全文获取类型
收费全文 | 372篇 |
免费 | 15篇 |
国内免费 | 3篇 |
专业分类
化学 | 286篇 |
力学 | 5篇 |
数学 | 16篇 |
物理学 | 83篇 |
出版年
2021年 | 3篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 10篇 |
2014年 | 6篇 |
2013年 | 26篇 |
2012年 | 24篇 |
2011年 | 20篇 |
2010年 | 11篇 |
2009年 | 8篇 |
2008年 | 17篇 |
2007年 | 27篇 |
2006年 | 21篇 |
2005年 | 21篇 |
2004年 | 15篇 |
2003年 | 12篇 |
2002年 | 24篇 |
2001年 | 11篇 |
2000年 | 5篇 |
1999年 | 8篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1987年 | 2篇 |
1985年 | 7篇 |
1984年 | 11篇 |
1983年 | 2篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 5篇 |
1973年 | 10篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 4篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有390条查询结果,搜索用时 15 毫秒
381.
Masamichi Igarashi 《Physics letters. [Part B]》1978,78(4):379-383
A full finite-range second order DWBA analysis is made for 48Ca(3He, t)48Sc at 23 MeV leading to the lowest 0+ ~ 7+ states of the [] configuration taking into account both 3Heαt and 3He dt two-step processes. The effect of the finite-range of the form factors strongly reduces the contribution of 3Heαt process and the nonorthogonality corrections drastically change the contribution of 3Hedt process. Because of these effects the contributions of both processes have about the same magnitude. 相似文献
382.
383.
Yoshiaki Hamada Masamichi Tsuboi Takahiro Matsuzawa Kaoru Yamanouchi Kozo Kuchitsu Yoshihiro Koga Shigeo Kondo 《Journal of Molecular Spectroscopy》1984,105(2):453-464
Infrared absorption spectrum of allylimine in the gas phase was measured for the first time. The spectrum consisted of two rotational isomers, cis and trans, around the CC bond. The relative population of the trans form was 70–80%, and the rest was for the cis form at room temperature. This intermediate molecule was produced by the thermal decomposition of diallylamine and by the isomerization of propargylamine. The vibrational assignments were made with the help of an ab initio MO calculation. The half-life in the absorption cell was about 20 min. 相似文献
384.
Yamasaki K Sakuma Y Sasaki J Matsumoto K Anzai K Matsuoka K Honda C Tsukada M Endo K Enomoto S 《Analytical and bioanalytical chemistry》2011,401(8):2531-2538
The excretion of essential trace elements, namely, Se, Sr, As, Mn, Co, V, Fe, and Zn into the bile of Se-deficient (SeD) Wistar
male rats was studied using the multitracer (MT) technique, and instrumental neutron activation analysis (INAA). Normal and
Se-control (SeC) rat groups were used as reference groups to compare the effects of Se levels on the behaviors of the essential
trace elements. The excretion (% dose) of Se, Sr, As, Mn, Co, and V increased with Se levels in the liver. The biliary excretion
of Mn and As dramatically enhanced for SeC rats compared with SeD rats, while that of V accelerated a little for SeC rats.
The radioactivity levels of 59Fe and 65Zn in the MT tracer solution were insufficient to measure their excretion into bile. The role of glutathione and bilirubin
for biliary excretion of the metals was discussed in relation to Se levels in rat liver. 相似文献
385.
Keisuke Ichihara Prof. Hidetoshi Kawai Yuka Togari Emi Kikuta Hitomi Kitagawa Prof. Seiji Tsuzuki Dr. Kenji Yoza Prof. Masamichi Yamanaka Prof. Kenji Kobayashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(11):3685-3692
Remarkably enhanced stability of the self‐assembled hydrogen‐bonded heterocapsule 1?2 by the encapsulation of 1,4‐bis(1‐propynyl)benzene 3 a was found with Ka=1.14×109 M ?1 in CDCl3 and Ka2=1.59×108 M ?2 in CD3OD/CDCl3 (10 % v/v) at 298 K. The formation of 3 a @( 1?2 ) was enthalpically driven (ΔH°<0 and ΔS°<0) and there was a unique inflection point in the correlation between ΔH° versus ΔS° as a function of polar solvent content. The ab initio calculations revealed that favorable guest–capsule dispersion and electrostatic interactions between the acetylenic parts (triple bonds) of 3 a and the aromatic inner space of 1?2 , as well as less structural deformation of 1?2 upon encapsulation of 3 a , play important roles in the remarkable stability of 3 a @( 1?2 ). 相似文献
386.
