全文获取类型
收费全文 | 298篇 |
免费 | 7篇 |
专业分类
化学 | 184篇 |
力学 | 2篇 |
数学 | 32篇 |
物理学 | 87篇 |
出版年
2023年 | 2篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 5篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 9篇 |
2012年 | 14篇 |
2011年 | 23篇 |
2010年 | 9篇 |
2009年 | 7篇 |
2008年 | 18篇 |
2007年 | 12篇 |
2006年 | 16篇 |
2005年 | 19篇 |
2004年 | 19篇 |
2003年 | 6篇 |
2002年 | 15篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 8篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 7篇 |
1959年 | 1篇 |
1924年 | 1篇 |
1920年 | 2篇 |
1912年 | 1篇 |
1911年 | 1篇 |
1907年 | 1篇 |
排序方式: 共有305条查询结果,搜索用时 31 毫秒
41.
42.
Peter J. Slater 《Discrete Mathematics》1979,25(1):65-74
Consider a collection of disjoint paths in graph G such that every vertex is on one of these paths. The size of the smallest such collection is denoted i(G). A procedure for forming such collections is established. Restricting attention to trees, the range of values for the sizes of the collections obtained is examined, and a constructive characterization of trees T for which one always obtains a collection of size i(T) is presented. 相似文献
43.
Peter J. Slater 《Discrete Applied Mathematics》1981,3(3):187-192
An ordered n-tuple (vi1,vi2,…,vin) is called a sequential labelling of graph G if {vi1,vi2,…,vin} = V(G) and the subgraph induced by {vi1,vi2,…, vij} is connected for 1≤j≤n. Let σ(v;G) denote the number of sequential labellings of G with vi1=v. Vertex v is defined to be an accretion center of G if σ is maximized at v. This is shown to generalize the concept of a branch weight centroid of a tree since a vertex in a tree is an accretion center if and only if it is a centroid vertex. It is not, however, a generalization of the concept of a median since for a general graph an accretion center is not necessarily a vertex of minimum distance. A method for computing σ(v;G) based upon edge contractions is described. 相似文献
44.
T.M. Hattox J.B. Conklin J.C. Slater S.B. Trickey 《Journal of Physics and Chemistry of Solids》1973,34(10):1627-1638
Self-consistent spin-polarized APW calculations have been performed to determine the energy band structure of metallic vanadium in an assumed ferromagnetic b.c.c. structure as a function of lattice parameter. The statistical exchange (‘Xα’) and muffin-tin approximations were used. At each lattice parameter for which a calculation was performed, the Xα cohesive energy, the pressure, and the magnetization were calculated. The calculated cohesive energy and pressure agree fairly well with experiment. The calculations also correctly predict the absence of a magnetic moment for vanadium at its equilibrium lattice constant. However, a nonmagnetic-to-magnetic transition is found to occur abruptly at a lattice constant which is about a factor of 1·25 larger than the equilibrium value, and which is in good qualitative agreement with the appearance of a local magnetic moment in certain vanadium alloys. 相似文献
45.
Peter J. Slater 《Journal of Graph Theory》1982,6(1):89-92
As counterexamples to a conjecture of Randi?, pairs of nonisomorphic trees with the same collections of distance degree sequences are presented. 相似文献
46.
We examine the problem of embedding a graph H as the center of a supergraph G, and we consider what properties one can restrict G to have. Letting A(H) denote the smallest difference ∣V(G)∣ - ∣V(H)∣ over graphs G having center isomorphic to H it is demonstrated that A(H) ≤ 4 for all H, and for 0 ≤ i ≤ 4 we characterize the class of trees T with A(T) = i. for n ≥ 2 and any graph H, we demonstrate a graph G with point and edge connectivity equal to n, with chromatic number X(G) = n + X(H), and whose center is isomorphic to H. Finally, if ∣V(H)∣ ≥ 9 and k ≥ ∣V(H)∣ + 1, then for n sufficiently large (with n even when k is odd) we can construct a k-regular graph on n vertices whose center is isomorphic to H. 相似文献
47.
