全文获取类型
收费全文 | 2562篇 |
免费 | 42篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 14篇 |
综合类 | 16篇 |
化学工业 | 42篇 |
金属工艺 | 19篇 |
机械仪表 | 27篇 |
建筑科学 | 21篇 |
矿业工程 | 6篇 |
能源动力 | 5篇 |
轻工业 | 23篇 |
水利工程 | 8篇 |
石油天然气 | 4篇 |
无线电 | 90篇 |
一般工业技术 | 100篇 |
冶金工业 | 2196篇 |
原子能技术 | 1篇 |
自动化技术 | 40篇 |
出版年
2023年 | 4篇 |
2022年 | 5篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 9篇 |
2017年 | 4篇 |
2015年 | 8篇 |
2014年 | 10篇 |
2013年 | 14篇 |
2012年 | 15篇 |
2011年 | 26篇 |
2010年 | 18篇 |
2009年 | 26篇 |
2008年 | 22篇 |
2007年 | 25篇 |
2006年 | 18篇 |
2005年 | 23篇 |
2004年 | 14篇 |
2003年 | 26篇 |
2002年 | 17篇 |
2001年 | 13篇 |
2000年 | 4篇 |
1999年 | 92篇 |
1998年 | 674篇 |
1997年 | 385篇 |
1996年 | 250篇 |
1995年 | 142篇 |
1994年 | 132篇 |
1993年 | 151篇 |
1992年 | 22篇 |
1991年 | 19篇 |
1990年 | 14篇 |
1989年 | 20篇 |
1988年 | 32篇 |
1987年 | 27篇 |
1986年 | 17篇 |
1985年 | 17篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 10篇 |
1981年 | 16篇 |
1980年 | 24篇 |
1979年 | 7篇 |
1978年 | 11篇 |
1977年 | 65篇 |
1976年 | 124篇 |
1975年 | 10篇 |
1974年 | 3篇 |
1966年 | 3篇 |
排序方式: 共有2612条查询结果,搜索用时 10 毫秒
51.
A Chander KR Dhariwal R Viswanathan TA Venkitasubramanian 《Canadian Metallurgical Quarterly》1977,34(6):341-347
Fatty acid metabolism was investigated in adult male albino rats exposed to hypobaric hypoxia at 25,000 ft simulated altitude for 6 h at 32 degrees C. Oxidation and esterification of palmitic acid-1-14C and de novo lipogenesis from acetate-1-14C were studied. Palmitic acid-1-14C oxidation in liver slices was normal while acetoacetate formation was increased. In vivo esterification of palmitic acid-1-14C to form triglycerides was increased while formation of phosphatidylcholine and phosphatidylethanolamine was observed to decrease. Decreased incorporation into plasma phosphatidylcholine with unaltered total activity in plasma triglycerides was observed. The incorporation of acetate-1-14C was observed to remain unaltered in triglycerides and phospholipids of liver with a similar pattern in the plasma indicating unaltered de novo lipogenesis. There appears to be increased esterification of fatty acids with probably impaired release of triglycerides into plasma while fatty acid biosynthesis remains unaffected. 相似文献
52.
TW Langfitt WD Obrist TA Gennarelli MJ O'Connor CA Weeme 《Canadian Metallurgical Quarterly》1977,186(4):411-414
In order to determine the relationship of cerebral blood flow (CBF) to the clinical outcome of head injury, serial determinations of CBF were performed by the intravenous Xenon technique in 24 patients. The patients were of mixed injury severity and were classified into four groups depending on the neurological exam at the time of each CBF study. All eight patients who were lethargic on admission demonstrated increases in their minimally depressed CBF as they improved to normal status. Eleven patients in deep stupor or coma ultimately recovered. Ten of these patients initially had moderate to profound decreases in CBF which improved as recovery occurred. The single exception was an adolescent whose initial CBF was high but became normal at recovery. Five comatose patients died. In four of these, already depressed CBF fell even lower, while one adolescent with initially increased CBF developed very low CBF preterminally. The data presented in this report demonstrated a good correlation between CBF and clinical outcome. In every one of the adult survivors, depressed CBF increased as the patient recovered to normal status. All adults who died showed a deterioration of CBF as the neurological status worsened. The only exceptions were two adolescents who initially showed high CBF values. In the adolescent who died, CBF dropped to low levels while in the survivor a normal CBF was achieved. Thus in adults a traumatic brain injury was associated with depressed CBF which increased with recovery or decreased further with deterioration while the reaction to injury was quite different in the younger brain. 相似文献
53.
