全文获取类型
收费全文 | 204篇 |
免费 | 14篇 |
国内免费 | 2篇 |
专业分类
化学 | 128篇 |
晶体学 | 4篇 |
力学 | 8篇 |
数学 | 32篇 |
物理学 | 48篇 |
出版年
2023年 | 5篇 |
2022年 | 1篇 |
2021年 | 6篇 |
2020年 | 8篇 |
2019年 | 6篇 |
2018年 | 10篇 |
2017年 | 3篇 |
2016年 | 9篇 |
2015年 | 6篇 |
2014年 | 14篇 |
2013年 | 18篇 |
2012年 | 22篇 |
2011年 | 15篇 |
2010年 | 20篇 |
2009年 | 14篇 |
2008年 | 17篇 |
2007年 | 12篇 |
2006年 | 2篇 |
2005年 | 5篇 |
2004年 | 6篇 |
2003年 | 4篇 |
2002年 | 3篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有220条查询结果,搜索用时 15 毫秒
1.
In the work described here, a biosensor was developed for the determination of sulfite in food. Malva vulgaris tissue homogenate containing sulfite oxidase enzyme was used as the biological material. M. vulgaris tissue homogenate was crosslinked with gelatin using glutaraldehyde and fixed on a pretreated Teflon membrane. Sulfite was enzymatically converted to sulfate in the presence of the dissolved oxygen, which was monitored amperometrically. Sulfite determination was carried out by standard curves, which were obtained by the measurement of consumed oxygen level related to sulfite concentration. Several operational parameters had been investigated: the amounts of plant tissue homogenate and gelatin, percentage of glutaraldehyde, optimum pH and temperature. Also, some characterization studies were done. There was linearity in the range between 0.2 and 1.8 mM at 35 °C and pH 7.5. The results of real sample analysis obtained with the biosensor agreed well with the enzymatic reference method using spectrophotometric detection. 相似文献
2.
H. Yücel H. Karadeniz M. A. Çetiner H. Demirel Ş. Turhan 《Journal of Radioanalytical and Nuclear Chemistry》2003,258(2):445-447
The sorption behavior of 235U fission fission products 99Mo and 132Te was studied through batch and dynamic experiments when they were dissolved in 1 to 7M HNO3 solutions. It was found that 99Mo is always totally adsorbed on hydrated SnO2, while 132Te is rather weakly adsorbed, therefore they can be separated from each other although 132Te in the solution still remains contaminated with other radionuclides as well as 99Mo does in the solid. 相似文献
3.
Yixuan Xie Siyu Chen Qiongyu Li Ying Sheng Michael Russelle Alvarez Joeriggo Reyes Gege Xu Kemal Solakyildirim Carlito B. Lebrilla 《Chemical science》2021,12(25):8767
A cross-linking method is developed to elucidate glycan-mediated interactions between membrane proteins through sialic acids. The method provides information on previously unknown extensive glycomic interactions on cell membranes. The vast majority of membrane proteins are glycosylated with complicated glycan structures attached to the polypeptide backbone. Glycan–protein interactions are fundamental elements in many cellular events. Although significant advances have been made to identify protein–protein interactions in living cells, only modest advances have been made on glycan–protein interactions. Mechanistic elucidation of glycan–protein interactions has thus far remained elusive. Therefore, we developed a cross-linking mass spectrometry (XL-MS) workflow to directly identify glycan–protein interactions on the cell membrane using liquid chromatography-mass spectrometry (LC-MS). This method involved incorporating azido groups on cell surface glycans through biosynthetic pathways, followed by treatment of cell cultures with a synthesized reagent, N-hydroxysuccinimide (NHS)–cyclooctyne, which allowed the cross-linking of the sialic acid azides on glycans with primary amines on polypeptide backbones. The coupled peptide–glycan–peptide pairs after cross-linking were identified using the latest techniques in glycoproteomic and glycomic analyses and bioinformatics software. With this approach, information on the site of glycosylation, the glycoform, the source protein, and the target protein of the cross-linked pair were obtained. Glycoprotein–protein interactions involving unique glycoforms on the PNT2 cell surface were identified using the optimized and validated method. We built the GPX network of the PNT2 cell line and further investigated the biological roles of different glycan structures within protein complexes. Furthermore, we were able to build glycoprotein–protein complex models for previously unexplored interactions. The method will advance our future understanding of the roles of glycans in protein complexes on the cell surface.The cell surface glycocalyx is highly interactive defined by extensive covalent and non-covalent interactions. A method for cross-linking and characterizing glycan–peptide interactions in situ is developed. 相似文献
4.
5.
