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   110篇
  免费   0篇
电工技术   7篇
化学工业   10篇
金属工艺   1篇
机械仪表   3篇
建筑科学   2篇
能源动力   2篇
轻工业   13篇
无线电   8篇
一般工业技术   12篇
冶金工业   40篇
原子能技术   2篇
自动化技术   10篇
  2021年   1篇
  2019年   1篇
  2014年   2篇
  2013年   6篇
  2012年   1篇
  2011年   7篇
  2010年   1篇
  2009年   3篇
  2008年   5篇
  2007年   5篇
  2006年   6篇
  2005年   2篇
  2004年   5篇
  2003年   3篇
  2002年   1篇
  2001年   3篇
  2000年   1篇
  1999年   3篇
  1998年   16篇
  1997年   6篇
  1996年   3篇
  1995年   3篇
  1994年   8篇
  1993年   5篇
  1992年   3篇
  1987年   1篇
  1986年   1篇
  1985年   2篇
  1983年   1篇
  1982年   1篇
  1979年   1篇
  1977年   1篇
  1976年   1篇
  1973年   1篇
排序方式: 共有110条查询结果,搜索用时 15 毫秒
1.
目的:研究大米分离蛋白和大豆分离蛋白对因雌性激素缺乏引起的高胆固醇血症的影响.方法:将24只Wistar成年雌鼠随机分为4组.3组大鼠进行双侧卵巢切除手术,分别喂食添加20%酪蛋白(对照组)、大米分离蛋白或大豆分离蛋白的饲料.另1组进行卵巢伪切除手术,喂食添加20%酪蛋白的对照饲料,喂养4周后解剖,测定血清和肝脏中胆固醇、甘油三酯浓度以及粪中胆汁酸排泄量和蛋白表观消化率等指标.结果:卵巢切除明显增加成年雌鼠血清和肝脏中胆固醇和甘油三酯浓度.与酪蛋白组相比,饲料中添加大豆分离蛋白能显著降低卵巢切除大鼠血浆总胆固醇和低密度脂蛋白及胆固醇浓度(p<0.05),但对血浆甘油三酯浓度无显著影响,同时明显降低肝重、肝脏中总脂、总胆固醇、游离胆固醇及甘油三酯总量,以及增加排粪量和胆汁酸排泄量,大豆分离蛋白表观消化率也明显比酪蛋白和大米分离蛋白高.大米分离蛋白对血脂没有明显降低效果,但肝脏总脂、总胆固醇、游离胆固醇和甘油三酯浓度明显低于酪蛋白饲料组,而排粪量、粪中胆汁酸排泄量和蛋白表观消化率则与酪蛋白组无显著差异.结论:抗消化蛋白对因雌性激素缺乏引起的高胆固醇血症有明显降低效果,可能的作用机制是由于该蛋白的低消化性干扰,肠道中胆汁酸代谢,增加粪中胆汁酸的排泄量来降低肝脏和血浆中胆固醇浓度.  相似文献   
2.
ABSTRACT:  The effect of dietary high-amylose corn starch (HACS) of varying dietary fiber (DF) content on plasma cholesterol was examined in ovariectomized (OVX) rats. Gelatinized normal corn starch (G-CS) was used as a reference. OVX rats were fed a fiber-free purified diet containing G-CS, HACS, gelatinized high-amylose corn starch (G-HACS), or heat-moisture treated HACS (HM-HACS) at 400 g starch/kg diet for 21 d. The DF content of G-CS, HACS, G-HACS, and HM-HACS measured by the AOAC method was 0.1, 19.3, 2.4, and 64.5 g/100 g, respectively. The dry weight of cecal contents, cecal wall weight, the amount of short chain fatty acids in cecal contents, the amount of bile acids in small intestinal contents, and fecal excretion of neutral sterols increased logarithmically with increasing DF, while total plasma cholesterol concentration decreased. On the other hand, hepatic CYP7A1 activity, fecal dry weight, and fecal excretion of bile acids increased linearly with increasing DF, while body weight gain decreased. The hypocholesterolemic effect of HACS in OVX-rats appeared to be more effective by heat-moisture treatment.  相似文献   
3.
