全文获取类型
收费全文 | 1014篇 |
免费 | 30篇 |
国内免费 | 5篇 |
专业分类
化学 | 825篇 |
晶体学 | 7篇 |
力学 | 17篇 |
数学 | 63篇 |
物理学 | 137篇 |
出版年
2023年 | 7篇 |
2022年 | 10篇 |
2021年 | 14篇 |
2020年 | 17篇 |
2019年 | 17篇 |
2018年 | 15篇 |
2017年 | 15篇 |
2016年 | 27篇 |
2015年 | 23篇 |
2014年 | 27篇 |
2013年 | 54篇 |
2012年 | 62篇 |
2011年 | 78篇 |
2010年 | 34篇 |
2009年 | 33篇 |
2008年 | 69篇 |
2007年 | 86篇 |
2006年 | 76篇 |
2005年 | 64篇 |
2004年 | 58篇 |
2003年 | 50篇 |
2002年 | 47篇 |
2001年 | 15篇 |
2000年 | 10篇 |
1999年 | 10篇 |
1998年 | 12篇 |
1997年 | 8篇 |
1996年 | 7篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1956年 | 1篇 |
排序方式: 共有1049条查询结果,搜索用时 0 毫秒
51.
Yuichi Tominaga Takuya Kubo Kenji Sueyoshi Ken Hosoya Koji Otsuka 《Journal of polymer science. Part A, Polymer chemistry》2013,51(15):3153-3158
To synthesize the novel molecular‐ and pH‐stimulus‐responsive hydrogel, we prepared poly(ethylene glycol)‐based hydrogel containing ionic groups. We evaluated the fundamental swelling/shrinking properties of the hydrogels synthesized by various conditions. Decreasing the molecular weight of a crosslinker provided the increasing of the equilibrium swelling ratio. Also, the equilibrium swelling ratio was changed by the introduction of functional ionic monomers and its compositions. Furthermore, the swelling/shrinking behaviors of the hydrogels were affected by the environmental condition of aqueous solution, in fact the hydrogels were considerably shrunk (to one‐fifth volume) using a di‐ionic solute in the aqueous solution through the ionic interactions between the hydrogel and the solutes. Additionally, the specific shrinking to diamine compounds was also observed in response to pH change. These results clearly show the swelling/shrinking responsibility of the hydrogels toward the molecular recognitions and its pH conditions. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3153–3158 相似文献
52.
Understanding the quantitative analysis of the transition adsorption structures of molecules on single‐walled carbon nanotubes (SWNTs) is of importance from the point of view of both fundamental science and applications of nanotubes. Absorption spectroscopy reveals that two different equilibrium states are existent for the exchange reaction of sodium cholate (SC) and oligo‐DNA (single‐stranded 20‐mer cytosine) on SWNTs. This is derived from the transitions of the adsorption structures of different chirality‐types of SWNTs and SC/DNA at certain SC concentrations below the critical micelle concentration of SC. 相似文献
53.
Alkylation of cyclohexenyl monoacetate 1 with R2Cu(CN)(MgCl)2 or RMgBr/CuCN (cat.) in Et2O produced trans 1,2-isomers 4, while arylation and alkenylation of 1 was accomplished with lithium borates 5 and a nickel cat. to afford trans 1,4-isomers 3 selectively. Furthermore, several transformations of the products were carried out to demonstrate synthetic advantages of the present reactions. 相似文献
54.
55.
Prof. Dr. Yasuchika Hasegawa Takafumi Matsui Dr. Yuichi Kitagawa Dr. Takayuki Nakanishi Dr. Tomohiro Seki Prof. Dr. Hajime Ito Prof. Dr. Yuta Nakasaka Prof. Dr. Takao Masuda Prof. Dr. Koji Fushimi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(53):12308-12315
Oxygen-sensitive and near-infrared (NIR) luminescent YbIII coordination polymers incorporating ligands based on pyrene derivatives were synthesized: YbIII–TBAPy and YbIII–TIAPy (TBAPy: 1,3,6,8-tetrakis(p-benzoate)pyrene; TIAPy: 1,3,6,8-tetrakis(3,5-isophthalic acid)pyrene). The coordination structures of these materials have been characterized by means of electrospray ionization mass spectrometry, X-ray diffraction analysis, and thermogravimetric analysis. Moreover, the porous structure of YbIII–TIAPy has been evaluated by measuring its N2 adsorption isotherm. The NIR luminescence properties of YbIII–TBAPy and YbIII–TIAPy have been examined by acquiring emission spectra and determining emission lifetimes under air or argon and in vacuo. YbIII–TIAPy exhibited high thermal stability (with a decomposition temperature of 400 °C), intense luminescence (with an emission quantum yield under argon of 6.6 %), and effective oxygen-sensing characteristics. These results suggest that NIR luminescent YbIII coordination polymers prepared using pyrene derivatives could have applications in novel thermo-stable oxygen sensors. 相似文献
56.
