全文获取类型
收费全文 | 1044篇 |
免费 | 83篇 |
专业分类
1127篇 |
出版年
2022年 | 9篇 |
2021年 | 15篇 |
2020年 | 9篇 |
2019年 | 8篇 |
2018年 | 18篇 |
2017年 | 7篇 |
2016年 | 26篇 |
2015年 | 41篇 |
2014年 | 49篇 |
2013年 | 57篇 |
2012年 | 73篇 |
2011年 | 74篇 |
2010年 | 42篇 |
2009年 | 30篇 |
2008年 | 58篇 |
2007年 | 56篇 |
2006年 | 47篇 |
2005年 | 59篇 |
2004年 | 42篇 |
2003年 | 46篇 |
2002年 | 63篇 |
2001年 | 21篇 |
2000年 | 15篇 |
1999年 | 13篇 |
1998年 | 14篇 |
1997年 | 10篇 |
1996年 | 12篇 |
1995年 | 12篇 |
1994年 | 16篇 |
1993年 | 11篇 |
1992年 | 24篇 |
1991年 | 4篇 |
1990年 | 13篇 |
1989年 | 6篇 |
1988年 | 19篇 |
1987年 | 5篇 |
1986年 | 9篇 |
1985年 | 5篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1974年 | 6篇 |
1972年 | 3篇 |
1971年 | 5篇 |
1970年 | 3篇 |
排序方式: 共有1127条查询结果,搜索用时 15 毫秒
41.
Effects of electromagnetic field emitted by cellular phones on the EEG during an auditory memory task: a double blind replication study 总被引:5,自引:0,他引:5
Krause CM Haarala C Sillanmäki L Koivisto M Alanko K Revonsuo A Laine M Hämäläinen H 《Bioelectromagnetics》2004,25(1):33-40
The effects of electromagnetic fields (EMF) emitted by cellular phones on the event related desynchronization/synchronization (ERD/ERS) of the 4-6, 6-8, 8-10, and 10-12 Hz electroencephalogram (EEG) frequency bands were studied in 24 normal subjects performing an auditory memory task. This study was a systematic replication of our previous work. In the present double blind study, all subjects performed the memory task both with and without exposure to a digital 902 MHz field in a counterbalanced order. We were not able to replicate the findings from our earlier study. All eight of the significant changes in our earlier study were not significant in the present double blind replication. Also, the effect of EMF on the number of incorrect answers in the memory task was inconsistent. We previously reported no significant effect of EMF exposure on the number of incorrect answers in the memory task, but a significant increase in errors was observed in the present study. We conclude that EMF effects on the EEG and on the performance on memory tasks may be variable and not easily replicable for unknown reasons. 相似文献
42.
43.
44.
Rosas M Liddiard K Kimberg M Faro-Trindade I McDonald JU Williams DL Brown GD Taylor PR 《Journal of immunology (Baltimore, Md. : 1950)》2008,181(5):3549-3557
Dectin-1 is the archetypal signaling, non-Toll-like pattern recognition receptor that plays a protective role in immune defense to Candida albicans as the major leukocyte receptor for beta-glucans. Dectin-1-deficiency is associated with impaired recruitment of inflammatory leukocytes and inflammatory mediator production at the site of infection. In this study, we have used mice to define the mechanisms that regulate the dectin-1-mediated inflammatory responses. Myeloid cell activation by dectin-1 is controlled by inherent cellular programming, with distinct macrophage and dendritic cell populations responding differentially to the engagement of this receptor. The inflammatory response is further modulated by the progression of the phagocytosis, with "frustrated phagocytosis" resulting in dramatically augmented inflammatory responses. These studies demonstrate that dectin-1 in isolation is sufficient to drive a potent inflammatory response in a context-dependent manner. This has implications for the mechanism by which myeloid cells are activated during fungal infections and the processes involved in the therapeutic manipulation of the immune system via exogenous dectin-1 stimulation or blockade. 相似文献
45.
