全文获取类型
收费全文 | 2763篇 |
免费 | 92篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 16篇 |
综合类 | 3篇 |
化学工业 | 389篇 |
金属工艺 | 48篇 |
机械仪表 | 27篇 |
建筑科学 | 53篇 |
矿业工程 | 5篇 |
能源动力 | 68篇 |
轻工业 | 185篇 |
水利工程 | 7篇 |
石油天然气 | 8篇 |
无线电 | 320篇 |
一般工业技术 | 336篇 |
冶金工业 | 1062篇 |
原子能技术 | 13篇 |
自动化技术 | 319篇 |
出版年
2024年 | 5篇 |
2023年 | 36篇 |
2022年 | 54篇 |
2021年 | 99篇 |
2020年 | 72篇 |
2019年 | 86篇 |
2018年 | 76篇 |
2017年 | 75篇 |
2016年 | 111篇 |
2015年 | 57篇 |
2014年 | 105篇 |
2013年 | 113篇 |
2012年 | 103篇 |
2011年 | 116篇 |
2010年 | 99篇 |
2009年 | 72篇 |
2008年 | 78篇 |
2007年 | 52篇 |
2006年 | 40篇 |
2005年 | 46篇 |
2004年 | 28篇 |
2003年 | 29篇 |
2002年 | 33篇 |
2001年 | 27篇 |
2000年 | 29篇 |
1999年 | 53篇 |
1998年 | 335篇 |
1997年 | 189篇 |
1996年 | 101篇 |
1995年 | 70篇 |
1994年 | 53篇 |
1993年 | 60篇 |
1992年 | 22篇 |
1991年 | 26篇 |
1990年 | 21篇 |
1989年 | 14篇 |
1988年 | 14篇 |
1987年 | 15篇 |
1986年 | 16篇 |
1985年 | 12篇 |
1984年 | 5篇 |
1983年 | 11篇 |
1982年 | 16篇 |
1981年 | 13篇 |
1980年 | 12篇 |
1979年 | 10篇 |
1978年 | 7篇 |
1977年 | 38篇 |
1976年 | 92篇 |
1955年 | 2篇 |
排序方式: 共有2859条查询结果,搜索用时 15 毫秒
71.
Colon atresia is a rare cause of intestinal obstruction in the neonate and requires early diagnosis and prompt surgical treatment. It is impossible in the neonate to differentiate colon atresia from other forms of obstruction at the time of initial presentation. The diagnosis is confirmed roentgenographically, including views of the abdomen and contrast barium enema series. Lesions proximal to the splenic flexure are treated with initial resection of the atretic segment and a primary anastomosis. Those lesions distal to the splentic flexure are managed initally with a diverting loop colostomy with subsequent staged resection and anastomosis. 相似文献
72.
R. Newsome N. Tran G.M. Paoli L.A. Jaykus B. Tompkin M. Miliotis T. Ruthman E. Hartnett F.F. Busta B. Petersen F. Shank J. McEntire J. Hotchkiss M. Wagner D.W. Schaffner 《Journal of food science》2009,74(2):R39-R45
ABSTRACT: Through a cooperative agreement with the U.S. Food and Drug Administration, the Institute of Food Technologists developed a risk-ranking framework prototype to enable comparison of microbiological and chemical hazards in foods and to assist policy makers, risk managers, risk analysts, and others in determining the relative public health impact of specific hazard–food combinations. The prototype is a bottom-up system based on assumptions that incorporate expert opinion/insight with a number of exposure and hazard-related risk criteria variables, which are propagated forward with food intake data to produce risk-ranking determinations. The prototype produces a semi-quantitative comparative assessment of food safety hazards and the impacts of hazard control measures. For a specific hazard–food combination the prototype can produce a single metric: a final risk value expressed as annual pseudo-disability adjusted life years (pDALY). The pDALY is a harmonization of the very different dose–response relationships observed for chemicals and microbes. The prototype was developed on 2 platforms, a web-based user interface and an Analytica® model (Lumina Decision Systems, Los Gatos, Calif., U.S.A.). Comprising visual basic language, the web-based platform facilitates data input and allows use concurrently from multiple locations. The Analytica model facilitates visualization of the logic flow, interrelationship of input and output variables, and calculations/algorithms comprising the prototype. A variety of sortable risk-ranking reports and summary information can be generated for hazard–food pairs, showing hazard and dose–response assumptions and data, per capita consumption by population group, and annual p-DALY. 相似文献
73.
Jhon Larry Moreno Thierry Tran Borja Cantero-Tubilla Karina López-López Luis Augusto Becerra Lopez Lavalle Dominique Dufour 《International Journal of Food Science & Technology》2021,56(3):1171-1183
The physicochemical and physiological attributes of three contrasting commercial varieties of Musaceae, Dominico Harton (plantain), Guineo (cooking banana) and Gros Michel (dessert banana), were evaluated and statistically analysed during post-harvest ripening. Quality attributes differed markedly among varieties, both in fresh fruits and during ripening. Variety (V) had a significant effect (P < 0.001) on all attributes except total soluble solids (TSS), carotenes and total chlorophyll. Storage time (ST) had a significant effect on all attributes except colour parameter b* and total carotenes. Starch levels decreased significantly (P < 0.001) during ripening, with nearly complete hydrolysis in Gros Michel, followed by Guineo and Dominico Harton. Discriminant analysis showed that central diameter, TSS of the pulp, colour parameter a* and total starch had the highest weight in the differentiation among varieties. These results point out which parameters may help improve current methods for monitoring ripening of bananas, in particular the commercially important varieties in this study. 相似文献
74.
