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991.
Summary The influence of different reversed-phase packings and the addition of acidic modifiers to the mobile phase was observed on
the separation of basic and neutral polypeptide antibiotics by gradient elution. A dependence of pore size, coverage, reaction
type and endcapping of the packings was not observed. Nevertheless, not all reversed-phase packings were suitable for the
separation of polypeptides, especially of basic molecules. The addition of phosphoric or perchloric acid to the mobile phase
prevented adsorption of the basic polypeptide antibiotics on the stationary phase. 相似文献
992.
MichaŁ Rozwadowski Roman Wojsz 《Journal of inclusion phenomena and macrocyclic chemistry》1989,7(5):561-567
Fundamental thermodynamic functions have been derived for equations of adsorption isotherms including structural heterogeneity connected with micropore dimensions. Good agreement has been achieved between values of the differential molar enthalpy of adsorption and values of the isosteric adsorption heats obtained experimentally. 相似文献
993.
As the first systematic study dealing with the adsorption of estrogens by granular activated carbon (GAC), the removal behavior of 17β-estradiol (E2) and its biotransformation product of estrone (E1) in fixed GAC columns was examined using four biological activated carbon (BAC) columns (BAC-1~BAC-4) generated by coating four GAC columns with detached microorganisms from the riverbed sediment of a representative drinking river water source containing lower content of natural organic matter (NOM). For comparison, parallel adsorption experiments were also performed using another four GAC columns (GAC-1~ GAC-4) packed by strictly following the configurations of four BAC columns. Adsorption experimental results obtained by intermittently spiking E2 over a total running period about 350 days into the river water mixed with or without a peaty water containing higher content of NOM showed that E2 was readily removed by adsorption and the combined adsorption/biodegradation. The vertical profiles of E2 and E1, which have great significance for better understanding and optimization of the adsorption process for removal of human estrogens, were also obtained. 相似文献
994.
Yan Levin 《Journal of statistical physics》2003,110(3-6):825-834
In this contribution to the special issue of the Journal of Statistical Physics dedicated to Michael Fisher on his 70th birthday, I shall review two thermodynamically distinct routes for obtaining the interfacial tension of liquid-vapor interfaces in mixtures. A specific application to the calculation of excess surface tension of aqueous electrolyte solutions will be presented. 相似文献
995.
Frederik Tielens 《Surface science》2006,600(2):357-365
Periodic-DFT has been used to study the acid-base properties of MgO(1 0 0) layers interconnected with an ice filling. The insertion of HCl by substitution of one water molecule shows that all the protons are adsorbed on the surface oxygen atoms forming hydroxyl groups; the Cl− ions are weakly bound to surface cations, generating a monolayer with the adsorbed water molecules. For the insertion of NaOH also by substitution of one water molecule, it is found that OH− ions remain in solution close to the Na+ ions, forming ion pairs or chains. Depending on the number of water molecules present, the sodium ions are bi-, tri- or tetra-coordinated. Finally, some aspects concerning corrosion have been highlighted. 相似文献
996.
We present results of ab initio theoretical investigations of the structural and dynamical properties of the Se:InP(1 1 0) and Te:InP(1 1 0) surfaces, by employing the plane wave pseudopotential method, the local density approximation of the density functional theory, and a linear response scheme. For both adsorbates we have used the so-called exchange geometry (the chalcogen atoms replacing P in the top two atomic layers). A detailed discussion is provided of the relaxed surface geometry and phonon dispersion curves along two principal symmetry directions. It is found that the adsorption of Se (or Te) atoms on InP(1 1 0) leads to phonon modes in the acoustic-optical gap region for bulk InP. The characteristic atomic displacement patterns of selected phonon modes on these surfaces have been compared and contrasted with those on the clean InP(1 1 0) surface. 相似文献
997.
Molecular monolayers of zinc porphyrins deposited from a liquid solution on mica substrates have been characterised using atomic force microscopy (AFM). At room temperature, needle-shaped single layer porphyrin islands are formed due to an anisotropic growth rate. The average island size depends on the concentration of the porphyrin solution, but the length to width aspect ratio is rather independent of the island size. Annealing the porphyrin monolayers to 450 K leads to the reduction of the size of the monolayer islands in two different ways depending on the heating rate. With slow heating rate, the island size was found to shrink by losing molecules from the edge of the island. With high heating rate, nanoscale molecular clusters were found to form. 相似文献
998.
牛红细胞铜锌超氧化物歧化酶(BESOD)在汞电极表面吸附行为的研究钱雯,孟庆国,罗勤慧,沈孟长(南京大学配位化学研究所,配位化学国家重点实验室南京,210093)关键词铜锌超氧化物歧化酶,吸附,循环伏安,双阶跃计时电量超氧化物歧化酶是超氧离子(·O)... 相似文献
999.
H2PdCl4在纤维素基磁性聚偕胺肟树脂上的吸附是一个复杂的过程。在生成AO-H2pDcL4络合物时伴随着外加酸的竞争吸附、物理吸附和氧化还原作用等副反应。物理扩散和化学吸附均非吸附速度的控制阶段,表现为快的吸附速度,接触5分钟时,讨论了吸附机理。 相似文献
1000.
煤层气(矿井瓦斯)是一种有望替代传统化石燃料,如煤、石油和天然气的非常规气体. 作为可得的清洁能源,它的利用被认为是节能和经济的选择. 在本工作中,非金属原子X(X=H,O,N,S,P,Si,F,Cl)修饰的石墨烯(Gr)被用来代表具有结构异性的煤表面模型. 通过密度泛函理论系统地研究了煤层气组分Y(Y=CH4,CO2,H2O)在非金属原子修饰石墨烯上的吸附作用. 结果表明Y在非金属原子修饰石墨烯上的吸附均为物理吸附. 态密度和差分电荷密度共同表明了这种弱的相互作用.其中,H和Cl对CH4的作用较大; N、O、F、Cl对CO2的作用较强; N,Cl对H2O的影响不容忽视. 总的来说,吸附能大小依次为:H2O>CO2>CH4. 因此,在CH4富集的煤层里注入H2O或CO2可以与CH4形成竞争吸附,进而提高煤层气采收率. 本工作提供了在分子水平下煤层气与非金属原子修饰石墨烯之间的相互作用的详情,并为煤层瓦斯的开采与分离提供了有用的信息. 相似文献