全文获取类型
收费全文 | 79839篇 |
免费 | 7135篇 |
国内免费 | 3923篇 |
专业分类
电工技术 | 4967篇 |
技术理论 | 4篇 |
综合类 | 5655篇 |
化学工业 | 13271篇 |
金属工艺 | 4741篇 |
机械仪表 | 5065篇 |
建筑科学 | 6039篇 |
矿业工程 | 2070篇 |
能源动力 | 2163篇 |
轻工业 | 5681篇 |
水利工程 | 1538篇 |
石油天然气 | 4113篇 |
武器工业 | 678篇 |
无线电 | 9724篇 |
一般工业技术 | 10394篇 |
冶金工业 | 3540篇 |
原子能技术 | 942篇 |
自动化技术 | 10312篇 |
出版年
2024年 | 343篇 |
2023年 | 1218篇 |
2022年 | 2295篇 |
2021年 | 3216篇 |
2020年 | 2387篇 |
2019年 | 2092篇 |
2018年 | 2203篇 |
2017年 | 2512篇 |
2016年 | 2416篇 |
2015年 | 3305篇 |
2014年 | 4011篇 |
2013年 | 4768篇 |
2012年 | 5125篇 |
2011年 | 5729篇 |
2010年 | 5092篇 |
2009年 | 4716篇 |
2008年 | 4616篇 |
2007年 | 4455篇 |
2006年 | 4388篇 |
2005年 | 3781篇 |
2004年 | 2688篇 |
2003年 | 2520篇 |
2002年 | 2797篇 |
2001年 | 2334篇 |
2000年 | 1975篇 |
1999年 | 1840篇 |
1998年 | 1455篇 |
1997年 | 1237篇 |
1996年 | 1109篇 |
1995年 | 983篇 |
1994年 | 833篇 |
1993年 | 615篇 |
1992年 | 458篇 |
1991年 | 341篇 |
1990年 | 250篇 |
1989年 | 198篇 |
1988年 | 183篇 |
1987年 | 105篇 |
1986年 | 79篇 |
1985年 | 52篇 |
1984年 | 40篇 |
1983年 | 27篇 |
1982年 | 32篇 |
1981年 | 26篇 |
1980年 | 17篇 |
1979年 | 8篇 |
1976年 | 8篇 |
1975年 | 7篇 |
1959年 | 6篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
Yuxi Guo Xuefeng Chen Pin Gong Fuxin Chen Dandan Cui Mengrao Wang 《International Journal of Food Science & Technology》2021,56(10):4970-4982
In vitro digestion models are widely used to study the structural changes, digestion and release of food components under simulated gastrointestinal conditions. As compared to the in vivo digestion tests, the in vitro digestion reflects the digestion and utilisation of food after ingestion and has the advantages of being time consuming, inexpensive, reproducible and free from moral and ethical restrictions. This study reviewed the current research studies on the in vitro simulated digestion of polysaccharides conducted in the last 5 years and focused on the oral, gastric and intestinal digestion models, with the aim of providing a basis for the further testing of changes in the content, structure and active ingredients of polysaccharides before and after digestion. 相似文献
32.
33.
Muhammad Sheeraz Mamoon Ur Rashid Asad Ali Fazli Akram Ho Jeong Lee Jin San Choi Jong-Seong Bae Yong Soo Kim Young-Han Shin Chang Won Ahn Tae Heon Kim 《Journal of the European Ceramic Society》2021,41(10):5155-5162
We demonstrate the structural evolution of polymorphic phases in Al2O3-inserted SrMnO3 ceramics synthesized by solid state reaction. While the 4H-hexagonal phase is predominant in pure SrMnO3 ceramics, a small amount of 6H-hexagonal polymorph is identified in addition to the primary 4H-hexagonal SrMnO3 and the secondary hexagonal SrAl2O4 phases in the as-sintered ceramics, evidenced by x-ray diffraction and subsequent Rietveld refinement analyses. The existence of the 6H-hexagonal SrMnO3 phase is corroborated using Raman spectroscopy. The chemical compositions and electronic structures of the Al2O3-inserted SrMnO3 compounds are also examined using energy dispersive spectroscopy and x-ray photoelectron spectroscopy, respectively. The first-principles calculations reveal that there is no clear difference between the total energies of 4H- and 6H-hexagonal polymorphs regardless of the presence/absence of Sr and oxygen vacancies. Possible origins are discussed with the estimation of actual strain based on the refined lattice parameter of 6H SrMnO3. 相似文献
34.
Journal of Computer Science and Technology - DOACROSS loops are significant parts in many important scientific and engineering applications, which are generally exploited pipeline/wave-front... 相似文献
35.
