全文获取类型
收费全文 | 1054篇 |
免费 | 75篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 2篇 |
综合类 | 1篇 |
化学工业 | 452篇 |
金属工艺 | 21篇 |
机械仪表 | 24篇 |
建筑科学 | 42篇 |
矿业工程 | 4篇 |
能源动力 | 28篇 |
轻工业 | 268篇 |
水利工程 | 8篇 |
石油天然气 | 2篇 |
无线电 | 34篇 |
一般工业技术 | 131篇 |
冶金工业 | 24篇 |
原子能技术 | 2篇 |
自动化技术 | 89篇 |
出版年
2024年 | 2篇 |
2023年 | 18篇 |
2022年 | 86篇 |
2021年 | 78篇 |
2020年 | 39篇 |
2019年 | 40篇 |
2018年 | 44篇 |
2017年 | 47篇 |
2016年 | 47篇 |
2015年 | 50篇 |
2014年 | 46篇 |
2013年 | 74篇 |
2012年 | 79篇 |
2011年 | 94篇 |
2010年 | 65篇 |
2009年 | 59篇 |
2008年 | 55篇 |
2007年 | 34篇 |
2006年 | 35篇 |
2005年 | 18篇 |
2004年 | 20篇 |
2003年 | 19篇 |
2002年 | 16篇 |
2001年 | 14篇 |
2000年 | 6篇 |
1999年 | 9篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 10篇 |
1994年 | 3篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有1132条查询结果,搜索用时 11 毫秒
21.
22.
23.
Sorin Iorga Mihai Cojocaru Adriana Chivu Sorin Ciuca Mihail Burdusel Petre Badica Cédric Leuvrey Guy Schmerber Corinne Ulhaq-Bouillet Silviu Colis 《Metallurgical and Materials Transactions A》2014,45(7):3088-3096
We report on the changes on the microstructural, hardness, and corrosion properties induced by carbo-chromization of 316L stainless steel prepared by Spark Plasma Sintering technique. The thermo-chemical treatments have been performed using pack cementation. The carburizing and chromization were carried out between 1153 K (880 °C)/4 h to 1253 K (980 °C)/12 h and 1223 K (950 °C)/6 h to 1273 K (1000 °C)/12 h in a solid powder mixture of charcoal/BaCO3 and ferrochromium/alumina/NH4Cl, respectively. The obtained layers were investigated using X-ray and electron diffraction, optical and scanning electron microscopies, Vickers micro-hardness, and potentiodynamic measurements. The thickness of the carbo-chromized layer ranges between 300 and 500 μm. Besides the host γ-phase, the layers are mainly constituted of carbides (Fe7C3, Cr23C6, Cr7C3, and Fe3C) and traces of α′-martensite. The average hardness values decrease smoothly from 650 HV at the sample surface down to 200 HV at the center of the sample. The potentiodynamic tests revealed that the carbo-chromized samples have smaller corrosion resistance with respect to the untreated material. For strong chromization regimes, the corrosion rate is increased by a factor of four with respect to that of the untreated material, while the micro-hardness of the layer is three times larger. Such materials are suited to be used in environments where good corrosion resistance and wear properties are required. 相似文献
24.
Adriana Gadioli Tarone Luiz Henrique Fasolin Fabiana de Assis Perrechil Míriam Dupas Hubinger Rosiane Lopes da Cunha 《Food and Bioproducts Processing》2013,91(2):111-120
Soy protein fractions rich in β-conglycinin (7S) or glycinin (11S) were freeze dried or spray dried at temperatures of 120, 150 or 180 °C. The fractions were characterized for their particle size distribution, sorption isotherms and by scanning differential calorimetry. The gelling capacity of the protein fractions was studied at pH values of 3 and 7 using oscillatory measurements, mechanical properties and water holding capacity. The rheological measurements showed that viscous modulus (G″) predominated at low temperatures and the elastic modulus (G′) at high temperatures. At pH 3, the G′–G″ crossover occurred at lower temperatures when compared to pH 7. This behaviour was more accentuated for the 11S fractions due to its capacity to form stronger gels. An increase of drying temperature led to a displacement of the gel point to higher temperatures and decreased the elasticity modulus or gelling capacity of protein fractions. These results were confirmed by the mechanical properties, since at higher temperatures the gels were more fragile and brittle, especially when formed at pH 7. 相似文献
25.
26.
