全文获取类型
收费全文 | 27061篇 |
免费 | 961篇 |
国内免费 | 54篇 |
专业分类
电工技术 | 324篇 |
综合类 | 37篇 |
化学工业 | 5447篇 |
金属工艺 | 601篇 |
机械仪表 | 503篇 |
建筑科学 | 1415篇 |
矿业工程 | 155篇 |
能源动力 | 800篇 |
轻工业 | 2419篇 |
水利工程 | 274篇 |
石油天然气 | 106篇 |
无线电 | 1945篇 |
一般工业技术 | 4500篇 |
冶金工业 | 5500篇 |
原子能技术 | 209篇 |
自动化技术 | 3841篇 |
出版年
2022年 | 289篇 |
2021年 | 447篇 |
2020年 | 330篇 |
2019年 | 367篇 |
2018年 | 466篇 |
2017年 | 482篇 |
2016年 | 532篇 |
2015年 | 441篇 |
2014年 | 672篇 |
2013年 | 1645篇 |
2012年 | 1096篇 |
2011年 | 1509篇 |
2010年 | 1076篇 |
2009年 | 1125篇 |
2008年 | 1282篇 |
2007年 | 1212篇 |
2006年 | 1061篇 |
2005年 | 999篇 |
2004年 | 823篇 |
2003年 | 774篇 |
2002年 | 729篇 |
2001年 | 478篇 |
2000年 | 441篇 |
1999年 | 468篇 |
1998年 | 471篇 |
1997年 | 415篇 |
1996年 | 436篇 |
1995年 | 439篇 |
1994年 | 415篇 |
1993年 | 381篇 |
1992年 | 388篇 |
1991年 | 248篇 |
1990年 | 338篇 |
1989年 | 322篇 |
1988年 | 281篇 |
1987年 | 276篇 |
1986年 | 272篇 |
1985年 | 332篇 |
1984年 | 329篇 |
1983年 | 276篇 |
1982年 | 298篇 |
1981年 | 291篇 |
1980年 | 230篇 |
1979年 | 285篇 |
1978年 | 240篇 |
1977年 | 218篇 |
1976年 | 245篇 |
1975年 | 206篇 |
1974年 | 192篇 |
1973年 | 206篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
1.
2.
Shanshan Zhuang Wenxiong Zheng Yunong Na Naiyi Chen Fan Gong Bingxuan Huang Stephen Brennan Charles Congyi Liu Jian Cheng Lukai Ma Huifan Liu 《International Journal of Food Science & Technology》2022,57(2):1093-1103
The β-Carotene (BC), an important precursor of vitamin A (VA), possesses antioxidant activity but is fat-soluble and has low bioavailability. In previous in-vitro assays evaluating antioxidant and 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) free radical scavenging, both BC and VA showed a strong ability to scavenge radicals and protected cells from oxidative stress. Here, we used artificially simulated gastrointestinal digestion and Caco-2 cell absorption models to evaluate the bioavailability of the BC during gastrointestinal digestion and absorption using high-performance liquid chromatography (HPLC) analysis. We observed high absorptive and transfer rates of BC and detected retinol metabolites (Vitamin A). Therefore, BC can be detected in the acidic gastrointestinal environment using HPLC. Optimised method provided better separation of BC and VA in the column, improving the accuracy of the test results. 相似文献
3.
Jean-Claude Malela-Majika Sandile Charles Shongwe Olatunde Adebayo Adeoti 《Quality and Reliability Engineering International》2021,37(8):3314-3322
The sensitivity of a monitoring scheme depends on many factors including the variance of the charting statistic which is very important in the computation of the control limits. This paper discusses the computation of the variance of the recently proposed hybrid homogeneously weighted moving average (HHWMA) scheme which was based on an incorrect assumption. The correct variance is used to evaluate the run-length characteristics of the HHWMA scheme. It is observed that the incorrect variance has a significant impact on the sensitivity (or performance) of the HHWMA scheme. 相似文献
4.