The physiological effects of hydroxypropyl‐distarch phosphate (HDP) were examined in rats. Male rats were fed a fiber‐free purified diet containing gelatinized potato starch (PS, 50 g/kg diet) that was not modified chemically or gelatinized, chemically modified potato starch (CMS, 50 g/kg diet) for 21 d. PS was used as the control. Six kinds of gelatinized HDP from potato with 2 different degrees of hydroxypropylation and 3 different degrees of cross‐linking were used as CMS. The wet weight and moisture of the fecal output of the rats fed highly hydroxypropylated HDP was 70% and 30% greater, respectively, than that in the control rats. The weights of the cecal wall and content of the rats fed highly hydroxypropylated HDP were 15% and 30% higher, respectively, than those of the control rats. The apparent absorption of Mg was 15% higher in the rats fed highly hydroxypropylated HDP than in the control rats. On the other hand, the apparent absorptions of Ca, Zn, and Fe were not affected by the diet. Cross‐linking did not influence the above‐mentioned physiological effects of HDP. Fecal excretion of bile acids and the plasma cholesterol concentration were not affected by the diet. These results show that the physiological effects of HDP depend on the hydroxypropylation but not the cross‐linking.  相似文献   
4.
The microscopic mechanism of grain boundary (GB) embrittlement in metals by hydrogen segregation (trapping) has been not well understood for many years. From first-principles calculations, we show here that the calculated cohesive energy of bcc Fe Σ3(111) and fcc Al(Cu) Σ5(012) symmetrical tilt GBs can be significantly reduced if many hydrogen atoms segregate at the GBs. This indicates that the reduction of the cohesive energy of the GB may cause the hydrogen-induced GB embrittlement in Fe, Al, and Cu. Considering the “mobile” effect of hydrogen during fracture, especially for the Fe system, more hydrogen atoms coming from solid solution state can segregate on the gradually formed two fracture surfaces and reduce further the cohesive energy. We suggest a new idea about the upper and lower critical stresses observed in the constant-load test of hydrogen-induced delayed fracture in high-strength steels; the upper critical stress is determined by the amount (density) of “immobile” hydrogen atoms segregated at the GB before fracture, and the lower critical stress is determined by the total amount (density) of immobile and mobile hydrogen atoms, the latter of which segregate on the two fracture surfaces during fracture.  相似文献   
5.
The virtual metamorphosis system lets people change their forms into any other form in a virtual scene. To realize these changes, a computer vision system estimates facial expressions and body postures and reproduces them in a computer graphics avatar in real time. We introduce three systems in order of their development: the Virtual Kabuki system, Networked Theater and “Shall We Dance?”  相似文献   
6.
For the treatment of hypertension, the combination of an angiotensin-converting enzyme (ACE) inhibitor and a thiazide diuretic is supported by multiple lines of evidence, because these drugs have synergistic action and are expected to cancel out each other's adverse side effects. However, the long-term outcome of this combination antihypertensive therapy is not entirely clear. In the present multicenter open trial, we investigated the long-term efficacy and safety of combined antihypertensive therapy with an ACE inhibitor, lisinopril, and a thiazide diuretic, trichlormethiazide. A total of 466 patients with essential hypertension were treated with lisinopril alone (monotherapy group, n = 360) or with a combination of lisinopril with trichlormethiazide (combination therapy group, n = 106) for 1 year. The average blood pressure was effectively lowered to below 150/90 mmHg in both the monotherapy and the combination therapy groups throughout the study period. The average maintenance dose of lisinopril was lower when combined with thiazide than when given alone (9.8 vs. 11.5 mg/day, p < 0.001). Dry cough was the major side effect of lisinopril; no severe adverse effects were observed. The incidence of cough was not significantly different between the monotherapy group (13.1%) and the combination therapy group (11.3%). The increase in serum potassium observed in the monotherapy group was reversed by the concurrent use of the thiazide diuretic in the combination therapy group. Fasting blood glucose was significantly reduced in the monotherapy group; the reduction observed in the combination therapy group was not significant. Thus, the present results provide useful information as to the effectiveness and safety of combined antihypertensive therapy with lisinopril and a thiazide in comparison with monotherapy with lisinopril.  相似文献   
7.
