全文获取类型
收费全文 | 29587篇 |
免费 | 427篇 |
国内免费 | 39篇 |
专业分类
化学 | 25244篇 |
晶体学 | 43篇 |
力学 | 221篇 |
综合类 | 1篇 |
数学 | 2745篇 |
物理学 | 1799篇 |
出版年
2016年 | 241篇 |
2014年 | 293篇 |
2013年 | 519篇 |
2012年 | 391篇 |
2011年 | 422篇 |
2010年 | 293篇 |
2009年 | 295篇 |
2008年 | 422篇 |
2007年 | 390篇 |
2006年 | 422篇 |
2005年 | 420篇 |
2004年 | 340篇 |
2003年 | 343篇 |
2002年 | 344篇 |
2001年 | 239篇 |
2000年 | 238篇 |
1988年 | 269篇 |
1987年 | 320篇 |
1986年 | 268篇 |
1985年 | 465篇 |
1984年 | 434篇 |
1982年 | 369篇 |
1981年 | 306篇 |
1980年 | 547篇 |
1979年 | 495篇 |
1978年 | 1278篇 |
1977年 | 1077篇 |
1976年 | 460篇 |
1975年 | 322篇 |
1974年 | 262篇 |
1973年 | 310篇 |
1972年 | 257篇 |
1970年 | 235篇 |
1968年 | 281篇 |
1967年 | 274篇 |
1966年 | 298篇 |
1965年 | 322篇 |
1964年 | 291篇 |
1962年 | 402篇 |
1960年 | 256篇 |
1959年 | 259篇 |
1958年 | 254篇 |
1956年 | 302篇 |
1955年 | 262篇 |
1937年 | 266篇 |
1936年 | 259篇 |
1935年 | 279篇 |
1934年 | 250篇 |
1933年 | 326篇 |
1930年 | 255篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Robin F. Weitkamp Beate Neumann Hans‐Georg Stammler Berthold Hoge 《Angewandte Chemie (International ed. in English)》2020,59(14):5494-5499
We report on the first examples of isolated silanol–silanolate anions, obtained by utilizing weakly coordinating phosphazenium counterions. The silanolate anions were synthesized from the recently published phosphazenium hydroxide hydrate salt with siloxanes. The silanol–silanolate anions are postulated intermediates in the hydroxide‐mediated polymerization of aryl and alkyl siloxanes. The silanolate anions are strong nucleophiles because of the weakly coordinating character of the phosphazenium cation, which is perceptible in their activity in polysiloxane depolymerization. 相似文献
2.
A profit-maximizing supply chain network design model with demand choice flexibility 总被引:1,自引:0,他引:1
Zuo-Jun Max Shen 《Operations Research Letters》2006,34(6):673-682
We present a profit-maximizing supply chain design model in which a company has flexibility in determining which customers to serve. The company may lose a customer to competition if the price it charges is too high. We show the problem formulation and solution algorithm, and discuss computational results. 相似文献
3.
Let A be a symmetric matrix of size n×n with entries in some (commutative) field K. We study the possibility of decomposing A into two blocks by conjugation by an orthogonal matrix T∈Matn(K). We say that A is absolutely indecomposable if it is indecomposable over every extension of the base field. If K is formally real then every symmetric matrix A diagonalizes orthogonally over the real closure of K. Assume that K is a not formally real and of level s. We prove that in Matn(K) there exist symmetric, absolutely indecomposable matrices iff n is congruent to 0, 1 or −1 modulo 2s. 相似文献
4.
5.
M. Brando N. Büttgen V. Fritsch J. Hemberger H. Kaps H.-A. Krug von Nidda M. Nicklas K. Pucher W. Trinkl A. Loidl E.W. Scheidt M. Klemm S. Horn 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(3):289-298
We present susceptibility, microwave resistivity, NMR and heat-capacity results for Li1-xZnx(V1-yTiy)2O4 with 0 ?
x
? 0.3 and 0 ?
y
? 0.3. For all doping levels the susceptibility curves can be fitted with a Curie-Weiss law. The paramagnetic Curie-Weiss temperatures
remain negative with an average value close to that of the pure compound Θ≈ - 36 K. Spin-glass anomalies are observed in the susceptibility, heat-capacity and NMR measurements for both type of dopants.
From the temperature dependence of the spin-lattice relaxation rate we found critical-dynamic behavior in the Zn doped compounds
at the freezing temperatures. For the Ti-doped samples two successive freezing transitions into disordered low-temperature
states can be detected. The temperature dependence of the heat capacity for Zn-doped compounds does not resemble that of canonical
spin glasses and only a small fraction of the total vanadium entropy is frozen at the spin-glass transitions. For pure LiV2O4 the spin-glass transition is completely suppressed. The temperature dependence of the heat capacity for LiV2O4 can be described using a nuclear Schottky contribution and the non-Fermi liquid model, appropriate for a system close to
a spin-glass quantum critical point. Finally an (
x
/
y
,
T
)-phase diagram for the low-doping regime is presented.
Received 16 March 2001 and Received in final form 30 October 2001 相似文献
6.
Ohne Zusammenfassung 相似文献
7.
Ohne Zusammenfassung 相似文献
8.
Ohne Zusammenfassung 相似文献
9.
E. Ritsert und W. Lenz 《Fresenius' Journal of Analytical Chemistry》1889,28(1):749-750
Ohne Zusammenfassung 相似文献
10.
Ohne Zusammenfassung
übersetzt von H. Kauffmann (Leipzig). 相似文献