全文获取类型
收费全文 | 1797篇 |
免费 | 81篇 |
国内免费 | 3篇 |
专业分类
化学 | 1146篇 |
晶体学 | 14篇 |
力学 | 59篇 |
数学 | 132篇 |
物理学 | 530篇 |
出版年
2023年 | 25篇 |
2022年 | 39篇 |
2021年 | 54篇 |
2020年 | 55篇 |
2019年 | 49篇 |
2018年 | 40篇 |
2017年 | 36篇 |
2016年 | 67篇 |
2015年 | 42篇 |
2014年 | 86篇 |
2013年 | 116篇 |
2012年 | 114篇 |
2011年 | 142篇 |
2010年 | 100篇 |
2009年 | 90篇 |
2008年 | 113篇 |
2007年 | 77篇 |
2006年 | 69篇 |
2005年 | 81篇 |
2004年 | 48篇 |
2003年 | 40篇 |
2002年 | 26篇 |
2001年 | 21篇 |
2000年 | 20篇 |
1999年 | 26篇 |
1998年 | 10篇 |
1997年 | 14篇 |
1996年 | 16篇 |
1995年 | 13篇 |
1994年 | 14篇 |
1993年 | 20篇 |
1992年 | 12篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 10篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 11篇 |
1985年 | 14篇 |
1984年 | 16篇 |
1983年 | 13篇 |
1982年 | 11篇 |
1981年 | 10篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1975年 | 5篇 |
1974年 | 7篇 |
1973年 | 4篇 |
排序方式: 共有1881条查询结果,搜索用时 93 毫秒
61.
Kakali De Asoke Behera Indranil Banerjee Bharat Sarkar Santanu Ganguly Mridula Misra 《Journal of Radioanalytical and Nuclear Chemistry》2014,301(3):847-861
The aim of this study was to synthesis, a radiolabeled (99mTc) new somatostatin-analogue 6-hydrazinopyridine-3-carboxylic-acid (HYNIC)-Asn3-octreotate (99mTc-HYNIC-AATE), and to evaluate as a candidate for imaging somatostatin-receptor (SSTR)-positive tumors and also compare it with 99mTc-HYNIC-Tyr3-octreotide (99mTc-HYNIC-TOC). Synthesis was performed by Fmoc-solid-phase strategy and 99mTc labeled by SnCl2. Biodistribution and imaging properties of new radiopeptide were also studied in C6 tumor bearing rat. Radiolabeling was performed at high specific activities and it showed high binding-affinity for SSTR2. In biodistribution, radiopeptides have showed high and receptor-specific uptake in the SSTR2 positive organs, tumor with rapid renal excretion from non-target tissues. These results demonstrated that 99mTc-HYNIC-AATE is a new specific radioligand for scintigraphy of somatostatin-receptor-positive tumors. 相似文献
62.
Strong Stokes and Upconversion Luminescence from Ultrasmall Ln3+‐Doped BiF3 (Ln=Eu3+, Yb3+/Er3+) Nanoparticles Confined in a Polymer Matrix 下载免费PDF全文
Heavy metal fluorides like BiF3 as a host for lanthanide ions are of interest as bismuth is the only heavy metal that is nontoxic. In this work, we report the synthesis of highly water‐dispersible ultrasmall BiF3 nanoparticles about 6 nm in size within a poly(vinyl pyrrolidone) matrix by a hydrothermal method. Microscopy analysis reveals that the nanoparticles are well separated and confined within the polymer network. These nanoparticles were found to be excellent hosts for lanthanide (Ln3+) ions. Through suitable Ln3+ doping, BiF3 exhibits strong emissions in the visible region upon both UV and near infrared (NIR) excitations. The non‐toxicity of both bismuth and PVP can be advantageous for the potential use of BiF3 nanoparticles in drug delivery and bioimaging. 相似文献
63.
64.
Dr. Arijit Singha Hazari Shubhadeep Chandra Prof. Sanjib Kar Prof. Dr. Biprajit Sarkar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(24):e202104550
Metal complexes of multi-porphyrins and multi-corroles are unique systems that display a host of extremely interesting properties. Availability of free meso and β positions allow formation of different types of directly linked bis-porphyrins giving rise to intriguing optical and electronic properties. While the fields of metalloporphyrin and corroles monomer have seen exponential growth in the last decades, the chemistry of metal complexes of bis-porphyrins and bis-corroles remain rather underexplored. Therefore, the impact of covalent linkages on the optical, electronic, (spectro)electrochemical, magnetic and electrocatalytic activities of metal complexes of bis-porphyrins and -corroles has been summarized in this review article. This article shows that despite the (still) somewhat difficult synthetic access to these molecules, their extremely exciting properties do make a strong case for pursuing research on these classes of compounds. 相似文献
65.
