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131.
Dr. Sabine Lennarz MSc Therese Christine Alich Dr. Tony Kelly Dr. Michael Blind Prof. Dr. Heinz Beck Prof. Dr. Günter Mayer 《Angewandte Chemie (International ed. in English)》2015,54(18):5369-5373
Cellular behavior is orchestrated by the complex interactions of a myriad of intracellular signal transduction pathways. To understand and investigate the role of individual components in such signaling networks, the availability of specific inhibitors is of paramount importance. We report the generation and validation of a novel variant of an RNA aptamer that selectively inhibits the mitogen‐activated kinase pathway in neurons. We demonstrate that the aptamer retains function under intracellular conditions and that application of the aptamer through the patch‐clamp pipette efficiently inhibits mitogen‐activated kinase‐dependent synaptic plasticity. This approach introduces synthetic aptamers as generic tools, readily applicable to inhibit different components of intraneuronal signaling networks with utmost specificity. 相似文献
132.
Encapsulation of Functional Organic Compounds in Nanoglass for Optically Anisotropic Coatings
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Matthias Stöter Dr. Bernhard Biersack Dr. Sabine Rosenfeldt Markus J. Leitl Dr. Hussein Kalo Prof. Dr. Rainer Schobert Prof. Dr. Hartmut Yersin Prof. Geoffrey A. Ozin Prof. Dr. Stephan Förster Prof. Dr. Josef Breu 《Angewandte Chemie (International ed. in English)》2015,54(16):4963-4967
A novel approach is presented for the encapsulation of organic functional molecules between two sheets of 1 nm thin silicate layers, which like glass are transparent and chemically stable. An ordered heterostructure with organic interlayers strictly alternating with osmotically swelling sodium interlayers can be spontaneously delaminated into double stacks with the organic interlayers sandwiched between two silicate layers. The double stacks show high aspect ratios of >1000 (typical lateral extension 5000 nm, thickness 4.5 nm). This newly developed technique can be used to mask hydrophobic functional molecules and render them completely dispersible in water. The combination of the structural anisotropy of the silicate layers and a preferred orientation of molecules confined in the interlayer space allows polymer nanocomposite films to be cast with a well‐defined orientation of the encapsulated molecules, thus rendering the optical properties of the nanocoatings anisotropic. 相似文献
133.
134.
Anke Schwarzer Sabine Fels Uwe Bhme 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(6):511-516
Dimethyl[N‐(4‐oxidopent‐3‐en‐2‐ylidene)valinato‐κ3O,N,O′]silicon(IV), C12H21NO3Si, (II), crystallizes in the orthorhombic space group P212121. The chiral compound undergoes two sharp enantiotropic phase transitions upon cooling. The first transformation occurs at 163 K to yield a unit cell with one axis having double length. This intermediate‐temperature form has the monoclinic space group P21. The second transition takes place at 142 K and converts the single crystal into the low‐temperature form in the orthorhombic space group P212121. This transition proceeds under tripling of the a axis of the high‐temperature form. Both phase transitions are fully reversible and correspond to order–disorder transitions of the isopropyl group of the valine unit in the ligand backbone. The phase transitions presented here raise questions, since they do not fit into the rules of group–subgroup relationships. 相似文献
135.
Dominik Grtner Andr Luiz Stein Sabine Grupe Johannes Arp Axel JacobivonWangelin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(36):10691-10695
Stable C O linkages are generally unreactive in cross‐coupling reactions which mostly employ more electrophilic halides or activated esters (triflates, tosylates). Acetates are cheap and easily accessible electrophiles but have not been used in cross‐couplings because the strong C O bond and high propensity to engage in unwanted acetylation and deprotonation. Reported herein is a selective iron‐catalyzed cross‐coupling of diverse alkenyl acetates, and it operates under mild reaction conditions (0 °C, 2 h) with a ligand‐free catalyst (1–2 mol %). 相似文献
136.
