全文获取类型
收费全文 | 332篇 |
免费 | 16篇 |
国内免费 | 1篇 |
专业分类
化学 | 227篇 |
晶体学 | 1篇 |
力学 | 8篇 |
数学 | 54篇 |
物理学 | 59篇 |
出版年
2023年 | 6篇 |
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 11篇 |
2019年 | 7篇 |
2018年 | 5篇 |
2017年 | 9篇 |
2016年 | 13篇 |
2015年 | 9篇 |
2014年 | 11篇 |
2013年 | 36篇 |
2012年 | 28篇 |
2011年 | 21篇 |
2010年 | 15篇 |
2009年 | 6篇 |
2008年 | 19篇 |
2007年 | 20篇 |
2006年 | 14篇 |
2005年 | 11篇 |
2004年 | 12篇 |
2003年 | 10篇 |
2002年 | 9篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1974年 | 1篇 |
排序方式: 共有349条查询结果,搜索用时 15 毫秒
1.
José A. Anquela Teresa Cortés Miguel Gómez-Lozano Mercedes Siles-Molina 《Acta Mathematica Hungarica》2004,103(3):177-196
We investigate the basic properties of the different socles that can be considered in not necessarily semiprime associative
systems. Among other things, we show that the socle defined as the sum of minimal (or minimal and trivial) inner ideals is
always an ideal. When trivial inner ideals are included, this inner socle contains the socles defined in terms of minimal
left or right ideals.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
2.
J. Cortés 《Colloid and polymer science》1991,269(11):1184-1189
At the low temperature limit, the effect on the size and shape factors of the adsorbate molecule is shown in a simulation of a monomolecular phase adsorbed on a heterogeneous surface. This factor is reflected both in the theoretical distribution of the adsorption energies and the packing of the adsorbed phase. 相似文献
3.
R. Acevedo T. Meruane E. Cortés S. O. Vasquez C. D. Flint 《Theoretical chemistry accounts》1994,88(2):99-110
Summary A theoretical model to calculate the vibronic intensities induced by the odd vibrational modes in centrosymmetric lanthanide complexes is developed and applied to octahedral complex ions, LnX
6
3–
, such as occur in the hexachloroelpasolites Cs2NaLnCl6. Both the crystal field and the ligand polarisation contributions are evaluated using a standard set of symmetry coordinates. For the crystal field term a truncated expansion of the intermediates states is employed rather than the more conventional closure approximation. Special care is necessary to ensure that the phases of the contributions are correctly determined since the cross-term between the ligand polarisation and crystal field contributions is signed. General equations applicable to anyf
n
complex ion are derived and an example of their application to the PrCl
6
3–
ion is given The agreement with experiment is satisfactory. 相似文献
4.
5.
We classify extended Poincaré Lie superalgebras and Lie algebras of any signature (p, q), i.e. Lie superalgebras and 2-graded Lie algebras g = g0 + g1, where g0 = s0(V) + V is the (generalized) Poincaré Lie algebra of the pseudo Euclidean vector space V =
p, q
of signature (p, q) and g1 is a spin 1/2 s0(V)-module extended to a s0-module with kernel V.As a result of the classification, we obtain, if g1 = S is the spinor module, the numbers L
+(n, s) (resp. L
–(n, s)) of independent such Lie super algebras (resp. Lie algebras), which are periodic functions of the dimension n=p+q (mod 8) and the signature s=p–q (mod 8) and satisfy: L
+(–n, s)=L
–
(n, s).Supported by Max-Planck-Institut für Mathematik (Bonn).Supported by the Alexander von Humboldt Foundation, MSRI (Berkeley) and SFB 256 (Bonn University). 相似文献
6.