Rapid demographic aging has made caring for the elderly an increasingly important social issue in Japan. To study current conditions of the oldest elderly citizens, we investigated the dietary practices of centenarians in the Tokyo metropolitan area. First, we compared the food intake of centenarians with that of octogenarians. Next, to identify dietary trends, we investigated whether food intake by centenarians had changed significantly between 1981 and 1995. Nutritional intake by the centenarians and octogenarians in 1995 was about 60% and 75% that of the control, respectively. However, the nutritional intake of well nourished centenarians was similar to that of the octogenarians. Cognitive function and daily activity have an influence on nutritional intake. The centenarians were similar to the control subjects in their consumption of dairy products, sweets, and fruit. However, their intake of cereals, meat, fish, and fatty oils was loss than 60% that of the control, which indicates their preference for soft and sugary foods. The pattern of dietary practices of centenarians in 1981 was similar. Although the total food intake of centenarians amounted to 60% of the control in 1995 energy intake per kilogram of body weight averaged over 30 kcal. As to dietary trends, centenarians in 1981 are more cereals, eggs, algae products, and legumes than did their 1995 counterparts. This finding seems to reflect a generational difference in dietary habits.  相似文献   
8.
This paper describes the improvements in launching stability and launching velocity of the linear accelerator (LAC). The authors have designed and produced a railgun using the LAC for weaving loom shuttles. The LAC is an electromagnetic launcher which enables a projectile to be launched at a speed of more than 50 m/s. Basically, it consists of a unipole linear dc motor and operates the same principle as dc rotary motors, the most difficult problem in this system being the stabilization of the current collection on the projectile. Then, various launch experiments have been conducted. As a result, the carbon projectile was launched at a speed of 73 m/s using double-state-type LAC.  相似文献   
9.
Many imidazole derivatives are shown to inhibit adrenal steroid biosynthesis. The present study was undertaken to examine an effect of another imidazole derivative, losartan (an angiotensin II receptor antagonist), on responses of cortisol and aldosterone to adrenocorticotrophic hormone (ACTH). Nine patients with essential hypertension were given placebo orally for 7 days and 50 mg of losartan for the next 9 days. Response of serum cortisol and plasma aldosterone to intramuscular ACTH injection were determined before and at the end of the treatment with losartan. Serum cortisol and plasma aldosterone significantly increased after ACTH injection in both periods of treatment (placebo and losartan). The increments in these parameters during treatment with losartan were not significantly different from those during treatment with placebo. These results suggest that the inhibitory effect of losartan on adrenal steroid biosynthesis is negligible.  相似文献   
10.
The synergistic action of antimony (Sb) with bromine (Br) was studied for polypropylene-2,3-dibromopropylpentabromophenyl ether–Sb2O3 systems at various Sb/Br molar ratios. Oxygen index, weight loss rate and heating value were used to evaluate the retardant effect. Bromine and antimony emission and their material balances were measured by gravimetric and X-ray fluorometric analysis of heated samples at each reaction time. Retarded HBr formation in the gaseous phase through SbBr3, SbOBr and Sb4O5Br2 was proved by X-ray diffraction analysis of heated residues and model products. SbBr3 and HBr formation were greatest at Sb/Br ratios of 1/3 and 1/4, respectively, while the highest oxygen index and the lowest weight loss rate and heating value were obtained at 1/4. Consequently, HBr will most probably produce the retardant effect rather than SbBr3. Effective synergistic action at the Sb/Br ratio of 1/4 is explained by presuming the formation of an acidic HBr.SbBr3 complex in the molten phase for the particular reaction pattern of bromine in 2,3-dibromopropylpentabromophenyl either.  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