全文获取类型
收费全文 | 10449篇 |
免费 | 1068篇 |
国内免费 | 573篇 |
专业分类
化学 | 7134篇 |
晶体学 | 146篇 |
力学 | 1640篇 |
综合类 | 27篇 |
数学 | 810篇 |
物理学 | 2333篇 |
出版年
2024年 | 17篇 |
2023年 | 71篇 |
2022年 | 182篇 |
2021年 | 192篇 |
2020年 | 397篇 |
2019年 | 261篇 |
2018年 | 238篇 |
2017年 | 300篇 |
2016年 | 448篇 |
2015年 | 401篇 |
2014年 | 456篇 |
2013年 | 697篇 |
2012年 | 654篇 |
2011年 | 565篇 |
2010年 | 525篇 |
2009年 | 671篇 |
2008年 | 705篇 |
2007年 | 751篇 |
2006年 | 644篇 |
2005年 | 524篇 |
2004年 | 517篇 |
2003年 | 430篇 |
2002年 | 367篇 |
2001年 | 264篇 |
2000年 | 242篇 |
1999年 | 260篇 |
1998年 | 240篇 |
1997年 | 165篇 |
1996年 | 125篇 |
1995年 | 150篇 |
1994年 | 101篇 |
1993年 | 84篇 |
1992年 | 91篇 |
1991年 | 67篇 |
1990年 | 51篇 |
1989年 | 40篇 |
1988年 | 30篇 |
1987年 | 25篇 |
1986年 | 17篇 |
1985年 | 20篇 |
1984年 | 28篇 |
1983年 | 5篇 |
1982年 | 17篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 14篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1975年 | 3篇 |
1970年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Ugur Gven 《Acta Mechanica Solida Sinica》2011,24(6):506-509
In this work a bi-material beam exhibiting partly bilinear behaviour under a uniform temperature change is analyzed. The essence of solution is based on the approach of Timoshenko’s mechanics of materials. The main aim of the present analysis is to understand the effect of the bilinear behaviour on the peeling moment. This theoretical mechanics model mentioned here can give us useful insights to improve the resistance against the delamination. 相似文献
992.
993.
994.
995.
Alois Kuhn María Martín Flaviano García-Alvarado 《Journal of solid state chemistry》2010,183(1):20-3508
The new ramsdellite series LiTi2−yVyO4 (0≤y≤1) has been prepared by conventional solid state chemistry techniques and was characterized by X-ray powder diffraction and electron diffraction. To our knowledge, this is the first report on ramsdellites containing vanadium. The magnetic behaviour of these ramsdellites is strongly influenced by its vanadium content. In this sense, LiTi2O4 (y=0) exhibits metallic-like temperature independent paramagnetism, but d electrons tend to localize with increasing V content. LiTiVO4, though also paramagnetic, follows then the Curie-Weiss law. The crossover from delocalized to localized electrons is observed between compositions y=0.6 and 0.8. For y≥0.8 the magnetic results evidence an isovalent substitution mechanism of trivalent Ti by V. The electrochemical lithium intercalation and deintercalation chemistry of LiTi2−yVyO4 is grouped into two different operating voltage regions. Reversible lithium deintercalation of vanadium-substituted ramsdellite titanates LiTi2−yVyO4 in the high voltage range 2-3 V vs. Li occurs in two main steps, one at about 2 V and the other at about 3 V. The 3 V process capacity increases with the vanadium content, while the 2 V capacity decreases at the same time. The vanadium to titanium substitution rate in LiTi2O4 was found to be beneficial to the specific energy in as much as a 50% increase (1 V) of the working voltage is observed. On the other hand, reversible lithium intercalation in vanadium-substituted ramsdellite titanates LiTi2−yVyO4 in the low voltage range 1-2 V vs. Li occurs in one main single step, in which the capacity is not affected by the vanadium content, although vanadium-doping produces an improved capacity retention with an excellent cycling behaviour observed for y≤0.6. 相似文献
996.
Fourier transform infrared (FTIR) spectroscopy has being emphasised as a widespread technique in the quick assess of food components. In this work, procyanidins were extracted with methanol and acetone/water from the seeds of white and red grape varieties. A fractionation by graded methanol/chloroform precipitations allowed to obtain 26 samples that were characterised using thiolysis as pre-treatment followed by HPLC-UV and MS detection. The average degree of polymerisation (DPn) of the procyanidins in the samples ranged from 2 to 11 flavan-3-ol residues. FTIR spectroscopy within the wavenumbers region of 1800-700 cm−1 allowed to build a partial least squares (PLS1) regression model with 8 latent variables (LVs) for the estimation of the DPn, giving a RMSECV of 11.7%, with a R2 of 0.91 and a RMSEP of 2.58. The application of orthogonal projection to latent structures (O-PLS1) clarifies the interpretation of the regression model vectors. Moreover, the O-PLS procedure has removed 88% of non-correlated variations with the DPn, allowing to relate the increase of the absorbance peaks at 1203 and 1099 cm−1 with the increase of the DPn due to the higher proportion of substitutions in the aromatic ring of the polymerised procyanidin molecules. 相似文献
997.
Saram Lee Segyeong Joo Sejin Park Soyoun Kim Hee Chan Kim Taek Dong Chung 《Electrophoresis》2010,31(10):1623-1629
In this study, in situ surface‐enhanced Raman scattering (SERS) decoding was demonstrated in microfluidic chips using novel thin micro gold shells modified with Raman tags. The micro gold shells were fabricated using electroless gold plating on PMMA beads with diameter of 15 μm. These shells were sophisticatedly optimized to produce the maximum SERS intensity, which minimized the exposure time for quick and safe decoding. The shell surfaces produced well‐defined SERS spectra even at an extremely short exposure time, 1 ms, for a single micro gold shell combined with Raman tags such as 2‐naphthalenethiol and benzenethiol. The consecutive SERS spectra from a variety of combinations of Raman tags were successfully acquired from the micro gold shells moving in 25 μm deep and 75 μm wide channels on a glass microfluidic chip. The proposed functionalized micro gold shells exhibited the potential of an on‐chip microfluidic SERS decoding strategy for micro suspension array. 相似文献
998.
Wolfgang Scherer Prof. Dr. Christoph Hauf Dipl.‐Phys. Manuel Presnitz Dipl.‐Phys. Ernst‐Wilhelm Scheidt Dr. Georg Eickerling Dr. Volker Eyert Dr. Rolf‐Dieter Hoffmann Dr. Ute C. Rodewald Dipl.‐Ing. Adrienne Hammerschmidt Dr. Christian Vogt Dr. Rainer Pöttgen Prof. Dr. 《Angewandte Chemie (International ed. in English)》2010,49(9):1578-1582
999.
1000.
Leonardo C. Ferreira Carlos A. L. Filgueiras Lorenzo C. Visentin Jairo Bordinho Manfredo Hrner 《无机化学与普通化学杂志》2008,634(11):1896-1900
The preparation and characterization of two novel HgCl2 and Hg(SCN)2 complexes with bis[N‐(2‐tert‐butylphenyl)imine]acenaphthene is here described. One‐pot reaction techniques were used, leading to high yields of 75 % and 81 %, respectively. The complexes were characterized by microanalysis, i.r. and 1HNMR spectroscopy, and by single crystal X‐ray diffraction. The structures of the complexes present similar characteristics, the most outstanding being the formation of dimers via intermolecular interaction. Whereas the HgCl2 complex shows a unidimensional network due to strong π–π interactions, its Hg(SCN)2 counterpart displays a supramolecular arrangement resulting from non classical hydrogen bond formation. 相似文献