全文获取类型
收费全文 | 6034篇 |
免费 | 550篇 |
国内免费 | 102篇 |
专业分类
电工技术 | 22篇 |
综合类 | 307篇 |
化学工业 | 2225篇 |
金属工艺 | 38篇 |
机械仪表 | 24篇 |
建筑科学 | 120篇 |
矿业工程 | 30篇 |
能源动力 | 288篇 |
轻工业 | 3140篇 |
水利工程 | 11篇 |
石油天然气 | 132篇 |
武器工业 | 9篇 |
无线电 | 23篇 |
一般工业技术 | 193篇 |
冶金工业 | 91篇 |
原子能技术 | 17篇 |
自动化技术 | 16篇 |
出版年
2024年 | 31篇 |
2023年 | 79篇 |
2022年 | 168篇 |
2021年 | 158篇 |
2020年 | 215篇 |
2019年 | 177篇 |
2018年 | 187篇 |
2017年 | 207篇 |
2016年 | 218篇 |
2015年 | 248篇 |
2014年 | 318篇 |
2013年 | 407篇 |
2012年 | 468篇 |
2011年 | 484篇 |
2010年 | 342篇 |
2009年 | 299篇 |
2008年 | 261篇 |
2007年 | 383篇 |
2006年 | 295篇 |
2005年 | 267篇 |
2004年 | 206篇 |
2003年 | 198篇 |
2002年 | 160篇 |
2001年 | 125篇 |
2000年 | 129篇 |
1999年 | 119篇 |
1998年 | 86篇 |
1997年 | 66篇 |
1996年 | 66篇 |
1995年 | 50篇 |
1994年 | 49篇 |
1993年 | 33篇 |
1992年 | 42篇 |
1991年 | 27篇 |
1990年 | 26篇 |
1989年 | 21篇 |
1988年 | 10篇 |
1987年 | 13篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1973年 | 2篇 |
1951年 | 2篇 |
排序方式: 共有6686条查询结果,搜索用时 15 毫秒
1.
2.
Functional expression and synergistic cooperation of xylan‐degrading enzymes from Hypocrea orientalis and Aspergillus niger
下载免费PDF全文
![点击此处可从《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
3.
Rice straw is the most abundant agricultural residue on a global scale and is widely available as feedstock for cellulosic fuel production. However, it is highly recalcitrant to biochemical deconstruction and also generates inhibitors that affect enzymatic saccharification. Rice straw from eastern Arkansas was subjected to dilute acid pretreatment (160 °C, 48 min and 1.0% sulfuric acid) and solid-state fermentation with two lignocellulolytic fungi, Trametes hirsuta and Myrothecium roridum, and their saccharification efficacies were compared. T. hirsuta and M. roridum were tested separately; pretreatment of rice straw with either strain for seven days resulted in 19 and 70% enrichment of its holocellulose content, respectively. However, liquid chromatography analysis of the alkali extracts showed significant differences in cell wall degradation by T. hirsuta and M. roridum. T. hirsuta removed 15% more phenolic compounds and 38% more glucan than M. roridum, while M. roridum removed 77% more xylan than T. hirsuta. Fungal and dilute acid pretreated biomass was then hydrolyzed using Accellerase® 1500, a saccharification cocktail. Saccharification efficiency of M. roridum was 37% higher than that of dilute acid pretreatment of rice straw, requiring 8% lower enzyme loading and 50% shorter enzymatic hydrolysis duration. Alkali extraction of fungal pretreated biomass also yielded 10–15 g kg−1 of acid precipitable polymeric lignin (APPL), which is a valuable co-product for biorefineries. In comparison to dilute acid pretreatment, fungal pretreatment could be a cost-effective alternative for the degradation of recalcitrant biomass, such as rice straw. 相似文献
4.
