全文获取类型
收费全文 | 9351篇 |
免费 | 866篇 |
国内免费 | 1217篇 |
出版年
2024年 | 25篇 |
2023年 | 100篇 |
2022年 | 250篇 |
2021年 | 361篇 |
2020年 | 297篇 |
2019年 | 371篇 |
2018年 | 327篇 |
2017年 | 262篇 |
2016年 | 335篇 |
2015年 | 544篇 |
2014年 | 647篇 |
2013年 | 693篇 |
2012年 | 904篇 |
2011年 | 819篇 |
2010年 | 542篇 |
2009年 | 527篇 |
2008年 | 573篇 |
2007年 | 507篇 |
2006年 | 436篇 |
2005年 | 417篇 |
2004年 | 326篇 |
2003年 | 301篇 |
2002年 | 294篇 |
2001年 | 168篇 |
2000年 | 166篇 |
1999年 | 119篇 |
1998年 | 117篇 |
1997年 | 68篇 |
1996年 | 76篇 |
1995年 | 79篇 |
1994年 | 67篇 |
1993年 | 54篇 |
1992年 | 62篇 |
1991年 | 48篇 |
1990年 | 51篇 |
1989年 | 43篇 |
1988年 | 47篇 |
1987年 | 39篇 |
1986年 | 31篇 |
1985年 | 36篇 |
1984年 | 31篇 |
1983年 | 26篇 |
1982年 | 26篇 |
1981年 | 18篇 |
1980年 | 14篇 |
1979年 | 18篇 |
1977年 | 16篇 |
1974年 | 16篇 |
1972年 | 16篇 |
1971年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 515 毫秒
991.
Juanfang Liu Xiaodong Yan Ling Li Yi Zhu Kefeng Qin Linfu Zhou Dong Sun Xiaohui Zhang Ruidong Ye Gang Zhao 《Neurochemical research》2012,37(12):2738-2747
Alzheimer??s disease is a neurodegenerative disease characterized by the production of ??-amyloid proteins and hyperphosphorylation of tau protein. Inflammation and apoptotic severity were highly correlated with earlier age at onset of Alzheimer??s disease and were also associated with cognitive decline. This study aims to examine whether the traditional Chinese medicine ginsennoside Rd could prevent cognitive deficit and take neuroprotective effects in ??-amyloid peptide 1?C40-induced rat model of Alzheimer??s disease. To produce Alzheimer??s disease animal model, aggregated ??-amyloid peptide 1?C40 injected into hippocampus bilaterally. Ginsennoside Rd protected their cognitive impairment and improved their memory function by daily intraperitoneal injection for 30?days consecutively. In addition, ginsennoside Rd alleviated the inflammation induced by ??-amyloid peptide 1?C40. Furthermore, ginsennoside Rd played a role in the down-regulation of caspase-3 proteins and reduced the apoptosis that normally followed ??-amyloid peptide 1?C40 injection. The results of this study showed that the pretreatment of ginsennoside Rd had neuroprotective effects in ??-amyloid peptide 1?C40-induced AD model rat. 相似文献
992.
Dystrophin (DMD) gene is the largest gene containing 79 exons involving various mutation types and regions, and targeted next-generation sequencing (NGS) was employed in detecting DMD gene mutation in the present study. A literature-annotated disease nonsense mutation (c.10141C>T, NM_004006.1) in exon 70 that has been reported as Duchenne Muscular Dystrophy (DMD)-causing mutation was found in our two patients, the proband and his cousin. In the present study two main methods were used, the next-generation sequencing and the classic Sanger sequencing. The exon capture followed by HiSeq2000 sequencing was specifically used in this study. Combined applications of the next-generation sequencing platform and bioinformatics are proved to be effective methods for DMD diagnosis. 相似文献
993.