66.
Chemistry of Heterocyclic Compounds - In recent years several important viral infections have emerged and antiviral chemotherapeutic agents are not sufficiently effective in clinic, leading to... 相似文献
67.
Julia Beerhues Maren Neubrand Dr. Sebastian Sobottka Dr. Nicolás I. Neuman Hannes Aberhan Shubhadeep Chandra Prof. Dr. Biprajit Sarkar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(21):6557-6568
Carbene-based radicals are important for both fundamental and applied chemical research. Herein, extensive electrochemical investigations of nine different 1,2,3-triazolylidene selenium adducts are reported. It is found that the half-wave potentials of the first reduction of the selones correlate with their calculated LUMO levels and the LUMO levels of the corresponding triazolylidene-based mesoionic carbenes (MICs). Furthermore, unexpected quasi-reversibility of the reduction of two triazoline selones, exhibiting comparable reduction potentials, was discovered. Through UV/Vis/NIR and EPR spectroelectrochemical investigations supported by DFT calculations, the radical anion was unambiguously assigned to be triazoline centered. This electrochemical behavior was transferred to a triazolylidene-type MIC-gold phenyl complex resulting in a MIC-radical coordinated AuI species. Apart from UV-Vis-NIR and EPR spectroelectrochemical investigations of the reduction, the reduced gold-coordinated MIC radical complex was also formed in situ in the bulk through chemical reduction. This is the first report of a monodentate triazolylidene-based MIC ligand that can be reduced to its anion radical in a metal complex. The results presented here provide design principles for stabilizing radicals based on MICs. 相似文献
68.
Inside Cover: Ruthenium Complexes of Tripodal Ligands with Pyridine and Triazole Arms: Subtle Tuning of Thermal,Electrochemical, and Photochemical Reactivity (Chem. Eur. J. 3/2014) 下载免费PDF全文
69.
Highly Luminescent Colloidal Eu3+‐Doped KZnF3 Nanoparticles for the Selective and Sensitive Detection of CuII Ions 下载免费PDF全文
Shyam Sarkar Manjunath Chatti Dr. Venkataramanan Mahalingam 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(12):3311-3316
This article describes a green synthetic approach to prepare water dispersible perovskite‐type Eu3+‐doped KZnF3 nanoparticles, carried out using environmentally friendly microwave irradiation at low temperature (85 °C) with water as a solvent. Incorporation of Eu3+ ions into the KZnF3 matrix is confirmed by strong red emission upon ultraviolet (UV) excitation of the nanoparticles. The nanoparticles are coated with poly(acrylic acid) (PAA), which enhances the dispersibility of the nanoparticles in hydrophilic solvents. The strong red emission from Eu3+ ions is selectively quenched upon addition of CuII ions, thus making the nanoparticles a potential CuII sensing material. This sensing ability is highly reversible by the addition of ethylenediaminetetraacetic acid (EDTA), with recovery of almost 90 % of the luminescence. If the nanoparticles are strongly attached to a positively charged surface, dipping the surface in a CuII solution leads to the quenching of Eu3+ luminescence, which can be recovered after dipping in an EDTA solution. This process can be repeated for more than five cycles with only a slight decrease in the sensing ability. In addition to sensing, the strong luminescence from Eu3+‐doped KZnF3 nanoparticles could be used as a tool for bioimaging. 相似文献
70.
Michael G. Sommer Petra Kureljak Dr. Damijana Urankar Dr. David Schweinfurth Nikolina Stojanović Dr. Martina Bubrin Dr. Martin Gazvoda Dr. Maja Osmak Prof. Dr. Biprajit Sarkar Prof. Dr. Janez Košmrlj 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(52):17296-17299
Azocarboxamide (azcH) has been combined for the first time with [Ru–Cym] to generate metal complexes with N,N‐ and N,O‐coordination mode, [(Cym)Ru(azc)Cl] and [(Cym)Ru(azcH)Cl]+[PF6]?. Geometric and electronic structures of the complexes are reported along with their in vitro activities against different tumour cell lines and preliminary results on solution chemistry. Compound [(Cym)Ru(azc)Cl] exhibited remarkable cytotoxic properties. It was cell‐type specific and had comparable IC50 values towards both cancer cells and their drug‐resistant subline. A tenfold increase in the sensitivity towards [(Cym)Ru(azc)Cl] was noted for the tumour cells with depleted intracellular glutathione (GSH) level, suggesting the essential role of GSH in cell response to this compound. 相似文献