全文获取类型
收费全文 | 36143篇 |
免费 | 4182篇 |
国内免费 | 2012篇 |
学科分类
工业技术 | 42337篇 |
出版年
2024年 | 107篇 |
2023年 | 540篇 |
2022年 | 1053篇 |
2021年 | 1276篇 |
2020年 | 1322篇 |
2019年 | 1073篇 |
2018年 | 1057篇 |
2017年 | 1128篇 |
2016年 | 1453篇 |
2015年 | 1515篇 |
2014年 | 2557篇 |
2013年 | 2234篇 |
2012年 | 2965篇 |
2011年 | 3034篇 |
2010年 | 2196篇 |
2009年 | 2274篇 |
2008年 | 2049篇 |
2007年 | 2461篇 |
2006年 | 2152篇 |
2005年 | 1896篇 |
2004年 | 1531篇 |
2003年 | 1277篇 |
2002年 | 920篇 |
2001年 | 822篇 |
2000年 | 616篇 |
1999年 | 528篇 |
1998年 | 386篇 |
1997年 | 376篇 |
1996年 | 299篇 |
1995年 | 254篇 |
1994年 | 197篇 |
1993年 | 153篇 |
1992年 | 99篇 |
1991年 | 93篇 |
1990年 | 60篇 |
1989年 | 76篇 |
1988年 | 32篇 |
1987年 | 28篇 |
1986年 | 28篇 |
1985年 | 21篇 |
1984年 | 27篇 |
1983年 | 28篇 |
1982年 | 15篇 |
1981年 | 13篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1977年 | 8篇 |
1975年 | 9篇 |
1963年 | 7篇 |
1959年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
乳腺疾病已严重危害女性身心健康,其中乳腺癌更位居全球范围内女性癌症发病率和死亡率首位,因此乳腺癌的早期发现意义重大。传统结构影像学早期检测疾病具有一定局限性,而红外热成像作为功能成像技术可为乳腺癌的早期筛查提供有效线索。因此本文主要就红外热成像在乳腺疾病的早期检测及预后评估的应用价值进行综述。 相似文献
62.
63.
The network reconfiguration is an important stage of restoring a power system after a complete blackout or a local outage. Reasonable planning of the network reconfiguration procedure is essential for rapidly restoring the power system concerned. An approach for evaluating the importance of a line is first proposed based on the line contraction concept. Then, the interpretative structural modeling (ISM) is employed to analyze the relationship among the factors having impacts on the network reconfiguration. The security and speediness of restoring generating units are considered with priority, and a method is next proposed to select the generating unit to be restored by maximizing the restoration benefit with both the generation capacity of the restored generating unit and the importance of the line in the restoration path considered. Both the start-up sequence of generating units and the related restoration paths are optimized together in the proposed method, and in this way the shortcomings of separately solving these two issues in the existing methods are avoided. Finally, the New England 10-unit 39-bus power system and the Guangdong power system in South China are employed to demonstrate the basic features of the proposed method. 相似文献
64.
65.
Sensory characteristics and storage quality indicators of surimi franks nutritionally enhanced with omega‐3 rich flaxseed oil and salmon oil 下载免费PDF全文
Christin Sell Sarah Beamer Jacek Jaczynski Kristen E. Matak 《International Journal of Food Science & Technology》2015,50(1):210-217
Surimi franks were fortified with flaxseed or salmon oil at 2 g/100 g sample, franks without added oil served as a control. Thiobarbituric acid reactive substances values were highest (P < 0.001) in salmon oil franks; however, these values did not change over the 21‐day storage period regardless of frank type (P > 0.05). Frank pH decreased over time (P = 0.011) for all frank types. There were differences in textural properties between frank types (P < 0.05), with the flaxseed franks being softer and less gummy, cohesive and chewy than the control franks. Participants (n = 79; age 18–35) evaluated visual appeal, colour, aroma, texture, flavour and acceptability on a hedonic scale; there were no differences (P > 0.05) between franks. Fifty‐four panellists reported consuming sausage on a weekly to monthly basis, and most (50/79) indicated interest in purchasing this type product. The surimi franks were accepted by young adult consumers, which may indicate market potential of these types of products. 相似文献
66.
This article theoretically and empirically analyzes backtesting portfolio value-at-risk (VaR) with estimation risk in an intrinsically multi-variate framework. It particularly takes into account the estimation of portfolio weights in forecasting portfolio VaR and its impact on backtesting. It shows that the estimation risk from estimating portfolio weights and that from estimating the multi-variate dynamic model make the existing methods in a univariate framework inapplicable. It proposes a general theory to quantify estimation risk applicable to the present problem and suggests practitioners a simple but effective way to implement valid inference to overcome the effect of estimation risk in backtesting portfolio VaR. In particular, we apply our theory to the efficient mean-variance-skewness portfolio for a multi-variate generalized autoregressive conditional heteroscedasticity model with multi-variate general hyperbolic distributed innovations. Some Monte Carlo simulations and an empirical application demonstrate the merits of our method. 相似文献
67.
针对高校基建项目的特点,界定了高校基建项目管理后评价的内涵。运用层次分析法,构建了完整的项目管理后评价指标体系。以某高校综合实验楼为例,在全面收集项目相关资料和对相关专家广泛咨询的基础上,通过对各评价指标的单排序和总排序计算分析及其一致性检验,得到各影响因素的量化综合评价结果。在此基础上,对项目管理全过程进行后评价,以反馈形式为同类公益性基建项目管理提供参考。 相似文献
68.
通过分析激光源的类型和结构,建立参数数据库,并结合机器人运动的动力学分析,本研究提出了汽车总装线上远程激光焊接(RLW)的能量评估模型。通过对简单焊件进行焊接实验,将传统激光焊接和远程激光焊接进行了对比,结果发现,焊接过程中机器人运动能量逐渐减少,而激光能量逐渐增加。处理时间和激光功率是影响远程焊接能源效率的主要因素。 相似文献
69.
70.
The development of piezospectroscopic (PS) composites has enabled the creation of a non-destructive evaluation (NDE) technique which integrates piezospectroscopy, digital image correlation (DIC) and analytical multi-scale mechanics to map the elastic modulus of a coated material. The measured elastic modulus was represented as a normal distribution with a mean value (32.2 GPa) which is within 8% of the conventionally recorded modulus (35 GPa). Damage mechanics are applied to map elastic degradation in situ mechanical loading with an average uncertainty (~10 GPa) that was sufficient in observing subsurface, progressive damage patterns which are unique to the coated material. 相似文献