The coupled-column (LC-LC) system, consisting of a first column packed with internal surface reversed phase (ISRP) (50 x 4.6mm ID) and a Chrompack C18 (100 x 4.6 mm ID) as second column, allowed the simultaneous determination of five benzoylurea insecticides in dichloromethane (CH2Cl2) extracts of vegetable samples without any clean-up step. This system was combined with a photochemically induced fluorescence (PIF) post-column derivatization in order to provide strongly fluorescent photoproducts from the non-fluorescent benzoylureas. Limits of detection ranged from 0.21 to 0.98 microg L(-1) of pesticide (equivalent to 0.14-0.65 microg kg(-1) in vegetable samples) and limits of determination ranged from 4.0 to 10.0 microg L(-1) (equivalent to 2.7-6.7 microg kg(-1)). Linearity of the method was established between 2 and 1800 microg L(-1), depending upon the compound. Validation of the total method was performed by randomly analyzing recoveries of four vegetable samples (aubergine, cucumber, green bean, and tomato) spiked at two levels of concentration (10.0 and 33.3 microg kg(-1)). The combination of the LC-LC system with PIF detection provides a sensitive, selective, and rapid method for the determination of pesticides in vegetable samples at levels lower than the maximum residue levels (MRLs) established for these compounds by Spanish legislation. 相似文献
7.
Robin Zuluaga Jean-Luc Putaux Adriana Restrepo Iñaki Mondragon Piedad Gañán 《Cellulose (London, England)》2007,14(6):585-592
Cellulose microfibrils have been prepared from banana rachis using a combination of chemical and mechanical treatments. The
morphology and structure of the samples were characterized using transmission electron microscopy, atomic force microscopy,
and X-ray diffraction. Fourier-transformed infrared spectroscopy (FTIR) was used to characterize the chemical modifications
of the samples after each treatment. Suspensions of bundled or individualized 5-nm-wide microfibrils were obtained after homogenization
(PH) whereas an organosolv (PO) treatment resulted in shorter aggregates of parallel cellulose microcrystallites. The sharper
rings in the X-ray diffraction pattern of the PO-treated sample suggest a higher crystallinity due to a more efficient removal
of hemicelluloses and dissolution of amorphous zones by the acid treatment. Both microfibrils and microcrystals prepared by
both methods can be used as reinforcing filler in nanocomposite materials. 相似文献
8.
Cametti M Nissinen M Dalla Cort A Mandolini L Rissanen K 《Chemical communications (Cambridge, England)》2003,(19):2420-2421
Uranyl-salophen complexes endowed with aromatic side arms behave as very efficient ditopic receptors towards tetralkylammonium halides as a result of a combination of Lewis acid-base and cation-pi interactions. 相似文献
9.
Dalla Cort A Mandolini L Palmieri G Pasquini C Schiaffino L 《Chemical communications (Cambridge, England)》2003,(17):2178-2179
In complexes with the uranyl dication salophen ligands are highly puckered. This implies that non-symmetrically substituted uranyl-salophen derivatives exist in principle as a pair of enantiomers. However, due to easy disrotations about the bonds connecting the phenoxide units to the imine carbons, the rate of interconversion between enantiomeric forms of simple, sterically unhindered compounds is extremely fast. Bulky substituents in appropriate positions decrease the interconversion rate and make this novel type of inherent chirality detectable by 1H and 13C NMR. 相似文献
10.
E. Cortés N. Gras L. Muñoz V. Cassorla 《Journal of Radioanalytical and Nuclear Chemistry》1982,69(1-2):401-415
Seven trace elements were determined in milk formulas, powder milk and infant food. Instrumental neutron activation analysis
was used for the analysis of Fe, Zn, Co, Cr and Rb, while As and Cu content was determined using radiochemical neutron activation
analysis. Differences were found in the trace element content of foods of the same type. Milk formulas are comparable with
human milk according to the results obtained for the elements analyzed. The samples of powder cow's milk presented similar
concentrations of the elements studied. Liver with vegetables was found to have the highest Cu content. A meal prepared at
home, made of beef and fresh vegetables showed a higher trace element content than its similar commercial one. An estimation
of the daily intake of the elements analyzed was made and compared with minimum recommended daily ingestion. 相似文献