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   2690篇
  免费   1篇
  国内免费   1篇
化学工业   8篇
机械仪表   1篇
建筑科学   4篇
轻工业   6篇
水利工程   2篇
一般工业技术   3篇
冶金工业   2665篇
自动化技术   3篇
  2021年   1篇
  2019年   2篇
  2015年   1篇
  2014年   1篇
  2011年   1篇
  2010年   1篇
  2008年   2篇
  2007年   5篇
  2006年   4篇
  2005年   2篇
  2004年   1篇
  2003年   3篇
  2002年   2篇
  2001年   1篇
  1999年   77篇
  1998年   882篇
  1997年   504篇
  1996年   260篇
  1995年   167篇
  1994年   156篇
  1993年   166篇
  1992年   15篇
  1991年   21篇
  1990年   22篇
  1989年   38篇
  1988年   30篇
  1987年   25篇
  1986年   21篇
  1985年   23篇
  1984年   1篇
  1983年   5篇
  1982年   12篇
  1981年   16篇
  1980年   23篇
  1979年   1篇
  1978年   3篇
  1977年   55篇
  1976年   137篇
  1975年   2篇
  1955年   2篇
  1954年   1篇
排序方式: 共有2692条查询结果,搜索用时 0 毫秒
11.
12.
A family is described in which the mother and 2 of the 5 children had Felty's syndrome, a pattern of inheritance suggesting a dominant defect and one which has not previously been reported. The family is also of interest in that the other sib had rheumatoid arthritis.  相似文献   
13.
Oral vaccination of 19 human adult volunteers with a killed trivalent E. coli vaccine induced an antibody response detectable either in sera and feces. Production of specific IgA immunoglobulins in the intestine was also observed. Antibody titres reached the highest levels 5-10 days after vaccination and were still detectable in the majority of volunteers about 2 months later.  相似文献   
14.
15.
The characteristics of Korean family planning opinion leaders are assessed through a secondary analysis of the 1971 national survey conducted by the Korean Institute for Research in the Behavioral Sciences. In effect, what characterized Korean family planning opinion leaders was a rather national and democratic model. Those who had tried methods, discussed them, and knew a lot about them assumed leadership roles more than others. Place of residence, education, and other such variables mattered relatively little unless a woman had credibility imparted by actual use and knowledge imparted by use or discussions with family planning professionals.  相似文献   
16.
Analysis of data on mental health service providers indicates that in 1971 the private sector accounted for 34% of inpatient days, 86% of outpatient visits, 44% of expenditures by source of funds, and 51% of expenditures by receipt of funds. The author believes that mental health professionals must familiarize themselves with the economic interests influencing national health insurance proposals and with public policy making processes if they are to help preserve appropriate roles for the public and private sectors in mental health service delivery.  相似文献   
17.
Doubt about the role of stretch reflexes in movement and posture control has remained in part because the questions of reflex "usefulness" and the postural "set" have not been adequately considered in the design of experimental paradigms. The intent of this study was to discover the stabilizing role of stretch reflexes acting upon the ankle musculature while human subjects performed stance tasks requiring several different postural "sets". Task specific differences of reflex function were investigated by experiments in which the role of stretch reflexes to stabilize sway doing stance could be altered to be useful, of no use, or inappropriate. Because the system has available a number of alternate inputs to posture (e.g., vestibular and visual), stretch reflex responses were in themselves not necessary to prevent a loss of balance. Nevertheless, 5 out of 12 subjects in this study used long-latency (120 msec) stretch reflexes to help reduce postural sway. Following an unexpected change in the usefulness of stretch reflexes, the 5 subjects progressively altered reflex gain during the succeeding 3-5 trials. Adaptive changes in gain were always in the sense to reduce sway, and therefore could be attenuating or facilitating the reflex response. Comparing subjects using the reflex with those not during so, stretch reflex control resulted in less swaying when the task conditions were unchanging. However, the 5 subjects using reflex controls oftentimes swayed more during the first 3-5 trials after a change, when inappropriate responses were elicited. Four patients with clinically diagnosed cerebellar deficits were studied briefly. Among the stance tasks, their performance was similar to normal in some and significantly poorer in others. Their most significant deficit appeared to be the inability to adapt long-latency reflex gain following changes in the stance task. The study concludes with a discussion of the role of stretch reflexes within a hierarchy of controls ranging from muscle stiffness up to centrally initiated responses.  相似文献   
18.
