全文获取类型
收费全文 | 252190篇 |
免费 | 33288篇 |
国内免费 | 12498篇 |
专业分类
电工技术 | 15181篇 |
技术理论 | 8篇 |
综合类 | 17878篇 |
化学工业 | 48695篇 |
金属工艺 | 13595篇 |
机械仪表 | 15071篇 |
建筑科学 | 18218篇 |
矿业工程 | 6571篇 |
能源动力 | 7275篇 |
轻工业 | 23388篇 |
水利工程 | 5072篇 |
石油天然气 | 11016篇 |
武器工业 | 2182篇 |
无线电 | 31543篇 |
一般工业技术 | 33474篇 |
冶金工业 | 10192篇 |
原子能技术 | 3108篇 |
自动化技术 | 35509篇 |
出版年
2024年 | 877篇 |
2023年 | 2856篇 |
2022年 | 5622篇 |
2021年 | 8220篇 |
2020年 | 7293篇 |
2019年 | 7877篇 |
2018年 | 8324篇 |
2017年 | 9495篇 |
2016年 | 9495篇 |
2015年 | 12112篇 |
2014年 | 14644篇 |
2013年 | 17625篇 |
2012年 | 17602篇 |
2011年 | 18692篇 |
2010年 | 17830篇 |
2009年 | 17039篇 |
2008年 | 16638篇 |
2007年 | 16043篇 |
2006年 | 15375篇 |
2005年 | 12679篇 |
2004年 | 9686篇 |
2003年 | 8447篇 |
2002年 | 8776篇 |
2001年 | 7460篇 |
2000年 | 6206篇 |
1999年 | 4747篇 |
1998年 | 2961篇 |
1997年 | 2513篇 |
1996年 | 2299篇 |
1995年 | 1968篇 |
1994年 | 1525篇 |
1993年 | 1087篇 |
1992年 | 838篇 |
1991年 | 663篇 |
1990年 | 531篇 |
1989年 | 417篇 |
1988年 | 343篇 |
1987年 | 247篇 |
1986年 | 186篇 |
1985年 | 136篇 |
1984年 | 118篇 |
1983年 | 98篇 |
1982年 | 68篇 |
1981年 | 69篇 |
1980年 | 49篇 |
1979年 | 29篇 |
1978年 | 19篇 |
1977年 | 31篇 |
1976年 | 32篇 |
1959年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
2.
Shanshan Zhuang Wenxiong Zheng Yunong Na Naiyi Chen Fan Gong Bingxuan Huang Stephen Brennan Charles Congyi Liu Jian Cheng Lukai Ma Huifan Liu 《International Journal of Food Science & Technology》2022,57(2):1093-1103
The β-Carotene (BC), an important precursor of vitamin A (VA), possesses antioxidant activity but is fat-soluble and has low bioavailability. In previous in-vitro assays evaluating antioxidant and 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) free radical scavenging, both BC and VA showed a strong ability to scavenge radicals and protected cells from oxidative stress. Here, we used artificially simulated gastrointestinal digestion and Caco-2 cell absorption models to evaluate the bioavailability of the BC during gastrointestinal digestion and absorption using high-performance liquid chromatography (HPLC) analysis. We observed high absorptive and transfer rates of BC and detected retinol metabolites (Vitamin A). Therefore, BC can be detected in the acidic gastrointestinal environment using HPLC. Optimised method provided better separation of BC and VA in the column, improving the accuracy of the test results. 相似文献
3.
