全文获取类型
收费全文 | 12859篇 |
免费 | 336篇 |
国内免费 | 84篇 |
专业分类
化学 | 8934篇 |
晶体学 | 128篇 |
力学 | 275篇 |
数学 | 1802篇 |
物理学 | 2140篇 |
出版年
2023年 | 64篇 |
2022年 | 52篇 |
2021年 | 124篇 |
2020年 | 168篇 |
2019年 | 155篇 |
2018年 | 126篇 |
2017年 | 118篇 |
2016年 | 246篇 |
2015年 | 242篇 |
2014年 | 299篇 |
2013年 | 571篇 |
2012年 | 720篇 |
2011年 | 924篇 |
2010年 | 453篇 |
2009年 | 389篇 |
2008年 | 822篇 |
2007年 | 836篇 |
2006年 | 870篇 |
2005年 | 878篇 |
2004年 | 780篇 |
2003年 | 618篇 |
2002年 | 588篇 |
2001年 | 180篇 |
2000年 | 160篇 |
1999年 | 148篇 |
1998年 | 167篇 |
1997年 | 184篇 |
1996年 | 210篇 |
1995年 | 126篇 |
1994年 | 151篇 |
1993年 | 144篇 |
1992年 | 106篇 |
1991年 | 105篇 |
1990年 | 88篇 |
1989年 | 74篇 |
1988年 | 87篇 |
1987年 | 79篇 |
1986年 | 68篇 |
1985年 | 123篇 |
1984年 | 115篇 |
1983年 | 76篇 |
1982年 | 89篇 |
1981年 | 108篇 |
1980年 | 94篇 |
1979年 | 79篇 |
1978年 | 64篇 |
1977年 | 53篇 |
1976年 | 51篇 |
1975年 | 47篇 |
1974年 | 47篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
L. Erlandsen G. Schenck H. Graf R. Wasicky G. Stern M. Zimet W. Schreber W. Hoffmann F. Schoofs V. F. Stewart H. J. Wollner J. R. Matchett und H. Quéré 《Fresenius' Journal of Analytical Chemistry》1940,120(3-4):147-151
Ohne Zusammenfassung 相似文献
53.
Raj Gandhi Kamales Kar S. Uma Sankar Abhijit Bandyopadhyay Rahul Basu Pijushpani Bhattacharjee Biswajoy Brahmachari Debrupa Chakraborti M. Chaudhury J. Chaudhury Sandhya Choubey E. J. Chun Atri Desmukhya Anindya Datta Gautam Dutta Sukanta Dutta Anjan Giri Sourendu Gupta Srubabati Goswami Namit Mahajan H. S. Mani A. Mukherjee Biswarup Mukhopadhyaya S. N. Nayak M. Randhawa Subhendu Rakshit Asim K. Ray Amitava Raychaudhuri D. P. Roy Probir Roy Suryadeep Roy Shiv Sethi G. Sigl Arunansu Sil N. Nimai Singh Mark Vagins Urjit Yagnik 《Pramana》2003,60(2):405-409
This is the report of neutrino and astroparticle physics working group at WHEPP-7. Discussions and work on CP violation in
long baseline neutrino experiments, ultra high energy neutrinos, supernova neutrinos and water Cerenkov detectors are discussed. 相似文献
54.
Mark P. WattersonAlison A. Edwards John A. LeachMartin D. Smith Osamu IchiharaGeorge W.J. Fleet 《Tetrahedron letters》2003,44(31):5853-5857
Efficient syntheses of all diastereomers of methyl 2,5-anhydro-3-deoxy-hexonate from mannono- or gulono-lactones provide precursors for C-nucleosides of 2-deoxyribose and for THF-templated γ- and δ-amino acids. 相似文献
55.
56.
Stewart S. J. Mercader R. C. Punte G. Desimoni J. Cernicchiaro G. Scorzelli R. B. 《Hyperfine Interactions》2004,158(1-4):89-93
In this paper we analyze trend of EFG values measured at Cd impurity in a group of semiconducting delafossites with chemical
formula CuBO2 (B = Al, Fe, Cr, Nd). We conclude that this trend reveals one of the most subtle details in electronic spectrum of the compounds:
if impurity states are formed within or out of the band gap. In CuAlO2 and CuFeO2 the Cd EFG exhibits larger value than in CuCrO2 and CuNdO2, when Cd substitutes the Cu atom. This occurs because in the first two compounds the Cd forms shallow band within the gap,
and in the second two compounds does not. When Cd occupies the B position it exhibits almost the same EFG in all delafossites.
In this case, Cd does not form its states within the gap in none of the compounds. To arrive to these conclusions we analyzed
and calculated various systems (Cd-doped CuAlO2 and CuCrO2 compounds, fictitious molecules), using the FP-LAPW method. 相似文献
57.
Casey Chun Zhou Eric J. Stoner Kent D. Stewart L. Steven Hollis Edmund D. Matayoshi Gregory M. Brill 《Tetrahedron》2004,60(47):10611-10618
Oritavancin is a semi-synthetic glycopeptide antibiotic which is structurally related to vancomycin. When oritavancin bisphosphate is dried in vacuo with heat, a new compound forms. This new compound is stable only in the solid state and reverts to oritavancin in solution. Highly enriched samples of this compound were obtained by preparative HPLC and the structure of this compound was elucidated by using one and two-dimensional (1H and 13C) NMR spectroscopy in conjunction with computer-assisted molecular modeling. It has been determined that oritavancin adopts a conformation similar to that of vancomycin in solution, while the new compound is the unnatural R-AB-biaryl atropisomer of oritavancin. This is the first observation and isolation of an AB-biaryl atropisomer in an intact member of the vancomycin family of glycopeptide antibiotics. 相似文献
58.
Mark D. Roberts 《General Relativity and Gravitation》2004,36(11):2423-2431
The paths of stars in galaxies have circular velocity independent of their distance from the centre of the galaxy. Newtonian mechanics with a logarithmic potential has such paths. In relativity these paths can be taken to be geodesics and this requirement places a restricting equation on the spacetime metric. This equation has a non-unique spherically symmetric solution that in the Newtonian limit has a logarithmic potential. It also can be solved in terms of a conformal factor. In particular it has solutions which are conformal to the vacuum-Einstein solutions and such spacetimes are solutions to the vacuum-Bach equations. Therefore it is suggested that the Bach equations describe dynamics on galactic length scales. 相似文献
59.
We have prepared glucose and cellobiose conjugates at the phenolic 3- and hydroxylic 17-positions of the pure anti-estrogenic compound fulvestrant (ICI 182,780), which has recently been approved in the USA for the treatment of advanced postmenopausal breast cancer. Glycosylation at the 17-position was achieved most effectively using pivaloyl protection of the sugar imidates employed, which we found suppressed the competing transacylation reaction and led to improved yields of the product glycosides. 相似文献
60.
Using a Bostick Gun as a plasma source, we have been investigating the effects of a moving plasma front on the frequency of an incident R.F. signal. We have been able to measure frequency shifts of 10 MHz frequency with a 2.6 GHz signal. The density is such that the plasma frequency is well above the transmitter frequency 1.3 meters from the plasma source. No magnetic field is used. 相似文献