全文获取类型
收费全文 | 3704篇 |
免费 | 255篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 64篇 |
综合类 | 2篇 |
化学工业 | 1098篇 |
金属工艺 | 86篇 |
机械仪表 | 104篇 |
建筑科学 | 95篇 |
矿业工程 | 4篇 |
能源动力 | 150篇 |
轻工业 | 649篇 |
水利工程 | 28篇 |
石油天然气 | 22篇 |
无线电 | 248篇 |
一般工业技术 | 660篇 |
冶金工业 | 328篇 |
原子能技术 | 21篇 |
自动化技术 | 406篇 |
出版年
2024年 | 10篇 |
2023年 | 37篇 |
2022年 | 124篇 |
2021年 | 180篇 |
2020年 | 118篇 |
2019年 | 137篇 |
2018年 | 140篇 |
2017年 | 145篇 |
2016年 | 156篇 |
2015年 | 107篇 |
2014年 | 187篇 |
2013年 | 255篇 |
2012年 | 246篇 |
2011年 | 246篇 |
2010年 | 200篇 |
2009年 | 221篇 |
2008年 | 176篇 |
2007年 | 178篇 |
2006年 | 132篇 |
2005年 | 99篇 |
2004年 | 75篇 |
2003年 | 80篇 |
2002年 | 60篇 |
2001年 | 53篇 |
2000年 | 35篇 |
1999年 | 45篇 |
1998年 | 99篇 |
1997年 | 72篇 |
1996年 | 47篇 |
1995年 | 35篇 |
1994年 | 31篇 |
1993年 | 32篇 |
1992年 | 17篇 |
1991年 | 22篇 |
1990年 | 21篇 |
1989年 | 15篇 |
1988年 | 27篇 |
1987年 | 13篇 |
1986年 | 12篇 |
1985年 | 14篇 |
1984年 | 7篇 |
1983年 | 6篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1977年 | 5篇 |
1976年 | 7篇 |
1974年 | 4篇 |
1972年 | 3篇 |
1971年 | 3篇 |
排序方式: 共有3965条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Photonic Network Communications - Optical packet switching is a prominent technology proposing not only a reduction in the energy consumption by the elimination of numerous... 相似文献
5.
6.
7.
8.
9.
P. Carrasqueira H. Rocha J. M. Dias T. Ventura B. C. Ferreira M. C. Lopes 《International Transactions in Operational Research》2023,30(1):206-223
Radiation therapy is a technology-driven cancer treatment modality that has experienced significant advances over the last decades, due to multidisciplinary contributions that include engineering and computing. Recent technological developments allow the use of noncoplanar volumetric modulated arc therapy (VMAT), one of the most recent photon treatment techniques, in clinical practice. In this work, an automated noncoplanar arc trajectory optimization framework designed in two modular phases is presented. First, a noncoplanar beam angle optimization algorithm is used to obtain a set of noncoplanar irradiation directions. Then, anchored in these directions, an optimization strategy is proposed to compute an optimal arc trajectory. The computational experiments considered a pool of twelve difficult head-and-neck tumor cases. It was possible to observe that, for some of these cases, the optimized noncoplanar arc trajectories led to significant treatment planning quality improvements, when compared with coplanar VMAT treatment plans. Although these experiments were done in a research environment treatment planning software (matRad), the conclusions can be of interest for a clinical setting: automated procedures can simplify the current treatment workflow, produce high-quality treatment plans, making better use of human resources and allowing for unbiased comparisons between different treatment techniques. 相似文献
10.
Vitamin D Compounds PRI-2191 and PRI-2205 Enhance Anastrozole Activity in Human Breast Cancer Models
Beata Filip-Psurska Mateusz Psurski Artur Anisiewicz Patrycja Libako Ewa Zbrojewicz Magdalena Maciejewska Micha Chodyski Andrzej Kutner Joanna Wietrzyk 《International journal of molecular sciences》2021,22(5)
1,25-Dihydroxycholecalciferol, the hormonally active vitamin D3 metabolite, is known to exhibit therapeutic effects against breast cancer, mainly by lowering the expression of estrogen receptors and aromatase activity. Previously, the safety of the vitamin D active metabolite (24R)-1,24-dihydroxycholecalciferol (PRI-2191) and 1,25(OH)2D3 analog PRI-2205 was tested, and the in vitro activity of these analogs against different cancer cell lines was studied. We determined the effect of the two vitamin D compounds on anastrozole (An) activity against breast cancer based on antiproliferative activity, ELISA, flow cytometry, enzyme inhibition potency, PCR, and xenograft study. Both the vitamin D active metabolite and synthetic analog regulated the growth of not only estrogen receptor-positive cells (T47D and MCF-7, in vitro and in vivo), but also hormone-independent cancer cells such as SKBR-3 (HER-2-positive) and MDA-MB-231 (triple-negative), despite their relatively low VDR expression. Combined with An, PRI-2191 and PRI-2205 significantly inhibited the tumor growth of MCF-7 cells. Potentiation of the antitumor activity in combined treatment of MCF-7 tumor-bearing mice is related to the reduced activity of aromatase by both An (enzyme inhibition) and vitamin D compounds (switched off/decreased aromatase gene expression, decreased expression of other genes related to estrogen signaling) and by regulation of the expression of the estrogen receptor ERα and VDR. 相似文献