Mengru Liu Weihai Zhang Limin Ma 《International Journal of Adaptive Control and Signal Processing》2022,36(1):69-87
The article investigates the finite-time adaptive fuzzy control for a class of nonlinear systems with output constraint and input dead-zone. First, by skillfully combining the barrier Lyapunov function, backstepping design method, and finite-time control theory, a novel adaptive state-feedback tracking controller is constructed, and the output constraint of the nonlinear system is not violated. Second, the fuzzy logic system is used to approximate unknown function in the nonlinear system. Third, the finite-time command filter is introduced to avoid the problem of “complexity explosion” caused by repeated differentiations of the virtual control signal in conventional backstepping control schemes. Meanwhile, a new saturation function is added in the compensating signal for filter error to improve control accuracy. Finally, based on Lyapunov stability analysis, all the signals of the closed-loop are proved to be semi-globally uniformly ultimately bounded, and the tracking error converges to a small neighborhood region of the origin in a finite time. A simulation example is presented to demonstrate the effectiveness for the proposed control scheme. 相似文献
4.
Fan Deng-Ping Huang Ziling Zheng Peng Liu Hong Qin Xuebin Van Gool Luc 《国际自动化与计算杂志》2022,19(4):257-287
Machine Intelligence Research - This paper aims to conduct a comprehensive study on facial-sketch synthesis (FSS). However, due to the high cost of obtaining hand-drawn sketch datasets, there is a... 相似文献
5.
Applied Composite Materials - In this paper, the low-velocity impact deformation behavior of biaxial warp-knitted flexible composite was investigated. A simplified finite element model (FEM) of the... 相似文献
6.
Jing-jie Xie Xiao-Li Zou Yan-ping Li Zhuang-Li Kang Han-jun Ma 《International Journal of Food Science & Technology》2022,57(4):2459-2466
The effects of high-pressure-modified soy 11S globulin (0.1, 200, and 400 MPa) on the gel properties, water-holding capacity, and water mobility of pork batter were investigated. The high-pressure-modified soy 11S globulin significantly increased (P < 0.05) the emulsion stability, cooking yield, hardness, springiness, chewiness, resilience, cohesiveness, the a* and b* values, and the G′ and G′′ values of pork batter at 80 °C, compared with those of 0.1 MPa-modified globulin. In contrast, the centrifugal loss and initial relaxation time of T2b, T21, and T22 significantly decreased (P < 0.05). Meanwhile, the microstructure was denser, and the voids were smaller and more uniform compared with those of 0.1 MPa-modified globulin. In addition, the sample with 11S globulin modified at 400 MPa had the best water-holding capacity, gel structure, and gel properties among the samples. Overall, the use of high-pressure-modified soy 11S globulin improved the gel properties and water-holding capacity of pork batter, especially under 400 MPa. 相似文献
7.
Hong Sae Jin Park Nam Il Hwang Dae Keun Yi Tae Gyu Eum Hyang Lan 《Food science and biotechnology》2022,31(6):669-679
Food Science and Biotechnology - Various hilling materials (rice hulls, pine sawdust, and perlite) were compared to produce sprout vegetables using beach silvertop (Glehnia littoralis Fr. Schm. ex... 相似文献
8.
International Journal of Information Security - Machine learning techniques have been widely used and shown remarkable performance in various fields. Along with the widespread utilization of... 相似文献
10.
Photoresponsive biomaterials are experiencing a transition from in vitro models to in vivo demonstrations that point toward clinical translation. Dynamic hydrogels for cell encapsulation, light-responsive carriers for controlled drug delivery, and nanomaterials containing photosensitizers for photodynamic therapy are relevant examples. Nonetheless, the step to the clinic largely depends on their combination with technologies to bring light into the body. This review highlights the challenge of photoactivation in vivo, and presents strategies for light management that can be adopted for this purpose. The authors’ focus is on technologies that are materials-driven, particularly upconversion nanoparticles that assist in “direct path” light delivery through tissue, and optical waveguides that “clear the path” between external light source and in vivo target. The authors’ intention is to assist the photoresponsive biomaterials community transition toward medical technologies by presenting light delivery concepts that can be integrated with the photoresponsive targets. The authors also aim to stimulate further innovation in materials-based light delivery platforms by highlighting needs and opportunities for in vivo photoactivation of biomaterials. 相似文献