全文获取类型
收费全文 | 4325篇 |
免费 | 20篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 79篇 |
金属工艺 | 13篇 |
机械仪表 | 8篇 |
建筑科学 | 16篇 |
能源动力 | 43篇 |
轻工业 | 76篇 |
水利工程 | 1篇 |
石油天然气 | 3篇 |
无线电 | 33篇 |
一般工业技术 | 64篇 |
冶金工业 | 3948篇 |
原子能技术 | 5篇 |
自动化技术 | 51篇 |
出版年
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 11篇 |
2018年 | 9篇 |
2017年 | 7篇 |
2016年 | 11篇 |
2015年 | 15篇 |
2014年 | 20篇 |
2013年 | 30篇 |
2012年 | 25篇 |
2011年 | 28篇 |
2010年 | 40篇 |
2009年 | 30篇 |
2008年 | 30篇 |
2007年 | 15篇 |
2006年 | 13篇 |
2005年 | 14篇 |
2004年 | 9篇 |
2003年 | 15篇 |
2002年 | 11篇 |
2001年 | 10篇 |
2000年 | 7篇 |
1999年 | 115篇 |
1998年 | 1183篇 |
1997年 | 714篇 |
1996年 | 458篇 |
1995年 | 225篇 |
1994年 | 232篇 |
1993年 | 219篇 |
1992年 | 20篇 |
1991年 | 50篇 |
1990年 | 40篇 |
1989年 | 44篇 |
1988年 | 35篇 |
1987年 | 44篇 |
1986年 | 54篇 |
1985年 | 34篇 |
1983年 | 14篇 |
1982年 | 17篇 |
1981年 | 27篇 |
1980年 | 52篇 |
1979年 | 3篇 |
1978年 | 10篇 |
1977年 | 110篇 |
1976年 | 261篇 |
1975年 | 8篇 |
1964年 | 1篇 |
1955年 | 5篇 |
1954年 | 2篇 |
排序方式: 共有4345条查询结果,搜索用时 15 毫秒
41.
42.
43.
War is a complex social situation due to the interplay of multiple factors. Economical and political ones are of utmost importance, but human attitudes and motivations must be also taken into account. Being desirable to modify human transactions in such a way that they do not interfere with the basic right of everyone to a condition of physical and mental well-being, war must be abolished. The author contends that an understanding of behaviour through Psychology can be helpful in that aim. Aggression is considered the principal psychological cause of war. It is worth while to differentiate between aggression as an instrument for attaining a special end, and as pure hostility. Only in the first form, it is held here, does it play an important role in war. Psychogists must deal also with a wide range of states of mind that can be "served" by aggression: feelings of inferiority or insecurity, fear, greed, projections, compensations, rationalizations, etc. Scientific approach is not the only one Physiology brings to war prevention. It is equally important the wide dissemination of its conclusions among the general public. Information on the dynamics that prompt people to decide war would make it easier to control. This applies not only to political or military leaders, but also to civil populations. Concerning those two possible contributions of psychologists, scientific and educative, it is suggested the extensive use of psychodramatic techniques. Their richness lie in the lifelike experiences they convey to the participants, and particular aptitude to promote changes of attitudes. Investigation and information on the psychological processes related to war should be undertaken by international organizations of social scientists, acting simultaneously in several countries. Some of the initial steps they could further: 1) that prevention of war be a current subject matter in psychological courses; 2) that the World Health Organization take interest in this subject; 3) that psychologists participate in international political and economical bodies in order to clarify the psychological factors leading to war. 相似文献
44.
45.