Our previous evidence suggests that heterogeneous nuclear ribonucleoprotein (hnRNP) A1 plays a part in the regulation of the Cyp2a5 gene by interacting with the 3' untranslated region (UTR) of the CYP2A5 mRNA. However, the exact role of this interaction is not clear. The aim of the present work was to gain further insight into the regulation process of Cyp2a5. For this purpose the 3' UTR of CYP2A5 was fused to the coding region of luciferase mRNA. Luciferase recombinants containing either the full length 3' UTR, or the 3' UTR lacking a previously described 71 nucleotide (nt) region (the hnRNP A1 primary binding site), were transiently expressed in cells expressing or lacking hnRNP A1. The expression of the luciferase recombinants was examined both at mRNA and enzyme activity levels. The results disclosed that the presence of hnRNP A1 was required for the high expression of the recombinant carrying the full length 3' UTR of CYP2A5. Deletion of the hnRNP A1 primary binding site dramatically modified the expression pattern: the mRNA levels and luciferase activities of the deletion mutant were independent from hnRNP A1. These results conclusively demonstrate that the 71 nt region in the 3' UTR of CYP2A5 mRNA can confer hnRNP A1-dependent regulation to a gene. In addition, comparison of RNA levels and luciferase activities suggested that regions flanking the hnRNP A1 binding site could regulate translation of the CYP2A5 mRNA. These results are consistent with a model in which the binding of hnRNP A1 to the 71 nt putative hairpin-loop region in the CYP2A5 mRNA 3' UTR upregulates mRNA levels possibly by protecting the mRNA from degradation. 相似文献
46.
Wu GH Auvinen A Yen AM Hakama M Walter SD Chen HH 《Biometrical journal. Biometrische Zeitschrift》2012,54(1):20-44
To compare the survival between screen-detected and clinically detected cancers, we applied a series of non-homogeneous stochastic processes to deal with leadtime, length bias, and over-detection by using full information on detection modes obtained from the Finnish randomized controlled trial for prostate cancer screening. The results show after 9-year follow-up the hazard ratio of prostate cancer death for screen-detected cases against clinically detected cases increased from 0.24 (95% CI: 0.16-0.35) without correction for these biases, to 0.76 after correction for leadtime and length biases, and finally to 1.03 (95% CI: 0.79-1.33) for a further adjustment for over-detection. Adjustment for leadtime and length bias but no over-detection led to a 24% reduction in prostate cancer death as a result of prostate-specific antigen test. The further calibration of over-detection indicates no gain in survival of screen-detected prostate cancers (excluding over-detected case as stayer considered in the mover-stayer model) as compared with the control group in the absence of screening that is considered as the mover. However, whether the model assumption on over-detection is robust should be validated with other data sets and longer follow-up. 相似文献
47.
48.
49.
Marius R. Robciuc Paulina Skrobuk Andrey Anisimov Vesa M. Olkkonen Kari Alitalo Robert H. Eckel Heikki A. Koistinen Matti Jauhiainen Christian Ehnholm 《PloS one》2012,7(10)
Peroxisome proliferator-activated receptor (PPAR) delta is an important regulator of fatty acid (FA) metabolism. Angiopoietin-like 4 (Angptl4), a multifunctional protein, is one of the major targets of PPAR delta in skeletal muscle cells. Here we investigated the regulation of Angptl4 and its role in mediating PPAR delta functions using human, rat and mouse myotubes. Expression of Angptl4 was upregulated during myotubes differentiation and by oleic acid, insulin and PPAR delta agonist . Treatment with GW501516 or Angptl4 overexpression inhibited both lipoprotein lipase (LPL) activity and LPL-dependent uptake of FAs whereas uptake of BSA-bound FAs was not affected by either treatment. Activation of retinoic X receptor (RXR), PPAR delta functional partner, using bexarotene upregulated Angptl4 expression and inhibited LPL activity in a PPAR delta dependent fashion. Silencing of Angptl4 blocked the effect of GW501516 and bexarotene on LPL activity. Treatment with GW501516 but not Angptl4 overexpression significantly increased palmitate oxidation. Furthermore, Angptl4 overexpression did not affect the capacity of GW501516 to increase palmitate oxidation. Basal and insulin stimulated glucose uptake, glycogen synthesis and glucose oxidation were not significantly modulated by Angptl4 overexpression. Our findings suggest that FAs-PPARdelta/RXR-Angptl4 axis controls the LPL-dependent uptake of FAs in myotubes, whereas the effect of PPAR delta activation on beta-oxidation is independent of Angptl4. GW501516相似文献
50.
M. Johansson H. Ellegren L. Marklund W. Coppieters L. Andersson 《Mammalian genome》1994,5(12):785-790
Linkage maps of porcine Chromosomes (Chrs) 3, 6, and 9, based on 31 polymorphic markers, are reported. The markers include 14 microsatellites, 12 RFLPs, three protein polymorphisms, and two blood group loci. The genetic interpretations of 11 RFLPs are documented. The markers were scored in a three-generation Wild Boar/Large White pedigree, and genetic maps were constructed on the basis of two-point and multi-point linkage analysis. Altogether the maps span a genetic distance of 216 cM, and previous physical assignments indicate that the linkage groups cover major parts of the three chromosomes. Significant differences in recombination rates between the sexes were observed for all three chromosomes. The recombination rate on the q arm of Chr 6 was markedly low. Sixteen loci are informative with regard to comparative mapping, that is, they have previously been mapped in the human and/or mouse genomes. 相似文献