全文获取类型
收费全文 | 5090篇 |
免费 | 330篇 |
国内免费 | 359篇 |
出版年
2024年 | 11篇 |
2023年 | 72篇 |
2022年 | 158篇 |
2021年 | 316篇 |
2020年 | 231篇 |
2019年 | 235篇 |
2018年 | 193篇 |
2017年 | 148篇 |
2016年 | 231篇 |
2015年 | 340篇 |
2014年 | 369篇 |
2013年 | 375篇 |
2012年 | 514篇 |
2011年 | 412篇 |
2010年 | 242篇 |
2009年 | 235篇 |
2008年 | 245篇 |
2007年 | 197篇 |
2006年 | 182篇 |
2005年 | 145篇 |
2004年 | 111篇 |
2003年 | 102篇 |
2002年 | 104篇 |
2001年 | 85篇 |
2000年 | 77篇 |
1999年 | 72篇 |
1998年 | 42篇 |
1997年 | 42篇 |
1996年 | 38篇 |
1995年 | 44篇 |
1994年 | 39篇 |
1993年 | 24篇 |
1992年 | 31篇 |
1991年 | 33篇 |
1990年 | 17篇 |
1989年 | 16篇 |
1988年 | 12篇 |
1987年 | 10篇 |
1986年 | 7篇 |
1985年 | 10篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1965年 | 1篇 |
排序方式: 共有5779条查询结果,搜索用时 296 毫秒
971.
Mike Ran Zou Jian Cao Zongzhi Liu Sung Jin Huh Kornelia Polyak Qin Yan 《The Journal of biological chemistry》2014,289(25):17620-17633
The JmjC domain-containing H3K4 histone demethylase jumonji AT-rich interactive domain 1B (JARID1B) (also known as KDM5B and PLU1) is overexpressed in breast cancer and is a potential target for breast cancer treatment. To investigate the in vivo function of JARID1B, we developed Jarid1b−/− mice and characterized their phenotypes in detail. Unlike previously reported Jarid1b−/− strains, the majority of these Jarid1b−/− mice were viable beyond embryonic and neonatal stages. This allowed us to further examine phenotypes associated with the loss of JARID1B in pubertal development and pregnancy. These Jarid1b−/− mice exhibited decreased body weight, premature mortality, decreased female fertility, and delayed mammary gland development. Related to these phenotypes, JARID1B loss decreased serum estrogen level and reduced mammary epithelial cell proliferation in early puberty. In mammary epithelial cells, JARID1B loss diminished the expression of key regulators for mammary morphogenesis and luminal lineage specification, including FOXA1 and estrogen receptor α. Mechanistically, JARID1B was required for GATA3 recruitment to the Foxa1 promoter to activate Foxa1 expression. These results indicate that JARID1B positively regulates mammary ductal development through both extrinsic and cell-autonomous mechanisms. 相似文献
972.
973.
974.
Qi Cao Kexin Zhao Xi Zo? Zhong Yuanjie Zou Haichuan Yu Peng Huang Tian-Le Xu Xian-Ping Dong 《The Journal of biological chemistry》2014,289(33):23189-23199
Lysosomes contain abundant ATP, which is released through lysosomal exocytosis following exposure to various stimuli. However, the molecular mechanisms underlying lysosomal ATP accumulation remain unknown. The vesicular nucleotide transporter, also known as solute carrier family 17 member 9 (SLC17A9), has been shown to function in ATP transport across secretory vesicles/granules membrane in adrenal chromaffin cells, T cells, and pancreatic cells. Here, using mammalian cell lines, we report that SLC17A9 is highly enriched in lysosomes and functions as an ATP transporter in those organelles. SLC17A9 deficiency reduced lysosome ATP accumulation and compromised lysosome function, resulting in cell death. Our data suggest that SLC17A9 activity mediates lysosomal ATP accumulation and plays an important role in lysosomal physiology and cell viability. 相似文献
975.
Yuan Zhang Wei Zou Fenggong Cui Nan Wang Dongyan Zhang Yuying Cui Peng Liu Jing Liu 《The Journal of membrane biology》2014,247(1):73-80
The absorption of phospholipid may improve the fluidity of membrane and enzyme activities. Phospholipids also play a role in promoting Caveolae formation and membrane synthesis. Caveolin-1 has a significant effect on signaling pathways involved in regulating cell proliferation and stress responsiveness. Thus, we can speculate that Caveolin-1 could affect the sense of environmental stress. We use Chang liver cell line to investigate the ability of Caveolin-1 to modulate the cellular response to ethanol injury. Caveolin-1 downregulate cells (Cav-1?/?) were established by stable transfecting with psiRNA-CAV1 plasmids, which were more sensitive to toxic effects of ethanol than the untransfected parental cells (WT). Releasing of ALT and electric conductivity were changed significantly in Cav-1?/? cells compared with WT. Caveolin-1 gene silencing could obviously down-regulate the activities of protein kinase C-α (PKC-α) and phospho-p42/44 MAP kinase, indicating cell proliferation and self-repairing abilities were inhibited. However, the levels of Caveolin-1 and PKC-α were increased by phosphatidylcholine administration. The results indicated that the inhibition of lipid peroxidation by phosphatidylcholine could lead to the prevention of membrane disruption, which closely correlated with the level of Caveolin-1. Since the protective effects of phosphatidylcholine against ethanol-induced lipid peroxidation might be regulated by phospholipid-PKC-α signaling pathway, related with Caveolin-1, the potential effects of phosphatidylcholine on membranes need to be verified. 相似文献
976.
