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941.
1XZ 20/30W二代微光像增强器的设计与研制 总被引:2,自引:2,他引:0
本文分两部分论述了1XZ20/30W二代微光像增强器的设计与研制:(1)1XZ20/30W二代微光像增强器设计参数的确定原则和方法,(2)1XZ20/30W二代微光像增强器电子光学系统设计计算及性能分析。1XZ20/30W二代微光像增强器的设计,是吸取国内外同类产品的优点,结合我国的现实情况进行设计的。研制结果表明,本设计计算方法正确,结构设计合理,技术性能优越,工艺技术先进,环境试验可靠。并且零件、材料基本立足于国内,适于大批量生产,并能够与国际上同类产品10-XX1383互换使用,达到80年代国际同类产品的先进水平。 相似文献
942.
943.
Summary The applicability of alumina as a stationary phase in liquid chromatography is considered. Despite the presence of hydroxyl groups on wetted alumina, chemical modification with silanes by analogy to silica is not successful. Although depolarisation can be achieved with hexamethyldisilazane, the product is not stable to hydrolysis in aqueous media. The use of alumina as an ion-exchanger is more promising, especially because alumina appears to be stable over a very broad pH range. As a result of its amphoteric character alumina can be used either as an anion-exchanger or as a cation-exchanger. The latter possibility is more profitable in alkaline solvents and allows the separation of strongly basic compounds at pH values as high as 12. Retention can be controlled by judicious choice of ionic strength, counter ion and pH. 相似文献
944.
基于支持向量机测定水质中硝酸盐含量 总被引:2,自引:0,他引:2
针对水质中被测物硝酸盐与干扰物铁离子、铬离子紫外吸收谱线严重重叠的问题,将支持向量机应用于混合重叠光谱分析中,利用核函数将重叠的光谱数据进行高维空间变换后求得SVM回归模型,实现硝酸盐含量的光谱检测。实验结果表明:硝酸盐浓度在0.5—10mg/L范围内,所测得含量的最大相对误差为3.2%;平均回收率为100.9%,本法与传统的方法相比,要求条件较低,不需要物理或化学的分离,分析速度快,有望应用于在线监测污水中硝酸盐的含量。 相似文献
945.
946.
947.
Ribeiro MF Dias AC Santos JL Lima JL Zagatto EA 《Analytical and bioanalytical chemistry》2006,384(4):1019-1024
A novel strategy for utilization of solid reagents in flow analysis is proposed. Establishment of diffuse and reproducible
geometry enables the solid particles to be maintained in constant floating, reflux, and circulating motion inside a mini-chamber.
This is efficiently accomplished with pulsed flows, a characteristic of multi-pumping flow systems. Drawbacks inherent in
solid-phase packed columns, for example backpressure, preferential pathways, swelling, etc., and some limitations inherent
in immobilized reagents are minimised. Spectrophotometric determination of zinc in plants was selected as an application of
the technique. Dowex 1-X8 anionic resin was kept freely inside a mini-chamber. Zinc chloro-complexes were adsorbed on the
moving particles and derivatization with zincon was performed after elution. Analytical figures of merit and the potential
and limitations of the approach are discussed. 相似文献
948.
Drexler D Barlow DJ Falk P Cantone J Hernandez D Ranasinghe A Sanders M Warrack B McPhee F 《Analytical and bioanalytical chemistry》2006,384(5):1145-1154
Fluorescence detection has been a method of choice in industry for screening assays, including identification of enzyme inhibitors,
owing to its high-throughput capabilities, excellent reproducibility, and sensitivity. Occasionally, inhibitors are identified
that challenge the fluorescence assay limit, necessitating the development of more sensitive detection methods to assess these
compounds. For data mining purposes, however, original assay conditions may be required. A direct method transfer to highly
sensitive and specific LC-MS-based methods has not always been possible due to the presence of MS-incompatible neutral detergents
and non-volatile salts in the assay matrix. Utilizing an in vitro proteolytic screening assay for the serine protease hepatitis C virus (HCV) nonstructural (NS) 3 protease as a test case,
we report the development of an automated sample clean-up procedure implemented on-line with liquid chromatography–tandem
mass spectrometry (LC-MS/MS) analysis to complement fluorescence detection. Ion exchange and peptide microtraps were employed
to remove MS-incompatible assay matrix components. Three protease inhibitors were used to validate the MS/MS method. Comparable
potencies were achieved for these compounds when assessed by fluorescence and MS/MS detection. Furthermore, four-fold less
enzyme could be utilized when employing the MS/MS method compared to fluorescence detection. The longer analysis time, however,
resulted in reduced sample capacity. The potency of our designed HCV NS3 protease inhibitors are thus routinely evaluated
using a continuous fluorescence-based assay. Only pertinent inhibitors approaching the fluorescence assay sensitivity limit
are subsequently analyzed further by LC-MS/MS. This methodology allows us to maintain a database and to compare results independent
of the detection method. Despite the relatively slow sample turnaround time of this LC-MS approach, the versatility of the
automated on-line clean-up procedure and sample analysis can be applied to assays containing reagents which were historically
considered to be MS incompatible. 相似文献
949.
High density polyethylene (HDPE) has been modified by Ag+ ion implantation with the energy of 60 keV. The total amount of implanted silver ions was 1, 5 and 12 × 1015 ions/cm2. The surface topography was observed by atomic force microscopy (AFM), while the surface composition changes were detected using phase imaging AFM. Surface topography changes were studied in detail using 3D surface parameters analyses. The average roughness decreased for the implanted HDPE indicating the flattening of the surface. Phase AFM images indicated the homogenization of the polyethylene during ion implantation, while histogram analyses confirmed the change in surface composition. 相似文献
950.
Abdelmoutalib Metrane François Soumis Issmail Elhallaoui 《European Journal of Operational Research》2010
In this paper, we propose a new Dantzig–Wolfe decomposition for degenerate linear programs with the non degenerate constraints in the master problem and the degenerate ones in the subproblem. We propose three algorithms. The first one, where some set of variables of the original problem are added to the master problem, corresponds to the Improved Primal Simplex algorithm (IPS) presented recently by Elhallaoui et al. [7]. In the second one, some extreme points of the subproblem are added as columns in the master problem. The third algorithm is a mixed implementation that adds some original variables and some extreme points of a subproblem to the master problem. Experimental results on some degenerate instances show that the proposed algorithms yield computational times that are reduced by an average factor ranging from 3.32 to 13.16 compared to the primal simplex of CPLEX. 相似文献