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961.
LI Ling WEI Yong-de LIU Ji-hong YANG Lu-qing ZHANG Gui-ling 《高等学校化学研究》2006,22(4):510-514
IntroductionPi(π) conjugated polymers have received exten-sive experimental and theoretical attention because oftheir fascinating electronic and optical properties[1—3].Recently, many new experiment results[4—6]have re-vealed that the inter-chain inter… 相似文献
962.
Fifteen isomers of [Si,N,C,O]2+ system are obtained at UB3LYP/6-311G(d) and UCCSD(T)/6-311+G(2df) (single-point) levels. The analyses are made for predicting the structures of optimized isomers, while ionic fragments with lower energies are suggested. The calculatedresults indicate that linear isomer SiNCO2+(2П) is thermodynamically the most stable species in [Si,N,C,O]2+ system, followed by linear SiOCN2+ (2П), SiCNO2+ (2П), and SiC(NO) (2A") with NCO three-membered ring. The order of stability of several kinetically stable isomers is SiNCO2 >SiCNO2+ (2П)>SiOCN2+ >SiC(NO)2+>OSiNC2+ (2П). The obtained results by analyzing the isomerizations and ionic fragment patterns show that the signal peaks of [Si,N,C,O]2+ are attributed to the contribution of linear SiNCO2+ species, which is metastable and can dissociate to the ionic fragments in the mass spectrometry experiments. 相似文献
963.
Yu?Haitao Chi?Yujuan Fu?HonggangEmail author Huang?Xuri Li?Zesheng Sun?Jiazhong 《中国科学B辑(英文版)》2002,45(1):1-7
The potential energy surface of HPO2 system including eight isomers and twelve transition states is predicated at MP2/6-311++G(d, p) and QCISD(t)/6-311++G(3df,2p)(single-point)
levels of theory. On the potential energy surface, cis-HOPO(E1) is found to be thermodynamically and kinetically most stable isomer followed by trans-HOPO(E2) and HPO(O)(C2v, E3) at 10.99 and 48.36 kJ/mol higher, respectively. Based on the potential energy surface, only E1 and E3 are thermodynamically
stable isomers, and should be experimentally observable. The products cis-HPOO(E5) and trans-HPOO(E6) in the first-step reaction of HP with O2 can isomerize into isomer E1 that has higher stability. The reaction of OH with PO will directly lead to the formation of
isomer E1. The computed results are well consistent with the previous experimental studies. 相似文献
964.
直接甲醇燃料电池电催化剂载体碳纳米带的合成与表征 总被引:2,自引:0,他引:2
以间苯二酚和甲醛为碳前体,合成了一种新型碳纳米材料碳纳米带(CNRs), 并采用透射电镜(TEM)、 X射线衍射(XRD)及氮气吸附/脱附测试对CNRs进行了结构表征. 结果表明,所合成的CNRs具有很高的石墨化程度及较规则的带状结构,带宽约为8~20 nm, BET比表面积为283 m2/g, 氮气等温线为type-Ⅳ型,表明CNRs为中孔结构,平均孔径约为8.2 nm. 以CNRs为载体通过多元醇法制备了45%PtRu/CNRs电催化剂,该催化剂与以Vulcan XC-72R为载体的PtRu电催化剂相比,直接甲醇燃料电池单池性能得到明显提高. 相似文献
965.
The estimation of correlation dimension of continuous and discreet deterministic chaotic processes corrupted by an additive noise and outliers observations is investigated. In this paper we propose a new estimator of correlation dimension based on similarity between the evolution of Gaussian kernel correlation sum (Gkcs) and that of modified Boltzmann sigmoidal function (mBsf), this estimator is given by the maximum value of the first derivative of logarithmic transform of Gkcs against logarithmic transform of bandwidth, so the proposed estimator is independent of the choice of regression region like other regression estimators of correlation dimension. Simulation study indicates the robustness of proposed estimator to the presence of different types of noise such us independent Gaussian noise, non independent Gaussian noise and uniform noise for high noise level, moreover, this estimator is also robust to presence of 60% of outliers observations. Application of this new estimator with determination of their confidence interval using the moving block bootstrap method to adjusted closed price of S&P500 index daily time series revels the stochastic behavior of such financial time series. 相似文献
966.
