全文获取类型
收费全文 | 20420篇 |
免费 | 2086篇 |
国内免费 | 1302篇 |
专业分类
电工技术 | 1540篇 |
综合类 | 1873篇 |
化学工业 | 3277篇 |
金属工艺 | 1019篇 |
机械仪表 | 1207篇 |
建筑科学 | 1602篇 |
矿业工程 | 634篇 |
能源动力 | 478篇 |
轻工业 | 2546篇 |
水利工程 | 493篇 |
石油天然气 | 906篇 |
武器工业 | 199篇 |
无线电 | 2059篇 |
一般工业技术 | 1954篇 |
冶金工业 | 901篇 |
原子能技术 | 382篇 |
自动化技术 | 2738篇 |
出版年
2024年 | 113篇 |
2023年 | 401篇 |
2022年 | 771篇 |
2021年 | 956篇 |
2020年 | 741篇 |
2019年 | 531篇 |
2018年 | 576篇 |
2017年 | 640篇 |
2016年 | 537篇 |
2015年 | 878篇 |
2014年 | 1145篇 |
2013年 | 1316篇 |
2012年 | 1484篇 |
2011年 | 1638篇 |
2010年 | 1478篇 |
2009年 | 1403篇 |
2008年 | 1422篇 |
2007年 | 1367篇 |
2006年 | 1255篇 |
2005年 | 1121篇 |
2004年 | 768篇 |
2003年 | 522篇 |
2002年 | 572篇 |
2001年 | 466篇 |
2000年 | 406篇 |
1999年 | 268篇 |
1998年 | 179篇 |
1997年 | 151篇 |
1996年 | 134篇 |
1995年 | 112篇 |
1994年 | 95篇 |
1993年 | 65篇 |
1992年 | 52篇 |
1991年 | 53篇 |
1990年 | 33篇 |
1989年 | 28篇 |
1988年 | 26篇 |
1987年 | 14篇 |
1986年 | 19篇 |
1985年 | 9篇 |
1984年 | 12篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 10篇 |
1980年 | 11篇 |
1979年 | 5篇 |
1977年 | 2篇 |
1974年 | 4篇 |
1959年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
41.
Sung-Chou Li Kuo-Chung Lan Hsuan-Ning Hung Wan-Ting Huang Yun-Ju Lai Hsin-Hsin Cheng Chih-Chang Tsai Kun-Long Huang Huey-Ling You Te-Yao Hsu 《International journal of molecular sciences》2022,23(10)
Placenta accreta spectrum (PAS) accounts for 7% of maternal mortality and is associated with intraoperative and postoperative morbidity caused by massive blood loss, infection, and adjacent organ damage. The aims of this study were to identify the protein biomarkers of PAS and to further explore their pathogenetic roles in PAS. For this purpose, we collected five placentas from pregnant subjects with PAS complications and another five placentas from normal pregnancy (NP) cases. Then, we enriched protein samples by specifically isolating the trophoblast villous, deeply invading into the uterine muscle layer in the PAS patients. Next, fluorescence-based two-dimensional difference gel electrophoresis (2D-DIGE) and MALDI-TOF/MS were used to identify the proteins differentially abundant between PAS and NP placenta tissues. As a result, nineteen spots were determined as differentially abundant proteins, ten and nine of which were more abundant in PAS and NP placenta tissues, respectively. Then, specific validation with western blot assay and immunohisto/cytochemistry (IHC) assay confirmed that heat shock 70 kDa protein 4 (HSPA4) and chorionic somatomammotropin hormone (CSH) were PAS protein biomarkers. Further tube formation assays demonstrated that HSPA4 promoted the in vitro angiogenesis ability of vessel endothelial cells, which is consistent with the in vivo scenario of PAS complications. In this study, we not only identified PAS protein biomarkers but also connected the promoted angiogenesis with placenta invasion, investigating the pathogenetic mechanism of PAS. 相似文献
42.
43.
44.
现有的服务组合描述途径不能有效地验证和测试组合正确性,针对这一问题,提出了一个代数规约方法,引入规约包机制扩展面向服务代数规约语言SOFIA以支持该方法。用代数规约单元描述服务系统中的各种实体,其中基调部分定义实体的语法和结构,公理部分定义其功能和行为特性。与一个服务相关的规约单元封装在一个包中或拆分在几个相互引用的包中,每个包形成一个命名空间。当多个服务组合在一起时,以这些服务的代数规约包为基础,一方面抽象地定义组合服务的交互过程和语义,形成描述服务组合实现方式的实现规约包;另一方面抽象地定义组合服务对外接口及其功能语义,形成描述组合服务需求的抽象规约包。在实现规约和抽象规约的双元结构基础上,进一步定义了实现规约和抽象规约之间必须满足的“实现”关系,证明了满足实现关系可以保证实现的正确性,从而为服务组合的可验证性和可测试性奠定了理论基础。最后结合实例分析阐述了用代数规约描述服务组合的抽象性、可表达性和可验证性。 相似文献
45.
46.
Bai Yun Gu Yuanqi Lan Qi Fan Liyun Ma Xiuzhen 《Journal of Mechanical Science and Technology》2020,34(6):2647-2656
Journal of Mechanical Science and Technology - Common rail system is a key technology of energy saving and emission reduction for modern diesel engines. Multiple injection, as one of the most... 相似文献
47.
介绍了实现标准广播电视制式的768×576 256 bit隔行扫描全屏显示的维吾尔和哈萨克文电视图文演播软件的研制方法,针对维吾尔和哈萨克文字的书写特点研究了自动选形和连写处理等几个关键编程技术。 相似文献
48.
49.
Lan Yang Shiqi Huang Zhirong Zhang Zhenmi Liu Ling Zhang 《International journal of molecular sciences》2022,23(11)
Red blood cell-derived extracellular vesicles (RBCEVs) are vesicles naturally produced by red blood cells and play multiple roles such as acting as cell-to-cell communication messengers in both normal physiological and diseased states. RBCEVs are highly promising delivery vehicles for therapeutic agents such as biomolecules and nucleic acids as they are easy to source, safe, and versatile. RBCEVs autonomously target the liver and pass the blood–brain barrier into the brain, which is highly valuable for the treatment of liver and brain diseases. RBCEVs can be modified by various functional units, including various functional molecules and nanoparticles, to improve their active targeting capabilities for tumors or other sites. Moreover, the RBCEV level is significantly shifted in many diseased states; hence, they can also serve as important biomarkers for disease diagnoses. It is clear that RBCEVs have considerable potential in multiple medical applications. In this review, we briefly introduce the biological roles of RBCEVs, presented interesting advances in RBCEV applications, and discuss several challenges that need to be addressed for their clinical translation. 相似文献
50.
Tianchi Zhou Yaxin Zhang Bo Zhang Hongxin Zeng Zhiyong Tan Xilin Zhang Lan Wang Zhi Chen Juncheng Cao Kaijun Song Ziqiang Yang 《中国通信》2021,(5):221-244
Terahertz communication technology can provide abundant frequency resources,strong confidentiality,antijamming capability,communication tracking capability and ... 相似文献