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991.
建立了只需一步操作即可完成在抛光洗净的金微盘阵列电极上进行多孔化处理和钯纳米粒子修饰的方法。通过对金微盘电极连续施加3个电位,分别实现金的氧化、金的还原和电沉积钯纳米粒子。利用扫描电镜和电化学方法监控制备过程,得到的结果证实了本方法的可行性和有效性。考察了溶液pH值与氧化时间对结果的影响,在磷酸盐缓冲溶液(pH7)中氧化90s,得到的修饰电极的电化学活性面积是裸电极的42倍。同时,由于整个过程不需要更换溶液,且只需开启一次仪器,大大简化了实验操作。将制备的修饰电极用于溶解氧的电催化,对溶解氧的灵敏度达到0.1mA·L/(cm2·mg),优于文献报道结果。 相似文献
992.
993.
The influences of σ* and Φ mesons,temperature and coupling constants of nucleons on the moment of inertia of the proto neutron star(PNS) are examined in the framework of relativistic mean field theory for the baryon octet {n,p,Λ,Σ+,Σ0,Σ+,Ξ-,Ξ0} system.It is found that,compared with that without considering σ* and Φ mesons,the moment of inertia decreases.It is also found that the higher the temperature,the larger the incompressibility and symmetry energy coeficient,and the larger the moment of inertia of a PNS.The influence of temperature and coupling constants of the nucleons on the moment of inertia of a PNS is larger than that of the σ* and Φ mesons. 相似文献
994.
讨论了一类三种群Beddington-DeAngelis反应食物链模型,其中第一个种群具有两阶段结构,且第二个种群对第一个种群有阶段偏食现象,得到了系统的一致持久性,进一步证明了在适当条件下,周期解及概周期解的存在性和全局渐近稳定性. 相似文献
995.
996.
In this paper, we present a simple and easily applicable approach to construct some third-order modifications of Newton's method for solving nonlinear equations. It is shown by way of illustration that existing third-order methods can be employed to construct new third-order iterative methods. The proposed approach is applied to the classical Chebyshev–Halley methods to derive their second-derivative-free variants. Numerical examples are given to support that the methods thus obtained can compete with known third-order methods. 相似文献
997.
Gui‐Zhong Yang Xiao‐Lei Chen Lu‐Min Wang Jian‐Gao Shi Chun‐Zhong Li Tianxi Liu 《先进技术聚合物》2009,20(2):104-110
A series of fluorene‐based rod–coil liquid crystal polymers with different lengths of the coil segments on backbones were designed and synthesized by a palladium‐catalyzed Suzuki coupling‐reaction. The thermal stability, the UV–Vis absorption and fluorescence spectra in chloroform solution and thin film, the electrochemical properties, thermal behavior, and morphology of these rod–coil polymers were investigated. The thermal stability of these polymers steadily decreased on increasing the length of the coil segments on the backbone; their optical and electrochemical properties did not exhibit noticeable dependence on the weight fraction of the coil segments. However, the shoulder emission and the full width at the half‐maximum (FWHM) in PL spectra of the films increased, whereas the oxidation onset potentials and the corresponding HOMO energy levels decreased with the increase in the weight fraction of the coil segments, which was assigned to microphase separation and formation of folded chain conformation as the weight fraction of the coil segments increased. These polymers displayed a characteristic liquid crystalline texture. The variation of the weight fraction of the coil segments obviously affected the thermal behavior and morphology of these rod–coil polymers. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
998.
Cao‐Yuan Niu Xian‐Fu Zheng Ling‐Ling Bai Xiao‐Ling Wu Chun‐Hong Kou 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(9):m305-m307
This study presents new coordinating modes of a Schiff base with three coordinating groups and an interesting two‐dimensional framework based on two types of constructing units. In the title compound, {[Ag(C14H10N4O)]ClO4}n, the AgI ion is coordinated by three N atoms and one O atom from three different N′‐(4‐cyanobenzylidene)isonicotinohydrazide (L) ligands, forming a primary distorted square‐planar coordination geometry. Two ligands each bridge two metal centres through one carbonitrile N atom in a monodentate mode and the hydrazide N and O atoms in a bidentate mode to form a small centrosymmetric (2+2)‐Ag2L2 ring as a principal constructing unit. The pyridyl N atoms from four ligands in four of these small rings coordinate to Ag atoms in adjacent rings to form a large hexanuclear silver grid. A two‐dimensional framework of rectangular grids is constructed from these small rings and large grids. Two perchlorate anions are located in each large grid and are bound to the grid by N—H...O hydrogen bonding. Crosslinking between the layers is achieved through long Ag...O interactions between the perchlorate anions and Ag atoms in adjacent layers. 相似文献
999.
1000.