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41.
设计合成了一个新型吡啶基二氮环配体L(N,N'-双(吡啶基-3-亚甲基)-1,5-二氮环辛烷)及其铜配位聚合物{[Cu(滋-H2L)(L)Cl](ClO4)3}∞(1),研究了此配合物的晶体结构、光谱及磁性质。该配合物属正交晶系,Pnma空间群,晶胞参数为a=3.5170(17)nm,b=1.0440(5)nm,c=1.1966(6)nm,V=4.394(4)nm3,Z=4。配体L以顺式螯合和反式桥联两种不同的配位形式将铜离子连接起来形成一维链状阳离子结构。 相似文献
42.
C. C. Camarasu 《Chromatographia》2002,56(1):S131-S135
Summary A sensitive headspace SPME method for the extraction of residual solvents from pharmaceutical products has been developed
and optimized. It was found that minimizing sample and headspace volume has a beneficial effect on extraction efficiency.
At the same time the method reproducibility was seriously affected by reducing sample and headspace volume. The added air
volume was not found to have any significant influence on method sensitivity. The method showed reproducibilities of less
than 10% and detection limits as low as 1 ppb for benzene and dichloromethane. The headspace SPME method is around 1000 times
more sensitive than static headspace. The optimized parameters were headspace volume 1.5 mL, sample volume 10 μL, and extraction
time 30 min. The method was successfully applied to the identification of unknown residual solvents in three different proprietary
active drug substances and was successfully applied to the confirmation of the presence of benzene in a proprietary drug substance.
Presented at Balaton Symposium '01 on High-Performance Separation Methods, Siófok, Hungary, September 2–4, 2001 相似文献
43.
Yan-Tuan Li Zong-Hui Jiang Dai-Zeng Liao Shi-Ping Yan Shu-Lin Ma Gen-Lin Wang 《中国化学》1994,12(5):414-418
Six novel μ-oxamido binuclear complexes, namely Cu(axpn)Ln(L)2(ClO4)3 (Ln: Eu, Gd, Tb, Nd, Ho, Er), where oxpn is N,N'-bis(3-aminopropyl) oxamido, L denotes 5-nitro,10-phenanthroline (abbreviated as NO2-phen), have been synthesized and characterised. The magnetic susceptibility of complexes Cu(oxpn)Gd(NO2-phen)2(ClO4)3.2H2O was measured over the 4–300 K and the observed data were successfully simulated by equation based on spin Hamiltonian operator (H = -2J1 · S2), giving the exchange integral J(Cu-Gd)=-1.62 cm?1. This indicates a weak antiferromagnetic interaction between the Cu(II) and Gd(III) ions. 相似文献
44.
O. LeynaudA. Lafond Y. MoëloP. Palvadeau A. Meerschaut 《Journal of solid state chemistry》2002,168(1):41-51
Crystal structures of two new misfit compounds, [SrGd0.5S1.5]1.16NbS2 and [Sr(Fe,Nb)0.5S1.5]1.13NbS2, were determined through the composite approach, i.e., by refining each subpart (Q, H-parts, and the common part) of these composite materials, separately. The Q-part is a three-atom-thick layer, with the NaCl-type structure, where external SrS planes enclose the inner GdS or (Fe,Nb)S plane; the structural difference between these two compounds lies in the central layer within the Q-part: Gd and S atoms are in special positions (octahedral coordination), while Fe and S atoms are statistically distributed on split (×4) positions (tetrahedral coordination) around a central unique site (=special position occupied by Nb). The H-part is a sandwich of sulfur planes enclosing the inner Nb plane as observed for the structure of the binary compound NbS2 itself. The Sr-Gd derivative shows a paramagnetic behavior in the whole studied temperature range (2-300 K). On the other hand, antiferromagnetic interactions occur in the Sr-Fe derivative; the complex magnetic behavior of this compound is related to the statistical distribution of Fe atoms which leads to frustration of the magnetic interactions. At room temperature, experimental values obtained from Mössbauer spectrum correspond to Fe3+ in tetrahedral sulfur environment: isomer shift δ=0.32 mm s−1, and quadrupole splitting ΔE=0.48 mm s−1. 相似文献
45.
46.