Silke C. Wenzel Holger Hoffmann Jidong Zhang Laurent Debussche Sabine Haag‐Richter Michael Kurz Frederico Nardi Peer Lukat Irene Kochems Heiko Tietgen Dietmar Schummer Jean‐Paul Nicolas Loreley Calvet Valerie Czepczor Patricia Vrignaud Agnes Mühlenweg Stefan Pelzer Rolf Müller Mark Brnstrup 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(51):15781-15785
137.
Synthesis of Cembranoid Analogues through Ring‐Closing Metathesis of Terpenoid Precursors: A Challenge Regarding Ring‐Size Selectivity
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Tanja Heidt Dr. Angelika Baro Prof. Andreas Köhn Prof. Sabine Laschat 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(35):12396-12404
A systematic study on ring‐closing metathesis with Grubbs II catalyst to cembranoid macrocycles is described. Acyclic terpenoids with a functional group X in the homoallylic position relative to an RCM active terminus and substituents R, R1 directly attached to the other terminal double bond were prepared from geraniol derived trienes and fragments that are based on bromoalkenes and dimethyl malonate. Such terpenoids were suitable precursors, despite the presence of competing double bonds in their framework. The size of R and R1 is crucial for successful macrocyclization. Whereas small alkyl substituents at the double bond directed the RCM towards six‐membered ring formation, cross metathesis leading to dimers dominated for bulkier alkyl groups. A similar result was obtained for precursors without functional group X. In the case of unsymmetrically substituted terpenoid precursor (R=Et, R1=Me) with homoallylic OTBS or OMe group, the RCM could be controlled towards formation of macrocyclic cembranoids, which were isolated with excellent E‐selectivity. The role of the substituents was further studied by quantum chemical calculations of simplified model substrates. Based on these results a mechanistic rationale is proposed. 相似文献
138.
We study spectral approximations of Schrödinger operators T = ?Δ+Q with complex potentials on Ω = ?d, or exterior domains Ω??d, by domain truncation. Our weak assumptions cover wide classes of potentials Q for which T has discrete spectrum, of approximating domains Ωn, and of boundary conditions on ?Ωn such as mixed Dirichlet/Robin type. In particular, Re Q need not be bounded from below and Q may be singular. We prove generalized norm resolvent convergence and spectral exactness, i.e. approximation of all eigenvalues of T by those of the truncated operators Tn without spectral pollution. Moreover, we estimate the eigenvalue convergence rate and prove convergence of pseudospectra. Numerical computations for several examples, such as complex harmonic and cubic oscillators for d = 1,2,3, illustrate our results. 相似文献
139.
Sabine Martin-Seigle Marie-Claude Pélissier Paul J.T. Filippi 《Flow, Turbulence and Combustion》1998,61(1-4):71-83
This paper deals with acoustic radiation by a thin elastic shell, closed by two perfectly rigid discs, immersed in water and
filled with air. The system is driven by an internal acoustic source. The shell has a length L, is clamped along one of its
boundaries and is freely supported along the other boundary.
Using the infinite domain Green's function, the radiated acoustic pressure is modeled by a hybrid layer potential (linear
combination with nonreal coefficient of a simple layer and a double layer). Using Green's tensor of the in vacuo shell operator,
the shell displacement is expressed as the sum of the field generated by the acoustic pressures and that due to boundary sources.
Finally, the Green's function of the interior Neumann problem is used to express the acoustic pressure inside the shell in
terms of the acoustic source and shell normal displacement: this representation fails for any frequency equal to one of the
resonance frequencies of the shell interior.
To overcome this, a light fluid approximation, which is allowed because the inner fluid is a gas, is adopted. Around each
resonance frequency, an inner approximation is defined which matches the classical outer approximation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
140.
Anika Sabine Lindner Egor Geist Mimoza Gjikaj Andreas Schmidt 《Journal of heterocyclic chemistry》2014,51(2):423-431
Pyrrolo[2,1‐c][1,4]benzodiazepine‐5,11‐dione and its 7‐bromo derivative were alkylated at the N10 atom applying various methods. The resulting products were subjected to Suzuki–Miyaura reactions using a catalyst system consisting of Pd(Cl)2(PPh3)2 and sodium tert‐butanolate in toluene. Results of an X‐ray single crystal analysis are presented. 相似文献