Kentaro Matsumoto Masayoshi Takayanagi Yuichi Suzuki Nobuaki Koga Masataka Nagaoka 《Journal of computational chemistry》2019,40(2):421-429
We have realized the microscopic simulation of olefin polymerization, that is, the simulation of the catalytic polymerization (CP) reaction system composed of (pyridylamido)hafnium(IV) complex as the catalyst. For this purpose, we adopted Red Moon (RM) method, a novel molecular simulation method to simulate the complex reaction system. First, according to the previous research, with the help of the QM calculation, we proposed a model system and elementary processes and explained the theoretical treatment of the simulation by the RM method (the RM simulation). In addition, we also proposed a macroscopic simulation based on chemical kinetics simulation. Then, we performed two simulations and compared them in terms of the effective time evolution of the three macroscopic physical quantities, the number-average molecular weight Mn , the mass-average molecular weight Mw , and the molar-mass dispersity ĐM . The comparison showed that the two simulations are in quantitative or partially qualitative agreement with each other. Therefore, it is concluded that the RM simulation could not only simulate the CP reaction process microscopically, but also it is connected essentially to reproduce the time evolution of the macroscopic physical quantities on the basis of its microscopic simulation data. © 2018 Wiley Periodicals, Inc. 相似文献
57.
Yuichi Komazaki Masashi Hiratsuka Yasushi Narita S. Tanaka Tomio Fujita 《Analytical and bioanalytical chemistry》1999,363(7):686-695
An automated continuous measurement system for the monitoring of formaldehyde (HCHO) and acetaldehyde (CH3CHO) in the urban atmosphere was developed by using an annular diffusion scrubber in conjunction with a high-performance liquid chromatograph (HPLC). With this technique, atmospheric HCHO and CH3CHO were effectively collected by the annular diffusion scrubber which consists of a porous polytetrafluoroethylene (PTFE) tube disposed concentrically within a Pyrex-glass tube and a scrubbing solution. 2,4-Dinitrophenylhydrazine (DNPH) was selected as the scrubbing solution for collecting HCHO and CH3CHO, which are derivatized to 2,4-dinitrophenylhydrazone-formaldehyde (DNPH-HCHO) and 2,4-dinitrophenylhydrazone-acetaldehyde (DNPH-CH3CHO), respectively. An aliquot of the sample solution was automatically injected into an HPLC equipped with a semi-micro ODS column and a UV-VIS detector for separating and determining DNPH-HCHO and DNPH-CH3CHO. All the operations are sequenced by a programmable controller, and automated continuous measurements are performed with a typical temporal resolution of 1 h. The collection efficiencies of HCHO and CH3CHO were about 97% and 93%, respectively, at an air flow rate of 0.2 L/min. The lower detection limits (3σ of the blank hydrazones) of HCHO and CH3CHO were 0.05 ppbv and 0.10 ppbv, respectively, in the case of 12-L air sample volume. Analytical response of a standard solution of DNPH-HCHO and DNPH-CH3CHO by the HPLC during a 10-day continuous measurement was unchanged and the relative standard deviation (RSD) was < 1.0%. Interferences from O3 and NO2 were insignificant in this annular diffusion scrubber method. Both for HCHO and CH3CHO measurements, concentrations from this developed system well agreed with those measured by a DNPH Silica cartridge method. 相似文献
58.
Yuichi Shimazaki Hiroshi Yokoyama Osamu Yamauchi 《Angewandte Chemie (International ed. in English)》1999,38(16):2401-2403
A unique bonding of indole to a metal ion has been established. Two new tridentate N ligands with a pendent indole ring gave CuI complexes 1 and 2 , the latter of which exhibits the new form of bonding between the CuI ion in a distorted tetrahedral geometry and the indole C(2)−C(3) moiety. The bond is dependent upon the length of the side chain and therefore the accessibility of the ring to the metal center. 相似文献
59.
60.
Keiichiro Fukumoto Masatoshi Chihiro Yuichi Shiratori Masataka Ihara Tetsuji Kametani Toshio Honda 《Tetrahedron letters》1982,23(29):2973-2976
Thermolysis of a benzocyclobutene derivative () prepared from norcamphor produced stereoselectively a tetracyclic compound (), which was converted to a lactone () having correct stereochemistry at C7, C8, C9, C11, C13, and C14 positions of (±)-klaineanone. 相似文献