首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2913篇
  免费   78篇
  国内免费   99篇
电工技术   62篇
综合类   113篇
化学工业   126篇
金属工艺   334篇
机械仪表   139篇
建筑科学   87篇
矿业工程   1篇
能源动力   30篇
轻工业   729篇
水利工程   26篇
石油天然气   2篇
武器工业   1篇
无线电   99篇
一般工业技术   337篇
冶金工业   721篇
原子能技术   42篇
自动化技术   241篇
  2023年   9篇
  2022年   19篇
  2021年   23篇
  2020年   17篇
  2019年   26篇
  2018年   18篇
  2017年   17篇
  2016年   19篇
  2015年   22篇
  2014年   73篇
  2013年   366篇
  2012年   140篇
  2011年   189篇
  2010年   118篇
  2009年   150篇
  2008年   84篇
  2007年   77篇
  2006年   98篇
  2005年   47篇
  2004年   71篇
  2003年   41篇
  2002年   26篇
  2001年   19篇
  2000年   20篇
  1999年   32篇
  1998年   232篇
  1997年   233篇
  1996年   109篇
  1995年   62篇
  1994年   55篇
  1993年   65篇
  1992年   31篇
  1991年   42篇
  1990年   41篇
  1989年   42篇
  1988年   35篇
  1987年   39篇
  1986年   31篇
  1985年   23篇
  1984年   15篇
  1983年   26篇
  1982年   19篇
  1981年   20篇
  1980年   21篇
  1979年   19篇
  1978年   23篇
  1977年   37篇
  1976年   59篇
  1975年   21篇
  1974年   10篇
排序方式: 共有3090条查询结果,搜索用时 46 毫秒
1.
After the remarkable increase of Internet users and broadband Internet subscribers at the end of the 20th century, the size of Korean Internet and e-commerce market steadily increased but the growth rate has been either stagnant or decreased. Trends of Korean Internet and e-commerce market are summarized in this paper the trends on Internet usage are introduced. Trends of online games, blogs and wireless Internet are introduced. The trends of Korean Internet market may have implications for China and Japan.  相似文献   
2.
A phase III clinical trial was designed to determine if more intensive induction and consolidation therapy for acute myeloblastic leukemia increases the remission rate and prolongs survival. A minor objective was to determine if the use of non-cross resistant drugs was more effective than the same drugs used for induction. Patients with untreated leukemia between the ages of 15 and 50 were given daunorubicin 45 mg/m2 for the first 3 days of a 10-day continuous infusion of cytosine arabinoside, initially at a dose of 2000 mg/m2 but reduced to 100 mg/m2 because of toxicity. Those under 36 achieving a complete remission and with an histocompatible donor were assigned to a transplant arm. The rest were randomized to receive one of three consolidation arms: A, cytosine arabinoside, 200 mg/m2 daily for 7 days and daunorubicin 45 mg/m2 daily for 3 days for three courses; B, one course as in Arm A followed by amsacrine, 120 mg/m2 daily for 5 days followed by a 5-day continuous infusion of azacytidine, 150 mg/m2/day; C, thioguanine and cytosine arabinoside, 100 mg/m2 every 12 h and daunorubicin 10 mg/m2 daily for 5 days for three courses followed by four maintenance courses of cytosine arabinoside, 100 mg/m2 daily for 5 days and daunorubicin, 45 mg/m2 for 2 days every 13 weeks. From 1981 to 1986, 398 eligible patients were enrolled and 219 achieved a complete remission. The initial induction dose of cytosine arabinoside was reduced after five of 29 patients exhibited fatal gastrointestinal toxicity. Only 11 patients were assigned to the transplant arm. There were no significant differences in the consolidation arms. The 5 year disease-free survivals were 38, 31 and 27% in arms A, B, and C respectively. Intensive consolidation therapy with the same or different drugs used in induction was as effective as lower dose consolidation followed by maintenance therapy.  相似文献   
3.
4.
5.
