全文获取类型
收费全文 | 955篇 |
免费 | 2篇 |
专业分类
电工技术 | 10篇 |
综合类 | 1篇 |
化学工业 | 103篇 |
金属工艺 | 14篇 |
机械仪表 | 9篇 |
矿业工程 | 5篇 |
轻工业 | 2篇 |
水利工程 | 12篇 |
石油天然气 | 43篇 |
无线电 | 8篇 |
一般工业技术 | 135篇 |
冶金工业 | 599篇 |
原子能技术 | 8篇 |
自动化技术 | 8篇 |
出版年
2022年 | 9篇 |
2019年 | 7篇 |
2018年 | 5篇 |
2017年 | 7篇 |
2016年 | 16篇 |
2014年 | 12篇 |
2013年 | 15篇 |
2012年 | 10篇 |
2011年 | 17篇 |
2010年 | 9篇 |
2009年 | 8篇 |
2008年 | 11篇 |
2007年 | 10篇 |
2006年 | 12篇 |
2005年 | 8篇 |
2004年 | 6篇 |
2003年 | 11篇 |
2002年 | 7篇 |
2001年 | 11篇 |
2000年 | 6篇 |
1999年 | 10篇 |
1998年 | 130篇 |
1997年 | 96篇 |
1996年 | 90篇 |
1995年 | 54篇 |
1994年 | 33篇 |
1993年 | 33篇 |
1992年 | 11篇 |
1991年 | 10篇 |
1990年 | 15篇 |
1989年 | 8篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 13篇 |
1985年 | 11篇 |
1983年 | 6篇 |
1982年 | 10篇 |
1981年 | 10篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 11篇 |
1977年 | 31篇 |
1976年 | 81篇 |
1975年 | 7篇 |
1974年 | 8篇 |
1973年 | 10篇 |
1972年 | 4篇 |
1971年 | 5篇 |
1970年 | 7篇 |
1967年 | 7篇 |
排序方式: 共有957条查询结果,搜索用时 0 毫秒
1.
I. A. Grishin V. A. Gur'ev E. B. Intyushin Yu. E. Elliev A. P. Savikin 《Inorganic Materials》2004,40(4):431-433
TeO2–WO3 glasses coactivated with Er3+ and Yb3+ are prepared. The effect of Yb content on the efficiency of Er photoluminescence (PL) in the visible and IR spectral regions is studied. The highest PL efficiency is achieved at an Er : Yb atomic ratio of 1 : 1. The PL lifetime for the Er3+
4
I
13/2 level is determined to be 7–9 ms. 相似文献
2.
Cross-linking additions of silicon carbide and waste material from ferroalloy production make it possible to increase the
heat-resistance index for mullite-containing refractories. For briquette specimens based on a charge containing aluminum powder
it reaches 45 thermal cycles (1300°C – water).
Translated from Novye Ogneupory, No. 11, pp. 44–46, November 2008. 相似文献
3.
Yu. A. Radin I. A. Grishin T. S. Kontorovich O. B. Panshina A. V. Chugin 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2006,40(2):113-119
Problems arising with connecting the second exhaust-heat boiler to the first exhaust-heat boiler under load in the case of
flow circuits of combined-cycle plants of type PGU-450 are considered. Similar problems exist for two-boiler single-turbine
units of type PGU-325 and for two-boiler single-turbine units of traditional steampower plants with an output of 200–300 MW
upon connection of the second furnace of a two-furnace boiler to the operating first furnace. Analysis of the temperature-induced
stressed state and of the cyclic strength of thick-walled elements of the steam-water conduit of PGU-450 and of two-furnace
boilers of two-boiler single-turbine units with an output of 200–300 MW (the check valve, the inlet header of the water economizer)
is used for determining the steam temperature differences in the high-pressure conduits to the steam turbine and the order
of connection of the second exhaust-heat boiler to the operating fist one. Modes of enabling a two-boiler single-turbine unit
of a combined-cycle plant, which are most “rigid” from the standpoint of thermal strength, are determined.
__________
Translated from élektricheskie Stantsii, No. 2, February 2006, pp. 11–17. 相似文献
4.
Z Dimitrova Dimitrova VG Dumanov G Ivanova Petrova 《Canadian Metallurgical Quarterly》1997,67(2-3):73-79
Registered psychiatric morbidity in Bulgaria as a whole and particularly in Plovdiv, the second largest region of the country, was assessed. Three aspects of psychotropic drug usage were analysed, namely, changes in registered psychotropic drugs, the prescribed daily dose (PDD) values for 2 years, and the preferred therapeutic schemes, and drug usage and needs in a psychiatric hospital with 365 beds. This was done by time series analysis for evaluation of psychiatric morbidity and drug consumption data, calculation of PDD for psychotropic medicines, and, based on a modification of the World Health Organization's morbidity method, assessment and prediction of drug use and needs in Plovdiv hospital. The results indicated that the registered morbidity had increased by 4% over the period 1989-93 to 2,427 psychiatric patients per 100,000 people. The increased consumption of especially benzodiazepines and sedative medicines was analyzed. Diazepam was prescribed the most often (91.1%), followed by levomepromazine (86.4%), haloperidol (82.7%), etc. Future drug consumption in Plovdiv hospital is expected to decrease because therapeutic practice in hospitals has been revised and improved on the basis of the World Health Organization's recommendations. 相似文献
5.
