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   3059篇
  免费   4篇
电工技术   3篇
化学工业   13篇
金属工艺   6篇
机械仪表   1篇
建筑科学   9篇
矿业工程   6篇
能源动力   6篇
轻工业   220篇
石油天然气   2篇
无线电   36篇
一般工业技术   26篇
冶金工业   2725篇
原子能技术   1篇
自动化技术   9篇
  2019年   3篇
  2017年   3篇
  2016年   2篇
  2015年   2篇
  2014年   10篇
  2013年   14篇
  2012年   2篇
  2011年   6篇
  2010年   5篇
  2009年   6篇
  2008年   16篇
  2007年   16篇
  2006年   9篇
  2005年   14篇
  2004年   18篇
  2003年   16篇
  2002年   25篇
  2001年   9篇
  2000年   29篇
  1999年   114篇
  1998年   845篇
  1997年   489篇
  1996年   297篇
  1995年   154篇
  1994年   147篇
  1993年   184篇
  1992年   22篇
  1991年   35篇
  1990年   48篇
  1989年   45篇
  1988年   42篇
  1987年   34篇
  1986年   27篇
  1985年   25篇
  1984年   3篇
  1983年   6篇
  1982年   8篇
  1981年   15篇
  1980年   34篇
  1979年   4篇
  1978年   4篇
  1977年   72篇
  1976年   184篇
  1975年   5篇
  1974年   4篇
  1970年   2篇
  1968年   2篇
  1964年   1篇
  1961年   1篇
  1955年   2篇
排序方式: 共有3063条查询结果,搜索用时 46 毫秒
971.
972.
973.
A survey of the cestode infections of 304 dogs from 134 properties in the Albany area of Western Australia was performed. Purgation was induced by oral administration of arecoline and the purge examined for cestodes. The cestodes found and their infection rates were: Dipylidium caninum 16.4%; Taenia spp 36.5%; T. ovis 8.9%; T. hydatigena 15.1%; T. pisiformis 15.1%; T. serialis 2.3%; Echinococcus granulosus 0.7%; Questionnaires completed on 133 of the 134 properties at the time the dogs were purged showed that:--73.6% of farmers were feeding raw sheep-meat and 24.8% were feeding raw offal to their dogs; dogs were treated on a regular basis with a cestocide on 23.3% of properties; dogs were allowed to roam on 21.8% of the properties and stray dogs were considered prevalent on 23.3% of properties. Suggestions for control of Cysticercus ovis are made based on an interpretation of the significance of these findings.  相似文献   
974.
975.
The differential role of various body attitudes in predicting the self-concepts of late adolescents (124 males and 218 females), enrolled in introductory psychology courses, was assessed. Subjects rated 24 body characteristics in terms of 1) how physically attractive they assumed these parts of their bodies were, and 2) how physically effective they assumed them to be; subjects also responded to a short self-concept scale. In accordance with the theory of Erikson (1968) and of McCandless (1970), it was expected that attractiveness attitudes should contribute more to the self-concepts of females than should effectiveness attitudes, while a reverse pattern of interrelatedness was expected for males. Results indicated a higher correspondence between what are seen as attractive body parts and what are viewed as effective body components for males than for females. Moreover, findings from step-wise multiple regression analyses of each sex group's ratings of the body parts for attractiveness and effectiveness, respectively, each with the criterion variable constituting mean self-concept score, were consistent with expectations. For females, the multiple correlation between attractiveness ratings and self-concept was greater than the multiple correlation between effectiveness ratings and self-concept, and more attractiveness variables than effectiveness variables were significant predictors of self-concept. The converse of these findings were obtained with the males' data. The relevance of these results for theories of personality development were discussed.  相似文献   
976.
Piglets aged 6 days were rendered uremic by subtotal nephrectomy and their growth and dietary intakes studied over the next 21 days. Eleven control piglets fed a voluntary intake of a sow's milk substitute (group A), 11 nephrectomized piglets fed a voluntary intake of the same feed (group B), 6 nephrectomized piglets tube fed the same milk (group C), and 11 nephrectomized piglets fed a voluntary intake of a low protein, isocaloric food (group D) were studied. After nephrectomy the piglets had an initial rapid rise in blood urea concentration which had fallen by day 7 and then leveled out around 13 mmol/liter in group B and 8 mmol/liter in group D. After operation control piglets (group A) ate more from day 4 and were larger from day 7 than the nephrectomized piglets (group B). Those piglets tube fed (group C) were of a similar size to the controls but all died between day 7 and day 11 with associated high blood urea concentrations. Piglets fed the low protein, isocaloric feed (group D) were smaller than both the controls and group B. They also ate less food than the controls and those nephrectomized piglets in group B which were on a voluntary intake of the normal feed.  相似文献   
977.
Plasma immunoreactive glucagon (IRG) concentrations were measured in 36 patients with chronic renal failure (CRF) and 32 normal subjects. In addition, the components of circulating IRG were analyzed by gel filtration in the fasting state and after physiological stimuli. Fasting IRG was elevated (P less than 0.001) in CRF patients (534 +/- 32 pg/ml) compared with the levels found in healthy subjects (113 +/- 9 pg/ml). Oral glucose suppressed plasma IRG in CRF patients from a basal level of 568 +/- 52 to a nadir of 354 +/- 57 pg/ml (120 min). This degree of suppression (38%) was comparable to that found in normal subjects (basal = 154 +/- 20 to 100 +/- 23 pg/ml) at 120 min (35%). Intravenous infusion of arginine (250 mg/kg) resulted in a 71% rise in IRG in CRF patients and a 166% increase in normal subjects. Gel filtration of fasting plasma from CRF patients showed three major peaks. The earliest (A) was found in the void volume (mol wt greater than 40,000) and constituted 16.5 +/- 4.7% of the elution profile. The middle peak (B) eluted just beyond the proinsulin marker (approximately 9,000 mol wt) and constituted the largest proportion of the elution profile (56.5 +/- 3.4%). The third peak (C) coincided with the standard glucagon and [125I]glucagon markers (3,485 mol wt) and comprised 27.0 +/- 4% of the IRG profile. In contrast, only peaks A and C were found in fasting plasma of normal subjects (53.6 +/- 10.4% in A and 46.4 +/- 10.4 in C). After oral glucose, glucagon immunoreactivity in the 3,500 mol wt peak (C) was markedly suppressed, while the B peak in patients with CRF declined to a lesser extent. The A peak in both groups was unchanged. After an arginine infusion only the C peak increased in both groups of subjects. Gel filtration of plasma in 3 M acetic acid gave similar profiles to those obtained in glycine albumin buffer. Exposure of serum to trypsin indicated that the B and C peaks were digestible, while the A peak was resistant to the action of the enzyme. In one sample, peak C increased after a 2-h exposure of serum to trypsin. We conclude that circulating IRG in normal subjects and patients with CRF is heterogenous. The hyperglucagonemia of renal failure is largely due to an increase in IRG material of approximately 9,000 mol wt, consistent with proglucagon, although the 3,500 mol wt component is also considerably elevated (threefold). The significance of circulating IRG levels should be interpreted with caution until the relative biological activity of the three components is established.  相似文献   
978.
Delegation     
The three basic elements of delegation (responsibility, authority and accountability) are discussed with regard to effective management. Major guidelines for effective delegation are noted, including: (1) securing a mutual commitment to responsibilities involved; (2) establishing goals and checkpoints; (3) giving appropriate authority to the delegate; and (4) avoiding by-passing the delegate.  相似文献   
979.
980.
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