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991.
Grafting of polystyrene with narrowly dispersed polymer microspheres through surface-initiated atom transfer radical polymerization (ATRP) was investigated. Polydivinylbenzene (PDVB) microspheres were prepared by dispersion polymerization with poly(N-vinyl pyrrolidone) (PVP) as stabilizer. The surfaces of PDVB microspheres were chloromethylated by chloromethyl methyl ether in the presence of zinc chloride as catalyst to form chloromethylbenzene initiating core sites for subsequent ATRP grafting of styrene using CuCl/bpy as catalytic system. Polystyrene was found to be grafted not only from the particle surfaces but also from within a thin shell layer, resulting in the formation of particles size increased from 2.38-2.58μm, which can further grow to 2.93μm during secondary grafting polymerization of styrene. This demonstrates that grafting polymerization proceeds through a typical ATRP procedure with living nature. All of the prepared microspheres have narrow particle size distribution with coefficient of variation around 10%. 相似文献
992.
993.
The densities of ethanol and ethanol–water mixtures were measured with a vibrating tube densimeter at 25.0, 50.0 and 75.0 °C in the pressure range from 0.10 to 40.00 MPa. Densities were correlated using an empirical model. Partial molar volumes, excess molar volumes, isothermal compressibilities, cubic expansion coefficients and internal pressures were calculated from obtained densities. This study reports the dependence of densities, partial molar volumes, excess molar volumes, isothermal compressibilities, cubic expansion coefficients and internal pressures on composition, temperature and pressure. 相似文献
994.
Koki Tsukamoto Toshio Watanabe Umpei Nagashima Yutaka Akiyama 《Journal of Molecular Structure》2005,732(1-3):87-98
A reaction mechanism of a nitric oxide reductase, cytochrome P450nor (P450nor) from Fusarium oxysporum, was clarified by using Density functional theory and Hartree–Fock calculations. In this reaction mechanism, molecular orbital (MO) analysis revealed that the NO ligand dissociates from the heme iron immediately after one-electron reduction by NADH, and MO energy analysis revealed that NADH acts as a one-electron reducer, not as a two-electron reducer, and that NADH has a pivotal role different from other one-electron reducers. The role of NADH is to act as a double one-electron donor (i.e. one-electron transfer occurring twice) and to combine with the NO− molecule by charge recombination reaction. Our quantum chemical calculations indicated that all reactions occurring in the heme pocket are too fast to become rate-limiting. Therefore, the rate-limiting steps in the proposed reaction mechanism are the process of capturing NO and NADH into the heme pocket and the process of expelling a product generated in the heme pocket. Kinetics of these processes was discussed based on large-amplitude vibration, which helps capturing and expelling processes in a widely opened heme pocket of P450nor. The reaction mechanism proposed here well explains published experimental data. 相似文献
995.
Yuriy K. Tovbin 《Adsorption》2005,11(3-4):245-257
The equilibrium distribution and the concentration dependence of the local and average self-diffusion coefficients for pure
fluid and binary mixture components in narrow slitlike pores were analyzed. The coefficients were calculated using the lattice
gas model in the quasi-chemical approximation on the assumption of a spherical shape and approximately equal sizes of the
components. For the pure adsorbate, these calculations were compared with molecular dynamics simulations. Both methods gave
similar concentration profile changes and dynamic characteristics of interlayer particle redistributions in strong nonuniform
adsorption fields for dense fluids. A satisfactory agreement was obtained for the temperature dependences of the self-diffusion
coefficients along the pore axis. The influence of the molecule–wall potential and of intermolecular interaction were considered.
The self-diffusion coefficients of the adsorbate were shown to strongly depend on the density of the mixture and the distance
from pore walls. 相似文献
996.
Ya‐Ching Shen Yuan‐Bin Cheng Yu‐Hui Chen Ashraf Taha Khalil Chin‐Lien Ko 《中国化学会会志》2005,52(6):1263-1268
Three new clerodane diterpene derivatives were isolated from the leaves of Casearia membranacea Hance collected in Taiwan. The isolated metabolites were identified as caseamembrins P (1), Q (2), and R (3). Identification of the structures was based on detailed analysis of the spectral data, especially 2D NMR. 相似文献
997.
Luis Adrio Gemma Alberdi Adriana Amoedo Darío Lata Alberto Fernndez Javier Martínez M. Teresa Pereira Jos M. Vila 《无机化学与普通化学杂志》2005,631(11):2197-2203
Reaction of the thiosemicarbazone ligands C4H4NC(H)=NN(H)C(S)NHR (R = Me, a ; Et, b ) with Li2[PdCl4] gave the dinuclear complexes [Pd{C4H4NC(H)=NNC(S)NHR}(μ‐Cl)]2 (R = Me, 1a ; Et, 1b ) with a central Pd2Cl2 core and with deprotonation of the thiosemicarbazones at the hydrazinic nitrogen atom. Treatment of 1a and 1b with triphenylphosphine gave the mononuclear compounds [Pd{C4H4C(H)=NNC(S)NHR}(Cl)(PPh3)] (R = Me, 2a ; Et, 2b ), whereas reaction of 1a and 1b with tertiary diphosphines gave mono‐ and dinuclear compounds, as appropriate, with the corresponding diphosphine acting as a monodentate ( 6b ), chelating ( 3a ) and bridging ligand ( 4a, 5a , 4b, 5b ). Treatment of 1a and 1b with (Ph2PCH2CH2PPh2)W(CO)5 gave the new heterobimetallic complexes 7a and 7b . The crystal structures of complexes 3a and 4a are described. 相似文献
998.
通过室温固相反应合成了Ni2P2S6层状结构材料,并经XRD和Raman光谱进行了表征.与传统的高温固相反应法相比较,该法具有反应速度快、能耗低、可得均相产物的优点.TG-DTA研究表明,Ni2P2S6在空气中热氧化的终产物为Ni2P2O7,中间态可能是Ni2P2O6亚稳相. 相似文献
999.
肼基硫代甲酸酯配合物的合成、晶体结构、光谱及三阶非线性光 学性质研究 总被引:2,自引:0,他引:2
报道三种有推拉电子基团的肼基硫代酸酯衍生物配体(HL^1^~^3)。此类配体与二价过渡金属离子配位时脱去一质子,形成D-M-D和A-M-A(D=给体,M=金属,A=受体)类型、含有共轭体系的中性配合物。本文集中研究了该类配体的镍、铜、钯、铂配合物的IR、磁化率、ESR谱,电子光谱和三阶非线性光学性质,通过光谱研究初步确定了它们均为平面正方形构型配合物,文中还报道了CuL2^1的晶体结构。晶体属P1空间群,a=0.7835(2),b=1.0530(2),c=1.1816(2)nm,α=100.61(3),β=92.38(3),γ=110.00(3)ⅲ,Z=1,最终的R因子为0.063。通过晶体结构测试,进一步确定铜配合物的结构为平面构型。 相似文献
1000.