全文获取类型
收费全文 | 674篇 |
免费 | 23篇 |
国内免费 | 10篇 |
专业分类
化学 | 506篇 |
晶体学 | 3篇 |
力学 | 12篇 |
数学 | 57篇 |
物理学 | 129篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 10篇 |
2020年 | 11篇 |
2019年 | 12篇 |
2018年 | 7篇 |
2017年 | 6篇 |
2016年 | 21篇 |
2015年 | 15篇 |
2014年 | 18篇 |
2013年 | 39篇 |
2012年 | 44篇 |
2011年 | 49篇 |
2010年 | 21篇 |
2009年 | 31篇 |
2008年 | 57篇 |
2007年 | 47篇 |
2006年 | 45篇 |
2005年 | 42篇 |
2004年 | 38篇 |
2003年 | 39篇 |
2002年 | 34篇 |
2001年 | 9篇 |
2000年 | 9篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 10篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 1篇 |
1985年 | 7篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1978年 | 4篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1962年 | 1篇 |
1956年 | 3篇 |
1955年 | 2篇 |
排序方式: 共有707条查询结果,搜索用时 0 毫秒
151.
152.
The asymmetry and fringe inclination of the sawtooth-like waveform observed in the self-mixing signal obtained from a semiconductor laser with optical feedback enable the direction discrimination of line-of-sight motion of external target surfaces. We investigated the effects of linewidth enhancement factor and feedback strength on the asymmetry and the direction of fringe inclination of the signal by numerical simulations. For the first time, we show that direction of the fringe inclination is determined not only by the direction of the target motion but also by the value of the linewidth enhancement factor. 相似文献
153.
Osamu Tanaike Norihiro Kitada Hirofumi Yoshimura Hiroaki Hatori Kenichi Kojima Masaru Tachibana 《Solid State Ionics》2009,180(4-5):381-385
Lithium insertion behavior of carbon nanowall (CNW), which is a two-dimensional carbon nanostructures, was studied by cyclic voltammetry and charge/discharge measurements. It was found that CNW had reversible capacities of more than 200 mAh/g with stable charge/discharge potential like that of graphite even though the materials were produced at low temperature of 973 K. It was also found that CNW showed good responses of lithium insertion/extraction reaction because of their small and uniform particle size with well oriented graphene in nanometer scale. Heat treatment of CNW was found to purify the CNW from by-product amorphous carbon phase and the effect on their charge/discharge property was also clarified. 相似文献
154.
Hirofumi Tsumura 《Journal of Number Theory》2006,120(1):161-178
In the past decade, many relation formulas for the multiple zeta values, further for the multiple L-values at positive integers have been discovered. Recently Matsumoto suggested that it is important to reveal whether those relations are valid only at integer points, or valid also at other values. Indeed the famous Euler formula for ζ(2k) can be regarded as a part of the functional equation of ζ(s). In this paper, we give certain analytic functional relations between the Mordell-Tornheim double L-functions and the Dirichlet L-functions of conductor 3 and 4. These can be regarded as continuous generalizations of the known discrete relations between the Mordell-Tornheim L-values and the Dirichlet L-values of conductor 3 and 4 at positive integers. 相似文献
155.
ArF excimer laser irradiation can decompose water, and decomposed products contain highly reactive substrates, such as radicals. We propose cleaning using pure water with the aid of water decomposed products obtained by ArF excimer laser irradiation. In this study, the oxidation potential of decomposed products was estimated in metal etching. Then, cleaning of cutting oil was examined. The focal point of the lens used was set at the water surface. Specimens were aligned parallel to the laser beam, so that only decomposed products affected contaminants. As a result, decomposed products could not etch nickel and copper plates, but only zinc plates. Cutting oil was cleaned after 18 000 irradiation pulses. The range of the region cleaned was 5 mm around the focal point. 相似文献
156.
Clinical risk prediction formulas for cancer patients can be improved by dynamically updating the formulas by intermediate events, such as tumor progression. The increased accessibility of individual patient data (IPD) from multiple studies has motivated the development of dynamic prediction formulas accounting for between-study heterogeneity. A joint frailty-copula model for overall survival and time to tumor progression has the potential to develop a dynamic prediction formula of death from heterogenous studies. However, the process of developing, validating, and publishing the prediction formula is complex, which has not been sufficiently described in the literature. In this article, we provide a tutorial in order to build a web-based application for dynamic risk prediction for cancer patients on the basis of the R packages joint.Cox and Shiny. We demonstrate the proposed methods using a dataset of breast cancer patients from multiple clinical studies. Following this tutorial, we demonstrate how one can publish web applications available online, which can be manipulated by any user through a smartphone or personal computer. After learning this tutorial, developers acquire the ability to build an online web application using their own datasets. 相似文献
157.
Hiromi Kurokawa Atsushi Taninaka Toru Yoshitomi Hidemi Shigekawa Hirofumi Matsui 《Molecules (Basel, Switzerland)》2022,27(4)
The use of nanoparticles has been investigated as a new cancer treatment. These can induce specific cytotoxicity in cancer cells. In particular, Au nanoparticles (AuNPs) have unique characteristics. The maximum absorption spectrum of AuNPs can be adjusted to modify their size or shape to absorb near-infrared light that can penetrate into tissue without photodamage. Thus, the combination of AuNPs and near-infrared light can be used to treat cancer in deep-seated organs. To obtain effective cancer-specific accumulation of AuNPs, we focused on porphyrin and synthesized a porphyrin-attached Au compound: Au-HpD. In this study, we investigated whether Au-HpD possesses cancer-specific accumulation and cytotoxicity. Intracellular Au-HpD accumulation was higher in cancer cells than in normal cells. In order to analyze the cytotoxicity induced by Au-HpD, cancer cells and normal cells were co-cultured in the presence of Au-HpD; then, they were subjected to 870 nm laser irradiation. We observed that, after laser irradiation, cancer cells showed significant morphological changes, such as chromatin condensation and nuclear fragmentation indicative of cell apoptosis. This strong effect was not observed when normal cells were irradiated. Moreover, cancer cells underwent cell apoptosis with combination therapy. 相似文献
158.
A novel type of coupling reaction has been developed by the palladium-catalyzed reaction of propargylic oxiranes with arylboronic acids, in which anti-substituted 4-aryl-2,3-allenols were produced in a highly diastereoselective manner. A chiral-substituted allene has been synthesized from the reaction of a chiral propargylic oxirane without loss of the chirality. 相似文献
159.
Koji Shiba Hirofumi Hinode Masataka Wakihara 《Reaction Kinetics and Catalysis Letters》1998,64(2):281-288
Selective reduction of nitric oxide (NO) by ethene in the presence of excess oxygen was investigated using a silver supported
on TiO2 (Ag/TiO2) catalyst. Ag/TiO2 showed high catalytic activity for the reduction of NO to N2 and N2O. The activity for the reduction of NO to N2 and N2O was enhanced with an increase up to 3 wt.% Ag loading level. On increasing the concentration of ethene, the catalytic activity
for the reduction of NO to N2 and N2O was enhanced. The reduction of NO over Ag/TiO2 catalyst never proceeds without coexistent oxygen. 相似文献
160.