全文获取类型
收费全文 | 1925篇 |
免费 | 34篇 |
国内免费 | 6篇 |
专业分类
化学 | 1225篇 |
晶体学 | 17篇 |
力学 | 25篇 |
数学 | 104篇 |
物理学 | 594篇 |
出版年
2023年 | 9篇 |
2022年 | 11篇 |
2021年 | 20篇 |
2020年 | 24篇 |
2019年 | 27篇 |
2018年 | 16篇 |
2017年 | 16篇 |
2016年 | 31篇 |
2015年 | 30篇 |
2014年 | 43篇 |
2013年 | 97篇 |
2012年 | 74篇 |
2011年 | 82篇 |
2010年 | 53篇 |
2009年 | 52篇 |
2008年 | 77篇 |
2007年 | 99篇 |
2006年 | 88篇 |
2005年 | 104篇 |
2004年 | 96篇 |
2003年 | 72篇 |
2002年 | 83篇 |
2001年 | 54篇 |
2000年 | 49篇 |
1999年 | 17篇 |
1998年 | 28篇 |
1997年 | 28篇 |
1996年 | 40篇 |
1995年 | 50篇 |
1994年 | 45篇 |
1993年 | 39篇 |
1992年 | 40篇 |
1991年 | 32篇 |
1990年 | 38篇 |
1989年 | 33篇 |
1988年 | 22篇 |
1987年 | 22篇 |
1986年 | 14篇 |
1985年 | 16篇 |
1984年 | 20篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 13篇 |
1980年 | 13篇 |
1979年 | 13篇 |
1978年 | 19篇 |
1977年 | 11篇 |
1976年 | 12篇 |
1974年 | 12篇 |
1973年 | 17篇 |
排序方式: 共有1965条查询结果,搜索用时 9 毫秒
61.
We herein report comparative analysis of two versions of the biosynthetic gene clusters of antimycins, a natural product family possessing up to 44 distinct entities. The biosynthetic pathway of antimycins is amenable to the high structural variation of the substrates, supported by successes in heterologous expression of the ant cluster and in fluorine incorporation. The latter facilitated the investigation of the structure-activity relationship into the usually invariable 3-formamidosalicylic acid moiety of the molecules. 相似文献
62.
63.
Masato Abe 《Tetrahedron letters》2010,51(15):2071-8391
Production of a wide variety of cardiolipin (CL) analogues is critical for studying molecular mechanism of diverse biological functions of CL in mitochondria. We describe a concise procedure for the synthesis of CL using a phosphoramidite approach, which allows for the production of diverse CL analogues bearing linoleic acid(s) at any position on the glycerol backbone. 相似文献
64.
65.
66.
Gunji Takahiro Toyota Kouichi Arai Kayo Abe Yoshimoto 《Journal of Sol-Gel Science and Technology》1997,10(2):139-152
Syntheses and characterization of polymetallosiloxanes by the non-hydrolysis sol-gel process using no metal alkoxides were investigated. The reaction of silicic acid (SA) with MCl4 (M = Ti, Zr) in the molar ratios SA/MCl4 = 0.5–3.0 using a tetrahydrofuran-methanol solvent formed polymetallosiloxane (PMS), which was insoluble in organic solvents regardless of the molar ratio. The PMS was isolated as esterified polymetallosiloxane by esterification with isopropyl alcohol for various periods, which were soluble in methanol, acetone, and tetrahydrofuran. The number average molecular weight was 1000–3200 for esterified polytitanosiloxane and 3400–11000 for esterified polyzirconosiloxane. Esterified polymetallosiloxanes had no melting point but decomposition point. The results of analytical data indicated that esterified polymetallosiloxane and/or polymetallosiloxane consisted of the main chain of Si–O–Si and Si–O–M linkage with the pendants of alkoxy, silanol, and chloro group. 相似文献
67.
