全文获取类型
收费全文 | 3194篇 |
免费 | 142篇 |
国内免费 | 15篇 |
专业分类
电工技术 | 41篇 |
综合类 | 13篇 |
化学工业 | 527篇 |
金属工艺 | 59篇 |
机械仪表 | 105篇 |
建筑科学 | 141篇 |
矿业工程 | 7篇 |
能源动力 | 102篇 |
轻工业 | 194篇 |
水利工程 | 26篇 |
石油天然气 | 7篇 |
无线电 | 561篇 |
一般工业技术 | 531篇 |
冶金工业 | 502篇 |
原子能技术 | 15篇 |
自动化技术 | 520篇 |
出版年
2023年 | 21篇 |
2022年 | 18篇 |
2021年 | 58篇 |
2020年 | 44篇 |
2019年 | 52篇 |
2018年 | 72篇 |
2017年 | 67篇 |
2016年 | 64篇 |
2015年 | 63篇 |
2014年 | 94篇 |
2013年 | 209篇 |
2012年 | 138篇 |
2011年 | 162篇 |
2010年 | 132篇 |
2009年 | 152篇 |
2008年 | 175篇 |
2007年 | 177篇 |
2006年 | 151篇 |
2005年 | 123篇 |
2004年 | 118篇 |
2003年 | 102篇 |
2002年 | 100篇 |
2001年 | 71篇 |
2000年 | 64篇 |
1999年 | 68篇 |
1998年 | 156篇 |
1997年 | 117篇 |
1996年 | 79篇 |
1995年 | 54篇 |
1994年 | 61篇 |
1993年 | 52篇 |
1992年 | 23篇 |
1991年 | 19篇 |
1990年 | 23篇 |
1989年 | 38篇 |
1988年 | 26篇 |
1987年 | 23篇 |
1986年 | 33篇 |
1985年 | 25篇 |
1984年 | 19篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 12篇 |
1980年 | 9篇 |
1979年 | 4篇 |
1978年 | 9篇 |
1977年 | 13篇 |
1976年 | 12篇 |
1973年 | 6篇 |
1966年 | 3篇 |
排序方式: 共有3351条查询结果,搜索用时 109 毫秒
1.
2.
Hou Kaiming Bavisotto Robert Manzi Sergio Javier Perez Eliseo Joaquín Furlong Octavio Javier Kotvis Peter Kenmoe Germaine Djuidje Tysoe Wilfred T. 《Tribology Letters》2022,70(2):1-19
Tribology Letters - Most asteroids with a diameter larger than $$\sim 300 \ {\mathrm{m}}$$ are rubble piles, i.e., consisting of more than one solid object. All asteroids are rotating but almost... 相似文献
3.
Laser aided additive manufacturing(LAAM)was used to fabricate bulk Fe49.5Mn30Co10Cr10C0.5 interstitial multicomponent alloy using pre-alloyed powder.The room temperature yield strength(σy),ultimate tensile strength(σUTS)and elongation(εUST)were 645 MPa,917 MPa and 27.0%respectively.The as-built sample consisted of equiaxed and dendritic cellular structures formed by elemental segregation.These cellular structures together with oxide particle inclusions were deemed to strengthen the material.The other contributing components include dislocation strengthening,friction stress and grain bound-ary strengthening.The high εUTS was attributed to dislocation motion and activation of both twinning and transformation-induced plasticity(TWIP and TRIP).Tensile tests performed at-40℃and-130℃demonstrated superior tensile strength of 1041 MPa and 1267 MPa respectively.However,almost no twinning was observed in the fractured sample tested at-40℃and-130℃.Instead,higher fraction of strain-induced hexagonal close-packed(HCP)ε phase transformation of 21.2%were observed for fractured sample tested at-40℃,compared with 6.3%in fractured room temperature sample. 相似文献
4.
Wan Huan Wang Hui Scotney Bryan Liu Jun Ng Wing W. Y. 《Multimedia Tools and Applications》2020,79(39-40):29327-29352
Multimedia Tools and Applications - In many real-world classification problems there exist multiple subclasses (or clusters) within a class; in other words, the underlying data distribution is... 相似文献
5.
