全文获取类型
收费全文 | 38221篇 |
免费 | 3982篇 |
国内免费 | 3170篇 |
专业分类
电工技术 | 1090篇 |
技术理论 | 1篇 |
综合类 | 3946篇 |
化学工业 | 6314篇 |
金属工艺 | 1315篇 |
机械仪表 | 583篇 |
建筑科学 | 10825篇 |
矿业工程 | 2034篇 |
能源动力 | 909篇 |
轻工业 | 5497篇 |
水利工程 | 3510篇 |
石油天然气 | 1474篇 |
武器工业 | 73篇 |
无线电 | 932篇 |
一般工业技术 | 1996篇 |
冶金工业 | 1946篇 |
原子能技术 | 268篇 |
自动化技术 | 2660篇 |
出版年
2024年 | 89篇 |
2023年 | 467篇 |
2022年 | 1004篇 |
2021年 | 1227篇 |
2020年 | 1247篇 |
2019年 | 1165篇 |
2018年 | 1119篇 |
2017年 | 1341篇 |
2016年 | 1464篇 |
2015年 | 1472篇 |
2014年 | 2534篇 |
2013年 | 2439篇 |
2012年 | 2918篇 |
2011年 | 3020篇 |
2010年 | 2327篇 |
2009年 | 2287篇 |
2008年 | 1994篇 |
2007年 | 2599篇 |
2006年 | 2315篇 |
2005年 | 2148篇 |
2004年 | 1907篇 |
2003年 | 1541篇 |
2002年 | 1166篇 |
2001年 | 947篇 |
2000年 | 864篇 |
1999年 | 672篇 |
1998年 | 529篇 |
1997年 | 417篇 |
1996年 | 364篇 |
1995年 | 355篇 |
1994年 | 276篇 |
1993年 | 197篇 |
1992年 | 172篇 |
1991年 | 132篇 |
1990年 | 102篇 |
1989年 | 89篇 |
1988年 | 75篇 |
1987年 | 65篇 |
1986年 | 66篇 |
1985年 | 47篇 |
1984年 | 37篇 |
1983年 | 17篇 |
1982年 | 26篇 |
1981年 | 24篇 |
1980年 | 19篇 |
1979年 | 41篇 |
1977年 | 4篇 |
1964年 | 4篇 |
1959年 | 5篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
81.
Anna Rita Bavaro Mariaelena Di Biase Amalia Conte Stella Lisa Lonigro Leonardo Caputo Annamaria Cedola Matteo Alessandro Del Nobile Antonio Francesco Logrieco Paola Lavermicocca Francesca Valerio 《International Journal of Food Science & Technology》2021,56(7):3197-3208
Production of the traditional Italian Focaccia bread (FcBread) requires reformulation to meet the new rules for healthier foods. We tested the applicability of a short-fermented (15 h) liquid sourdough (LS) (dough yield, DY, 250), obtained using quinoa (Q) or amaranth (Am) flour fermented with a Weissella cibaria strain (C43-11) producing exopolysaccharides (EPS) as fat replacer in yeast-leavened FcBread. The LSs were applied during the FcBread-making process at industrial pilot plant, reducing the added fat amount by 20% (FcBread-QLS and FcBread-AmLS) and products were compared with reference samples not containing EPS. All the products were analysed for physico-chemical properties (pH, TTA, organic acids, protein content and profile, instrumental colour), textural properties, sensory quality and glycemic index. The application of both pseudo-cereal-based W. cibaria LSs in FcBread allowed obtaining products with a reduced amount of fat, increased protein amount, mainly due to the albumin and glutenin/glutelin fractions, reduced glycemic index, improved texture and preserved in the traditional sensory profile of ‘focaccia’. 相似文献
82.
通过在6198采煤工作面现场施工煤层注水钻孔采取煤样,实验室试验注水钻孔水压力分布、煤样含水率变化,得到了工作面煤层注水影响半径等技术参数,为采煤工作面煤层注水提供了一定的参考依据。 相似文献
83.
《岩石力学与岩土工程学报(英文版)》2020,12(3):630-641
Structure is an evident determinant for macroscopic behaviors of soils. However, this is not taken into account in most constitutive models, as structure is a rather complex issue in models. For this, it is important to develop and implement simple models that can reflect this important aspect of soil behavior. This paper tried to model structured soils based on well-established concepts, such as critical state and sub-loading. Critical state is the core of the classic Cam Clay model. The sub-loading concept implies adoption of an inner (sub-loading) yield surface, according to specific hardening rules for some internal strain-like state variables. Nakai and co-workers proposed such internal variables for controlling density (ρ) and structure (ω), using a modified stress space, called tij. Herein, similar variables are used in the context of the better-known invariants (p and q) of the Cam Clay model. This change requires explicit adoption of a non-associated flow rule for the sub-loading surface. This is accomplished by modifying the dilatancy ratio of the Cam Clay model, as a function of the new internal variables. These modifications are described and implemented under three-dimensional (3D) conditions. The model is then applied to simulating laboratory tests under different stress paths and the results are compared to experiments reported for different types of structured soils. The good agreements show the capacity and potential of the proposed model. 相似文献
84.
