全文获取类型
收费全文 | 2067篇 |
免费 | 42篇 |
国内免费 | 7篇 |
专业分类
化学 | 1380篇 |
晶体学 | 14篇 |
力学 | 24篇 |
综合类 | 1篇 |
数学 | 80篇 |
物理学 | 415篇 |
无线电 | 202篇 |
出版年
2021年 | 13篇 |
2020年 | 9篇 |
2019年 | 24篇 |
2018年 | 10篇 |
2017年 | 14篇 |
2016年 | 18篇 |
2015年 | 31篇 |
2014年 | 36篇 |
2013年 | 86篇 |
2012年 | 84篇 |
2011年 | 115篇 |
2010年 | 55篇 |
2009年 | 42篇 |
2008年 | 107篇 |
2007年 | 131篇 |
2006年 | 111篇 |
2005年 | 93篇 |
2004年 | 82篇 |
2003年 | 90篇 |
2002年 | 93篇 |
2001年 | 63篇 |
2000年 | 51篇 |
1999年 | 33篇 |
1998年 | 20篇 |
1997年 | 11篇 |
1996年 | 25篇 |
1995年 | 25篇 |
1994年 | 32篇 |
1993年 | 26篇 |
1992年 | 30篇 |
1991年 | 35篇 |
1990年 | 27篇 |
1989年 | 23篇 |
1988年 | 26篇 |
1987年 | 32篇 |
1986年 | 26篇 |
1985年 | 40篇 |
1984年 | 28篇 |
1983年 | 24篇 |
1982年 | 21篇 |
1981年 | 20篇 |
1980年 | 20篇 |
1979年 | 22篇 |
1978年 | 26篇 |
1977年 | 21篇 |
1976年 | 21篇 |
1975年 | 26篇 |
1974年 | 23篇 |
1973年 | 19篇 |
1972年 | 11篇 |
排序方式: 共有2116条查询结果,搜索用时 24 毫秒
1.
Yuki Shintani Taku Ohtomi Dr. Aya Shibata Dr. Yoshiaki Kitamura Koichiro M. Hirosawa Prof. Kenichi G. N. Suzuki Prof. Masato Ikeda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(8):e202104421
Aqueous self-assembly of short peptides has attracted growing attention for the construction of supramolecular materials for various bioapplications. Herein, we describe how the thermolysin-assisted biocatalytic construction of a dipeptide hydrazide from an N-protected amino acid and an amino acid hydrazide leads to the formation of thermally stable supramolecular hydrogels. In addition, we demonstrate the post-assembly modification of the supramolecular architectures constructed in situ tethering hydrazide groups as a chemical handle by means of fluorescence imaging. 相似文献
2.
Xin Sun Qiang Lu Moroz V. Takeuchi H. Gebara G. Wetzel J. Shuji Ikeda Changhwan Shin Tsu-Jae King Liu 《Electron Device Letters, IEEE》2008,29(5):491-493
A tri-gate bulk MOSFET design utilizing a low-aspect-ratio channel is proposed to provide an evolutionary pathway for CMOS scaling to the end of the roadmap. 3-D device simulations indicate that this design offers the advantages of a multi-gate FET (reduced variability in performance and improved scalability) together with the advantages of a conventional planar MOSFET (low substrate cost and capability for dynamic threshold-voltage control). 相似文献
3.
Shigeyuki Toki Igors Sics Benjamin S. Hsiao Syozo Murakami Masatoshi Tosaka Sirilux Poompradub Shinzo Kohjiya Yuko Ikeda 《Journal of Polymer Science.Polymer Physics》2004,42(6):956-964
The molecular orientation and strain‐induced crystallization of synthetic rubbers—polyisoprene rubber, polybutadiene rubber, and butyl rubber [poly(isobutylene isoprene)]—during uniaxial deformation were studied with in situ synchrotron wide‐angle X‐ray diffraction. The high intensity of the synchrotron X‐rays and the new data analysis method made it possible to estimate the mass fractions of the strain‐induced crystals and amorphous chain segments in both the oriented and unoriented states. Contrary to the conventional concept, the majority of the molecules (50–75%) remained in an unoriented amorphous state at high strains. Each synthetic rubber showed a different behavior of strain‐induced crystallization and molecular orientation during extension and retraction. Our results confirmed the occurence of strain‐induced networks in the synthetic rubbers due to the inhomogeneity of the crosslink distribution. The strain‐induced networks containing microfibrillar crystals and oriented amorphous tie chains were responsible for the ultimate mechanical properties. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 956–964, 2004 相似文献
4.
