全文获取类型
收费全文 | 3413篇 |
免费 | 433篇 |
国内免费 | 5篇 |
专业分类
3851篇 |
出版年
2021年 | 42篇 |
2019年 | 36篇 |
2018年 | 40篇 |
2017年 | 43篇 |
2016年 | 50篇 |
2015年 | 107篇 |
2014年 | 132篇 |
2013年 | 134篇 |
2012年 | 174篇 |
2011年 | 174篇 |
2010年 | 109篇 |
2009年 | 88篇 |
2008年 | 140篇 |
2007年 | 136篇 |
2006年 | 141篇 |
2005年 | 125篇 |
2004年 | 128篇 |
2003年 | 123篇 |
2002年 | 132篇 |
2001年 | 79篇 |
2000年 | 90篇 |
1999年 | 80篇 |
1998年 | 49篇 |
1997年 | 29篇 |
1996年 | 37篇 |
1995年 | 41篇 |
1994年 | 38篇 |
1992年 | 74篇 |
1991年 | 62篇 |
1990年 | 64篇 |
1989年 | 47篇 |
1988年 | 51篇 |
1987年 | 62篇 |
1986年 | 47篇 |
1985年 | 60篇 |
1984年 | 55篇 |
1983年 | 44篇 |
1982年 | 38篇 |
1981年 | 29篇 |
1980年 | 37篇 |
1979年 | 56篇 |
1978年 | 29篇 |
1977年 | 45篇 |
1976年 | 33篇 |
1975年 | 30篇 |
1974年 | 45篇 |
1973年 | 41篇 |
1972年 | 31篇 |
1971年 | 28篇 |
1967年 | 34篇 |
排序方式: 共有3851条查询结果,搜索用时 0 毫秒
1.
2.
F Stephen Perry 《BMJ (Clinical research ed.)》1998,317(7156):481
3.
4.
Nataly Mancette Rijensky Netta R. Blondheim Shraga Eilon Barnea Nir Peled Eli Rosenbaum Aron Popovtzer Solomon M. Stemmer Alejandro Livoff Mark Shlapobersky Neta Moskovits Dafna Perry Eitan Rubin Itzhak Haviv Arie Admon 《Molecular & cellular proteomics : MCP》2020,19(8):1360-1374
Highlights
- •Sufficient tumor tissues are often unavailable large HLA peptidome discovery.
- •Using patient derived xenograft (PDX) tumors can overcome this limitation.
- •The large PDX HLA peptidomes expand significantly those of the original biopsies.
- •The HLA peptidomes of the PDX tumors included many tumor antigens.
5.
6.
The age-related loss of immune function, which is primarily due to loss of T-lymphocyte function, is also associated with accumulation in spleen lymphocytes of autofluorescent products indicative of peroxidation damage. In this study, we examined T-cell membranes for age-related changes which could be related to lipid peroxidation. Using fluorescence spectroscopy of CHCl3:CH3OH membrane extracts, we observed that old T-cells have a 2-fold greater accumulation of fluorescent products than old B-cells and that young T-cells, when exposed to free radicals in an in vitro system, accumulate significantly more fluorescent products over time than young B-cells. We used fluorescence polarization to show that young T-cell membranes are more fluid than young B-cell membranes. However, T-cell membrane fluidity decreases with age, whereas B-cell membrane fluidity does not change; in old mice, T-cell membranes are significantly less fluid than old B-cell membranes. Using two-dimensional electrophoresis, we showed that membrane extracts of old T-cells contain many more proteins than extracts of young T-cells. Our results indicate that age-related changes occur in T-cell membranes which could be due to their increased susceptibility to lipid peroxidation and these changes may contribute to the age-related decline in immune function. 相似文献
7.
8.
9.
M D Keppler M A Read P J Perry J O Trent T C Jenkins A P Reszka S Neidle K R Fox 《European journal of biochemistry》1999,263(3):817-825
We have used quantitative DNase I footprinting to measure the relative affinities of four disubstituted and two monosubstituted amidoanthraquinone compounds for intermolecular DNA triplexes, and have examined how the position of the attached base-functionalized substituents affects their ability to stabilize DNA triplexes. All four isomeric disubstituted derivatives examined stabilize DNA triplexes at micromolar or lower concentrations. Of the compounds studied the 2,7-disubstituted amidoanthraquinone displayed the greatest triplex affinity. The order of triplex affinity for the other disubstituted ligands decreases in the order 2,7 > 1,8 = 1,5 > 2,6, with the equivalent monosubstituted compounds being at least an order of magnitude less efficient. The 1,5-disubstituted derivative also shows some interaction with duplex DNA. These results have been confirmed by molecular modelling studies, which provide a rational basis for the structure-activity relationships. These suggest that, although all of the compounds bind through an intercalative mode, the 2,6, 2,7 and 1,5 disubstituted isomers bind with their two side groups occupying adjacent triplex grooves, in contrast with the 1,8 isomer which is positioned with both side groups in the same triplex groove. 相似文献
10.
A new index and four new graphical displays, termed "red–blue" plots, are presented to study and measure clustering in spatially referenced count data. The index can detect clusters in the form of patches, comprising several nearby large counts, and in the form of gaps, comprising several nearby small counts. The new methods quantify the degree to which the count for each sample unit contributes towards the overall degree of clustering, either as part of a patch or as a gap; provide tests of nonrandomness to detect clustering; and facilitate a comprehensive definition of the size and dimension of a cluster. The methods are illustrated using aphid field data. 相似文献