全文获取类型
收费全文 | 910篇 |
免费 | 220篇 |
国内免费 | 10篇 |
专业分类
化学 | 1132篇 |
晶体学 | 1篇 |
物理学 | 7篇 |
出版年
2024年 | 2篇 |
2023年 | 9篇 |
2022年 | 14篇 |
2021年 | 26篇 |
2020年 | 76篇 |
2019年 | 35篇 |
2018年 | 32篇 |
2017年 | 26篇 |
2016年 | 80篇 |
2015年 | 72篇 |
2014年 | 62篇 |
2013年 | 85篇 |
2012年 | 57篇 |
2011年 | 51篇 |
2010年 | 57篇 |
2009年 | 56篇 |
2008年 | 44篇 |
2007年 | 42篇 |
2006年 | 48篇 |
2005年 | 51篇 |
2004年 | 46篇 |
2003年 | 54篇 |
2002年 | 14篇 |
2001年 | 12篇 |
2000年 | 9篇 |
1999年 | 14篇 |
1998年 | 5篇 |
1997年 | 21篇 |
1996年 | 12篇 |
1995年 | 17篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有1140条查询结果,搜索用时 31 毫秒
121.
122.
Liquid‐Crystalline Mesogens Based on Cyclo[6]aramides: Distinctive Phase Transitions in Response to Macrocyclic Host–Guest Interactions
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)
Xiaowei Li Dr. Bao Li Long Chen Jinchuan Hu Chengdanyang Wen Prof. Qingdong Zheng Prof. Lixin Wu Dr. Huaqiang Zeng Prof. Bing Gong Prof. Lihua Yuan 《Angewandte Chemie (International ed. in English)》2015,54(38):11147-11152
Producing macrocyclic mesogens that are responsive to guest encapsulation presents a significant challenge. Cyclo[6]aramides, a type of macrocycle with a hydrogen‐bond‐constrained backbone, exhibit thermotropic lamellar, discotic nematic, hexagonal, and rectangular columnar mesophases over a considerably wide temperature range, including at room temperature. Additionally, cyclo[6]aramides show unusual mesophase transitions from lamellar to hexagonal columnar phase mediated by macrocyclic host–guest (H–G) interactions between the macrocycles and alkylammonium salts. The phase transition, triggered by an organic guest engaging in H–G interactions with a macrocyclic cavity, provides a novel strategy for manipulating the properties of liquid‐crystalline materials. The crystal structure of a homologous cyclo[6]aramide reveals a disk‐shaped, near‐planar molecular backbone that facilitates intermolecular π–π stacking and leads to columnar assembly. 相似文献
123.
Electrolytic Macrocyclizations: Scalable Synthesis of a Diazonamide‐Based Drug Development Candidate
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)
Dr. Hui Ding Patrick L. DeRoy Christian Perreault Dr. Alexandre Larivée Dr. Arshad Siddiqui Dr. Charles G. Caldwell Susan Harran Prof. Dr. Patrick G. Harran 《Angewandte Chemie (International ed. in English)》2015,54(16):4818-4822
An electrochemical method to synthesize the core macrolactam of diazonamides is described. Large ring‐forming dehydrogenation is initiated by anodic oxidation at a graphite surface. The reaction requires no tailoring of the substrate and occurs at ambient temperature in aqueous DMF in an undivided cell open to air. This unique chemistry has enabled a concise, scalable preparation of DZ‐2384; a refined analog of diazonamide A slated for clinical development as a cancer therapeutic. 相似文献
124.
