全文获取类型
收费全文 | 318篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
化学 | 173篇 |
晶体学 | 11篇 |
力学 | 6篇 |
数学 | 15篇 |
物理学 | 120篇 |
出版年
2023年 | 2篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 5篇 |
2015年 | 6篇 |
2014年 | 15篇 |
2013年 | 10篇 |
2012年 | 17篇 |
2011年 | 16篇 |
2010年 | 14篇 |
2009年 | 12篇 |
2008年 | 19篇 |
2007年 | 10篇 |
2006年 | 13篇 |
2005年 | 11篇 |
2004年 | 16篇 |
2003年 | 14篇 |
2002年 | 20篇 |
2001年 | 12篇 |
2000年 | 4篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1942年 | 2篇 |
排序方式: 共有325条查询结果,搜索用时 15 毫秒
1.
Albrecht H Binder U Harder G Lembke-Koppitz I Philipp A Schmidt-Parzefall W Schröder H Schulz HD Wurth R Donker JP Drescher A Matthiesen U Scheck H Spaan B Spengler J Wegener aD Gabriel JC Schubert KR Stiewe J Waldi R Weseler S Brown NN Edwards KW Frisken WR Fukunaga C Gilkinson DJ Gingrich DM Goddard M Kapitza H Kim PC Kutschke R MacFarlane DB McKenna JA McLean KW Nilsson AW Orr RS Padley P Patel PM Prentice JD Seywerd HC Stacey BJ Yoon T Yun JC Ammar R Coppage D Davis R Kanekal S Kwak N 《Physical review letters》1986,56(6):549-552
2.
Phenotyping of erythrocyte acid phosphatase (EAP) and esterase D (ESD) by cellulose acetate membrane isoelectric focusing (CAM-IEF) under a nonequilibrium condition is described. In an attempt to improve the method of CAM-IEF, we shortened the electrode distance to provide a higher field strength at a given (low) voltage. Various carrier ampholytes for EAP typing and various chemical separators for ESD typing were also tested. Good separations were obtained after 30 min IEF for EAP typing and 25 min for ESD typing. When applied to blood stains and stored for various periods at room temperature, the stains up to 8 months old could still be phenotyped for EAP and those up to 4 weeks old for ESD. CAM-IEF is suitable for routine forensic work of EAP and ESD phenotyping. 相似文献
3.
Anucha Wannagon Rikuo Ota Takashi Wakasugi Jiro Fukunaga 《Journal of Sol-Gel Science and Technology》2000,19(1-3):795-798
SiO2-TiO2-ZrO2 and 5Na2O·95(SiO2 + TiO2 + ZrO2) gels were synthesized and role of Na2O in gel formation and crystallization behavior of gels were studied. From Si(OC2H5)4, Ti(iso-OC3H7)4, Zr(n-OC3H7)4 and NaOCH3 solutions in EtOH without H2O, transparent and opaque gels were obtained. Opaque bulk gels, rich in TiO2 or ZrO2 composition in Na2O containing SiO2-TiO2-ZrO2 system, contain agglomerated spherical particles of diameter small <10 m, in contrast with opaque gels having large particles <30 m in alkali-free SiO2-TiO2-ZrO2 system. Crystallization temperature (Tc) was measured by DTA on dried gels. Compared with the alkali-free SiO2-TiO2-ZrO2 gels, 5 mol% Na2O containing gels gave lower Tc in SiO2 rich compositions and higher in TiO2 rich or ZrO2 rich compositions. 相似文献
4.
N Otsuka M Fukunaga K Morita S Ono K Nagai T Furukawa S Yanagimoto T Tomomitsu H Kawahara H Tanaka 《Radioisotopes》1988,37(6):330-335
In order to detect the varicocele, scrotal scintigraphies by using 99mTc-HSA-D were performed in 14 patients with male infertile or palpable mass in left scrotum on physical examinations. Abnormal pooling of 99mTc-HSA-D, indicative of varicocele lesion, could be found in left scrotum in 9 cases, confirmed surgically or clinically. Compared with 99mTc-HSA, 99mTc-HSA-D was superior in high uptake ratio of varicocele to soft tissue and in nonvisualization of bladder. Thus, 99mTc-HSA-D scrotal scintigraphy seemed to be of a great use to detect the varicocele. 相似文献
5.
