全文获取类型
收费全文 | 399篇 |
免费 | 12篇 |
专业分类
化学 | 285篇 |
晶体学 | 3篇 |
力学 | 4篇 |
数学 | 60篇 |
物理学 | 59篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 16篇 |
2021年 | 24篇 |
2020年 | 15篇 |
2019年 | 14篇 |
2018年 | 12篇 |
2017年 | 9篇 |
2016年 | 10篇 |
2015年 | 16篇 |
2014年 | 14篇 |
2013年 | 17篇 |
2012年 | 25篇 |
2011年 | 23篇 |
2010年 | 12篇 |
2009年 | 15篇 |
2008年 | 16篇 |
2007年 | 28篇 |
2006年 | 17篇 |
2005年 | 15篇 |
2004年 | 15篇 |
2003年 | 9篇 |
2002年 | 15篇 |
2001年 | 3篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 1篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 3篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有411条查询结果,搜索用时 15 毫秒
401.
The first four members of a new family of C(3v)-symmetrical "two-story" calix[6]aza-cryptands have been synthesized. These large funnel shaped aza-ligands are formed through introduction of three aromatic arms as spacers onto the small rim of a calix[6]arene and subsequently capped with the tripodal aza caps tacn [1,3,5-triazacyclononane] or tren [tris(aminoethyl)amine]. A key feature for an efficient final 1:1 macrocyclization appears to be an adequate geometrical fit between the extended calixarene scaffold and the aza caps. 相似文献
402.
Bege N Renette T Jansch M Reul R Merkel O Petersen H Curdy C Müller RH Kissel T 《Macromolecular bioscience》2011,11(7):897-904
The goal of this study was to investigate the suitability of poly(ethylene carbonate) (PEC) nanoparticles as a novel drug delivery system, fulfilling the requirements for a long circulation time. Particles were obtained with a narrow size distribution and nearly neutral zeta potential. Adsorption studies with human plasma proteins revealed that PEC nanoparticles bind much less proteins in comparison to polystyrene (PS) nanoparticles. Cell experiments with fluorescently labeled PEC showed no uptake of the nanoparticles by macrophages. These novel PEC nanospheres with their unique surface properties are a promising candidate for long circulating drug delivery systems in vivo. 相似文献
403.
Shoji M Kaniwa K Hiranuma Y Maselli O Mafuné F 《The journal of physical chemistry. A》2011,115(11):2148-2154
We investigated solvation structures of I(-) and Na(+) on an aqueous solution surface by photodetachment spectroscopy and mass spectrometry. An aqueous solution of NaI was introduced into the vacuum as a continuous liquid flow (liquid beam), and the liquid beam was irradiated with a UV laser pulse. The abundance of electrons emitted by the laser excitation was measured as a function of wavelength (photodetachment spectroscopy). For a concentrated aqueous solution of NaI, we observe an absorption peak at longer wavelengths than the charge-transfer-to-solvent band of I(-) in solution. This feature is assigned to the photoabsorption of I(-) at the surface. This finding indicates that when the concentration of NaI is high (>1.0 M), I(-) exists on the solution surface. The identity of the ion clusters ejected from the liquid beam following selective laser excitation of I(-) on the surface or I(-) inside the solution was revealed by mass spectrometry. The mass spectra show that Na rich clusters are formed when I(-) inside the solution is excited, whereas Na rich clusters are hardly formed by the excitation of surface I(-). These findings lead us to conclude that Na(+) does not exist on the surface of the NaI aqueous solution. 相似文献
404.
Huang used the methods of Rogers, Watson and Bressoud to derive some new modular relations involving the Göllnitz-Gordon functions. In this paper, using Ramanujan’s modular equations, we present a uniform method to prove these modular relations established by Huang. 相似文献
405.
