 |
1980年 | 207篇 |
1979年 | 186篇 |
1978年 | 193篇 |
1977年 | 310篇 |
1976年 | 368篇 |
1975年 | 459篇 |
1974年 | 473篇 |
1973年 | 286篇 |
1972年 | 371篇 |
1971年 | 357篇 |
1970年 | 542篇 |
1969年 | 413篇 |
1968年 | 442篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
951.
952.
953.
954.
John Bentley Dr. Salil Desai Dr. Bishnu Prasad Bastakoti 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(36):9241-9252
Tungsten oxide (WO3) has received ever more attention and has been highly researched over the last decade due to its being a low-cost transition metal semiconductor with tunable, yet widely stable, band gaps. This minireview briefly highlights the challenges in the design and synthesis of porous WO3 including methods, precursors, solvent effects, crystal phases, and surface activities of the porous WO3 base material. These topics are explored while also drawing a connection of how the morphology and crystal phase affect the band gap. The shifts in band gap not only impact the optical properties of tungsten but also allow tuning to operate on different energy levels, which makes WO3 highly desirable in many applications such as supercapacitors, batteries, solar cells, catalysts, sensors, smart windows, and bioapplications. 相似文献
955.
Zhenhui Qi Dr. Changzhu Wu Dr. Paula Malo de Molina Han Sun Andrea Schulz Prof. Christian Griesinger Prof. Michael Gradzielski Prof. Rainer Haag Prof. Marion B. Ansorge‐Schumacher Prof. Christoph A. Schalley 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(31):10150-10159
A new and versatile, crown ether appended, chiral supergelator has been designed and synthesized based on the bis‐urea motif. The introduction of a stereogenic center improved its gelation ability significantly relative to its achiral analogue. This low‐molecular‐weight gelator forms supramolecular gels in a variety of organic solvents. It is sensitive to multiple chemical stimuli and the sol–gel phase transitions can be reversibly triggered by host–guest interactions. The gel can be used to trap enzymes and release them on demand by chemical stimuli. It stabilizes the microparticles in Pickering emulsions so that enzyme‐catalyzed organic reactions can take place in the polar phase inside the microparticles, the organic reactants diffusing through the biphasic interface from the surrounding organic phase. Because of the higher interface area between the organic and polar phases, enzyme activity is enhanced in comparison with simple biphasic systems. 相似文献
956.
957.
Gadolinium‐Decorated Silica Microspheres as Redox‐Responsive MRI Probes for Applications in Cell Therapy Follow‐Up
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Monica Muñoz Úbeda Dr. Fabio Carniato Dr. Valeria Catanzaro Sergio Padovan Dr. Cristina Grange Dr. Stefano Porta Dr. Carla Carrera Prof. Lorenzo Tei Dr. Giuseppe Digilio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(23):7716-7720
The redox microenvironment within a cell graft can be considered as an indicator to assess whether the graft is metabolically active or hypoxic. We present a redox‐responsive MRI probe based on porous silica microparticles whose surface has been decorated with a Gd‐chelate through a disulphide bridge. Such microparticles are designed to be interspersed with therapeutic cells within a biocompatible hydrogel. The onset of reducing conditions within the hydrogel is paralleled by an increased clearance of Gd, that can be detected by MRI. 相似文献
958.
Synthesis and Rearrangement of P‐Nitroxyl‐Substituted PIII and PV Phosphanes: A Combined Experimental and Theoretical Case Study
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Tobias Heurich Dr. Zheng‐Wang Qu Dr. Senada Nožinović Dr. Gregor Schnakenburg Dr. Hideto Matsuoka Prof. Dr. Stefan Grimme Prof. Dr. Olav Schiemann Prof. Dr. Rainer Streubel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(29):10102-10110
Low‐temperature generation of P‐nitroxyl phosphane 2 (Ph2POTEMP), which was obtained by the reaction of Ph2PH ( 1 ) with two equivalents of TEMPO, is presented. Upon warming, phosphane 2 decomposed to give P‐nitroxyl phosphane P‐oxide 3 (Ph2P(O)OTEMP) as one of the final products. This facile synthetic protocol also enabled access to P‐sulfide and P‐borane derivatives 7 and 13 , respectively, by using Ph2P(S)H ( 6 ) or Ph2P(BH3)H ( 11 ) and TEMPO. Phosphane sulfide 7 revealed a rearrangement to phosphane oxide 8 (Ph2P(O)STEMP) in CDCl3 at ambient temperature, whereas in THF, thermal decomposition of sulfide 7 yielded salt 10 ([TEMP‐H2][Ph2P(S)O]). As well as EPR and detailed NMR kinetic studies, indepth theoretical studies provided an insight into the reaction pathways and spin‐density distributions of the reactive intermediates. 相似文献
959.
Reactivity of [M2(μ‐Cl)2(cod)2] (M=Ir,Rh) and [Ru(Cl)2(cod)(CH3CN)2] with Na[H2B(bt)2]: Formation of Agostic versus Borate Complexes
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
K. Bakthavachalam K. Yuvaraj Mohammad Zafar Prof. Dr. Sundargopal Ghosh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(48):17291-17297
Treatment of [M2(μ‐Cl)2(cod)2] (M=Ir and Rh) with Na[H2B(bt)2] (cod=1,5‐cyclooctadiene and bt=2‐mercaptobenzothiazolyl) at low temperature led to the formation of dimetallaheterocycles [(Mcod)2(bt)2], 1 and 2 ( 1 : M=Ir and 2 : M=Rh) and a borate complex [Rh(cod){κ2‐S,S′‐H2B(bt)2}], 3 . Compounds 1 and 2 are structurally characterized metal analogues of 1,5‐cyclooctadiene. Metal–metal bond distances of 3.6195(9) Å in 1 and 3.6749(9) Å in 2 are too long to consider as bonding. In an attempt to generate the Ru analogue of 1 and 2 , that is [(Rucod)2(bt)2], we have carried out the reaction of [Ru(Cl)2(cod)(CH3CN)2] with Na[H2B(bt)2]. Interestingly, the reaction yielded agostic complexes [Ru(cod)L{κ3‐H,S,S′‐H2B(bt)2}], 4 and 5 ( 4 : L=Cl; 5 : L=C7H4NS2). One of the key differences between 4 and 5 is the presence of different ancillary ligands at the metal center. The natural bond orbital (NBO) analysis of 1 and 2 shows that there is four lone pairs of electrons on each metal center with a significant amount of d character. Furthermore, the electronic structures and the bonding of these complexes have been established on the ground of quantum‐chemical calculations. All of the new compounds were characterized by IR, 1H, 11B, 13C NMR spectroscopy, and X‐ray crystallographic analysis. 相似文献
960.