The activities of certain drug metabolizing enzymes have been measured in liver and kidney slice preparations from domesticated birds. Aminopyrine demethylase activity was significantly lower in liver slices from the duck (Aylesbury X Pekin, Khaki-Campbell) than from the rat (Wistar), and in the Aylesbury X Pekin duck lower than in the turkey (Triple 6 FLX), chicken (Brown Leghorn, Rhode Island Red X Light Sussex) and goose (Emden X Doulouse). The microsomal cytochrome P-450 was lower in duck liver (Aylesbury X Pekin) than in rat liver, and the aniline hydroxylase and aminopyrine demethylase activities in a 10,000 g supernatant fraction of liver were lower in duck preparations (Aylesbury X Pekin, Khaki-Campbell) than rat preparations. These observations suggest that the duck is likely to be susceptible to drugs which are metabolized by the cytochrome P-450 containing mono-oxygenases. UDP-Glucuronyl transferase activity was not detectable in liver and kidney slices from two mature geese. This observation was not the outcome of a deficiency of UDP-glucuronic acid, rapid breakdown of glucuronide by beta-glucuronidase or the presence of a substance inhibitory to UDP-glucuronyl transferase. Liver slices from geese, ducks (Aylesbury X Pekin) and chickens contained low UDP-glucuronyl transferase and high sulphate conjugation enzyme activities, whereas the reverse was found in Khaki-Campbell ducks. The activities of UDP-glucuronyl transferase and the sulphate conjugation enzymes were both relatively high in liver slices from the turkey and rat. The kidney contained lower enzyme activities than the liver except in the duck (Aylesbury X Pekin), in which low activities of aminopyrine demethylase and UDP-glucuronyl transferase were present in slices of both organs. In liver slices from chickens and geese the activities of aminopyrine demethylase and the sulphate conjugation enzymes were similar in mature and immature birds, and the activity of UDP-glucuronyl transferase was considerably higher in chicks and goslings than in mature birds of the same species. In the chick the activities of aminopyrine demethylase, UDP-glucuronyl transferase and the sulphate conjugation enzymes were higher in the duodenum than the remainder of the alimentary tract. The activities of these enzymes in pieces of duodenum were as high as those in slices of liver. The inclusion of sulphate in the incubation medium produced a significant increase in the synthesis of p-nitrophenyl sulphate in liver slices and not kidney slices except those from the duck. The kidney slices seemed to produce sufficient sulphate for the reaction of the sulphate conjugation enzymes to proceed at the maximum rate, but the liver slices did not do so.  相似文献   
19.
Androgen-induced gene activation in the rat prostate   总被引:1,自引:0,他引:1  
  相似文献   
20.
The lordosis response was regularly elicited from 24 of 31 intact, adult male hamsters, using manual somatosensory stimulation of the dorsal rear body. In these males there was no correlation between measures of male-typical behavior and lordosis. Castration had no effect on male lordosis duration scores even when intromissions were eliminated. Combined treatment with estradiol benzoate and progesterone significantly increased male lordosis duration scores. The body surface was mapped with a standardized brush stimulus. For eliciting lordosis, effectiveness of stimulation increased in an almost identical manner for hormone-primed males and females from the anterior to the posterior part of the body, with the stimulation of flanks, rump, and perineum the most effective. Within each skin zone, absolute effectiveness was greater in females than in males. Various types of somato-sensory stimulation were compared for their effectiveness in eliciting lordosis. Females were more responsive to these stimuli than males, even when males were hormonally primed. These behavioral data have implications for concepts of the neural organization of male- and female-typical mating responses existing within the same individual.  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