全文获取类型
收费全文 | 5260篇 |
免费 | 513篇 |
国内免费 | 209篇 |
专业分类
5982篇 |
出版年
2023年 | 48篇 |
2022年 | 119篇 |
2021年 | 191篇 |
2020年 | 126篇 |
2019年 | 143篇 |
2018年 | 150篇 |
2017年 | 93篇 |
2016年 | 171篇 |
2015年 | 277篇 |
2014年 | 292篇 |
2013年 | 356篇 |
2012年 | 388篇 |
2011年 | 379篇 |
2010年 | 244篇 |
2009年 | 203篇 |
2008年 | 258篇 |
2007年 | 228篇 |
2006年 | 246篇 |
2005年 | 187篇 |
2004年 | 202篇 |
2003年 | 150篇 |
2002年 | 129篇 |
2001年 | 106篇 |
2000年 | 107篇 |
1999年 | 97篇 |
1998年 | 41篇 |
1997年 | 43篇 |
1996年 | 41篇 |
1995年 | 37篇 |
1994年 | 44篇 |
1993年 | 41篇 |
1992年 | 66篇 |
1991年 | 74篇 |
1990年 | 47篇 |
1989年 | 57篇 |
1988年 | 57篇 |
1987年 | 55篇 |
1986年 | 46篇 |
1985年 | 55篇 |
1984年 | 43篇 |
1983年 | 31篇 |
1982年 | 23篇 |
1981年 | 20篇 |
1979年 | 31篇 |
1978年 | 23篇 |
1977年 | 20篇 |
1975年 | 21篇 |
1974年 | 22篇 |
1973年 | 25篇 |
1971年 | 17篇 |
排序方式: 共有5982条查询结果,搜索用时 15 毫秒
191.
Cheng Chu Gang Xu Xiaocong Li Zuowei Duan Lihong Tao Hongxia Cai Ming Yang Xinjiang Zhang Bin Chen Yanyu Zheng Hongcan Shi Xiaoyu Li 《Journal of cellular and molecular medicine》2021,25(1):110-119
Shear stress was reported to regulate the expression of AC007362, but its underlying mechanisms remain to be explored. In this study, to isolate endothelial cells of blood vessels, unruptured and ruptured intracranial aneurysm (IA) tissues were collected from IA patients. Subsequently, quantitative real-time PCR (qRT-PCR), Western blot and luciferase assay were performed to investigate the relationships between AC007362, miRNAs-493 and monocyte chemoattractant protein-1 (MCP-1) in human umbilical vein endothelial cells (HUVECs) exposed to shear stress. Reduced representation bisulphite sequencing (RRBS) was performed to assess the level of DNA methylation in AC007362 promoter. Accordingly, AC007362 and MCP-1 were significantly up-regulated while miR-493 was significantly down-regulated in HUVECs exposed to shear stress. AC007362 could suppress the miR-493 expression and elevate the MCP-1 expression, and miR-493 was shown to respectively target AC007362 and MCP-1. Moreover, shear stress in HUVECs led to the down-regulated DNA methyltransferase 1 (DNMT1), as well as the decreased DNA methylation level of AC007362 promoter. Similar results were also observed in ruptured IA tissues when compared with unruptured IA tissues. In conclusion, this study presented a deep insight into the operation of the regulatory network of AC007362, miR-493 and MCP-1 upon shear stress. Under shear stress, the expression of AC007362 was enhanced by the inhibited promoter DNA methylation, while the expression of MCP-1 was enhanced by sponging the expression of miR-493. 相似文献
192.
Ng Chu Xin Le Cheng Foh Tor Yin Sim Lee Sau Har 《International journal of peptide research and therapeutics》2021,27(4):2757-2775
International Journal of Peptide Research and Therapeutics - Bioactive peptides have emerged as promising therapeutic alternatives in pharmaceutical industry, especially to fight cancer. Here we... 相似文献
193.
Ecosystems - In arid environments, shade provided by vegetation forms the crux of many facilitation pathways by providing other organisms with relief from high levels of solar radiation and extreme... 相似文献
194.
溪流鱼类多样性沿着河流纵向梯度的空间分布规律已得到大量报道, 但这些研究大多聚焦基于物种组成的分类α多样性, 而有关分类β多样性和功能多样性的纵向梯度分布规律及其对人类干扰的响应研究较少。本文以青弋江上游3条人为干扰程度不同的河源溪流为研究区域, 比较研究了人为干扰对溪流鱼类功能α和β多样性及其纵向梯度分布格局的影响。结果显示, 人类干扰改变了河源溪流鱼类功能多样性的纵向梯度格局——由线性变化变为二项式分布。此外, 我们发现, 人为干扰导致土著种被本地入侵种取代, 且较强的土地利用和水污染排放可能增大环境的不连续性, 而群落周转和嵌套变化往往取决于环境的变化。尽管功能β多样性由嵌套成分主导, 但周转成分占比相对于人为干扰较小的溪流而言明显增加。人为干扰显著改变了受干扰溪流鱼类的物种组成和功能多样性, 且功能多样性的纵向梯度格局在不同的多样性指标上存在差异。本研究强调, 在评估人为干扰下多样性的变化时, 需要从多方面考虑, 包括空间尺度和多样性指标等。 相似文献
195.
