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71.
本文报道由H2PDC合成的新型维层状无机-有机骨架晶体Ni(PDC)(H2O)2(H2PDC=吡啶-2,5-二羧酸), 该化合物的一层是由右手螺旋Ni—O—C链与左手螺旋Ni-pdc链组成, 而邻近的一层则是由左手螺旋Ni—O—C链与右手螺旋Ni-pdc链组成, 层与层之间通过氢键作用形成了三维超分子结构. 用ICP、TG、IR和X射线单晶衍射分析等手段对其结构进行表征. 相似文献
72.
CrMCM-41分子筛的合成与表征 总被引:9,自引:0,他引:9
直接合成了含铬 MCM- 4 1中孔 (mesoporous)分子筛 ;通过 XRD、骨架 IR、ESR、紫外漫反射(DRS)、2 9Si MASNMR等测试 ,表明铬处在分子筛骨架上 ,同时也存在非骨架铬。骨架红外光谱中除发现铬分子筛的特征峰 690 cm-1 外 ,还发现被归属于 O3 Si- O- T振动的吸收峰 960 cm-1 ;ESR中观察到 g=2 .4处有信号 ,可能与骨架铬直接有关 ;固体魔角核磁 2 9Si谱也进一步证实骨架铬的存在。同时对 Cr MCM- 4 1分子筛的热稳定性、吸附量和酸性进行了考察。 相似文献
73.
A method is described for the simultaneous quantitative determination of monoamines and related compounds from urine and brain tissue samples in the pg-range, using a GC/MF instrument LKB-2091 provided with a multiple ion detection (MID) system and capillary columns. The simultaneous detection of “fingerprints” with fourteen and more compounds during one single GC run was achieved after the intoduction of “time gates” for the detection of the different characteristic masses. Several modifications to the LKB equipment permitted exact reproducibility of retention times, which is essential for the use of “time gates”. The detection of “fingerprints” with these acidic, basic and alcoholic substances was achieved by the extraction of the dried biological samples with silylating agents. 相似文献
74.
The new nickel selenite chloride, Ni5(SeO3)4Cl2, was obtained by high-temperature solid state reaction of NiCl2, Ni2O3 and SeO2 in a 1:2:4 molar ratio at 700 °C in an evacuated quartz tube. Its structure was established by single-crystal X-ray diffraction. Ni5(SeO3)4Cl2 crystallizes in the triclinic system, space group P-1 (No. 2) with cell parameters of a=8.076(2), b=9.288(2), c=9.376(2) Å, α=101.97(3), β=105.60(3), γ=91.83(3)° and Z=2. All nickel(II) ions in Ni5(SeO3)4Cl2 are octahedrally coordinated by selenite oxygens or/and chloride anions (([Ni(1)O5Cl], [Ni(2)O4Cl2], [Ni(3)O5Cl], [Ni(4)O6] and [Ni(5)O4Cl]). The structure of the title compound features a condensed three-dimensional (3D) network built by Ni(II) ions interconnected by SeO32− anions as well as Cl− anions. Magnetic property measurements show strong antiferromagnetic interaction between nickel(II) ions. 相似文献
75.
76.
Hai-Long Jiang 《Journal of solid state chemistry》2006,179(6):1911-1917
Two new barium zinc selenite and tellurite, namely, BaZn(SeO3)2 and BaZn(TeO3)Cl2, have been synthesized by the solid state reaction. The structure of BaZn(SeO3)2 features double chains of [Zn(SeO3)2]2− anions composed of four- and eight-member rings which are alternatively along a-axis. The double chains of [Zn2(TeO3)2Cl3]3− anions in BaZn(TeO3)Cl2 are formed by Zn3Te3 rings in which each tellurite group connects with three ZnO3Cl tetrahedra. BaZn(SeO3)2 and BaZn(TeO3)Cl2 are wide bandgap semiconductors based on optical diffuse reflectance spectrum measurements. 相似文献
77.
