全文获取类型
收费全文 | 10707篇 |
免费 | 664篇 |
国内免费 | 340篇 |
专业分类
电工技术 | 48篇 |
综合类 | 276篇 |
化学工业 | 753篇 |
金属工艺 | 126篇 |
机械仪表 | 162篇 |
建筑科学 | 24篇 |
矿业工程 | 4篇 |
能源动力 | 22篇 |
轻工业 | 5877篇 |
水利工程 | 5篇 |
石油天然气 | 50篇 |
武器工业 | 18篇 |
无线电 | 602篇 |
一般工业技术 | 3468篇 |
冶金工业 | 47篇 |
原子能技术 | 9篇 |
自动化技术 | 220篇 |
出版年
2024年 | 91篇 |
2023年 | 351篇 |
2022年 | 433篇 |
2021年 | 614篇 |
2020年 | 350篇 |
2019年 | 632篇 |
2018年 | 565篇 |
2017年 | 651篇 |
2016年 | 321篇 |
2015年 | 271篇 |
2014年 | 627篇 |
2013年 | 548篇 |
2012年 | 573篇 |
2011年 | 748篇 |
2010年 | 553篇 |
2009年 | 664篇 |
2008年 | 422篇 |
2007年 | 573篇 |
2006年 | 511篇 |
2005年 | 368篇 |
2004年 | 390篇 |
2003年 | 280篇 |
2002年 | 260篇 |
2001年 | 137篇 |
2000年 | 103篇 |
1999年 | 108篇 |
1998年 | 81篇 |
1997年 | 58篇 |
1996年 | 49篇 |
1995年 | 45篇 |
1994年 | 51篇 |
1993年 | 59篇 |
1992年 | 76篇 |
1991年 | 46篇 |
1990年 | 36篇 |
1989年 | 40篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 6篇 |
1962年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Modified Atmosphere Packaging Affects Ascorbic Acid, Enzyme Activity and Market Quality of Broccoli 总被引:1,自引:0,他引:1
Reduced ascorbic acid (RAA) content, total chlorophyll and green color retention, enzyme activities and texture changes were followed in broccoli spears packaged in polymeric film and nonpackaged during 96 hr storage (10°C). Concentrations within packages monitored by gas chromatography were (CO2,) 8% and (02) 10%. RAA retention, moisture content, total chlorophyll and color retention were greater in packaged broccoli. No differences were found between packaged and nonpackaged broccoli for ascorbate oxidase and peroxidase activities, or texture. 相似文献
52.
KEITH W. GATES AMANDA H. PARKER DIANA L. BAUER YAO-WEN HUANG 《Journal of food science》1993,58(2):314-317
We investigated pasteurization and storage of blue crabmeat in steel cans, aluminum cans, plastic cans, nonbarrier pouches, and barrier pouches. Fresh meat was packed in copolymer polyethylene/polypro-pylene cups, Saran® over-wrapped or vacuum skin packaged polystyrene trays, and nonbarrier pouches. Meat pasteurized in plastic and aluminum cans had better sensory and microbiological quality and longer shelf life than meat packed in steel cans. Oxygen-barrier pouches had the lowest quality and shortest shelf life. Nonbarrier pouches had product with quality similar to meat in steel cans, but with an extended shelf life. No packaging materials improved the microbiological shelf life of freshly cooked meat. Vacuum skin packaging resulted in improved sensory qualities of freshly cooked and picked meat. 相似文献
53.
A unique substrate MCPM (Mitsubishi Copper Polyimide Metal-base) technology has been developed by applying our basic copper/polyimide
technology.1 This new substrate technology MCPM is suited for a high-density, multi-layer, multi-chip, high-power module/package, such
as used for a computer. The new MCPM was processed using a copper metal base (110 × 110 mm), full copper system (all layers)
with 50-μm fine lines. As for pad metallizations for the IC assembly, we evaluated both Ni/Au for chip and wire ICs and solder
for TAB ICs. The total number of assembled ICs is 25. To improve the thermal dispersion, copper thermal vias are simultaneously
formed by electro-plating. This thermal via is located between the IC chip and copper metal base, and promotes heat dispersion.
We employed one large thermal via (4.5 mm?) and four small vias (1.0 mm?) for each IC pad. The effect of thermal vias and/or base metal is simulated by a computer analysis and compared with an alumina
base substrate. The results show that the thermal vias are effective at lowering the temperature difference between the IC
and base substrate, and also lowering the temperature rise of the IC chip. We also evaluated the substrate’s reliability by
adhesion test, pressure cooker test, etc. 相似文献
54.