6.
7.
The possibility that progesterone or estradiol may regulate expression of G protein in the rat myometrium during the course of pregnancy has been investigated using 1) immunoblot analysis of Gi2 alpha, Gi3 alpha, and Gq alpha subunits and 2) hybridization blot analysis of subunit mRNA. Eighteen hours after administration, estradiol had significantly increased the levels of both Gi2 alpha subunit and Gi2 alpha mRNA (by 40% and 32%, respectively). In control pregnant rats, we observed similar changes at the end of pregnancy, when myometrial concentrations of estradiol had increased, i.e., a 41% increase in immunoreactive Gi2 alpha subunit that correlated with a parallel 45% increase in mRNA levels. In contrast, levels of immunoreactive Gi3 alpha subunit and mRNA, which decreased with advancing gestation, were not influenced by estradiol or progesterone administration. Progesterone administration resulted 30 h later in a significantly decreased level of Gq alpha immunoreactivity (32%) and Gq alpha mRNA (30%). In control rats, Gq alpha protein and mRNA were also significantly lower at midpregnancy under progesterone dominance vs. term. At this stage, a twofold increase in Gq alpha subunit correlated with a 40% increase in mRNA levels. These results demonstrate that myometrial Gi2 alpha and Gq alpha subunits are physiological targets for estradiol and progesterone, respectively, in vivo. Alterations of these G protein levels are discussed in relation to their mediating effects on adenylyl cyclase activity or the phospholipase C pathway during the course of pregnancy. 相似文献
8.
Evaluation of humoral immune responses in cattle grazing endophyte-infected or endophyte-free fescue
RL Rice DJ Blodgett GG Schurig WS Swecker JP Fontenot VG Allen RM Akers 《Canadian Metallurgical Quarterly》1997,59(3-4):285-291
Anecdotal reports suggest cattle with fescue toxicosis may not respond to vaccination and thus, experience increased incidence of Bovine Respiratory Disease Complex (BRDC) when shipped to feedlots. Fescue toxicosis causes hypoprolactemia in cattle. Hypoprolactemia decreases humoral immune responses in mice. Therefore, a study was conducted to compare the magnitude of primary and secondary humoral immune responses against specific antigens in cattle grazing endophyte-infected or endophyte-free fescue. Angus steers were blocked by weight and allocated into four groups. Two groups grazed endophyte-infected (EI) fescue and the other two groups grazed endophyte-free (EF) fescue. All steers were injected IM on d 0 and 21 with lysozyme without adjuvant and concanavalin. A (Con A) with sheep red blood cells (SRBC) in incomplete adjuvant of Freund. Steers were bled on days 0, 21 and 35 post-vaccination. Average daily gains (ADG), alkaline phosphatase (ALP) activity, cholesterol concentrations, rectal temperatures, and serum prolactin concentrations were measured to confirm fescue toxicosis in steers grazing EI fescue. Antibodies to Con A and SRBC were determined by ELISA and hemagglutination assay, respectively. The ADG were decreased for the EI group during the first month. Rectal temperature were elevated and serum prolactin concentrations were decreased in the EI group. Cholesterol and ALP concentrations also were decreased in the EI group. Primary and secondary immune responses against Con A tended to be increased and were increased against SRBC in the EI group. Antibodies against lysozyme were not induced in either group. In conclusion, cattle grazing EI fescue mounted similar humoral immune responses to vaccination, despite hypoprolactemia, as cattle grazing EF fescue. Increases in bovine respiratory disease in cattle maintained on EI fescue probably is not associated with lack of humoral immune response to vaccination protocols as a result of fescue toxicosis. 相似文献
9.
Three models of cancerogenesis were used to test the anti-cancerogenic effects of pentoxiphylline. In female rats, breast adenocarcinoma was induced by intramammary injections of N-methyl-N-nitrosourea (MNU) or colonic and rectal adenocarcinomas by intrarectal instillations of MNU. In female mice, squamous cell carcinomas of the cervix uteri and vagina were induced by intravaginal applications of 7,12-dimethyl-benz(a) anthracene (DMBA). Pentoxifylline was given with drinking water at a concentration of 500 mg/l long at the stage of carcinogenesis promotion/progression. Pentoxifylline exerted a strong inhibitory effect on the development of mammary tumors and a moderate inhibitory effect on the development of colonic and rectal tumors induced by MNU in rats. However, the drug did not affect the development of cervical and vaginal tumors caused by DMBA in mice. 相似文献
10.