全文获取类型
收费全文 | 3548篇 |
免费 | 8篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 2篇 |
综合类 | 3篇 |
化学工业 | 26篇 |
金属工艺 | 3篇 |
机械仪表 | 2篇 |
建筑科学 | 10篇 |
矿业工程 | 1篇 |
能源动力 | 3篇 |
轻工业 | 12篇 |
石油天然气 | 1篇 |
武器工业 | 2篇 |
无线电 | 15篇 |
一般工业技术 | 9篇 |
冶金工业 | 3440篇 |
自动化技术 | 28篇 |
出版年
2022年 | 2篇 |
2020年 | 1篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2014年 | 2篇 |
2013年 | 6篇 |
2012年 | 1篇 |
2011年 | 32篇 |
2010年 | 5篇 |
2009年 | 2篇 |
2008年 | 3篇 |
2007年 | 2篇 |
2006年 | 4篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 9篇 |
2002年 | 6篇 |
2001年 | 2篇 |
2000年 | 6篇 |
1999年 | 122篇 |
1998年 | 1127篇 |
1997年 | 657篇 |
1996年 | 392篇 |
1995年 | 198篇 |
1994年 | 179篇 |
1993年 | 231篇 |
1992年 | 14篇 |
1991年 | 28篇 |
1990年 | 28篇 |
1989年 | 42篇 |
1988年 | 36篇 |
1987年 | 33篇 |
1986年 | 18篇 |
1985年 | 25篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1982年 | 22篇 |
1981年 | 15篇 |
1980年 | 27篇 |
1979年 | 3篇 |
1978年 | 14篇 |
1977年 | 78篇 |
1976年 | 141篇 |
1975年 | 5篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1955年 | 3篇 |
1954年 | 1篇 |
排序方式: 共有3557条查询结果,搜索用时 15 毫秒
21.
The effects of bilateral microinjections of mu-opioid receptor agonist DAMGO (0.00, 0.01, 0.1, or 1.0 microgram/side) were tested in rats for 120 min in activity monitors. The horizontal movement, rearing, and stereotypy times in seconds were measured during 12 consecutive 10-min time blocks. DAMGO (0.01, 0.1, and 1.0 microgram) resulted in biphasic effects, inhibition followed by activation for each of the three measures. These data replicate the behavioral effects of ICV DAMGO except that the duration of the behavioral effects were longer with Acb injections. 相似文献
22.
K Papadakis FI Luks ME De Paepe GJ Piasecki CW Wesselhoeft 《Canadian Metallurgical Quarterly》1997,32(2):347-351
We investigated cell proliferation and cell death in the olfactory epithelium (OE) of mice from birth to maturity using bromodeoxyuridine and terminal deoxynucleotidyl transferase nick end labeling. We show that cell death events and proliferative activity diminish concomitantly with age in the OE. Thus, the age-dependent and coordinate diminution in cell proliferative activity and cell death events may serve to maintain the thickness of the OE as mice mature and age. 相似文献
23.
ME Goldberg BW Lex NK Mello JH Mendelson TA Bower 《Canadian Metallurgical Quarterly》1996,66(2):228-238
Research on achievement goal orientation in sport has relied primarily on traditional statistical methodology to examine group mean differences. Unfortunately, examination of the measurement model is generally ignored prior to means testing. This study reports an application of structural equation modeling (SEM) in testing measurement invariance and latent mean structure of the Task and Ego Orientation in Sport Questionnaire (TEOSQ; Duda & Nicholls, 1989) using male and female college students. A confirmatory factor analysis for testing invariance revealed invariant measurement properties and factor structures across gender, indicating that task and ego orientation are similarly conceptualized by male and female students. Subsequent testing of latent mean structures, however, showed significant gender differences with respect to ego orientation, but no difference in task orientation. The SEM procedures used in the present study demonstrate additional construct validity and internal consistency reliability for the TEOSQ and, by confirming its factor structure, provide a sound psychometric basis for its continued use in substantive studies focusing on the comparison of achievement goal orientation across gender. 相似文献
24.
25.
26.
M Yazdanbakhsh WA Paxton YC Kruize E Sartono A Kurniawan A van het Wout ME Selkirk F Partono RM Maizels 《Canadian Metallurgical Quarterly》1993,167(4):925-931
To establish the relationships among T and B cell responses, active infection, and clinical manifestations in lymphatic filariasis, filarial-specific lymphocyte proliferation, IgG antibody isotypes, and IgE levels were determined in an exposed population: 31 asymptomatic amicrofilaremics, 43 microfilaremics, 12 symptomatic amicrofilaremics, and 52 elephantiasis patients. Lymphocyte proliferation was higher in elephantiasis patients and asymptomatic amicrofilaremics than in microfilaremics (P < .004). A proportion of asymptomatic amicrofilaremics (32%), elephantiasis patients (37%), and symptomatic amicrofilaremics (58%) showed antigen-specific lymphocyte unresponsiveness, and lymphocyte proliferation to filarial antigens correlated negatively with specific IgG4 levels (rho = -0.315, P < .001). As elevated specific IgG4 is an indicator of active infection, it is argued that active infection may result in lymphocyte hyporesponsiveness irrespective of clinical category. Of those with elevated specific IgE levels and high T cell proliferative responses, 70% had elephantiasis, suggesting these factors have a role in pathology. However, the existence of a proportion of elephantiasis patients with low anti-filarial IgE and T cell unresponsiveness to filarial antigens suggests that elephantiasis can be caused by distinct processes. 相似文献
27.
I have discussed a model of the psyche comprising two different modes of thinking, one non-psychotic and the other psychotic. I have related these modes of thinking to our modern myth of Jekyll and Hyde, the study of which could in my opinion give us some insight into their nature. In my view a non-psychotic state of mind belongs to a person who has a history, with particular parents, a particular development, particular conflicts, and operates in the depressive position. A psychotic state of mind belongs to a person who lives in a still and timeless present, with no origin, no development and no conflict, and operates in the paranoid-schizoid position. On the basis of this model I have subsequently described the life history of a psychotic patient and an analytic session in detail, showing how psychotic and non-psychotic states alternate and interact with each other within the same individual and between patient and therapist. The use of my countertransference, moving from a concrete to a symbolic position, has enabled me to make an interpretation. The result of this interpretation has been double, leading to a negative therapeutic reaction. An upsurge of psychotic fury was followed by increased patient/therapist communication, with a small movement from the paranoid-schizoid to the depressive position. 相似文献
28.
29.
In recent years the measurement of mold spore concentrations in working environments where workers spend long periods of time has acquired considerable importance because of the diffusion of diseases caused by fungi. On this basis, the aim of the research was to evaluate the level of environmental fungal pollution and contamination by mites in three factories producing seasoned foods, i.e., hams, sausages and cheeses. We also studied the occurrence of fungal species in the upper respiratory tract of workers operating in the washing and brushing areas, which was compared with the environmental concentrations in these areas, where contamination with fungal spores was visibly high. The results showed high and widespread fungal pollution in most of the working environments sampled and a significant presence of the same species in the upper respiratory tract of the workers. The data obtained indicate that the environments sampled can constitute a possible health risk factor for workers. 相似文献
30.