Triple Emission from p‐Dimethylaminobenzonitrile–Cucurbit[8]uril Triggers the Elusive Excimer Emission
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. Mhejabeen Sayed Dr. Frank Biedermann Dr. Vanya D. Uzunova Khaleel I. Assaf Dr. Achikanath C. Bhasikuttan Dr. Haridas Pal Prof. Werner M. Nau Dr. Jyotirmayee Mohanty 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(2):691-696
The intriguing dual‐emission behavior of p‐ dimethylaminobenzonitrile (DMABN) and the identity of the associated excited states is, arguably, the most extensively investigated and also controversially discussed molecule‐ specific phenomenon of modern photochemistry. We have now found a new, third fluorescence band when DMABN is encapsulated within the water‐soluble molecular container cucurbit[8]uril (CB8). It is centered between the previously observed emissions and assigned to the elusive excimer emission from DMABN through 1:2 CB8:DMABN complex formation. Heating of the CB8 ? (DMABN)2 complex from 0 to 100 °C results in the dissociation of the ternary complex and restoration of the dual‐emission properties of the monomer. Alternatively, monomer emission can be obtained by selecting cucurbit[7]uril (CB7), a host homologue that is too small to accommodate two DMABN molecules, or by introducing ethyl instead of methyl groups at the amino terminus of the aminobenzonitrile guest. 相似文献
125.
Torands Revisited: Metal Sequestration and Self‐Assembly of Cyclo‐2,9‐tris‐1,10‐phenanthroline Hexaaza Macrocycles
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. Matthias Georg Schwab Dr. Masayoshi Takase Dr. Alexey Mavrinsky Dr. Wojciech Pisula Prof. Dr. Xinliang Feng Dr. José A. Gámez Prof. Dr. Walter Thiel Dr. Kunal S. Mali Prof. Dr. Steven de Feyter Prof. Dr. Klaus Müllen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(23):8426-8434
A series of novel toroidal cyclo‐2,9‐tris‐1,10‐phenanthroline macrocycles with an unusual hexaaza cavity are reported. Nickel‐mediated Yamamoto aryl–aryl coupling was found to be a versatile tool for the cyclotrimerization of functionalized 1,10‐phenathroline precursors. Due to the now improved processability, both liquid‐crystalline behavior in the bulk phase and two‐dimensional self‐assembly at the molecular level could be studied, for the first time, for a torand system. The macrocycles exhibited a strong affinity for the complexation of different metal cations, as evidenced by MALDI‐TOF analysis and spectroscopic methods. Experimental results were correlated to an extensive computational study of the cyclo‐2,9‐tris‐1,10‐phenanthroline cavity and its binding mode for metal cations. Due to the combination of several interesting features, toroidal macrocycles may find future applications in the field of ion and charge transport through molecular channels, as well as for chemical sensing and molecular writing in surface‐confined monolayers under STM conditions. 相似文献
126.
Indachlorins: Nonplanar Indanone‐Annulated Chlorin Analogues with Panchromatic Absorption Spectra between 300 and 900 nm
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. Lalith P. Samankumara Dr. Sarina J. Dorazio Dr. Joshua Akhigbe Ruoshi Li Dr. Arunpatcha Nimthong‐Roldán Dr. Matthias Zeller Prof. Dr. Christian Brückner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(31):11118-11128
Indaphyrins, pyrrole‐modified porphyrins containing a cleaved pyrrole β,β′‐bond and two annulated indanone moieties, possess unusually broadened and redshifted UV/Vis spectra because of their π‐expanded chromophores. The parent free base indaphyrin has been crystallographically characterized, highlighting its strongly ruffled conformation incorporating a helimeric twist. It was shown to be susceptible to regiospecific derivatizations at the opposite side of the ring‐cleaved pyrrole (dihydroxylation, followed by functional group transformations of the resulting diol functionality), generating indaphyrin‐based chlorin analogues, indachlorins, that incorporate a dihydroxypyrroline, pyrrolindione, oxazolone, or a morpholine moiety. Structural modifications resulted in further broadening and hyper‐ and bathochromic shifts of the optical spectra, some of which possess a nearly panchromatic absorption between 300 to well above 900 nm. The extents to which these modifications affect their solid‐state conformations were analyzed. 相似文献
127.
Corrigendum: Cyclooctane Metathesis Catalyzed by Silica‐Supported Tungsten Pentamethyl [(SiO)W(Me)5]: Distribution of Macrocyclic Alkanes
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)
128.
