全文获取类型
收费全文 | 6333篇 |
免费 | 305篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 55篇 |
综合类 | 4篇 |
化学工业 | 1122篇 |
金属工艺 | 64篇 |
机械仪表 | 79篇 |
建筑科学 | 159篇 |
矿业工程 | 18篇 |
能源动力 | 177篇 |
轻工业 | 795篇 |
水利工程 | 24篇 |
石油天然气 | 16篇 |
无线电 | 212篇 |
一般工业技术 | 717篇 |
冶金工业 | 2177篇 |
原子能技术 | 21篇 |
自动化技术 | 1000篇 |
出版年
2024年 | 10篇 |
2023年 | 44篇 |
2022年 | 159篇 |
2021年 | 199篇 |
2020年 | 125篇 |
2019年 | 148篇 |
2018年 | 186篇 |
2017年 | 177篇 |
2016年 | 179篇 |
2015年 | 154篇 |
2014年 | 193篇 |
2013年 | 339篇 |
2012年 | 329篇 |
2011年 | 362篇 |
2010年 | 283篇 |
2009年 | 242篇 |
2008年 | 255篇 |
2007年 | 211篇 |
2006年 | 165篇 |
2005年 | 147篇 |
2004年 | 105篇 |
2003年 | 101篇 |
2002年 | 93篇 |
2001年 | 44篇 |
2000年 | 39篇 |
1999年 | 99篇 |
1998年 | 708篇 |
1997年 | 405篇 |
1996年 | 268篇 |
1995年 | 173篇 |
1994年 | 108篇 |
1993年 | 128篇 |
1992年 | 21篇 |
1991年 | 30篇 |
1990年 | 42篇 |
1989年 | 42篇 |
1988年 | 25篇 |
1987年 | 17篇 |
1986年 | 16篇 |
1985年 | 18篇 |
1984年 | 14篇 |
1983年 | 14篇 |
1982年 | 14篇 |
1981年 | 21篇 |
1980年 | 15篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1977年 | 42篇 |
1976年 | 82篇 |
1975年 | 15篇 |
排序方式: 共有6640条查询结果,搜索用时 218 毫秒
31.
Two patients are presented where internal mammary artery grafting was performed for the relief of symptomatic coronary artery disease. At follow-up the internal mammary artery was occluded and a communication between the internal mammary vein and the native coronary artery was demonstrated. These patients were characterised by the early recurrence of angina or the appearance of a continuous murmur. Both patients were treated by re-operation with ligation of the arterio-venous fistula and saphenous vein grafting. 相似文献
32.
Resisting care is defined as any patient behavior which prevents or interferes with the care provider performing or assisting with ADLs for the patient, including bathing, eating, toileting, dressing and grooming. Significant consequences of resisting care include malnutrition, skin breakdown, dehydration, constipation and weight loss. Creativity, flexibility and patience are key components of any intervention. Due to the lability of the person with cognitive impairment, a plan that works perfectly one day may never work again. 相似文献
33.
MF Good 《Canadian Metallurgical Quarterly》1994,41(2-3):123-125
An approach to identification of epitopes suitable for vaccine development has been to locate regions of malaria target antigens that are recognized by individuals with clinical immunity. This has applied to identification of T- and B-cell epitopes. It is now realized, however, that T cells from individuals without prior exposure to malaria can respond to malaria parasites, malaria proteins, and peptides copying protein sequences. Such observations raise questions about which epitopes we should be targeting for vaccine development, but also challenge our understanding of immunological memory. Such responses from non-exposed individuals may also be important in expression of disease symptoms. 相似文献
34.
MF Berthault J Morin M Dubar A Ktorza P Ferré L Pénicaud 《Canadian Metallurgical Quarterly》1996,89(8):1103-1106
This study was aimed to determine the effects of rilmenidine, an hypertensive drug, in an animal model of hypertension associated with insulin resistance, i.e. rats fed on a high fructose diet. Wistar rats were fed during four weeks either on a standard diet (S) or on a high fructose diet (F, 34.5% de fructose). In half of the F groups, rilmenidine (1 mg/kg/day) was added to the drinking water during the two last weeks of the diet (FR). Arterial blood pressure as well as insulin efficiency were determined at the end of the four weeks. Body weight gain was higher in F than in S rats (66 +/- 8 g versus 45 +/- 8 g; p < 0.05), this was prevented by rilmenidine treatment (32 +/- 2 g). Arterial systolic blood pressure was increased in F rats (162 +/- 2 vs 155 +/- 2 mmHg; p < 0.05), rilmenidine brought this value back to normal (149 +/- 3 mmHg). During the euglycemic hyperinsulinemic clamp, glucose utilization was lower (10 +/- 1 vs 14 +/- 1.5 mg/min/kg; p < 0.05) and hepatic glucose production higher (1 +/- 0.01 vs 0 mg/min/kg; p < 0.01) in F than in S rats. These changes in insulin action were totally abolished by rilmenidine. These data demonstrate that rilmenidine can ameliorate the deleterious effects of a high fructose diet, i.e. weight gain, hypertension and resistance to the effects of insulin Rilmenidine could represent a potential therapeutic agent for the treatment of hypertension associated with metabolic disorders such as syndrom X and obesity. 相似文献
35.
