全文获取类型
收费全文 | 1369篇 |
免费 | 47篇 |
国内免费 | 4篇 |
专业分类
化学 | 950篇 |
晶体学 | 10篇 |
力学 | 45篇 |
数学 | 147篇 |
物理学 | 268篇 |
出版年
2023年 | 7篇 |
2022年 | 11篇 |
2021年 | 14篇 |
2020年 | 17篇 |
2019年 | 21篇 |
2018年 | 13篇 |
2017年 | 10篇 |
2016年 | 27篇 |
2015年 | 32篇 |
2014年 | 61篇 |
2013年 | 73篇 |
2012年 | 73篇 |
2011年 | 102篇 |
2010年 | 46篇 |
2009年 | 47篇 |
2008年 | 94篇 |
2007年 | 84篇 |
2006年 | 77篇 |
2005年 | 65篇 |
2004年 | 56篇 |
2003年 | 36篇 |
2002年 | 40篇 |
2001年 | 17篇 |
2000年 | 26篇 |
1999年 | 18篇 |
1998年 | 13篇 |
1997年 | 9篇 |
1996年 | 16篇 |
1995年 | 11篇 |
1994年 | 11篇 |
1993年 | 15篇 |
1992年 | 6篇 |
1991年 | 9篇 |
1990年 | 13篇 |
1989年 | 13篇 |
1988年 | 12篇 |
1987年 | 10篇 |
1985年 | 13篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 12篇 |
1981年 | 14篇 |
1980年 | 17篇 |
1979年 | 16篇 |
1978年 | 11篇 |
1977年 | 15篇 |
1976年 | 7篇 |
1975年 | 7篇 |
1974年 | 19篇 |
1973年 | 12篇 |
排序方式: 共有1420条查询结果,搜索用时 15 毫秒
31.
Dr. Benoît Bertrand Dr. Candice Botuha Jérémy Forté Dr. Héloïse Dossmann Dr. Michèle Salmain 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(56):12846-12861
The two independent and coordination sites of a newly synthesized bis[2-(hydroxyphenyl)-1,2,4-triazole] platform have been exploited to prepare four monometallic neutral ()PtII complexes carrying DMSO, pyridine, triphenylphosphine, or N-heterocyclic carbene as the fourth ligand. Then, the second coordination site was used to introduce an IR-active rhenium tricarbonyl entity, affording the four corresponding heterobimetallic neutral PtII/ReI complexes, as well as a cationic PtII/ReI derivative. X-ray crystallographic studies showed that distortion of the organic platform occurred to accommodate the coordination geometry of both metal centers. No ligand exchange or transchelation occurred upon incubation of the PtII complexes in aqueous environment or in the presence of FeIII, respectively. The antiproliferative activity of the ligand and complexes was first screened on the triple-negative breast cancer cell line MDA-MB-231. Then, the IC50 values of the most active candidates were determined on a wider panel of human cancer cells (MDA-MB-231, MCF-7, and A2780), as well as on a nontumorigenic cell line (MCF-10A). Low micromolar activities were reached for the complexes carrying a DMSO ligand, making them the first examples of highly active, but hydrolytically stable, PtII complexes. Finally, the characteristic mid-IR signature of the {Re(CO)3} fragment in the Pt/Re heterobimetallic complexes was used to quantify their uptake in breast cancer cells. 相似文献
32.
J. P. Majoral G. Bertrand A. Baceiredo M. Mulliez R. Schmutzler 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):221-224
Abstract First evidence for a Curtius type rearrangement involving a pentacoordinated atom and charged species are described 相似文献
33.
The synthesis of some new functionalized quinolyl derivatives relies on the 1,3‐dipolar cycloaddition of an azomethine ylide, generated from sarcosine and paraformaldehyde, to quinolyl α,β‐unsaturated esters, followed by oxidation of the pyrrolidinyl moiety to pyrrole with activated MnO2. 相似文献
34.
35.
Dr. Sylvain Achelle Dr. Jean‐Pierre Malval Dr. Stéphane Aloïse Dr. Alberto Barsella Dr. Arnaud Spangenberg Dr. Loic Mager Dr. Huriye Akdas‐Kilig Dr. Jean‐Luc Fillaut Prof. Bertrand Caro Prof. Françoise Robin‐le Guen 《Chemphyschem》2013,14(12):2725-2736
The nonlinear properties and the photophysical behavior of two π‐conjugated chromophores that incorporate an electron‐deficient pyrimidine core (A) and γ‐methylenepyrans as terminal donor (D) groups have been thoroughly investigated. Both dipolar and quadrupolar branching strategies are explored and rationalized on the basis of the Frenkel exciton model. Even though a cooperative effect is clearly observed if the dimensionality is increased, the nonlinear optical (NLO) response of this series is moderate if one considers the nature of the D/A couple and the size of the chromophores (as measured by the number of π electrons). This effect was attributed to a disruption in the electronic conjugation within the dyes’ scaffold for which the geometry deviates from planarity owing to a noticeable twisting of the pyranylidene end‐groups. This latter structural parameter also has a strong influence on the excited‐state dynamics, which leads to a very efficient fluorescence quenching. 相似文献
36.
