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111.
Let A be a finite-dimensional algebra over a field k. The derived Picard group DPic
k
(A) is the group of triangle auto-equivalences of D>
b( mod A) induced by two-sided tilting complexes. We study the group DPic
k
(A) when A is hereditary and k is algebraically closed. We obtain general results on the structure of DPic
k
, as well as explicit calculations for many cases, including all finite and tame representation types. Our method is to construct a representation of DPic
k
(A) on a certain infinite quiver irr. This representation is faithful when the quiver of A is a tree, and then DPic
k
(A) is discrete. Otherwise a connected linear algebraic group can occur as a factor of DPic
k
(A). When A is hereditary, DPic
k
(A) coincides with the full group of k-linear triangle auto-equivalences of Db( mod A). Hence, we can calculate the group of such auto-equivalences for any triangulated category D equivalent to Db( mod A. These include the derived categories of piecewise hereditary algebras, and of certain noncommutative spaces introduced by Kontsevich and Rosenberg. 相似文献
112.
Jun-ichi Miyachi 《Proceedings of the American Mathematical Society》2000,128(8):2233-2242
We give new construction of injective resolutions of complexes and bimodules. Applying this construction to an injective resolution of a Noetherian ring, we construct a -embedding cogenerator for the category of modules of projective dimension . Moreover, for a Noetherian projective -algebra , we show that satisfies the Auslander condition if and only if the flat dimension of every -module is equal to or larger than the one of the injective hull .
113.
114.
115.
116.
117.
118.
Koji Nuida Satoshi Fujitsu Manabu Hagiwara Takashi Kitagawa Hajime Watanabe Kazuto Ogawa Hideki Imai 《Designs, Codes and Cryptography》2009,52(3):339-362
It has been proven that the code lengths of Tardos’s collusion-secure fingerprinting codes are of theoretically minimal order
with respect to the number of adversarial users (pirates). However, the code lengths can be further reduced as some preceding
studies have revealed. In this article we improve a recent discrete variant of Tardos’s codes, and give a security proof of
our codes under an assumption weaker than the original Marking Assumption. Our analysis shows that our codes have significantly
shorter lengths than Tardos’s codes. For example, when c = 8, our code length is about 4.94% of Tardos’s code in a practical setting and about 4.62% in a certain limit case. Our
code lengths for large c are asymptotically about 5.35% of Tardos’s codes.
A part of this work was presented at 17th Applied Algebra, Algebraic Algorithms, and Error Correcting Codes (AAECC-17), Bangalore,
India, December 16–20, 2007. 相似文献
119.
Y. Nakanishi Y. Kitagawa Y. Shigeta T. Saito T. Matsui H. Miyachi T. Kawakami M. Okumura K. Yamaguchi 《Polyhedron》2009,28(9-10):1714-1717
The origin of a ferromagnetic interaction between Cu2+ ions in the Cu2+–DNA system which reported by Tanaka et al. is examined by using DFT calculations. In order to consider effects of an entanglement and a dis-entanglement of the double helix chain, three types of structural disorders i.e. distance, rotation angle and discrepancy in XY-plane, are considered in the model dimer structure. All calculated results show that Jab values are weak anti-ferromagnetic couplings. Boltzmann distribution simulation indicates that the high spin (HS) species exist 21% at 1.5 K by thermal excitation within the model structure. 相似文献
120.
Ayumi Ishii Shinobu Kishi Hideki Ohtsu Toshifumi Iimori Takakazu Nakabayashi Nobuhiro Ohta Naoto Tamai Milan Melnik Miki Hasegawa Yuzo Shigesato 《Chemphyschem》2007,8(9):1345-1351
The electronic and structural behaviour of a Pr(III) complex with 4,7-diphenyl-1,10-phenanthroline, [Pr(bathophen)(2)(NO(3))(3)], is investigated with respect to the effect of configuration changes on the Pr(III) centre. [Pr(bathophen)(2)(NO(3))(3)] luminesces from the excited states of the ligand and the metal ion. The fluorescence, ff-emission ((1)D(2)-->(3)H(4)), and phosphorescence bands appear at 394, 608.2 and 482 nm, respectively, in the solid state. In acetonitrile, the complex also shows multiple emissions. From the time-resolved emission and the lifetime measurements, the excitation energy-transfer in [Pr(bathophen)(2)(NO(3))(3)] is clarified, that is, the upper excited triplet level of the ligand acts as an energy donor, while the (1)D(2) levels of Pr(III) is the acceptor. Additionally, the emission phenomena of the complex can be modified by molecular distortion, particularly by rotation of the phenyl groups in the ligand. 相似文献