全文获取类型
收费全文 | 23563篇 |
免费 | 2178篇 |
国内免费 | 2151篇 |
出版年
2024年 | 22篇 |
2023年 | 351篇 |
2022年 | 463篇 |
2021年 | 1260篇 |
2020年 | 944篇 |
2019年 | 1167篇 |
2018年 | 1115篇 |
2017年 | 741篇 |
2016年 | 1058篇 |
2015年 | 1568篇 |
2014年 | 1807篇 |
2013年 | 1841篇 |
2012年 | 2261篇 |
2011年 | 1991篇 |
2010年 | 1206篇 |
2009年 | 1105篇 |
2008年 | 1278篇 |
2007年 | 1064篇 |
2006年 | 957篇 |
2005年 | 744篇 |
2004年 | 590篇 |
2003年 | 541篇 |
2002年 | 429篇 |
2001年 | 336篇 |
2000年 | 332篇 |
1999年 | 345篇 |
1998年 | 217篇 |
1997年 | 255篇 |
1996年 | 201篇 |
1995年 | 198篇 |
1994年 | 173篇 |
1993年 | 138篇 |
1992年 | 193篇 |
1991年 | 149篇 |
1990年 | 157篇 |
1989年 | 100篇 |
1988年 | 94篇 |
1987年 | 89篇 |
1986年 | 64篇 |
1985年 | 67篇 |
1984年 | 45篇 |
1983年 | 49篇 |
1982年 | 27篇 |
1981年 | 18篇 |
1980年 | 17篇 |
1979年 | 12篇 |
1978年 | 10篇 |
1969年 | 9篇 |
1968年 | 8篇 |
1965年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Honghong Yang Yuanyuan Zhang Zhihai Wang Shixun Zhong Guohua Hu Wenqi Zuo 《Bioelectromagnetics》2020,41(3):219-229
To investigate the possible mechanisms for biological effects of 1,800 MHz mobile radiofrequency radiation (RFR), the radiation-specific absorption rate was applied at 2 and 4 W/kg, and the exposure mode was 5 min on and 10 min off (conversation mode). Exposure time was 24 h short-term exposure. Following exposure, to detect cell DNA damage, cell apoptosis, and reactive oxygen species (ROS) generation, the Comet assay test, flow cytometry, DAPI (4′,6-diamidino-2-phenylindole dihydrochloride) staining, and a fluorescent probe were used, respectively. Our experiments revealed that mobile phone RFR did not cause DNA damage in marginal cells, and the rate of cell apoptosis did not increase (P > 0.05). However, the production of ROS in the 4 W/kg exposure group was greater than that in the control group (P < 0.05). In conclusion, these results suggest that mobile phone energy was insufficient to cause cell DNA damage and cell apoptosis following short-term exposure, but the cumulative effect of mobile phone radiation still requires further confirmation. Activation of the ROS system plays a significant role in the biological effects of RFR. Bioelectromagnetics. © 2020 The Authors. Bioelectromagnetics published by Wiley Periodicals, Inc. 相似文献
2.
3.
<正>Chemotherapy employs chemical substances to interfere with the growth of cancer cells,and is a major treatment strategy in human cancer including acute myeloid leukemia(AML).Although they often effectively kill fast-dividing tumor cells,chemotherapeutic drugs also profoundly affect 相似文献
4.
Yan Xue Liu Jia Wu Ke-Xin Yang Nan Pan Li-Ben Song Ying Liu Yang Tang Zhong-Hua 《Journal of Plant Growth Regulation》2022,41(6):2421-2434
Journal of Plant Growth Regulation - Early-spring plants are a special type of plant that complete their life cycle promptly in cold, early spring. Very little effort has been made into researching... 相似文献
5.
Fenglei Chen Yujing Wang Qinguang Liu Jiahui Hu Jiaqi Jin Zhiyu Ma Jinlong Zhang 《Journal of cellular physiology》2020,235(7-8):5666-5678
ER oxidoreduclin 1α (ERO1α) is an oxidase, participating in formation of secretory and membrane proteins. However, the other physiological functions ERO1α is not well known. We found that ERO1α is high in the Leydig cells of the testis. Therefore, the purposes of the current study are to explore the role of ERO1α and the possible mechanisms in regulating cell proliferation, apoptosis, and testosterone secretion of Leydig cells. ERO1α was mainly localized in Leydig cells in the adult mice testes by immunofluorescence staining. Western blot analysis showed that ERO1α was higher in Leydig cells than that in the seminiferous tubules. The effect of ERO1α on cell proliferation, apoptosis, and testosterone secretion was detected by transducing ERO1α overexpression and knockdown lentiviruses into cultured primary Leydig cells (PLCs) together with hCG exposure. Flow cytometry analysis showed that ERO1α promoted cell proliferation by increasing cell distribution at the S phase and decreasing that at the G0/G1 phase. Western bolt analysis showed that ERO1α increased CDK2 and CDK6 expression. Cell apoptosis determination found that ERO1α inhibited PLC apoptosis. Western bolt analysis showed that ERO1α increased the ratio of BCL-2/BAX, and decreased BAD and Caspase-3 expression. Enzyme-linked immunosorbent assay analysis demonstrated that ERO1α enhanced testosterone secretion. Western bolt analysis found that ERO1α increased StAR, 3β-HSD, and CYP17A1 expression. Furthermore, ERO1α could activate the PI3K/AKT/mTOR signaling pathway. In summary, these results suggest that ERO1α might play proliferation promotion and antiapoptotic roles and enhance testosterone secretion in PLC, at least partly, via activation of the PI3K/AKT/mTOR signaling pathway. 相似文献
6.
