全文获取类型
收费全文 | 253605篇 |
免费 | 34542篇 |
国内免费 | 11591篇 |
专业分类
电工技术 | 16858篇 |
技术理论 | 16篇 |
综合类 | 16277篇 |
化学工业 | 48931篇 |
金属工艺 | 13774篇 |
机械仪表 | 15721篇 |
建筑科学 | 19962篇 |
矿业工程 | 7107篇 |
能源动力 | 7282篇 |
轻工业 | 21319篇 |
水利工程 | 4934篇 |
石油天然气 | 12883篇 |
武器工业 | 2254篇 |
无线电 | 31370篇 |
一般工业技术 | 34502篇 |
冶金工业 | 9837篇 |
原子能技术 | 2652篇 |
自动化技术 | 34059篇 |
出版年
2024年 | 828篇 |
2023年 | 3679篇 |
2022年 | 6994篇 |
2021年 | 10299篇 |
2020年 | 8943篇 |
2019年 | 8744篇 |
2018年 | 9324篇 |
2017年 | 10484篇 |
2016年 | 10344篇 |
2015年 | 13263篇 |
2014年 | 15265篇 |
2013年 | 18432篇 |
2012年 | 18256篇 |
2011年 | 18816篇 |
2010年 | 16945篇 |
2009年 | 16197篇 |
2008年 | 15553篇 |
2007年 | 14339篇 |
2006年 | 13988篇 |
2005年 | 11700篇 |
2004年 | 8242篇 |
2003年 | 7273篇 |
2002年 | 7189篇 |
2001年 | 6319篇 |
2000年 | 5695篇 |
1999年 | 4898篇 |
1998年 | 3366篇 |
1997年 | 2786篇 |
1996年 | 2662篇 |
1995年 | 2119篇 |
1994年 | 1738篇 |
1993年 | 1155篇 |
1992年 | 1005篇 |
1991年 | 678篇 |
1990年 | 534篇 |
1989年 | 451篇 |
1988年 | 343篇 |
1987年 | 227篇 |
1986年 | 168篇 |
1985年 | 117篇 |
1984年 | 72篇 |
1983年 | 60篇 |
1982年 | 69篇 |
1981年 | 47篇 |
1980年 | 48篇 |
1979年 | 29篇 |
1977年 | 4篇 |
1976年 | 10篇 |
1959年 | 15篇 |
1951年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
结合目前国外钻机现状以及国际石油钻井市场对钻机的配套要求,分析指出我国目前陆地钻机存在的不足与差距,对我国钻机及其配套技术的发展提出建议。 相似文献
92.
Fundamental Evaluation of Power Supply and Rectifiers for Wireless Power Transfer Using Magnetic Resonant Coupling 下载免费PDF全文
This paper provides a fundamental analysis of a power supply and rectifiers for wireless power transfer using magnetic resonant coupling (MRC). MRC enables efficient wireless power transfer over middle‐range transfer distances. MRC for wireless power transfer should operate at a high frequency in the industry science medical band, such as 13.56 MHz, because the size of the transfer device decreases at higher transfer frequencies. Therefore, the output frequency of the power supply on the transmitting side should be 13.56 MHz. In addition, the rectifier on the receiving side is operated at a high frequency. This paper focuses on the reflected power in the power supply and rectifiers. Thus, the parametric design method is clarified for the power supply, including a low‐pass filter to match the output, the impedance of the power supply with the characteristic impedance of the transmission line. In addition, the effects on the rectifiers of silicon carbide and gallium nitride diodes are confirmed by performing an experiment and a loss analysis. 相似文献
93.
Xuejing Lin Zhangxiao Peng Changqing Su 《International journal of molecular sciences》2015,16(5):10888-10906
Costunolide (CE) and dehydrocostuslactone (DE) are derived from many species of medicinal plants, such as Saussurea lappa Decne and Laurus nobilis L. They have been reported for their wide spectrum of biological effects, including anti-inflammatory, anticancer, antiviral, antimicrobial, antifungal, antioxidant, antidiabetic, antiulcer, and anthelmintic activities. In recent years, they have caused extensive interest in researchers due to their potential anti-cancer activities for various types of cancer, and their anti-cancer mechanisms, including causing cell cycle arrest, inducing apoptosis and differentiation, promoting the aggregation of microtubule protein, inhibiting the activity of telomerase, inhibiting metastasis and invasion, reversing multidrug resistance, restraining angiogenesis has been studied. This review will summarize anti-cancer activities and associated molecular mechanisms of these two compounds for the purpose of promoting their research and application. 相似文献
94.
95.
Lü Qing Xu Bin Yu Yang Zhan Wei Zhao Yu Zheng Jun Ji Jian 《Bulletin of Engineering Geology and the Environment》2021,80(8):6513-6525
Bulletin of Engineering Geology and the Environment - Many uncertainties exist in pile-stabilized slopes which make their design substantially complicated. In this paper, a first-order reliability... 相似文献
96.
Dr. Adarshi P. Welegedara Dr. Ansis Maleckis Ruchira Bandara Dr. Mithun C. Mahawaththa Iresha Dilhani Herath Yi Jiun Tan Dr. Angeliki Giannoulis Prof. Daniella Goldfarb Prof. Gottfried Otting Prof. Thomas Huber 《Chembiochem : a European journal of chemical biology》2021,22(8):1480-1486
The selenol group of selenocysteine is much more nucleophilic than the thiol group of cysteine. Selenocysteine residues in proteins thus offer reactive points for rapid post-translational modification. Herein, we show that selenoproteins can be expressed in high yield and purity by cell-free protein synthesis by global substitution of cysteine by selenocysteine. Complete alkylation of solvent-exposed selenocysteine residues was achieved in 10 minutes with 4-chloromethylene dipicolinic acid (4Cl-MDPA) under conditions that left cysteine residues unchanged even after overnight incubation. GdIII−GdIII distances measured by double electron–electron resonance (DEER) experiments of maltose binding protein (MBP) containing two selenocysteine residues tagged with 4Cl-MDPA-GdIII were indistinguishable from GdIII−GdIII distances measured of MBP containing cysteine reacted with 4Br-MDPA tags. 相似文献
97.
98.
99.
Nazir Kizzie‐Hayford Doris Jaros Yvonne Schneider Harald Rohm 《International Journal of Food Science & Technology》2015,50(2):381-388
A standard method for the extraction of tiger nut milk has been introduced. It has been shown that, although milling duration improves the yield of tiger nut milk solids and its nutrient composition, there is a quantifiable loss of nutrient in the pressing residue during milk extraction. Milling duration improved the colloidal stability of the milk against creaming during 16 h of storage. A higher milling intensity resulted in the aggregation of biological polymers which resulted in colloidal destabilisation. Milling improved the lightness and stability and reduced browning rate of the tiger nut milk during storage. This report is important for the production of tiger nut milk of consistent and comparable characteristics. Milling has been introduced as a processing method for the qualitative and quantitative modulation of the properties of tiger nut milk. It is recommended to develop further strategies to improve the colloidal stability of tiger nut milk as a beverage. 相似文献
100.