全文获取类型
收费全文 | 602篇 |
免费 | 3篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 45篇 |
金属工艺 | 34篇 |
机械仪表 | 9篇 |
建筑科学 | 4篇 |
能源动力 | 10篇 |
轻工业 | 84篇 |
水利工程 | 13篇 |
石油天然气 | 2篇 |
无线电 | 20篇 |
一般工业技术 | 57篇 |
冶金工业 | 308篇 |
原子能技术 | 2篇 |
自动化技术 | 14篇 |
出版年
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2014年 | 7篇 |
2013年 | 21篇 |
2012年 | 12篇 |
2011年 | 18篇 |
2010年 | 13篇 |
2009年 | 7篇 |
2008年 | 12篇 |
2007年 | 13篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 10篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 17篇 |
1998年 | 74篇 |
1997年 | 46篇 |
1996年 | 43篇 |
1995年 | 28篇 |
1994年 | 20篇 |
1993年 | 20篇 |
1992年 | 16篇 |
1991年 | 16篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1976年 | 16篇 |
1975年 | 7篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1972年 | 9篇 |
1971年 | 4篇 |
1970年 | 2篇 |
1969年 | 4篇 |
1968年 | 2篇 |
排序方式: 共有605条查询结果,搜索用时 171 毫秒
101.
Plasma progestins, estradiol, and luteinizing hormone following prostaglandin F2 alpha injection 总被引:1,自引:0,他引:1
JR Chenault WW Thatcher PS Kalra RM Abrams CJ Wilcox 《Canadian Metallurgical Quarterly》1976,59(7):1342-1346
Dairy animals, ranging from days 8 to 13 of the estrous cycle, were fitted with indwelling jugular catheters 1 day prior to either intramuscular injection of prostaglandin F2alpha free acid (30 mg, n=4) or intrauterine deposition of prostaglandin F2alpha free acid (10 mg, n = 3). Blood samples were collected at 6, 4, 2, and 0 h prior to administration of prostaglandin F2alpha and at 1, 3, and every 2 h thereafter until ovulation. Progestins, estradiol, and luteinizing hormone in plasma were measured by radioimmunoassay. Hormonal changes and interrelationships within animals were evaluated by least squares analyses. Decreases in progestins of plasma within 24 h indicated prostaglandin F2alpha induced luteolysis in six of the seven animals. Estradiol increased linearly from time of injection to 52 h postinjection. Intervals from administration of prostaglandin to onset of estrus, peak of luteinizing hormone, and ovulation were 74.9 +/- 21, 78.8 +/- 21, and 99.5 +/- 19 h. 相似文献
102.
103.
Thirty-six lactating Holstein cows were in a 5 × 3 factorial partially balanced incomplete block design with three missing categories to study effects of different forms of cottonseed hulls and liquid supplements on milk production and composition. Roughages were regular cottonseed hulls, pelleted cottonseed hulls, pelleted cottonseed hulls with 9% fat, pelleted undelinted cottonseed hulls, and pelleted undelinted cottonseed hulls with 9% fat. Liquid supplements were 8% Masonex2 (hemicellulose extract) and 8% cane molasses. Control had no supplement. All rations were adjusted to contain 30% cottonseed hulls. Roughages with added fat gave total rations of 2.5% added fat (air dry).Least square means for daily intake of dry matter, milk yield, and fat percent were regular cottonseed hulls 21.6 kg, 20.3 kg, 3.37%; pelleted cottonseed hulls 20.3 kg, 21.4 kg, 3.06%; pelleted cottonseed hulls plus fat 20.1 kg, 21.2 kg, 2.51%; pelleted undelinted cottonseed plus fat 19.4 kg, 20.9 kg, 2.73%. Pelleted cottonseed hulls increased milk yield, decreased dry matter intake and milk fat percent, but did not affect milk fat yields. Rations with pelleted undelinted cottonseed hulls resulted in higher milk fat percent and body weight than pelleted cottonseed hulls. Added fat decreased milk fat percent and yield because of high degree of unsaturation. Liquid treatments produced no detectable effects on dry matter intake, milk yield, or fat percent. 相似文献
104.
This paper is a review of 459 outpatients treated in double-blind clinical drug trials using similar protocols which compared the clinical responses to specific serotonin reuptake inhibitors, norepinephrine reuptake inhibitors, mixed norepinephrine serotonin reuptake inhibitors, serotonin-2 antagonists and placebo. Although improvements in the total score on the Hamilton Rating Scale for Depression did not differ significantly among the groups, there were differences in the profile of response based on analysis of the items of the scale. The most striking difference was the significantly more rapid and effective improvement in depressed mood and the lessening of suicidal ideation among the patients treated with specific serotonin reuptake inhibitors. 相似文献
105.
