全文获取类型
收费全文 | 61967篇 |
免费 | 6606篇 |
国内免费 | 5086篇 |
学科分类
工业技术 | 73659篇 |
出版年
2024年 | 349篇 |
2023年 | 1081篇 |
2022年 | 1738篇 |
2021年 | 2094篇 |
2020年 | 2379篇 |
2019年 | 2186篇 |
2018年 | 2093篇 |
2017年 | 2225篇 |
2016年 | 2434篇 |
2015年 | 2503篇 |
2014年 | 3772篇 |
2013年 | 3850篇 |
2012年 | 4471篇 |
2011年 | 4867篇 |
2010年 | 3549篇 |
2009年 | 3897篇 |
2008年 | 3478篇 |
2007年 | 4048篇 |
2006年 | 3564篇 |
2005年 | 3154篇 |
2004年 | 2621篇 |
2003年 | 2170篇 |
2002年 | 1740篇 |
2001年 | 1483篇 |
2000年 | 1294篇 |
1999年 | 1220篇 |
1998年 | 957篇 |
1997年 | 814篇 |
1996年 | 666篇 |
1995年 | 548篇 |
1994年 | 523篇 |
1993年 | 396篇 |
1992年 | 392篇 |
1991年 | 251篇 |
1990年 | 179篇 |
1989年 | 150篇 |
1988年 | 92篇 |
1987年 | 68篇 |
1986年 | 51篇 |
1985年 | 31篇 |
1984年 | 49篇 |
1983年 | 40篇 |
1982年 | 37篇 |
1981年 | 17篇 |
1980年 | 48篇 |
1979年 | 31篇 |
1978年 | 11篇 |
1977年 | 7篇 |
1959年 | 5篇 |
1951年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 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.
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
3.
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
4.
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
5.
6.
7.
岩石物理横波速度曲线计算技术 总被引:15,自引:3,他引:12
横波速度是地震勘探中的重要参数。针对实际生产中缺乏横波速度测井曲线资料,利用经验公式计算精确度不高的问题,通过对横波速度计算理论模型的研究分析,选择Blot-Gassman模型法,利用岩石矿物成分、流体成分、孔隙度及密度等测井曲线进行横波速度测井曲线的计算,并对横波速度计算技术和流程进行研究。在实际工区进行了横波速度曲线计算,计算结果与实测横波吻合程度较高,误差小于10%,该技术在储层和流体识别预测的应用中取得了较好效果。 相似文献
8.
吐哈油田部分区块地层压力系数小于0.9,常规水基压井液对储层伤害大,若使用油基压井液成本高,环境污染严重。通过实验优选出了一种低密度水基微泡沫压井液。该压井液具有密度低、泡沫强度高、稳定性好、携砂能力强等优点。现场应用表明,低密度微泡沫压井液稳定时间大于48 h,密度在0.70~0.99 g/cm3之间可调,抗油污染能力强,抗油大于8%,抗温在100℃以上,岩心污染后渗透率恢复值大于80%;并且施工方便,成本低,具有储层保护能力,使用微泡沫压井液的井表皮系数在0.20~2.34之间。 相似文献
9.
10.
模袋混凝土护坡是一种新型的护面技术,具有整体性强、冲灌的混凝土强度可根据工程具体要求设计的优点.它克服了其它护面型式的诸多缺点,成为十分成熟的护面新技术.随着土工合成材料在水利工程上大面积推广应用,模袋混凝土护坡具有良好的应用前景. 相似文献