目前瞬变电磁法勘探广泛运用在煤矿系统,主要解决地下水的问题.随着科技的发展和进步,瞬变电磁法勘探仪器大致分2类,国外仪器一般采用大功率、大线框的大定源框内回装置;国内仪器一般采用小功率小线圈、低电压、高电流的重叠回线装置.在作业过程中,瞬变电磁法发射线框与接收设备受电磁干扰较为严重,不同的工作装置优势不同,抗干扰能力不同.通过对山西潞安集团李村矿的工作研究,证明了采用不同工作装置在高压线附近进行勘探,可起到互补的作用,达到勘探的目的 . 相似文献
36.
Dr. Yahu A. Liu Dr. Qihui Jin Qiang Ding Dr. Xueshi Hao Tingting Mo Shanshan Yan Dr. Yefen Zou Dr. Zhihong Huang Xiaoyue Zhang Wenqi Gao Dr. Tom Y.-H. Wu Chun Li Dr. Badry Bursalaya Dr. Michael Di Donato Dr. You-Qing Zhang Lisa Deaton Dr. Weijun Shen Dr. Brandon Taylor Anwesh Kamireddy Dr. George Harb Dr. Jing Li Dr. Yong Jia Dr. Andrew M. Schumacher Dr. Bryan Laffitte Dr. Richard Glynne Dr. Shifeng Pan Dr. Peter McNamara Dr. Valentina Molteni Dr. Jon Loren 《ChemMedChem》2020,15(16):1562-1570
Loss of β-cell mass and function can lead to insufficient insulin levels and ultimately to hyperglycemia and diabetes mellitus. The mainstream treatment approach involves regulation of insulin levels; however, approaches intended to increase β-cell mass are less developed. Promoting β-cell proliferation with low-molecular-weight inhibitors of dual-specificity tyrosine-regulated kinase 1A (DYRK1A) offers the potential to treat diabetes with oral therapies by restoring β-cell mass, insulin content and glycemic control. GNF4877, a potent dual inhibitor of DYRK1A and glycogen synthase kinase 3β (GSK3β) was previously reported to induce primary human β-cell proliferation in vitro and in vivo. Herein, we describe the lead optimization that lead to the identification of GNF4877 from an aminopyrazine hit identified in a phenotypic high-throughput screening campaign measuring β-cell proliferation. 相似文献
37.
目的: 建立快速灵敏的LC-MS/MS法测定人血浆中阿莫西林浓度,并用于两种阿莫西林胶囊的一致性评价。方法: 采用岛津公司LCMS-8060型LC-MS/MS仪,以MRM模式测定阿莫西林(m/z 366.00/114.00)的浓度,d4-阿莫西林作内标(m/z 370.10/114.05),离子源为ESI源。色谱柱选用Waters ACQUITY BEH C18(2.1×50 mm,1.7 μm),梯度洗脱。血浆样本加入内标,经甲醇沉淀蛋白后取上清液进样检测。结果: 所建方法经验证,其线性、准确度、精密度、最低定量限、提取回收率、特异性、基质效应、稳定性等各项指标均符合CFDA的指导原则及最新核查标准要求,并较文献报道中的方法有处理简单、灵敏度高、色谱峰形好的优点。结论: 所建方法快速、灵敏,适用于人血浆中阿莫西林浓度的检测。用于一致性评价的样本实测,两种制剂生物等效。 相似文献
38.
Baizhan Li Chenqiu Du Hong Liu Wei Yu Jie Zheng Meilan Tan Zhenxing Jin Wenjie Li Jing Wu Lu Chen Runming Yao 《Indoor air》2019,29(2):308-319
The extensive research interests in environmental temperature can be linked to human productivity / performance as well as comfort and health; while the mechanisms of physiological indices responding to temperature variations remain incompletely understood. This study adopted a physiological sensory nerve conduction velocity (SCV) as a temperature‐sensitive biomarker to explore the thermoregulatory mechanisms of human responding to annual temperatures. The measurements of subjects’ SCV (over 600 samples) were conducted in a naturally ventilated environment over all four seasons. The results showed a positive correlation between SCV and annual temperatures and a Boltzmann model was adopted to depict the S‐shaped trend of SCV with operative temperatures from 5°C to 40°C. The SCV increased linearly with operative temperatures from 14.28°C to 20.5°C and responded sensitively for 10.19°C‐24.59°C, while tended to be stable beyond that. The subjects’ thermal sensations were linearly related to SCV, elaborating the relation between human physiological regulations and subjective thermal perception variations. The findings reveal the body SCV regulatory characteristics in different operative temperature intervals, thereby giving a deeper insight into human autonomic thermoregulation and benefiting for built environment designs, meantime minimizing the temperature‐invoked risks to human health and well‐being. 相似文献
39.
40.
Hwang Seongil Park Sang Hyun Jin Maolin Kang Sang Hoon 《Intelligent Service Robotics》2021,14(3):471-484
Intelligent Service Robotics - A robust control designed for multiple degrees-of-freedom (DOF) robot manipulators performing complex tasks requiring frequent physical interaction with unknown... 相似文献