全文获取类型
收费全文 | 1091篇 |
免费 | 55篇 |
国内免费 | 6篇 |
专业分类
化学 | 916篇 |
晶体学 | 9篇 |
力学 | 11篇 |
数学 | 116篇 |
物理学 | 100篇 |
出版年
2023年 | 12篇 |
2022年 | 37篇 |
2021年 | 43篇 |
2020年 | 21篇 |
2019年 | 24篇 |
2018年 | 25篇 |
2017年 | 8篇 |
2016年 | 41篇 |
2015年 | 49篇 |
2014年 | 43篇 |
2013年 | 73篇 |
2012年 | 85篇 |
2011年 | 109篇 |
2010年 | 46篇 |
2009年 | 57篇 |
2008年 | 95篇 |
2007年 | 66篇 |
2006年 | 46篇 |
2005年 | 73篇 |
2004年 | 52篇 |
2003年 | 29篇 |
2002年 | 31篇 |
2001年 | 9篇 |
2000年 | 4篇 |
1999年 | 9篇 |
1998年 | 8篇 |
1997年 | 2篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有1152条查询结果,搜索用时 15 毫秒
931.
Thomas Scattolin Sonia Giust Paola Bergamini Isabella Caligiuri Luciano Canovese Nicola Demitri Roberto Gambari Ilaria Lampronti Flavio Rizzolio Fabiano Visentin 《应用有机金属化学》2019,33(6)
A complete protocol for the synthesis of new palladacyclopentadienyl complexes with purine‐based carbenes as supporting ligands is described. The new organometallic compounds were exhaustively characterized using NMR and infrared spectroscopies and elemental analysis. The single‐crystal X‐ray structure of complex 2b coordinating also a triphenylphosphine was resolved. Some of these complexes showed an antiproliferative activity comparable to or better than that of cisplatin on two human ovarian cancer lines: A2780 (cisplatin‐sensitive) and A2780cis (cisplatin‐resistant). Moreover, for complexes 2 and 3 (coordinating one purine‐based N‐heterocyclic carbene ligand and one phosphine) the cytotoxicity is associated with an evident induction of apoptosis. Finally, complexes 3 , bearing one purine‐based N‐heterocyclic carbene ligand and one 1,3,5‐triaza‐7‐phosphaadamantane, proved practically inactive on non‐tumour fibroblast cells (MRC‐5). 相似文献
932.
Sonia Bahrani Mehrorang Ghaedi Tahere Taghipour Mohammad Javad Khoshnood Mansoorkhani Ahmad Reza Bagheri Abbas Ostovan 《应用有机金属化学》2018,32(1)
Well‐designed metal organic materials (MOMs) were synthesized and applied for pre‐concentration and determination of sodium valproate (Na‐VP) from biological samples, bound to the copper complex of 1,4‐phenylenedioxydiacetic acid under mild conditions. The channels of this sorbent provide high efficiency and also selectivity. The MOMs were structurally characterized using Fourier transform infrared and energy‐dispersive X‐ray spectroscopies, scanning electron microscopy and X‐ray diffraction, and they were found to have suitable features for quantification of Na‐VP using HPLC coupled with UV detection at λ = 215 nm. Moreover, the rate of adsorption is improved by ultrasonic power and the experimental data are best fitted according to Freundlich adsorption isotherm. According to the central composite design, the best experimental conditions are 280.0 μl, 3.0 min and 17.0 mg for volume of eluent, sonication time and sorbent mass respectively. Calibration plots show linear responses towards Na‐VP concentrations (0.4–18.0 μg ml?1), satisfactory limit of detection (0.06 μg ml?1, S/N = 3) and reasonable enrichment factor (70.58). The coefficient of variation values of both inter‐ and intra‐day analyses were less than 4.0%, indicating a candidate method for the determination of Na‐VP in human plasma with reasonable recovery and efficiency. 相似文献
933.
