全文获取类型
收费全文 | 1156篇 |
免费 | 64篇 |
国内免费 | 4篇 |
专业分类
化学 | 984篇 |
晶体学 | 19篇 |
力学 | 10篇 |
数学 | 36篇 |
物理学 | 175篇 |
出版年
2023年 | 7篇 |
2022年 | 8篇 |
2021年 | 24篇 |
2020年 | 32篇 |
2019年 | 44篇 |
2018年 | 28篇 |
2017年 | 9篇 |
2016年 | 30篇 |
2015年 | 43篇 |
2014年 | 30篇 |
2013年 | 41篇 |
2012年 | 71篇 |
2011年 | 89篇 |
2010年 | 38篇 |
2009年 | 29篇 |
2008年 | 56篇 |
2007年 | 58篇 |
2006年 | 47篇 |
2005年 | 62篇 |
2004年 | 67篇 |
2003年 | 46篇 |
2002年 | 41篇 |
2001年 | 17篇 |
2000年 | 15篇 |
1999年 | 14篇 |
1997年 | 11篇 |
1996年 | 10篇 |
1994年 | 8篇 |
1993年 | 10篇 |
1992年 | 15篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1987年 | 7篇 |
1986年 | 14篇 |
1985年 | 8篇 |
1984年 | 22篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 10篇 |
1980年 | 14篇 |
1979年 | 13篇 |
1978年 | 9篇 |
1977年 | 16篇 |
1976年 | 13篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 7篇 |
1968年 | 5篇 |
排序方式: 共有1224条查询结果,搜索用时 234 毫秒
991.
Tomohito Naito Kohei Asai Tomoyuki Amano Masanobu Taniguchi 《Statistical Inference for Stochastic Processes》2010,13(3):163-174
In this paper, we propose a local Whittle likelihood estimator for spectral densities of non-Gaussian processes and a local
Whittle likelihood ratio test statistic for the problem of testing whether the spectral density of a non-Gaussian stationary
process belongs to a parametric family or not. Introducing a local Whittle likelihood of a spectral density f
θ
(λ) around λ, we propose a local estimator [^(q)] = [^(q)] (l){\hat{\theta } = \hat{\theta } (\lambda ) } of θ which maximizes the local Whittle likelihood around λ, and use f[^(q)] (l) (l){f_{\hat{\theta } (\lambda )} (\lambda )} as an estimator of the true spectral density. For the testing problem, we use a local Whittle likelihood ratio test statistic
based on the local Whittle likelihood estimator. The asymptotics of these statistics are elucidated. It is shown that their
asymptotic distributions do not depend on non-Gaussianity of the processes. Because our models include nonlinear stationary
time series models, we can apply the results to stationary GARCH processes. Advantage of the proposed estimator is demonstrated
by a few simulated numerical examples. 相似文献
992.
Masaki Takahashi Yusuke Murata Yuki Hakamata Kohei Suzuki Tetsuya Sengoku Hidemi Yoda 《Tetrahedron》2012,68(38):7997-8002
The first stereocontrolled synthesis of vittarilide-A and its C5-epimer was completed from d-glucuronolactone. Comparison with the spectroscopic properties reported for authentic material has given a clear indication as to the absolute stereochemistry of the natural vittarilide-A. 相似文献
993.
994.
Kensuke Kurihara Motoki Ueda Isao Hara Eri Hara Kohei Sano Akira Makino Eiichi Ozeki Fumihiko Yamamoto Hideo Saji Kaori Togashi Shunsaku Kimura 《Journal of nanoparticle research》2016,18(5):137
Polymeric micelles (Lactosome) in the size of 20–30 nm were labeled with radionuclides of 111In (111In-DOTA-Lactosome) for SPECT imaging and 90Y (90Y-DOTA-Lactosome) for β-ray irradiation for mammary tumor in mice. The tumor site at the femoral right leg grafted with 4T1 cells was clearly imaged at 24 h after the intravenous injection. Biodistribution revealed that the half-life time of 111In-DOTA-Lactosome was 11 h, which enabled the nanoparticle selectively accumulated in tumor site due to the enhanced permeability and retention (EPR) effect. The anti-tumor therapeutic effect of 90Y-DOTA-Lactosome was observed depending on the dose frequency and amount. Under the condition of the percutaneous ethanol injection treatment, the therapeutic effect of 90Y-DOTA-Lactosome was enhanced due to the super EPR effect. Owing to the super EPR effect, co-administration of 90Y-DOTA-Lactosome and DOXIL® inhibited the tumor growth during 15 days with their administrations. 相似文献
995.
Corrigendum: Electronic Transitions in Conformationally Controlled Tetrasilanes with a Wide Range of SiSiSiSi Dihedral Angles
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
996.
Nishikawa Kimi Bari Abdul Khan Abdul Jabbar Li Xin Menia Traci Semkow Thomas M. Lin Zhichao Healey Stephanie 《Journal of Radioanalytical and Nuclear Chemistry》2017,314(2):859-870
Journal of Radioanalytical and Nuclear Chemistry - We have developed a method of food sample preparation for gamma spectrometry involving the use of tetramethylammonium hydroxide (TMAH) and/or... 相似文献
997.
998.
Asymmetric Total Synthesis of Heronamides A–C: Stereochemical Confirmation and Impact of Long‐Range Stereochemical Communication on the Biological Activity
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Prof. Dr. Naoki Kanoh Shunya Itoh Kohei Fujita Dr. Kohei Sakanishi Ryosuke Sugiyama Yuta Terajima Prof. Dr. Yoshiharu Iwabuchi Prof. Dr. Shinichi Nishimura Prof. Dr. Hideaki Kakeya 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(25):8586-8595
Heronamides are biosynthetically related metabolites isolated from marine‐derived actinomycetes. Heronamide C shows potent antifungal activity by targeting membrane phospholipids possessing saturated hydrocarbon chains with as‐yet‐unrevealed modes of action. In spite of their curious hypothesized biosynthesis and fascinating biological activities, there have been conflicts in regard to the reported stereochemistries of heronamides. Here, we describe the asymmetric total synthesis of the originally proposed and revised structures of heronamide C, which unambiguously confirmed the chemical structure of this molecule. We also demonstrated nonenzymatic synthesis of heronamides A and B from heronamide C, which not only proved the postulated biosynthesis, but also confirmed the correct structures of heronamides A and B. Investigation of the structure–activity relationship of synthetic and natural heronamides revealed the importance of both long‐range stereochemical communication and the 20‐membered macrolactam ring for the biological activity of these compounds. 相似文献
999.
1000.
(E)-1-Alkenylsilanes with an amino or an alkoxy group on silicon can be conveniently synthesized by regioselective coupling of a potassium reagent derived from an allyl(amino)silane with alkyl halides. 相似文献