Morphology of atypical myocardial infarctions and their morphogenesis were studied in 120 cases. The importance of atherosclerosis as the background process, the secondary development of coronary thrombosis and the leading role of metabolic factors (hypoxy, acidosis, etc) in the origin of atypical myocardial infarctions were established. 相似文献
54.
W Pawlik LL Tague BL Tepperman TA Miller ED Jacobson 《Canadian Metallurgical Quarterly》1977,233(3):E219-E224
Studies were conducted in anesthetized dogs to determine whether the mesenteric vasodilator response to histamine is mediated by H1 receptors alone or whether H2 receptors are also involved in the response. Evidence favoring a role for both receptors included: 1) the vasodilator response to histamine was inhibited by either the H1-receptor antagonist, tripelennamine, or the H2-receptor antagonist, metiamide; 2) both the H1 agonist, 2-methylhistamine, and the H2 agonist, 4-methylhistamine, induced dilator responses in the mesenteric circulation; and 3) two temporal patterns of vasodilation could be distinguished, namely a transient spike and subsequent fade of blood flow (seen with either the H1 agonist or with histamine after H2-receptor blockade) and a sustained and stable increase in flow (seen with either the H2 agonist or with histamine after H1 blockade). Metiamide appeared to be a potent inhibitor of the mesenteric vasodilator response to histamine at least equal to tripelennamine. 相似文献
55.
Two unusual anaerobic vibrio-like organisms were recovered from blood cultures of two patients. One isolate was identified as Desulfovibrio desulfuricans. It appeared to be the cause of a 24-h episode of fever, chills, and profuse perspiration. This is apparently the first documented report of human infection due to this organism. The second isolate was a Succinivibrio species. It has rarely been described as a cause of bacteremia. The clinical significance of the organism remains unclear. 相似文献
56.
57.
The effect of morphine microinjection (5 microgram/0.5 microliter) and focal electrical stimulation on the animal's response to radiant heat and noxious pinch was studied concurrently at 117 brain loci extending from the medial thalamus caudally to the periaqueductal gray area (PAG). Three populations of brain sites were discernible based on their responsiveness to focal electrical stimulation and morphine microinjection in the production of antinociception: (a) sites which support stimulation-produced analgesia (SPA, n = 24), (b) sites which were sensitive to the direct application of morphine (n = 8), (c) sites responsive to both manipulations (n = 8). With a few exceptions, all morphine sensitive sites were located within the anatomical boundaries of the PAG while sites supporting SPA were located not only within the PAG but also in the brain regions peripheral to this structure. Sites responsive to both manipulations were generally distributed throughout thf lateral aspect of the posteroventral PAG. Stimulation strength-effect curves for sites subserving SPA were also obtained. No differences were discovered between curves obtained from morphine-sensitive and -insensitive brain loci. 相似文献
58.
VS Alekseeva TA Karaseva VL Na?din NA Shtamberg 《Canadian Metallurgical Quarterly》1977,77(9):1329-1333
The report contains data concerning occupational and social rehabilitation of 46 patients operated on for aneurysma of the anterior communicative artery. It was established that the occupational prognosis depends upon the severity of the hemmorhage, character of surgical operation. Of significance are the conditions of work, time after the surgical operation. The authors mark that in 2/3 of the operated on patients the working capacity is being restored. A spontaneous restoration of diaturbed functions is slow and is not always sufficient. With this purpose it is expedient to repeat courses of a general tonic and special rehabilitative therapy. A favourable factor in the readaptation of patients is their early engagement in working activities. The authors give their recommendations for medical labour expert testimony for this category of patients. 相似文献
59.
为探明黄河内蒙古段沉积物中砷含量及形态分布特征,采集黄河内蒙古段干流柱状沉积物,采用HNO4-H2SO4-HCl O4法消解沉积物样品,提取沉积物中吸附型砷(A-As)、铝型砷(Al-As)、铁型砷(Fe-As)、钙型砷(CaAs)、包蔽型砷(O-As)5种形态砷,并采用氢化物发生原子荧光分光光度法测定砷含量。结果表明:黄河内蒙古段干流柱状沉积物中砷含量为7.123~16.661 mg/kg,平均为9.292 mg/kg;从整体上看,左岸沉积物砷含量高于右岸,随深度增加砷含量呈下降趋势,从上游至下游砷含量在黑柳子段出现高值;黄河内蒙古段沉积物中砷以Ca-As为主,O-As次之;随着深度的增加,总体上,Ca-As含量略有升高,A-As和O-As含量有所下降,Al-As和Fe-As含量基本不变。 相似文献
60.