全文获取类型
收费全文 | 1766篇 |
免费 | 101篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 17篇 |
综合类 | 1篇 |
化学工业 | 429篇 |
金属工艺 | 39篇 |
机械仪表 | 48篇 |
建筑科学 | 68篇 |
矿业工程 | 4篇 |
能源动力 | 75篇 |
轻工业 | 214篇 |
水利工程 | 15篇 |
石油天然气 | 6篇 |
武器工业 | 1篇 |
无线电 | 166篇 |
一般工业技术 | 324篇 |
冶金工业 | 75篇 |
原子能技术 | 12篇 |
自动化技术 | 376篇 |
出版年
2023年 | 24篇 |
2022年 | 54篇 |
2021年 | 78篇 |
2020年 | 61篇 |
2019年 | 67篇 |
2018年 | 63篇 |
2017年 | 59篇 |
2016年 | 55篇 |
2015年 | 62篇 |
2014年 | 74篇 |
2013年 | 148篇 |
2012年 | 115篇 |
2011年 | 157篇 |
2010年 | 103篇 |
2009年 | 88篇 |
2008年 | 117篇 |
2007年 | 77篇 |
2006年 | 68篇 |
2005年 | 49篇 |
2004年 | 48篇 |
2003年 | 51篇 |
2002年 | 36篇 |
2001年 | 22篇 |
2000年 | 11篇 |
1999年 | 8篇 |
1998年 | 17篇 |
1997年 | 15篇 |
1996年 | 23篇 |
1995年 | 15篇 |
1994年 | 15篇 |
1993年 | 14篇 |
1992年 | 4篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1985年 | 11篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1911年 | 2篇 |
排序方式: 共有1870条查询结果,搜索用时 46 毫秒
91.
Biagio Barone Luigi Napolitano Marco Abate Luigi Cirillo Pasquale Reccia Francesco Passaro Carmine Turco Simone Morra Francesco Mastrangelo Antonio Scarpato Ugo Amicuzi Vincenzo Morgera Lorenzo Romano Francesco Paolo Calace Savio Domenico Pandolfo Luigi De Luca Achille Aveta Enrico Sicignano Massimiliano Trivellato Gianluca Spena Carlo DAlterio Giovanni Maria Fusco Raffaele Vitale Davide Arcaniolo Felice Crocetto 《International journal of molecular sciences》2022,23(7)
Testosterone is the most important hormone in male health. Aging is characterized by testosterone deficiency due to decreasing testosterone levels associated with low testicular production, genetic factors, adiposity, and illness. Low testosterone levels in men are associated with sexual dysfunction (low sexual desire, erectile dysfunction), reduced skeletal muscle mass and strength, decreased bone mineral density, increased cardiovascular risk and alterations of the glycometabolic profile. Testosterone replacement therapy (TRT) shows several therapeutic effects while maintaining a good safety profile in hypogonadal men. TRT restores normal levels of serum testosterone in men, increasing libido and energy level and producing beneficial effects on bone density, strength and muscle as well as yielding cardioprotective effects. Nevertheless, TRT could be contraindicated in men with untreated prostate cancer, although poor findings are reported in the literature. In addition, different potential side effects, such as polycythemia, cardiac events and obstructive sleep apnea, should be monitored. The aim of our review is to provide an updated background regarding the pros and cons of TRT, evaluating its role and its clinical applicability in different domains. 相似文献
92.