Mahmoud M. Al Omari Mohammad B. Zughul J. Eric D. Davies Adnan A. Badwan 《Journal of inclusion phenomena and macrocyclic chemistry》2006,54(3-4):159-164
Ternary complexes exploiting solubility synergism (SSn) between basic drugs and β-cyclodextrin (β-CD) in the presence of an organic hydoxy acid have been reported to provide the pharmaceutical technology with highly soluble ternary complexes, even with the least soluble β-CD. In this work, phase solubility techniques were used to study factors affecting SSn in aqueous solution, which may help in understanding the mechanism involved in ternary complex formation in solution, under equilibrium conditions. The equilibrium solubility of both β-CD and each of 8 structurally unrelated drugs were measured in tandem in the presence of different acid types at low and high pHs, and at different time intervals over a period of 1–40 days. The results indicate that SSn is evident regardless of acid type (organic and inorganic) at low pH, but the extent of SSn is acid type dependant and is limited by the drug salt solubility product constant (pK
sp). Among different drugs, no apparent trend exists between drug salt solubility and the extent of SSn, but lowering drug salt solubility by increasing pH depresses SSn. The results also reveal no apparent trend between the magnitude of the complex formation constant (K
ij) and SSn. For example, drugs of low K
ij values such as astemizole, cisapride and sildenafil do not show any SSn, yet ketotifen and pizotifen, which also have low K
ij values, exhibit substantial SSn. However, the solublizing power of β-CD represented by the slope of phase solubility diagram can be used as a marker for SSn (slopes exceeding 0.4 induce SSn). 相似文献
78.
79.
《Journal of polymer science. Part A, Polymer chemistry》2018,56(16):1868-1877
Self‐immolative polymers (SIPs) undergo depolymerization in response to the cleavage of stimuli‐responsive end‐caps from their termini. Some classes of SIPs, including polycarbamates, have depolymerization rates that depend on environmental factors such as solvent and pH. In previous work, hydrophobic SIPs have been incorporated into amphiphilic block copolymers and used to prepare nanoassemblies. However, stimuli‐responsive hydrophilic blocks have not previously been incorporated. In this work, we synthesized amphiphilic copolymers composed of a hydrophobic polycarbamate SIP block and a hydrophilic poly(2‐(dimethylamino)ethyl methacrylate) (PDMAEMA) block connected by a UV light‐responsive linker end‐cap. It was hypothesized that after assembly of the block copolymers into nanoparticles, chain collapse of the PDMAEMA above its lower critical solution temperature (LCST) might change the environment of the SIP block, thereby altering its depolymerization rate. Self‐assembly of the block copolymers was performed, and the depolymerization of the resulting assemblies was studied by fluorescence spectroscopy, dynamic light scattering, and NMR spectroscopy. At 20 °C, the system exhibited a selective response to the UV light. At 65 °C, above the LCST of PDMAEMA, the systems underwent more rapid depolymerization, suggesting that the increase in rate arising from the higher temperature dominated over environmental effects arising from chain collapse. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1868–1877 相似文献
80.
Mark P. Waller Thomas Dresselhaus Jack Yang 《Journal of computational chemistry》2013,34(16):1420-1428
Here, we present just a collection of beans (JACOB): an integrated batch‐based framework designed for the rapid development of computational chemistry applications. The framework expedites developer productivity by handling the generic infrastructure tier, and can be easily extended by user‐specific scientific code. Paradigms from enterprise software engineering were rigorously applied to create a scalable, testable, secure, and robust framework. A centralized web application is used to configure and control the operation of the framework. The application‐programming interface provides a set of generic tools for processing large‐scale noninteractive jobs (e.g., systematic studies), or for coordinating systems integration (e.g., complex workflows). The code for the JACOB framework is open sourced and is available at: www.wallerlab.org/jacob . © 2013 Wiley Periodicals, Inc. 相似文献