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991.
We consider functionals of the calculus of variations of the form F(u)= ∝01 f(x, u, u′) dx defined for u ε W1,∞(0, 1), and we show that the relaxed functional
with respect to weak W1,1(0, 1) convergence can be written as
, where the additional term L(u), called the Lavrentiev term, is explicitly identified in terms of F. 相似文献
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992.
Marina S. Fonari Yurii A. Simonov Victor Ch. Kravtsov Vladimir O. Gelmboldt Edward V. Ganin Yurii A. Popkov Larisa V. Ostapchuk 《Journal of inclusion phenomena and macrocyclic chemistry》1998,30(3):197-213
Novel complementary associations have been found in a crystalline ternarycomplex of the macrocyclic tetramine, [12]aneN4 (e.g. =1,4,7,10-tetraazacyclododecane, cyclen, L), hexafluorosilicate ions andwater (I). The final compound belongs to the host—guest type with themacrocycle as the host (H), the inorganic entity as a guest (G) and watermolecules. It was characterized by X-ray techniques, IR spectroscopy andthermogravimetric study. X-ray crystal analysis revealed that the structureis built of the charged entities, with a 3D-network uniting thequadriprotonated form of the macrocycle, hexafluorosilicate as counterionsand lattice water molecules viaN—H+...F-,N—H+...O(w),OH...F- and O—-H(w)...O(w)hydrogen bonds. The overall complex stoichiometry comprises fourSiF6
2- anions and seven water molecules per two[LH4]4+ cations. Crystals of (I) are monoclinic,space group P21/n with a = 14.585(3), b = 16.384(2), c =16.500(3) Å, = 92.84(3)°, V = 3938(1)Å3 and Z = 8 forC8H31F12N4O3.5Si2. 相似文献
993.
Vladimir A. Ogurtsov Pavel V. Dorovatovskii Yan V. Zubavichus Victor N. Khrustalev Artem N. Fakhrutdinov Sergei G. Zlotin Oleg A. Rakitin 《Tetrahedron letters》2018,59(32):3143-3146
An efficient synthesis of [1,2,5]oxadiazolo[3,4-d]pyridazine 1,5,6-trioxides (1) from 3,4-bis(hydroxyimino)methyl)-1,2,5-oxadiazole 2-oxides using a mixture of concentrated nitric and trifluoroacetic acids has been developed. The scope of the unconventional reaction was established. The 4,7-dinitro[1,2,5]oxadiazolo[3,4-d]pyridazine 1,5,6-trioxide 1f represents a new high energy compound, unfortunately with low thermal stability. The parent [1,2,5]oxadiazolo[3,4-d]pyridazine 1,5,6-trioxide 1c was studied by single-crystal X-ray diffraction analysis which revealed a planar molecule with an unusually long intracyclic NN bond of 1.668(5)?Å and unexpected exo-cyclic bond angles at the nitroxyl nitrogen atoms. In the crystal, the molecules of 1c are bound to each other by strong π-π stacking and CH?O hydrogen bonding interactions into a three-dimensional framework that results in a high crystal density of 1.833?gcm?3. 相似文献
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998.
Coline Canovas Dr. Mathieu Moreau Dr. Claire Bernhard Dr. Alexandra Oudot Mélanie Guillemin Prof. Franck Denat Dr. Victor Goncalves 《Angewandte Chemie (International ed. in English)》2018,57(33):10646-10650
Dual‐labeled biomolecules constitute a new generation of bioconjugates with promising applications in therapy and diagnosis. Unfortunately, the development of these new families of biologics is hampered by the technical difficulties associated with their construction. In particular, the site specificity of the conjugation is critical as the number and position of payloads can have a dramatic impact on the pharmacokinetics of the bioconjugate. Herein, we introduce dichlorotetrazine as a trivalent platform for the selective double modification of proteins on cysteine residues. This strategy is applied to the dual labeling of albumin with a macrocyclic chelator for nuclear imaging and a fluorescent probe for fluorescence imaging. 相似文献
999.
Matthew V. Vollmer Dr. Jing Xie Ryan C. Cammarota Dr. Victor G. Young Jr. Dr. Eckhard Bill Prof. Laura Gagliardi Prof. Connie C. Lu 《Angewandte Chemie (International ed. in English)》2018,57(26):7815-7819
Formal nickelate(?I) complexes bearing Group 13 metalloligands (M=Al and Ga) were isolated. These 17 e? complexes were synthesized by one‐electron reduction of the corresponding Ni0→MIII precursors, and were investigated by single‐crystal X‐ray diffraction, EPR spectroscopy, and quantum chemical calculations. Collectively, the experimental and computational data support: 1) the strengthening of the Ni?M bond upon one‐electron reduction, and 2) the delocalization of the unpaired spin across the Ni and M atoms. An intriguing electronic configuration is revealed where three valence electrons occupy two σ‐type bonding interactions: Ni(3d )2→M and σ‐(Ni?M)1. The latter is an unusual Ni?M σ‐bonding molecular orbital that comprises primarily the Ni 4pz and M npz/ns atomic orbitals. 相似文献
1000.
Periodically Arranged Arrays of Dendritic Pt Nanospheres Using Cage‐Type Mesoporous Silica as a Hard Template 下载免费PDF全文
Kenya Kani Dr. Victor Malgras Dr. Bo Jiang Dr. Md. Shahriar A. Hossain Prof. Saad M. Alshehri Prof. Tansir Ahamad Dr. Rahul R. Salunkhe Dr. Zhenguo Huang Prof. Yusuke Yamauchi 《化学:亚洲杂志》2018,13(1):106-110
Dendritic Pt nanospheres of 20 nm diameter are synthesized by using a highly concentrated surfactant assembly within the large‐sized cage‐type mesopores of mesoporous silica (LP‐FDU‐12). After diluting the surfactant solution with ethanol, the lower viscosity leads to an improved penetration inside the mesopores. After Pt deposition followed by template removal, the arrangement of the Pt nanospheres is a replication from that of the mesopores in the original LP‐FDU‐12 template. Although it is well known that ordered LLCs can form on flat substrates, the confined space inside the mesopores hinders surfactant self‐organization. Therefore, the Pt nanospheres possess a dendritic porous structure over the entire area. The distortion observed in some nanospheres is attributed to the close proximity existing between neighboring cage‐type mesopores. This new type of nanoporous metal with a hierarchical architecture holds potential to enhance substance diffusivity/accessibility for further improvement of catalytic activity. 相似文献