Ibironke A Ajayi Rotimi A Oderinde Victor O Taiwo Emmanuel O Agbedana 《Journal of the science of food and agriculture》2004,84(13):1715-1721
The nutritional value of Telfairia occidentalis seed and seed oil available in local market was studied in rats. The average values of the proximate analysis on dry matter basis were 203 g kg?1 crude protein, 536.3 g kg?1 fat, 39 g kg?1 ash, 95 g kg?1 crude fibre and 43.7 g kg?1 carbohydrate, while the moisture content was 75 g kg?1. The mineral analyses showed that T occidentalis seeds contain potassium (3280 mg kg?1), sodium (1230 mg kg?1), magnesium (60.8 mg kg?1), calcium (60.8 mg kg?1) and iron (13.0 mg kg?1). The oil extracted from the seed sample showed physicochemical properties that suggest its suitability for edible and industrial uses. The oil contained high levels of unsaturated fatty acids, oleic and linoleic, which accounted for 63.22% of total fatty acids recovered, while palmitic acid (27.4% of the oil by weight) was the most prevalent saturated fatty acid in the oil. No trace of eleostearic acid was detected in the oil. The effect on physical appearance, weight gain, organ weight, tissue and plasma cholesterol and triacylglycerol levels was determined in rats fed a diet containing 5% T occidentalis oil. These were compared with those of rats fed a control diet (0% T occidentalis oil) over an 8 week study period. Weekly monitoring of the rats showed good physical appearance and steady weight increase. The test rats were not anaemic and no mortality was recorded. While there was a significantly higher (p < 0.05) level of cholesterol in the heart of test rats compared with the control, there was a significantly lower (p < 0.05) plasma cholesterol level, suggesting that T occidentalis seed oil can be used to lower plasma levels of cholesterol. Histological examination of the sections of the heart, liver, kidney and spleen of the test rats revealed varying degrees of pathology. These include artherosclerotic changes in the walls of vasa vasori and lymphatics in the heart and hyaline degeneration of myofibrils, fatty infiltration of hepatocytes, and glomerular and tubular degeneration in the kidneys. These lesions may have been due to the effect of fatty acids, especially erucic acid, in the seed oil, which at 1.24% (less that the 5% conventional allowable limit for edible oils) may be intolerable for rats and may be unsuitable for human consumption. The seed oil may be used for industrial purposes such as soap making, lubrication and cosmetics for which it is well suited. Copyright © 2004 Society of Chemical Industry 相似文献
93.
Annalisa Paternò Daniela Verginelli Pamela Bonini Marisa Misto Cinzia Quarchioni Enrico Dainese Stefania Peddis Cristiana Fusco Daniela Vinciguerra Ugo Marchesi 《Food Analytical Methods》2018,11(5):1281-1290
Common wheat is one of the most important staple food crops worldwide. However, unlike other important staple crops such as maize or soybean, genetically modified (GM) wheat is not yet present in the global food market. Nonetheless, in the recent past, the adventitious presence of GM glyphosate-tolerant volunteers was reported in open wheat fields in the USA. The European Union Reference Laboratory for GM Food and Feed (EURL-GMFF) was therefore called to develop a strategy to detect such unauthorised GM wheat in wheat samples by using both taxon-specific and screening tests. Two candidate common wheat taxon-specific real-time PCR methods were suggested, one targeting ssII-D gene coding for starch synthase and the other targeting waxy-D1 gene, coding for granule-bound starch synthase. In the present study, the two above-mentioned real-time PCR taxon-specific methods were in-house verified and compared, proposing droplet digital PCR (ddPCR) as a new tool for supporting the application of the European Network of GMO Laboratories (ENGL) established method performance criteria. Preliminary performance data of waxy-D1 and ssII-D methods in ddPCR format are shown too to give a contribution to the bridging process from the consolidated to the emerging quantitative PCR methodology. 相似文献
94.
Emmanuel S. Ajisegiri Peter A. Sopade Adebayo B. Abass 《Journal of Stored Products Research》1994,30(4):331-338
Kuka is an important vegetable in the Nigerian food chain. The moisture sorption characteristics of the vegetable studied at 34, 37 and 45°C between aw 0.10–0.96, revealed a BET type II behaviour. The Kuka exhibited hysteresis and an increase in EMC with increase in aw and decrease in temperature. Four sorption models (Oswin, Halsey, Kuhn, and GAB) were studied and the Oswin model was the most suitable. The constants in the Oswin model and GAB monolayer moisture contents were obtained and found to be temperature-dependent. Heats of sorption were greater for desorption than adsorption and in either mode, they reduced with an increase in moisture content. An exponential equation was obtained to relate heat of sorption with moisture content. 相似文献
95.
