全文获取类型
收费全文 | 88672篇 |
免费 | 8910篇 |
国内免费 | 5276篇 |
专业分类
电工技术 | 6676篇 |
技术理论 | 10篇 |
综合类 | 6825篇 |
化学工业 | 12798篇 |
金属工艺 | 5524篇 |
机械仪表 | 6290篇 |
建筑科学 | 7001篇 |
矿业工程 | 2731篇 |
能源动力 | 2618篇 |
轻工业 | 6309篇 |
水利工程 | 2291篇 |
石油天然气 | 4901篇 |
武器工业 | 982篇 |
无线电 | 10522篇 |
一般工业技术 | 9259篇 |
冶金工业 | 3848篇 |
原子能技术 | 1248篇 |
自动化技术 | 13025篇 |
出版年
2024年 | 422篇 |
2023年 | 1421篇 |
2022年 | 2716篇 |
2021年 | 3768篇 |
2020年 | 2857篇 |
2019年 | 2235篇 |
2018年 | 2625篇 |
2017年 | 2944篇 |
2016年 | 2742篇 |
2015年 | 3885篇 |
2014年 | 4876篇 |
2013年 | 5744篇 |
2012年 | 6508篇 |
2011年 | 7188篇 |
2010年 | 6441篇 |
2009年 | 6036篇 |
2008年 | 6139篇 |
2007年 | 5788篇 |
2006年 | 5174篇 |
2005年 | 4274篇 |
2004年 | 3047篇 |
2003年 | 2454篇 |
2002年 | 2397篇 |
2001年 | 2173篇 |
2000年 | 1743篇 |
1999年 | 1553篇 |
1998年 | 1123篇 |
1997年 | 880篇 |
1996年 | 785篇 |
1995年 | 669篇 |
1994年 | 552篇 |
1993年 | 383篇 |
1992年 | 300篇 |
1991年 | 211篇 |
1990年 | 164篇 |
1989年 | 137篇 |
1988年 | 102篇 |
1987年 | 71篇 |
1986年 | 66篇 |
1985年 | 31篇 |
1984年 | 32篇 |
1983年 | 30篇 |
1982年 | 24篇 |
1981年 | 26篇 |
1980年 | 25篇 |
1979年 | 22篇 |
1976年 | 13篇 |
1970年 | 6篇 |
1959年 | 8篇 |
1951年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Magnetic Resonance Materials in Physics, Biology and Medicine - To investigate the value of using diffusion-weighted imaging (DWI) and intravoxel incoherent motion DWI (IVIM-DWI) to assess the... 相似文献
22.
A first‐principles‐based effective Hamiltonian is developed and employed to investigate finite‐temperature structural properties of a prototype of perovskite halides, that is CsPbI3. Such simulations, when using first‐principles‐extracted coefficients, successfully reproduce the existence of an orthorhombic Pnma state and its iodine octahedral tilting angles around room temperature. However, they also yield a direct transformation from Pnma to cubic upon heating, unlike measurements that reported the occurrence of an intermediate long‐range‐tilted tetragonal P4/mbm phase in‐between the orthorhombic and cubic phases. Such disagreement, which may cast some doubts about the extent to which first‐principle methods can be trusted to mimic hybrid perovskites, can be resolved by “only” changing one short‐range tilting parameter in the whole set of effective Hamiltonian coefficients. In such a case, some reasonable values of this specific parameter result in the predictions that i) the intermediate P4/mbm state originates from fluctuations over many different tilted states; and ii) the cubic phase is highly locally distorted and develops strong transverse antiphase correlation between first‐nearest neighbor iodine octahedral tiltings, before undergoing a phase transition to P4/mbm under cooling. 相似文献
23.
伏彩萍 《有色金属(冶炼部分)》2020,(6):66-69
针对现有柠檬酸铋制备工艺合成时间长、能耗高、产品纯度不高等不足,介绍了一种常温下制备柠檬酸铋的新工艺。新工艺制备时间短,制备的柠檬酸铋产品质量好,合成过程产生的废水可循环利用,废气经碱液循环吸收可生产硝酸钠副产品。 相似文献
24.
