全文获取类型
收费全文 | 14110篇 |
免费 | 1095篇 |
国内免费 | 986篇 |
专业分类
电工技术 | 431篇 |
技术理论 | 1篇 |
综合类 | 986篇 |
化学工业 | 1743篇 |
金属工艺 | 291篇 |
机械仪表 | 534篇 |
建筑科学 | 653篇 |
矿业工程 | 210篇 |
能源动力 | 1284篇 |
轻工业 | 689篇 |
水利工程 | 107篇 |
石油天然气 | 187篇 |
武器工业 | 2067篇 |
无线电 | 2666篇 |
一般工业技术 | 1507篇 |
冶金工业 | 239篇 |
原子能技术 | 1786篇 |
自动化技术 | 810篇 |
出版年
2024年 | 44篇 |
2023年 | 143篇 |
2022年 | 337篇 |
2021年 | 442篇 |
2020年 | 359篇 |
2019年 | 336篇 |
2018年 | 264篇 |
2017年 | 426篇 |
2016年 | 486篇 |
2015年 | 429篇 |
2014年 | 660篇 |
2013年 | 1043篇 |
2012年 | 876篇 |
2011年 | 1072篇 |
2010年 | 823篇 |
2009年 | 899篇 |
2008年 | 703篇 |
2007年 | 964篇 |
2006年 | 877篇 |
2005年 | 721篇 |
2004年 | 610篇 |
2003年 | 601篇 |
2002年 | 538篇 |
2001年 | 430篇 |
2000年 | 346篇 |
1999年 | 291篇 |
1998年 | 220篇 |
1997年 | 167篇 |
1996年 | 176篇 |
1995年 | 148篇 |
1994年 | 130篇 |
1993年 | 108篇 |
1992年 | 100篇 |
1991年 | 82篇 |
1990年 | 66篇 |
1989年 | 36篇 |
1988年 | 49篇 |
1987年 | 40篇 |
1986年 | 27篇 |
1985年 | 32篇 |
1984年 | 24篇 |
1983年 | 14篇 |
1982年 | 18篇 |
1981年 | 10篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1964年 | 1篇 |
1962年 | 1篇 |
1959年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
张京萍 《特种铸造及有色合金》2002,(Z1)
分析了国际、国内镁业现状及国际市场对我国镁出口的反倾销的原因 ,提出了我国镁业应付反倾销的对策及发展方向 相似文献
102.
103.
Simonetta Pazzaglia Barbara Tanno Francesca Antonelli Paola Giardullo Gabriele Babini Prabal Subedi Omid Azimzadeh Zohaib N. Khan Kateryna Oleksenko Fabian Metzger Christine von Toerne Damien Traynor Dinesh Medipally Aidan D. Meade Munira Kadhim Fiona M. Lyng Soile Tapio Anna Saran Mariateresa Mancuso 《International journal of molecular sciences》2021,22(8)
The brain undergoes ionizing radiation exposure in many clinical situations, particularly during radiotherapy for brain tumors. The critical role of the hippocampus in the pathogenesis of radiation-induced neurocognitive dysfunction is well recognized. The goal of this study is to test the potential contribution of non-targeted effects in the detrimental response of the hippocampus to irradiation and to elucidate the mechanisms involved. C57Bl/6 mice were whole body (WBI) or partial body (PBI) irradiated with 0.1 or 2.0 Gy of X-rays or sham irradiated. PBI consisted of the exposure of the lower third of the mouse body, whilst the upper two thirds were shielded. Hippocampi were collected 15 days or 6 months post-irradiation and a multi-omics approach was adopted to assess the molecular changes in non-coding RNAs, proteins and metabolic levels, as well as histological changes in the rate of hippocampal neurogenesis. Notably, at 2.0 Gy the pattern of early molecular and histopathological changes induced in the hippocampus at 15 days following PBI were similar in quality and quantity to the effects induced by WBI, thus providing a proof of principle of the existence of out-of-target radiation response in the hippocampus of conventional mice. We detected major alterations in DAG/IP3 and TGF-β signaling pathways as well as in the expression of proteins involved in the regulation of long-term neuronal synaptic plasticity and synapse organization, coupled with defects in neural stem cells self-renewal in the hippocampal dentate gyrus. However, compared to the persistence of the WBI effects, most of the PBI effects were only transient and tended to decrease at 6 months post-irradiation, indicating important mechanistic difference. On the contrary, at low dose we identified a progressive accumulation of molecular defects that tended to manifest at later post-irradiation times. These data, indicating that both targeted and non-targeted radiation effects might contribute to the pathogenesis of hippocampal radiation-damage, have general implications for human health. 相似文献
104.
Chandrasekharam N. Nagineni Sarwat Naz Rajani Choudhuri Gadisetti V. R. Chandramouli Murali C. Krishna Jeffrey R. Brender John A. Cook James B. Mitchell 《International journal of molecular sciences》2021,22(9)
Understanding the global metabolic changes during the senescence of tumor cells can have implications for developing effective anti-cancer treatment strategies. Ionizing radiation (IR) was used to induce senescence in a human colon cancer cell line HCT-116 to examine secretome and metabolome profiles. Control proliferating and senescent cancer cells (SCC) exhibited distinct morphological differences and expression of senescent markers. Enhanced secretion of pro-inflammatory chemokines and IL-1, anti-inflammatory IL-27, and TGF-β1 was observed in SCC. Significantly reduced levels of VEGF-A indicated anti-angiogenic activities of SCC. Elevated levels of tissue inhibitors of matrix metalloproteinases from SCC support the maintenance of the extracellular matrix. Adenylate and guanylate energy charge levels and redox components NAD and NADP and glutathione were maintained at near optimal levels indicating the viability of SCC. Significant accumulation of pyruvate, lactate, and suppression of the TCA cycle in SCC indicated aerobic glycolysis as the predominant energy source for SCC. Levels of several key amino acids decreased significantly, suggesting augmented utilization for protein synthesis and for use as intermediates for energy metabolism in SCC. These observations may provide a better understanding of cellular senescence basic mechanisms in tumor tissues and provide opportunities to improve cancer treatment. 相似文献
105.
106.
107.
Ce^3+,Sb^3+共激活的亚超细磷光体的微波快速合成和发光特性 总被引:5,自引:0,他引:5
首次采用微波辐射法快速合成了亚超细CaS:C^3 ,Sb^3 高效绿光磷光体,发现Ce^3 与Sb^3 离子之间存在着能量传,租是属于多极子相互作用的共振传递,因而Ce^3 对CaS:Sb^3 的发光有明显的敏化和增强。微波场作用下合成的双掺磷光体的激发峰与发射峰值分别恒定在259nm 和523nm处,并没有像传统高温固相合成法那样,随掺杂离子浓度的增大而发生红移现象。SEM照片显示,采用含不同一价阳离子(Na^ ,K^ ,NH4^ )无机盐作助熔剂制得的亚超细CaS:Ce^3 ,Sb^3 磷光体平均粒径为300nm-500nm,但其晶体形貌分别为立方形、球形和团聚状的雪花形,其中球形磷光体荧光最强。 相似文献
108.
109.
夜面涂装加热与干燥设备是近年来开发的节电新技术,可较传统热风炉或一般远红外炉节电15~40%,炉内上下温差3~8℃。文章提出用系统优化的原理和方法对乳白石英管低温辐射加热进行研究,设计中采用辐射密度分布法和部份功率控制法。 相似文献
110.