P. Krolak R. A. Briere E. Cheu D. A. Harris K. S. McFarland A. Roodman B. Schwingenheuer S. V. Somalwar Y. W. Wah B. Winstein R. WinstonK. Arisaka D. Roberts W. Slater M. WeaverA. R. BarkerE. C. Swallow G. J. Bock R. Coleman M. Crisler J. Enagonio R. Ford Y. B. Hsiung D. A. Jensen E. Ramberg R. TschirhartE. M. Collins G. D. GollinT. Nakaya T. YamanakaP. Gu P. Haas W. P. Hogan S. K. Kim J. N. Matthews S. S. Myung S. Schnetzer G. B. ThomsonY. Zou 《Physics letters. [Part B]》1994,320(3-4):407-410
A FNAL E799 Collaboration has carried out a search for the lepton-family number violating decay π0 → μ±e using π0's produced from KL → π0π0π0 decays in flight. No events were observed. Assuming that lepton-family number violation is charge independent, the 90% confidence level upper limit on was determined to be 8.6 × 10−9. 相似文献
48.
Slater JW D'Alessandro DM Keene FR Steel PJ 《Dalton transactions (Cambridge, England : 2003)》2006,(16):1954-1962
The dinuclear bis(2,2'-bipyridine)ruthenium complex of 4,5-di(2-pyridyl)imidazolate has been prepared and separated into its (meso and rac) diastereoisomers. The 2-phenyl substituted analogue forms the meso isomer selectively. All three complexes have been characterised by 1H NMR and X-ray crystallography. Electrochemical measurements and spectroelectrochemistry of the mixed-valence states reveal strong metal-metal interactions and IVCT bands that are highly dependent on the electrolyte. 相似文献
49.
Abouzaid E Arenton M Barker AR Bellantoni L Bellavance A Blucher E Bock GJ Cheu E Coleman R Corcoran MD Cox B Erwin AR Escobar CO Glazov A Golossanov A Gomes RA Gouffon P Hsiung YB Jensen DA Kessler R Kotera K Ledovskoy A McBride PL Monnier E Nguyen H Niclasen R Ii DG Ping H Ramberg EJ Ray RE Ronquest M Santos E Slater W Smith D Solomey N Swallow EC Toale PA Tschirhart R Wah YW Wang J White HB Whitmore J Wilking MJ Winstein B Winston R Wolfe C Worcester ET Worcester M Yamanaka T Zimmerman ED 《Physical review letters》2008,100(13):131803
The Fermilab KTeV experiment has searched for lepton-flavor-violating decays of the K(L) meson in three decay modes. We observe no events in the signal region for any of the modes studied, and we set the following upper limits for their branching ratios at the 90% C.L.: BR(K(L) --> pi(0) micro(+/-) e(-/+)) <7.6 x 10(-11); BR(K(L) --> pi(0)pi(0) micro(+/-) e(-/+)) <1.7 x 10(-10); BR(pi(0) --> micro(+/-) e(-/+)) <3.6 x 10(-10). This result represents a factor of 82 improvement in the branching ratio limit for K(L) --> pi(0) micro(+/-) e(-/+) and is the first reported limit for K(L) --> pi(0)pi(0) micro(+/-) e(-/+). 相似文献
50.
Mark P. Stockham Alice Griffiths Dr. Bo Dong Prof. Peter R. Slater 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(6):e202103442
Lithium garnets are promising solid-state electrolytes for next-generation lithium-ion batteries. These materials have high ionic conductivity, a wide electrochemical window and stability with Li metal. However, lithium garnets have a maximum limit of seven lithium atoms per formula unit (e.g., La3Zr2Li7O12), before the system transitions from a cubic to a tetragonal phase with poor ionic mobility. This arises from full occupation of the Li sites. Hence, the most conductive lithium garnets have Li between 6–6.55 Li per formula unit, which maintains the cubic symmetry and the disordered Li sub-lattice. The tetragonal phase, however, forms the highly conducting cubic phase at higher temperatures, thought to arise from increased cell volume and entropic stabilisation permitting Li disorder. However, little work has been undertaken in understanding the controlling factors of this phase transition, which could enable enhanced dopant strategies to maintain room temperature cubic garnet at higher Li contents. Here, a series of nine tetragonal garnets were synthesised and analysed by variable temperature XRD to understand the dependence of site substitution on the phase transition temperature. Interestingly the octahedral site cation radius was identified as the key parameter for the transition temperature with larger or smaller dopants altering the transition temperature noticeably. A site substitution was, however, found to make little difference irrespective of significant changes to cell volume. 相似文献