全文获取类型
收费全文 | 369篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
化学 | 273篇 |
晶体学 | 2篇 |
力学 | 8篇 |
数学 | 11篇 |
物理学 | 95篇 |
出版年
2023年 | 5篇 |
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 7篇 |
2019年 | 13篇 |
2018年 | 8篇 |
2017年 | 5篇 |
2016年 | 17篇 |
2015年 | 8篇 |
2014年 | 14篇 |
2013年 | 28篇 |
2012年 | 29篇 |
2011年 | 28篇 |
2010年 | 14篇 |
2009年 | 14篇 |
2008年 | 16篇 |
2007年 | 24篇 |
2006年 | 26篇 |
2005年 | 22篇 |
2004年 | 19篇 |
2003年 | 12篇 |
2002年 | 13篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1970年 | 2篇 |
排序方式: 共有389条查询结果,搜索用时 9 毫秒
101.
Photoacoustic (PA) responses from very-thin poly(methyl methacrylate) (PMMA) films were investigated at various lamination conditions. The PA signal increased when the dye-doped films were laminated up to five layers, but tended to saturate beyond five layers. When the blank films were superimposed on the dye-doped film, the signal became smaller. The signal was larger when the dye-doped film was arranged outermost in the laminated film assembly of dye-doped and blank films. The results imply the effect of film vibration on the PA response. 相似文献
102.
Yuji Iijima Yasushi Kamei Nami Kobayashi Junji Awaka Taku Iwasa Shuji Ebisu 《哲学杂志》2013,93(21):2521-2530
A new thiospinel CuCrZrS4 has been successfully synthesized by a solid-state chemical reaction. This CuCrZrS4 exhibits ferromagnetic properties below the Curie temperature at T c = 60 -2 K. The appearance of irreversible effect between field-cooled and zero-field-cooled magnetization is prominent below around 5 K in a magnetic field of less than 150 Oe. The ac susceptibility χAC shows a rapid decrease below about 10 K. This low magnetic-field behaviour indicates the existence of a re-entrant spin-glass phase below about 10 K. The dc magnetic susceptibility above 100 K shows Curie-Weiss behaviour with an effective magnetic moment of 3.61 μ B, which is a little less than the spin-only value of 3.87 μ B for the Cr3+ ion. The asymptotic Curie temperature θ P is approximately 65 K, which is a little higher than T c. The valence state is confirmed to be Cu+Cr3+Zr4+S4 2? on the basis of magnetic properties. The electrical resistivity ρ shows a semiconducting temperature dependence over the temperature range from 4.2 to 280 K with an activation energy of 6.84 210?3 eV in the higher temperature range from 50 to 283 K. 相似文献
103.
Taku Aiga Dr. Yoshiyuki Manabe Keita Ito Tsung-Che Chang Dr. Kazuya Kabayama Shino Ohshima Prof. Yoshie Kametani Ayane Miura Hiroto Furukawa Dr. Hiroshi Inaba Prof. Kazunori Matsuura Prof. Koichi Fukase 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(40):17858-17864
Co-assembling vaccines composed of a lipidated HER2-derived antigenic CH401 peptide and either a lipophilic adjuvant, Pam3CSK4, α-GalCer, or lipid A 506, were evaluated as breast cancer vaccine candidates. This vaccine design was aimed to inherit both antigen multivalency and antigen-specific immunostimulation properties, observed in reported self-adjuvanting vaccine candidates, by using self-assembly and adjuvant-conjugated antigens. Under vaccination concentrations, respective lipophilic adjuvants underwent co-assembly with lipidated CH401, which boosted the anti-CH401 IgG and IgM production. In particular, α-GalCer was responsible for the most significant immune activation. Therefore, the newly developed vaccine design enabled the optimization of adjuvants against the antigenic CH401 peptide in a simple preparatory manner. Overall, the co-assembling vaccine design opens the door for efficient and practical self-adjuvanting vaccine development. 相似文献
104.
Systematic Control of the Excited‐State Dynamics and Carrier‐Transport Properties of Functionalized Benzo[ghi]perylene and Coronene Derivatives 下载免费PDF全文
Sunao Hirayama Dr. Hayato Sakai Prof. Yasuyuki Araki Minako Tanaka Masaki Imakawa Prof. Takehiko Wada Prof. Taishi Takenobu Prof. Taku Hasobe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(29):9081-9093
A series of benzo[ghi]perylene (Bp) and coronene (Cor) derivatives substituted with electron‐withdrawing methoxycarbonyl (COOMe) or electron‐donating methoxyl (MeO) groups was synthesized. The electrochemical, spectroscopic, and photophysical properties of these compounds were investigated by cyclic voltammetry, steady‐state and time‐resolved spectroscopy, and quantum‐yield measurements. Introduction of suitable substituents onto the aromatic rings enabled control of electrochemical and spectroscopic behavior. Examination of excited‐state dynamics revealed that fluorescence quantum yields increased with increasing number of COOMe groups in both Bp and Cor derivatives, consistent with the findings of DFT calculations. Single‐crystal analysis allowed the performance of field‐effect transistors containing single crystals of the derivatives to be rationalized. 相似文献
105.