Lean practices are known to increase operational performance. Previous research has identified critical success factors for implementing lean practices. This research aims to examine the extent to which success factors are critical for various degrees of lean practice implementation. Using multiple-respondent self-assessments from 33 Dutch manufacturing small and medium-sized enterprises (SMEs), we conducted a Necessary Condition Analysis. Our findings indicated that the criticality of success factors is progression dependent. In the initial stages of the lean journey, SMEs could improve their lean practices in a bottom-up manner through local factors such as a learning focus, improvement training and support congruence. When lean practices are more advanced, some company-wide factors must be present: top management support, a shared improvement vision and a supplier link. Our findings question the universality of success factors such as strategic involvement and indicate the need for a more dynamic model of lean implementation. 相似文献
6.
Ng Mun-Kit Chong Yung-Wey Ko Kwang-man Park Young-Hoon Leau Yu-Beng 《Neural computing & applications》2020,32(17):13155-13171
Neural Computing and Applications - Warehouse robots have been widely used by manufacturers and online retailer to automate good delivery process. One of the fundamental components when designing a... 相似文献
7.
Qiang Peng Christine Yim-Ping Wong Isabella Wai-yin Cheuk Jeremy Yuen-Chun Teoh Peter Ka-Fung Chiu Chi-Fai Ng 《International journal of molecular sciences》2021,22(9)
Spermine, a member of polyamines, exists in all organisms and is essential for normal cell growth and function. It is highly expressed in the prostate compared with other organs and is detectable in urine, tissue, expressed prostatic secretions, and erythrocyte. A significant reduction of spermine level was observed in prostate cancer (PCa) tissue compared with benign prostate tissue, and the level of urinary spermine was also significantly lower in men with PCa. Decreased spermine level may be used as an indicator of malignant phenotype transformation from normal to malignant tissue in prostate. Studies targeting polyamines and key rate-limiting enzymes associated with spermine metabolism as a tool for PCa therapy and chemoprevention have been conducted with various polyamine biosynthesis inhibitors and polyamine analogues. The mechanism between spermine and PCa development are possibly related to the regulation of polyamine metabolism, cancer-driving pathways, oxidative stress, anticancer immunosurveillance, and apoptosis regulation. Although the specific mechanism of spermine in PCa development is still unclear, ongoing research in spermine metabolism and its association with PCa pathophysiology opens up new opportunities in the diagnostic and therapeutic roles of spermine in PCa management. 相似文献
8.
9.
Pattern Analysis and Applications - The identification of a person’s gender plays an important role in various visual surveillance and monitoring applications which are growing more... 相似文献
10.
Elias Martinez Hernandez Kok Siew Ng 《Clean Technologies and Environmental Policy》2018,20(7):1501-1514
Unlocking the potential and value of lignocellulosic residues is an important step in making biorefineries economically and environmentally promising. This calls for a holistic and systematic approach in designing sustainable industrial systems. In this work, biorefinery systems via biochemical route (acetone–butanol–ethanol or ABE system) and thermochemical route (gasification and mixed alcohols or GMA system) for converting corn stover into biofuels have been designed using a Sustainable Engineering Framework. The framework involves eight main steps: (1) design problem definition, (2) data collection, (3) process synthesis and simulation, (4) process integration, (5) resource recovery from residues, (6) utility system design, (7) economic and environmental modelling and (8) economic value and environmental impact margin analysis for decision making. Consideration of resource recovery from biorefinery waste streams has proven to be the key in making biorefineries self-sustaining and with low environmental impacts. Simultaneous economic and environmental feasibility assessment at the early stage of process design is highly envisaged. The cost of biofuel production in the ABE system has been found to be 49.2 US$/GJ and 69.9 US$/GJ in the GMA system. The greenhouse gas emissions are 46.2 g CO2-eq/GJ for ABE and 19.0 g CO2-eq/GJ for GMA, lower than gasoline (85 g CO2-eq/GJ). The GMA system is not economically compelling though with high environmental benefit, while the ABE system has shown to be both economically and environmentally feasible. 相似文献