全文获取类型
收费全文 | 533篇 |
免费 | 9篇 |
国内免费 | 1篇 |
专业分类
化学 | 426篇 |
晶体学 | 7篇 |
力学 | 8篇 |
数学 | 11篇 |
物理学 | 91篇 |
出版年
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 9篇 |
2013年 | 22篇 |
2012年 | 26篇 |
2011年 | 40篇 |
2010年 | 18篇 |
2009年 | 23篇 |
2008年 | 36篇 |
2007年 | 46篇 |
2006年 | 43篇 |
2005年 | 32篇 |
2004年 | 33篇 |
2003年 | 28篇 |
2002年 | 20篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 8篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1975年 | 3篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1966年 | 3篇 |
排序方式: 共有543条查询结果,搜索用时 15 毫秒
91.
In this review, we describe the regulation of photomovement responses by phototropin and phytochrome photoreceptors. The blue light receptor phototropin mediates various photomovement responses such as phototropism, chloroplast movement and stomatal opening. In cryptogamic plants including ferns, mosses and green alga, red as well as blue light mediates phototropism and chloroplast movement. The red/far-red light reversibility suggests the involvement of phytochrome in these responses. Thereby, plant growth is presumably promoted by coordinating these photomovements to capture efficiently light for photosynthesis. 相似文献
92.
93.
Haizhou Wu Noriyuki Watanabe Yohichi Gohshi Ryuji Kotama 《Fresenius' Journal of Analytical Chemistry》1999,363(4):424-426
A mixture of 2-hydroxy-2-methylpropanoic acid (HIBA) and glycolic acid, with 1-octanesulfonate (OS) as hydrophobic ion proved
to be successful for the separation of rare-earth elements (REE). If the ratio of HIBA and glycolic acid is suitably adjusted,
it is possible to separate Y from Dy. The resolution of Y and Dy was further improved by controlling the concentration of
HIBA and glycolic acid. The technique was applied successfully to the separation and analysis of highly pure Y2O3 and Dy2O3.
Received: 30 June 1998 / Revised: 3 September 1998 / Accepted: 15 September 1998 相似文献
94.
Hydrogen removal from C-doped InGaAs grown on InP substrate by metalorganic chemical vapor deposition is discussed based on the dependence of hole concentration on various annealing conditions. It is revealed that the hydrogen removal rate becomes higher as the annealing temperature is higher and the activation energy of hydrogen removal is about 1.9 eV regardless of C-doped layer thickness. The hydrogen removal rate is also found to be inversely proportional to C-doped layer thickness, suggesting that the hydrogen removal reaction is mainly governed by hydrogen diffusion. 相似文献
95.
Processable polyaniline doped and complexed with dodecylbenzenesulfonic acid was obtained by one-step micellar chemical polymerization of aniline in the presence of dodecylbenzenesulfonic acid. Homogeneous transparent suspension could be made by dispersing processable polyaniline in m-cresol without any precipitation. Polyaniline composite film blended with polymethylmethacrylate (PMMA) exhibits relatively high levels of conductivity at low volume fractions of the polyaniline, while keeping good mechanical properties, equivalent to those of the PMMA. © 1998 John Wiley & Sons, Ltd. 相似文献
96.
Satoshi Goshima Masayuki Kanematsu Hiroshi Kondo Yusuke Tsuge Haruo Watanabe Yoshimune Shiratori Minoru Onozuka Noriyuki Moriyama 《Magnetic resonance imaging》2009,27(9):1230-1235
The purpose of this study was to compare observer interpreted steady-state coherent coronal images and gadolinium-enhanced axial images in terms of the detection and grading of esophageal varices. Magnetic resonance imaging (MRI) and gastrointestinal endoscopy were performed within 2 weeks in 90 patients with chronic liver damage, including 55 with untreated esophageal varices, for periodic screening purposes. Two blinded readers retrospectively reviewed T1- and T2-weighted images with gadolinium-enhanced (gadolinium image set) and steady-state coherent (coherent image set) images. Sensitivity for the detection of esophageal varices was higher (P<.001) in the gadolinium image set (76%) than in the coherent image set (35%); on the other hand, specificity was higher (P<.001) in the coherent image set (91%) than in the gadolinium image set (66%). Furthermore, area under the ROC curve was higher for the gadolinium image set (Az=0.823) than the coherent image set (Az=0.761) (P=.48). Moderate and weak positive correlations with endoscopic grades were found for the gadolinium image (r=0.48, P<.01) and coherent image sets (r=0.34, P=.018). The addition of steady-state coherent imaging to the current routine liver imaging protocol did not improve the detection or grading of esophageal varices, whereas gadolinium-enhanced imaging was found to be potentially valuable. Nevertheless, endoscopy was confirmed to be mandatory in patients with esophageal varices suspected by MRI of the liver. 相似文献
97.
