全文获取类型
收费全文 | 24835篇 |
免费 | 831篇 |
国内免费 | 158篇 |
专业分类
化学 | 16586篇 |
晶体学 | 206篇 |
力学 | 399篇 |
综合类 | 4篇 |
数学 | 4085篇 |
物理学 | 4544篇 |
出版年
2023年 | 159篇 |
2022年 | 398篇 |
2021年 | 480篇 |
2020年 | 396篇 |
2019年 | 457篇 |
2018年 | 425篇 |
2017年 | 412篇 |
2016年 | 806篇 |
2015年 | 691篇 |
2014年 | 758篇 |
2013年 | 1421篇 |
2012年 | 1500篇 |
2011年 | 1728篇 |
2010年 | 1080篇 |
2009年 | 1042篇 |
2008年 | 1511篇 |
2007年 | 1431篇 |
2006年 | 1336篇 |
2005年 | 1231篇 |
2004年 | 987篇 |
2003年 | 837篇 |
2002年 | 715篇 |
2001年 | 506篇 |
2000年 | 448篇 |
1999年 | 364篇 |
1998年 | 281篇 |
1997年 | 283篇 |
1996年 | 343篇 |
1995年 | 243篇 |
1994年 | 257篇 |
1993年 | 244篇 |
1992年 | 232篇 |
1991年 | 189篇 |
1990年 | 181篇 |
1989年 | 140篇 |
1988年 | 131篇 |
1987年 | 149篇 |
1986年 | 139篇 |
1985年 | 164篇 |
1984年 | 173篇 |
1983年 | 117篇 |
1982年 | 135篇 |
1981年 | 112篇 |
1980年 | 116篇 |
1979年 | 88篇 |
1978年 | 76篇 |
1977年 | 77篇 |
1976年 | 68篇 |
1975年 | 52篇 |
1973年 | 64篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
861.
Dr. Saida Majdoub Dr. Zoltán Garda Alexandre C. Oliveira Dr. Inga Relich Agnès Pallier Dr. Sara Lacerda Dr. Christelle Hureau Dr. Carlos F. G. C. Geraldes Dr. Jean-François Morfin Dr. Éva Tóth 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(6):2009-2020
Metal chelates targeted to amyloid peptides are widely explored as diagnostic tools or therapeutic agents. The attachment of a metal complex to amyloid recognition units typically leads to a decrease in peptide affinity. We show here that by separating a macrocyclic GdL chelate and a PiB targeting unit with a long hydrophobic C10 linker, it is possible to attain nanomolar affinities for both Aβ1-40 (Kd=4.4 nm ) and amylin (Kd=4.5 nm ), implicated, respectively in Alzheimer's disease and diabetes. The Scatchard analysis of surface plasmon resonance data obtained for a series of amphiphilic, PiB derivative GdL complexes indicate that their Aβ1-40 or amylin binding affinity varies with their concentration, thus micellar aggregation state. The GdL chelates also affect peptide aggregation kinetics, as probed by thioflavin-T fluorescence assays. A 2D NMR study allowed identifying that the hydrophilic region of Aβ1-40 is involved in the interaction between the monomer peptide and the Gd3+ complex. Finally, ex vivo biodistribution experiments were conducted in healthy mice by using 111In labeled analogues. Their pancreatic uptake, ∼3 %ID g−1, is promising to envisage amylin imaging in diabetic animals. 相似文献
862.
Dr. Rebeca Arevalo Dr. Ramón López Prof. Larry R. Falvello Dr. Lucía Riera Dr. Julio Perez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(1):379-389
The reactions of [Re(N-N)(CO)3(PMe3)]OTf (N-N=2,2′-bipyridine, bipy; 1,10-phenanthroline, phen) compounds with tBuLi and with LiHBEt3 have been explored. Addition to the N-N chelate took place with different site-selectivity depending on both chelate and nucleophile. Thus, with tBuLi, an unprecedented addition to C5 of bipy, a regiochemistry not accessible for free bipy, was obtained, whereas coordinated phen underwent tBuLi addition to C2 and C4. Remarkably, when LiHBEt3 reacted with [Re(bipy)(CO)3(PMe3)]OTf, hydride addition to the 4 and 6 positions of bipy triggered an intermolecular cyclodimerization of two dearomatized pyridyl rings. In contrast, hydride addition to the phen analog resulted in partial reduction of one pyridine ring. The resulting neutral ReI products showed a varied reactivity with HOTf and with MeOTf to yield cationic complexes. These strategies rendered access to ReI complexes containing bipy- and phen-derived chelates with several C(sp3) centers. 相似文献
863.