We disclosed a novel ‘racemization-free segment condensation’ based on the ‘O-acyl isopeptide method’ in which an N-segment including C-terminal O-acyl isopeptide structure with urethane-protected Ser/Thr residue was employed for the segment condensation, suggesting that the use of this method contributes to the effective convergent synthesis of long peptides/proteins. 相似文献
106.
Treatment of fluoroalkylated alkynes with various aryl halides and arylboronic acids in the presence of Pd(0) in DMF/H2O at 100 °C for 2 h led to the smooth three-component coupling reaction, the corresponding tetrasubstituted alkenes being obtained in high yields stereoselectively. 相似文献
107.
Taku Shibue Toshihiro Hirai Dr. Iwao Okamoto Dr. Nobuyoshi Morita Dr. Hyuma Masu Prof. Dr. Isao Azumaya Prof. Dr. Osamu Tamura 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(38):11678-11688
The total syntheses of tetrapeptides tubulysins D ( 1 b ), U ( 1 c ), and V ( 1 d ), which are potent tubulin polymerization inhibitors, are described. The synthesis of Tuv ( 2 ), an unusual amino acid constituent of tubulysins, includes an 1,3‐dipolar cycloaddition reaction of chiral nitrone D ‐ 6 derived from D ‐gulose with N‐acryloyl camphor sultam (?)‐ 9 employing the double asymmetric induction, whereas the synthesis of Tup ( 20 ), another unusual amino acid, involves a stereoselective Evans aldol reaction of (Z)‐boron enolate generated from (S)‐4‐isopropyl‐3‐propionyl‐2‐oxazolidinone with N‐protected phenylalaninal and a subsequent Barton deoxygenation protocol. We accomplished the total syntheses of tubulysins U ( 1 c ) and V ( 1 d ) by using these methodologies, in which the isoxazolidine ring was used as the effective protective group for γ‐amido alcohol functionality. Furthermore, to understand the structure‐activity relationship of tubulysins, we synthesized tubulysin D ( 1 b ) and cyclo‐tubulysin D ( 1 e ) from 2 ‐Me and 20 , and ent‐tubulysin D (ent‐ 1 d ) from ent‐ 2 ‐Me and ent‐ 20 , respectively. The preliminary results regarding their biological activities are also reported. 相似文献
108.
Matsukawa T Hasegawa H Shinohara Y Kobayashi J Shinohara A Chiba M Ichida K Yokoyama K 《Chemical & pharmaceutical bulletin》2010,58(12):1658-1660
The synthesis of D- and L-selenomethionine labeled with ?2Se and three deuteriums at Se-methyl group (D- and L-[2H?, ?2Se]selenomethionine) was described. D- And L-[2H?, ?2Se]selenomethionine were prepared by condensation of (R)- and (S)-2-amino-4-bromobutylic acid with lithium [2H?, ?2Se]methaneselenolate, which was prepared from metal (82)Se and [2H?]methyl iodide. The optical purities of D- and L-[2H?, ?2Se]selenomethionine were determined by HPLC with a chiral stationary phase column and were found more than 99% ee. The chemical ionization mass spectra showed that the molecular related ion for N-isobutyloxycarbonyl ethyl ester derivatives of [2H?, ?2Se]selenomethionine did not overlap with the m/z values known from that of non-labeled selenomethionine. 相似文献
109.
Okabayashi T Kurahara T Okabayashi EY Tanimoto M 《The Journal of chemical physics》2012,136(17):174311
Platinum monofluoride (PtF) and platinum monochloride (PtCl) were detected in the gas phase using a source-modulated microwave spectrometer. The PtF and PtCl radicals were generated in a free space cell using the sputtering reaction from a platinum sheet placed on the inner surface of a stainless steel cathode through a dc glow discharge plasma of CF(4) and Cl(2), respectively, diluted with Ar. Rotational transitions were measured in the region between 150 and 313 GHz. Rotational, centrifugal distortion, and several fine- and hyperfine-structure constants were determined by a least-squares analysis. The observed fine-structure spectral patterns indicate that both PtF and PtCl radicals have the (2)Π(3/2) electronic ground states, while the related cyanide PtCN and hydride PtH radicals have the (2)Δ(5/2) electronic ground states. 相似文献
110.
Yohsuke Yamamoto Shiro Matsukawa Shin-ya Furuta Kin-ya Akiba 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6-7):1375-1379
Solution and crystal structures of monocyclic pentacoordinate phosphoranes bearing two Martin ligands and two carbon substituents are described. When the two carbon substituents are different, relative apicophilicity of the two monodentate carbon substituents could be determined based on the equilibrium ratio of the pseudorotamers. In some cases, x-ray structural analysis could be carried out and the crystallized structure from CH 3 CN is consistent with the major pseudorotamer in solution (CD 3 CN). Furthermore, when the equilibrium ratio of pseudorotamers is almost unity, novel cocrystallization of two pseudorotamers in a single crystal was observed. 相似文献