全文获取类型
收费全文 | 2152篇 |
免费 | 70篇 |
国内免费 | 6篇 |
专业分类
化学 | 1600篇 |
晶体学 | 20篇 |
力学 | 26篇 |
综合类 | 1篇 |
数学 | 134篇 |
物理学 | 447篇 |
出版年
2022年 | 13篇 |
2021年 | 17篇 |
2020年 | 28篇 |
2019年 | 39篇 |
2018年 | 35篇 |
2017年 | 16篇 |
2016年 | 39篇 |
2015年 | 54篇 |
2014年 | 46篇 |
2013年 | 106篇 |
2012年 | 102篇 |
2011年 | 135篇 |
2010年 | 78篇 |
2009年 | 52篇 |
2008年 | 126篇 |
2007年 | 138篇 |
2006年 | 120篇 |
2005年 | 92篇 |
2004年 | 81篇 |
2003年 | 83篇 |
2002年 | 90篇 |
2001年 | 55篇 |
2000年 | 46篇 |
1999年 | 23篇 |
1998年 | 16篇 |
1996年 | 20篇 |
1995年 | 13篇 |
1994年 | 24篇 |
1993年 | 24篇 |
1992年 | 25篇 |
1991年 | 25篇 |
1990年 | 24篇 |
1989年 | 17篇 |
1988年 | 23篇 |
1987年 | 31篇 |
1986年 | 24篇 |
1985年 | 35篇 |
1984年 | 23篇 |
1983年 | 16篇 |
1982年 | 19篇 |
1981年 | 14篇 |
1980年 | 15篇 |
1979年 | 20篇 |
1978年 | 24篇 |
1977年 | 20篇 |
1976年 | 19篇 |
1975年 | 25篇 |
1974年 | 22篇 |
1973年 | 18篇 |
1972年 | 10篇 |
排序方式: 共有2228条查询结果,搜索用时 15 毫秒
11.
Huricha Baigude Kaname Katsuraya Kohsaku Okuyama Kenichi Hatanaka Emi Ikeda Naokazu Shibata Toshiyuki Uryu 《Journal of polymer science. Part A, Polymer chemistry》2004,42(6):1400-1414
A novel sugar‐containing poly(ornithine) dendrimer is synthesized for possible antigen delivery and related applications. The dendrimer contains an ornithine dendron as interior scaffolding and oligosaccharides on the periphery, which provide an attachment site for a peptide antigen. Maltose or lactose is bound to both hemispherical and spherical poly(ornithine) dendrimer generation 3 (G3) by reductive amination between its reducing end and the peripheral amino group of the dendrimer using a borane‐pyridine complex in a buffer solution at 50 °C. The degree of substitution of sugar is changed by varying the molar ratio of sugar to dendrimer. When the surface of spherical poly(ornithine) dendrimer G3 is modified by binding β‐alanine to the 16 amino groups, highly substituted maltose‐ or lactose‐β‐alanine‐poly(ornithine) dendrimer G3 is obtained in high yield after 7 days of reaction. The structures of these sugar‐containing dendrimers are characterized by NMR and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry analyses. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1400–1414, 2004 相似文献
12.
Muon spin relaxation in zero field and longitudinal field was measured in single crystal samples of KH2PO4 (KDP) and KD2PO4 (DKDP) over a temperature range of 5 K to 300 K. At low temperatures, diamagnetic muons and muon substituted radicals with nuclear hyperfine coupling can be observed. For both KDP and DKDP, a minor change was observed in the dynamics of the muon below 140 K. Above 140 K, the mobility of the muon appears to increase and the diffusion rate becomes faster with increasing temperature. Only a small increase in the relaxation rate is observed in KDP due to the presence of theH
+, suggesting that the relaxation effects probably originate from the31P. 相似文献
13.
According to the concept of the recognized visual space of illumination (RVSI) the lightness of an object surface is perceived in relation to its conceptualized size. To prove this proposition the lightness of gray test patches was judged when they were located at various positions inside an illuminated space composed of two rooms in the depth direction from a subject. No retinal image arrangement was changed in the test patch and its immediate surroundings, but the front room had walls, floors and furniture lower in lightness by the amount of N1.5 than the back room to make the RVSI of the former smaller despite the illuminance in the entire space being the same. The results showed that the apparent lightness of the patches was perceived higher by amount of about 13 in L units for the N4 test patch and about 20 for N6 when the patches were located in the front room, in accordance with the prediction. It was stressed that the experiment of lightness judgment should be conducted in a three dimensional space rather than two dimensional plane as done by several investigators. 相似文献
14.
15.
16.
Adachi I Aihara H Dijkstra HB Enomoto R Fujii H Fujii K Fujii T Fujimoto J Fujiwara N Hayashii H Higashi S Iida N Imanishi A Ikeda H Ishii T Itoh R Iwasaki H Iwata S Kajikawa R Kamae T Kato S Kawabata S Kichimi H Kishida T Kobayashi M Kuroda S Kusuki N Maruyama A Maruyama K Masuda H Matsuda T Miyamoto A Morimoto T Nakamura K Nitoh O Noguchi S Ochiai F Okuno H Okusawa T Ohshima T Ozaki H Sato T Sai F Shimonaka J Shimozawa K Shirahashi A Sugahara R Sugiyama A Suzuki S Suwada T Takahashi K 《Physical review letters》1988,60(2):97-100
17.
T. Obara T. Iijima J. Komiyama S. Ikeda H. Ishikawa T. Nakagawa 《Journal of polymer science. Part A, Polymer chemistry》1978,16(9):2393-2402
From the analysis of the permeation of 35S labeled ethanesulfonic acid, through nylon-6 films sorption isotherms were obtained. The films are characterized by their largely different content of carboxyl and amino end groups. It was found that the shape of the isotherm depends on the molar ratio of the two end groups: an S-shape curve for the film containing the carboxyl end group larger than the amino end group and a Langmuir-type curve for the film containing comparable numbers of end groups. These results were explained by the McGregor-Harris theory in which the acid dissociation constants of the two end groups in nylon were estimated experimentally. 相似文献
18.
19.
Chang-Kyu Kim A. Takaku M. Yamamoto H. Kawamura K. Shiraishi Y. Igarashi S. Igarashi H. Takayama N. Ikeda 《Journal of Radioanalytical and Nuclear Chemistry》1989,131(1):131-137
Ammonium uranates (AU) obtained by the addition of aqueous NH4 OH to a solution of UO2 (NO3)2 or the equilibrium reaction of UO3 · 2H2 O with the vapour over concentrated NH4 OH have been studied by X-ray diffraction (XRD) analysis, diffuse reflectance Fourier transform infrared spectrometry (DR-FTIR) and chemical analysis. Ammonia can be present as either NH3 or NH
4
+
. For precipitates obtained at a pH of 3.7, ammonia in the form of NH3 is predominant. For ammonium uranate obtained by reaction over concentrated NH4OH, most of the ammonia is bonded as NH
4
+
. The reaction mechanism and structures of the products are also discussed. 相似文献
20.
Atsushi Ikeda Tsukasa HatanoToshifumi Konishi Jun-ichi KikuchiSeiji Shinkai 《Tetrahedron》2003,59(19):3537-3540
In a light-to-photocurrent conversion system based on a C60-porphyrin bilayer prepared by electrostatic alternate adsorption, porphyrin units in a porphyrin polymer have been isolated by cyclodextrin utilizing the host-guest interaction. In this system, a high quantum yield was achieved by suppression of self-quenching of porphyrin units. 相似文献