Theoretical investigation on hydrazine (N2H4) adsorption on Ni(111) was done by using density functional theory. Stability and mechanism of hydrazine adsorption in anti, gauche and cis conformation on nickel surface were studied. Charge transfer between lone-pair orbital and d-band was found to stabilize the anti-conformation as the most stable conformation, in contrast with hydrazine in the gas-phase where gauche conformation is more favored. However, the derived anti-bonding state between adsorbate and substrate is partially occupied due to the spin-polarization in the local states near the Fermi level and thus contributes in weakening the bonding. The stable adsorption structure was further verified by comparing the calculated vibrational frequencies with HREELS measurement results. The results were found to be in agreement with experimental results. It was also found that the adsorption in cis-conformation is a transition state as evident from the existence of imaginary frequency on its lowest vibrational mode which belongs to NH2 torsional movement around N–N axis. 相似文献
6.
A novel synthetic method is introduced to prepare the biologically important montagnetol and erythrin compounds starting from a 1,3-benzodioxin-4-one, synthesized from commercially available orsellinic acid and erythritol. 相似文献
7.
制备了4-(5′-氨基萘-3′-磺酸)偶氮-(2″-N-(4苁,6苁-二氯-S-三嗪)苯-5″-(β-羟乙基砜硫酸酯)-2-甲基蒽醌(2a),4-(2′-氨基苯磺酸)偶氮-(2″-N-(4苁,6苁-二氯-S-三嗪)-3″-苯磺酸)-2-甲基蒽醌,4-(5′-氨基萘-3′-磺酸)偶氮-(2″-N-(4苁,6苁-二氯-S-三嗪)苯-5″-(β-羟乙基砜硫酸酯)-2-甲基蒽醌和4-(p-(β-羟乙基砜硫酸酯)偶氮-(2″-N-(4苁,6苁-二氯-S-三嗪)萘-5″-磺酸)-2-甲基蒽醌的FeIII,CoII金属配合物,并在安姆/沙门氏菌/微粒体致突变试验(Ames/Salmonella/Microsome Test)和大鼠胚胎中测定其致突变-畸变作用。不管是否使用代谢赋活剂S9mix,2a-Fe和2a-Co对TA98 and TA100菌株均无致突变-畸变作用。 相似文献
8.
Ayse Z. Aroguz Kemal Baysal Zelal Adiguzel Bahattin M. Baysal 《Applied biochemistry and biotechnology》2014,173(2):433-448
Hydrogels are attractive biomaterials for three-dimensional cell culture and tissue engineering applications. The preparation of hydrogels using alginate and gelatin provides cross-linked hydrophilic polymers that can swell but do not dissolve in water. In this work, we first reinforced pure alginate by using polyoxyethylene as a supporting material. In an alginate/PEO sample that contains 20 % polyoxyethylene, we obtained a stable hydrogel for cell culture experiments. We also prepared a stable alginate/gelatin hydrogel by cross-linking a periodate-oxidized alginate with another functional component such as gelatin. The hydrogels were found to have a high fluid uptake. In this work, preparation, characterization, swelling, and surface properties of these scaffold materials were described. Lyophilized scaffolds obtained from hydrogels were used for cell viability experiments, and the results were presented in detail. 相似文献
9.
Mohammad Kemal Agusta Melanie David Hiroshi Nakanishi Hideaki Kasai 《Surface science》2010,604(3-4):245-251
A theoretical study on the structure and adsorption mechanism of hydrazine (N2H4) on Ni(1 0 0) are presented. The hydrazine molecule was found to adsorb on the surface through one of its nitrogen atom in its anti-conformation. The charge transfer from hydrazine lone pair orbitals played a key role in the formation of the bonding. The mechanism involved in the bonding was found to reduce the necessity of hyper-conjugation interaction, that reduces the gauche effect found in hydrazine at the gas-phase. Upon adsorption to the surface, the reduced interaction resulted in the promotion of a more favored conformation through its anti-conformation. 相似文献
10.
Firat AK Karakaş HM Yakinci C Altinok T Alkan A Biçak U 《Magnetic resonance imaging》2004,22(9):1329-1332
Acute disseminated encephalomyelitis (ADEM) is an immune-mediated demyelinating disorder usually encountered in children or adolescents and characterized by multifocal neurological deficits of rapid onset. Typical target areas of demyelination include the corona radiata, centrum semiovale, periventricular white matter, cerebellar peduncles and brainstem. Involvement of deep gray matter nuclei is also frequent. We report a 6-year-old boy with ADEM who had only brainstem involvement. Serial magnetic resonance images representing the stage of disease and response to steroid treatment are presented. 相似文献