Xiaoqian Liu Yuanfeng Zhang Kaimin Li Yinghui Liu Junqing Xu Junjie Ma Licai An Hui Wang Xiaoxia Chu 《Translational oncology》2021,14(7):101085
Refractory/relapsed B cell lymphoma patients who received the available anti-CD19 chimeric antigen receptor (CAR) T cells may still experience a short duration of remission. Here in this study, we evaluated the safety and efficacy of a novel dominant-negative programmed cell death-1 (PD-1) armored anti-CD19 CAR T cells. A total of 9 patients (including 4 diffuse large B cell lymphomas, DLBCL, 2 transformed follicular lymphomas, TFL, and 3 follicular lymphomas, FL) received the novel CAR T cells infusion at a dose of more than 1 × 106/kg. Grade ≥ 3 cytokine release syndrome (CRS) and neurotoxicity were observed in 11.1% (n = 1/9) and 11.1% (n = 1/9) of patients, respectively. The overall response rate (ORR) was 77.8% (n = 7/9) and complete response (CR) rate was 55.6% (n = 5/9). Two patients have ongoing CR (all at 20+ months). CAR T cells expanded after infusion and continued to be detectable at 12+ months in patients with ongoing CR. This novel CD19-CAR T cell was safe and effective with durable remissions in patients with refractory/relapsed B cell lymphoma. 相似文献
196.
197.
198.
Katherine T. Bliss Miensheng Chu Colin M. Jones-Weinert Carol C. Gregorio 《Molecular biology of the cell》2013,24(7):995-1006
Focal adhesions are intricate protein complexes that facilitate cell attachment, migration, and cellular communication. Lasp-2 (LIM-nebulette), a member of the nebulin family of actin-binding proteins, is a newly identified component of these complexes. To gain further insights into the functional role of lasp-2, we identified two additional binding partners of lasp-2: the integral focal adhesion proteins vinculin and paxillin. Of interest, the interaction of lasp-2 with its binding partners vinculin and paxillin is significantly reduced in the presence of lasp-1, another nebulin family member. The presence of lasp-2 appears to enhance the interaction of vinculin and paxillin with each other; however, as with the interaction of lasp-2 with vinculin or paxillin, this effect is greatly diminished in the presence of excess lasp-1. This suggests that the interplay between lasp-2 and lasp-1 could be an adhesion regulatory mechanism. Lasp-2’s potential role in metastasis is revealed, as overexpression of lasp-2 in either SW620 or PC-3B1 cells—metastatic cancer cell lines—increases cell migration but impedes cell invasion, suggesting that the enhanced interaction of vinculin and paxillin may functionally destabilize focal adhesion composition. Taken together, these data suggest that lasp-2 has an important role in coordinating and regulating the composition and dynamics of focal adhesions. 相似文献
199.
The shrimp Penaeus chinensis at moult stage Do were subjected to one of the three following treatments: bilateral eyestalk ablation, amputation of the fifth pair of pereiopods, and both of the above treatments. Two consecutive ecdyses after treatments were followed. Intact animals served as control. Precocious moulting was exhibited in all treated groups. Eyestalk ablation shortened the time to the first ecdysis more than does limb amputation. Additive effect was found in shrimps receiving both treatments. The duration between the first and second ecdyses in treated shrimps was shorter than that of intact animals, but the durations in the three treated groups were not significantly different from one another. Regenerates of limbs appeared after the second ecdysis following limb amputation. Further, change of body colour from black and green to red and white was observed in shrimps with eyestalk ablation. 相似文献
200.
Alan Chu 《Computer methods in biomechanics and biomedical engineering》2013,16(6):795-802
Computational models of the musculoskeletal system are prone to design errors. It is possible to create a model that cannot satisfy equilibrium conditions for a set of external loading conditions. A model is ‘loadable’ if there exists a set of muscle forces that can resist an arbitrary applied force within a prescribed range. In this study, a novel mathematical method is introduced to determine whether models are loadable. In addition, an idealised musculoskeletal model is presented in order to develop the theory behind the mathematical method. The method uses the simplex algorithm to determine feasibility of the linear programming problem and can determine loadability for an arbitrary, continuous range of external forces. The method was applied to a three-dimensional model of the shoulder and correctly determined loadability for a range of externally applied forces. 相似文献