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31.
32.
Concise construction of novel bridged bicyclic lactams by sequenced Ugi/RCM/Heck reactions 总被引:1,自引:0,他引:1
Ribelin TP Judd AS Akritopoulou-Zanze I Henry RF Cross JL Whittern DN Djuric SW 《Organic letters》2007,9(24):5119-5122
Herein we report a concise protocol for the diastereoselective synthesis of novel bridged bicyclic lactams from commercially available components by the sequence of Ugi, ring-closing metathesis (RCM), and Heck reactions. X-ray diffraction studies revealed that the bicyclic products contain varying degrees of pyramidalization of the bridgehead nitrogen atom. 相似文献
33.
Christopher J. Burns Robert D. Groneberg Joseph M. Salvino Gerard McGeehan Stephen M. Condon Robert Morris Matthew Morrissette Rose Mathew Shelley Darnbrough Kent Neuenschwander Anthony Scotese Stevan W. Djuric John Ullrich Richard Labaudiniere 《Angewandte Chemie (International ed. in English)》1998,37(20):2848-2850
One common synthetic route creates small-molecule libraries directed toward two functionally distinct target families. The novel structural template 1 can independently display the necessary pharmacophore patterns for inhibition of members of two different biomolecular target families, the matrix metalloproteinases (MMPs) or the phosphodiesterases (PDEs). The incorporation of multiple target family directed design elements into combinatorial library design could help expedite the pharmaceutical lead discovery process. Z=OR′ (PDE4), H (MMPs). 相似文献
34.
Wai Chou Wan Yongli Gao Thomas E. Goodwin Stevan A. Gonzalez William A. Feld Bing R. Hsieh 《Macromolecular Symposia》1998,125(1):205-211
The synthesis of several highly phenylated PPV derivatives by a chlorine precursor route (CPR) was investigated in order to understand its scope. Three 1,4-bis(chloromethyl)benzene monomers were prepared via a robust and versatile synthetic procedure involving the Diels-Alder reaction. The monomers were then polymerized to the corresponding precursor polymers with about 1.0 equivalent of potassium t-butoxide in THF. Only one monomer gave a soluble precursor polymer while the other two gave insoluble precursor polymers. The soluble precursor polymer was deposited as thin films and then converted to the corresponding PPV derivative, which showed green photoluminesence and electroluminesence. 相似文献
35.
Karoline Johansson Stevan Pilipović Nenad Teofanov Joachim Toft 《Monatshefte für Mathematik》2012,166(2):181-199
We introduce admissible lattices and Gabor pairs to define discrete versions of wave-front sets with respect to Fourier–Lebesgue and modulation spaces. We prove that these wave-front sets agree with each other and with corresponding wave-front sets of “continuous type”. This implies that the coefficients of a Gabor frame expansion of f are parameter dependent, and describe the wave-front set of f. 相似文献
36.
Ramasesha K De Marco L Horning AD Mandal A Tokmakoff A 《The Journal of chemical physics》2012,136(13):134507
We present an approach for calculating nonlinear spectroscopic observables, which overcomes the approximations inherent to current phenomenological models without requiring the computational cost of performing molecular dynamics simulations. The trajectory mapping method uses the semi-classical approximation to linear and nonlinear response functions, and calculates spectra from trajectories of the system's transition frequencies and transition dipole moments. It rests on identifying dynamical variables important to the problem, treating the dynamics of these variables stochastically, and then generating correlated trajectories of spectroscopic quantities by mapping from the dynamical variables. This approach allows one to describe non-Gaussian dynamics, correlated dynamics between variables of the system, and nonlinear relationships between spectroscopic variables of the system and the bath such as non-Condon effects. We illustrate the approach by applying it to three examples that are often not adequately treated by existing analytical models--the non-Condon effect in the nonlinear infrared spectra of water, non-Gaussian dynamics inherent to strongly hydrogen bonded systems, and chemical exchange processes in barrier crossing reactions. The methods described are generally applicable to nonlinear spectroscopy throughout the optical, infrared and terahertz regions. 相似文献
37.
An intramolecular Heck coupling of the product of an aza Baylis-Hillman reaction to afford conformationally constrained scaffolds is reported. 相似文献
38.
Marco Vincenti Stevan R. Horning R. Graham Cooks 《Journal of mass spectrometry : JMS》1988,23(8):585-593
Ionized limonene and related isomeric compounds have been examined by collisional activation at both gaseous and solid targets. The gas-phase collision-induced dissociation (CID) experiments were performed as a function of collision energy and scattering angle and the surface-induced dissociation (SID) experiments as a function of collision energy, in order to vary systematically the internal energy deposited in the molecular ion. The virtual absence of retro-Diels–Alder (RDA) fragmentation upon conventional CID, as compared to its importance in the electron impact (EI) mass spectrum, the subject of a study by Boyd and coworkers, was confirmed. However, as the ion internal energy was increased by raising the collision energy or the scattering angle, RDA fragmentation was observed and it became a dominant mode of fragmentation for SID at collision energies in the range of 25–50 eV. The energy deposited into the colliding ion in the SID technique is compared with that deposited upon CID in the eV and keV energy ranges and upon EI. The order obtained is: SID > EI > low-energy, multiple-collision CID > high-energy, single-collision CID > low-energy, single-collision CID. The distribution of energies in SID is narrower than in the other techniques. High internal energies are accessible by increasing the scattering angle in CID; however, this is accompanied by an increase in the width of the internal energy distribution, and it is therefore not possible to channel fragmentation predominantly into RDA by this method. It is concluded that RDA fragmentation of limonene is a high-energy process and that this is the explanation for its behavior. Isomerization, occurring through 1,3-hydrogen migrations of the molecular ions of limonene, isolimonene, terpinolene and α-terpinene, was investigated and long-lived molecular ions of the first three compounds were found to maintain distinct structures. 相似文献
39.
We analyze family of solutions to multidimensional scalar conservation law, with flux depending on the time and space explicitly,
regularized with vanishing diffusion and dispersion terms. Under a condition on the balance between diffusion and dispersion
parameters, we prove that the family of solutions is precompact in L1loc{L^1_{\rm loc}}. Our proof is based on the methodology developed in Sazhenkov (Sibirsk Math Zh 47(2):431–454, 2006), which is in turn based
on Panov’s extension (Panov and Yu in Mat Sb 185(2):87–106, 1994) of Tartar’s H-measures (Tartar in Proc R Soc Edinb Sect A 115(3–4):193–230, 1990), or Gerard’s micro-local defect measures (Gerard Commun
Partial Differ Equ 16(11):1761–1794, 1991). This is new approach for the diffusion–dispersion limit problems. Previous results
were restricted to scalar conservation laws with flux depending only on the state variable. 相似文献
40.
Irini Akritopoulou-Zanze Alan Whitehead Jan E. Waters Rodger F. Henry Stevan W. Djuric 《Tetrahedron letters》2007,48(20):3549-3552
We report the synthesis of highly functionalized 3,4-dihydroquinolin-2(1H)-ones via sequential Ugi/acrylanilide photocyclization reactions. The [6π]-photocyclization proceeds in excellent yields and with preferential trans-selectivity for the newly formed ring system. 相似文献