全文获取类型
收费全文 | 126篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 10篇 |
金属工艺 | 3篇 |
机械仪表 | 1篇 |
建筑科学 | 2篇 |
能源动力 | 2篇 |
轻工业 | 23篇 |
水利工程 | 4篇 |
无线电 | 5篇 |
一般工业技术 | 9篇 |
冶金工业 | 51篇 |
原子能技术 | 1篇 |
自动化技术 | 13篇 |
出版年
2022年 | 2篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2014年 | 1篇 |
2013年 | 1篇 |
2012年 | 3篇 |
2011年 | 3篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 3篇 |
2007年 | 2篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 8篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 7篇 |
1997年 | 7篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1965年 | 2篇 |
1959年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有129条查询结果,搜索用时 15 毫秒
1.
Prostate enlargement in mice due to fetal exposure to low doses of estradiol or diethylstilbestrol and opposite effects at high doses 总被引:7,自引:0,他引:7
FS vom Saal BG Timms MM Montano P Palanza KA Thayer SC Nagel MD Dhar VK Ganjam S Parmigiani WV Welshons 《Canadian Metallurgical Quarterly》1997,94(5):2056-2061
On the basis of results of studies using high doses of estrogens, exposure to estrogen during fetal life is known to inhibit prostate development. However, it is recognized in endocrinology that low concentrations of a hormone can stimulate a tissue, while high concentrations can have the opposite effect. We report here that a 50% increase in free-serum estradiol in male mouse fetuses (released by a maternal Silastic estradiol implant) induced a 40% increase in the number of developing prostatic glands during fetal life; subsequently, in adulthood, the number of prostatic androgen receptors per cell was permanently increased by 2-fold, and the prostate was enlarged by 30% (due to hyperplasia) relative to untreated males. However, as the free serum estradiol concentration in male fetuses was increased from 2- to 8-fold, adult prostate weight decreased relative to males exposed to the 50% increase in estradiol. As a model for fetal exposure to man-made estrogens, pregnant mice were fed diethylstilbestrol (DES) from gestation days 11 to 17. Relative to controls, DES doses of 0.02, 0.2, and 2.0 ng per g of body weight per day increased adult prostate weight, whereas a 200-ng-per-g dose decreased adult prostate weight in male offspring. Our findings suggest that a small increase in estrogen may modulate the action of androgen in regulating prostate differentiation, resulting in a permanent increase in prostatic androgen receptors and prostate size. For both estradiol and DES, prostate weight first increased then decreased with dose, resulting in an inverted-U dose-response relationship. 相似文献
2.
3.
The utility of heart-rate variability (HRV) to index important aspects of neural control of the heart has made it one of the most valuable tools for researchers interested in health and behavior. However, most of the literature and extant data on the central origins of HRV have been derived from animal models. As yet little is known about the central nervous system (CNS) origins and concomitants in humans. In the following we will briefly detail a set of neural structures that have been associated with important CNS functions including cardiac regulation and emotional regulation. We will briefly summarize recent data using pharmacological, neuroimaging, and psychophysiological techniques that have examined CNS concomitants of HRV especially during emotion. Based on these and other data will we report the results of a computational model that examined the interactions of several neural structures and their effect on emotion-related HRV. 相似文献
4.
Wanjun Liu Kelby Thayer Manjusri Misra Lawrence T. Drzal Amar K. Mohanty 《Polymer Engineering and Science》2007,47(7):969-976
Big blue stem grass fiber-reinforced high density polyethylene powder biocomposites were fabricated using two separate processing schemes: (1) by compounding biofiber with the thermoplastic powder in an extruder and subsequently injection molding the extrusion pellets and (2) by combining biofiber and the powder thermoplastic powder using a modified sheet molding compounding (SMC) line and subsequently compression molding the sheet material. The physical properties including storage modulus, heat deflection temperature (HDT), notched Izod impact strength, and morphology were evaluated with dynamic mechanical analysis, Izod impact strength measurement, and microscopy observation. It was found that compression-molded specimens achieved similar modulus values to injection molded specimens for grass-reinforced high density polyethylene (HDPE) composites. The stiffness of the compression-molded specimens is related to the consolidation state of the samples, which depends on compression molding conditions such as temperature, pressure, and mold type. Compression-molded specimens exhibited a higher HDT and notched Izod impact strength compared to injection-molded samples. Grass fiber-reinforced cellulose acetate butyrate (CAB) biocomposites made with SMC processing had similar physical properties with grass fiber-reinforced HDPE composites, which indicates that natural fiber-reinforced CAB biocomposites have the potential to replace polyolefin-based composites for automotive applications. POLYM. ENG. SCI. 47:969–976, 2007. © 2007 Society of Plastics Engineers. 相似文献
5.
Applying system engineering principles specifically to the development of large, complex software systems provides a powerful tool for process and product management. The application of system engineering principles to the development of a computer software system produces activities, tasks, and procedures called software system engineering, or SwSE. Many practitioners consider SwSE to be a special case of system engineering, and others consider it to be part of software engineering. However, we can argue that SwSE is a distinct and powerful tool for managing the technical development of large software projects. The article integrates the definitions and processes from the IEEE software engineering standards into the SwSE process 相似文献
6.
