全文获取类型
收费全文 | 1219篇 |
免费 | 19篇 |
国内免费 | 3篇 |
专业分类
化学 | 919篇 |
晶体学 | 4篇 |
力学 | 21篇 |
数学 | 56篇 |
物理学 | 241篇 |
出版年
2021年 | 8篇 |
2020年 | 8篇 |
2019年 | 13篇 |
2018年 | 7篇 |
2017年 | 6篇 |
2016年 | 18篇 |
2015年 | 15篇 |
2014年 | 19篇 |
2013年 | 68篇 |
2012年 | 52篇 |
2011年 | 53篇 |
2010年 | 26篇 |
2009年 | 26篇 |
2008年 | 61篇 |
2007年 | 50篇 |
2006年 | 59篇 |
2005年 | 55篇 |
2004年 | 45篇 |
2003年 | 54篇 |
2002年 | 43篇 |
2001年 | 42篇 |
2000年 | 27篇 |
1999年 | 18篇 |
1997年 | 13篇 |
1996年 | 7篇 |
1995年 | 10篇 |
1994年 | 19篇 |
1993年 | 7篇 |
1992年 | 25篇 |
1991年 | 19篇 |
1990年 | 26篇 |
1989年 | 18篇 |
1988年 | 19篇 |
1987年 | 18篇 |
1986年 | 24篇 |
1985年 | 37篇 |
1984年 | 19篇 |
1983年 | 13篇 |
1982年 | 13篇 |
1981年 | 19篇 |
1980年 | 18篇 |
1979年 | 18篇 |
1978年 | 12篇 |
1977年 | 18篇 |
1976年 | 10篇 |
1975年 | 15篇 |
1974年 | 11篇 |
1973年 | 13篇 |
1969年 | 8篇 |
1968年 | 6篇 |
排序方式: 共有1241条查询结果,搜索用时 0 毫秒
81.
R. A. Ganeev M. Baba M. Morita A. I. Ryasnyanskii M. Suzuki M. Turu H. Kuroda 《Optics and Spectroscopy》2004,97(5):735-745
The saturated nonlinear absorption and Kerr nonlinearities of an aqueous pseudoisocyanine solution are investigated at the wavelengths of 532 and 529 nm with the use of pulsed laser radiation of different duration (8 ns and 475 fs). The measured values of the nonlinear refractive indices amount to ?6×10?12 (t=8 ns) and ?8×10?14 cm2W?1 (t=475 fs). The change in self-action effects in pseudoisocyanine from self-defocusing to self-focusing revealed in the case of increasing intensity of femtosecond laser pulses is attributed to the effect of a fifth-order nonlinear optical process. The nonlinear refractive index responsible for this process amounts to 4×10?24 cm4 W?2. The imaginary part of the third-order nonlinear susceptibility, responsible for the induced transparency of the pseudoisocyanine solution, is Imχ (3)=?2×10?12 esu. Temporal changes in the shape of nanosecond laser pulses due to the nonlinear refraction induced by a thermal process are analyzed. 相似文献
82.
Shirakawa E Morita R Tsuchimoto T Kawakami Y 《Journal of the American Chemical Society》2004,126(42):13614-13615
Molecular hydrogen adds to aliphatic and aromatic alkynylstannanes in the presence of a ruthenium catalyst, pushing the stannyl group to the adjacent carbon atom to give alpha-substituted vinylstannanes. This is the first achievement of hydrogenation of alkynylstannanes, which is applicable also to the deuteration affording precursors for an important class of deuterium-labeled compounds. 相似文献
83.
Morita Y Nishida S Kobayashi T Fukui K Sato K Shiomi D Takui T Nakasuji K 《Organic letters》2004,6(9):1397-1400
[structure: see text] A bowl-shaped neutral radical with a corannulene system has been designed and synthesized for the first time as a stable solid in air. An unequivocal characterization of the electronic properties of the radical shows that an appreciable amount of spin delocalization extends onto the corannulene unit's curved surface. 相似文献
84.
Zegers RG Sumihama M Ahn DS Ahn JK Akimune H Asano Y Chang WC Daté S Ejiri H Fujimura H Fujiwara M Hicks K Hotta T Imai K Ishikawa T Iwata T Kawai H Kim ZY Kino K Kohri H Kumagai N Makino S Matsumura T Matsuoka N Mibe T Miwa K Miyabe M Miyachi Y Morita M Muramatsu N Nakano T Niiyama M Nomachi M Ohashi Y Ooba T Ohkuma H Oshuev DS Rangacharyulu C Sakaguchi A Sasaki T Shagin PM Shiino Y Shimizu H Sugaya Y Toyokawa H Wakai A Wang CW Wang SC Yonehara K Yorita T Yoshimura M Yosoi M 《Physical review letters》2003,91(9):092001
Beam polarization asymmetries for the p(gamma-->,K+)Lambda and p(gamma-->,K+)Sigma(0) reactions are measured for the first time for E(gamma)=1.5-2.4 GeV and 0.6相似文献
85.
