全文获取类型
收费全文 | 823篇 |
免费 | 20篇 |
国内免费 | 4篇 |
专业分类
化学 | 620篇 |
晶体学 | 2篇 |
力学 | 3篇 |
数学 | 26篇 |
物理学 | 196篇 |
出版年
2021年 | 6篇 |
2020年 | 6篇 |
2019年 | 6篇 |
2018年 | 4篇 |
2017年 | 7篇 |
2016年 | 9篇 |
2015年 | 5篇 |
2014年 | 18篇 |
2013年 | 34篇 |
2012年 | 35篇 |
2011年 | 47篇 |
2010年 | 22篇 |
2009年 | 24篇 |
2008年 | 60篇 |
2007年 | 42篇 |
2006年 | 63篇 |
2005年 | 49篇 |
2004年 | 48篇 |
2003年 | 21篇 |
2002年 | 25篇 |
2001年 | 28篇 |
2000年 | 16篇 |
1999年 | 18篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 10篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 9篇 |
1992年 | 5篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 7篇 |
1985年 | 15篇 |
1984年 | 22篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 12篇 |
1978年 | 11篇 |
1977年 | 7篇 |
1976年 | 15篇 |
1975年 | 7篇 |
1974年 | 12篇 |
1973年 | 8篇 |
1968年 | 3篇 |
排序方式: 共有847条查询结果,搜索用时 62 毫秒
31.
Prof. Jun Ishihara Fuma Usui Tomohiro Kurose Tomohiro Baba Yasunori Kawaguchi Yuki Watanabe Prof. Susumi Hatakeyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(6):1543-1552
The upper fragment of spirolides A and B, which are marine phycotoxins that exhibit strong antagonistic activities on nicotinic acetylcholine receptors, was constructed. The functionalized cyclohexene in spirolides was stereoselectively synthesized from the bicyclic lactone, which could be readily accessed by the Lewis acid template-catalyzed asymmetric Diels–Alder reaction of the pentadienol and methyl acrylate. 相似文献
32.
Abstract The present author investigated the structure-reactivity correlation in the reactions of amines with P-O-P bridged phosphonylating agent 1, diphosphonate. 相似文献
33.
We consider the problem of deducing the duality relation from the extended double shuffle relation for multiple zeta values. Especially we prove that the duality relation for double zeta values and that for the sum of multiple zeta values whose first components are 2’s are deduced from the derivation relation, which is known as a subclass of the extended double shuffle relation. 相似文献
34.
Norimasa Yoza Hisanobu Hirano Yoshinobu Baba Shigeru Ohashi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):605-608
Abstract Inorganic pyrophosphatase (EC 3. 6. 1. 1) drived the reaction of uridine 5′-triphosphate with glucose 1-monophosphate in the direction of uridine 5′-diphosphoglucose formation. 相似文献
35.
UV rays in sunlight are an important factor in the degradation of chemicals. In this study, we investigated the degradation of nonionic surfactants, nonylphenol polyethoxylates (NPEOs) with 10 or 70 ethylene oxide (EO) units using UVA, B and C, and their genotoxic change based on phosphorylation of histone H2AX (γ‐H2AX), a marker of DNA damage. NPEOs were degraded dependent on the energy of UV, that is, UVC having the highest energy was most effective, whereas UVA having the lowest energy caused little change. The EO side chain of NPEO(70) was broken near the benzene ring by UV, producing NPEOs with a shortened EO chain (around 10 units). The generation of γ‐H2AX reflected the pattern of degradation; shortening of the EO chain changed NPEO(70) into an inducer for γ‐H2AX, and degradation of NPEO(10) attenuated the genotoxicity. The γ‐H2AX generated by NPEO(10) and UV‐degraded NPEO(70) was independent of the cell cycle. The formation of DNA double strand breaks detected by gel electrophoresis was consistent with the results for γ‐H2AX. These results suggested that UV rays can make NPEOs harmless or genotoxic according to the degradation of the EO side chain, the effects being dependent on wavelength. 相似文献
36.
