全文获取类型
收费全文 | 572篇 |
免费 | 44篇 |
国内免费 | 1篇 |
专业分类
化学 | 499篇 |
力学 | 3篇 |
数学 | 46篇 |
物理学 | 69篇 |
出版年
2024年 | 2篇 |
2023年 | 18篇 |
2022年 | 40篇 |
2021年 | 55篇 |
2020年 | 30篇 |
2019年 | 18篇 |
2018年 | 17篇 |
2017年 | 13篇 |
2016年 | 32篇 |
2015年 | 26篇 |
2014年 | 24篇 |
2013年 | 24篇 |
2012年 | 37篇 |
2011年 | 34篇 |
2010年 | 14篇 |
2009年 | 8篇 |
2008年 | 30篇 |
2007年 | 29篇 |
2006年 | 16篇 |
2005年 | 28篇 |
2004年 | 17篇 |
2003年 | 20篇 |
2002年 | 13篇 |
2001年 | 10篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 1篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有617条查询结果,搜索用时 15 毫秒
481.
Dr. Valeria Gabrielli Dr. Juan C. Muñoz-García Dr. Giulia Pergolizzi Dr. Peterson de Andrade Prof. Yaroslav Z. Khimyak Prof. Robert A. Field Dr. Jesús Angulo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(63):15688-15698
β-1→4-Glucan polysaccharides like cellulose, derivatives and analogues, are attracting attention due to their unique physicochemical properties, as ideal candidates for many different applications in biotechnology. Access to these polysaccharides with a high level of purity at scale is still challenging, and eco-friendly alternatives by using enzymes in vitro are highly desirable. One prominent candidate enzyme is cellodextrin phosphorylase (CDP) from Ruminiclostridium thermocellum, which is able to yield cellulose oligomers from short cellodextrins and α-d -glucose 1-phosphate (Glc-1-P) as substrates. Remarkably, its broad specificity towards donors and acceptors allows the generation of highly diverse cellulose-based structures to produce novel materials. However, to fully exploit this CDP broad specificity, a detailed understanding of the molecular recognition of substrates by this enzyme in solution is needed. Herein, we provide a detailed investigation of the molecular recognition of ligands by CDP in solution by saturation transfer difference (STD) NMR spectroscopy, tr-NOESY and protein-ligand docking. Our results, discussed in the context of previous reaction kinetics data in the literature, allow a better understanding of the structural basis of the broad binding specificity of this biotechnologically relevant enzyme. 相似文献
482.
Agricola Ilka Dileo Giulia Stecker Leander 《Annals of Global Analysis and Geometry》2021,60(1):111-141
Annals of Global Analysis and Geometry - We show that every 3- $$(\alpha ,\delta )$$ -Sasaki manifold of dimension $$4n + 3$$ admits a locally defined Riemannian submersion over a quaternionic... 相似文献
483.
484.
Alessandro G. Fois Panagiotis Paliogiannis Valentina Scano Stefania Cau Sergio Babudieri Roberto Perra Giulia Ruzzittu Elisabetta Zinellu Pietro Pirina Ciriaco Carru Luigi B. Arru Alessandro Fancellu Michele Mondoni Arduino A. Mangoni Angelo Zinellu 《Molecules (Basel, Switzerland)》2020,25(23)
Background. The rapid onset of a systemic pro-inflammatory state followed by acute respiratory distress syndrome is the leading cause of mortality in patients with COVID-19. We performed a retrospective observational study to explore the capacity of different complete blood cell count (CBC)-derived inflammation indexes to predict in-hospital mortality in this group. Methods. The neutrophil to lymphocyte ratio (NLR), derived NLR (dNLR), platelet to lymphocyte ratio (PLR), mean platelet volume to platelet ratio (MPR), neutrophil to lymphocyte × platelet ratio (NLPR), monocyte to lymphocyte ratio (MLR), systemic inflammation response index (SIRI), systemic inflammation index (SII), and the aggregate index of systemic inflammation (AISI) were calculated on hospital admission in 119 patients with laboratory confirmed COVID-19. Results. Non-survivors had significantly higher AISI, dNLR, NLPR, NLR, SII, and SIRI values when compared to survivors. Similarly, Kaplan–Meier survival curves showed significantly lower survival in patients with higher AISI, dNLR, MLR, NLPR, NLR, SII, and SIRI. However, after adjusting for confounders, only the SII remained significantly associated with survival (HR = 1.0001; 95% CI, 1.0000–1.0001, p = 0.029) in multivariate Cox regression analysis. Conclusions. The SII on admission independently predicts in-hospital mortality in COVID-19 patients and may assist with early risk stratification in this group. 相似文献
485.
Giulia Lavarda Dr. Nicholus Bhattacharjee Dr. Giuseppe Brancato Prof. Tomás Torres Dr. Giovanni Bottari 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(47):21410-21415
In recent years, several tetracyanobuta-1,3-diene (TCBD) conjugates have been prepared by linking the tetracyano unit to various electroactive moieties. These push–pull conjugates, besides showing interesting physicochemical properties, are axially chiral, a feature arising from the restricted rotation around the central bond of the butadiene. Yet, only in a few cases, separation and isolation of the enantiomers have been successfully achieved, owing to the configurational lability of the corresponding enantiopure species. Herein, we report the first example of photo- and electroactive TCBD-based derivatives showing unprecedented configurational stability and a peculiar light-triggered enantiomer conversion mechanism enabled by triple-state photogeneration. These systems represent a nice addition to the fast-increasing arsenal of artificial, light-controllable molecular switches. 相似文献
486.
