全文获取类型
收费全文 | 3129篇 |
免费 | 60篇 |
国内免费 | 12篇 |
专业分类
化学 | 2348篇 |
晶体学 | 40篇 |
力学 | 36篇 |
数学 | 176篇 |
物理学 | 601篇 |
出版年
2022年 | 18篇 |
2021年 | 32篇 |
2020年 | 18篇 |
2019年 | 42篇 |
2018年 | 19篇 |
2017年 | 18篇 |
2016年 | 37篇 |
2015年 | 31篇 |
2014年 | 49篇 |
2013年 | 149篇 |
2012年 | 108篇 |
2011年 | 136篇 |
2010年 | 83篇 |
2009年 | 73篇 |
2008年 | 145篇 |
2007年 | 157篇 |
2006年 | 156篇 |
2005年 | 160篇 |
2004年 | 130篇 |
2003年 | 124篇 |
2002年 | 133篇 |
2001年 | 46篇 |
2000年 | 66篇 |
1999年 | 56篇 |
1998年 | 49篇 |
1997年 | 41篇 |
1996年 | 44篇 |
1995年 | 35篇 |
1994年 | 37篇 |
1993年 | 41篇 |
1992年 | 57篇 |
1991年 | 33篇 |
1990年 | 31篇 |
1989年 | 35篇 |
1988年 | 44篇 |
1987年 | 47篇 |
1986年 | 36篇 |
1985年 | 64篇 |
1984年 | 62篇 |
1983年 | 38篇 |
1982年 | 43篇 |
1981年 | 47篇 |
1980年 | 37篇 |
1979年 | 56篇 |
1978年 | 52篇 |
1977年 | 39篇 |
1976年 | 47篇 |
1975年 | 38篇 |
1974年 | 38篇 |
1973年 | 44篇 |
排序方式: 共有3201条查询结果,搜索用时 15 毫秒
951.
952.
Summary A general analysis of the characteristics of a resonant transducer for gravitational-wave antennas whose resonator has a general
mode of vibration has been made using a Lagrangian formalism. The method has been applied to investigate the characteristics
of the resonant capacitive transducer developed at the University of Rome and mounted on the cryogenic gravitational-wave
antenna built at CERN, finding results in good agreement with the experimental behaviour.
Riassunto Si usa il formalismo lagrangiano per svolgere un'analisi delle caratteristiche di un trasduttore risonante per antenne gravitazionali nel caso generale in cui il risuonatore utilizzato abbia un modo di vibrazione di forma qualunque. Il metodo è applicato allo studio delle caratteristiche del trasduttore risonante capacitivo sviluppato alla I Università di Roma e montato sull'antenna gravitazionale criogenica realizzata al CERN, trovando risultati in buon accordo con i valori sperimentali.
Резюме Используя Лагранжев формализм, проводится обший анализ характеристик резонансного датчика для антенн гравитационных волх. Предложенный метод применяется для исследования характеристик резонансного емкостного датчика, разработанного в Римском Университете и смонтированного на криогенной антенне гравитационных волн в ЦЕРНе. Полученные результаты хорошо согласуются с экспериментальными данными.相似文献
953.
ESR measurements were performed for the coenzyme Q1, chromanoxyl and chromenoxyl radicals obtained by oxidizing the phenol precursors with PbO2 in toluene, and the proton hyperfine splittings were correctly determined. 相似文献
954.
Yoshimori Omote Kazuo Harada Atsushi Tomotake Choji Kashima 《Journal of heterocyclic chemistry》1984,21(6):1841-1844
The reaction of 2,3-dihydro-1H-cyclopent[b]indole 3 and 1,2,3,4-tetrahydrocarbazole 4 with substituted o-benzoquinones yielded [4.3.3]- and [4.4.3]propellanes, respectively. The physical and chemical properties of the propellane compounds were investigated and a mechanism for the formation of the propellane compounds was discussed. 相似文献
955.