Suzuki N Hashizume D Yoshida H Tezuka M Ida K Nagashima S Chihara T 《Journal of the American Chemical Society》2009,131(6):2050-2051
Low-valent zirconocene species reacted with 1,1,6,6-tetraalkyl-1,2,3,4,5-hexapentaenes to form both 1-zirconacyclopent-3-ynes and eta2-pi-coordinated complexes according to the alkyl groups (R) and the existence of the neutral ligand (L). Haptotropic interconvertion between these two complexes was observed. It was proposed that double insertion of isocyanide into the Zr-C bond of 1-zirconacyclopent-3-ynes takes place via the isocyanide adduct of the eta2-pi-complex as an intermediate. 相似文献
98.
Noriyuki Iwadate 《Journal of organometallic chemistry》2009,694(11):1713-19511
“Masked” areneboronic acids have been prepared by Ir-catalyzed C-H borylation of arenes. A [Ir(OMe)(cod)]2 complex with a DPPE ligand showed the highest catalytic activity in the C-H borylation of benzene at 80 °C. The reaction system can be applied to substituted arenes, including halogen-substituted arenes. 1,3-Dihalobenzenes undergo the C-H borylation at their 5-positions in a regioselective fashion, affording 3,5-dihaloareneboronic acid derivatives, which serve as useful coupling modules for the convergent dendrimer synthesis. 相似文献
99.
Acylglycerols (=Glycerides) from the Glandular Trichome Exudate on the Leaves of Paulownia tomentosa
Teigo Asai Noriyuki Hara Sawa Kobayashi Shiro Kohshima Yoshinori Fujimoto 《Helvetica chimica acta》2009,92(8):1473-1494
Chemical investigations of the glandular trichome exudates on the leaves of Paulownia tomentosa (Scrophulariaceae) led to the identification of the thirty acylglycerols (=glycerides) 1 – 30 , including five known ones ( 2, 3, 6, 9 , and 15 ) (Fig. 1). Spectroscopic analysis combined with GC/MS studies of the glycerides and the liberated fatty acids, in the form of trimethylsilyl ether derivatives and trimethylsilylated methyl esters, respectively, established that the constituents belonged to 1,3‐di‐O‐acetyl‐2‐O‐(fatty acyl)glycerols, 1‐O‐acetyl‐2‐O‐(fatty acyl)‐sn‐glycerols, and 2‐O‐(fatty acyl)glycerols, wherein the fatty acyl moiety was either an eicosanoyl or an octadecanoyl group bearing OH and/or AcO groups at the 3‐, 3,6‐, 3,7‐, 3,8‐, or 3,9‐positions. The 1‐O‐acetyl‐2‐O‐[(3R,6S)‐3‐(acetyloxy)‐6‐hydroxyeicosanoyl]‐sn‐glycerol ( 12 ; 20% of the total glycerides), 2‐O‐[(3R,8R)‐3,8‐bis(acetyloxy)eicosanoyl]glycerol ( 17 ; 14%), 2‐O‐[(3R,9R)‐3,9‐bis(acetyloxy)eicosanoyl]glycerol ( 18 ; 12%), and 2‐O‐[(3R)‐3‐(acetyloxy)eicosanoyl]glycerol ( 10 ; 12%) were relatively abundant constituents. The configurations of the stereogenic centers of the fatty acyl moieties were determined by 1H‐NMR analysis of the monoesters obtained from (R)‐ and (S)‐2‐(naphthalen‐2‐yl)‐2‐methoxyacetic acid ((R)‐ and (S)‐2NMA? OH and the hydroxy‐substituted fatty acid methyl esters (Fig. 2). The configuration at C(2) of the glycerol moiety of the 1‐O‐acetyl‐2‐O‐(fatty acyl)glycerols was determined to be (2S) by chemical conversion of, e.g., G‐2 (= 2 / 3 1 : 10) to (+)‐3‐O‐[tert‐butyl)diphenylsilyl]‐sn glycerol of known absolute configuration. 相似文献
100.
Cyril Martini Dr. Guillaume Poize Daniel Ferry Dr. Daiki Kanehira Noriyuki Yoshimoto Dr. Jörg Ackermann Dr. Frédéric Fages Prof. Dr. 《Chemphyschem》2009,10(14):2465-2470
We describe herein the design, synthesis and detailed structural characterization of hybrid 1D nanostructures. They are prepared by supramolecular self‐assembly of oligothiophene molecules on the surface of zinc oxide nanorods in solution at room temperature. Electronic absorption spectroscopy and X‐ray diffraction show that both organic and inorganic components in the coaxial p–n heterojunctions are crystalline. Especially, it is demonstrated that the organic compounds form a self‐assembled monolayer at the surface of the nanorods, which is not the case when zinc oxide quantum dots are instead used. As a result of their hybrid nature, the 1D nanostructures lead to ambipolar semiconducting nanostructured materials as active layers in field‐effect transistors. 相似文献