Maria A. Ospina Monica Pizarro Thierry Tran Julien Ricci John Belalcazar Jorge L. Luna Luis F. Londoño Sandra Salazar Hernan Ceballos Dominique Dufour Luis A. Becerra Lopez-Lavalle 《International Journal of Food Science & Technology》2021,56(3):1343-1353
The objective of this study was to characterise the nutritional potential of leaves and identify a diversity centre with low cyanide and high nutrient content among 178 Latin American cassava genotypes. This field-based collection represents the seven diversity centres, held at The International Center for Tropical Agriculture (CIAT Palmira, Colombia) by the Cassava Program. The cyanide, all-trans-β-carotene and lutein concentrations in cassava leaves ranged from 346 to 7484 ppm dry basis (db), from 174–547 μg g−1 db and 15–181 μg g−1 db, respectively. Cassava leaves also showed significant levels of essential amino acids leucine, lysine, phenylalanine, valine and threonine, and average total protein content of 26.24 g 100 g−1 db. Among seven diversity centres, South American rainforest group showed low cyanide and high carotene content in leaves. In addition, VEN77 and PAN51 genotypes stood out for having low cyanide in leaves and roots and high carotene in leaves. This genetic diversity can be used to select high potential progenitors for breeding purposes. 相似文献
75.
Yanqiao Zhao Khanh Tran Margaret Brennan Charles Brennan 《International Journal of Food Science & Technology》2021,56(6):2687-2695
Polyphenols were extracted from five kinds of New Zealand grape pomace (Sauvignon Blanc, Pinot Gris, Gerwurztraminer, Merlot and Pinot Noir) at 30, 50 and 70 °C in an ultrasonic generator. The extraction kinetics for total phenol, anthocyanin and tannin were determined. The results of dynamics study showed that the extraction of total polyphenols, anthocyanin and tannin followed first-order reaction kinetics during the extraction at 30, 50 and 70 °C. The total phenolic content, anthocyanin conten, and tannin content of water–ethanol extracts from grape pomaces were compared, and the parameters in the extraction kinetics equations were determined. The extraction results showed that the Pinot Noir pomace extract had the highest total phenolic content of 59.95 mg GAE g−1 pomace and tannin content of 79.93 mg EE g−1 pomace. The anthocyanin content in Merlot pomace extract was the highest, which was 4.50 CE g−1 pomace. The results might be of great significance for the development of grape pomace or its polyphenol and/or anthocyanin components as an antioxidant source with natural and inexpensive benefits. 相似文献
76.
Kha Tuyen Chan Nguyen Cong Thanh Tran Luyen Thi Truong Trung Tan 《Food science and biotechnology》2021,30(12):1519-1526
Food Science and Biotechnology - The plant Morinda citrifolia L. (Noni) has been the subject of several recent research due to its positive impact on the treatment and prevention of a variety of... 相似文献
77.
Quan Nguyen Minh Quoc Dat Lai Hoang Nguy Minh Minh Tu Tran Kieu Ngoc Lam Gia Uyen Le My Phung Hang Hoang Dung Nguyen Tran Diem Ai Chau Ngoc Thuc Trinh Doan 《International Journal of Food Science & Technology》2022,57(7):4507-4517
To prevent the adulteration of agricultural resources and provide a solution to enhance the green coffee bean supply chain, authentication using the near-infrared spectroscopy (NIRS) technique was investigated. Partial least square with discrimination analysis (PLS-DA) models combined with various preprocessing methods were built from NIR spectra of 153 Vietnamese green coffee samples. The model combined with the standard normal variate and the first order of derivative yielded excellent performance in predicting coffee species with the error cross-validation of 0.0261. PLS-DA model of mean centre and first-order derivative spectra also yielded good performance in verifying geographical indication of green coffee with the error of 0.0656. By contrast, the predicting abilities of post-harvest methods were poor. The overall results showed a high potential of the NIRS in online authentication practices. 相似文献
78.
80.
Wang X Zhao S Harbottle H Tran T Blickenstaff K Abbott J Meng J 《Journal of food protection》2011,74(4):616-621
Campylobacter isolates (n = 297; 202 C. jejuni and 95 C. coli isolates) recovered from 2,513 retail meat samples (chicken breasts, ground turkey, ground beef, and pork chops) were examined for antimicrobial susceptibility. The isolates were further analyzed for genetic relatedness by pulsed-field gel electrophoresis (PFGE) using SmaI and KpnI restriction enzymes, and a subset of isolates (n = 174) were subtyped by multilocus sequence typing (MLST). The resistance most frequently observed was that to doxycycline (27.6%), followed by ciprofloxacin (13.8%) and erythromycin (6.4%). All isolates were susceptible to gentamicin and meropenem. C. coli showed higher resistance to doxycycline than did C. jejuni (42.1 versus 20.8%) and lower resistance to ciprofloxacin than did C. jejuni (10.5 versus 15.3%). Erythromycin resistance was only observed in C. coli. PFGE using SmaI plus KpnI digestion generated 168 clusters from 297 isolates: 115 from C. jejuni and 53 from C. coli. MLST revealed 44 sequence types (STs) under 10 clonal complexes from 120 C. jejuni and 27 STs under two clonal complexes from 54 C. coli. There was a positive association between PFGE and STs; however, PFGE showed greater discriminatory power than MLST. Subtyping data did not correlate with antimicrobial resistance phenotypes. 相似文献