全文获取类型
收费全文 | 2651篇 |
免费 | 146篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 55篇 |
综合类 | 1篇 |
化学工业 | 642篇 |
金属工艺 | 57篇 |
机械仪表 | 43篇 |
建筑科学 | 71篇 |
矿业工程 | 1篇 |
能源动力 | 79篇 |
轻工业 | 267篇 |
水利工程 | 28篇 |
石油天然气 | 20篇 |
无线电 | 313篇 |
一般工业技术 | 396篇 |
冶金工业 | 452篇 |
原子能技术 | 25篇 |
自动化技术 | 350篇 |
出版年
2023年 | 16篇 |
2022年 | 49篇 |
2021年 | 62篇 |
2020年 | 54篇 |
2019年 | 63篇 |
2018年 | 69篇 |
2017年 | 81篇 |
2016年 | 103篇 |
2015年 | 78篇 |
2014年 | 118篇 |
2013年 | 148篇 |
2012年 | 101篇 |
2011年 | 148篇 |
2010年 | 108篇 |
2009年 | 124篇 |
2008年 | 111篇 |
2007年 | 112篇 |
2006年 | 89篇 |
2005年 | 73篇 |
2004年 | 68篇 |
2003年 | 65篇 |
2002年 | 76篇 |
2001年 | 45篇 |
2000年 | 35篇 |
1999年 | 41篇 |
1998年 | 145篇 |
1997年 | 84篇 |
1996年 | 73篇 |
1995年 | 62篇 |
1994年 | 45篇 |
1993年 | 44篇 |
1992年 | 23篇 |
1991年 | 25篇 |
1990年 | 24篇 |
1989年 | 19篇 |
1988年 | 18篇 |
1987年 | 24篇 |
1986年 | 23篇 |
1985年 | 18篇 |
1984年 | 21篇 |
1983年 | 13篇 |
1981年 | 11篇 |
1980年 | 6篇 |
1979年 | 9篇 |
1977年 | 6篇 |
1976年 | 19篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1973年 | 6篇 |
1970年 | 7篇 |
排序方式: 共有2800条查询结果,搜索用时 15 毫秒
71.
Catechin and quercetin attenuate adipose inflammation in fructose‐fed rats and 3T3‐L1 adipocytes 下载免费PDF全文
72.
73.
Gerardo del Cerro Santamaría 《Journal of the American Planning Association. American Planning Association》2013,79(1):101-102
In this article, we review three microcomputer programs for assessing regional economic impacts. The programs are ADOTMATR, GRIMP, and REMI, which we discuss in terms of their suitability for policy analysis and planning practice. We assess the programs in terms of range of applicability, flexibility and ease of use in conducting impact analyses, quality of output, and cost. ADOTMATR and GRIMP are similar; however, GRIMP is easier to use but less flexible and more limited than ADOTMATR. Although REMI is more sophisticated than the other two programs, it is more expensive and more limited in application. 相似文献
74.
75.
M. G. Roig J. F. Bello S. Rodriguez J. F. Kennedy D. W. Taylor 《Polymer International》1996,39(1):17-30
Alkaline phosphatase from human placenta has been chemically immobilized on a hydrophilic cross-flow microfiltration membrane made from poly(vinylidene difluoride) (PVDF) derivatized with 1,1′-carbonyldiimidazole. The physicochemical characterization of the immobilized biocatalyst paid special attention to the irreversibility of the bonding of the enzyme to the support, the effects of pH, temperature and ionic strength on this activity, the existence of limitations of internal and external diffusion for H+, substrate and/or products, and the kinetic behavior (intrinsic and/or effective) of the immobilized enzyme. With respect to enzyme stability, patterns of hysteresis or memory are proposed, to account for a catalytic activity affected by previous experimental events and situations. The intrinsic kinetic behaviour, rate versus substrate concentration in the absence of diffusional restrictions, was analysed graphically and numerically (by non-linear regression and by utilizing the F statistical test for model discrimination), postulating a minimum rational rate equation of 2:2 degree in substrate concentration. In concordance, a mechanistic kinetic scheme for the catalytic enzyme action has been postulated. 相似文献
76.
H. Ahn C. Pfohl J. Whle A. Gebauer S. Biemer A. Bulak E. Menthe E. Rodriguez Cabeo T. Stucky A. Gebauer 《Materialwissenschaft und Werkstofftechnik》1996,27(12):573-583
Develpoment of wear and corrosion resistant surface systems In this study two methods are described to realize wear and corrosion resistant surface systems: Plasma diffusion treatment (PDT) and Plasma assited CVD (PACVD). Plasma nitriding, Plasma nitrocarburizing and plasma boriding are used to treat different kinds of substrates. The advances of PACVD and the development of low temperature PACVD and industrial applications of these techniques are explained. 相似文献
77.
Infrared spectra demonstrate the use of computer difference spectroscopy and other dataprocessing routines to derive and enhance the difference spectra that relates the concentration of a resin to the concentration of other resins in the mixture. Therefore, a simple quantitative treatment accounting for the resin concentration has been determined. © 1995 John Wiley & Sons, Inc. 相似文献
78.
