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21.
过渡金属酞等配合物(MPC)用手均相液相氧化中作催化剂已有不少报导,象许多均相催化剂一样,MPC用于均相反应存在着难于从反应体系中分离出来的问题.把均相配合物催化剂固载在无机氧化物如硅股或有机高分子载体上是解决这一问题的一种方法.我们曾尝试把MP。固载在分子筛载体和硅胶载体上,并用ESR研究其对O2的活化作用[1,2].本文报导MPc通过共价键键联固载在SiO2上,并研究其对O2的活化作用.1实验部分1.1试剂HSIC13为日本东京化成株式会社产品,二级试剂·发烟硫酸(SO。质量分数大于20%)为分析纯试剂.PCl5为化学纯试… 相似文献
22.
Jiyun Hu Hamed Mehrabi Yin-Shan Meng Maddison Taylor Jin-Hui Zhan Qigeng Yan Mourad Benamara Robert H. Coridan Hudson Beyzavi 《Chemical science》2021,12(22):7930
Metalation of covalent organic frameworks (COFs) is a critical strategy to functionalize COFs for advanced applications yet largely relies on the pre-installed specific metal docking sites in the network, such as porphyrin, salen, 2,2′-bipyridine, etc. We show in this study that the imine linkage of simple imine-based COFs, one of the most popular COFs, readily chelate transition metal (Ir in this work) via cyclometalation, which has not been explored before. The iridacycle decorated COF exhibited more than 10-fold efficiency enhancement in (photo)catalytic hydrogen evolution from aqueous formate solution than its molecular counterpart under mild conditions. This work will inspire more functional cyclometallated COFs to be explored beyond catalysis considering the large imine COF library and the rich metallacycle chemistry.This study describes cyclometallation as a new metal binding mode for imine-based COFs. The iridacycle decorated COF could be used for catalytic hydrogen evolution from aqueous formate solution with high stability and high efficacy. 相似文献
23.
The hydrothermal reaction of NaVO(3).H(2)O, barbituric acid, NH(2)NH(2).2HCl, H(3)PO(4), and H(2)O gave a novel heteropolyoxovanadate Na(6)[(P(V)O(4))V(V)(6)V(IV)(12)O(39)](2).H(3)PO(4).31H(2)O (1) and an unexpected phase Na(2)[C(12)H(6)N(6)O(9)].7H(2)O (2). The basic building blocks in 1 are the six-capped sphere-shaped heteropoly anion [(P(V)O(4))V(V)(6)V(IV)(12)O(39)](3-) with framework similar to that of the reported polyoxovanadates possessing [V(18)O(42)] clusters encapsulating VO(4) or other ions. These heterpoly anionic units are linked via V[bond]O[bond]V bridges into an interesting 3D straight-channel structure. The structure of 2 consists of novel organic anions ([C(12)H(6)N(6)O(9)](2-), 5,5-bis(2',4',6'-trioxopyrimidyl)barbital, representing the first oxidized barbituric acid trimer) linked via sodium ions into 1D hollow tubes with diameter of 4.49 x 6.86 A and further connected into a three-dimensional framework via hydrogen bonds. 相似文献
24.
在硼氢化钾碱性溶液中对金属氢化物(MH)电极的表面进行化学还原处理,提高了MH电极的放电容量、活化性能和电催化活性.用其为负极组装的AA型MH-Ni电池进行了封口化成,电池放电容量达到1150mAh,5C下电池的放电容量达到0.2C下容量的80%以上,电池在1C100%DOD(放电深度)充放电条件下,循环寿命由原来的100次左右提高到200次以上 相似文献
25.