Masamichi Kobayashi Fumitoshi Kaneko 《Journal of Dispersion Science and Technology》2013,34(4-5):319-350
Molecular-level structures of lipids and related organic long-chain compounds were investigated by means of vibrational spectroscopic and X-ray diffraction methods. Various spectroscopic techniques applicable to structural studies of lipid systems were developed. Various types of solid-state phase transformations were found in even- and odd-numbered saturated fatty acids and their molecular mechanisms were considered. Crystal structures of some modifications of a series of cis-mono-unsaturated fatty acids were determined by the three-dimensional X-ray analysis and new types of molecular conformation as well as of subcell arrangement of the cis-mono-unsaturated acyl chains were found. An order-disorder type phase transformation accompanied with a partial melting at the interface of the molecular layers was found in some modifications of cis-mono-unsaturated fatty acids. Molecular conformations and crystal structures of the polymorphs of methyl oleate and triglycerides containing an oleoyl chain at the 2-position were investigated on the basis of the spectroscopic data. 相似文献
387.
Riichi Miyamoto Yukiko Ando Chie Kurusu Hong‐zhi Bai Kazuki Nakanishi Masamichi Ippommatsu 《Journal of separation science》2013,36(12):1890-1896
Reproducible fabrication of the hierarchically porous monolithic silica in a large volume exceeding 1000 mL has been established. By the hydrothermal enlargement of the fully accessible small pores to exceed 50 nm in diameter, the capillary force emerged on solvent evaporation was dramatically reduced, which allowed the preparation of crack‐free monoliths with evaporative solvent removal under an ambient pressure. The local temperature inhomogeneity within a reaction vessel in a large volume was precisely controlled to cancel the heat evolved by the hydrolysis reaction of tetramethoxysilane and that consumed to melt ice cubes dispersed in the solution, resulting in large monolithic silica pieces with improved structural homogeneity. Homogeneity of the pore structure was confirmed, both on macro‐ and mesoscales, using SEM, mercury intrusion, and nitrogen adsorption/desorption measurements. Furthermore, the deviations in chromatographic performance were examined by evaluating multiple smaller monolithic columns prepared from the monolithic silica pieces cut from different parts of a large monolith. All the daughter columns thus prepared exhibited comparable performances to each other to prove the overall homogeneity of the mother monolith. Preliminary results on high‐speed separation of peptides and proteins by the octadecylsilylated silica monolith of the above production have also been demonstrated. 相似文献
388.
The present status and key issues of surface passivation technology for III-V surfaces are discussed in view of applications to emerging novel III-V nanoelectronics. First, necessities of passivation and currently available surface passivation technologies for GaAs, InGaAs and AlGaAs are reviewed. Then, the principle of the Si interface control layer (ICL)-based passivation scheme by the authors’ group is introduced and its basic characterization is presented. Ths Si ICL is a molecular beam epitaxy (MBE)-grown ultrathin Si layer inserted between III-V semiconductor and passivation dielectric. Finally, applications of the Si ICL method to passivation of GaAs nanowires and GaAs nanowire transistors and to realization of pinning-free high-k dielectric/GaAs MOS gate stacks are presented. 相似文献
389.
Complexation of dihydroxyboryl compounds such as dihydroxyboryl phenylalanine and boric acid with polycarboxylic acids as well as polyols was studied by infrared spectroscopy and zone electrophoresis. By consulting the results obtained, gel formation of poly(vinyl alcohol) (PVA) in aqueous solutions of boric acids (BA) and borax was studied. The IR spectra of aqueous PVA-BA gels indicate that BA mainly assumes a planar triangle form, while the local conformation of PVA in the gel is different from that in aqueous solutions. 相似文献
390.