The present study investigated the expression of the apoptosis-related genes fas-associated via death domain (FADD) and Bcl-2 in the endometrium during the window of implantation in polycystic ovary syndrome (PCOS) patients. The aim was to explore the role of cell apoptosis in endometrial receptivity during this period. The subjects were divided into experimental and control group. The experimental group comprised 12 infertile women with PCOS, and the control group comprised 12 women who were infertile because of tubal pathological factors but had normal menstrual cycles. Endometria were collected by biopsy 7d after ovulation. Six samples from each group were randomly selected and subjected to gene chip analyses. The expression of endometrial FADD and Bcl-2 was determined by immunohistochemistry, and cell apoptosis was detected by the TUNEL method. Compared with the control group, 194 differentially expressed genes were found in the PCOS group, 102 of which were upregulated and 92 were downregulated. The differentially expressed genes were divided into 15 types according to function. Among the nine genes related to cell apoptosis, five (including Bcl-2) were upregulated and four were downregulated (including FADD). Bcl-2 expression during the window of implantation in the PCOS group increased compared with the control group, showing a significant difference (P<0.05). FADD expression in the PCOS group notably decreased compared with that in the control group, which also showed a significant difference (P<0.05). Cell apoptosis analysis showed a significant difference between the average apoptotic indices in the PCOS and control groups (P<0.05). Significant differences were observed between the endometrial gene expression in the PCOS and control groups. The decrease in cell apoptosis during the window of implantation in PCOS patients may be one of the causes of the reduced endometrial receptivity. 相似文献
994.
995.
Han X Wang Y Liu X Jiang L Ren Y Liu F Peng C Li J Jin X Wu F Wang J Guo X Zhang X Cheng Z Wan J 《Journal of experimental botany》2012,63(1):121-130
The rice somaclonal mutant T3612 produces small grains with a floury endosperm, caused by the loose packing of starch granules. The positional cloning of the mutation revealed a deletion in a gene encoding a protein disulphide isomerase-like enzyme (PDIL1-1). In the wild type, PDIL1-1 was expressed throughout the plant, but most intensely in the developing grain. In T3612, its expression was abolished, resulting in a decrease in the activity of plastidial phosphorylase and pullulanase, and an increase in that of soluble starch synthase I and ADP-glucose pyrophosphorylase. The amylopectin in the T3612 endosperm showed an increase in chains with a degree of polymerization 8-13 compared with the wild type. The expression in the mutant's endosperm of certain endoplasmic reticulum stress-responsive genes was noticeably elevated. PDIL1-1 appears to play an important role in starch synthesis. Its absence is associated with endoplasmic reticulum stress in the endosperm, which is likely to underlie the formation of the floury endosperm in the T3612 mutant. 相似文献
996.
997.
998.
999.
L He K Naik S Meng J Cao AR Sidhaye A Ma S Radovick FE Wondisford 《The Journal of biological chemistry》2012,287(38):32069-32077
A major cause of fasting hyperglycemia in diabetes mellitus is unregulated hepatic glucose production (HGP). Insulin suppresses HGP by phosphorylating CBP and disassembling the CREB-CBP complex from gluconeogenic genes. p300 is closely related to CBP; but in contrast to CBP, p300 binds constitutively to CREB due to the absence of phosphorylation site found in CBP. In a phosphorylation-competent p300(G442S) knock-in mouse model, we demonstrate that HGP is now exquisitely sensitive to insulin suppression. p300(G422S) and hepatic-deleted p300 mice exhibited significant lower blood glucose levels in the fasted and post-prandial states, indicating a role for p300 in maintaining basal HGP. 相似文献
1000.
Mu S Tian X Ruan Y Liu Y Bian D Ma C Yu C Feng M Wang F Gao L Zhao JJ 《Biochemical and biophysical research communications》2012,418(2):347-352
Insulin-like growth factor-1 (IGF-1) is a growth factor of the thyroid that has been shown in our previous study to possess proliferative and antiapoptotic effects in FRTL-5 cell lines through the upregulation of cyclin D and Fas-associated death domain-like interleukin-1-converting enzyme (FLICE)-inhibitory protein (FLIP). Diosgenin, a natural steroid sapogenin from plants, has been shown to induce apoptosis in many cell lines, with the exception of thyroid cells. In this report, we investigated the apoptotic effect and mechanism of diosgenin in IGF-1-stimulated primary human thyrocytes. Primary human thyrocytes were preincubated with or without IGF-1 for 24h and subsequently exposed to varying concentrations of diosgenin for different times. We found that diosgenin induced apoptosis in human thyrocytes pretreated with IGF-1 in a dose-dependent manner through the activation of caspase cascades. Moreover, diosgenin inhibited FLIP and activated caspase-8 in the FAS-related apoptotic pathway. Diosgenin increased the production of ROS, regulated the balance of Bax and Bcl-2 and cleaved caspase-9 in the mitochondrial apoptotic pathway. These results indicate that diosgenin induces apoptosis in IGF-1-stimulated primary human thyrocytes through two caspase-dependent pathways. 相似文献