We present measurements of ac complex resistivity, as well as dc resistivity, for a thick amorphous MoxSi1-x film at low temperatures ( T>0.04 K) in various constant fields B. We find that the vortex glass transition (VGT) persists down to T approximately 0.04Tc0 up to B approximately 0.9Bc2(0), where Tc0 and Bc2(0) are the mean-field transition temperature and upper critical field at T = 0, respectively. In the limit T-->0, the VGT line Bg(T) extrapolates to a field below Bc2(0), while the dc resistivity rho(T) tends to the finite nonzero value in fields just above Bg(0). These results indicate the presence of a metallic quantum vortex liquid at T = 0 in the regime Bg(0)相似文献
86.
Narihara K Watanabe KY Yamada I Morisaki T Tanaka K Sakakibara S Ida K Sakamoto R Ohyabu N Ashikawa N Emoto M Funaba H Goto M Hayashi H Idei H Ikeda K Inagaki S Inoue N Kaneko O Kawahata K Kobuchi T Komori A Kubo S Kumazawa R Masuzaki S Miyazawa J Morita S Motojima O Murakami S Muto S Mutoh T Nagayama Y Nakamura Y Nakanishi H Nishimura K Noda N Notake T Ohdachi S Oka Y Ohkubo K Osakabe M Ozaki S Peterson BJ Sagara A Saito K Sasao H Sasao M Sato K Sato M Seki T Shimozuma T Shoji C Sudo S 《Physical review letters》2001,87(13):135002
It was observed that the vacuum magnetic island produced by an external error magnetic field in the large helical device shrank in the presence of plasma. This was evidenced by the disappearance of flat regions in the electron temperature profile obtained by Thomson scattering. This island behavior depended on the magnetic configuration in which the plasmas were produced. 相似文献
87.
Ultrasonic motors are suitable for a micro-actuator because of a direct drive, no brake and their simple construction. In order to fabricate micro-ultrasonic motors, a piezoelectric thin film is essential. In this study, a hydrothermal method was adopted to deposit a PZT thin film. The dimensions of the stator transducer were: outer diameter, 1.4 mm; inner diameter, 1.2 mm; and length, 5.0 mm. The resonance frequency of the stator transducer was 227 kHz, and the vibration amplitude was 58 nmp-p at an input voltage of 4.0 Vp-p. The maximum revolution speed was 680 rpm, and the maximum starting torque was 0.67 microNm. The experimental conditions were 20 Vp-p and 5.3 mN pre-load. The motor property versus scale was investigated using an equivalent circuit. The calculated results indicated that the output torque of the 100 microns diameter motor was 27 nNm. 相似文献
88.
Applications of an automated apparatus for two-dimensional electrophoresis, Model TEP-1, for microsequence analyses of proteins. 总被引:1,自引:0,他引:1
Two-dimensional electrophoresis has become a rapid and powerful separation method for the preparation of samples for sequence analysis depending on the development of automated microsequencers accompanied by a blotting technique. We have constructed an automated apparatus for two-dimensional electrophoresis, Model TEP-1, which allows precise analytical runs under computer-control with a fully automated transfer from the first- to the second-dimensional gel. In the present paper we describe several applications of TEP-1 followed by blotting and sequencing to reveal the primary structure of proteins in a complex mixture. Several known and unknown proteins were analyzed. Enzymatic digests of proteins could be directly applied onto the TEP-1, in which a gel of lower molecular weight proteins was used as the second dimension. Subsequent blotting and sequencing provided internal sequence information. The use of TEP-1, followed by blotting, provides spots containing ca. 10-100 pmol protein. These figures permitted the identification of 10-40 amino acid residues from the N-terminus. The TEP-1 provides a simple and rapid separation of complex mixtures obtained from natural sources and chemical, biological or genetic products. 相似文献
89.
An emulsion polymerization of styrene in the presence of an amphoteric surfactant; N,N-dimethyl-n-laurylbetaine (LNB) was carried out at pH 7.0. The polymerization rate and the concentration of the latex particle were proportional to the LNB concentration of 0.6 power. The latex particle sizes became smaller with increasing concentrations of LNB. The molecular weights of polystyrene latices increased with the concentration of LNB. The zeta-potentials of latex particles were significantly dependent on the pH, and showed the existence of an isoelectric point. 相似文献
90.