全文获取类型
收费全文 | 6980篇 |
免费 | 589篇 |
国内免费 | 1篇 |
出版年
2023年 | 45篇 |
2022年 | 108篇 |
2021年 | 202篇 |
2020年 | 84篇 |
2019年 | 116篇 |
2018年 | 168篇 |
2017年 | 140篇 |
2016年 | 214篇 |
2015年 | 343篇 |
2014年 | 353篇 |
2013年 | 485篇 |
2012年 | 582篇 |
2011年 | 522篇 |
2010年 | 334篇 |
2009年 | 259篇 |
2008年 | 396篇 |
2007年 | 369篇 |
2006年 | 343篇 |
2005年 | 330篇 |
2004年 | 296篇 |
2003年 | 276篇 |
2002年 | 287篇 |
2001年 | 85篇 |
2000年 | 63篇 |
1999年 | 80篇 |
1998年 | 66篇 |
1997年 | 65篇 |
1996年 | 36篇 |
1995年 | 47篇 |
1994年 | 44篇 |
1993年 | 53篇 |
1992年 | 64篇 |
1991年 | 47篇 |
1990年 | 52篇 |
1989年 | 54篇 |
1988年 | 35篇 |
1987年 | 33篇 |
1986年 | 46篇 |
1985年 | 45篇 |
1984年 | 42篇 |
1983年 | 26篇 |
1982年 | 36篇 |
1981年 | 30篇 |
1980年 | 21篇 |
1979年 | 31篇 |
1978年 | 22篇 |
1977年 | 24篇 |
1976年 | 30篇 |
1975年 | 27篇 |
1974年 | 26篇 |
排序方式: 共有7570条查询结果,搜索用时 15 毫秒
51.
Monica Gubersky D. M. P. Thomson Mark Lajzerowicz 《Cancer immunology, immunotherapy : CII》1986,21(2):107-113
Summary Human cancers express organ-specific cancer neoantigens (OSN) as determined by in vitro leukocyte responses to extracts of cancers by the tumor host. In this study, we determined whether the OSNs were normal developmental proteins that were expressed by fetal organs and re-expressed with oncogenesis. Fetal extracts, principally of lung and colon but also of liver and kidney, were tested for their ability to induce leukocyte adherence inhibition (LAI) as compared to extracts from adult tissues of the same organ. Leukocytes from lung cancer patients showed positive LAI responses to 13- and 19-week fetal lung tissue. Likewise, leukocytes from colon cancer patients showed positive LAI responses to 14- and 19-week fetal colon tissue, whereas leukocytes from control subjects did not. Neither group responded positively to 21-week fetal organs. Criss-cross experiments showed that the fetal antigen was organ specific. Multiparous pregnant women showed positive LAI responses to cancer extracts but not to extracts from normal tissues of the same organ. The pattern of the LAI response was bell-shaped. Positive LAI responses to lung and breast cancer were detected at 4 to 7 months gestation and peaked at 5 months. To the fetal colon, LAI positive responses were detected at 5 to 8 months gestation, with the peak response at 6 months. The results indicate that OSN of cancers are also expressed by fetal organs and sufficient antigen is shed by fetal organs to sensitize pregnant women. Older fetal organs (21 weeks) and adult organs do not express an immunogenic or antigenic OSN.Supported by a grant from the National Cancer Institute of Canada 相似文献
52.
53.
54.
55.
Peter L. Pingerelli Hiroshi Mizukami Monica J. Mooney Alice L. Schlaepfer 《The protein journal》1989,8(2):183-196
S100b is a calcium-binding protein that will bind to many calmodulin target molecules in a Ca2+-dependent manner. In order to study the Ca2+-dependent binding properties of S100b, its interaction with a calmodulin antagonist, trifluoperazine (TFP), was investigated using [19F]- and [1H]-NMR and UV-difference spectroscopy. It was estimated from [19F]-NMR that in the absence of Ca2+, thek 1/2 value of TFP was 130 µM, while itsk 1/2 value decreased to 28 µM in the presence of Ca2+. The addition of KCl was not antagonistic to the Ca2+-dependent interaction of TFP to S100b. The chemical exchange rate of TFP with Ca2+-bound S100b was estimated to be 9×102 sec?1. By comparison with TFP-calmodulin exchange rates, it is suggested that the TFP-binding site on S100b is structurally different from its binding sites on calmodulin. Proton NMR resonance broadening in the range 6.8–7.2 ppm, corresponding to phenylalanine nuclei of S100b, indicates that these residues may be involved in TFP binding. Addition of Ca2+ to a 1:1 mixture of S100b and TFP resulted in a red-shifted UV-difference spectrum, while no significant difference spectrum was detected when Mg2+ was added to a S100b-TFP solution. Thus, we suggest that Ca2+ induces the exposure of a hydrophobic domain on S100b containing one or more phenylalanine residues that will bind TFP but that this domain is different from the hydrophobic domain on calmodulin. 相似文献
56.
Clinical and biochemical studies in three patients with severe early infantile Cockayne syndrome 总被引:2,自引:0,他引:2
Jaak Jacken Helmut Klocker Helga Schwaiger Romuald Bellmann Monica Hirsch-Kauffmann Manfred Schweiger 《Human genetics》1989,83(4):339-346
Summary We present clinical and biochemical data from three patients with severe Cockayne syndrome (CS) of very early onset. Unlike in classic CS, signs became evident in the first weeks of life and led to unusually early death. Fibroblasts from two of the patients showed a complete defect of the repair of UV-induced thymine dimer lesions. They were unable to remove thymine dimer lesions from their DNA, had a severe reduction of the RNA synthesis rates after UV irradiation, and showed no reactivation of an UV-inactivated indicator gene and no DNA recondensation after UV irradiation. DNA repair investigated in these two fibroblast cell strains resembled that of xeroderma pigmentosum cells of complementation group A. In contrast, fibroblasts from the third patient showed the same in vitro repair characteristics as classic CS cells. 相似文献
57.
Copper uptake by free and immobilized cyanobacterium 总被引:1,自引:0,他引:1
Abstract Copper uptake in free and immobilized cells of the cyanobacterium Nostoc calcicola has been examined. The immobilized cells invariably maintained a higher profile of Cu intake rate (12.7 nmol mg−1 protein min−1 ) over the free cells (6.0 nmol mg−1 protein min−1 ). The total Cu uptake in immobilized cells was almost two and a half-times more than their free cell counterpart under identical experimental conditions. Also, the immobilized cells showed a stronger positive correlation between Cu adsorption and uptake. The results have been discussed in terms of improved metabolic efficiency of immobilized cells. 相似文献
58.
59.
60.
Functional antagonism between oncoprotein c-Jun and the glucocorticoid receptor 总被引:121,自引:0,他引:121
R Schüle P Rangarajan S Kliewer L J Ransone J Bolado N Yang I M Verma R M Evans 《Cell》1990,62(6):1217-1226