Rui ZHAO Weikai LI Tian WANG Ke ZHAN Zheng YANG Ya YAN Bin ZHAO Junhe YANG 《材料科学前沿(英文版)》2020,14(2):188
Effective thermal management of electronic integrated devices with high powder density has become a serious issue, which requires materials with high thermal conductivity (TC). In order to solve the problem of weak bonding between graphite and Cu, a novel Cu/graphite film/Cu sandwich composite (Cu/GF/Cu composite) with ultrahigh TC was fabricated by electro-deposition. The micro-riveting structure was introduced to enhance the bonding strength between graphite film and deposited Cu layers by preparing a rectangular array of micro-holes on the graphite film before electro-deposition. TC and mechanical properties of the composites with different graphite volume fractions and current densities were investigated. The results showed that the TC enhancement generated by the micro-riveting structure for Cu/GF/Cu composites at low graphite content was more effective than that at high graphite content, and the strong texture orientation of deposited Cu resulted in high TC. Under the optimizing preparing condition, the highest in-plane TC reached 824.3 W·m−1·K−1, while the ultimate tensile strength of this composite was about four times higher than that of the graphite film. 相似文献
25.
26.
27.
Yuanyuan Zhang Haiyan Lu Bing Wang Zhuo Zhang Xiaorong Lin Zhongzheng Chen Bin Li 《International Journal of Food Science & Technology》2015,50(6):1397-1404
Removal of imidacloprid and acetamiprid in tea infusions by microfiltration membrane using dead‐end model was investigated in the present study. The results showed that microfiltration significantly promoted the removal of both pesticides (P < 0.05) in tea infusions. Furthermore, the extent of removal was strongly influenced by the pore size of membrane, operational pressure and the concentrations of tea infusions. The initial concentration of imidacloprid and acetamiprid showed no significant effect on their removal rates. The maximum removal rates were 79.7% for imidacloprid and 81.9% acetamiprid. The changes in major chemical components of tea infusions after microfiltration were evaluated. The results indicated that microfiltration caused no considerable changes in total polyphenols and total free amino acids, and small but statistically significant losses (6.3–18.0%) of eight catechins and three methylxanthines when filtration volume reached to 200 mL. The present study validated the application of microfiltration as a potentially feasible and promising method for the removal of imidacloprid and acetamiprid residues from tea infusions. 相似文献
28.
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
29.
Qiaozhi Zhang Yanbo Wang Linglin Fu 《Comprehensive Reviews in Food Science and Food Safety》2020,19(5):2559-2587
Dietary advanced glycation end products (dAGEs) are complex and heterogeneous compounds derived from nonenzymatic glycation reactions during industrial processing and home cooking. There is mounting evidence showing that dAGEs are closely associated with various chronic diseases, where the absorbed dAGEs fuel the biological AGEs pool to exhibit noxious effects on human health. Currently, due to the uncertain bioavailability and rapid renal clearance of dAGEs, the relationship between dAGEs and biological AGEs remains debatable. In this review, we provide the most updated information on dAGEs including their generation in processed foods, analytical and characterization techniques, metabolic fates, interaction with AGE receptors, implications on human health and reducing strategies. Available evidence demonstrating a relevance between dAGEs and food allergy is also included. AGEs are ubiquitous in foods and their contents largely depend on the reactivity of carbonyl and amino groups, along with surrounding condition mainly pH and heating procedures. Once being digested and absorbed into the circulation, two separate pathways can be involved in the deleterious effects of dAGEs: an AGE receptor‐dependent way to stimulate cell signals, and an AGE receptor‐independent way to dysregulate proteins via forming complexes. Inhibition of AGEs formation during food processing and reduction in the diet are two potent approaches to restrict health‐hazardous dAGEs. To elucidate the biological role of dAGEs toward human health, the following significant perspectives are raised: molecular size and complexity of dAGEs; interactions between unabsorbed dAGEs and gut microbiota; and roles played by concomitant compounds in the heat‐processed foods. 相似文献
30.
双检合并技术在海底电缆地震资料处理中被广泛应用,可衰减电缆鬼波的影响。传统方式以水、陆检记录的波场记录相同为假设,电缆鬼波压制效果差,合并效果并不理想。在分析交叉鬼波化双检合并技术基本原理的基础上,综合利用水检资料与陆检鬼波褶积的结果和陆检资料与水检鬼波褶积的结果求取刻度算子,同时在地震资料处理中利用陆检资料标定水检资料,从而优化了交叉鬼波化双检合并技术。实际资料处理结果表明,改进后的技术可有效衰减电缆鬼波,分离出上行波场,大幅度拓宽地震资料频带,提高地震资料分辨率,从而提供更丰富的构造细节信息。 相似文献