全文获取类型
收费全文 | 222篇 |
免费 | 7篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 38篇 |
化学工业 | 4篇 |
金属工艺 | 5篇 |
机械仪表 | 4篇 |
建筑科学 | 2篇 |
矿业工程 | 1篇 |
轻工业 | 12篇 |
无线电 | 6篇 |
一般工业技术 | 2篇 |
冶金工业 | 153篇 |
原子能技术 | 2篇 |
自动化技术 | 7篇 |
出版年
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2013年 | 9篇 |
2012年 | 11篇 |
2011年 | 7篇 |
2010年 | 2篇 |
2009年 | 6篇 |
2008年 | 1篇 |
2007年 | 3篇 |
2005年 | 3篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 12篇 |
1998年 | 46篇 |
1997年 | 27篇 |
1996年 | 25篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 10篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1982年 | 1篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 4篇 |
1976年 | 18篇 |
1958年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有236条查询结果,搜索用时 15 毫秒
31.
There is an early period of puberty in boys at the age of 10 to 13, accompanied by an increase in the level of follicle stimulating hormone and a low secretion of luteinizing hormone and testosterone, with no secondary sexual signs. The beginning of an increase in the luteinizing hormone and testosterone concentration in boys coincides with the development of secondary sexual signs. The stabilization of the level of luteinizing hormone takes place in boys already at the 2nd degree of the sexual development. The secretion of luteinizing hormone at this point corresponds already to the normal level in adult men. The level of testosterone in the blood continues to increase and does not reach its definitive level until after the age of 17, or at the 5th degree of sexual development. Like in boys, the increase of the follicle stimulating hormone in girls precedes the increase of the luteinizing hormone secretion. The beginning of the increase in the follicle stimulating hormone coincides with an increase in the level of estrogens and testosterone in the blood, and with the appearance of secondary signs of sexual maturation. The increase of the luteinizing hormone secretion takes place later in girls than in boys and is accompanied by a new and significant increase in the level of estrogens in the blood. At the 2nd degree of sexual development, the level of testosterone in the blood of girls is substantially higher than at the other stages. 相似文献
32.
33.
34.
NA Brazhenko ZI Kostina IuE Godes LL Krokhaleva ON Brazhenko OI Tsareva NM Balashova 《Canadian Metallurgical Quarterly》1998,114(5):48-51
AIM: The study of the detection rate and potential pathogenetic significance of antibodies to low density oxidated lipoprotein (LDOL) in patients who had ischemic cerebral circulation disorder (ICCD) at young age. MATERIALS AND METHODS: The examination (enzyme immunoassay, general and neurological investigations, laboratory and instrumental tests) covered 148 patients who survived ICCD at young age (mean age 37.2 years). RESULTS: 48 of 108 (44%) patients had LDOL antibodies. Antibodies to cardiolipin, lupus anticoagulant were recorded in 33 (31%) patients. LDOL antibodies were higher and occurred more frequently in patients with Sneddon's syndrome (35% of patients, mean LDOL antibodies-44 units) and primary antiphospholipid syndrome (17% of patients, 45 units) than in atherosclerotic affection of the major head arteries (4%, 29 units) or occlusion of cerebral arteries of unclear genesis (8% of patients, 29 units). CONCLUSION: ICCD were not related to fast development of cerebral atherosclerosis or periaortitis due to production of LDOL antibodies as no relationships were found between their rise and atherosclerotic lesions of cerebral major arteries or periaortitis as shown by ultrasonic dopplerography or cerebral angiography. Feasibility of LDOL antibodies participation in the coagulation cascade and induction of hypercoagulatory condition causing ICCD needs special investigation. 相似文献
35.
36.
The activated tyrosine kinase oncoprotein BCR-ABL is responsible for pathogenesis of Philadelphia chromosome-positive human leukemias. Because BCR carries a GAP (GTPase-activating protein) activity toward cytoskeleton-related small GTP-binding proteins, we utilized a neuronal PC12 cell system to test morphogenic potentials of BCR-ABL or BCR. We report here unique morphological phenotypes of PC12 cells expressing either BCR-ABL or a BCR mutant which lacks the SH2-binding domain (BCR Delta162-413). Although MAP kinase was not activated in PC12 cells expressing BCR-ABL, they showed incomplete neurite extensions even in the absence of the nerve growth factor (NGF). Overproduction of BCR Delta162-413 in PC12 cells, on the other hand, induced cell rounding in the absence of NGF. Interestingly, those cells could hardly make terminal differentiation in the presence of NGF and continued to grow without changing their round shape, although NGF receptor as well as MAP kinase appeared to be activated. Interestingly, the botulinum C3 toxin induced neurite-like structures in PC12 cells overexpressing BCR Delta162-413 without NGF. 相似文献
37.
A procedure is described for extracting doxepin, a tricyclic antidepressant, from plasma and subsequently measuring its concentration by GLC. The developed technique permits the resolution and quantitative determination of the cis- and trans-isomers of doxepin as well as its desmethyl metabolite. The method allows precise, reliable measurement of the drug and one of its metabolities in concentrations as low as 10 ng/ml of plasma. 相似文献
38.
RESEARCH SECTION ON PROCEEDING SOLID FUEL PEKING INSTITUTE OF PETROLEUM TECHNOLOGY 《化工学报》1958,9(2):95-101
试验了国产的各种硬蜡及软蜡,确定了它们的氧化可能性。提出了可供工业上应用的加速氧化反应的二个方法:改善加入催化剂的方法及在泡沫状态下进行氧化。 对於简化分离氧化蜡亦提出了新方案。 文中还叙述了在氧化初期催化剂的作用,对工艺过程的控制有一定的帮助。 相似文献
39.
40.
OA Kovalev AI Gurbanova SK Sheremetevskaia ON Nepochatov 《Canadian Metallurgical Quarterly》1976,82(9):1045-1047
The authors describe relative changes in the blood filling of 46 vascular areas of the body in rats after a moderate and severe blood loss. Moderate blood loss caused redistribution of the blood from the skin of the chest and from the skin of the posterior limbs, the majority of the abdominal and pelvis minor organs, muscular and bone tissues of the abdomen, pelvis minor and extremities into the brain, heart, lungs, kidneys, stomach and into the muscles of the head and neck. In severe blood loss the changes were analogous, but the blood content in the kidneys and the stomach decreased, and there was also a relative elevation of the blood in the muscles and bones of the chest. The intensity of the redistributive reaction in severe blood loss was less than in moderate blood loss. 相似文献