全文获取类型
收费全文 | 12962篇 |
免费 | 1294篇 |
国内免费 | 787篇 |
专业分类
电工技术 | 1049篇 |
综合类 | 1349篇 |
化学工业 | 1649篇 |
金属工艺 | 709篇 |
机械仪表 | 733篇 |
建筑科学 | 704篇 |
矿业工程 | 497篇 |
能源动力 | 388篇 |
轻工业 | 1298篇 |
水利工程 | 350篇 |
石油天然气 | 379篇 |
武器工业 | 239篇 |
无线电 | 1315篇 |
一般工业技术 | 1102篇 |
冶金工业 | 1662篇 |
原子能技术 | 298篇 |
自动化技术 | 1322篇 |
出版年
2024年 | 65篇 |
2023年 | 206篇 |
2022年 | 475篇 |
2021年 | 584篇 |
2020年 | 460篇 |
2019年 | 304篇 |
2018年 | 338篇 |
2017年 | 346篇 |
2016年 | 299篇 |
2015年 | 502篇 |
2014年 | 632篇 |
2013年 | 807篇 |
2012年 | 934篇 |
2011年 | 965篇 |
2010年 | 978篇 |
2009年 | 843篇 |
2008年 | 884篇 |
2007年 | 902篇 |
2006年 | 663篇 |
2005年 | 603篇 |
2004年 | 474篇 |
2003年 | 287篇 |
2002年 | 263篇 |
2001年 | 232篇 |
2000年 | 218篇 |
1999年 | 116篇 |
1998年 | 372篇 |
1997年 | 259篇 |
1996年 | 162篇 |
1995年 | 110篇 |
1994年 | 97篇 |
1993年 | 99篇 |
1992年 | 41篇 |
1991年 | 39篇 |
1990年 | 38篇 |
1989年 | 41篇 |
1988年 | 34篇 |
1987年 | 18篇 |
1986年 | 26篇 |
1985年 | 19篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1982年 | 19篇 |
1981年 | 16篇 |
1980年 | 25篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 60篇 |
1976年 | 110篇 |
1961年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
S Ziebe B Bech K Petersen AL Mikkelsen A Gabrielsen AN Andersen 《Canadian Metallurgical Quarterly》1998,13(1):178-181
A new oxidative pathway for the degradation of caffeine(1,3,7-Trimethylxanthine, I) by a mixed culture consisting of strains belonging to the genera Klebsiella and Rhodococcus is presented. The mixed culture does not initiate degradation by N-demethylation either complete or partial, but instead carries out oxidation at the C-8 position resulting in the formation of 1,3,7-trimethyluric acid (TMU, II) which further gets degraded to 3,6,8-trimethylallantoin (TMA, III). Both TMU and TMA are hitherto not shown to be formed in the microbial system. Further degradation of TMA (III) by caffeine grown cells yields dimethylurea (VII) as one of the metabolites. Oxygen uptake studies indicated that caffeine(I) grown cells oxidized TMU(II), TMA (III), glyoxalic acid (VI), dimethylurea(VII), and monomethylurea(V), but not monomethyl and dimethyluric acids. The mixed culture does not accept theophylline(1,3-dimethylxanthine), theobromine(3,7-dimethylxanthine), and paraxanthine(1,7-dimethylxanthine) as the carbon source. 相似文献
12.
G
V Vijaya T Gireesh Gajanan S Bhat 《Journal of the science of food and agriculture》2002,82(5):493-496
The effect of enzymatic hydrolysis of proteins in milk using neutrase on the growth of the probiotic strain Bifidobacterium bifidus was evaluated by estimation of microbial growth, acidity, viscosity and flavour production. A significant increase in the growth of B bifidus was observed in neutrase‐hydrolysed milk. The setting time of bifidus‐cultured milk was advanced by about 12 h at 5% degree of hydrolysis. Enzymatic hydrolysis of proteins prior to cultivation also significantly increased the viscosity of the product. An approximately 60% increase in viscosity of the product was observed in neutrase‐hydrolysed milk. Production of steam‐volatile monocarbonyls as an indication of development of flavour was also higher in neutrase‐hydrolysed milk. The concentration of steam‐volatile monocarbonyls was 2.47 µmol per 100 ml in neutrase‐hydrolysed milk but only 1.84 µmol per 100 ml in control milk at the setting point of the curd. © 2002 Society of Chemical Industry 相似文献
13.
SA Balakirev VI Tsygankin AV Ivanov VI Atroshchenko AN Ianovski? M Sarfundin 《Canadian Metallurgical Quarterly》1997,43(4):445-447
The report deals with the development of procedures, evaluation of laser application and prevention of complications involved in intensive chemoradiation therapy of neoplasms of hemopoietic and lymphoid tissue in childhood. The clinical data on 548 patients, aged 2 months-15 years, with leukemia and solid tumor were evaluated. Laser application for treatment of different complications of chemoradiation therapy of pediatric leukemia proved a valuable innovation. It had a pronounced antiinflammatory and analgetic effect, promoted tissue regeneration processes and cut down the duration of complication treatment drastically. 相似文献
14.
15.
16.
17.
N. Nishiyama C. Caneau S. Tsuda G. Guryanov M. Hu R. Bhat Chung-En Zah 《Photonics Technology Letters, IEEE》2005,17(8):1605-1607
Error-free transmission through 10-km single-mode fiber at 10 Gb/s under -13-dB optical reflections has been demonstrated for the first time using a directly modulated 1.3-/spl mu/m InP-based VCSEL without any optical isolator. The 13-GHz relaxation oscillation frequency and stable polarization suppresses relative intensity noise degradation under optical reflection. Only 1-dB error-free power penalty has been observed with optical reflection set with the worst polarization direction. 相似文献
18.
介绍了平板显示控制芯片TO944的特点、功能、原理,并给出了基于T0944芯片的新型平板显示接口卡的软硬件实现方案,该方案具有电路简单、高可靠性、高性价比、高显示质量等优点,可用于各种不同类型与不同尺寸的平板显示器的显示。 相似文献
19.
Crystals of mixed NdLa heptamolybdates (max. size0.75×0.75×0.75 mm3) grown by silica gel technique were characterized using EDAX, IR, optical and scanning electron micrscopies.X-ray as well as electrn diffraction. The composition of the crystals was determined as (Nd1/2 La1/2 )2 Mo7O24·35H2O.The crystals exhibit varied morpholgies including square and octagonal platelets, cuboids, multifaceted crystal in coalesced and aggregated forms and spherulites.The XRD results indicate crystallinity of the grown material. Electron diffraction results suggest thermal instability of the material. IR results show the presence of peaks due to water and metal-oxygen bonds 相似文献
20.