Dr. Stefano Carli Dr. Giulia Fioravanti Dr. Andrea Armirotti Dr. Francesca Ciarpella Dr. Mirko Prato Dr. Giuliana Ottonello Dr. Marco Salerno Dr. Alice Scarpellini Dr. Daniela Perrone Dr. Elena Marchesi Dr. Davide Ricci Prof. Luciano Fadiga 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(9):2322-2329
Localized drug delivery represents one of the most challenging uses of systems based on conductive polymer films. Typically, anionic drugs are incorporated within conductive polymers through electrostatic interaction with the positively charged polymer. Following this approach, the synthetic glucocorticoid dexamethasone phosphate is often delivered from neural probes to reduce the inflammation of the surrounding tissue. In light of the recent literature on the neuroprotective and anti-inflammatory properties of tauroursodeoxycholic acid (TUDCA), for the first time, this natural bile acid was incorporated within poly(3,4-ethylenedioxythiophene) (PEDOT). The new material, PEDOT—TUDCA, efficiently promoted an electrochemically controlled delivery of the drug, while preserving optimal electrochemical properties. Moreover, the low cytotoxicity observed with viability assays, makes PEDOT–TUDCA a good candidate for prolonging the time span of chronic neural recording brain implants. 相似文献
487.
Dr. Deborah Quaglio Laura Mangiardi Dr. Giulia Venditti Cristina Del Plato Francesca Polli Dr. Francesca Ghirga Prof. Gabriele Favero Prof. Marco Pierini Prof. Bruno Botta Prof. Franco Mazzei 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(38):8400-8406
One of the main problems in the development of immunosensors is to overcome the complexity of binding antibodies to the sensor surface. Most immobilizing methods lead to a random orientation of antibodies with a lower binding site density and immunoaffinity. In order to control the orientation of antibody immobilization, several resorc[4]arene derivatives were designed and synthesized. After the spectroscopic characterization of resorc[4]arene self-assembled monolayers (SAMs) onto gold films, the surface coverage and the orientation of insulin antibody (Ab-Ins) were assessed by a surface plasmon resonance (SPR) technique and compared with a random immobilization method. Experimental results combined with theoretical studies confirmed the dipole–dipole interaction as an important factor in antibody orientation and demonstrated the importance of the upper rim functionalization of resorcarenes. Accordingly, resorcarene 5 showed a major binding force towards Ab-Ins thanks to the H-bond interactions with the amine protein groups. Based on these findings, the resorcarene-based immunosensor is a powerful system with improved sensitivity providing new insight into sensor development. 相似文献
488.
489.
Electrochemical detection of nonelectroactive contaminants can be successfully faced via the use of indirect detection strategies. These strategies can provide sensitive and selective responses often coupled with portable and user-friendly analytical tools. Indirect detection strategies are usually based on the change in the signal of an electroactive probe, induced by the presence of the target molecule at a modified electrode. This critical review aims at addressing the developments in indirect electrosensing strategies for nonelectroactive contaminants in food and environmental analysis in the last few years. Emphasis is given to the strategy design, the electrode modifiers used and the feasibility of technological transfer. 相似文献
490.
Giulia Siciliano Dr. Michela Corricelli Dr. Rosa Maria Iacobazzi Prof. Fabio Canepa Dr. Daniela Comegna Prof. Elisabetta Fanizza Dr. Annarita Del Gatto Dr. Michele Saviano Prof. Valentino Laquintana Dr. Roberto Comparelli Dr. Giuseppe Mascolo Dr. Sapia Murgolo Dr. Marinella Striccoli Prof. Angela Agostiano Prof. Nunzio Denora Dr. Laura Zaccaro Prof. M. Lucia Curri Dr. Nicoletta Depalo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(48):11048-11059
Efforts are made to perform an early and accurate detection of hepatocellular carcinoma (HCC) by simultaneous exploiting multiple clinically non-invasive imaging modalities. Original nanostructures derived from the combination of different inorganic domains can be used as efficient contrast agents in multimodal imaging. Superparamagnetic iron oxide nanoparticles (SPIONs) and Au nanoparticles (NPs) possess well-established contrasting features in magnetic resonance imaging (MRI) and X-ray computed tomography (CT), respectively. HCC can be targeted by using specific carbohydrates able to recognize asialoglycoprotein receptor 1 (ASGPR1) overexpressed in hepatocytes. Here, two different thiocarbohydrate ligands were purposely designed and alternatively conjugated to the surface of Au-speckled silica-coated SPIONs NPs, to achieve two original nanostructures that could be potentially used for dual mode targeted imaging of HCC. The results indicated that the two thiocarbohydrate decorated nanostructures possess convenient plasmonic/superparamagnetic properties, well-controlled size and morphology and good selectivity for targeting ASGPR1 receptor. 相似文献