Arbia Khemiri Bertrand Naudin Xavier Franck Philippe Chan Tchi Song Thierry Jouenne Pascal Cosette 《Analytical and bioanalytical chemistry》2013,405(30):9835-9842
In prokaryote organisms, N-glycosylation of proteins is often correlated to cell–cell recognition and extracellular events. Those glycoproteins are potential targets for infection control. To date, many surface-glycosylated proteins from bacterial pathogens have been described. However, N-linked Pseudomonas surface-associated glycoproteins remain underexplored. We report a combined enrichment and labeling strategy to identify major glycoproteins on the outside of microorganisms. More precisely, bacteria were exposed to a mix of biotinylated lectins able to bind with glycoproteins. The latter were then recovered by avidin beads, digested with trypsin, and submitted to mass spectrometry. The targeted mixture of glycoproteins was additionally deglycosylated in the presence of H2 18O to incorporate 18O during PNGase F treatment and were also analyzed using mass spectrometry. This approach allowed us to identify a few tens of potential N-glycoproteins, among which flagellin FliC was the most abundant. To detect the possible sites of FliC modifications, a de novo sequencing step was also performed to discriminate between spontaneous deamidation and N-glycan loss. This approach led to the proposal of three potential N-glycosylated sites on the primary sequence of FliC: N26, N69, and N439, with two of these three asparagines belonging to an N-X-(S/T) consensus sequence. These observations suggest that flagellin FliC is a heterogeneous protein mixture containing both O- and N-glycoforms. Figure
Analytical scenario developed for bacterial glycoprotein enrichment. This strategy includes three main steps: (1) exposure of Pseudomonas aeruginosa cells to a mixture of biotinylated lectins [wheat germ agglutinin (WGA) and concanavalin A (ConA)]; (2) enrichment of N-glycoproteins by elution with avidin beads; and (3) mass spectrometry (MS) identification and characterization of intact and deglycosylated peptides before and after H2 18O PNGase F enzymatic treatment, respectively 相似文献
37.
38.
L. Larios-López D. Navarro-Rodríguez E. M. Arias-Marín I. Moggio C. V. Reyes-Castañeda B. Donnio 《Liquid crystals》2013,40(4):423-433
A series of linear oligo (p-phenylene)s containing three, five and seven phenylene groups, modified with short lateral and long terminal alkoxy chains, were synthesized via Palladium complex-catalysed cross-coupling reactions. The thermotropic liquid crystalline and UV absorption/emission properties of these compounds were studied. It was observed that tri (p -phenylene)s develop a rich mesomorphism including tilted smectic type mesophases (SmC and SmF/SmI) and the nematic phase, whereas penta- and hepta-(p-phenylene)s substituted with short lateral chains develop only the nematic phase. From these observations it is clear that the short lateral chains hinder the layered molecular packing typical of smectic phases and promote the formation of the less ordered liquid-like nematic phase. Mesophases appeared at lower temperatures when longer end chains were used. The optical properties studied by UV-Vis and emission spectroscopy indicate that these systems are promising candidates for blue-emitting layers in electroluminescent devices. 相似文献
39.
In the course of our syntheses of functionalised pyridine and quinoline derivatives, we examined the reactivities of pyridine and quinoline N-oxides towards the nucleophilic addition of acidic carbon derivatives. Different activating reagents were used, such as PyBroP, triflic anhydride and a combination of pyrrolidine phosphoramide and triflic anhydride. 相似文献
40.
We show that the particle-hole conjugate of the Pfaffian state-or "anti-Pfaffian" state-is in a different universality class from the Pfaffian state, with different topological order. The two states can be distinguished easily by their edge physics: their edges differ in both their thermal Hall conductance and their tunneling exponents. At the same time, the two states are exactly degenerate in energy for a nu=5/2 quantum Hall system in the idealized limit of zero Landau level mixing. Thus, both are good candidates for the observed sigma_{xy}=5/2(e;{2}/h) quantum Hall plateau. 相似文献