全文获取类型
收费全文 | 2573篇 |
免费 | 48篇 |
国内免费 | 5篇 |
专业分类
化学 | 1656篇 |
晶体学 | 10篇 |
力学 | 25篇 |
数学 | 501篇 |
物理学 | 434篇 |
出版年
2020年 | 27篇 |
2019年 | 27篇 |
2016年 | 39篇 |
2015年 | 23篇 |
2014年 | 37篇 |
2013年 | 78篇 |
2012年 | 54篇 |
2011年 | 77篇 |
2010年 | 57篇 |
2009年 | 41篇 |
2008年 | 68篇 |
2007年 | 75篇 |
2006年 | 54篇 |
2005年 | 89篇 |
2004年 | 72篇 |
2003年 | 52篇 |
2002年 | 35篇 |
2001年 | 37篇 |
2000年 | 39篇 |
1999年 | 38篇 |
1998年 | 22篇 |
1996年 | 29篇 |
1995年 | 19篇 |
1994年 | 35篇 |
1993年 | 31篇 |
1992年 | 25篇 |
1991年 | 34篇 |
1990年 | 20篇 |
1989年 | 29篇 |
1988年 | 28篇 |
1987年 | 31篇 |
1986年 | 40篇 |
1985年 | 40篇 |
1984年 | 39篇 |
1983年 | 36篇 |
1982年 | 45篇 |
1981年 | 50篇 |
1980年 | 44篇 |
1979年 | 32篇 |
1978年 | 45篇 |
1977年 | 40篇 |
1976年 | 34篇 |
1975年 | 24篇 |
1974年 | 30篇 |
1973年 | 23篇 |
1972年 | 27篇 |
1971年 | 34篇 |
1970年 | 29篇 |
1968年 | 22篇 |
1967年 | 37篇 |
排序方式: 共有2626条查询结果,搜索用时 11 毫秒
1.
2.
Employing a cleavable carbohydrate–peptide linker, a new strategy for single-bead analysis of multivalent cyclic neoglycopeptides based on Edman degradation is described. Edman degradation of glycopeptides is hampered by the acid lability of the glycosidic bond and potential incompatibilities of phenylthiohydantoin (PTH) derivatives of glycosylated amino acids with PTH derivatives of the proteinogenic amino acids. To overcome this problem, carbohydrates are detached from the cyclopeptide templates before single-bead analysis, allowing for micro sequencing under routine conditions. With this strategy, application of multivalent cyclic neoglycopeptides in split-mix libraries with a subsequent screening process becomes possible for the first time. 相似文献
3.
4.
Roland A. Fischer Heinz-Josef Kneuper Wolfgang A. Hermann 《Journal of organometallic chemistry》1987,330(3):365-376
Hydrogenchalcogenido complexes of general composition (η5-C5R5)(CO)3M(EH) (R = H, CH3; M = Cr, Mo, W; E = S, Se) can be obtained by three different routes, sometimes in quite good yields. Thus, the sulfur and selenium derivatives can be synthesized by insertion of the respective elements into the metal-hydrogen bonds of the precursor compounds (η5-C5R5)(CO)3MH. This species also reacts with potassium selenocyanate to yield the hydrogenselenido derivatives (η5-C5R5)(CO)3M(SeH) which can also be obtained by treatment of the methyl complexes (η5-C5R5)(CO)3M(CH3 (M = Mo, W) with HBF4 and Li[SeH]. The corresponding hydrogentellurido compounds are probably formed by these preparative methods but appear to be quickly converted into either the dinuclear tellurium bridge products (μ-Te)[(η5-C5R5)(CO)3M]2 (M = Mo) or into the hydrido complexes (η5-C5R5)(CO)3MH (M= Mo, W) by release of elemental tellurium. 相似文献
5.
In an exterior domain Ω??n, n ? 2, we consider the generalized Stokes resolvent problem in Lq-space where the divergence g = div u and inhomogeneous boundary values u = ψ with zero flux ∫?Ωψ·N do = 0 may be prescribed. A crucial step in our approach is to find and to analyse the right space for the divergence g. We prove existence, uniqueness and a priori estimates of the solution and get new results for the divergence problem. Further, we consider the non-stationary Stokes system with non-homogeneous divergence and boundary values and prove estimates of the solution in L5(0, T;Lq(Ω)) for 1 < s, q < ∞. 相似文献
6.
Michaela Capellmann Hermann M. Bolt 《Fresenius' Journal of Analytical Chemistry》1992,342(4-5):462-466
Summary A reproducible method is described for the separation and simultaneous and specific quantitation of ascorbic acid and dehydroascorbic acid by ion-pairing reversed-phase HPLC with fluorometric detection. Copper sulphate and copper acetate were compared as oxidizing reagents for ascorbic acid and 1,2-diaminobenzene dihydrochloride and 1,2-diamino-3,4-dimethylbenzene dihydrochloride as derivatising reagents. The HPLC-method was applied to human plasma. The detection limit reaches 16 ng for ascorbic acid and 3 ng for dehydroascorbic acid. Sample preparation is carried out by solid phase extraction with a recovery of 98%; it is compared with conventional precipitation of plasma proteins by metaphosphoric acid. 相似文献
7.
8.
9.
Robert Hermann 《Acta Appl Math》1988,12(1):35-78
This paper will attempt to unify diverse material from physics and engineering in terms of differential forms on manifolds. A variational system will be defined by means of a scalar-valued differential form on a manifold and an ideal in the Grassmann algebra of differential forms on that manifold to serve as constraints. Two types of extremal submanifolds will be defined. The first-called the Euler-Lagrange extremals-will be defined by a method that is the generalization of the classical methods in the calculus of variations. The second—a generalization of a method used by Cartan in his treatise Leçons sur les invariants intégraux-will define extremals as integral submanifolds of an exterior differential system invariently attached to the variational system. As examples, the variational systems attached to string theories in Riemannian manifolds and Yang-Mills fields will be discussed from this differential form point of view. Finally, as application, the differential geometric properties and definition of energy will be presented from the differential form point of view.This work was supported by a grant from the Applied Mathematics program of the National Science Foundation. 相似文献
10.
Ohne Zusammenfassung7. Mitt.:Hermann Schmid undG. Bauer, Mh. Chem.96, 1508 (1965); dort ältere Mitt. dieser Reihe zitiert. 相似文献