通过对于都县黄麟-祁禄山地区开展1:5万土地质量地球化学调查,在野外土壤样品采集和化验测试的基础上,系统地研究了影响土地质量的各项地球化学指标特征与控制因素,基本查明有益元素、重金属元素分布,划分出重点污染区和绿色土地发展区,并进行土地质量等级评价,为永久基本农田建设、土地资源开发与利用等方面提出建议。 相似文献
85.
Qiang Liu Wenchuan Guo Xinhua Zhu 《International Journal of Food Science & Technology》2018,53(9):2037-2044
Dielectric properties (dielectric constant ε′ and dielectric loss factor ε′′) of whole milk and skim milk with the lactose content of 4.56–6.44% and 4.57–6.47%, respectively, were measured over the frequency range of 20–4500 MHz at 25 °C using a vector network analyzer. The results showed that ε′ decreased with increasing frequency, and ε′′ changed with V shape and its minimum was noted at about 2000 MHz. Whole milk had lower dielectric properties than skim milk at almost same lactose content and a given frequency. ε′ had weak positive linear relationship with lactose content for whole milk, but had negative linear relationship for skim milk. No matter for which milk, ε′′ had very good negative linear relationship with lactose content below 1000 MHz and had good positive linear relationship above 2300 MHz. The study provides information on developing rapid lactose detector for milk in future. 相似文献
86.
为探究大水矿山充填体的力学性能变化,将充填体试块置入高压水体中使其内部形成孔隙水压,研究孔隙水压下充填体的抗压强度、抗拉强度和含水量等指标的变化。试验以孔隙水压、浸入时间、充填配比和料浆浓度为主要影响因素,开展29组充填体强度试验。方差分析表明,料浆浓度和充填配比对充填体抗压强度影响极显著,孔隙水压影响显著;浸入时间对充填抗拉强度影响显著。相同充填配比和料浆浓度下的充填体抗压和抗拉强度随孔隙水压和浸入时间增长而下降,其中抗拉强度下降幅度较大。充填体含水量随孔隙水压增大而增大,增长趋势和充填体强度增大趋势相吻合。 相似文献
87.
88.
AbstractComfort has been one of the most important features of clothing, particularly for sportswear, which requires an effective transport of heat and moisture from the inner to the outer side of clothing. We herein report the use of a simple technique of spray coating and commercially available water repellents for a one-sided hydrophobic and self-initiated one-way water transport cotton fabric. The highlight of this work is the simplicity of the process and choice of chemicals that can be adopted easily by any textile finishing industry. On this fabric, water was able to diffuse and penetrate the fabric structure in one direction from the hydrophobic to the hydrophilic side but was unable to go the opposite direction. The directional transport improved with smaller droplets and lower add-on achievable by higher air pressure and longer distance of spray coating. From moisture management tests, the best result was obtained with the spray coating of Phobol NB-NH at an air pressure of 3.0?kgf/cm2 and a distance of 120?cm. Phobol NB-NH gave better result of transport and overall comfort properties than Phobotex RSY. 相似文献
89.
摘 要: 目的 建立高效液相色谱法测定磷脂酰丝氨酸。方法 样品经过正己烷:异丙醇(25:75, V:V)溶解, 以正己烷:异丙醇:1%磷酸水溶液=(25:70:5, V:V:V)为流动相, 等度洗脱, 经SIL 色谱柱(4.6 mm×250 mm,5 μm)分离, 并于205 nm波长检测。结果 磷脂酰丝氨酸在浓度0.13504~0.67520 mg/mL之间呈现良好的线性关系, r=0.9993, 平均回收率为96.16%~99.60%, 相对标准偏差为1.1%。结论 该方法测定保健食品中磷脂酰丝氨酸含量具专属性强, 耗时短、操作简便、准确、重现性好,可在实验室推广。 相似文献
90.
通过于都县黄麟地区1:5万土地质量地球化学调查,基本査明该地区农作物中硒元素及其他元素的地球化学特征,综合分析岀绿色富硒土壤分布,并优选出绿色富硒地块,为特色农产品基地建设的开发与利用提供理论依据。 相似文献