Phototriggered self-assembly of hydrogen-bonded rosette 总被引:2,自引:0,他引:2
Yagai S Nakajima T Karatsu T Saitow K Kitamura A 《Journal of the American Chemical Society》2004,126(37):11500-11508
Azobenzene-appended melamine M2 and barbiturate B2, both possessing bulky tridodecyloxyphenyl (TDP) wedge(s), were designed and synthesized to establish a photoresponsive hydrogen-bonded supramolecular assembly. The geometrical isomer EE-M2 bearing two E-azobenzene moieties easily complexed with B2, affording a remarkably stable cyclic hexamer EE-M2(3).B2(3) (rosette) in chloroform, toluene, and methylcyclohexane, as confirmed by size exclusion chromatography, dynamic light scattering, (1)H NMR, and UV-vis studies. The E --> Z photoisomerization of the azobenzene moieties upon irradiation with UV light was significantly suppressed in the rosette because of the steric crowding of the TDP wedges (total of nine TDP wedges in a rosette), whereas irradiation of the monomeric EE-M2 resulted in facile transformation into ZZ-M2 bearing two Z-azobenzene moieties. (1)H NMR studies of the complexation of the initially photogenerated ZZ-M2 with B2 revealed that it is hard for ZZ-M2 to form a rosette with B2 because of the intermolecular steric interaction between the TDP wedges. The photoregulatable complexation efficiency of M2 allowed us to accomplish the phototriggered formation of the rosette by irradiation of a monomeric mixture of ZZ-M2 and B2 using visible light. 相似文献
6.
Toshiharu Arai 《Tetrahedron letters》2004,45(30):5921-5924
A stereoselective total synthesis of (+)-cylindricine C has been achieved starting with (S)-N-Boc-2-pyrrolidinone. The key elements of this synthesis involve the sequence of reactions including BF3-mediated addition of the allyl Grignard reagent to the cyclic imine, spirocyclization via enamine formation, and intramolecular Michael addition to form the tricyclic core. 相似文献
7.
T Furukawa Y Fujibayashi M Fukunaga A Yokoyama 《Chemical & pharmaceutical bulletin》1990,38(8):2285-2286
To obtain radiogallium labeled immunoglobulin G with a high specific radioactivity for in vitro use, a 67Ga source was purified by extraction from 67Ga-gallium citrate with butyl acetate, and a 67Ga-labeling solution was produced. This solution was then used to label a deferoxamine-immunoglobulin G conjugate. Both a very high specific radioactivity (872 +/- 56 MBq/mg) and a high labeling efficiency (94.0%) were achieved. 相似文献
8.
Toshiharu Okui Yuriko Saito Tatsuya Okubo Masayoshi Sadakata 《Journal of Sol-Gel Science and Technology》1995,5(2):127-134
Selective gas permeation of porous organic/inorganic hybrid membranes via sol-gel route and its thermal stability are described. Separation performance of the hybrid membrane was improved compared with porous membranes governed by the Knudsen flow, and gas permeability was still much higher than that through nonporous membranes. Additionally, it was shown that these membranes were applicable at higher temperatures than organic membranes.SEM observation demonstrated that the thin membrane was crack-free. Nitrogen physisorption isotherms showed the pore size was in the range of nanometers. Gas permeability through this membrane including phenyl group was in the range of 10–8 [cc(STP) cm/(cm2 s cmHg)] at 25°C. The ratios of O2/N2 and CO2/N2 were 1.5 and 6.0, respectively, showing the permeation was not governed by the Knudsen flow. The permeability decreased as the temperature increased. Furthermore, the specific affinity between gas molecules and surface was observed not only in the permeation data of the hybrid membranes but in the physisorption data. These results suggested that the gas permeation through the hybrid membrane was governed by the surface flow mechanism.Thermal analysis indicated that these functional groups were still stable at higher temperatures. The phenyl group especially remained undamaged even at 400°C. 相似文献
9.
Hiroyoshi Nakajima Katsuhiro Yamada Yuki Iseki Satoru Hosoda Ayako Hanai Yasunori Oumi Toshiharu Teranishi Tsuneji Sano 《Journal of polymer science. Part A, Polymer chemistry》2003,41(24):3324-3332
Polypropylene (PP)/Ti-MCM-41 nanocomposites were prepared by isospecific propylene polymerization with Ti-MCM-41/Al(i-C4H9)3 catalyst. The cross polarization/magic angle spinning (CP/MAS) 13C NMR spectrum of the composite was similar to that of the conventional isotactic PP, and the decrease in the pore volume of Ti-MCM-41 in the nanocomposites, as measured by N2 adsorption, was consistent with the value calculated from the weight loss in the thermogravimetric analysis (TGA) curve; both these facts attest to propylene polymerization within the mesopores of Ti-MCM-41. Alkali treatment followed by extraction with o-dichlorobenzene allows us to extract the confined PP out of the Ti-MCM-41 mesopores. Although the PP/Ti-MCM-41 nanocomposites do not exhibit a crystalline melting point, the same PP when extracted from the mesopores showed a clear melting point at 154.7 °C; this indicates that the crystallization of PP confined in mesopores is strongly hindered. For the PP polymerized within the confinement, the molecular weight (Mw) and molecular weight distribution (Mw/Mn) were 84,000 and 4.3, respectively; these values were considerably smaller than those of the PP polymerized concurrently outside the Ti-MCM-41 mesopores (Mw = 200,000–450,000, Mw/Mn = 40–75). Therefore, the confinement also has a marked effect on the molecular weight of the PP. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3324–3332, 2003 相似文献