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921.
Thetrimolybdenumclusterswithgeneralformula[Mo3(μ3S)(μS)3(μdtp)(dtp)3L](dtp=(S2P(OC2H5)2)-,L=H2O,py,SC(NH2)2etc.)[1](referredtoasM1type[2]),and[Mo3(μ3S)(μS2)3(dtp)3]X(X=Cl,I)[3](referredtoasM2type),aretwomaintypesoftrimolybdenumclusterseverinvestigatedbyourresearchgroup.Aswehavealready… 相似文献
922.
钯(Ⅱ)三元配合物稳定性及其与DNA作用研究 总被引:3,自引:0,他引:3
合成了[Pd(bipy)(DL-gly)]Cl•2H22O(2)两个钯三元配合物. 配合物1和2的稳定常数对数值lgβ分别为13.81和13.71, 表征常数ΔlgK、lgX高于统计值, 表明在配合物分子内存在d-p π电子协同效应. 紫外光谱、荧光光谱结果表明, 配合物1和2与鱼精DNA主要以插入方式键合, 键合常数分别为2.37×106(1)和4.57×106(2). CD光谱图也显示, 配合物与DNA分子之间发生了作用. 质粒pBR322 DNA的凝胶电泳图表明, 配合物浓度在3.00×10-3~7.50×10-4 mol •L-1范围内对DNA分子有切割作用, 配合物浓度低于3.75×10-4 mol •L-1时则主要以插入方式与DNA键合. 相似文献
923.
Grignard reagents cleave the oxirane ring of 2,7-epoxydiisophoran-1-ol producing diisophor-7-ene-1,2-diol, the formulation of which is in accord with its13C-nmr spectrum, and its further reactions. It yields a 1,2-cyclic sulphite ester, a 7,8-epoxide, and is converted into 1-acetoxydiisophora-2,7-diene by acetic anhydride, and into diisophor-2(7)-en-1-ol by successive dehydration and hydrogenation. Its allylic hydroxylation by selenium dioxide is attended by dehydration, producing moderate yields of diisophora-2,7-diene-1,6-diol.
Diisophoron und verwandte Verbindungen. 15. Mitt. 2,7-Epoxydiisophorane: Oxiranspaltung mittelsGrignard-Verbindungen
Zusammenfassung 2,7-Epoxydiisophoran-1-ol wird vonGrignard-Verbindungen unter Spaltung des Oxiranringes in Diisophor-7-en-1,2-diol umgewandelt, dessen Struktur durch sein13C-Kernresonanz-Spektrum und seine weiteren Umsetzungen bewiesen wird: Es bildet einen cyklischen 1,2-Sulphit-Ester, ein 7,8-Epoxyd, und wird von Essigsäureanhydrid in 1-Acetoxydiisophora-2,7-dien sowie durch aufeinanderfolgende Wasserabspaltung und katalytische Hydrierung in Diisophor-2(7)-en-1-ol umgewandelt. Hydroxylierung in Allyl-Stellung durch Selendioxyd ergibt unter gleichzeitiger Wasserabspaltung geringe Ausbeuten von Diisophora-2,7-dien-1,6-diol.相似文献
924.
Anton Betten Adalbert Kerber Reinhard Laue Alfred Wassermann 《Designs, Codes and Cryptography》1998,15(1):5-27
We show the existence of simple 8-(31,10,93) and 8-(31,10,100) designs. For each value of we show 3 designs in full detail. The designs are constructed with a prescribed group of automorphisms PSL(3,5) using the method of Kramer and Mesner KramerMesner76. They are the first 8-designs with small parameters which are known explicitly. We do not yet know if PSL(3,5) is the full group of automorphisms of the given designs. There are altogether 138 designs with = 93 and 1658 designs with = 100 and PSL(3,5) as a group of automorphisms. We prove that they are all pairwise non-isomorphic. For this purpose, a brief account on the intersection numbers of these designs is given. The proof is done in two different ways. At first, a quite general group theoretic observation shows that there are no isomorphisms. In a second approach we use the block intersection types as invariants, they classify the designs completely. 相似文献
925.
We study the existence and structure of extremals for one-dimensional variational problems on a torus and the properties of the minimal average action as a function of the rotation number. We show that, for a generic integrand f, the minimum of the minimal average action is attained at a rational point mn
–1 where n1 and m are integers; also, for each initial value, there exists an (f)-weakly optimal solution over an infinite horizon. 相似文献
926.
We study cohomogeneity one Riemannian manifolds and we establish some simple criterium to test when a singular orbit is totally geodesic. As an application, we classify compact, positively curved Riemannian manifolds which are acted on isometrically by a non-semisimple Lie group with an hypersurface orbit. 相似文献
927.
Marja Kankaanrinta 《Geometriae Dedicata》2008,136(1):167-173
In this paper we prove an equivariant version of the uniformization theorem for closed subanalytic sets: Let G be a Lie group and let M be a proper real analytic G-manifold. Let X be a closed subanalytic G-invariant subset of M. We show that there exist a proper real analytic G-manifold N of the same dimension as X and a proper real analytic G-equivariant map such that .
相似文献
928.
We study the nontrivial Killing vector fields of constant length and the corresponding flows on smooth Riemannian manifolds. We describe the properties of the set of all points of finite (infinite) period for general isometric flows on Riemannian manifolds. It is shown that this flow is generated by an effective almost free isometric action of the group S 1 if there are no points of infinite or zero period. In the last case, the set of periods is at most countable and generates naturally an invariant stratification with closed totally geodesic strata; the union of all regular orbits is an open connected dense subset of full measure. 相似文献
929.
In this paper we prove some properties of the nonabelian cohomology of a group with coefficients in a connected Lie group . When is finite, we show that for every -submodule of which is a maximal compact subgroup of , the canonical map is bijective. In this case we also show that is always finite. When and is compact, we show that for every maximal torus of the identity component of the group of invariants , is surjective if and only if the -action on is -semisimple, which is also equivalent to the fact that all fibers of are finite. When , we show that is always surjective, where is a maximal compact torus of the identity component of . When is cyclic, we also interpret some properties of in terms of twisted conjugate actions of .
930.
Jeppe Langeland Natascha W. Persen Elisabeth Gruber Hjalte V. Kiefer Adil M. Kabylda Anastasia V. Bochenkova Lars H. Andersen 《Chemphyschem》2021,22(9):833-841
Green Fluorescent Protein (GFP) is known to undergo excited-state proton transfer (ESPT). Formation of a short H-bond favors ultrafast ESPT in GFP-like proteins, such as the GFP S65T/H148D mutant, but the detailed mechanism and its quantum nature remain to be resolved. Here we study in vacuo, light-induced proton transfer from the GFP chromophore in hydrogen-bonded complexes with two anionic proton acceptors, I− and deprotonated trichloroacetic acid (TCA−). We address the role of the strong H-bond and the quantum mechanical proton-density distribution in the excited state, which determines the proton-transfer probability. Our study shows that chemical modifications to the molecular network drastically change the proton-transfer probability and it can become strongly wavelength dependent. The proton-transfer branching ratio is found to be 60 % for the TCA complex and 10 % for the iodide complex, being highly dependent on the photon energy in the latter case. Using high-level ab initio calculations, we show that light-induced proton transfer takes place in S1, revealing intrinsic photoacid properties of the isolated GFP chromophore in strongly bound H-bonded complexes. ESPT is found to be very sensitive to the topography of the highly anharmonic potential in S1, depending on the quantum-density distribution upon vibrational excitation. We also show that the S1 potential-energy surface, and hence excited-state proton transfer, can be controlled by altering the chromophore microenvironment. 相似文献