Liya?Wang Zhiliang?Liu Chenxi?Zhang Zhanquan?Liu Daizheng?Liao Zonghui?JiangEmail author Shiping?Yan 《中国科学B辑(英文版)》2003,46(6):533-541
A novel one-dimensional manganese(II) complex containing nitronyl nitroxide radical [Mn2(IM2-py)2(Ac)2(μ1,1-N3)(μ1,3-N3) · EtOH]
n
was synthesized and characterized structurally and magnetically. It crystallizes in the monoclinic space group p21/n. Each Mn(II) ion is six-coordinated in a distorted octahedral environment. The two N atoms of the nitronyl nitroxide radical
and the two O atoms of acetate ligands are in the equatorial plane, whereas the two different azido bridging ligands are in
trans axial position. Mn(II) ions are linked by nitrogen atom of μ1,1-azido and oxygen atoms of two carboxy groups to form a Mn-Mn unit. Mn-Mn units are linked by azido ligands through μ1,3 bridging style to form a one-dimensional chain. The compound is connected by the coordination bonds, π-π interactions and
hydrogen bonds as a three-dimensional structure. Magnetic susceptibility data support that there are stronger antiferromagnetic
interactions between the radical and Mn(II) ion, weak antiferromagnetic interactions between the Mn-R units, and very weak
antiferromagnetic interactions between the R-Mn-Mn-R units. 相似文献
47.
以N,N-二甲基甲酰胺(DMF)为溶剂,丁酮为内标,采用PV-101毛细管色谱柱 (30 m×0.22 mm),氢火焰离子化检测器,建立兰索拉唑中五种有机溶剂甲醇、乙醇、丙酮、二氯甲烷、乙酸乙酯残留量的定量分析方法。五种有机溶剂检出限分别为0.002 4%,0.002 4%, 0.001 2%,0.000 6%,0.000 6%;在10-1000 mg·L-1浓度范围内,各组分线性关系良好;对应的平均回收率分别为100.8%±3.6%,102.1%±2.3%,99.97%±4.1%,99.63%±2.7%, 102.3%±3.5%。 相似文献
48.
A series of dilute liquid crystalline solvents are used to study the effect of slight anisotropy caused by partial alignment on chemical shift and residual dipolar coupling (RDC) in small molecules. The residual dipolar couplings between protons in solutes are found to be almost independent of the local environment. It is also found that the chemical shift does not change over the concentration range observed. A linear relationship between residual dipolar coupling and liquid crystal concentration is observed at relatively low concentrations, but is severely violated at high concentrations. 相似文献
49.
Density functional theory, in combination with a) a careful choice of the exchange-correlation part of the total energy and b) localized basis sets for the electronic orbitals, has become the method of choice for calculating the exchange-couplings
in magnetic molecular complexes. Orbital expansion on plane waves can be seen as an alternative basis set especially suited
to allow optimization of newly synthesized materials of unknown geometries. However, little is known on the predictive power
of this scheme to yield quantitative values for exchange coupling constants J as small as a few hundredths of eV (50–300 cm−1). We have used density functional theory and a plane waves basis set to calculate the exchange couplings J of three homodinuclear Cu-based molecular complexes with experimental values ranging from +40 cm−1 to −300 cm−1. The plane waves basis set proves as accurate as the localized basis set, thereby suggesting that this approach can be reliably
employed to predict and rationalize the magnetic properties of molecular-based materials.
Corresponding author. E-mail: Carlo.Massobrio@ipcms.u-strasbg.fr
Received August 5, 2002; accepted August 9, 2002 相似文献
50.
Tapan Kumar Lal John F. Richardson Mark S. Mashuta Robert M. Buchanan Rabindranath Mukherjee 《Polyhedron》1997,16(24):1248-4336
Synthesis and characterization of a nitrite-bound copper(II) compound [CuL4)2(ONO)]ClO4 have been achieved (L4 = 2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine]. The bidentate ligand L4 provides a pyridine and a pyrazole donor site; however, they are separated by a methylene spacer. The complex has been structurally characterized and it belongs to only a handful of complexes having nitrito-bound mononuclear copper(II) centre. The metal atom has a distorted square pyramidal geometry with the copper atom displaced from the equatorial plane by 0.25 Å. In MeCN solution the green complex exhibits a broad ligand-field transition at 655 nm with a shoulder at 675 nm and in dichloromethane-toluene glass (80 K) it exhibits an EPR spectral feature characteristic of the unpaired electron in the dx2−y2 orbital. Variable-temperature (80–300 K) magnetic susceptibility measurements in the solid state as well as room temperature measurement in MeCN solution reveal mononuclear magnetically dilute copper(II) centre. When examined by cyclic voltammetry (MeCN solution) it displays electrochemically irreversible CuII---CuI response [cathodic peak potential, Epc (V vs saturated calomel electrode (SCE)): −0.32]. An oxidative response is observed at 1.14 V, probably due to bound-nitrite oxidation and is partially removed to generate a solvated complex at the electrode surface. The latter species gives rise to reversible CuII---CuI redox response [
]. 相似文献