Oumaima Zidi Nessrine Souai Henda Raies Farhat Ben Ayed Amel Mezlini Sonia Mezrioui Fabrice Tranchida Jean-Marc Sabatier Amor Mosbah Ameur Cherif Laetitia Shintu Soumaya Kouidhi 《Molecules (Basel, Switzerland)》2021,26(8)
Breast cancer (BC) is the most common form of cancer among women worldwide. Despite the huge advancements in its treatment, the exact etiology of breast cancer still remains unresolved. There is an increasing interest in the role of the gut microbiome in modulating the anti-cancer therapeutic response. It seems that alteration of the microbiome-derived metabolome potentially promotes carcinogenesis. Taken together, metabolomics has arisen as a fascinating new omics field to screen promising metabolic biomarkers. In this study, fecal metabolite profiling was performed using NMR spectroscopy, to identify potential biomarker candidates that can predict response to neoadjuvant chemotherapy (NAC) for breast cancer. Metabolic profiles of feces from patients (n = 8) following chemotherapy treatment cycles were studied. Interestingly, amino acids were found to be upregulated, while lactate and fumaric acid were downregulated in patients under the second and third cycles compared with patients before treatment. Furthermore, short-chain fatty acids (SCFAs) were significantly differentiated between the studied groups. These results strongly suggest that chemotherapy treatment plays a key role in modulating the fecal metabolomic profile of BC patients. In conclusion, we demonstrate the feasibility of identifying specific fecal metabolic profiles reflecting biochemical changes that occur during the chemotherapy treatment. These data give an interesting insight that may complement and improve clinical tools for BC monitoring. 相似文献
934.
Magdalena Kdzierska Piotr Potemski Anna Drabczyk Sonia Kudacik-Kramarczyk Magdalena Gb Beata Grabowska Dariusz Mierzwiski Boena Tyliszczak 《Molecules (Basel, Switzerland)》2021,26(6)
Many investigations are currently being performed to develop the effective synthesis methodology of magnetic nanoparticles with appropriately functionalized surfaces. Here, the novelty of the presented work involves the preparation of nano-sized PEGylated Fe3O4@Ag particles, i.e., the main purpose was the synthesis of magnetic nanoparticles with a functionalized surface. Firstly, Fe3O4 particles were prepared via the Massart process. Next, Ag+ reduction was conducted in the presence of Fe3O4 particles to form a nanosilver coating. The reaction was performed with arabic gum as a stabilizing agent. Sound energy-using sonication was applied to disintegrate the particles’ agglomerates. Next, the PEGylation process aimed at the formation of a coating on the particles’ surface using PEG (poly(ethylene glycol)) has been performed. It was proved that the arabic gum limited the agglomeration of nanoparticles, which was probably caused by the steric effect caused by the branched compounds from the stabilizer that adsorbed on the surface of nanoparticles. This effect was also enhanced by the electrostatic repulsions. The process of sonication caused the disintegration of aggregates. Formation of iron (II, III) oxide with a cubic structure was proved by diffraction peaks. Formation of a nanosilver coating on the Fe3O4 nanoparticles was confirmed by diffraction peaks with 2θ values 38.15° and 44.35°. PEG coating on the particles’ surface was proven via FT-IR (Fourier Transform Infrared Spectroscopy) analysis. Obtained PEG–nanosilver-coated Fe3O4 nanoparticles may find applications as carriers for targeted drug delivery using an external magnetic field. 相似文献
935.
Yael Juarez-Martinez Dr. Pablo Labra-Vázquez Dr. Alejandro Enríquez-Cabrera Andrés F. Leon-Rojas Diego Martínez-Bourget Dr. Pascal G. Lacroix Marine Tassé Sonia Mallet-Ladeira Dr. Norberto Farfán Dr. Rosa Santillan Dr. Gabriel Ramos-Ortiz Dr. Jean-Pierre Malval Prof. Isabelle Malfant 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(62):e202201692
One monometallic and three bimetallic ruthenium nitrosyl (RuNO) complexes are presented and fully characterized in reference to a parent monometallic complex of formula [FTRu(bpy)(NO)]3+, where FT is a fluorenyl-substituted terpyridine ligand, and bpy the 2,2’-bipyridine. These new complexes are built with the new ligands FFT, TFT, TFFT, and TF-CC-TF (where an alkyne C≡C group is inserted between two fluorenes). The crystal structures of the bis-RuNO2 and bis-RuNO complexes built from the TFT ligand are presented. The evolution of the spectroscopic features (intensities and energies) along the series, at one-photon absorption (OPA) correlates well with the TD-DFT computations. A spectacular effect is observed at two-photon absorption (TPA) with a large enhancement of the molecular cross-section (σTPA), in the bimetallic species. In the best case, σTPA is equal to 1523±98 GM at 700 nm, in the therapeutic window of transparency of biological tissues. All compounds are capable of releasing NO⋅ under irradiation, which leads to promising applications in TPA-based drug delivery. 相似文献
936.