Rongcheng Zhang Yuhui Zhang Jian Zhang Tao An Yan Huang Xiao Guo James L. Januzzi Thomas P. Cappola Shijie Yin Yunhong Wang Qiong Zhou Changhong Zou Shiming Ji Rong Lv 《PloS one》2014,9(10)
Background
sST2 has been shown to be a risk predictor in heart failure (HF). Our aim was to explore the characteristics and prognostic value of soluble ST2 (sST2) in hospitalized Chinese patients with HF.Methods and Results
We consecutively enrolled 1528 hospitalized patients with HF. Receiver operating characteristic (ROC) and multivariable Cox proportional hazards analysis were used to assess the prognostic values of sST2. Adverse events were defined as all-cause death and cardiac transplantation. During a median follow-up of 19.1 months, 325 patients experienced adverse events. Compared with patients free of events, sST2 concentrations were significantly higher in patients with events (P<0.001). Univariable and multivariable Cox regression analyses showed sST2 concentrations were significantly associated with adverse events (per 1 log unit, adjusted hazard ratio 1.52, 95% confidence interval: 1.30 to 1.78, P<0.001). An sST2 concentration in the highest quartiles (>55.6 ng/mL) independently predicted events in comparison to the lowest quartile (≤25.2 ng/mL) when adjusted by multivariable model. In ROC analysis, the area under the curve for sST2 was not different from that for NT-proBNP in short and longer term. Over time, sST2 also improved discrimination and reclassification of risk beyond NT-proBNP.Conclusions
sST2 is a strong independent risk predictor in Chinese patients hospitalized with HF and can significantly provide additional prognostic value to NT-proBNP in risk prediction. 相似文献977.
If equipped with several radar emitters, a target will produce more than one measurement per time step and is denoted as an extended target. However, due to the requirement of all possible measurement set partitions, the exact probability hypothesis density filter for extended target tracking is computationally intractable. To reduce the computational burden, a fast partitioning algorithm based on hierarchy clustering is proposed in this paper. It combines the two most similar cells to obtain new partitions step by step. The pseudo-likelihoods in the Gaussian-mixture probability hypothesis density filter can then be computed iteratively. Furthermore, considering the additional measurement information from the emitter target, the signal feature is also used in partitioning the measurement set to improve the tracking performance. The simulation results show that the proposed method can perform better with lower computational complexity in scenarios with different clutter densities. 相似文献
978.
979.
Deep phylogeographic divergence of a migratory passerine in Sino‐Himalayan and Siberian forests: the Red‐flanked Bluetail (Tarsiger cyanurus) complex 下载免费PDF全文
Qing Chang Yang Liu Xiaojun Yang Zhengwang Zhang Min Zhang Qiang Zhang Fasheng Zou 《Ecology and evolution》2014,4(7):977-986
Enormous mountainous forests in Sino‐Himalayans and Siberia harbor important avian biodiversity in the Northern Hemisphere. Numerous studies in last two decades have been contributed to systematics and taxonomy of passerines birds in these regions and have revealed various and complex phylogeographic patterns. A passerine species Red‐flanked Bluetail Tarsiger cyanurus provided a good system to manifest such evolutionary complexity. The subspecies T. c. cyanurus and T. c. rufilatus (or/and T. c. pallidior), divergent in morphology, acoustics, and migratory strategies are allopatric in Siberia and Sino‐Himalayan forests, respectively. The two taxa most likely deserve full species status but rigorous genetic analysis is missing. In this study, multilocus phylogeography based on mitochondrial DNA and Z‐linked DNA reveals that T. c. cyanurus and T. c. rufilatus are reciprocally monophyletic with significant statistical support and differ with a large number of diagnostic nucleotide sites resulting substantial genetic divergence. Our finding supports the proposed split of Tarsiger cyanurus s.l. that T. cyanurus and T. rufilatus should be treated as two full species. Whether “pallidior” is a subspecies or geographical form of T. rufilatus is still uncertain. Additionally, these two forest passerine species may have diverged 1.88 (3.25–1.30) Mya, which might be shaped by geographical vicariance due to grassland and desert steppe on the central Loess Plateau during the Pliocene. Taken together, this study and further suggests another independent example of North Palearctic–Sino‐Himalayan phylogeographic pattern in Palearctic birds. 相似文献
980.