全文获取类型
收费全文 | 356479篇 |
免费 | 32261篇 |
国内免费 | 17255篇 |
学科分类
工业技术 | 405995篇 |
出版年
2024年 | 704篇 |
2023年 | 5250篇 |
2022年 | 9362篇 |
2021年 | 14126篇 |
2020年 | 10666篇 |
2019年 | 8615篇 |
2018年 | 9640篇 |
2017年 | 11163篇 |
2016年 | 10059篇 |
2015年 | 14131篇 |
2014年 | 18239篇 |
2013年 | 22649篇 |
2012年 | 24627篇 |
2011年 | 26714篇 |
2010年 | 23696篇 |
2009年 | 22848篇 |
2008年 | 22143篇 |
2007年 | 21134篇 |
2006年 | 20483篇 |
2005年 | 17112篇 |
2004年 | 11829篇 |
2003年 | 10234篇 |
2002年 | 9521篇 |
2001年 | 8486篇 |
2000年 | 7716篇 |
1999年 | 7783篇 |
1998年 | 6616篇 |
1997年 | 5420篇 |
1996年 | 4941篇 |
1995年 | 4229篇 |
1994年 | 3522篇 |
1993年 | 2652篇 |
1992年 | 2060篇 |
1991年 | 1536篇 |
1990年 | 1223篇 |
1989年 | 1058篇 |
1988年 | 798篇 |
1987年 | 569篇 |
1986年 | 450篇 |
1985年 | 351篇 |
1984年 | 228篇 |
1983年 | 202篇 |
1982年 | 183篇 |
1981年 | 175篇 |
1980年 | 168篇 |
1979年 | 120篇 |
1978年 | 72篇 |
1977年 | 72篇 |
1976年 | 86篇 |
1975年 | 46篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
Fangqing Wei Xiaoqi Zhang Jiayun Song Feng Yang 《International Transactions in Operational Research》2023,30(1):369-393
Evaluating the efficiency of healthcare services accurately can help in analyzing the rationality of inputs and outputs in such services. Considering the consistency and equity of assessment criteria, this study conducts the stochastic multicriteria acceptability analysis (SMAA-2) with a directional distance function to evaluate the efficiency of healthcare services in 31 provincial administrative regions of mainland China, as observed in 2018. We use SMAA-DDF to explore all the projection directions to the efficient frontier instead of a certain projection direction. We measure the maximum and average efficiencies for each of the 31 provincial healthcare services. Our empirical findings show that only seven provinces achieve optimal healthcare service efficiency; the eastern area performed the best, followed by the central, western, and northeast areas. Furthermore, the path along the projection directions is provided to help inefficient provinces improve their efficiency and obtain the best possible positions. 相似文献
63.
64.
Yang Hu Stephanie M. Sjoberg Chunpen Chen Amber L. Hauvermale Craig F. Morris Stephen R. Delwiche Ashley E. Cannon Camille M. Steber Zhiwu Zhang 《Comprehensive Reviews in Food Science and Food Safety》2022,21(3):2105-2117
This review examines the application, limitations, and potential alternatives to the Hagberg–Perten falling number (FN) method used in the global wheat industry for detecting the risk of poor end-product quality mainly due to starch degradation by the enzyme α-amylase. By viscometry, the FN test indirectly detects the presence of α-amylase, the primary enzyme that digests starch. Elevated α-amylase results in low FN and damages wheat product quality resulting in cakes that fall, and sticky bread and noodles. Low FN can occur from preharvest sprouting (PHS) and late maturity α-amylase (LMA). Moist or rainy conditions before harvest cause PHS on the mother plant. Continuously cool or fluctuating temperatures during the grain filling stage cause LMA. Due to the expression of additional hydrolytic enzymes, PHS has a stronger negative impact than LMA. Wheat grain with low FN/high α-amylase results in serious losses for farmers, traders, millers, and bakers worldwide. Although blending of low FN grain with sound wheat may be used as a means of moving affected grain through the marketplace, care must be taken to avoid grain lots from falling below contract-specified FN. A large amount of sound wheat can be ruined if mixed with a small amount of sprouted wheat. The FN method is widely employed to detect α-amylase after harvest. However, it has several limitations, including sampling variability, high cost, labor intensiveness, the destructive nature of the test, and an inability to differentiate between LMA and PHS. Faster, cheaper, and more accurate alternatives could improve breeding for resistance to PHS and LMA and could preserve the value of wheat grain by avoiding inadvertent mixing of high- and low-FN grain by enabling testing at more stages of the value stream including at harvest, delivery, transport, storage, and milling. Alternatives to the FN method explored here include the Rapid Visco Analyzer, enzyme assays, immunoassays, near-infrared spectroscopy, and hyperspectral imaging. 相似文献
65.
66.
67.
Virtual Reality - BRICKxAR is a novel augmented reality (AR) instruction method for construction toys such as LEGO®. With BRICKxAR, physical LEGO construction is guided by virtual bricks.... 相似文献
68.
Neural Processing Letters - Semi-supervised learning techniques have been attracting increasing interests in many machine learning fields for its effectiveness in using labeled and unlabeled... 相似文献
69.
Xiao Chen Minlan Yuan Yuting Wang Yan Zhou Xiaohong Sun 《International Journal of Food Science & Technology》2022,57(5):2670-2679
The present study aimed to evaluate the effect of fermentation and gastrointestinal digestion of three kinds of fermented kiwifruit pulps with different Lactobacillus (Lactobacillus plantarum, Lactobacillus acidophilus and Lactobacillus casei). The changes in bioactive substances (total phenolic acid, total flavonoid, vitamin C and the viable count), antioxidant capacity (DPPH, ABTS, hydroxyl radical and superoxide anion radical scavenging activity) and phenolic profiles (protocatechuic acid, protocatechualdehyde, chlorogenic acid, caffeic acid and p-coumaric acid) were detected. The result showed, compared to non-fermented kiwifruit pulp, fermentation with LP and LA had higher content of TPA, TF and VC, as well as antioxidant capacity. Fermentation with LP and the content of protocatechualdehyde, p-coumaric acid and chlorogenic acid were increased. However, after digestion, LP showed more effect in maintaining the content of antioxidants, antioxidant capacity and the viable count rather than LA. During digestion, the content of protocatechualdehyde and p-coumaric acid was increased in fermented samples compared with non-fermented samples. Overall, compared with LA and LC, LP is more suitable for the fermentation of kiwifruit pulp. 相似文献
70.
Baohua Yuan Lili Wei Lixia Yang Liangjiu Bai Huawei Yang Donglei Wei Feng Wang Wenxiang Wang Hou Chen 《Journal of the American Ceramic Society》2022,105(2):801-805
Solar steam generation has attracted considerable interest due to its easy accessibility and sustainability. However, dye molecules were gradually concentrated on bulk water or the surface of solar absorbers during the disposal of dye wastewater. Herein, LaB6/g-C3N4 composites were immobilized on porous cotton cloth, served as a solar absorber resistant to dye clogging. The optimal solar absorber possessed solar harvesting of 92.3% and showed great application potential in the field of the treatment of dye wastewater. This study presented a new approach for the treatment of dye wastewater. 相似文献