Matilda Zemanov Emmanuel Lecomte Pavol
ajgalík Ralf Riedel 《Journal of the European Ceramic Society》2002,22(16):2963-2968
The pyrolised polysilazanes poly(hydridomethyl)silazane NCP 200 and poly(urea)silazane CERASET derived Si–C–N amorphous powders were used for preparation of micro/nano Si3N4/SiC composites by hot pressing. Y2O3–Al2O3 and Y2O3–Yb2O3 were used, as sintering aids. The resulting ceramic composites of all compositions were dense and polycrystalline with fine microstructure of average grain size <1 μm of both Si3N4 and SiC phases. The fine SiC nano-inclusions were identified within the Si3N4 micrograins. Phase composition of both composites consist of , β modifications of Si3N4 and SiC. High weight loss was observed during the hot pressing cycle, 12 and 19 wt.% for NCP 200 and CERASET precursors, respectively. The fracture toughness of both nanocomposites (NCP 2000 and CERASET derived) was not different. Indentation method measured values are from 5 to 6 MPa m1/2, with respect to the sintering additive system. Fracture toughness is slightly sensitive to the SiC content of the nanocomposite. Hardness increases with the content of SiC in the nanocomposite. The highest hardness was achieved for pyrolysed CERASET precursor with 2 wt.% Y2O3 and 6 wt.% Yb2O3, HV 23 GPa. This is a consequence of the highest SiC content as well as the chemical composition of additives. 相似文献
96.
Development and Characterization of Continuous SiC Fiber‐Reinforced HfB2‐Based UHTC Matrix Composites Using Polymer Impregnation and Slurry Infiltration Techniques
下载免费PDF全文
![点击此处可从《International Journal of Applied Ceramic Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Clifford J. Leslie Emmanuel E. Boakye Kristin A. Keller Michael K. Cinibulk 《International Journal of Applied Ceramic Technology》2015,12(1):235-244
This paper discusses the development of continuous SiC fiber‐reinforced HfB2‐SiC composite laminates. A range of techniques, based on resin‐based precursors and slurries, for infiltrating porous SiC preforms with HfB2 powder were developed. While resin‐based precursors proved to be ineffective due to low HfB2 yield and poor adhesion, the slurry infiltration techniques were effective to varying degrees. The greatest pore filling and composite densities were achieved using pressure and vibration‐assisted pressure infiltration techniques. SiCf/HfB2‐SiC laminates were subsequently developed via lamination, cure and pyrolysis of fabrics using a HfB2‐loaded polymeric SiC precursor, followed by HfB2 slurry infiltration and preceramic polymer infiltration and pyrolysis (PIP). Repeated PIP processing, for 6–10 cycles, resulted in density increases, from the 3.03–3.22 g/cm3 range after HfB2 slurry infiltration, to 3.97–4.03 g/cm3 after PIP processing. Correspondingly, there was a decrease in open porosity from approximately 52% to less than 11%. The matrix consisted of discreet, lightly sintered HfB2 particles dispersed in SiC. The PIP SiC matrix was primarily nanocrystalline after 1300°C pyrolysis, but experienced grain growth with further heat treatment at 1600°C. 相似文献
97.
Alexander Apelblat Taisa Zaharoskin Jaime Wisniak Emmanuel Korngold 《Journal of the American Oil Chemists' Society》1996,73(2):239-244
Formamide,N-methylformamide,N-dimethylformamide, dimethylsulfoxide, 1,2-butanediol, and 2-butane-1,4-diol were considered as potential extractants of fatty
acids from soybean and jojoba oils. Ternary liquid-liquid phase diagrams at 298.15 K, distribution, and selectivity coefficients
of oleic acid are reported. Of the investigated solvents, onlyN-methylformamide and 1,2-butanediol have desirable extraction characteristics. 相似文献
98.
99.
Cellular behavior is influenced by micro-concentration gradients existing in their immediate spatio-environment. A practical real-time measurement system, composed of miniaturized long-lasting sensors placed within a two-dimensional bioreactor and a 32-channel data acquisition system for ammonia, is presented in this paper aiming to generate the spatio-temporal ammonia concentration profiles for the whole culture process. Our results demonstrate the feasibility of the system and its applicability in elucidating the cell growth micro-environment within a bioreactor, which can potentially facilitate the intelligent control of ammonia levels in cell culture systems. The presented system is flexible enough to interface other sensors for generating their spatio-temporal profiles of the sensed cell culture parameters. 相似文献
100.