FS vom Saal PS Cooke DL Buchanan P Palanza KA Thayer SC Nagel S Parmigiani WV Welshons 《Canadian Metallurgical Quarterly》1998,14(1-2):239-260
Two chemicals previously shown to have estrogenic activity, bisphenol A and octylphenol, were examined for their effects on accessory reproductive organs and daily sperm production in male offspring of mice fed these chemicals during pregnancy. These chemicals are used in the manufacture of plastics and other products, and have been detected in food and water consumed by animals and people. From gestation day 11-17 female mice were fed an average concentration (dissolved in oil) of bisphenol A or octylphenol of 2 ng/g body weight (2 ppb) and 20 ng/g (20 ppb). The 2 ppb dose of bisphenol A is lower than the amount reported to be swallowed during the first hour after application of a plastic dental sealant (up to 931 micrograms; 13.3 ppb in a 70 kg adult). We found that the 2 ng/g dose of bisphenol A permanently increased the size of the preputial glands, but reduced the size of the epididymides; these organs develop from different embryonic tissues. At 20 ng/g, bisphenol A significantly decreased efficiency of sperm production (daily sperm production per g testis) by 20% relative to control males. The only significant effect of octylphenol was a reduction in daily sperm production and efficiency of sperm production at the 2 ng/g dose. A new approach to studying physiologically relevant doses of environmental endocrine disruptors is discussed, particularly with regard to the development of the reproductive organs, the brain, and behavior. 相似文献
7.
Thayer Scudder 《国际水资源开发杂志》2001,17(3):329-341
Responding to the unanimous recommendation of a multi-stakeholder workshop, the creation of the World Commission on Dams (WCD) was formally announced in February 1998. Financially supported by 53 public, private and civil society agencies, the twelve Commissioners released the WCD Final Report in London in November 2000. In this article a former Commissioner discusses the "WCD process" from its origin to the present. The contents of the final report are described, with special attention paid to the significance of the WCD's rights and risks approach as a first step toward a new development paradigm for an increasingly global, 21st century society. 相似文献
8.
Chapman Christopher L.; Baker Elizabeth L.; Porter Greg; Thayer Stephen D.; Burlingame Gary M. 《Canadian Metallurgical Quarterly》2010,14(1):15
The present study seeks to establish the validity of the Group Psychotherapy Intervention Rating Scale (GPIRS), an observer-rated measure of the quality of group leader interventions. Concurrent validity was tested by comparing GPIRS results to 2 group gold standard process measures, the Hill Interaction Matrix and the Group Climate Questionnaire. Significant correlations between leader intervention scores and group member perceptions of group climate, as well as verbal interaction scores, were found. In addition, results indicated correlations between interventions aimed to gain balance between confrontation and warmth and member-rated levels of cohesion. Results lend support for the concurrent validity of the GPIRS. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
Foods can be treated with gamma radiation, a nonthermal food process, to inactivate foodborne pathogens and fungi, to kill insects on or in fruits and vegetables, and to increase shelf life. Gamma irradiation is especially well suited for these treatments because of its ability to penetrate commercial pallets of foods. Irradiated fruits, vegetables, poultry, and hamburger have been received favorably by the public and are now available in supermarkets. The use of irradiation on fresh alfalfa sprouts was studied to determine its effect on keeping quality as related to aerobic microbial load. After an irradiation dose of 2 kGy, the total aerobic count decreased from 10(5-8) to 10(3-5) CFU/g, and the total coliform counts decreased from 10(5-8) to 10(3-0) CFU/g. The results showed that the sprouts maintained their structure after irradiation, and the keeping quality was extended to 21 days, which is an increase of 10 days from the usual shelf life. The effect of various doses of irradiation on alfalfa seeds as measured by percent germination and yield ratio (wt/wt) of sprouts was determined. There was little effect on the percent germination, but as the dose increased, the yield ratio of alfalfa sprouts decreased. As the length of growing time increased, so did the yield ratio of the lower dose irradiated seeds (1 to 2 kGy). The irradiation process can be used to increase the shelf life of alfalfa sprouts, and irradiating alfalfa seeds at doses up to 2 kGy does not unacceptably decrease the yield ratio for production of alfalfa sprouts. 相似文献
10.
McCarroll James E.; Thayer Laurie E.; Liu Xian; Newby John H.; Norwood Ann E.; Fullerton Carol S.; Ursano Robert J. 《Canadian Metallurgical Quarterly》2000,68(3):521
Recidivism by spouse abusers was investigated using records of offenders in the U.S. Army Central Registry. Recidivism by gender and military status (active-duty or civilian spouse) was compared over a 70-month period. Between fiscal years 1989–1997, 48,330 offenders were identified in initial and recidivist incidents. Recidivism was analyzed by means of a Cox proportional hazard rate model, controlling for age, race, number of dependents, education, and substance abuse. Two different sets of survival curves were obtained: (a) Men were much more likely than women to have a recurrence and (b) within gender, civilians were more likely to have a recurrence than were active-duty military personnel. At 70 months, 30% of the male civilian offenders and 27% of the male active-duty offenders had committed a subsequent spouse abuse incident compared with 20% of the female civilian offenders and 18% of the female active-duty offenders, controlling for other variables. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献