Dr. Eva González-Freire Dr. Federica Novelli Antonio Pérez-Estévez Prof. Dr. Rafael Seoane Dr. Manuel Amorín Prof. Dr. Juan R. Granja 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(9):3029-3038
A new class of amphipathic cyclic peptides, which assemble in bacteria membranes to form polymeric supramolecular nanotubes giving them antimicrobial properties, is described. The method is based on the use of two orthogonal clickable transformations to incorporate different hydrophobic or hydrophilic moieties in a simple, regioselective, and divergent manner. The resulting cationic amphipathic cyclic peptides described in this article exhibit strong antimicrobial properties with a broad therapeutic window. Our studies suggest that the active form is the nanotube resulted from the parallel stacking of the cyclic peptide precursors. Several techniques, CD, FTIR, fluorescence, and STEM, among others, confirm the nanotube formation. 相似文献
864.
Dr. Manuel Vázquez Sulleiro Ramiro Quirós-Ovies Mariano Vera-Hidalgo Dr. I. Jénnifer Gómez Dr. Víctor Sebastián Prof. Jesús Santamaría Prof. Emilio M. Pérez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(9):2993-2996
The combination of 2D materials opens a wide range of possibilities to create new-generation structures with multiple applications. Covalently cross-linked approaches are a ground-breaking strategy for the formation of homo or heterostructures made by design. However, the covalent assembly of transition metal dichalcogenides flakes is relatively underexplored. Here, a simple covalent cross-linking method to build 2H-MoS2–MoS2 homostructures is described, using commercially available bismaleimides. These assemblies are mainly connected vertically, basal plane to basal plane, creating specific molecular sized spaces between MoS2 sheets. Therefore, this straightforward approach gives access to the controlled connection of sulfide-based 2D materials. 相似文献
865.
Dr. Robert Ludmerczki Prof. Luca Malfatti Dr. Luigi Stagi Dr. Manuela Meloni Prof. Carlo Maria Carbonaro Prof. Maria Francesca Casula Dr. Dóra Bogdán Dr. Stefania Mura Prof. István M. Mándity Prof. Plinio Innocenzi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(7):2543-2550
Carbonized polymer dots (CPDs), a peculiar type of carbon dots, show extremely high quantum yields, making them very attractive nanostructures for application in optics and biophotonics. The origin of the strong photoluminescence of CPDs resides in a complicated interplay of several radiative mechanisms. To understand the correlation between CPD processing and properties, the early stage formation of carbonized polymer dots has been studied. In the synthesis, citric acid monohydrate and 2-amino-2-(hydroxymethyl)propane-1,3-diol have been thermally degraded at 180 °C. The use of an oil bath instead of a more traditional hydrothermal reactor has allowed the CPD properties to be monitored at different reactions times. Transmission electron microscopy, time-resolved photoluminescence, nuclear magnetic resonance, infrared, and Raman spectroscopy have revealed the formation of polymeric species with amide and ester bonds. Quantum chemistry calculations have been employed to investigate the origin of CPD electronic transitions. At short reaction times, amorphous C-dots with 80 % quantum yield, have been obtained. 相似文献
866.
867.
868.
F. Lieneweg J. Guzmán A. Ara J. W. Teiss O. R. Wagner C. del Fresno L. Valdés und Je. I. Denissow 《Fresenius' Journal of Analytical Chemistry》1941,122(7-8):291-292
Ohne Zusammenfassung 相似文献
869.
870.