In this paper, we investigate some sufficient conditions for the breakdown of local smooth solutions to the three dimensional nonlinear nonlocal dissipative system modeling electro-hydrodynamics. This model is a strongly coupled system by the well-known incompressible Navier–Stokes equations and the classical Poisson–Nernst–Planck equations. We show that the maximum of the vorticity field alone controls the breakdown of smooth solutions, which reveals that the velocity field plays a more dominant role than the density functions of charged particles in the blow-up theory of the system. Moreover, some Prodi–Serrin type blow-up criteria are also established. 相似文献
967.
Ying Li Siwei Xu Dr. Xianfa Zhang Yi Man Dr. Jing Zhang Guangming Zhang Dr. Shuo Chen Dr. Chunbo Duan Dr. Chunmiao Han Prof. Hui Xu 《Angewandte Chemie (International ed. in English)》2023,62(39):e202308410
Electroluminescent (EL) clusters emerged rapidly, owing to their organic–inorganic hybrid character useful for comprehensive performance integration and the potential for large-scale display and lighting applications. However, despite their good photoluminescent (PL) properties, until present, no efficient EL monodentate ligand-based clusters were reported due to structural variation during processing and excitation and exciton confinement on cluster-centered quenching states. Here we demonstrate an effective bulky passivation strategy for efficient cluster light-emitting diodes with a monophosphine Cu4I4 cube named [TMeOPP]4Cu4I4. With terminal pyridine groups, an active matrix named TmPyPB supports an effective host-cluster interplay for configuration fixation, structural stabilization, and exciton-confinement optimization. Compared to common inactive hosts, the passivation effects of TmPyPB markedly reduce trap-state densities by 24–40 % to suppress nonradiative decay, resulting in state-of-the-art PL and EL quantum yields reaching 99 % and 15.6 %, respectively, which are significantly improved by about 7-fold. TmPyPB simultaneously increases EL luminance to 104 nits, which is ≈100-fold that of the non-doped analogue. 相似文献
968.
Hui Zhang Gui-ling Zhang Jing-yao Liu Miao Sun Bo Liu Ze-sheng Li 《Theoretical chemistry accounts》2008,119(5-6):445-451
Theoretical investigations are carried out on the reaction multi-channel CH3COCH3 + Cl (R1) and CH3 COCH3 + CH3 (R2) by means of direct dynamics methods. The minimum energy path (MEP) is obtained at the MP2/6-31 + G(d,p) level, and energetic
information is further refined at the BMC–CCSD (single-point) level. The rate constants are calculated by the improved canonical
variational transition state theory (ICVT) with the small-curvature tunneling (SCT) correction in a wide temperature range
200–3,000 K. The theoretical overall rate constants are in good agreement with the available experimental data and are found
to be k
1 = 3.08 × 10−17
T
2.03exp(−32.96/T) and k
2 = 1.61 × 10−23
T
3.53 exp(−3969.51/T) cm3molecule−1s−1.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
969.
Gui-Ling Zhang Hui Zhang Dong-Ping Li Dan Chen Xiao-Yang Yu Bo Liu Ze-Sheng Li 《Theoretical chemistry accounts》2008,121(3-4):109-122
The end-substitution effects on the geometric and electronic structures of oligoheterocyclics are systematically studied using the density functional theory. It is found that the influence of the end-substitution does not depend on the heteroatom. End-substitution plays a fine-tune effect on the geometry and the excitation state. While the influences on the conducting type (p-type or n-type) and the inter-chain charge carrier hoping channels are much different between the electron-donating –CH 3 and electron–accepting –CN substitutions. Both molecular electrostatic potentials and charge carrier injection rates indicate that the –CH 3/–CH 3 substitution is beneficial to the p-type doping, while the –CN/–CN substitution is in favor of the n-type doping, which is in agreement with the experimental observations. The –CH 3 substituted packing dimers exert similar intermolecular interactions to the unsubstituted ones. The –CN substituted packing dimers yield much stronger intermolecular interactions comparing to the –CH 3 substituted ones. It could be anticipated that the –CN substitution would be helpful to the charge carrier hopings between chains and thereby enhance the conductivity. 相似文献
970.
Zexu Fang Ying Gu Xinran Dong Gen Zhang Lin Li Xiaoguang Zhou Chungui Tian 《中国化学快报》2023,34(9):108128-334
Hydrogenation reactions play crucial roles on chemical synthesis and pollutant elimination. The improvement of the ability to activate reactants and increase of the contact probability between the catalysts and reactants are positive to improve the catalytic performance. Herein, we have reported the design of two-dimensional porous Ni-Ni3N-Ni Mo N heterojunction sheets(2D Mo-Ni based nanosheets) for efficient catalytic hydrogenation of the aromatic nitro-compounds. The heterojunction ... 相似文献