全文获取类型
收费全文 | 1348篇 |
免费 | 63篇 |
国内免费 | 3篇 |
专业分类
化学 | 1138篇 |
晶体学 | 10篇 |
力学 | 18篇 |
数学 | 109篇 |
物理学 | 139篇 |
出版年
2023年 | 24篇 |
2022年 | 25篇 |
2021年 | 36篇 |
2020年 | 41篇 |
2019年 | 33篇 |
2018年 | 18篇 |
2017年 | 15篇 |
2016年 | 43篇 |
2015年 | 42篇 |
2014年 | 43篇 |
2013年 | 60篇 |
2012年 | 106篇 |
2011年 | 128篇 |
2010年 | 65篇 |
2009年 | 54篇 |
2008年 | 102篇 |
2007年 | 97篇 |
2006年 | 82篇 |
2005年 | 92篇 |
2004年 | 76篇 |
2003年 | 71篇 |
2002年 | 48篇 |
2001年 | 14篇 |
2000年 | 11篇 |
1999年 | 10篇 |
1998年 | 10篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 7篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1984年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1965年 | 1篇 |
1881年 | 1篇 |
1876年 | 1篇 |
排序方式: 共有1414条查询结果,搜索用时 15 毫秒
941.
Gold Nanorods with Phase‐Changing Polymer Corona for Remotely Near‐Infrared‐Triggered Drug Release
下载免费PDF全文
![点击此处可从《化学:亚洲杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ji Liu Christophe Detrembleur Bruno Grignard Marie‐Claire De Pauw‐Gillet Stéphane Mornet Mona Treguer‐Delapierre Yannick Petit Prof. Christine Jérôme Prof. Etienne Duguet 《化学:亚洲杂志》2014,9(1):275-288
Herein, we report a new drug‐delivery system (DDS) that is comprised of a near‐infrared (NIR)‐light‐sensitive gold‐nanorod (GNR) core and a phase‐changing poly(ε‐caprolactone)‐b‐poly(ethylene glycol) polymer corona (GNR@PCL‐b‐PEG). The underlying mechanism of the drug‐loading and triggered‐release behaviors involves the entrapment of drug payloads among the PCL crystallites and a heat‐induced phase change, respectively. A low premature release of the pre‐loaded doxorubicin was observed in PBS buffer (pH 7.4) at 37 °C (<10 % of the entire payload after 48 h). However, release could be activated within 30 min by conventional heating at 50 °C, above the Tm of the crystalline PCL domain (43.5 °C), with about 60 % release over the subsequent 42 h at 37 °C. The NIR‐induced heating of an aqueous suspension of GNR@PCL‐b‐PEG under NIR irradiation (802 nm) was investigated in terms of the irradiation period, power, and concentration‐dependent heating behavior, as well as the NIR‐induced shape‐transformation of the GNR cores. Remotely NIR‐triggered release was also explored upon NIR irradiation for 30 min and about 70 % release was achieved in the following 42 h at 37 °C, with a mild warming (<4 °C) of the surroundings. The cytotoxicity of GNR@PCL‐b‐PEG against the mouse fibroblastic‐like L929 cell‐line was assessed by MTS assay and good compatibility was confirmed with a cell viability of over 90 % after incubation for 72 h. The cellular uptake of GNR@PCL‐b‐PEG by melanoma MEL‐5 cells was also confirmed, with an averaged uptake of 1250(±110) particles cell?1 after incubation for 12 h (50 μg mL?1). This GNR@PCL‐b‐PEG DDS is aimed at addressing the different requirements for therapeutic treatments and is envisaged to provide new insights into DDS targeting for remotely triggered release by NIR activation. 相似文献
942.
Synergy,Compatibility, and Innovation: Merging Lewis Acids with Stereoselective Enamine Catalysis
下载免费PDF全文
![点击此处可从《化学:亚洲杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Andrea Gualandi Luca Mengozzi Claire M. Wilson Prof. Pier Giorgio Cozzi 《化学:亚洲杂志》2014,9(4):984-995
In recent years there has been an accelerated rate of development in the field of organocatalysis, with asymmetric organocatalysis now reaching full maturity. The invention of new organocatalytic reactions and the exploration of new concepts now appear in tandem with the application of organocatalytic techniques in the synthesis of natural products and active pharmaceutical ingredients (APIs). After a “golden rush” in organocatalysis, researchers are now starting to combine different methods, thereby taking advantage of the significant benefits of synergy. Metals are used in combination with organocatalytic processes, thus reaching complexity that is found in nature, where enzymes take advantage of the presence of certain metals to increase the arsenal of organic transformations available. In this Focus review, we illustrate the possibility of a “happy marriage” between Lewis acids and organocatalytic stereoselective processes. Questions have been raised about the combination of Lewis acids and organocatalysis owing to the presence of water and/or strong bases in these processes. Some Lewis acids have been shown to be compatible with organocatalysis and concepts relating to their use will be illustrated herein. To summarize the fruitful use of Lewis acids in stereoselective organocatalytic processes, we will draw attention to the advantages and selectivity achieved using this method. 相似文献
943.
Yulia B. Monakhova Rolf Godelmann Armin Hermann Thomas Kuballa Claire Cannet Hartmut Schäfer Manfred Spraul Douglas N. Rutledge 《Analytica chimica acta》2014
It is known that 1H NMR spectroscopy represents a good tool for predicting the grape variety, the geographical origin, and the year of vintage of wine. In the present study we have shown that classification models can be improved when 1H NMR profiles are fused with stable isotope (SNIF-NMR, 18O, 13C) data. Variable selection based on clustering of latent variables was performed on 1H NMR data. Afterwards, the combined data of 718 wine samples from Germany were analyzed using linear discriminant analysis (LDA), partial least squares-discriminant analysis (PLS-DA), factorial discriminant analysis (FDA) and independent components analysis (ICA). Moreover, several specialized multiblock methods (common components and specific weights analysis (ComDim), consensus PCA and consensus PLS-DA) were applied to the data. 相似文献
944.