Based on carbon nanofibers (CNFs) as a solid phase extraction adsorbent, a microcolumn preconcentration method coupled to inductively coupled plasma mass spectrometry (ICP–MS) was developed for the determination of trace elements (Mn, Co and Ni). The effect of various experimental parameters such as pH, sample flow rate and volume, elution solution and interfering ions on the retention of the studied ions have been investigated systematically. During all the steps of the experimental process, Mn, Co and Ni could be quantitatively sorbed on the microcolumn containing CNFs in the range of pH 6.0–9.0, and then eluted completely with 0.5 mol ml− 1 HNO3. A preconcentration factor of 150-fold was obtained. The detection limits for Mn, Co and Ni were 40, 0.4 and 8.0 pg ml− 1, respectively, with relative standard deviations less than 6.0%. In order to validate the proposed method, two certified reference materials of human hair (GBW 07601) and mussel (GBW 08571), and water sample were analyzed with satisfactory results. The recoveries were between 95.0 and 114%. 相似文献
26.
Self-assembled multilayer thin films have been prepared on Au substrate by alternate surface derivatization with L-cysteine hydrochloride and cupric perchlorate. The layer-by-layer structure at each step of multilayer formation was investigated by X-ray photoelectron spectroscopy. The measurements indicate that there are two structure modes in the multilayers. One is that Cu(2+) sandwiches between two amino acid groups. The other one is that Cu(+) is bonded through disulfide and thiolate. This process is also confirmed by cyclic voltammetry of Cu ion at different self-assembled multilayers. Steps further on will lead to repeated multilayer films. 相似文献
27.
28.
文中采用机械合金化(MA)和氢化燃烧法(HCS)制备了Mg1.9Al0.1Ni,通过对它们储氢性能的对比研究发现,MA优于HCS.采用MA制得的Mg1.9Al0.1Ni储氢合金具有较高的活性和高储氢量,对PCT结果进行计算,得出温度和氢平衡压的关系式.Mg1.9Al0.1Ni(MA)553K时100s内吸放氢量分别为2.67和2.54 mass%H.用XRD方法进行物相分析,表明添加适量Al没有改变Mg2Ni的物相结构,由于MA能够制备出纳米晶粒,使得Mg1.9Al0.1Ni合金具有更好的储放氢动力学性能. 相似文献
29.
Three new alkaloids, longistylumphyllines A–C (1–3), together with the six known alkaloids deoxycalyciphylline B, deoxyisocalyciphylline B, methyl homosecodaphniphyllate, daphnicyclidin A, daphnicyclidin B, and daphnicyclidin F, were isolated from the stems and leaves of Daphniphyllum longistylum. Their structures and relative configuration were elucidated on the basis of spectroscopic data, especially 1D and 2D NMR techniques. 相似文献
30.
Chang–Guo Zhan 《International journal of quantum chemistry》1992,44(2):123-140
This paper provides a brief and systematic presentation of the basic principle and method of the maximum overlap symmetry molecular orbital (MOSMO ) model and its application to simplification of molecular orbital calculation and to calculation of molecular structures and properties, together with some new results about the MOSMO calculation and new insights concerning the further extension of the principle and method. It has been shown that the theoretical method of the MOSMO model is very simple, reliable, and useful and can be employed to study the structure–property relation in even very large molecular systems. The numerical results obtained from the MOSMO calculation on various semiempirical molecular orbital approximation levels show that when the same parametrization, such as one of those employed in EHMO , CNDO /2, and HMO methods, is adopted, the MOSMOS are very close to the canonical molecular orbitals obtained from the customary LCAO method and the MOSMO calculation requires less computing time than does the LCAO method. The MOSMO calculation can be used for rapidly obtaining reasonably good molecular geometries, vibrational frequencies, and other properties of molecules by employing a simple improved semiempirical parametrization. Equilibrium geometries, vibrational frequencies, and other results are in good agreement with the experimental data and the results obtained from ab initio molecular orbital calculation. The basic calculational procedure of the MOSMO model can be extended further and has been employed to give some new results, to propose some new theoretical schemes and principles, and to introduce some new interesting theoretical problems that deserve to be studied further. 相似文献