全文获取类型
收费全文 | 5895篇 |
免费 | 8篇 |
国内免费 | 1篇 |
专业分类
综合类 | 1篇 |
化学工业 | 37篇 |
金属工艺 | 3篇 |
机械仪表 | 2篇 |
建筑科学 | 2篇 |
矿业工程 | 2篇 |
能源动力 | 2篇 |
轻工业 | 20篇 |
无线电 | 4篇 |
一般工业技术 | 13篇 |
冶金工业 | 5809篇 |
原子能技术 | 1篇 |
自动化技术 | 8篇 |
出版年
2022年 | 3篇 |
2020年 | 4篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2014年 | 5篇 |
2013年 | 4篇 |
2012年 | 4篇 |
2011年 | 4篇 |
2010年 | 5篇 |
2009年 | 1篇 |
2008年 | 2篇 |
2007年 | 6篇 |
2006年 | 3篇 |
2005年 | 4篇 |
2004年 | 6篇 |
2003年 | 12篇 |
2002年 | 2篇 |
2000年 | 3篇 |
1999年 | 184篇 |
1998年 | 1916篇 |
1997年 | 1096篇 |
1996年 | 701篇 |
1995年 | 377篇 |
1994年 | 275篇 |
1993年 | 357篇 |
1992年 | 42篇 |
1991年 | 42篇 |
1990年 | 53篇 |
1989年 | 44篇 |
1988年 | 36篇 |
1987年 | 38篇 |
1986年 | 37篇 |
1985年 | 44篇 |
1984年 | 1篇 |
1983年 | 9篇 |
1982年 | 19篇 |
1981年 | 37篇 |
1980年 | 52篇 |
1979年 | 2篇 |
1978年 | 15篇 |
1977年 | 129篇 |
1976年 | 291篇 |
1975年 | 13篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1965年 | 1篇 |
1963年 | 1篇 |
1955年 | 4篇 |
排序方式: 共有5904条查询结果,搜索用时 11 毫秒
21.
22.
23.
24.
Cognitive performance in conversion hysteria 总被引:1,自引:0,他引:1
In order to test some neurobiologically based assumptions pertaining to attention and memory dysfunction in conversion hysteria, a series of tasks was given to 17 hospitalized patients with hysterical conversion reaction and to a control group of nonpsychotic patients under conditions of nonstress and stress. The results indicated significant differences in performance between hysteria and control subjects. The former group, in comparison to controls, had heightened suggestibility, greater field dependency, and greater impairment of recent memory and vigilance-attention. A discriminant analysis indicated the feasibility of using such tests as objective diagnostic criteria for hysteria. 相似文献
25.
Serum and urinary myo-inositol and urinary glucose were estimated by means of gas-liquid chromatography in 54 patients with glomerulonephritis with and without renal failure. myo-Inositol clearance was calculated and an index was formulated which reflected changes in glomerular filtration, tubular reabsorption and catabolism of myo-inositol by the kidney. Serum and urinary myo-inositol levels were increased in glomerulonephritis with a close correlation to the degree of renal failure. In advanced forms of glomerulonephritis, glomerular filtration, tubular reabsorption and catabolism of myo-inositol were shown to be markedly deranged. Evidence obtained showed further that a derangement of tubular reabsorption and catabolism of myo-inositol also accompany milder forms of glomerulonephritis without decreased glomerular filtration. The myo-inositol index value, especially, was increased in patients with signs of disease activity as indicated by a histological examination of the kidney tissue. The index can also be regarded as a highly sensitive test of renal failure. Low grade glucosuria was shown to be frequently associated with glomerulonephritis with renal failure. Evidence was produced which suggested that the tubular reabsorption of myo-inositol was deranged earlier than glucose reabsorption in glomerulonephritis, although they may share a common step in the reabsorption process. The data suggest that the estimation of serum and urinary myo-inositol has advantages in the evaluation of kidney function. 相似文献
26.
A theoretical model is developed to predict pressure changes and velocity profiles within the foetal lung during its sporadic bursts of activity. Because of the small volume flow rates and relatively high frequencies, the linearised, unidirectional Navier-Stokes equations are used to calculate these values. About 70% of the pressure drop occurs in the first four generations and is an order of magnitude higher than the equivalent Poiseuille pressure drop. Velocity profiles, pressure falls within each generation together with the total pressure drop at different times during the cycle are illustrated. 相似文献
27.
A 7-year-old girl twice developed severe hypernatremia (serum sodium values up to 194 mEq/l) without obvious cause. The ability of her kidneys to conserve water was normal, and increasing her plasma osmolality stimulated an appropriate ADH response. Unable to excrete a water load, her kidneys continued to conserve water even with a serum sodium concentration of 133 mEq/l. She was never thirsty and did not ingest sufficient fluid by choice. Although there was no demonstrable anatomic lesion, we postulate a localized defect of her thirst center. This may have modified release of ADH and resulted in an inability to dilute the urine by interrupting a pathway that could exist from the thirst center to the supraoptic nuclei. A therapeutic regimen based on these studies has prevented further hypernatremia. 相似文献
28.
Binary mixtures of weak and strong UV-absorbing alkaloids were analyzed by a charge-transfer spectrophotometric method, utilizing iodine in ethylene dichloride as the acceptor. In the uncomplexed form, the strong absorbing alkaloid (papaverine, quinine, ergotamine, or reserpine) was measured at a wavelength where there was no interference from weak absorbers (at 335, 332, 315, or 300 nm, respectively). The weak absorbing alkaloid (ephedrine, codeine, atropine, or homatropine methylbromide) was determined by computing its contribution to the total charge-transfer band at 295 nm where absorbance was linearly additive for mixtures. The greater increase in the original epsilon-values of the weak absorbers upon complexation with iodine relative to the corresponding increase in the epsilon-values of the strong absorbers led to good recoveries even at the low dose ratios of the weakly absorbing, and often more potent, alkaloids. 相似文献
29.
Two cases of juvenile gastrointestinal polyposis are described and the literature is reviewed. Despite the benign nature of the individual polyps, the disease has a poor prognosis. Of 13 reported patients, 4 had macrocephaly, and one of the authors' 2 patients had large peripheral intracranial cysts. This appears to be the first reported documentation of the etiology of macrocephaly associated with juvenile polyposis. Major clinical problems are related to severe loss of blood and protein from the gastrointestinal tract. 相似文献
30.
AM Mingers 《Canadian Metallurgical Quarterly》1976,123(3):199-213
Factor VIII exchange test experiments with hemophilia A plasmas were performed to find out how the results were affected by submitting plasmas and plasma mixtures to different incubation periods at 37 degrees C, heat precipitation, and ether extraction. The experiments led to the following results: 1. In plasma mixtures, frequently higher factor VIII activities are found than can be expected from the single activities of the used plasmas. Activity increases are factor-specific. 2. The component to be activated is in the hemophilic plasma; the activity-increasing agent is in the normal plasma. These results lead to the hypothesis that hemophilia A patients have sufficient quantities of inactive factor VIII, but it stays inactive for lack of the necessary activator. In normal plasma the activator is in balance or surplus to the inactive factor. By adding normal plasma, thus supplying free activator, the inactive factor VIII of hemophilia A plasma can, under suitable conditions, be developed into active factor VIII. 相似文献