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排序方式: 共有161条查询结果,搜索用时 15 毫秒
1.
Myung-Soon Lee 《Applied Surface Science》2006,252(14):5019-5025
We prepared high quality Au(1 1 1) film on Si wafer through the spin coating and thermal decomposition of a gold ink, spin-coated-and-fired (SCAF) Au film. The X-ray measurements, XRD and pole-figure analysis, showed that the SCAF Au film has a (1 1 1) out-of-plane orientation with a random in-plane orientation. In order to confirm the chemical activity of the SCAF Au film, we demonstrate the formation of patterned structures with the film by using soft lithography technique. The chemical activities of this physically stable SCAF Au film to the alkanethiols were at least equivalent those of physically deposited the Au films. The possibility of the mass production of micro patterned structure with the SCAF Au film was also demonstrated over the wide region on Si wafer by the microcontact lithography. These suggest that the Au film will help the easy fabrication of various nanosized devices on Si wafer and other substrates. 相似文献
2.
Kenji Hara Keiji Iwahashi Satoru Takakusagi Kohei Uosaki Masaya Sawamura 《Surface science》2007,601(22):5127-5132
Functionalization of self-assembled monolayer (SAM) of alkanethiolate with metal containing unit is one of the versatile methods to obtain functional surfaces such as heterogeneous catalysts. However, organic molecules that strongly bind to transition metals at SAM terminal are limited. Recently N-heterocyclic carbenes (NHCs) such as cyclic diaminocarbenes have emerged as strongly σ-donating ligands forming a robust bond with broad spectrum of transition metals. In the present study, for the purpose of establishment of a new robust basement for heterogeneous metal catalysts, a SAM of the alkanethiolate terminated with NHC-rhodium(I) complex moiety was prepared by utilizing a newly designed disulfide molecule bearing NHC-metal complex terminals. X-ray photoelectron spectroscopy (XPS) analysis and angle resolved XPS measurement revealed successful formation of the Rh-complex-terminated SAM on a gold substrate. Infrared reflection absorption spectroscopy (IRRAS) analysis suggested that the linker methylene chains connecting the rhodium complex moiety and the gold surface are in a loosely packed structure. This unique chemical species, NHC, would be a promising candidate as a basement for the construction of functional surface. 相似文献
3.
CUI Wei HUANG Lei LI Wei WANG Li-ping 《高等学校化学研究》2006,22(2):236-238
Introduction S Adenosylmethionine(SAM)isabiologicallyac tivecompoundwidelydistributedinthebodytissues andfluids.Itisinvolvedinanumberofbiochemical reactions.Asamethylgroupdonor,itisimportantin transmethylationreactions,whichcontributestothe synthesesofsuc… 相似文献
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A 3-amino-5-mercapto-1,2,4-triazole (TA) self-assembled monolayer-modified gold electrode (TA SAM/Au) is characterized by
X-ray photoelectron spectroscopy, A.C. impedance, cyclic voltammetry, chronoamperometry and chronocoulometry. The TA SAM/Au
exhibited good promotion of the electrochemical oxidation of dopamine. Some electrochemical parameters of dopamine such as
electron transfer number, exchange current density, standard heterogeneous rate constant, diffusion coefficient, etc., were
measured by different electrochemical methods. The peak currents of dopamine were linearly dependent on its concentration
in the range of 1.5 × 10−6–1.0 × 10−4 mol L−1, with a detection limit of 5.0 × 10−7 mol L−1. The oxidative peak potentials of dopamine and ascorbic acid were well separated at about 190 ± 10 mV in pH 2.0 BR buffers
at TA SAM/Au, the oxidation peak current increases approximately linearly with increasing concentration of both dopamine and
ascorbic acid in the concentration range of 9.98 × 10−6–4.54 × 10−4 mol L−1. It can be used for simultaneous determination of dopamine and ascorbic acid. 相似文献
7.
The synthesis of a family of N-mustard analogs of S-adenosyl-l-methionine (SAM) containing azides and alkynes at the N6-position of the adenosine base has been accomplished from commercially available inosine. Further biochemical analysis of these analogs indicates successful modification of pUC19 plasmid DNA in an enzyme-dependent fashion with DNA methyltransferases M.TaqI and M.HhaI. 相似文献
8.
Shusuke Sato Fumitaka Kudo Michel Rohmer Tadashi Eguchi 《Angewandte Chemie (International ed. in English)》2020,59(1):237-241
Adenosylhopane is a crucial intermediate in the biosynthesis of bacteriohopanepolyols, which are widespread prokaryotic membrane lipids. Herein, it is demonstrated that reconstituted HpnH, a putative radical S‐adenosyl‐l ‐methionine (SAM) enzyme, commonly encoded in the hopanoid biosynthetic gene cluster, converts diploptene into adenosylhopane in the presence of SAM, flavodoxin, flavodoxin reductase, and NADPH. NMR spectra of the enzymatic reaction product were identical to those of synthetic (22R)‐adenosylhopane, indicating that HpnH catalyzes stereoselective C?C formation between C29 of diploptene and C5′ of 5′‐deoxyadenosine. Further, the HpnH reaction in D2O‐containing buffer revealed that a D atom was incorporated at the C22 position of adenosylhopane. Based on these results, we propose a radical addition reaction mechanism catalyzed by HpnH for the formation of the C35 bacteriohopane skeleton. 相似文献
9.
Wenjuan Ji Xinjian Ji Qi Zhang Dhanaraju Mandalapu Zixin Deng Wei Ding Peng Sun Qi Zhang 《Angewandte Chemie (International ed. in English)》2020,59(23):8880-8884
Sulfur‐based homolytic substitution (SH reaction) plays an important role in synthetic chemistry, yet whether such a reaction could occur on the positively charged sulfonium compounds remains unknown. In the study of the anaerobic coproporphyrinogen III oxidase HemN, a radical S‐adenosyl‐l ‐methionine (SAM) enzyme involved in heme biosynthesis, we observed the production of di‐(5′‐deoxyadenosyl)methylsulfonium, which supports a deoxyadenosyl (dAdo) radical‐mediated SH reaction on the sulfonium center of SAM. The sulfonium‐based SH reactions were then investigated in detail by density functional theory calculations and model reactions, which showed that this type of reactions is thermodynamically favorable and kinetically competent. These findings represent the first report of sulfonium‐based SH reactions, which could be useful in synthetic chemistry. Our study also demonstrates the remarkable catalytic promiscuity of the radical SAM superfamily enzymes. 相似文献
10.
应用现场表面增强拉曼光谱和衰减全反射表面增强红外光谱初步研究了0.1mol·L-1HClO4溶液中Pt电极表面铁原卟啉(FePP)自组装单层的电化学和结构特性.以514nm波长为激发线,得到了增强因子约为40的粗糙Pt电极上FePP在不同电位下的表面增强拉曼光谱.分析0.5~-0.3V(SCE)区间内谱峰变化,得到近似的吸附等温式,由此可估算出Fe3+/Fe2+的式量电位大约为-0.2V.原位表面增强红外光谱的测试结果表明,FePP分子主要以斜立方式吸附在Pt膜电极表面,其中一个环外羧酸根与电极表面相接触,而另一羧酸基团以氢键与相邻的FePP分子相连.这样的吸附结构在-0.1~0.9V(SCE)的电位区间内并没有显著的变化. 相似文献