Dr. Yuki Ohishi Kentaro Masuda Kazuki Kudo Prof. Dr. Hajime Abe Prof. Dr. Masahiko Inouye 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(2):785-793
Generally, cage-shaped hosts for saccharides can bind strongly to guest molecules because of the three-dimensional preorganized hydrogen-bonding sites. However, the preparation of cage molecules is often difficult because of the low yield of the macrocyclization step. Here, we report a three-arm-shaped molecule possessing pyridine-acetylene-phenol units as a new kind of host having a preorganized three-dimensional hydrogen-bonding site. This three-arm-shaped host was readily prepared compared to a cage-shaped analogue. This host associated with lipophilic glycosides to form chiral complexes, and the association constants were sufficiently high as to be comparable to those of the cage-shaped analogue. Furthermore, this host extracted native monosaccharides into a lipophilic solvent. 相似文献
68.
Ayumi Yoshida Hitoshi Yamauchi Hideki Sakai Norimichi Kawashima Masahiko Abe 《Colloids and surfaces. B, Biointerfaces》1997,8(6):191-342
Molecular interactions between lipid bilayers (liposomes) and chondroitin sulfate C (CS), a water soluble polymer, have been investigated in terms of zeta-potential, particle size, microscopic-viscosity, microscopic-polarity of liposomes and permeability of calcein. Microscopic morphology is dramatically changed by the addition of CS to the positively charged liposomes (Pos.L), while it is not changed by the addition to uncharged liposomes (Unc.L) or negatively charged liposomes (Neg.L). The absolute value of the particle size of Pos.L increases with the addition of CS, while the zeta- potential of Pos.L decreases. Permeability of Pos.L decreases with an increase in the concentration of CS. Phase transition temperature of Pos.L is changed after the addition of CS. These values, however, are not changed for the other liposomes by the addition of CS. The results of gel filtration chromatography show that CS is absorbed on the Pos.L surface. Microscopic viscosity is also increased by the addition of CS to Pos.L due to the adsorption of CS. 相似文献
69.
Haruki Inoue Yuga Yamashita Yoshiki Ozawa Toshikazu Ono Masaaki Abe 《Molecules (Basel, Switzerland)》2021,26(21)
Two hexanuclear paddlewheel-like clusters appending six carboxylic-acid pendants have been isolated with the inclusion of polar solvent guests: [Cu6(Hmna)6]·7DMF (1·7DMF) and [Ag6(Hmna)6]·8DMSO (2·8DMSO), where H2mna = 2-mercaptonicotininc acid, DMF = N,N’-dimethylformamide, and DMSO = dimethyl sulfoxide. The solvated clusters, together with their fully desolvated forms 1 and 2, have been characterized by FTIR, UV–Vis diffuse reflectance spectroscopy, TG-DTA analysis, and DFT calculations. Crystal structures of two solvated clusters 1·7DMF and 2·8DMSO have been unambiguously determined by single-crystal X-ray diffraction analysis. Six carboxylic groups appended on the clusters trap solvent guests, DMF or DMSO, through H-bonds. As a result, alternately stacked lamellar architectures comprising of a paddlewheel cluster layer and H-bonded solvent layer are formed. Upon UV illumination (λex = 365 nm), the solvated hexasilver(I) cluster 2·8DMSO gives intense greenish-yellow photoluminescence in the solid state (λPL = 545 nm, ΦPL = 0.17 at 298 K), whereas the solvated hexacopper(I) cluster 1·7DMF displays PL in the near-IR region (λPL = 765 nm, ΦPL = 0.38 at 298 K). Upon complete desolvation, a substantial bleach in the PL intensity (ΦPL < 0.01) is observed. The desorption–sorption response was studied by the solid-state PL spectroscopy. Non-covalent interactions in the crystal including intermolecular H-bonds, CH⋯π interactions, and π⋯π stack were found to play decisive roles in the creation of the lamellar architectures, small-molecule trap-and-release behavior, and guest-induced luminescence enhancement. 相似文献
70.