全文获取类型
收费全文 | 103937篇 |
免费 | 9816篇 |
国内免费 | 7215篇 |
学科分类
工业技术 | 120968篇 |
出版年
2024年 | 179篇 |
2023年 | 1684篇 |
2022年 | 2110篇 |
2021年 | 4954篇 |
2020年 | 3170篇 |
2019年 | 2878篇 |
2018年 | 2640篇 |
2017年 | 3354篇 |
2016年 | 3793篇 |
2015年 | 3955篇 |
2014年 | 5618篇 |
2013年 | 6042篇 |
2012年 | 6955篇 |
2011年 | 8609篇 |
2010年 | 6368篇 |
2009年 | 7083篇 |
2008年 | 6330篇 |
2007年 | 7058篇 |
2006年 | 6410篇 |
2005年 | 5460篇 |
2004年 | 4383篇 |
2003年 | 3861篇 |
2002年 | 3100篇 |
2001年 | 2305篇 |
2000年 | 2177篇 |
1999年 | 1820篇 |
1998年 | 1422篇 |
1997年 | 1184篇 |
1996年 | 1010篇 |
1995年 | 929篇 |
1994年 | 860篇 |
1993年 | 636篇 |
1992年 | 509篇 |
1991年 | 425篇 |
1990年 | 331篇 |
1989年 | 262篇 |
1988年 | 185篇 |
1987年 | 144篇 |
1986年 | 157篇 |
1985年 | 95篇 |
1984年 | 91篇 |
1983年 | 57篇 |
1982年 | 77篇 |
1981年 | 53篇 |
1980年 | 60篇 |
1979年 | 49篇 |
1978年 | 21篇 |
1977年 | 29篇 |
1976年 | 27篇 |
1975年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
31.
为了解破碎围岩分别采用锚杆支护、锚喷支护以及锚喷+锚索耦合三种支护方式下的支护效果,进而为破碎围岩巷道选择合理的支护方式提供参考。通过借助FLAC3D软件建立数值模型,分析不同支护条件下的破碎围岩巷道位移量、应力分布以及塑性区的时空演化特征。结果表明,采用锚喷+锚索耦合支护时,可以较好的控制巷道围岩的位移量、减小应力集中效应、缩小塑性区的影响范围。 相似文献
32.
33.
34.
Cheng-Chin Huang Ching-Yao Yang Chin-Chuan Su Kai-Min Fang Cheng-Chieh Yen Ching-Ting Lin Jui-Min Liu Kuan-I Lee Ya-Wen Chen Shing-Hwa Liu Chun-Fa Huang 《International journal of molecular sciences》2021,22(9)
4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP), a major active metabolite of bisphenol A (BPA), is generated in the mammalian liver. Some studies have suggested that MBP exerts greater toxicity than BPA. However, the mechanism underlying MBP-induced pancreatic β-cell cytotoxicity remains largely unclear. This study demonstrated the cytotoxicity of MBP in pancreatic β-cells and elucidated the cellular mechanism involved in MBP-induced β-cell death. Our results showed that MBP exposure significantly reduced cell viability, caused insulin secretion dysfunction, and induced apoptotic events including increased caspase-3 activity and the expression of active forms of caspase-3/-7/-9 and PARP protein. In addition, MBP triggered endoplasmic reticulum (ER) stress, as indicated by the upregulation of GRP 78, CHOP, and cleaved caspase-12 proteins. Pretreatment with 4-phenylbutyric acid (4-PBA; a pharmacological inhibitor of ER stress) markedly reversed MBP-induced ER stress and apoptosis-related signals. Furthermore, exposure to MBP significantly induced the protein phosphorylation of JNK and AMP-activated protein kinase (AMPK)α. Pretreatment of β-cells with pharmacological inhibitors for JNK (SP600125) and AMPK (compound C), respectively, effectively abrogated the MBP-induced apoptosis-related signals. Both JNK and AMPK inhibitors also suppressed the MBP-induced activation of JNK and AMPKα and of each other. In conclusion, these findings suggest that MBP exposure exerts cytotoxicity on β-cells via the interdependent activation of JNK and AMPKα, which regulates the downstream apoptotic signaling pathway. 相似文献
35.
36.
37.
38.
Nitsa Buaron Antonella Mangraviti Francesco Volpin Ann Liu Mariangela Pedone Eric Sankey Dina Aranovich Itay Adar Fausto J. Rodriguez Abraham Nyska Riki Goldbart Tamar Traitel Henry Brem Betty Tyler Joseph Kost 《Advanced functional materials》2021,31(44):2100643
Treating neuroinflammation-related injuries and disorders through manipulation of neuroinflammation functions is being heralded as a new therapeutic strategy. In this study, a novel pectic galactan (PG) polysaccharide based gene therapy approach is developed for targeting reactive gliosis in neuroinflammation. Galectin-3 (Gal-3) is a cell protein with a high affinity to β-galactoside sugars and is highly expressed in reactive gliosis. Since PG carries galactans, it can target reactive gliosis via specific carbohydrate interaction between galactan and Gal-3 on the cell membrane, and therefore can be utilized as a carrier for delivering genes to these cells. The carrier is synthesized by modifying quaternary ammonium groups on the PG. The resulting quaternized PG (QPG) is found to form complexes with plasmid DNA with a mean diameter of 100 nm and have the characteristics required for targeted gene therapy. The complexes efficiently condense large amounts of plasmid per particle and successfully bind to Gal-3. The in vivo study shows that the complexes are biocompatible and safe for administration and can selectively transfect reactive glial cells of an induced cortical lesion. The results confirm that this PG-based delivery system is a promising platform for targeting Gal-3 overexpressing neuroinflammation cells for treating neuroinflammation-related injuries and neurodegenerative diseases. 相似文献
39.
40.