The sorghum distillery residue (SDR) has been an underutilized by‐product with estimated production of 150 ton/day in Kinmen, Taiwan. The objective of this study was to test for any physiological effects of SDR, thus to utilize it as a nutraceutical feed ingredient in diets for cultured fish. Hot air‐dried, wet, and dehulled‐wet sorghum distillery residue showed 63%, 90% and 97% inhibition of the hemoglobin‐catalyzed oxidation of linoleic acid compared to soybean (13%) and rice bran (78%). The feed formulated with 20% wet or dehulled‐wet sorghum distillery residue both showed an antioxidant activity of 68% being higher than the control diet (53%). Feeding these diets to cultured grey mullet for 60 days in summer (temperature ranged 24–30C), resulted in a lower hydroperoxide content in gill tissue, as shown by a chemiluminesence intensity of 1806 or 1409 mV as opposed to 2666 mV for fish fed a control diet. In winter, when the water temperature decreased to 14C, grey mullet fed a diet consisting of 10% dehulled wet sorghum distillery residue had a blood viscosity of 1.9 mPas and a hematocrit value of 33%, in contrast to 3.6 mPas and 41% for control. The blood of the control group started to aggregate in 6 h and showed hemolysis, while the mullet fed dehulled, wet sorghum distillery residue did not show blood aggregation, maintained normal fluidity and erythrocyte membrane integrity. It seems that cultured fish may have the potential as an animal model for prescreening antioxidant and blood thinning effects of food ingredients.  相似文献   
6.
7.
Effects of oil droplets in an agar gel matrix were investigated by mechanical analyses and sensory evaluation. The results for compressive and puncture properties were expressed in terms of relative values. All compressive properties; stress, strain and compressive energy of emulsion gels, as obtained by compression tests, decreased with both increases of oil droplet size and oil volume fraction. The stress, strain and energy of the emulsion gels obtained by puncture tests did not change with an increase in oil droplet size. Results of sensory evaluation showed that the sample containing small oil droplets was harder than that with large oil droplets. On the other hand, the large oil droplet sample was oilier than that with small oil droplets. The sensory evaluations for hardness and oiliness of emulsion gels did not exhibit significant relations to most of the properties of mechanical analyses.  相似文献   
8.
Complex multi‐phase Al–Sn–Si alloys are commonly employed in the manufacture of small automotive plain bearings. The fundamental fatigue initiation behaviour of this class of alloys is currently not well understood. A range of analytical techniques were applied to investigate preferential initiation site location and to attempt to identify critical microstructural features. It was apparent from experimental studies that points of fatigue crack initiation are associated with the Si secondary phase. Using tessellation approaches and subsequently both adaptive numerical modelling and micro‐scale finite element modelling allowed the identification of features affecting the probability that a given Si phase would initiate a fatigue crack.  相似文献   
9.
3H-labeled S. typhimurium cells inactivated by gamma-radiation (60Co) and by formaldehyde (5%) were used to determine if cell viability affected attachment to poultry skin. Both gamma-irradiated and formal-dehyde-treated cells attached like live cells. There was no difference in attachment between cells grown in a chemically defined medium (SCDM) or in brain heart infusion broth (BHI). Live and gamma-irradiated cells and BHI-grown and SCDM-grown cells had similar surface hydrophobicity. Live and gamma-irradiated cells had similar cell surface charges, whereas BHI and SCDM-grown cells had different surface charges. Differences in cell surface charge did not affect attachment rate.  相似文献   
10.
The N-acetyltransferase activity was determined in 58 common fruits and vegetables. The assay was based on acetylation of 2-aminofluorene or p-amino-benzoic acid, followed by high pressure liquid chromatographic analysis of products and remaining nonacetylated substrate. The highest specific activities were observed in Balsam pear which contained 17.37 ± 1.45 N-acetyl aminofluorene nmole/min/mg protein and 46.27 ± 6.87 N-acetyl p-aminobenzoic acid nmole/min/mg protein. N-acetyltransferase activities within the remaining 57 foodstuffs analyzed ranged from none detected to 3.39 ± 0.72 N-acetyl aminofluorene nmole/min/mg protein and none detected to 32.45 ± 6.55 N-acetyl p-aminobenzoic acid nmole/min/mg protein. This is the first demonstration of acetyl CoA: arylamine N-acetyltransferase activity in common foodstuffs.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号