全文获取类型
收费全文 | 1149篇 |
免费 | 31篇 |
国内免费 | 3篇 |
专业分类
化学 | 895篇 |
晶体学 | 12篇 |
力学 | 5篇 |
数学 | 38篇 |
物理学 | 233篇 |
出版年
2022年 | 11篇 |
2021年 | 14篇 |
2020年 | 23篇 |
2019年 | 22篇 |
2018年 | 15篇 |
2017年 | 6篇 |
2016年 | 24篇 |
2015年 | 21篇 |
2014年 | 19篇 |
2013年 | 71篇 |
2012年 | 47篇 |
2011年 | 56篇 |
2010年 | 21篇 |
2009年 | 41篇 |
2008年 | 56篇 |
2007年 | 54篇 |
2006年 | 58篇 |
2005年 | 63篇 |
2004年 | 72篇 |
2003年 | 74篇 |
2002年 | 47篇 |
2001年 | 52篇 |
2000年 | 36篇 |
1999年 | 17篇 |
1998年 | 6篇 |
1997年 | 17篇 |
1996年 | 13篇 |
1995年 | 5篇 |
1994年 | 7篇 |
1993年 | 17篇 |
1992年 | 13篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 14篇 |
1988年 | 17篇 |
1987年 | 11篇 |
1986年 | 12篇 |
1985年 | 14篇 |
1984年 | 21篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1978年 | 9篇 |
1977年 | 8篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1973年 | 7篇 |
1971年 | 3篇 |
排序方式: 共有1183条查询结果,搜索用时 468 毫秒
161.
This study proposes a prediction method for assessing the sound of a passing vehicle that is transmitted through a glass plate, which employs the vibro-acoustic finite-difference time-domain (FDTD) method. The noise that is transmitted through the glass in a building façade, which is affected by the sound-insulation characteristics of its glass plates, can have a psychological influence such as a sleep disorder on the residents. In this study, a prediction method for the spectral characteristics of the transmitting sound through glass plates is proposed. The sound-insulation characteristics of glass plates are obtained using a vibro-acoustic FDTD method, and are then synthesized with the sound of passing vehicles obtained by in situ measurement. Firstly, the sound transmitted through several kinds of glass plates is simulated using the proposed method. Then, in order to confirm the validity of this method, the simulated results are compared to measured sounds transmitted by passing vehicles into a room near the street. 相似文献
162.
Chie Hosokawa Yasutaka Sakamoto Suguru N. Kudoh Yoichiroh Hosokawa Takahisa Taguchi 《Applied Physics A: Materials Science & Processing》2013,110(3):607-612
We demonstrated the stimulation of neurons at a single-cell level in cultured neuronal network by a focused femtosecond laser. When the femtosecond laser was focused on a neuron loaded with a fluorescent calcium indicator, the fluorescence intensity immediately increased at the laser spot, suggesting that intracellular Ca2+ increases in the neuronal cell due to the femtosecond laser irradiation. The probability of Ca2+ elevation at the laser spot depended on the average laser power, irradiation time, and position of the focal point along the optical axis, indicating that the femtosecond laser activates neurons because of multiphoton absorption. Moreover, after laser irradiation of a single neuron cultured on multielectrode arrays, the evoked electrical activity of the neurons was demonstrated by electrophysiological systems, which concluded that the focused femtosecond laser could achieve stimulating a single neuron in a neuronal network with high spatial and temporal resolution. 相似文献
163.
164.
Longitudinal cooling forces have been measured for heavy ions from C6+ to U92+ at various energies from 50 to 360 MeV/u. Two experimental methods are described which offer the opportunity to measure the cooling force over the whole range of relative ion velocities from zero to 107 m/s. Measurements for various ion species are presented which show a pronounced deviation from the expected q2 scaling in the regime of low relative ion velocities. Further investigations concerning the influence of the magnetic field strength in the cooler revealed no significant influence. 相似文献
165.
Yuuki Hirayama Kentaro Yamaguchi Shigeru Sakamoto Michiko Iwamura 《Tetrahedron letters》2005,46(6):1027-1030
A new AB2 type building block for synthesis of dendritic compounds is made starting from Michael addition of 2 equiv of 3-hydroxyacetophenone to acrylate, followed by decarboxylation and deprotection of either carboxyl or hydroxyl protecting groups. [G1]-[G4] dendrons and [G2] dendrimer were synthesized by the reiterative [hydrogenolysis then DCC/DPTS coupling] sequence using a combination of convergent and divergent growth methods. 相似文献
166.
Syntheses of 3-substituted indazoles and benzoisoxazoles were efficiently accomplished with the aid of Pd-catalyzed intramolecular carbon-nitrogen and carbon-oxygen bond formations. The catalyst system described herein allows the cyclization to proceed under very mild conditions and thus could be applied to a wide range of substrates with acid- or base-sensitive functional groups. A total synthesis for the indazole ring-containing natural product nigellicine is also described. 相似文献
167.
168.
Yosiyuki Sakamoto Hirotugu Akaike 《Annals of the Institute of Statistical Mathematics》1978,30(1):185-197
Summary The purpose of the present paper is to propose a simple but practically useful procedure for the analysis of multidimensional
contingency tables of survey data. By the procedure we can determine the predictor on which a specific variable has the strongest
dependence and also the optimal combination of predictors. The procedure is very simply realized by the search for the minimum
of the statistic AIC within a set of models proposed in this paper. The practical utility of the procedure is demonstrated
by the results of some successful applications to the analysis of the survey data of the Japanese national character. The
difference between the present procedure and the conventional test procedure is briefly discussed.
The Institute of Statistical Mathematics 相似文献
169.
170.