Dr. Damien Lhenry Dr. Manuel Larrouy Dr. Claire Bernhard Dr. Victor Goncalves Dr. Olivier Raguin Dr. Peggy Provent Dr. Mathieu Moreau Dr. Bertrand Collin Dr. Alexandra Oudot Dr. Jean‐Marc Vrigneaud Dr. François Brunotte Dr. Christine Goze Prof. Franck Denat 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(37):13091-13099
In molecular imaging, multimodal imaging agents can provide complementary information, for improving the accuracy of disease diagnosis or enhancing patient management. In particular, optical/nuclear imaging may find important preclinical and clinical applications. To simplify the preparation of dual‐labeled imaging agents, we prepared versatile monomolecular multimodal imaging probe (MOMIP) platforms containing both a fluorescent dye (BODIPY) and a metal chelator (polyazamacrocycle). One of the MOMIP was conjugated to a cyclopeptide (i.e., octreotide) and radiolabeled with 111In. In vitro and in vivo studies of the resulting bioconjugate were conducted, highlighting the potential of these BODIPY‐based bimodal probes. This work also confirmed that the biovector and/or the bimodal probes must be chosen carefully, due to the impact of the MOMIP on the overall properties of the resulting imaging agent. 相似文献
129.
Synthesis of Cembranoid Analogues through Ring‐Closing Metathesis of Terpenoid Precursors: A Challenge Regarding Ring‐Size Selectivity
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)
Tanja Heidt Dr. Angelika Baro Prof. Andreas Köhn Prof. Sabine Laschat 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(35):12396-12404
A systematic study on ring‐closing metathesis with Grubbs II catalyst to cembranoid macrocycles is described. Acyclic terpenoids with a functional group X in the homoallylic position relative to an RCM active terminus and substituents R, R1 directly attached to the other terminal double bond were prepared from geraniol derived trienes and fragments that are based on bromoalkenes and dimethyl malonate. Such terpenoids were suitable precursors, despite the presence of competing double bonds in their framework. The size of R and R1 is crucial for successful macrocyclization. Whereas small alkyl substituents at the double bond directed the RCM towards six‐membered ring formation, cross metathesis leading to dimers dominated for bulkier alkyl groups. A similar result was obtained for precursors without functional group X. In the case of unsymmetrically substituted terpenoid precursor (R=Et, R1=Me) with homoallylic OTBS or OMe group, the RCM could be controlled towards formation of macrocyclic cembranoids, which were isolated with excellent E‐selectivity. The role of the substituents was further studied by quantum chemical calculations of simplified model substrates. Based on these results a mechanistic rationale is proposed. 相似文献
130.
Discrete Rectangles,Prisms, and Heterometallic Cages from a Conjugated Cp*Rh‐Based Building Block
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)
Xu‐Yu Shen Dr. Ying‐Ying Zhang Long Zhang Dr. Yue‐Jian Lin Prof. Guo‐Xin Jin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(47):16975-16981
By carefully selecting an existing synthetic strategy and suitable coordination subunits, constructing desired coordination geometries is no longer that difficult to accomplish. Herein, a new strategy to construct a series of unprecedented structures by using conjugated Cp*Rh‐based complex BN‐OTf (Cp*=η5‐C5Me5) as the building block is proposed. DFT calculations revealed extensive delocalized π bonds in the subunit. With BN‐OTf , rectangular macrocycles TN‐bpy and TN‐bpe were controllably synthesized. Single‐crystal XRD studies confirmed one‐dimensional stacking channels for the tetranuclear structure. Notably, the starting ligand imidazole‐4,5‐dicarboxylate was found to act not only as a tetradentate but also as a hexadentate ligand that can coordinate to further metal ions. Subsequently, [4 Rh+1 M] heterometallic complexes HMZ (M=Cu and Zn) were accessed by chelating borderline hard/soft Lewis acids. With TN‐Linker or HMZ , two routes resulted in the [8 Rh+2 M] heterometallic cages HMC (M=Cu and Zn) with excellent crystallinity and stability. Surprisingly, when BN‐OTf bonded to rhodium itself, triangular prisms TP‐Linker were obtained with high solubility after being linked by bipyridine linkers. Both the X‐ray structure and 1H NMR spectrum confirmed the novel isomerization of the triangular structures. All of the compounds were obtained in high yields and were fully characterized by 1H NMR spectroscopy, elemental analysis, IR spectroscopy, and in most cases single‐crystal X‐ray structure determination. 相似文献