Gámbaro A Raggio L Dauber C Claudia Ellis A Toribio Z 《Archivos latinoamericanos de nutrición》2011,61(3):308-315
The relationship between nutritional knowledge and the consumption frequency of preferred food-types was studied among one sample of Uruguayan consumers. A locally-adapted version of Parmenter & Wardle's General Nutrition Knowledge Questionnaire and a food consumption survey based on 39 food groups were completed by a total of 270 participants. Cluster Analysis enabled the identification of two clusters showing different levels of nutritional knowledge--cluster 1 (n = 177) and cluster 2 (n = 93), providing an average of 73.6% and 52.9% of correct answers, respectively. These clusters differed significantly (p < or = 0.05) in age and educational distribution--cluster 1 was composed mainly by older adults and persons with a higher educational level. A number of areas were identified where nutritional knowledge was extremely poor, as was the case with the recommended daily fruit and vegetable intake and the caloric content of the nutrients. Overall, nutritional knowledge was found to have a positive influence on food preferences and consumption frequency, those participants with a higher nutritional knowledge reporting a higher consumption of fruits, vegetables and low-fat products, in addition to a lower consumption of high-fat and high-sugar foods. 相似文献
27.
Cytotoxic Activity and Structure–Activity Relationship of Triazole‐Containing Bis(Aryl Ether) Macrocycles 下载免费PDF全文
Dr. Eduardo Hernández‐Vázquez Dr. Alejandra Chávez‐Riveros Dr. Adriana Romo‐Pérez María Teresa Ramírez‐Apán Dr. Alma D. Chávez‐Blanco Dr. Rocío Morales‐Bárcenas Dr. Alfonso Dueñas‐González Dr. Luis D. Miranda 《ChemMedChem》2018,13(12):1193-1209
Cancer continues to be a worldwide health problem. Certain macrocyclic molecules have become attractive therapeutic alternatives for this disease because of their efficacy and, frequently, their novel mechanisms of action. Herein, we report the synthesis of a series of 20‐, 21‐, and 22‐membered macrocycles containing triazole and bis(aryl ether) moieties. The compounds were prepared by a multicomponent approach from readily available commercial substrates. Notably, some of the compounds displayed interesting cytotoxicity against cancer (PC‐3) and breast (MCF‐7) cell lines, especially those bearing an aliphatic or a trifluoromethyl substituent on the N‐phenyl moiety (IC50<13 μm ). Additionally, some of the compounds were able to induce apoptosis relative to the solvent control; in particular, (Z)‐N‐cyclohexyl‐7‐oxo‐6‐[4‐(trifluoromethyl)phenyl]‐11H‐3,10‐dioxa‐6‐aza‐1(4,1)‐triazola‐4(1,3),9(1,4)‐dibenzenacyclotridecaphane‐5‐carboxamide ( 12 f ) was the most potent in this regard (22.7 % of apoptosis). 相似文献
28.
29.
Panagiotis Sarantis Alexandros Bokas Adriana Papadimitropoulou Evangelos Koustas Stamatios Theocharis Pavlos Papakotoulas Dimitrios Schizas Alexandros Papalampros Evangelos Felekouras Athanasios G. Papavassiliou Michalis V. Karamouzis 《International journal of molecular sciences》2021,22(13)
Pancreatic Cancer (PC) is recognized as a highly thrombogenic tumor; thus, low-molecular-weight heparin (LMWH) such as tinzaparin is routinely used for PC patients. On the basis of combinatorial therapy approaches to treat highly malignant and refractory cancers such as PC, we hypothesized that tinzaparin can augment the effectiveness of traditional chemotherapeutic drugs and induce efficient antitumor activity. PANC-1 and MIAPaCa-2 were incubated alone or in combination with tinzaparin, nab-paclitaxel and gemcitabine. In vivo evaluation of these compounds was performed in a NOD/SCID mouse using a model injected with PANC-1. Tinzaparin enhances the anti-tumor effects of nab-paclitaxel and gemcitabine in mtKRAS PC cell lines via apoptosis in in vitro experiments. The triple combination power acts through the induction of apoptosis, reduction of the proliferative potential and angiogenesis; hence, contributing to a decrease in tumor volume observed in vivo. The triple regimen provided an extra 24.3% tumor reduction compared to the double combination (gemcitabine plus nab-paclitaxel). Combinatorial strategies can create novel therapeutic approaches for the treatment of patients with PC, achieving a better clinical outcome and prolonged survival. Further prospective randomized research is needed and the investigation of various concentrations of tinzaparin above 150 UI/Kg, would potentially provide a valuable synergistic effect to the conventional therapeutic compounds. 相似文献
30.
Pâmela Maria Moreira Fonseca Luciano dos Santos Feitosa Adriana Barrinha Fernandes Ranato Amaro Zângaro Walter Miyakawa Carlos José de Lima 《臭氧:科学与工程》2015,37(1):85-89
Ozone gas diluted in water has been shown to produce significant results in terms of the elimination of microorganisms. Streptococcus mutans is the etiologic agent of dental caries. Methods using water containing ozone and an ultrasonic cleaner were employed for the disinfection of a curette. Streptococcus mutans was grown in a selective medium. The curette was submitted to disinfection by water containing ozone, by ultrasound, and then both techniques were combined. The results show that either method produced a significant microbial reduction, but the efficacy of both methods combined was greater. This method of disinfection proved to be both viable and cheap. 相似文献