Because changes in intracellular Ca2+ affect progression through the mitotic cell cycle, we investigated the role of Ca2+-binding proteins in regulating cell cycle progression. Evidence was found demonstrating that the activation of Ca2+/calmodulin-dependent protein kinase (CaM kinase) inhibits cell cycle progression in small cell lung carcinoma (SCLC) cells. We also demonstrated that SCLC cells express both CaM kinase type II (CaMKII) and CaM kinase type IV (CaMKIV). Five independent SCLC cell lines expressed proteins reactive with antibody to the CaMKII beta subunit, but none expressed detectable proteins reactive with antibody to the CaMKII alpha subunit. All SCLC cell lines tested expressed both the alpha and beta isoforms of CaMKIV. Immunoprecipitation of CaMKII from SCLC cells yielded multiple proteins that autophosphorylated in the presence of Ca2+ / calmodulin. Autophosphorylation was inhibited by the CaMKII(281-302) peptide, which corresponds to the CaMKII autoinhibitory domain, and by 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4- phenylpiperazine (KN-62), a specific CaM kinase antagonist. Influx of Ca2+ through voltage-gated Ca2+ channels stimulated phosphorylation of CaMKII in SCLC cells, and this was inhibited by KN-62. Incubation of SCLC cells of KN-62 potently inhibited DNA synthesis, and slowed progression through S phase. Similar anti-proliferative effects of KN-62 occurred in SK-N-SH human neuroblastoma cells, which express both CaMKII and CaMKIV, and in K562 human chronic myelogenous leukemia cells, which express CaMKII but not CaMKIV. The expression of both CaMKII and CaMKIV by SCLC cells, and the sensitivity of these cells to the anti-proliferative effects of KN-62, suggest a role for CaM kinase in regulating SCLC proliferation. 相似文献
106.
YD Fragoso PL da Fonseca MB Fortinguerra L Cominato Gde O Matte CM Oliveira 《Canadian Metallurgical Quarterly》1998,116(2):1650-1653
OBJECTIVES: Primary headaches are often seen by Clinicians on duty at Emergency Services. We have investigated the treatment of such patients by 43 medical doctors who have been working at Emergency Services in the city of Santos and surrounding towns for many years. RESULTS: We confirmed the high prevalence of primary headaches in Emergency Services. There seem to be diagnosis difficulties concerning differentiating attacks of migraine and tension type headache. We also observed that IV dipirone was the most frequently prescribed treatment for patients with primary headaches in this study. There is no protocol in the literature which recommends IV dipirone for the treatment of migraine attacks or other primary headaches. CONCLUSION: It would be advisable to perform controlled double blind studies in order to verify the advantages of IV dipirone in the treatment of intense attacks primary headaches. We concluded that headache management recycling programs could be of interest for doctors who regularly work at Emergency Services. 相似文献
107.
108.
Vital statistics were evaluated for artificial insemination sires leaving service during 1939 through 1974. Data consisted of 11,704 sires of six breeds. The major cause for leaving service was reproductive failure at a frequency of 32.5%; next ranked was undesirable characteristics of offspring with a frequency of 20.7%. Overall culling rate for low yields of daughters was 14.8%, but after 1965 this cause accounted for about 30%. Mean life span was 3.4 yr with small differences among years. Breed differences were detected for service life and causes for leaving service. Modifications of classic life table techniques are needed to reflect entry of sires into service at various ages and evaluation of vital statistics subsequent to 1974. 相似文献
109.
James D. McCambridge Myles A. Steiner Blair L. Unger Keith A. Emery Eric L. Christensen Mark W. Wanlass Allen L. Gray Laszlo Takacs Roger Buelow Timothy A. McCollum James W. Ashmead Greg R. Schmidt Alex W. Haas John R. Wilcox James Van Meter Jeffery L. Gray Duncan T. Moore Allen M. Barnett Richard J. Schwartz 《Progress in Photovoltaics: Research and Applications》2011,19(3):352-360
We have designed, fabricated, and tested a small, integrated photovoltaic module comprised of two separately‐contacted, high efficiency, multijunction solar cells and non‐imaging optics that both concentrate and spectrally split the incoming light. This hybrid design allows us to individually optimize the tandem cells and optical elements. The system has a measured module efficiency, including optical and packaging losses but not power combination losses, of 38.5 ± 1.9% under the AM1.5 direct terrestrial spectrum. The internal optics concentrate the light by a factor of approximately 20. We find excellent agreement between the modeled and measured performance. This is the highest confirmed conversion efficiency demonstrated for a photovoltaic module. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
110.
The biomechanics of vertebroplasty: a review 总被引:2,自引:0,他引:2
Wilcox RK 《Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine》2004,218(1):1-10
Percutaneous vertebroplasty and kyphoplasty are being used extensively in the United States for the treatment of osteoporotic vertebral compression fractures. Although short-term clinical outcomes appear favourable, long-term data are not yet available and it is becoming increasingly important to understand how the underlying biomechanics of the spine are altered by the procedure. In vitro experimental studies have investigated the effect of cement augmentation on individual vertebra and short spinal segments. For individual vertebra, vertebroplasty appears to increase or return strength to the prefracture level, whereas the stiffness is not always restored. However for multiple-vertebra segments, the strength of the unit as a whole appears to decrease, with failure occurring in the non-augmented vertebrae. Both finite element (FE) and experimental studies have shown that the volume of cement injected affects the restoration of strength and stiffness. The type of cement appears to have less of an effect. Although biomechanical studies of the vertebroplasty process have indicated that the procedure has the potential to restore vertebral strength and stiffness, further work is necessary to understand fully the effects of the augmentation process on the surrounding structures if the treatment is to be fully optimized. This paper is a review of the biomechanical data available on vertebroplasty. 相似文献