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991.
应用等离子体辅助煤气化反应装置对大同煤进行了实验研究,考察了供气量、供粉速率、发生器输入功率、水蒸气压力以及添加不同质量分数的CaCO3 和CaO对煤气化反应的影响,并对不同条件下产品气体的组成进行了分析。实验结果表明,装置的最佳工艺参数为供煤速率150 g/min、供气量18 m3/h、等离子体发生器输出功率100 kW、水蒸气出口压力0.3 MPa。加入添加剂CaCO3和CaO的质量分数分别为10%和5%时,催化效果最好。根据CaCO3和CaO的实验数据可知,在等离子体辅助煤气化过程中CaCO3起催化作用为主,CO2还原为辅。 相似文献
992.
Lewis base could catalyze the formation of a-trifluoromethyl alcohol from CF3SiMe3 and carbonyl-containing compounds. It was found that the α-trifluoromethyl alcohol could also be used to promote the synthesis in basic conditions. 相似文献
993.
Growth of single-crystalline Ni and Co nanowires via electrochemical deposition and their magnetic properties 总被引:2,自引:0,他引:2
Pan H Liu B Yi J Poh C Lim S Ding J Feng Y Huan CH Lin J 《The journal of physical chemistry. B》2005,109(8):3094-3098
Single-crystalline Ni nanowires have been successfully fabricated with anodic aluminum oxide as template by electrodeposition. Structural characterization (X-ray diffraction, XRD, and high-resolution transmission electron microscopy, HRTEM) shows that the single-crystalline Ni nanowire has a preferred orientation along the [220] direction. The effects of electrochemical deposition conditions on the structure of Ni nanowires are systematically studied to investigate the growth mechanism. Possible reasons for the growth of the single-crystalline Ni nanowires were discussed on the basis of electrochemistry and thermodynamics. These single-crystalline Ni nanowires have exhibited excellent magnetic properties (large anisotropy, large coercivity, and high remanence). By a similar process, single-crystalline Co nanowires with hexagonal close-packed (hcp) structure were achieved, also having large anisotropy, large coercivity (1.8 kOe), and high remanence ratio (80.8%). 相似文献
994.
Liang Yin Chao Feng Wang Huan Ling Wang Rong Li Jian Tai Ma 《中国化学快报》2007,18(12):1487-1489
New Frechet-type dendritic BINOL ligands bearing several BINOL units at the periphery have been successfully synthesized. The (dendritic BINOL) Ti(IV) complexes were proved to be efficient catalysts for the enantioselective addition of diethylzinc to aromatic aldehydes. Moreover, these ligands could be quantitatively recovered and reused at least five times without a loss of the yield and enantioselectivity. 相似文献
995.
996.
纳米材料的自组装研究进展 总被引:15,自引:0,他引:15
本文主要评述了近年来纳米材料自组装的研究进展,即对以纳米材料(包括零维的纳米粒子和一维的纳米管/线)为单元而开展的自组装方面的工作进行了介绍。将纳米材料自组装为各种尺度的有序结构会产生更优异的整体的协同性质,这对于以纳米材料为基础而构筑的微纳米器件有着重要的意义。由于目前纳米材料的研究主要集中在零维和一维体系,因此,本文分别就此两种体系的自组装行为进行了评述。具体内容包括:单分子层薄膜修饰的无机纳米粒子的自组装、大分子修饰的无机纳米粒子的自组装、未被修饰的无机纳米粒子的自组装;表面张力及毛细管力诱导的一维纳米材料的自组装、模板诱导的一维纳米材料的自组装、静电力诱导的一维纳米材料的自组装。 相似文献
997.
An analytical study of the steady electrokinetic flow in a long uniform capillary tube or slit is presented. The inside wall of the capillary is covered by a layer of adsorbed or covalently bound charge-regulating polymer in equilibrium with the ambient electrolyte solution. In this solvent-permeable and ion-penetrable surface polyelectrolyte layer, ionogenic functional groups and frictional segments are assumed to distribute at uniform densities. The electrical potential and space charge density distributions in the cross section of the capillary are obtained by solving the linearized Poisson-Boltzmann equation. The fluid velocity profile due to the application of an electric field and a pressure gradient through the capillary is obtained from the analytical solution of a modified Navier-Stokes/Brinkman equation. Explicit formulas for the electroosmotic velocity, the average fluid velocity and electric current density on the cross section, and the streaming potential in the capillary are also derived. The results demonstrate that the direction of the electroosmotic flow and the magnitudes of the fluid velocity and electric current density are dominated by the fixed charge density inside the surface polymer layer, which is determined by the regulation characteristics such as the dissociation equilibrium constants of the ionogenic functional groups in the surface layer and the concentration of the potential-determining ions in the bulk solution. 相似文献
998.
Pan Li ZhangXiao Feng Deng Ye Wang Huan Wu DaGang LuoXiao Dong 《Helvetica chimica acta》2003,86(7):2525-2532
Four new jatrophane diterpenoids, altotibetin A ( 1 ), altotibetin B ( 2 ), altotibetin C ( 3 ), altotibetin D ( 4 ), and nine known compounds, β‐sitosterol, cycloart‐23‐ene‐3β,25‐diol, cycloart‐25‐ene‐3β,24‐diol, lupeol acetate, scopoletin, kaempferol, uracil, uridine, astragalin, and daucosterol have been isolated from the whole plant of Euphorbia altotibetic Pauls . Their structures were established by spectral methods, and the configurations of 1 and 2 were confirmed by X‐ray analysis. 相似文献
999.
A combined analytical-numerical study is presented for the quasisteady photophoretic motion of a spherical aerosol particle of arbitrary thermal conductivity and surface properties exposed to a radiative flux perpendicular to a large plane wall. The Knudsen number is assumed to be so small that the fluid flow is described by a continuum model with a temperature jump, a thermal slip, and a frictional slip at the surface of the radiation-absorbing particle. In the limit of small Peclet and Reynolds numbers, the appropriate equations of conservation of energy and momentum for the system are solved using a boundary collocation method and numerical results for the photophoretic velocity of the particle are obtained for various cases. The presence of the neighboring wall causes two basic effects on the particle velocity: first, the local temperature gradient on the particle surface is enhanced or reduced by the wall, thereby speeding up or slowing down the particle; second, the wall increases viscous retardation of the moving particle. The net effect of the wall can decrease or increase the particle velocity, depending upon the relative conductivity and surface properties of the particle as well as the relative particle-wall separation distance. In general, the boundary effect of a plane wall on the photophoresis of an aerosol particle can be quite significant in some situations. In most aerosol systems, the boundary effect on photophoresis is weaker than that on the motion driven by a gravitational field. 相似文献
1000.