全文获取类型
收费全文 | 2875篇 |
免费 | 50篇 |
国内免费 | 8篇 |
专业分类
化学 | 1465篇 |
晶体学 | 21篇 |
力学 | 71篇 |
数学 | 306篇 |
物理学 | 1070篇 |
出版年
2019年 | 20篇 |
2016年 | 36篇 |
2015年 | 39篇 |
2014年 | 53篇 |
2013年 | 67篇 |
2012年 | 96篇 |
2011年 | 116篇 |
2010年 | 49篇 |
2009年 | 48篇 |
2008年 | 120篇 |
2007年 | 101篇 |
2006年 | 120篇 |
2005年 | 126篇 |
2004年 | 88篇 |
2003年 | 67篇 |
2002年 | 64篇 |
2001年 | 63篇 |
2000年 | 49篇 |
1999年 | 33篇 |
1998年 | 29篇 |
1997年 | 43篇 |
1996年 | 68篇 |
1995年 | 62篇 |
1994年 | 58篇 |
1993年 | 74篇 |
1992年 | 44篇 |
1991年 | 25篇 |
1990年 | 31篇 |
1989年 | 37篇 |
1988年 | 34篇 |
1987年 | 31篇 |
1986年 | 36篇 |
1985年 | 27篇 |
1984年 | 31篇 |
1983年 | 26篇 |
1982年 | 27篇 |
1981年 | 23篇 |
1980年 | 30篇 |
1979年 | 20篇 |
1978年 | 25篇 |
1976年 | 20篇 |
1975年 | 30篇 |
1974年 | 20篇 |
1973年 | 21篇 |
1971年 | 19篇 |
1969年 | 19篇 |
1968年 | 50篇 |
1967年 | 117篇 |
1966年 | 110篇 |
1965年 | 71篇 |
排序方式: 共有2933条查询结果,搜索用时 15 毫秒
991.
992.
Jianzhao Liu Adam J. P. Bauer Bingbing Li 《Macromolecular rapid communications》2014,35(17):1503-1508
Solvent vapor annealing (SVA) is originally developed to attain equilibrium nanostructures from microphase‐separated block polymer thin films. Interestingly, by carefully choosing a solvent vapor that can selectively mobilize the amorphous chains of a semicrystalline polymer while preserving the integrity of its crystalline structure, this study demonstrates that the SVA method can also be utilized to introduce hierarchical structures onto semicrystalline polymer‐based materials. This study on electrospun poly(ε‐caprolactone) (PCL) fibers clearly shows that acetone, a poor solvent for PCL, can effectively delocalize the amorphous chains and redeposit them onto the pre‐existing crystal edges, giving rise to secondary nanostructures inscribed onto the PCL fibers. In the past decade, various fiber fabrication methods and numerous fiber products are reported. The easy one‐step approach reported here provides new insight into the design and fabrication of structurally hierarchical polymeric materials.
993.
Sebastian Bauer Patrizio Neff Dirk Pauly Gerhard Starke 《Comptes Rendus Mathematique》2014,352(2):163-166
We present some Poincaré-type inequalities for quadratic matrix fields with applications e.g. in gradient plasticity or fluid dynamics. In particular, applications to the pseudostress–velocity formulation of the stationary Stokes problem and to infinitesimal gradient plasticity are discussed. 相似文献
994.
Wolfram Bauer Crispin Herrera Yañez Nikolai Vasilevski 《Integral Equations and Operator Theory》2014,78(2):271-300
We study the so-called radial operators, and in particular radial Toeplitz operators, acting on the standard weighted Bergman space on the unit ball in ${\mathbb{C}^n}$ . They turn out to be diagonal with respect to the standard monomial basis, and the elements of their eigenvalue sequences depend only on the length of multi-indexes enumerating basis elements. We explicitly characterize the eigenvalue sequences of radial Toeplitz operators by giving a solution for the weighted extension of the classical Hausdorff moment problem, and show that the norm closure of the set of all radial Toeplitz operators with bounded measurable radial symbols coincides with the C*-algebra generated by these Toeplitz operators and is isomorphic and isometric to the C*-algebra of sequences that slowly oscillate in the sense of Schmidt. 相似文献
995.
Stephan Schlamp Peter Thoma Tobias Bauer Rhett Kempe Birgit Weber 《无机化学与普通化学杂志》2013,639(10):1763-1767
The synthesis of two new Schiff base like ligands containing a 1, 8‐diaminonaphthalene unit in order to improve π–π interactions between the molecules is described. The corresponding iron(II), copper(II), and nickel(II) complexes were synthesized and characterized using NMR spectroscopy, magnetic measurements, and for the iron(II) complex X‐ray structure analysis. The crystal structure shows a strongly saddle shaped ligand. In contrast to related complexes with a phenylene unit that prefer an octahedral coordination sphere, this complex crystallizes pentacoordinate. The keto‐group of a neighboring complex serves as axial ligand resulting in the formation of infinite chains. Magnetic susceptibility measurements reveal nearly ideal curie behavior for the copper(II) and the iron(II) complex. 相似文献
996.