Manuela Simonato Francesca Ricci Chiara Catozzi Matteo Storti Sonia Giambelluca Alessio Correani Fabrizio Salomone Paola Cogo Virgilio Carnielli 《Journal of mass spectrometry : JMS》2022,57(2):e4808
Stable isotope tracing can be safely used for metabolic studies in animals and humans. The endogenous biosynthesis of lipids (lipogenesis) is a key process throughout the entire life but especially during brain and lung growth. Adequate synthesis of pulmonary surfactant lipids is indispensable for life. With this study, we report the use of deuterium-depleted water (DDW), suitable for human consumption, as metabolic precursor for lipogenesis. We studied 13 adult rabbits for 5 days. Four rabbits drank tap water (TW) and served as controls; in four animals, DDW was substituted to drinking water, whereas five drank deuterium-enriched water (DEW). After 5 days, a blood sample and a bronchoalveolar lavage (BAL) sample were collected. The 2H/1H (δ2H) of BAL palmitic acid (PA) desaturated phosphatidylcholine (DSPC), the major phospholipid of pulmonary surfactant, and of plasma water was determined by high-resolution mass spectrometry. We found that the δ2H values of DDW, DEW and TW were −984 ± 2‰, +757 ± 2‰ and −58 ± 1‰, respectively. After 5 days, plasma water values were −467 ± 87‰, +377 ± 56‰ and −53 ± 6‰, and BAL DSPC-PA was −401 ± 27‰, −96 ± 38‰ and −249 ± 9‰ in the DDW, DEW and TW, respectively. With this preliminary study, we demonstrated the feasibility of using DDW to label pulmonary surfactant lipids. This novel approach can be used in animals and in humans, and we speculate that it could be associated with more favourable study compliance than DEW in human studies. 相似文献
937.
Assem Ibrahim Bustamante Juan Carlos Trepode Sonia Valdivieso Yadira 《Algebras and Representation Theory》2021,24(5):1191-1220
Algebras and Representation Theory - The objective of this paper is to give a concrete interpretation of the dimension of the first Hochschild cohomology space of a cyclically oriented or tame... 相似文献
938.
André Raposo Moreira Dias Arianna Pina Amelia Dean Dr. Hans-Georg Lerchen Dr. Michele Caruso Dr. Fabio Gasparri Dr. Ivan Fraietta Dr. Sonia Troiani Dr. Daniela Arosio Prof. Dr. Laura Belvisi Dr. Luca Pignataro Dr. Alberto Dal Corso Prof. Dr. Cesare Gennari 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(7):1696-1700
This work takes advantage of one of the hallmarks of cancer, that is, the presence of tumor infiltrating cells of the immune system and leukocyte-secreted enzymes, to promote the activation of an anticancer drug at the tumor site. The peptidomimetic integrin ligand cyclo(DKP-RGD) was found to accumulate on the surface of αvβ3 integrin-expressing human renal cell carcinoma 786-O cells. The ligand was conjugated to the anticancer drug paclitaxel through a Asn-Pro-Val (NPV) tripeptide linker, which is a substrate of neutrophil-secreted elastase. In vitro linker cleavage assays and cell antiproliferative experiments demonstrate the efficacy of this tumor-targeting conjugate, opening the way to potential therapeutic applications. 相似文献
939.
Frontispiece: Synthesis of Meso‐Substituted Subphthalocyanine–Subporphyrin Hybrids: Boron Subtribenzodiazaporphyrins
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)
940.
Pauline Gualco Dr. Maxime Mercy Sonia Ladeira Dr. Yannick Coppel Dr. Laurent Maron Dr. Abderrahmane Amgoune Dr. Didier Bourissou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(35):10808-10817
Coordination of ambiphilic diphosphine–silane ligands [o‐(iPr2P)C6H4]2Si(R)F (R=F, Ph, Me) to AuCl affords pentacoordinate neutral silicon compounds in which the metal atom acts as a Lewis base. X‐ray diffraction analyses, NMR spectroscopy, and DFT calculations substantiate the presence of Au→Si interactions in these complexes, which result in trigonal‐bipyramidal geometries around silicon. The presence of a single electron‐withdrawing fluorine atom is sufficient to observe coordination of the silane as a σ‐acceptor ligand, provided it is positioned trans to gold. The nature of the second substituent at silicon (R=F, Ph, Me) has very little influence on the magnitude of the Au→Si interaction, in marked contrast to N→Si adducts. According to variable‐temperature and 2D EXSY NMR experiments, the apical/equatorial positions around silicon exchange in the slow regime of the NMR timescale. The two forms, with the fluorine atom in trans or cis position to gold, were characterized spectroscopically and the activation barrier for their interconversion was estimated. The bonding and relative stability of the two isomeric structures were assessed by DFT calculations. 相似文献