JF Godeau YG Beuzard J Cacheleux CP Brizard A Gibaud J Rosa 《Canadian Metallurgical Quarterly》1976,251(14):4346-4354
The unstable hemoglobin (Hb) Saint Etienne (alpha2beta295F8 His replaced by G1n) (betaSE) was found in the red blood cells of an 8-year-old boy. The composition of this hemoglobin was 26% Saint Etienne, 52% A, 3% A2 and 19% HbF. Studies of hemoglobin synthesis indicate: a) a balanced synthesis of alpha and non-alpha chains (alpha=betaA + betaSE + gamma), b) an increased pool of free alpha hemoglobin chains, and c) a rapid exchange of alpha chains between this pool and HbSE. The alpha chain pool resulted from the dissociation of HbSE and the greater instability of betaSE chains than alpha chains upon heating. Hemoglobin F is of the fetal type and is heterogeneously distributed among the red cells. Furthermore, two populations of red blood cells could be separated according to their i antigen content. Analysis of the hemoglobins revealed a heterogeneous distribution. Thus, F hemoglobin was preferentially associated with cells having low i antigen level, while Saint Etienne hemoglobin was increased in cells having a high i antigen level. HbF and HbSE were not present in the parents of the propositus. Study of the genetic markers confirmed the filiation. The parents were normal upon clinical and hematological examination; they exhibited a normal pattern and synthesis of hemoglobin. The Hb Saint Etienne case is compared with Hb Istanbul, which in spite of the same amino acid substitution is not associated with increased HbF level. 相似文献
46.
47.
48.
E. Anastasaki C. Kanakis C. Pappas L. Maggi C. P. del Campo M. Carmona G. L. Alonso M. G. Polissiou 《European Food Research and Technology》2010,230(4):571-577
Mid-infrared spectroscopy combined with multivariate analysis has been applied for the discrimination of 250 saffron samples
from Greece (40 samples), Iran (87 samples), Italy (60 samples) and Spain (63 samples). The infrared spectra of saffron filament
samples and their organic extracts were recorded. Principal component analysis was applied to different spectral regions.
Then the principal components were used as variables in discriminant analysis. The best discriminatory approach was achieved
in the spectral region 2000–700 cm−1. The spectral region responsible for the differentiation of Italian samples is in the region of carbonyl group around 1746 cm−1. The spectral region at around 1600 cm−1 and the band at 1670 cm−1 are responsible for the differentiation of samples from the remaining countries. From the original grouped cases, 93.6% were
correctly classified. The correct classification rates for saffron samples from Greece, Iran, Italy and Spain were 90.0, 89.5,
96.7 and 98.4%, respectively. The combination of infrared spectroscopic technique with multivariate analysis is a rapid and
ambient method to discriminate saffron samples in terms of geographical origin. 相似文献
49.
Serra X Gil M Gispert M Guerrero L Oliver MA Sañudo C Campo MM Panea B Olleta JL Quintanilla R Piedrafita J 《Meat science》2004,66(2):425-436
Seventy-four young bulls of the Bruna dels Pirineus beef cattle breed were reared in a typical production system and slaughtered at an average age of 381 days and live weight of 541 kg. The animals were evaluated for productive traits, carcass quality, meat quality, eating quality and biochemical characteristics of m. longissimus thoracis (LT). Biochemical measurements included intramuscular fat (IMF) and collagen proportion, haem pigment concentration, lactate dehydrogenase and isocitrate dehydrogenase activities and type I (MHC I) fibre percentage determined by ELISA. Bruna dels Pirineus bulls achieved high growth rates during the fattening period (1.63 kg/day) and showed good carcass quality, with a high dressing-out proportion (607 g/kg, hot carcass), a good conformation score (U; EUROP) and a moderate fatness score (3;1-5). Carcass composition was estimated from the sixth rib joint dissection (682 g/kg lean proportion, 127 g/kg total dissectable fat and 163 g/kg bone). IMF (24.3 g/kg) and MHC I (27.9%) showed high variabilities (CV>30%). Sensory analysis of LT included beef and livery odour and flavour intensity, and overall tenderness and juiciness assessment of loin samples (14-day ageing). Beef odour and flavour were slightly positively correlated with IMF and carcass fatness score (P<0.05). Fatness, MHC I, insoluble collagen and cooking losses tended to affect the livery flavour intensity positively. This variable was significantly higher in meat from bulls of lower carcass quality (i.e. lower conformation score, lower lean proportion; P<0.05) and higher type I fibre percentage. Loin overall tenderness and juiciness were not affected by the biochemical traits studied, however, they were negatively affected by cooking loss (P<0.05). 相似文献