全文获取类型
收费全文 | 17931篇 |
免费 | 417篇 |
国内免费 | 320篇 |
专业分类
化学 | 2083篇 |
晶体学 | 100篇 |
力学 | 120篇 |
综合类 | 35篇 |
数学 | 14702篇 |
物理学 | 1628篇 |
出版年
2023年 | 51篇 |
2022年 | 125篇 |
2021年 | 91篇 |
2020年 | 139篇 |
2019年 | 471篇 |
2018年 | 471篇 |
2017年 | 291篇 |
2016年 | 242篇 |
2015年 | 230篇 |
2014年 | 482篇 |
2013年 | 1150篇 |
2012年 | 497篇 |
2011年 | 1153篇 |
2010年 | 880篇 |
2009年 | 1151篇 |
2008年 | 1320篇 |
2007年 | 1394篇 |
2006年 | 1036篇 |
2005年 | 717篇 |
2004年 | 633篇 |
2003年 | 592篇 |
2002年 | 455篇 |
2001年 | 362篇 |
2000年 | 369篇 |
1999年 | 435篇 |
1998年 | 408篇 |
1997年 | 283篇 |
1996年 | 394篇 |
1995年 | 370篇 |
1994年 | 353篇 |
1993年 | 289篇 |
1992年 | 238篇 |
1991年 | 153篇 |
1990年 | 165篇 |
1989年 | 143篇 |
1988年 | 101篇 |
1987年 | 106篇 |
1986年 | 89篇 |
1985年 | 132篇 |
1984年 | 96篇 |
1983年 | 75篇 |
1982年 | 100篇 |
1981年 | 97篇 |
1980年 | 73篇 |
1979年 | 50篇 |
1978年 | 64篇 |
1977年 | 52篇 |
1976年 | 49篇 |
1975年 | 18篇 |
1974年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
Differential calculus on quantized simple lie groups 总被引:1,自引:0,他引:1
Branislav Jurčo 《Letters in Mathematical Physics》1991,22(3):177-186
Differential calculi, generalizations of Woronowicz's four-dimensional calculus on SU
q
(2), are introduced for quantized classical simple Lie groups in a constructive way. For this purpose, the approach of Faddeev and his collaborators to quantum groups was used. An equivalence of Woronowicz's enveloping algebra generated by the dual space to the left-invariant differential forms and the corresponding quantized universal enveloping algebra, is obtained for our differential calculi. Real forms for q are also discussed. 相似文献
22.
We propose a method of calculating the heat kernel expansion of coset spaces. The five first coefficients of this expansion on symmetric spaces of dimension d8 are obtained. 相似文献
23.
Š. Porubský 《Periodica Mathematica Hungarica》1982,13(1):9-14
A necessary and sufficient condition for the group of isomorphisms involved in a factorization of a complete graph into isomorphic factors is established. 相似文献
24.
Richard Combes Marie-Noëlle Levelut Bernard Trémillon 《Journal of Electroanalytical Chemistry》1978,91(1):125-131
Reactions between cerium trichloride and oxide ions were studied in NaCl+KCl (1/1) at 1000°K, by potentiometry with a calcia-stabilized zirconia membrane electrode. Titration curves clearly demonstrated the existence of soluble cerium oxychloride (CeO+) and precipitated cerium oxide (Ce2O3), with respective dissociation constants 10?11 and 10?30 (molality scale). The corresponding conditional solubility diagram {log S (CeIII)=f(pO2?)} is presented and discussed. 相似文献
25.
Kuo-yuan Hung Renata Kowalczyk Ami Desai Margaret A. Brimble John F. Marshall Paul W. R. Harris 《Molecules (Basel, Switzerland)》2022,27(14)
A20FMDV2 is a 20-mer peptide that exhibits high selectivity and affinity for the tumour-related αvβ6 integrin that can compete with extracellular ligands for the crucial RGD binding site, playing a role as a promising αvβ6-specific inhibitor for anti-cancer therapies. Unfortunately, the clinical value of A20FMDV2 is limited by its poor half-life in blood caused by rapid renal excretion and its reported high susceptibility to serum proteases. The incorporation of poly (ethylene glycol) chains, coined PEGylation, is a well-established approach to improve the pharmacokinetic properties of drug molecules. Here, we report a systematic study on the incorporation of a varying number of ethylene glycol units (1–20) into the A20FMDV2 peptide to establish the effects of PEGylation size on the peptide stability in both rat serum and human plasma. In addition, the effect of acetyl and propionyl PEGylation handles on peptide stability is also described. Selected peptide analogues were assessed for integrin-αvβ6-targeted binding, showing good specificity and activity in vitro. Stability studies in rat serum established that all of the PEGylated peptides displayed good stability, and an A20FMDV2 peptide containing twenty ethylene glycol units (PEG20) was the most stable. Surprisingly, the stability testing in human plasma identified shorter PEGs (PEG2 and PEG5) as more resistant to degradation than longer PEGs, a trend which was also observed with affinity binding to integrin αvβ6. 相似文献
26.
以元素单质Pb片,Te粉,Se粉为原料,乙二胺为螯合剂,采用元素溶剂热反应合成出不同形貌的PbE(E=Te,Se)微晶.对所得反应物进行了X射线衍射分析,透射电镜(TEM)与扫描电镜(SEM)的分析,光致荧光光谱的表征.分析了反应条件对合成PbE(E=Te,Se)微晶的影响,讨论了其反应过程及机理.结果表明当反应温度为180℃时,反应12h可获得高度结晶的树枝状PbTe微晶以及立方状PbSe微晶. 相似文献
27.
28.
Deformed Hartree-Fock calculations are performed for some light nuclei in a large configuration space consisting of first
four major shells. The interaction employed is the modified Skyrme interaction in which the deformed density is replaced by
the band averaged scalar density that makes the Hamiltonian rotationally invariant rendering the spectroscopic calculations
feasible. It is shown that the introduction of density dependence spreads out the energy spectra and that the Skyrme variant
SIV which has a weak density dependence gives best overall agreement for energy spectra and the available data for the electromagnetic
properties of the nuclei studied. It is found that the maximum contribution to the energy of any state in the low lying spectrum
comes from thes-state attractive ands-state repulsive parts of the Skyrme interaction. It is also shown that when two-body density dependent version of Skyrme
interaction is used, the Koopmans theorem no longer holds. 相似文献
29.
K. Wetzel 《Isotopes in environmental and health studies》2013,49(3):125-126
In einem dynamischen System vollziehen sich kontinuierlich ablaufende Stoffwandlungen, deren Ausgangsstoffe dem System ständig zufließen und deren Folgeprodukte das System kontinuierlich verlassen. Es wird das Verhalten eines solchen Systems mit drei Pools bei Markierungsexperimenten untersucht. Die Ergebnisse dieser mathematischen Untersuchungen werden auf die Erforschung des Stickstoffstoffwechsels laktierender Rinder mit Hilfe des stabilen Isotops 15N angewandt. In diesem Fall enthält das dynamische System zwei kleine stoffwechselaktive Pools und einen großen, niclit intensiv am Stoffwechsel beteiligten Körpereiweiβ-Pool. 相似文献
30.
D. Haendel 《Isotopes in environmental and health studies》2013,49(12):405-406
Zur Klärung geologischer Prozesse werden in zunchmendem Maße die Isotopenvariationen des Stickstoffs herangezogen. Da der größte Teil des Stickstoffs der Gesteine in gebundener Form als Ammoniumstickstoff [1–6] vorliegt, kommt der Untersuchung der Isotopenvariationen desselben eine große Bedeutung zu. 相似文献