Abstract: Environmental justice advocates have recently focused attention on cumulative exposure in minority neighborhoods due to multiple sources of pollution. This article uses U.S. EPA's National Air Toxics Assessment (NATA) for 1996 to examine environmental inequality in California, a state that has been a recent innovator in environmental justice policy. We first estimate potential lifetime cancer risks from mobile and stationary sources. We then consider the distribution of these risks using both simple comparisons and a multivariate model in which we control for income, land use, and other explanatory factors, as well as spatial correlation. We find large racial disparities in California's “riskscape” as well as inequalities by other factors and suggest several implications for environmental and land use policy. 相似文献
36.
37.
Do individual factors matter? A survey of scientists’ patenting in Portuguese public research organisations 总被引:1,自引:0,他引:1
Paula Susana Figueiredo Moutinho Margarida Fontes Manuel Mira Godinho 《Scientometrics》2007,70(2):355-377
This paper addresses scientists’ behaviour regarding the patenting of knowledge produced in universities and other public
sector research organisations (PSROs). Recent years have witnessed a rapid growth in patenting and licensing activities by
PSROs. We argue that the whole process depends to a certain extent on scientists’ willingness to disclose their inventions.
Given this assumption, we conduct research into individual behaviour in order to understand scientists’ views concerning the
patenting of their research results. Data from a questionnaire survey of Portuguese researchers from nine PSROs in life sciences
and biotechnology is presented and analysed and complemented with in-depth interviews. The results reveal that overall the
scientists surveyed show a low propensity to become involved in patenting and licensing activities, despite the fact that
the majority had no “ethical” objections to the disclosure of their inventions and the commercial exploitation of these. Perceptions
about the impacts of these activities on certain fundamental aspects of knowledge production and dissemination are however
divergent. This may account for the low participation levels. Furthermore, most scientists perceived the personal benefits
deriving from this type of activity to be low. Similarly, the majority also believed that there are many difficulties associated
with the patenting process and that they receive limited support from their organisations, which lack the proper competences
and structures to assist with patenting and licensing. 相似文献
38.
Manuel Landajo 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2004,34(1):645-651
Nonparametric estimation capabilities of fuzzy systems in stochastic environments are analyzed in this paper. By using ideas from sieve estimation, increasing sequences of fuzzy rule-based systems capable of consistently estimating arbitrary regression surfaces are constructed. Results include least squares learning of a mapping perturbed by additive random noise in a static-regression context. L1 (i.e., least absolute deviation) estimation is also studied, and the consistency of fuzzy rule-based sieve estimators for L1-optimal regression surfaces is shown, thus giving additional theoretical support to the robust filtering capabilities of fuzzy systems and their adequacy for modeling, prediction, and control of systems affected by impulsive noise. 相似文献
39.
F Zindy H Soares KH Herzog J Morgan CJ Sherr MF Roussel 《Canadian Metallurgical Quarterly》1997,8(11):1139-1150
In situ hybridization of mouse embryo sections demonstrated expression of mRNAs encoding two polypeptide inhibitors (p18INK4c and p19INK4d) of cyclin D-dependent kinase (CDK) 4 and CDK6 in the central nervous system. No expression of two other INK4 members, p16INK4a and p15INK4b, was observed. The p19INK4d and p18INK4c proteins formed complexes with either CDK4 or CDK6 in a temporal pattern consistent with the results of in situ hybridization. Expression of INK4c was observed at embryonic day 13.5 in neuroepithelial zones of the developing brain, being restricted to dividing neuroblasts but absent from differentiating postmitotic neurons. In the neocortex, p18INK4c was expressed precisely at those developmental stages when neuroblasts switch from a symmetric to an asymmetric pattern of cell division with concomitant increases in their G1 interval. INK4d RNA was detected from embryonic day 11.5 onward, at higher levels than INK4c and with a distinctly different spatial and temporal pattern. Marked INK4d expression was seen in dorsal root ganglia, spinal cord, and focally throughout the brain, but primarily in postmitotic neurons. Neural expression of INK4d continued postnatally into adulthood in postmitotic cells of the dentate gyrus, the pyramidal layer of the hippocampus, and in discrete regions of the cerebral cortex, cerebellum, thalamus, and brainstem. Downregulation of p19INK4d in the dentate gyrus after kainic acid-induced seizures indicated that its expression could also be modified in nondividing cells by excitotoxic stress. Therefore, p19INK4d may contribute to maintaining the quiescent state, acting as a buffer to prevent reactivation of cyclin D-dependent kinases in terminally differentiated cells. 相似文献
40.
Martine Decloux Manuel Dornier & Isabelle Gratius 《International Journal of Food Science & Technology》1996,31(2):153-166
Gum arabic is a natural gum exuded mainly by the trees Acacia senegal , currently used in the food industries for its emulsifying, thickening and stabilizing properties. Its present processing includes various operations providing a quite turbid product. Crossflow microfiltration could be interesting for the clarification and the cold-pasteurization of the gum arabic solutions. Several experiments were therefore made with the crossflow microfiltration unit at ENSIA, using two different systems: the classical one (without permeate circulation), and the co-current permeate flow system (CCPF) allowing the exploration of the low transmembrane pressures range. With gum arabic solutions of 0.17g solids g−1 solution and 70°C, the best results after 60 min of filtration (105.7 L h−1 m−2 , 4.4% of solids retention and 83.4% of clarification) were obtained with the CCPF system at low transmembrane pressure and high crossflow velocity (0.3 bar and 7.5ms−1 ). 相似文献