全文获取类型
收费全文 | 2487篇 |
免费 | 73篇 |
国内免费 | 6篇 |
专业分类
化学 | 1658篇 |
晶体学 | 21篇 |
力学 | 61篇 |
数学 | 260篇 |
物理学 | 566篇 |
出版年
2024年 | 3篇 |
2023年 | 18篇 |
2022年 | 63篇 |
2021年 | 92篇 |
2020年 | 68篇 |
2019年 | 72篇 |
2018年 | 82篇 |
2017年 | 59篇 |
2016年 | 119篇 |
2015年 | 84篇 |
2014年 | 112篇 |
2013年 | 156篇 |
2012年 | 158篇 |
2011年 | 207篇 |
2010年 | 121篇 |
2009年 | 115篇 |
2008年 | 142篇 |
2007年 | 147篇 |
2006年 | 112篇 |
2005年 | 96篇 |
2004年 | 80篇 |
2003年 | 42篇 |
2002年 | 57篇 |
2001年 | 20篇 |
2000年 | 36篇 |
1999年 | 15篇 |
1998年 | 26篇 |
1997年 | 15篇 |
1996年 | 22篇 |
1995年 | 26篇 |
1994年 | 21篇 |
1993年 | 13篇 |
1992年 | 11篇 |
1991年 | 21篇 |
1990年 | 17篇 |
1989年 | 10篇 |
1988年 | 11篇 |
1987年 | 11篇 |
1986年 | 10篇 |
1985年 | 11篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1975年 | 4篇 |
1971年 | 2篇 |
排序方式: 共有2566条查询结果,搜索用时 15 毫秒
51.
Discontinuous changes of the lattice parameters at the Mott metal-insulator transition are detected by high-resolution dilatometry on deuterated crystals of the layered organic conductor kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Br. The uniaxial expansivities uncover a striking and unexpected anisotropy, notably a zero effect along the in-plane c axis along which the electronic interactions are relatively strong. A huge thermal expansion anomaly is observed near the end point of the first-order transition line enabling us to explore the critical behavior with very high sensitivity. The analysis yields critical fluctuations with an exponent alpha approximately 0.8+/-0.15 at odds with the novel criticality recently proposed for these materials [Kagawa et al., Nature (London) 436, 534 (2005)]. Our data suggest an intricate role of the lattice degrees of freedom in the Mott transition for the present materials. 相似文献
52.
53.
54.
Anjos JC Appel JA Bean A Bracker SB Browder TE Cremaldi LM Duboscq JE Elliot JR Escobar CO Gibney MC Hartner GF Karchin PE Kumar BR Losty MJ Luste GJ Mantsch PM Martin JF McHugh S Menary SR Morrison RJ Nash T Ong P Pinfold J Punkar G Purohit MV Santoro AF Shoup AL Sliwa K Sokoloff MD Souza MH Spalding WJ Streetman ME Stundzia AB Witherell MS 《Physical review D: Particles and fields》1991,43(3):R635-R640
55.
E. Baggio-Saitovitch R. B. Scorzelli I. Souza Azevedo C. Diaz-Aguila 《Hyperfine Interactions》1994,83(1):425-429
La2–x
Ca
x
Cu0.99Fe0.01O4–y
samples with 0.00 x 0.30 were studied by X-ray diffraction and Mössbauer spectroscopy after heat treatment under different atmospheres (air, oxygen and helium). The variation of the relative population and the hyperfine interactions of the sites as well as the change in the lattice parameters were obtained.On leave from National Center for Scientific Research, PO Box 6990, Havana, Cuba. 相似文献
56.
José Carlos de Souza Kiihl 《Rendiconti del Circolo Matematico di Palermo》1980,29(3):411-419
In this paper we develop a technique to study the homomorphisma: MU * (B U1)→M U*?2 (B U1) defined by assigning to the class off: M→B U 1 the class off oi: N→B U1, wherei: N→M is the submanifold dual tof*(γ1)?f*(γ1), and γ1→B U is the 3 universal line boundle. So that we can present a (σn), where σnis the class of the classifying map of the canonical line boundle overC P n, in terms of the σi’s and chosen generators of Π★(M U). 相似文献
57.
58.
N. K. Leite J. G. Santos R. F. Souza G. M. Cabianchi F. O. Xavier B. M. Gomes L. B. Silveira A. C. Oliveira A. F.R. Rodriguez P. C. Morais 《The European physical journal. Special topics》2008,153(1):45-48
In this study we demonstrate the usefulness of the
Photoacoustic Spectroscopy (PAS) in the investigation of water collected
from a natural site located within the Amazon region, Brazil, during the wet
to dry seasons transition (May/2006). The water samples were collected from
different stages along a hydrologic pathway including precipitation water
(Prec), groundwater (GW), through flow water (TF), overland flow water (OF),
and stream flow water (SW). The observed photoacoustic spectral features, in
the 0.3 to 1.0 μm wavelength region, fall within three distinct bands
(C, S, and L). We found band-C, band-S and band-L occurring in the spectral
range of 0.30 to 0.40 μm, 0.40 to 0.45 μm and 0.45 to 1.0 μm
regions, respectively. The photoacoustic features shift peak positions and
change intensities for all samples investigated, thus supporting the
proposal of PAS as a useful technique to investigate water samples from
natural environments. 相似文献
59.
60.
Lisiani Ritter Eduarda Possa Larissa Bergoza Fabiana Agostini Sidnei M. Silva Leandro Tasso 《Biomedical chromatography : BMC》2020,34(11):e4977
Clindamycin is used for infections caused by Gram-positive and Gram-negative anaerobic pathogens and Gram-positive aerobes. Propionibacterium acnes is an important opportunistic microorganism of the human skin and is related to prostatitis. An LC–electrospray ionization–quadrupole time-of-flight–MS method was validated for determining clindamycin concentrations in plasma and prostate microdialysate. Clindamycin separation was carried out on a C18 column at 0.5 mL/min. The mobile phase employed gradient elution of formic acid and methanol. A mass spectrometer was operated in positive electrospray ionization mode to monitor ion 425.1784 and 253.1152 for clindamycin and cimetidine (internal standard), respectively. Linearity was obtained at 0.5–10.0 μg/mL (plasma) and 0.05–1.0 μg/mL (microdialysate) with coefficients of determination ≥0.999. The intra- and inter-day precision (coefficient of variation - CV%) values were ≤13.83% and 12.51% for plasma, respectively, and ≤10.90% and 9.35% for microdialysate, respectively. The accuracy was between 90.82% and 108.25% for plasma, and 96.97% and 106.98% for microdialysate. The present method was fully validated and applied to investigate clindamycin concentrations in both plasma and prostate by microdialysis in Wistar rats (80 mg/kg, intravenous). Because the penetration of antibiotics into the prostate may be restricted, this method allows us to investigate the prostate concentrations of clindamycin for the first time. 相似文献