Natalie Turner Pevindu Abeysinghe Pawel Sadowski Murray D. Mitchell 《International journal of molecular sciences》2021,22(4)
The reproductive status of dairy cows remains a challenge for dairy farmers worldwide, with impaired fertility linked to a significant reduction in herd profitability, due in part to impaired immunity, increased metabolic pressure, and longer postpartum anestrous interval (PPAI). Exosomes are nanovesicles released from a variety of cell types and end up in circulation, and carry proteins, bioactive peptides, lipids, and nucleic acids specific to the place of origin. As such, their role in health and disease has been investigated in humans and animals. This review discusses research into exosomes in the context of reproduction in dairy herds and introduces recent advances in mass-spectrometry (MS) based proteomics that have a potential to advance quantitative profiling of exosomal protein cargo in a search for early biomarkers of cattle fertility. 相似文献
55.
Brandi Miller Rabina Mainali Ravinder Nagpal Hariom Yadav 《International journal of molecular sciences》2021,22(4)
The prevalence of type 2 diabetes mellitus (T2D) is increasing worldwide, and there are no long-term preventive strategies to stop this growth. Emerging research shows that perturbations in the gut microbiome significantly contribute to the development of T2D, while microbiome modulators may be beneficial for T2D prevention. However, microbiome modulators that are effective, safe, affordable, and able to be administered daily are not yet available. Based on our previous pro- and prebiotic studies, we developed a novel synbiotic yogurt comprised of human-origin probiotics and plant-based prebiotics and investigated its impact on diet- and streptozotocin-induced T2D in mice. We compared the effects of our synbiotic yogurt to those of a commercially available yogurt (control yogurt). Interestingly, we found that the feeding of the synbiotic yogurt significantly reduced the development of hyperglycemia (diabetes) in response to high-fat diet feeding and streptozotocin compared to milk-fed controls. Surprisingly, the control yogurt exacerbated diabetes progression. Synbiotic yogurt beneficially modulated the gut microbiota composition compared to milk, while the control yogurt negatively modulated it by significantly increasing the abundance of detrimental bacteria such as Proteobacteria and Enterobacteriaceae. In addition, the synbiotic yogurt protected pancreatic islet morphology compared to the milk control, while the control yogurt demonstrated worse effects on islets. These results suggest that our newly developed synbiotic yogurt protects against diabetes in mice and can be used as a therapeutic to prevent diabetes progression. 相似文献
56.
The shear strength and aging characteristics of 63Sn–37Pb solder bumps were characterized with variation in solder ball and
UBM pad sizes. The shear strength increased with shorter effective crack size,a
effs
which was determined with the solder ball and pad sizes. The shear strength of the solder bumps on Au/Ni/Cu and Ni/Cu did
not change significantly with reflow time. Substantial decrease in the shear strength occurred for the solder bumps formed
on Au/Ni/Cu with aging treatment, and the shear strength after aging was also related to the bump shape which was determined
with the solder ball and pad sizes. 相似文献
57.
介绍了混凝沉淀-水解酸化-SBR工艺处理乳品生产废水的设计、调试、运行情况以及主要工艺设备。运行结果表明,在进水的SS、CODCr、BOD5、NH3-N的质量浓度分别为300~1000、800~3000、350~1500、25~70mg/L时,其处理出水的SS、CODCr、BOD5、NH3-N的平均质量浓度分别为7、12.29、1.78、9.3mg/L,达到了污水综合排放标准(GB8978-1996)的一级标准。该工艺具有占地面积小,处理效率好,运行费用低等特点,能广泛应用于乳品生产废水的处理。 相似文献
58.
59.
塑料在包装领域有着广泛的应用,其中聚酯(PET)性能优良,应用领域不断扩大。介绍了塑料包装不断通现的新技术,以及塑料包装环保问题的几点思路。 相似文献
60.
Francis W. Maloba Michael L. Rooney Paul Wormell Minh Nguyen 《Journal of the American Oil Chemists' Society》1996,73(2):181-185
The oxidative stability of sunflower oil (SFO) was measured during storage at 23 and 37°C in the presence of a novel oxygen-scavenging
film that contained polyfuryloxirane (PFO). Commercially refined and deodorized SFO was stored in a lighted room in sealed
transparent packages containing either PFO film or an antioxidant, 0.02% butylated hydroxytoluene (BHT). Oxidative stability
was evaluated by determination of peroxide values and gas-chromatographic measurement of headspace hexanal. SFO stored in
the presence of the oxygen-scavenging film was more stable than oil stored without the film, or than film stored with 0.02%
BHT. The PFO film scavenges oxygen through energy-transfer sensitization of singlet oxygen. The film is doped with eosin and
the naturally-occurring dye, curcumin, which absorb over a wide range of visible wavelengths. Curcumin transfers its absorbed
energy to eosin, which sensitizes the production of singlet oxygen. The singlet oxygen is scavenged by PFO. The use of two
dyes increases the efficiency of the sensitization process, reducing the illumination time and intensity required for effective
oxygen scavenging. 相似文献