Yoshio Suzuki Noriyuki Tanji Chikako Ikeda Aki Honda Kenji Ookubo Daniel Citterio Suzuki Koji 《Analytical sciences》2004,20(3):475-482
Novel labeling reagents, called MS probes, which possess a positively charged quaternary amine moiety and can transform a neutral analyte into a charged compound by simply mixing with the analyte and allowing the mixture to stand from several minutes to 30 min at room temperature or while heating to 50 degrees C, were designed and synthesized for the highly sensitive detection of carbonyl, alcohol, carboxylic acid and primary amine samples by electrospray ionization mass spectrometry (ESI-MS). The positively charged products can be detected with high sensitivity in an ESI-MS system, which is the most popular liquid MS instrument. All of the labeled products showed a remarkably large increase in the molecular-ion peak abundance detection sensitivity of over 500-fold at picomolar concentration levels compared to that of unlabeled analytes in an ESI-MS system. These MS probes, used together with liquid MS detection, are widely applicable as a convenient method for the highly sensitive detection of less than picomolar levels of analytes, and therefore greatly enhance the power of ESI-MS analysis. 相似文献
5.
Mineo Hashizume Hiroaki Inoue Kiyofumi Katagiri Atsushi Ikeda Jun-Ichi Kikuchi 《Journal of Sol-Gel Science and Technology》2004,31(1-3):99-102
Morphological characterization of the organic-inorganic vesicular nanohybrids, Cerasomes, was performed in aqueous media from two aspects. Firstly, a novel Cerasome-forming lipid having two triethoxysilyl groups in the head moiety was synthesized and the physical property of the Cerasome was investigated. While the morphological stability of the Cerasomes, as evaluated from the vesicular collapse behavior against a micelle-forming nonionic surfactant, Triton-X 100, was extremely higher than that of the conventional phospholipid liposome, the stabilities were comparable to each other for the Cerasomes derived from the dual- and single-head lipids. On the other hand, the surface property of the Cerasome formed with the dual-head lipid more closely resembled the colloidal silica particles rather than that derived from the single-head lipid, as suggested by zeta-potential measurements. Secondly, the effect of the media pH on the morphological stability of the Cerasome formed with the single-head lipid was evaluated and appeared as a time difference in obtaining the morphological stability of the Cerasome. These morphological characteristics of the Cerasomes could be mainly owing to the development of the siloxane network on the vesicular surface. 相似文献
6.
7.
We synthesized a new intercalation compound, 1,5-diaminonaphathalene(DAN)-saponite where intercalated DAN molecules were shown to have a formal charge of +0.67 The measurement of optical diffuse reflectance spectra revealed the formation of electronic bands with a gap of ca. 1 eV suggesting semiconducting behaviour of this system. From ESR measurements, the radical formation in DAN-saponite was confirmed and the spin concentration was determined to be 1 spin per 200 and 300 DAN-molecules at 290 and 7.9 K, respectively. This temperature dependence of the spin density also implies the semiconductive nature of DAN-saponite. 相似文献
8.
In photochemical vapor deposition of aluminum film on silicon using dimethylaluminum hydride, (CH3)2AlH, a surface reaction dominated below a (CH3)2AlH pressure of 0.3 m Torr at 200°C, which was induced only with the 160 nm band emitted from a deuterium lamp. A gas-phase reaction occurred above 0.3 mTorr at 200°C, which could be induced by both 160 nm and 240 nm emission bands from the lamp. To distinguish between surface ad gas-phase reactions, a thickness profile was used. At 240°C the surface reaction could be induced even by the 240 nm band, while the deposits formed under illumination of the two bands were thinner than those obtained with only the 240 nm band, indicating occurrence of vacuum ultraviolet (VUV)-enhanced desorption. The mechanism responsible for the observed wavelength dependence in unclear. The electrical resistivity of the films deposited at 200°C was 4.5 μΩ cm, which did not change with wavelength. 相似文献
9.
For pt. I see ibid., vol., 31, no. 8, p. 1525-32 (1995). The plasma temperatures in microwave discharged CO2-N2-He laser gas mixtures were examined using the spectroscopic and electrostatic probe methods. A vibration temperature of N2 molecules, obtained spectroscopically, was determined to be nearly 7000 K without gas circulation and to be nearly 4000 K at the mass flow rate of 4.2 kg/h. It is found that an efficiency of laser output power exceed 14% (RF to laser output power conversion ratio) below the vibration temperature of 4000 K. The values of vibration temperature obtained were higher than those reported in DC discharges 相似文献
10.
Keishi Sakamoto Atsushi Kasugai Masaki Tsuneoka Koji Takahashi Yukiharu Ikeda Tsuyoshi Imai Takashi Nagashima Mitsuru Ohta Tsuyoshi Kariya Kenichi Hayashi Yoshika Mitsunaka Yosuke Hirata Yasuyuki Itoh Yukio Okazaki 《Journal of Infrared, Millimeter and Terahertz Waves》1997,18(9):1637-1654
A development of 170GHz/500kW level gyrotron was carried out as R&D work of ITER. The oscillation mode is TE31,8. In a short pulse experiment, the maximum power of 750kW was achieved at 85kV/40A. The efficiency was 22%. In the depressed collector operation, 500kW/36%/50ms was obtained. The maximum efficiency of 40% was obtained at PRF=470kW whereas the power decrease by the electron trapping was observed. Pulse extension was done up to 10s at PRF=170kW with the depressed collector operation. The power was limited by the temperature increase of the output window. 相似文献