Daisuke Nagai Kensuke Yokota Takuma Ogawa Bungo Ochiai Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2008,46(2):733-739
Cationic ring‐opening copolymerization behavior of trioxane (TOX) and a seven‐membered cyclic carbonate, 1,3‐dioxepan‐2‐one (7CC) is described. When TOX and 7CC were cationically copolymerized under various feed ratios using trifluoromethane sulfonic acid (TfOH) as an initiator in nitrobenzene at 30 °C, 7CC was consumed faster than TOX and the decarboxylation was accompanied to afford the corresponding polyacetal–polycarbonate type copolymers containing poly(oxytetramethylene) units. The copolymer composition could be controlled by the feed ratio of 7CC, whose increase resulted in the high copolymer composition of the 7CC unit. The solubility of the copolymers increased as the increase of the 7CC content. Thermogravimetric, size‐exclusion chromatographic, and X‐ray analyses of the copolymers suggest that the sequences of the copolymer chains consist of the segments containing the units originated from 7CC and those with TOX unit‐rich compositions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 733–739, 2008 相似文献
956.
To evaluate the influence of a printed wiring board (PWB) with a high coefficients of thermal expansion (CTE) on the thermal deformation of a small outline J-leaded electronic package (SOJ), a newly developed phase-shifting method was applied to moiré interferometry. This phase-shifting moiré interferometry method uses a wedged glass plate as a phase shifter to obtain displacement fields with a sensitivity of 100 nm/line. This technique also enabled the quantitative determination of strain distributions in all observation areas. Thermal loading was applied from room temperature (25 °C) to an elevated temperature (100 °C), and then the thermal strains of SOJ with and without the PWB were compared. The results showed that the concentrations of the longitudinal strains εxx and εyy became increasingly prominent when mounted on the PWB, and the shear strains γxy were concentrated at the corners of the silicon chip. The values of these strains increased by about 50% when the SOJ was mounted on the PWB. 相似文献
957.
A novel system for multiplexed optical fiber interferometric sensors is proposed applying the synthesis of optical coherence function with phase generated carriers. The ideal parameters of the laser diode frequency modulation for the phase generated carrier with the synthesis of the optical coherence function are discussed. A basic experimental setup including two interferometric sensors is constructed. The results show that the phase signal from the two sensors can successfully be demultiplexed by scanning the synthesized coherence peak. 相似文献
958.
959.
Kazuo Sasazawa Yuko Yamada Akiko Fujisawa Toshikazu Saitoh Katsuya Ueno Kazuya Oharu Hideo Sawada 《Colloid and polymer science》2005,283(7):812-816
Self-assembled fluorinated molecular aggregates formed by fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomers, N,N-dimethylacrylamide oligomers, and acrylic acid oligomers in methanol could selectively recognize fluoresceins as guest molecules to form a new class of fluorinated aggregates-fluorescein nanocomposites. These fluorinated fluorescein nanocomposites that are obtained exhibit an extraordinarily enhanced light absorption (max ca. 440 nm) compared to that (maxs 452, 480 nm) of the parent fluorescein in the absence of fluorinated aggregates. 相似文献
960.
Kitagawa Y Sentoku Y Akamatsu S Sakamoto W Kodama R Tanaka KA Azumi K Norimatsu T Matsuoka T Fujita H Yoshida H 《Physical review letters》2004,92(20):205002
An ultraintense laser injected a 10 J of power at 1.053 microm in 0.5 ps into a glass capillary of 1 cm long and 60 microm in diameter and accelerated plasma electrons to 100 MeV. One- and two-dimensional particle codes describe wakefields with 10 GV/m gradient excited behind the laser pulse, which are guided by a plasma density channel far beyond the Rayleigh range. The blueshift of the laser spectrum supports that a plasma of 10(16) cm(-3) is inside the capillary. A bump at the high energy tail suggests the electron trapping in the wakefield. 相似文献