Belcher Calvin H. Zheng Baolong MacDonald Benjamin E. Langlois Eric D. Lehman Benjamin Pearce Charles Delaney Robert Apelian Diran Lavernia Enrique J. Monson Todd C. 《Journal of Materials Science》2022,57(9):5518-5532
Journal of Materials Science - For transformers and inductors to meet the world’s growing demand for electrical power, more efficient soft magnetic materials with high saturation magnetic... 相似文献
5.
Number entry is a ubiquitous activity and is often performed in safety- and mission-critical procedures, such as healthcare, science, finance, aviation and in many other areas. We show that Monte Carlo methods can quickly and easily compare the reliability of different number entry systems. A surprising finding is that many common, widely used systems are defective, and induce unnecessary human error. We show that Monte Carlo methods enable designers to explore the implications of normal and unexpected operator behaviour, and to design systems to be more resilient to use error. We demonstrate novel designs with improved resilience, implying that the common problems identified and the errors they induce are avoidable. 相似文献
6.
7.
Sarah Gilgunn Keefe Murphy Henning Stckmann Paul J. Conroy T. Brendan Murphy R. William Watson Richard J. OKennedy Pauline M. Rudd Radka Saldova 《International journal of molecular sciences》2020,21(23)
The diagnosis and treatment of prostate cancer (PCa) is a major health-care concern worldwide. This cancer can manifest itself in many distinct forms and the transition from clinically indolent PCa to the more invasive aggressive form remains poorly understood. It is now universally accepted that glycan expression patterns change with the cellular modifications that accompany the onset of tumorigenesis. The aim of this study was to investigate if differential glycosylation patterns could distinguish between indolent, significant, and aggressive PCa. Whole serum N-glycan profiling was carried out on 117 prostate cancer patients’ serum using our automated, high-throughput analysis platform for glycan-profiling which utilizes ultra-performance liquid chromatography (UPLC) to obtain high resolution separation of N-linked glycans released from the serum glycoproteins. We observed increases in hybrid, oligomannose, and biantennary digalactosylated monosialylated glycans (M5A1G1S1, M8, and A2G2S1), bisecting glycans (A2B, A2(6)BG1) and monoantennary glycans (A1), and decreases in triantennary trigalactosylated trisialylated glycans with and without core fucose (A3G3S3 and FA3G3S3) with PCa progression from indolent through significant and aggressive disease. These changes give us an insight into the disease pathogenesis and identify potential biomarkers for monitoring the PCa progression, however these need further confirmation studies. 相似文献
8.
9.
Choi Paul Santos Christian Ariane Kim Min-Kun Jung Hyunsook Hong Do-Young Koo Junemo 《Journal of Mechanical Science and Technology》2021,35(11):5007-5022
Journal of Mechanical Science and Technology - This study delivers equations useful for low-height pleated fibrous filter design: two pressure drop equations and one set of optimum design equations... 相似文献
10.
Dr. Raysa Khan Tareque Dr. Storm Hassell-Hart Dr. Tobias Krojer Dr. Anthony Bradley Dr. Srikannathasan Velupillai Dr. Romain Talon Dr. Michael Fairhead Dr. Iain J. Day Kamlesh Bala Dr. Robert Felix Dr. Paul D. Kemmitt Prof. Paul Brennan Prof. Frank von Delft Dr. Laura Díaz Sáez Prof. Kilian Huber Prof. John Spencer 《ChemMedChem》2020,15(24):2513-2520
Combined photochemical arylation, “nuisance effect” (SNAr) reaction sequences have been employed in the design of small arrays for immediate deployment in medium-throughput X-ray protein–ligand structure determination. Reactions were deliberately allowed to run “out of control” in terms of selectivity; for example the ortho-arylation of 2-phenylpyridine gave five products resulting from mono- and bisarylations combined with SNAr processes. As a result, a number of crystallographic hits against NUDT7, a key peroxisomal CoA ester hydrolase, have been identified. 相似文献