Dr. Nicolas Menard Yohann Hériot Dr. Yves Le Mest Prof. Dr. Olivia Reinaud Dr. Nicolas Le Poul Dr. Benoît Colasson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(32):10611-10618
The conformation of copper “funnel” complexes that contains a coordinating appended arm can be electrochemically switched between endo, which corresponds to the self‐coordination of the arm through the cavity, and exo positions. This process, which is reminiscent of a cup‐and‐ball device, is activated by an exogenous ligand for complexes that contain a hydroxy‐terminated arm. The exchange is electrochemically triggered and is operated in either CuI or CuII redox states, depending on the exogenous ligand, that is, CO or n‐butylamine, respectively. 相似文献
406.
Periodica Mathematica Hungarica - Let $$\bar{p}(n)$$ denote the number of overpartitions of n. Recently, numerous congruences modulo powers of 2, 3 and 5 were established regarding $$\bar{p}(n)$$ .... 相似文献
407.
Fan JX Yang XX Song JZ Huang XM Cheng ZX Yao L Juba OS Liang Q Yang Q Odeph M Sun Y Wang Y 《Applied biochemistry and biotechnology》2011,164(7):1023-1036
The filamentous fungus Fusarium oxysporum is known for its ability to ferment xylose-producing ethanol. However, efficiency of xylose utilization and ethanol yield was low. In this study, the transaldolase gene from Saccharomyces cerevisiae has been successfully expressed in F. oxysporum by an Agrobacterium tumefaciens-mediated transformation method. The enzymatic activity of the recombinant fungus (cs28pCAM-Sctal4) was 0.195 times higher than that of the wild-type strain (cs28). The recombinant strain also exhibited a 28.83% increase in ethanol yield on xylose media compared to the parental strain. Enhanced ethanol production and a reduction in the biomass were observed during xylose fermentation. Ethanol yield from rice straw by simultaneous saccharification and fermentation with cs28pCAM-Sctal4 was 0.25 g?g?1 of rice straw. The transgenic strain of F. oxysporum cs28pCAM-Sctal4 might therefore have potential applications in industrial bioenergy production. 相似文献
408.
Teixeira Olivia Lacerda Pedro Froes Thamires Quadros Nonato Maria Cristina Castilho Marcelo Santos 《Journal of computer-aided molecular design》2021,35(8):871-882
Journal of Computer-Aided Molecular Design - Assessment of target druggability guided by search and characterization of hot spots is a pivotal step in early stages of drug-discovery. The raw output... 相似文献
409.
Olivia L. Lanier Joseph M. Ficarrotta Isaac Adjei Dayita Wable Camryn Lewis Christopher Nacea Blanka Sharma Jon Dobson Peter McFetridge 《Macromolecular bioscience》2021,21(1)
Bone loss through traumatic injury is a significant clinical issue. Researchers have created many scaffold types to mimic an extracellular matrix to provide structural support for the formation of new bone, however functional regeneration of larger scaffolds has not been fully achieved. Newer scaffolds aim to deliver bioactive molecules to improve tissue regeneration. To achieve a more comprehensive regenerative response, a magnetically triggerable polymeric microparticle platform is developed for the on‐demand release of a complex mixture of isolated human placental proteins. This system is composed of polycaprolactone (PCL) microparticles, encapsulating magnetic nanoparticles (MNPs), and placental proteins. When subjected to an alternating magnetic field (AMF), the MNPs heat and melt the PCL, enhancing the diffusion of proteins from microparticles. When the field is off, the PCL re‐solidifies. This potentially allows for cyclic drug delivery. Here the design, synthesis, and proof‐of‐concept experiments for this system are reported. In addition, it is shown that the proteins retain function after being magnetically released. The ability to trigger the release of complex protein mixtures on‐demand may provide a significant advantage with wounds where stagnation of healing processes can occur (e.g., large segmented bone defects). 相似文献
410.
Alvarenga Gabriel M. Palombarini Julio Gonçalves Rosana A. Berengue Olivia M. Nunes Ronaldo S. Santos Sydney F. Villullas Hebe M. Ciapina Eduardo G. 《Journal of Solid State Electrochemistry》2023,27(9):2465-2477
Journal of Solid State Electrochemistry - The aim of this work was to study the effect of a RuO2 support on the activity of Pd nanoparticles for formic acid oxidation, comparing the results with... 相似文献