全文获取类型
收费全文 | 1535篇 |
免费 | 42篇 |
国内免费 | 11篇 |
专业分类
化学 | 1012篇 |
晶体学 | 9篇 |
力学 | 17篇 |
数学 | 266篇 |
物理学 | 284篇 |
出版年
2022年 | 14篇 |
2021年 | 28篇 |
2020年 | 15篇 |
2019年 | 15篇 |
2018年 | 16篇 |
2017年 | 14篇 |
2016年 | 40篇 |
2015年 | 35篇 |
2014年 | 56篇 |
2013年 | 84篇 |
2012年 | 64篇 |
2011年 | 80篇 |
2010年 | 48篇 |
2009年 | 50篇 |
2008年 | 70篇 |
2007年 | 75篇 |
2006年 | 85篇 |
2005年 | 80篇 |
2004年 | 57篇 |
2003年 | 45篇 |
2002年 | 46篇 |
2001年 | 22篇 |
2000年 | 27篇 |
1999年 | 18篇 |
1998年 | 21篇 |
1997年 | 11篇 |
1996年 | 21篇 |
1995年 | 15篇 |
1994年 | 20篇 |
1993年 | 15篇 |
1992年 | 22篇 |
1991年 | 25篇 |
1990年 | 26篇 |
1989年 | 13篇 |
1988年 | 12篇 |
1987年 | 18篇 |
1986年 | 12篇 |
1985年 | 24篇 |
1984年 | 14篇 |
1983年 | 11篇 |
1982年 | 17篇 |
1981年 | 14篇 |
1980年 | 18篇 |
1979年 | 13篇 |
1978年 | 17篇 |
1977年 | 23篇 |
1976年 | 17篇 |
1975年 | 12篇 |
1973年 | 11篇 |
1936年 | 6篇 |
排序方式: 共有1588条查询结果,搜索用时 62 毫秒
71.
Mass action type deterministic kinetic models of ion channels are usually constructed in such a way as to obey the principle of detailed balance (or, microscopic reversibility) for two reasons: first, the authors aspire to have models harmonizing with thermodynamics, second, the conditions to ensure detailed balance reduce the number of reaction rate coefficients to be measured. We investigate a series of ion channel models which are asserted to obey detailed balance, however, these models violate mass conservation and in their case only the necessary conditions (the so-called circuit conditions) are taken into account. We show that ion channel models have a very specific structure which makes the consequences true in spite of the imprecise arguments. First, we transform the models into mass conserving ones, second, we show that the full set of conditions ensuring detailed balance (formulated by Feinberg) leads to the same relations for the reaction rate constants in these special cases, both for the original models and the transformed ones. 相似文献
72.
73.
74.
Dr. Azusa Kondoh Dipl.‐Chem. Alexander Arlt Barbara Gabor Prof. Alois Fürstner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(24):7731-7738
The lichen‐derived glycoconjugate gobienine A is structurally more complex than most glycolipids isolated from higher plants by virtue of the all‐cis substituted γ‐lactone substructure embedded into its macrocyclic frame. A concise entry into this very epimerization‐prone and hence challenging structural motif is presented, which relies on an enantioselective cyanohydrin formation, an intramolecular Blaise reaction, a palladium‐catalyzed alkoxycarbonylation, and a diastereoselective hydrogenation of the tetrasubstituted alkene in the resulting butenolide. This strategy, in combination with ring‐closing olefin metathesis for the formation of the macrocyclic perimeter, allowed the proposed structure of gobienine A ( 1 ) to be formed in high overall yield. The recorded spectral data show that the structure originally attributed to gobienine A is incorrect and that it is not the epimerization‐prone ester site on the butanolide ring that is the locus of misassignment; rather, the discrepancy must be more profound. 相似文献
75.
Numerical Algorithms - This paper describes a new MATLAB software package of iterative regularization methods and test problems for large-scale linear inverse problems. The software package, called... 相似文献
76.
Omer A. Akrawi Gergő Z. Nagy Tamás Patonay Alexander Villinger Peter Langer 《Tetrahedron letters》2012,53(26):3206-3209
Suzuki–Miyaura reactions of 4-trifluoromethylsulfonyloxy-6-bromocoumarin provide a convenient access to arylated coumarins. The reactions proceed with excellent chemoselectivity in favour of position 4. 相似文献
77.
78.
79.
Miklós Nagy László Szöllösi Sándor Kéki Rudolf Faust Miklós Zsuga 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(4):331-338
A series of amphiphilic polyisobutylene-block-poly(vinyl alcohol) (PIB-b-PVA) copolymers of constant PIB and varying PVA block length was synthesized by living carbocationic polymerization and their solution behavior was studied. The synthesis involved the preparation of polyisobutylene-b-poly(tert.-butyl vinyl ether) followed by hydrolysis with hydrogen bromide. The copolymers were characterized by gel permeation chromatography, 1H-NMR, and MALDI-TOF MS methods. The micellization behavior of the copolymers was investigated in aqueous media by direct dissolution and dialysis using static and dynamic light scattering. The critical micelle concentration, micelle size, aggregation number, and micelle shape were determined. The ability of the aggregates as drug carrying nanodevices was also investigated by doping them with indomethacin. UV-Vis measurements showed that the solubility of indomethacine increased significantly. Our findings suggest that the solubility is largely dependent upon the block segment ratios. 相似文献
80.
Dr. Tran Quang Hung Dr. Ferial Terki Dr. Souleymane Kamara Mourad Dehbaoui Prof. Salam Charar Brajalal Sinha Prof. CheolGi Kim Dr. Philippe Gandit Il'ya A. Gural'skiy Dr. Gabor Molnar Dr. Lionel Salmon Dr. Helena J. Shepherd Dr. Azzedine Bousseksou 《Angewandte Chemie (International ed. in English)》2013,52(4):1058-1058