Yutaka Kubota Yuri Kaneda Kazuhiro Haraguchi Mirei Mizuno Hiroshi Abe Satoshi Shuto Takayuki Hamasaki Masanori Baba Hiromichi Tanaka 《Tetrahedron》2013
The key glycosyl donor for the target molecule 12 was prepared by two-step sequences; (1) acetalization of tert-butyldimethylsilyloxyacetaldehyde with 3-bromopropanediol, (2) DBN-initiated β-elimination of the resulting 2-(tert-butyldimethylsilyloxy)methyl-4-bromomethyl-1,3-dioxolane 11. Electrophilic glycosidation between 12 and silylated pyrimidine nucleobase proceeded efficiently to provide a mixture of β- and α-anomers of the respective glycosides 14 and 15. Tin radical-mediated reduction of the bromomethyl functional group of 14 and 15 gave protected 4′-C-methyl-dioxorane uracil- 16 and thymine nucleoside 17. The respective cytosine nucleoside 18 was synthesized from 16. De-silylation of 4′-methyl-1′,3′-dioxolane pyrimidine nucleosides 16–18 gave the target molecules. Evaluation of the anti-HIV-1 activity of the β- and α-anomers of the novel 4′-C-methyl-1′,3′-dioxolane nucleosides 22β,α–24β,α revealed that none of the nucleoside derivatives possess anti-viral activity against HIV-1 and show cytotoxicity against MT-4 cells at 100 μM. 相似文献
37.
F. Ditrói F. Tárkányi S. Takács A. Hermanne H. Yamazaki M. Baba A. Mohammadi 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(2):853-865
As a part of our series of studies on charged particle induced reactions on various target materials, proton induced excitation functions on natural cobalt have been determined by using the stacked-foil technique. In these measurements the radionuclides 55,56,57,58Co, 51Cr, 52,54,56Mn and 56,57Ni have been identified. For the above mentioned nuclides the cross-sections were derived from the measured activities and were compared with the literature data and with the results of EMPIRE code calculations and tabulated values in the TENDL 2011 library (based on TALYS code calculations). The agreement with previous measurements and with theoretical values was acceptable. 相似文献
38.
39.
Weerasak Chomkitichai Hathaithip Ninsonti Akira Baba Sukon Phanichphant Kazunari Shinbo Keizo Kato Futao Kaneko 《Surface and interface analysis : SIA》2014,46(9):607-612
We demonstrate the multiple plasmonic effect on the photocurrent properties of photoanodes containing Ag or Au nanoparticles (NPs) loaded onto titanium dioxide film (Ag–TiO2 or Au–TiO2) on Au grating surfaces. Ag–TiO2 or Au–TiO2 nanocomposite particles are prepared by a flame spray pyrolysis route. The structures and morphologies of the prepared products are characterized by high‐resolution transmission electron microscopy. The Ag–TiO2 or Au–TiO2 composite NPs are deposited by spin coating onto the Au grating surfaces. The photoanode electrode is a layered structure of blu‐ray disc‐recordable grating substrate/Au/Ag (or Au)–TiO2/dye/electrolyte/indium‐tin oxide. The plasmonic effect is induced when Ag or Au NPs are located within the propagating surface plasmon (SP) field on the Au grating surface. The short‐circuit photocurrent is increased by exciting the grating‐coupled propagating SP on the Au gratings and is further enhanced by positioning the Ag or Au NPs within the grating‐coupled SP field. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
40.
On the induced‐fit mechanism of substrate‐enzyme binding structures of nylon‐oligomer hydrolase 下载免费PDF全文
Takeshi Baba Ryuhei Harada Masayoshi Nakano Yasuteru Shigeta 《Journal of computational chemistry》2014,35(16):1240-1247
We present a detailed computational investigation of the induced‐fit motion in a nylon‐oligomer hydrolase (NylB) upon substrate binding. To this aim, we resort on the recently introduced parallel cascade selection molecular dynamics approach, allowing for an accelerated access to the set of conformational changes from an open‐ to a closed‐state structure to form the enzyme‐substrate complex in a specific induce‐fit mechanism. The structural investigation is quantitatively complemented by free energy analyses within the umbrella sampling algorithm accompanied by weighted histogram analysis. We find that the stabilization free energy is about 1.4 kcal/mol, whereas the highest free energy barrier to be overcome is about 2.3 kcal/mol. Conversely, the energetic contribution for the substrate binding is about 20 kcal/mol, as estimated from Generalized Born/Surface Area. This means that the open‐close induced‐fit motion could occur frequently once the substrate binds to the open state of NylB. © 2014 Wiley Periodicals, Inc. 相似文献