全文获取类型
收费全文 | 643篇 |
免费 | 26篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 5篇 |
妇产科学 | 9篇 |
基础医学 | 137篇 |
口腔科学 | 6篇 |
临床医学 | 68篇 |
内科学 | 73篇 |
皮肤病学 | 5篇 |
神经病学 | 43篇 |
特种医学 | 69篇 |
外科学 | 18篇 |
综合类 | 61篇 |
预防医学 | 40篇 |
眼科学 | 3篇 |
药学 | 96篇 |
中国医学 | 21篇 |
肿瘤学 | 28篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 8篇 |
2021年 | 10篇 |
2020年 | 21篇 |
2019年 | 13篇 |
2018年 | 21篇 |
2017年 | 18篇 |
2016年 | 12篇 |
2015年 | 25篇 |
2014年 | 24篇 |
2013年 | 39篇 |
2012年 | 27篇 |
2011年 | 49篇 |
2010年 | 26篇 |
2009年 | 33篇 |
2008年 | 30篇 |
2007年 | 28篇 |
2006年 | 23篇 |
2005年 | 18篇 |
2004年 | 11篇 |
2003年 | 19篇 |
2002年 | 9篇 |
2001年 | 10篇 |
2000年 | 13篇 |
1999年 | 6篇 |
1998年 | 15篇 |
1997年 | 18篇 |
1996年 | 16篇 |
1995年 | 22篇 |
1994年 | 9篇 |
1993年 | 4篇 |
1992年 | 15篇 |
1991年 | 13篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 11篇 |
1984年 | 11篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1977年 | 4篇 |
1975年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有683条查询结果,搜索用时 15 毫秒
1.
2.
D. A. CROOKS 《Neuropathology and applied neurobiology》1991,17(5):421-424
The quantitation of diffuse axonal injury provides a more objective approach to the assessment of tissue damage in head injuries. The method designed in this study takes into account the anisotropy and structural inhomogeneity of the brain, and the distribution of lesions in diffuse axonal injury. The number of counts required for the statistical analysis is inversely proportional to the square of the desired accuracy, specified as the percentage of the mean value of the axonal balloons since the true mean is unknown from the outset. The number of fields are examined using an indexed-squares graticule in 10 different areas of the brain. Silver-stained sections from the brains of head injured patients that survived longer than 12 h must be used with this method. Difficulties may arise when patients of different survival times are compared since it takes some time for the axonal balloons to develop. A correlation with the survival time can be established with the quantitative data collected. The morphometric principles and the statistical rationale on which this methodology is based are briefly presented. 相似文献
3.
Brian J. Soher Peter C. M. van Zijl Jeffrey H. Duyn Peter B. Barker 《Magnetic resonance in medicine》1996,35(3):356-363
Multislice proton MR spectroscopic images (SI) of the brain were quantitated, using the phantom replacement technique. In 16 normal volunteers, ranging in age from 5 to 74 years, average “whole brain” concentrations of choline (Cho), creatine (Cr), and N-acetylaspartate (NAA) were found to be 2.4 ± 0.4, 7.9 ± 1.3, and 11.8 ± 1.0 (mM, mean ± SD), respectively. These values are in good general agreement with those previously determined by single-voxel localization techniques. Cortical gray matter was found to have lower Cho and NAA levels, compared to those of white matter, corpus callosum, and basal ganglia. Cho was also found to increase significantly with age in several locations. Quantitative multislice proton SI is feasible in the clinical environment, and regional and age-dependent variations occur that must be accounted for when evaluating spectra from pathological conditions. 相似文献
4.
