全文获取类型
收费全文 | 80222篇 |
免费 | 8958篇 |
国内免费 | 5625篇 |
专业分类
电工技术 | 8975篇 |
技术理论 | 3篇 |
综合类 | 9026篇 |
化学工业 | 8769篇 |
金属工艺 | 2218篇 |
机械仪表 | 3350篇 |
建筑科学 | 9248篇 |
矿业工程 | 3957篇 |
能源动力 | 2540篇 |
轻工业 | 9382篇 |
水利工程 | 4384篇 |
石油天然气 | 5912篇 |
武器工业 | 1235篇 |
无线电 | 4359篇 |
一般工业技术 | 6167篇 |
冶金工业 | 2234篇 |
原子能技术 | 554篇 |
自动化技术 | 12492篇 |
出版年
2024年 | 506篇 |
2023年 | 1470篇 |
2022年 | 2306篇 |
2021年 | 2806篇 |
2020年 | 3105篇 |
2019年 | 2768篇 |
2018年 | 2633篇 |
2017年 | 2825篇 |
2016年 | 3236篇 |
2015年 | 3361篇 |
2014年 | 5096篇 |
2013年 | 5059篇 |
2012年 | 5894篇 |
2011年 | 6220篇 |
2010年 | 4529篇 |
2009年 | 4897篇 |
2008年 | 4428篇 |
2007年 | 5272篇 |
2006年 | 4634篇 |
2005年 | 4042篇 |
2004年 | 3359篇 |
2003年 | 2735篇 |
2002年 | 2141篇 |
2001年 | 1871篇 |
2000年 | 1594篇 |
1999年 | 1468篇 |
1998年 | 1120篇 |
1997年 | 997篇 |
1996年 | 849篇 |
1995年 | 691篇 |
1994年 | 590篇 |
1993年 | 475篇 |
1992年 | 411篇 |
1991年 | 292篇 |
1990年 | 191篇 |
1989年 | 190篇 |
1988年 | 111篇 |
1987年 | 88篇 |
1986年 | 74篇 |
1985年 | 49篇 |
1984年 | 73篇 |
1983年 | 64篇 |
1982年 | 52篇 |
1981年 | 27篇 |
1980年 | 23篇 |
1979年 | 29篇 |
1978年 | 20篇 |
1977年 | 15篇 |
1975年 | 10篇 |
1951年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
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
2.
电网的安全水平主要取决于其使用产品的质量是否过关。如果产品的质量较好,则能建造出优质的电网,电网的安全水平便会随之提高。因此,应加强对产品质量的监督管理,从而提高电网的安全水平。我们可建立质量监督管理系统,及时抽检出质量不过关的产品,从而消除电网运行过程中潜在的安全隐患。 相似文献
3.
Goat milk has specific chemical composition and physical properties. The purpose of this study was to investigate the change of milk quality and emulsion stability during 60 d frozen storage. Milk sample was taken from three Ettawah Crossedbred goats that were divided into three groups. Samples were frozen and stored for 0, 30 and 60 days. At the end of each storage periode, milk sample was thawed in the refrigerator and analyzed for total number of bacteria, chemical (acidity, pH, free fatty acids), physical (alcohol test, clot on boiling test) quality, and emulsion stability. The microbiological and chemical data were analyzed statistically using one way ANOVA, whereas physical quality and emulsion stabilty were expressed qualitatively. There were no change in the total bacteria, acidity, pH and free fatty acid (FFA) of milk during storage, whereas the assessment by 70% alcohol showed positive since 0 d. Emulsions stability changed after 30 d of storage. While, the clot on boiling (COB) test of milk was positive at 60 d of storage. Recommendation is frozen storage of goat milk should not longer than 30 d. 相似文献
4.
Anis Zeglaoui Anouar Houmia Maher Mejai Radhouane Aloui 《International Journal of Adaptive Control and Signal Processing》2021,35(9):1842-1859
In compressive sampling theory, the least absolute shrinkage and selection operator (LASSO) is a representative problem. Nevertheless, the non-differentiable constraint impedes the use of Lagrange programming neural networks (LPNNs). We present in this article the -LPNN model, a novel algorithm that tackles the LASSO minimization together with the underlying theory support. First, we design a sequence of smooth constrained optimization problems, by introducing a convenient differentiable approximation to the non-differentiable -norm constraint. Next, we prove that the optimal solutions of the regularized intermediate problems converge to the optimal sparse signal for the LASSO. Then, for every regularized problem from the sequence, the -LPNN dynamic model is derived, and the asymptotic stability of its equilibrium state is established as well. Finally, numerical simulations are carried out to compare the performance of the proposed -LPNN algorithm with both the LASSO-LPNN model and a standard digital method. 相似文献
5.
Hashim A.
Hashim 《国际强度与非线性控制杂志
》2020,30(10):3848-3870
》2020,30(10):3848-3870
This paper introduces two novel nonlinear stochastic attitude estimators developed on the Special Orthogonal Group with the tracking error of the normalized Euclidean distance meeting predefined transient and steady‐state characteristics. The tracking error is confined to initially start within a predetermined large set such that the transient performance is guaranteed to obey dynamically reducing boundaries and decrease smoothly and asymptotically to the origin in probability from almost any initial condition. The proposed estimators produce accurate attitude estimates with remarkable convergence properties using measurements obtained from low‐cost inertial measurement units. The estimators proposed in continuous form are complemented by their discrete versions for the implementation purposes. The simulation results illustrate the effectiveness and robustness of the proposed estimators against uncertain measurements and large initialization error, whether in continuous or discrete form. 相似文献
6.
7.
8.
孙洪松 《石油化工管理干部学院学报》2006,(1):52-55
目前,我国股票市场上的股票评级尚处于探索阶段,评级时多采用专家法或历史法,而对于影响股票评级的各因素的确定以及因素间的相互作用缺乏定量分析。研究将结构模型应用到我国股票市场的股票评级中,建立关于我国股票评级的财务结构模型;分析各个因素对股票评级的影响;建立股票评级经验模式值。 相似文献
9.
10.
高抗挤厚壁套管的性能及应用效果评价 总被引:1,自引:1,他引:0
中原油田套管损坏的主要原因是现有套管强度不够,无法抵抗盐膏层段的巨大外挤力。开发了TP130TT型高抗挤厚壁套管,其强度能很好地抵抗盐膏层巨大外挤力。实验室试验表明,各项性能指标达到了设计要求,现场使用取得了很好的效果,解决了中原油田盐膏层段套管强度不足的难题。 相似文献