Focal adhesion kinase (FAK) functions as a key enzyme in the integrin-mediated adhesion-signalling pathway. Here, we aimed to investigate the effects of FAK on adhesion of human dental pulp (HDP) cells. We transfected lentiviral vectors to silence or overexpress FAK in HDP cells ex vivo. Early cell adhesion, cell survival and focal contacts (FCs)-related proteins (FAK and paxillin) were examined. By using immunofluorescence, the formation of FCs and cytoskeleton was detected, respectively. We found that both adhesion and survival of HDP cells were suppressed by FAK inhibition. However, FAK overexpression slightly inhibited cell adhesion and exhibited no change in cell survival compared with the control. A thick rim of cytoskeleton accumulated and smaller dot-shaped FCs appeared in FAK knockdown cells. Phosphorylation of paxillin (p-paxillin) was inhibited in FAK knockdown cells, verifying that the adhesion was inhibited. Less cytoskeleton and elongated FCs were observed in FAK-overexpressed cells. However, p-paxillin had no significant difference compared with the control. In conclusion, the data suggest that FAK maintains cell adhesion, survival and cytoskeleton formation, but excessive FAK has no positive effects on these aspects. 相似文献
7.
Jing Guo Xuezhu Ren Xiaohua Wang Zhiyong Qu Qianyun Zhou Chun Ran Xia Wang Juan Hu 《PloS one》2015,10(12)
The objective of this study was to examine rates of depression among migrant children (MC) and left-behind children (LBC) as compared to non-left-behind children (NLBC) and also to examine the relationship between depression among these children and the quality of their parent-child and teacher-child relationships. This study collected data from a large sample of 3,759 children aged from 8 to 17 years, including 824 who had been left behind by one parent (LBCO), 423 who had been left behind by both parents (LBCB), 568 MC and 1944 NLBC. Children’s Depression Inventory–Short Form was used to measure child depression. Parent-Child Relationship Scale (PCRS) and Teacher-Child Relationship Scale (TCRS) were used to measure the quality of parent-child and teacher-child relationships, respectively. The results showed that the prevalence of depression was 10.5% among NLBC, 13.1% among LBCO, 16.1% among LBCB, and 20.1% among MC. Depression was related to parent-child relationship quality and teacher-child relationship quality. Negative parent-child relationship was more relevant to depression than negative teacher-child relationship among LBCB, while negative teacher-child relationship was the most correlated with depression among MC. 相似文献
8.
The JAK/STAT signaling pathway plays important roles in vertebrate development and the regulation of complex cellular processes. Components of the pathway are conserved in Dictyostelium, Caenorhabditis, and Drosophila, yet the complete sequencing and annotation of the D. melanogaster and C. elegans genomes has failed to identify a receptor, raising the possibility that an alternative type of receptor exists for the invertebrate JAK/STAT pathway. Here we show that domeless (dome) codes for a transmembrane protein required for all JAK/STAT functions in the Drosophila embryo. This includes its known requirement for embryonic segmentation and a newly discovered function in trachea specification. The DOME protein has a similar extracellular structure to the vertebrate cytokine class I receptors, although its sequence has greatly diverged. Like many interleukin receptors, DOME has a cytokine binding homology module (CBM) and three extracellular fibronectin-type-III domains (FnIII). Despite its low degree of overall similarity, key amino acids required for signaling in the vertebrate cytokine class I receptors [3] are conserved in the CBM region. DOME is a signal-transducing receptor with most similarities to the IL-6 receptor family, but it also has characteristics found in the IL-3 receptor family. This suggests that the vertebrate families evolved from a single ancestral receptor that also gave rise to dome. 相似文献
9.
10.
Nan Cheng Chang Jin Ping Jin Dan Zhu Zuoxu Hou 《Journal of cellular and molecular medicine》2021,25(13):6137-6147
High glucose promoted expression of AKT3, a direct target gene of miR-29b, by regulating circHIPK3 that functioned as ceRNA to sponge and down-regulate miR-29b. As a potential target gene of miR-29b, AKT3 plays a crucial role in the pathogenesis of myocardial ischaemia/reperfusion (I/R) injury, and this study aimed to investigate the potential role of high glucose in the outcome of I/R injury. qPCR and luciferase assay were carried out to investigate the relationship between the expression of circHIPK3, miR-29b and ATK3 mRNA. Immunohistochemistry and TUNEL were performed to analyse the relationship between AKT3 expression and apoptosis of myocardiocytes in vivo. No obvious difference in myocardial functions was observed between I/R and control rats under hyperglycaemia (HG) and normal glucose (NG) conditions, except that the infarct size/area at risk (IS/AR) ratio and the amount of h-FABP expression were different under HG and NG conditions. The expression of circHIPK3 and ATK3 was significantly elevated in the rats preconditioned by NG, whereas the expression of miR-29a was remarkably decreased. Meanwhile, the apoptosis of myocardial tissue was reduced in the rats preconditioned by NG. Luciferase assay confirmed that miR-29a played a repressive role in the expression of circHIPK3 and ATK3. And subsequent study indicated that the over-expressed AKT3 could rescue the increased cell apoptosis rate induced by the knockdown of circHIPK3. In this study, we demonstrated that high glucose protects cardiomyocytes against I/R associated injury by suppressing apoptosis and high glucose promoted the expression of AKT3 by regulating the expression of circHIPK3/miR-29b. 相似文献