Cécile Morel-Salmi Audrey Julia Claire Vigor Joseph Vercauteren 《Chromatographia》2014,77(13-14):957-961
Repeated chromatographic analyses of polyphenolic vine stalks extracts allowed us to note a huge adsorption difference on polyvinylidene fluoride (PVDF), between trans-resveratrol 1 and (+)-trans-ε-viniferin 2. We could optimize the conditions (solvent, saturation of the process), for this polymer to adsorb very selectively 2, with regard to the monomer 1 that remains in solution. Since membrane filters made of PVDF are quite often used for HPLC samples filtration, this observation prompted us to inform phytochemists studying plant stilbenoid contents. Based on this background information, we developed a straightforward and inexpensive enrichment process for either 1 and/or 2, from crude Vitis vinifera stalks extracts, allowing to get them in a pure form. Having at hand large amounts of these two pure compounds, they were tested and compared to a set of other relevant molecules for some biological properties: trans-ε-viniferin 2 was shown to be the most powerful tyrosinase inhibitor, among all samples tested. 相似文献
945.
Claire Simonneau Bérénice Leclercq Alexandra Mougel Eric Adriaenssens Charlotte Paquet Laurent Raibaut Nathalie Ollivier Hervé Drobecq Julien Marcoux Sarah Cianférani David Tulasne Hugo de Jonge Oleg Melnyk Jér?me Vicogne 《Chemical science》2015,6(3):2110-2121
The development of MET receptor agonists is an important goal in regenerative medicine, but is limited by the complexity and incomplete understanding of its interaction with HGF/SF (Hepatocyte Growth Factor/Scatter Factor). NK1 is a natural occurring agonist comprising the N-terminal (N) and the first kringle (K1) domains of HGF/SF. In the presence of heparin, NK1 can self-associate into a “head to tail” dimer which is considered as the minimal structural module able to trigger MET dimerization and activation whereas isolated K1 and N domains showed a weak or a complete lack of agonistic activity respectively. Starting from these structural and biological observations, we investigated whether it was possible to recapitulate the biological properties of NK1 using a new molecular architecture of isolated N or K1 domains. Therefore, we engineered multivalent N or K1 scaffolds by combining synthetic and homogeneous site-specifically biotinylated N and K1 domains (NB and K1B) and streptavidin (S). NB alone or in complex failed to activate MET signaling and to trigger cellular phenotypes. Importantly and to the contrary of K1B alone, the semi-synthetic K1B/S complex mimicked NK1 MET agonist activity in cell scattering, morphogenesis and survival phenotypic assays. Impressively, K1B/S complex stimulated in vivo angiogenesis and, when injected in mice, protected the liver against fulminant hepatitis in a MET dependent manner whereas NK1 and HGF were substantially less potent. These data reveal that without N domain, proper multimerization of K1 domain is a promising strategy for the rational design of powerful MET agonists. 相似文献
946.
Plaboni Hasan Stephen E. Potts Claire J. Carmalt Robert G. Palgrave Hywel O. Davies 《Polyhedron》2008
The Lewis acid/base adducts [MCl4{NH(R)(SiR′3)}] (M = Zr, Hf; R = tBu, R′ = Me; R = SiR′3 = SiMe3, SiMe2H) were synthesized by the 1:1 reaction of MCl4 with NH(R)(SiR′3) in dichloromethane solution at room temperature. The decomposition of [MCl4{NH(R)(SiR′3)}] proceeds with the elimination of R′3SiCl, as shown by thermogravimetric analysis. Pyrolysis of the compounds at 620 °C under inert conditions (N2, vacuum) afforded powders of composition [ClMN] or [Cl2MNH]. Preliminary low pressure chemical vapour deposition experiments show that [MCl4{NH(R)(SiR′3)}] deposits thin films of metal nitride contaminated with metal oxide. 相似文献
947.
948.
Is there any 12C/13C fractionation during starch remobilisation and sucrose export in potato tubers?
Florence Maunoury‐Danger Camille Bathellier Julien Laurette Chantal Fresneau Jaleh Ghashghaie Claire Damesin Guillaume Tcherkez 《Rapid communications in mass spectrometry : RCM》2009,23(16):2527-2533
The δ13C (carbon isotope composition) variations in respired CO2, total organic matter, proteins, sucrose and starch have been measured during tuber sprouting of potato (Solanum tuberosum) in darkness. Measurements were carried out both on tubers and on their growing sprouts for 23 days after the start of sprout development. Sucrose was slightly 13C‐depleted compared with starch in tubers, suggesting that starch breakdown was associated with a small isotope fractionation. In sprouts, all biochemical fractions including sucrose were 13C‐enriched compared with source tuber‐sucrose, suggesting that sucrose translocation from tuber to sprouts fractionated against 12C. However, both apparent fractionations were explained by the consumption of 13C‐depleted carbon for respiration or growth that enriched in the 13C sucrose molecules left behind. In addition, whole tuber sucrose is constantly composed of recent sucrose from starch breakdown and old sucrose associated with an inherited, slightly 13C‐depleted pool. We therefore conclude that any fractionation at either the starch breakdown or the sucrose translocation level is unlikely under our conditions. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
949.
Claire Seillan 《Tetrahedron letters》2009,50(6):630-632
A new preparation of N-substituted 1,3-diamino-4,6-diamidobenzenes has been achieved. This synthesis affords the first N-alkylamino derivatives for which a fine-tuning of the NR1R2 substituents should modify the reactivity of the amine functions. 相似文献
950.