Greg Reynolds Martin Wilson Andrew Peet Theodoros N Arvanitis 《Magnetic resonance in medicine》2006,56(6):1211-1219
The quantitation of metabolite concentrations from in vitro NMR spectra is hampered by the sensitivity of peak positions to experimental conditions. The quantitation methods currently available are generally labor intensive and cannot readily be automated. Here, an algorithm is presented for the automatic time domain analysis of high-resolution NMR spectra. The TARQUIN algorithm uses a set of basis functions obtained by quantum mechanical simulation using predetermined parameters. Each basis function is optimized by subdividing it into a set of signals from magnetically equivalent spins and varying the simulated chemical shifts of each of these groups to match the signal undergoing analysis. A novel approach to the standard multidimensional minimization problem is introduced based on evaluating the fit resulting from different permutations of possible chemical shifts, obtained from one-dimensional searches. Results are presented from the analysis of (1)H proton magic angle spinning spectra of cell lines illustrating the robustness of the method in a typical application. Simulation was used to investigate the biggest peak shifts that can be tolerated. 相似文献
5.
6.
A method for the accurate determination of anti-hapten cytotoxic T lymphocyte precursors: correction for apparent 'anti-self' reactivity 总被引:1,自引:0,他引:1
A method is described for accurately determining the frequency of precursors of hapten specific cytotoxic T cells. The method is based on a standard Poisson analysis of limit dilution cultures, but makes a correction of 'anti-self' reacting clones and for spontaneously arising clones that recognise modified self. These corrections are shown to be especially important when low hapten densities are used, where there may be more than a 10-fold difference between the corrected and uncorrected frequency estimates. Determined levels of antigen specificity and of H-2 restriction are significantly enhanced by application of this method. 相似文献
7.
C-reactive protein (CRP) was assessed in pediatric serum samples using different commercial latex reagents, which were analyzed for species origin of the coating antibodies, homogeneity and density of the latex particles, and prozone agglutinating capacity. All reagents correctly agglutinated the positive and negative control sera. The antibodies coating the particles differed with regard to species origin: one was coated with rabbit, one with horse and goat, one with horse, goat, rabbit and swine, while the reference reagent had horse, goat and rabbit antibodies.Only the monospecies specific antibody-coated latex showed obvious prozoning; this reagent also had the smallest and most homogenous latex particles and showed the most clear-cut reactions. False agglutination was observed at 7–26% according to quantitation with the spot immunoprecipitate assay, which compared favorably with radial immunodiffusion measurements. The lowest percentage of false readings was noted for the rabbit antibody-coated particles; the highest for the reagent with particles coated using antibodies from 4 different species.No reagent had satisfactory precision for the low positive sera between 10 and 40 mg CRP/1. 相似文献
8.
Yeung ES 《Journal of pharmaceutical and biomedical analysis》1984,2(2):255-263
A micropolarimeter interfaced to a liquid chromatograph is shown to be suitable for selective monitoring of the optically-active components in complex samples. When an optically-active eluent is used, indirect determination of even optically-inactive materials is possible, down to the level of 10 ng of an injected component. If a second chromatogram is obtained using the racemic analogue of the optically-active eluent, quantitation can be achieved without standards and without prior analyte identification. This concept is also applicable to the refractive index detector, the absorption detector and the conductivity detector in the special case of ion chromatography, and the ultrasonic detector in gas chromatography. 相似文献
9.
Production and characterization of monoclonal antibodies to guinea pig lymphoid differentiation antigens 总被引:5,自引:0,他引:5
J Chiba T M Chused W M Leiserson S E Zweig E M Shevach 《Journal of immunological methods》1983,63(2):247-261
We have prepared 2 mouse monoclonal antibodies which react with differentiation antigens on guinea pig lymphoid cells. Monoclone 5AB2 recognizes an antigen expressed on both T and B lymphocytes and absent on macrophages. It has proven useful in the preparation of populations of antigen presenting cells which are free of T and B lymphocytes. The second monoclonal, 8BE6, is specific for peripheral T cells and 10% of thymocytes. It reacts with a 68,000 dalton molecule which is also expressed on the guinea pig B cell leukemia, EN-L2C. 8BE6 has proven to be lytic for peripheral T cells in the presence of rabbit complement and has been used to deplete T cells from heterogenous cell populations. 相似文献
10.