Dr. Jürgen Bauer Prof. Dr. Holger Braunschweig Dr. Rian D. Dewhurst Dr. Krzysztof Radacki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(27):8797-8805
We herein report detailed investigations into the interaction of Lewis acidic fluoroboranes, for example BF2Pf (Pf=perfluorophenyl) and BF2ArF (ArF=3,5‐bis(trifluoromethyl)phenyl), with Lewis basic platinum complexes such as [Pt(PEt3)3] and [Pt(PCy3)2] (Cy=cyclohexyl). Two presumed Lewis adducts could be identified in solution and corresponding secondary products of these Lewis adducts were characterized in the solid state. Furthermore, the concept of frustrated Lewis pairs (FLP) was applied to the activation of ethene in the system [Pt(BPf3)(CH2CH2)(dcpp)] (dcpp=1,3‐bis(dicyclohexylphosphino)propane; Pf=perfluorophenyl). Finally, DFT calculations were performed to determine the interaction between the platinum‐centered Lewis bases and the boron‐centered Lewis acids. Additionally, several possible mechanisms for the oxidative addition of the boranes BF3, BCl3, and BF2ArF to the model complex [Pt(PMe3)2] are presented. 相似文献
997.
Dr. Jürgen Bauer Prof. Dr. Holger Braunschweig Christian Hörl Dr. Krzysztof Radacki Johannes Wahler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(40):13396-13401
Chemical single‐electron reduction of 1‐mesityl‐2,3,4,5‐tetraphenylborole ( 3 ) gave a stable radical anion [CoCp*2][ 3 ] as shown in earlier investigations. Herein, we present the reaction of [CoCp*2][ 3 ] with the 2,2,6,6‐tetramethylpiperidine‐N‐oxyl radical (TEMPO), a common radical trap. Instead of radical recombination, the reaction proceeds through a redox pathway involving oxidation of the borole radical anion combined with reduction of TEMPO. This electron‐transfer process is accompanied by a deprotonation reaction of the cobaltocenium counterion by the base TEMPO? to give TEMPO‐H and a neutral cobalt(I) fulvene complex ( 7 ). The latter was not observed directly during the reaction, because it instantaneously reacts as a nucleophile attacking at the boron center of the in situ generated borole 3 to give the borate 6 . However, 7 was synthesized independently by deprotonation of [CoCp*2][PF6]. In addition, the obtained zwitterionic cobaltocenium borate 6 undergoes a photolytic rearrangement to form the borata‐alkene derivative 9 that thermally transforms to the chiral cobaltocenium borate 12 . Our investigations are based on spectroscopic evidence, X‐ray crystallography, elemental analysis, as well as DFT calculations. 相似文献
998.
Wolfgang Bauer 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):493-494
Abstract A general method to reduce arene sulfonylchlorides to diarene disulfanes has been developped using sulfur dioxide and hydroiodic acid/quarternary ammonium salts as catalysts in a two - phase system. 相似文献
999.
New ruthenium phosphinooxazoline (PHOX) complexes were synthesized and applied in the Mukaiyama aldol reaction. Four ruthenium complexes of the general formula [RuCl2(PHOX)2] were synthesized from [RuCl2(dmso)4] and the corresponding PHOX ligands through thermal ligand exchange. Two of the complexes were characterized structurally. Achiral PHOX ligands gave the ruthenium complexes as single isomers, whereas chiral PHOX ligands gave a mixture of isomers and also some incomplete substitution. After activation by chloride abstraction, one of the new ruthenium complexes was applied as catalyst in the Mukaiyama aldol reaction to give silyl-protected β-hydroxyl alcohols in 74–92% isolated yields (room temperature, 18–24 h reaction time, 1 mol % catalyst loading). 相似文献
1000.
Drishty Satpati Nadine Bauer Sven H. Hausner Julie L. Sutcliffe 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(2):765-771
Catalyst-free click reactions are effective chemical tools for synthesis of radiometal-based radiopharmaceuticals offering advantages towards preparation of non-toxic agents with high specific activity. In the present study the radiotracer [64Cu]DOTA-ADIBON3-Ala-PEG28-A20FMDV2, [64Cu]3, was synthesized for positron emission tomography imaging of integrin αvβ6 expressing tumors via a strain-promoted click reaction using both a “pre-click” and “post-click” approaches. The radiotracer, prepared in >99 % radiochemical yield, was evaluated in vitro (64.6 ± 2.8 % binding to αvβ6-positive cells vs. <5 % to αvβ6-negative cells) and in vivo (αvβ6-positive tumor uptake: 1.52 ± 0.16 % ID/g, 24 h p.i.). While the high initial renal uptake (76.2 ± 10.7 % ID/g at 1 h p.i.) was comparable to a previously reported radiotracer, [64Cu]DOTA-PEG28-A20FMDV2, [64Cu]3 showed notably improved renal clearance (11.3 ± 2.5 % ID/g at 24 h p.i.). Thus, the introduction of a chelator-strained alkyne system resulted in improved pharmacokinetics for the present radiotracer, highlighting the attractive prospects of strain-promoted click-based preparations in the construction of radiometalated bioconjugates for targeted molecular imaging and therapy. 相似文献