Yong Liu Kangzhuang Chen Fengbo Dong Shuai Peng Yongjie Cui Chenyu Zhang Keqing Han Muhuo Yu Hui Zhang 《Ceramics International》2018,44(9):10199-10203
In this paper, polyborosilazane precursor was synthesied from HMDZ, HSiCl3, BCl3 and CH3NH2 using a multistep method. By controlling the storage conditions, parts of the polyborosilazane fibers were hydrolyzed. FT-IR, NMR, XRD, TEM and monofilament tensile strength test were employed to study the effects of hydrolysis of precursor on the structures and properties of polymer-derived SiBN ceramic fibers. FT-IR and NMR results indicate that Si-N group in PBSZ reacts with H2O to form Si-O-Si group. After pyrolysis reaction at 1400℃, Si-O-Si group will finally transformed into highly ordered cristobalite and β-quartz, resulting in formation of the wrinkled surface of the obtained SiBN ceramic fiber. The strip-like defects on fiber surface, according to monofilament tensile strength test, had a significant effect on mechanical property of the obtained SiBN ceramic fiber and caused no increase in fiber tensile strength of hydrolytic polyborosilazane fiber before and after pyrolytic process. 相似文献
5.
Serdar Akbayrak Yalçın Tonbul Saim Özkar 《International Journal of Hydrogen Energy》2021,46(27):14259-14269
Herein, we report the use of tungsten(VI) oxide (WO3) as support for Rh0 nanoparticles. The resulting Rh0/WO3 nanoparticles are highly active and stable catalysts in H2 generation from the hydrolysis of ammonia borane (AB). We present the results of our investigation on the particle size distribution, catalytic activity and stability of Rh0/WO3 catalysts with 0.5%, 1.0%, 2.0% wt. Rh loadings in the hydrolysis reaction. The results reveal that Rh0/WO3 (0.5% wt. Rh) is very promising catalyst providing a turnover frequency of 749 min?1 in releasing 3.0 equivalent H2 per mole of AB from the hydrolysis at 25.0 °C. The high catalytic activity of Rh0/WO3 catalyst is attributed to the reducible nature of support. The report covers the results of kinetics study as well as comparative investigation of activity, recyclability, and reusability of colloidal(0) nanoparticles and Rh0/WO3 (0.5 % wt. Rh) catalyst in the hydrolysis reaction. 相似文献
6.
诱导水解法制备微细高分散金红石型二氧化钛 总被引:2,自引:0,他引:2
采用加热TiCl4稀溶液的方式,制备晶种,将其导入一定浓度的TiCl4溶液中进行诱导水解。所得的偏钛酸经干燥、煅烧后得到分散性好,D50为1 mm以下,金红石含量为≥95%的高纯TiO2,可用于生产PTC热敏电阻等铁电陶瓷。 相似文献
7.
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
8.
本文对芝麻营养保健成分的提取进行了系统的研究。确定了芝麻营养原液的制取工艺。为充分发挥芝麻的营养保健作用开辟了新的途径。 相似文献
9.
The mechanical fracture strength and toughness of short-fibre composites, injection moulded from compounds of poly(ethylene terephthalate) (PET) containing 10 and 30% (by weight) (w/o) glass, have been investigated and the dependence upon matrix hydrolytic stability determined. Mouldings have been characterised by several physical techniques to evaluate molecular weight, degradation rates, crystallinity and morphology, whilst time-dependent gravimetric data were derived to quantify sorption kinetics and allow comparisons with theoretical reaction rates to be made. During melt processing, PET is hydrolysed extremely rapidly by traces of moisture (<0.02w/o). yet the inherent strength of moulded composites declines significantly only below an apparently critical molecular weight. However, on long-term humid ageing in hot water, impact behaviour especially is rendered more complex by simultaneous crystallisation, molecular reorder and losses of interfacial bond strength. 相似文献
10.
在第一部分综合讨论的基础上对甘三酯立体专一分析方法作了初步探讨。以液体油(菜油)及固体脂(猪脂)为基质,系统地研究了这一分析方法,取得了经验并补充了一些具体验证方法。分析液体油的结果与文献数据相一致,分析猪脂的结果欠佳,还存在一些问题需待进一步研究。 相似文献