全文获取类型
收费全文 | 5536篇 |
免费 | 431篇 |
国内免费 | 339篇 |
专业分类
6306篇 |
出版年
2024年 | 6篇 |
2023年 | 65篇 |
2022年 | 147篇 |
2021年 | 259篇 |
2020年 | 178篇 |
2019年 | 212篇 |
2018年 | 193篇 |
2017年 | 139篇 |
2016年 | 214篇 |
2015年 | 345篇 |
2014年 | 397篇 |
2013年 | 422篇 |
2012年 | 511篇 |
2011年 | 451篇 |
2010年 | 280篇 |
2009年 | 254篇 |
2008年 | 282篇 |
2007年 | 250篇 |
2006年 | 204篇 |
2005年 | 186篇 |
2004年 | 171篇 |
2003年 | 129篇 |
2002年 | 113篇 |
2001年 | 109篇 |
2000年 | 99篇 |
1999年 | 99篇 |
1998年 | 41篇 |
1997年 | 51篇 |
1996年 | 42篇 |
1995年 | 40篇 |
1994年 | 29篇 |
1993年 | 33篇 |
1992年 | 41篇 |
1991年 | 39篇 |
1990年 | 46篇 |
1989年 | 36篇 |
1988年 | 23篇 |
1987年 | 24篇 |
1986年 | 13篇 |
1985年 | 14篇 |
1984年 | 10篇 |
1983年 | 10篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1979年 | 14篇 |
1978年 | 8篇 |
1973年 | 9篇 |
1972年 | 6篇 |
1971年 | 9篇 |
1968年 | 5篇 |
排序方式: 共有6306条查询结果,搜索用时 15 毫秒
81.
Tina L. Yuan Arnaud Amzallag Rachel Bagni Ming Yi Shervin Afghani William Burgan Nicole Fer Leslie A. Strathern Katie Powell Brian Smith Andrew M. Waters David Drubin Ty Thomson Rosy Liao Patricia Greninger Giovanna T. Stein Ellen Murchie Eliane Cortez Frank McCormick 《Cell reports》2018,22(7):1889-1902
82.
83.
Zhe Liu Kun Cao Zebin Liao Yuanyuan Chen Xiao Lei Qun Wei Cong Liu Xuejun Sun Yanyong Yang Jianming Cai Fu Gao 《Journal of cellular and molecular medicine》2020,24(7):3917-3930
Radiation protection on male testis is an important task for ionizing radiation-related workers or people who receive radiotherapy for tumours near the testicle. In recent years, Toll-like receptors (TLRs), especially TLR4, have been widely studied as a radiation protection target. In this study, we detected that a low-toxicity TLR4 agonist monophosphoryl lipid A (MPLA) produced obvious radiation protection effects on mice testis. We found that MPLA effectively alleviated testis structure damage and cell apoptosis induced by ionizing radiation (IR). However, as the expression abundance differs a lot in distinct cells and tissues, MPLA seemed not to directly activate TLR4 singling pathway in mice testis. Here, we demonstrated a brand new mechanism for MPLA producing radiation protection effects on testis. We observed a significant activation of TLR4 pathway in macrophages after MPLA stimulation and identified significant changes in macrophage-derived exosomes protein expression. We proved that after MPLA treatment, macrophage-derived exosomes played an important role in testis radiation protection, and specially, G-CSF and MIP-2 in exosomes are the core molecules in this protection effect. 相似文献
84.
85.
86.
TL Liao AC Lin E Chen TW Huang YM Liu YH Chang JF Lai TL Lauderdale JT Wang SC Chang SF Tsai YT Chen 《Journal of bacteriology》2012,194(19):5454
We report the complete genome sequence of Klebsiella oxytoca E718, a New Delhi metallo-β-lactamase-1 (NDM-1)-producing strain isolated from a renal transplant patient. The genome contains a 6,097,032-bp chromosome and two multidrug resistance plasmids with sizes of 324,906 bp and 110,781 bp. 相似文献
87.
88.
Garcinol (camboginol) is a polyisoprenylated benzophenone derivative isolated from fruit rind of Garcinia indica. This study was to elucidate the anti-oxidative and neuroprotective properties of garcinol in rat cortical neuron cultures. First, garcinol protects DNA from Fenton reaction-induced breakage in a dose-dependent manner, with an IC(50) value of 0.32 microM. Garcinol also inhibits xanthine oxidase activity with an IC(50) value of 52 microM and exhibits competitive inhibition. To further ascertain the neuroprotective effects of garcinol in inflammatory-mediated neurotoxicity, we utilized primary neuron/astrocyte co-cultures treated with LPS or cytokine. Our data implicate that treatment with garcinol (5 microM) for 7 days promotes neuronal attachment and neurite extension. The formation of nitric oxide (NO) by LPS in rat astrocytes has been suggested to correlate with the neurodegenerative process. In identifying the effect of neuroprotection, we found that garcinol prevented NO accumulation in LPS-treated astrocytes. Garcinol significantly reduced the expression of LPS-induced inflammatory mediators, such as iNOS and COX-2. Consequently, our results suggest that the neuroprotective effects of garcinol are associated with anti-oxidation and inhibition of iNOS induction in astrocytic cells. Garcinol may exert a similar anti-inflammatory effect and may be neuroprotective against brain injury. 相似文献
89.
目的 检测P13K、p-AKT及HIF-1α三种蛋白在胰腺癌组织中的表达并探讨其与临床病理因素的关系及三者之间的相关性.方法 采用免疫组织化学SP法检测43例胰腺癌组织、9例胰腺炎组织和8例正常胰腺组织中P13K、p-AKT及HIF.1a三种蛋白的表达.结果 P13K、p-AKT的阳性表达主要位于肿瘤细胞胞浆,HIF-1α的阳性表达主要位于细胞核或细胞浆.P13K、p-AKT及HIF-1α在胰腺癌组织中的阳性表达率分别为62.79%、67.44%和69.77%,三者均显著高于在正常胰腺组织和慢性胰腺炎组织中的表达,差异有统计学意义(P<0.01).P13K、p-AKT及HIF-1α的异常表达均与胰腺癌的淋巴结转移和TNM分期有关(P<0.05),与患者的性别、年龄、部位、分化程度和病理分型无关(P>0.05).P13K、p-AKT及HIF-1α三者间的表达呈正相关.结论 P13K、p-AKT及HIF-1α的表达在胰腺癌的生长、浸润转移中起重要作用,P13K-AKT信号通路激活可能促进HIF-1α的表达. 相似文献
90.
In large-scale heterogeneous cluster computing systems, processor and network failures are inevitable and can have an adverse effect on applications executing on such systems. One way of taking failures into account is to employ a reliable scheduling algorithm. However, most existing scheduling algorithms for precedence constrained tasks in heterogeneous systems only consider scheduling length, and not efficiently satisfy the reliability requirements of task. In recognition of this problem, we build an application reliability analysis model based on Weibull distribution, which can dynamically measure the reliability of task executing on heterogeneous cluster with arbitrary networks architectures. Then, we propose a reliability-driven earliest finish time with duplication scheduling algorithm (REFTD) which incorporates task reliability overhead into scheduling. Furthermore, to improve system reliability, it duplicates task as if task hazard rate is more than threshold \(\theta \) . The comparison study, based on both randomly generated graphs and the graphs of some real applications, shows that our scheduling algorithm can shorten schedule length and improve system reliability significantly. 相似文献