Jorge Berlanga-Acosta Maday Fernndez-Mayola Yssel Mendoza-Marí Ariana García-Ojalvo Indira Martinez-Jimenez Nadia Rodriguez-Rodriguez Raymond J. Playford Osvaldo Reyes-Acosta Laura Lopez-Marín Gerardo Guilln-Nieto 《International journal of molecular sciences》2022,23(3)
Lower-extremity arterial disease is a major health problem with increasing prevalence, often leading to non-traumatic amputation, disability and mortality. The molecular mechanisms underpinning abnormal vascular wall remodeling are not fully understood. We hypothesized on the existence of a vascular tissue memory that may be transmitted through soluble signaling messengers, transferred from humans to healthy recipient animals, and consequently drive the recapitulation of arterial wall thickening and other vascular pathologies. We examined the effects of the intralesional infiltration for 6 days of arteriosclerotic popliteal artery-derived homogenates (100 µg of protein) into rats’ full-thickness wounds granulation tissue. Animals infiltrated with normal saline solution or healthy brachial arterial tissue homogenate obtained from traumatic amputation served as controls. The significant thickening of arteriolar walls was the constant outcome in two independent experiments for animals receiving arteriosclerotic tissue homogenates. This material induced other vascular morphological changes including an endothelial cell phenotypic reprogramming that mirrored the donor’s vascular histopathology. The immunohistochemical expression pattern of relevant vascular markers appeared to match between the human tissue and the corresponding recipient rats. These changes occurred within days of administration, and with no cross-species limitation. The identification of these “vascular disease drivers” may pave novel research avenues for atherosclerosis pathobiology. 相似文献
79.
Paola Maura Tricarico Donatella Mentino Aurora De Marco Cecilia Del Vecchio Sabino Garra Gerardo Cazzato Caterina Foti Sergio Crovella Giuseppe Calamita 《International journal of molecular sciences》2022,23(7)
The skin is the largest organ of the human body, serving as an effective mechanical barrier between the internal milieu and the external environment. The skin is widely considered the first-line defence of the body, with an essential function in rejecting pathogens and preventing mechanical, chemical, and physical damages. Keratinocytes are the predominant cells of the outer skin layer, the epidermis, which acts as a mechanical and water-permeability barrier. The epidermis is a permanently renewed tissue where undifferentiated keratinocytes located at the basal layer proliferate and migrate to the overlying layers. During this migration process, keratinocytes undertake a differentiation program known as keratinization process. Dysregulation of this differentiation process can result in a series of skin disorders. In this context, aquaporins (AQPs), a family of membrane channel proteins allowing the movement of water and small neutral solutes, are emerging as important players in skin physiology and skin diseases. Here, we review the role of AQPs in skin keratinization, hydration, keratinocytes proliferation, water retention, barrier repair, wound healing, and immune response activation. We also discuss the dysregulated involvement of AQPs in some common inflammatory dermatological diseases characterised by skin barrier disruption. 相似文献
80.
Effects of dietary supplements of zinc-methionine on milk production,udder health and zinc metabolism in dairy goats 总被引:5,自引:0,他引:5
Salama AA Caja G Albanell E Such X Casals R Plaixats J 《The Journal of dairy research》2003,70(1):9-17
Twenty-two Murciano-Granadina dairy goats were used to investigate the effects of organic Zn supplementation of a diet containing a high level of inorganic Zn. Goats were kept in pens, machine milked once a day throughout lactation and fed a diet based on a dehydrated mixture of whole-plant maize and alfalfa ad libitum, alfalfa pellets, barley grain and a concentrate mixture. Treatments were: (1) control, and (2) supplemented with 1 g/d Zn-Methionine (Zn-Met) included in the concentrate mixture. After parturition, goats were blocked in week 3 and dietary treatments were applied until week 23. From weeks 3-20, feed intake, milk yield, milk composition, milk somatic cell count (SCC), and udder health were measured. In week 21, all goats were injected intraperitoneally with 1 g/d DL-methionine for 5 d to establish the effects of methionine under the conditions of udder stress induced by hand milking on the second day. During weeks 22 and 23, diet digestibility, and N and Zn balance were determined. Dry matter intake, milk yield, and milk contents of total solids, fat, total and true protein, and casein did not differ between treatments, but whey protein and non-protein nitrogen contents were significantly lower for the Zn-Met group. Milk SCC tended to decrease as a result of Zn-Met supplementation but differences between treatments were not significant when halves with persistent infection were excluded. Hand milking increased SCC in both groups, but udders of supplemented goats showed a lower reaction. Apparent absorption of N significantly increased and Zn retention tended to increase in Zn-Met supplemented goats. We conclude that Zn-Met supplementation can enhance resistance to udder stress in dairy goats. Effects were attributed to the organic Zn and not to the methionine component. Zn retention and protein utilization were also improved by the Zn-Met supplement. 相似文献