全文获取类型
收费全文 | 1884篇 |
免费 | 19篇 |
专业分类
电工技术 | 19篇 |
综合类 | 1篇 |
化学工业 | 181篇 |
金属工艺 | 11篇 |
机械仪表 | 17篇 |
建筑科学 | 60篇 |
矿业工程 | 1篇 |
能源动力 | 26篇 |
轻工业 | 201篇 |
水利工程 | 5篇 |
石油天然气 | 3篇 |
无线电 | 93篇 |
一般工业技术 | 179篇 |
冶金工业 | 893篇 |
原子能技术 | 10篇 |
自动化技术 | 203篇 |
出版年
2022年 | 7篇 |
2021年 | 10篇 |
2020年 | 12篇 |
2019年 | 26篇 |
2018年 | 21篇 |
2017年 | 26篇 |
2016年 | 13篇 |
2015年 | 14篇 |
2014年 | 12篇 |
2013年 | 82篇 |
2012年 | 43篇 |
2011年 | 58篇 |
2010年 | 44篇 |
2009年 | 41篇 |
2008年 | 54篇 |
2007年 | 55篇 |
2006年 | 52篇 |
2005年 | 44篇 |
2004年 | 52篇 |
2003年 | 41篇 |
2002年 | 34篇 |
2001年 | 32篇 |
2000年 | 27篇 |
1999年 | 46篇 |
1998年 | 224篇 |
1997年 | 137篇 |
1996年 | 98篇 |
1995年 | 64篇 |
1994年 | 57篇 |
1993年 | 65篇 |
1992年 | 18篇 |
1991年 | 19篇 |
1990年 | 18篇 |
1989年 | 29篇 |
1988年 | 17篇 |
1987年 | 23篇 |
1986年 | 24篇 |
1985年 | 26篇 |
1984年 | 11篇 |
1983年 | 8篇 |
1982年 | 15篇 |
1981年 | 18篇 |
1980年 | 12篇 |
1979年 | 19篇 |
1978年 | 10篇 |
1977年 | 29篇 |
1976年 | 65篇 |
1975年 | 14篇 |
1974年 | 9篇 |
1971年 | 7篇 |
排序方式: 共有1903条查询结果,搜索用时 10 毫秒
1.
2.
3.
P.O. Fanger B.M. Ipsen G. Langkilde B.W. Olessen N.K. Christensen S. Tanabe 《Energy and Buildings》1985,8(3):225-236
Groups of 32 and 16 subjects of both sexes were exposed in an environmental chamber to radiant asymmetry caused by a cool wall, a warm wall, and a cool ceiling. Each subject was tested individually while seated and clothed at 0.6 clo. During each 3.5-hour experiment the subject was exposed to six radiant temperature asymmetries. He was asked whether and where he experienced any local cool or warm sensation, and whether it was felt to be uncomfortable. During the entire experiment he was kept thermally neutral by changing the air temperature according to his wishes.For cool walls, warm walls, and cool ceilings curves have been established showing the percentage of dissatisfied subjects as a function of the radiant asymmetry. Radiant asymmetry at a warm wall caused less discomfort than a cool wall. A cool ceiling caused less discomfort than a warm ceiling. Accepting that 5% of the subjects may feel uncomfortable. a radiant temperature asymmetry of 10°C is allowable at a cool wall, 23°C at a warm wall, and 14°C under a cool ceiling. A previous study showed that 4°C is allowable under a warm ceiling. Radiant asymmetry had no significant impact on the operative temperatures preferred by the subjects. No significant differences were observed between the responses of men and women exposed to radiant asymmetry. 相似文献
4.
Networks are one of the most significant developments in computing and a hallmark of modern society. However, along with increasing efficiency and productivity, both at home and in the workplace, networks have costs. One cost is the additional energy that electronic devices consume when attached to networks. Power management, a standard feature of modern PCs, was primarily developed to increase battery lifetime in laptop PCs, which historically were not network-connected when using battery power. Today, however, many laptops are connected to a network - typically a Wi-Fi network - as are the majority of desktop computers. Three key drivers of energy use are induced consumption by devices prevented by network connections from entering low-power states, increasing link data rates that inherently consume more energy for the network interfaces, and proliferation of network-connected displays that actively update and display data when no one is present. 相似文献
5.
M Hessing D Kanters H Takeya C van 't Veer TM Hackeng S Iwanaga BN Bouma 《Canadian Metallurgical Quarterly》1993,317(3):228-232
Human C4b-binding protein (C4BP) functions as a cofactor to factor I in the degradation of C4b and accelerates the decay rate of the C4b2a complex. In this study we describe a monoclonal antibody directed against the alpha-chain of C4BP that inhibits the binding of C4b to C4BP. In order to identify the structural domain of the alpha-chain of C4BP that interacts with C4b, tryptic fragments of C4BP were generated. Amino acid sequence analysis of the fragments revealed that the residues Ser333-Arg356 of the alpha-chain of C4BP contain the epitope of this antibody, and as a consequence, that this part of the alpha-chain of C4BP is likely to be involved in the interaction with C4b. 相似文献
6.
K. Lefmann B. Lake G. Aeppli S.-W. Cheong N. B. Christensen K. N. Clausen S. Hayden T. E. Mason D.F. McMorrow H. A. Mook H. M. Rønnow H. Takagi 《Journal of Low Temperature Physics》2004,135(5-6):621-664
One important area of modern condensed matter research is the investigation of the nature of the superconducting cuprates. Much progress in this field has been obtained with the technique of neutron scattering. We here present a review of neutron scattering studies of the high-temperature superconductor La2?xSrxCuO4, performed at Risø National Laboratory. We review the work on the mapping of the incommensurate spin fluctuations, the investigation of the gap in the fluctuation spectrum, the magnetic properties of the vortices appearing in an applied field, and the quantum critical behaviour of the system. We discuss our findings in the light of results of neutron scattering from other groups, on other cuprate systems, and results from other experimental methods, e.g. NMR, μSR, STM, X-ray diffraction, and ARPES. We end with a discussion on the implications of the experimental results for the progress in the general understanding of high-temperature superconductivity. PACS numbers: 61.12.Ex, 74.20.Mn, 74.72.Dn, 75.25.+z, 78.70.Nx. 相似文献
7.
Richard M. Christensen 《International Journal of Fracture》2003,123(3-4):157-164
Failure surface orientations are determined for states of uniaxail tensile stress and shiar stree appropriate to fracture Modes I and II. The method uses a newly developed failure criterion along with the associated flow rule. The failure angles show a sharp demarcation between ductile and brittle material types. Only the brittle materials class show consistency and likely represents a shear localization effect rether than explicit fracture. 相似文献
8.
BN Mehrotra 《Canadian Metallurgical Quarterly》1996,51(1-3):161-165
Forests are the chief resource for the collection and exploration of biological materials. The past few decades have witnessed a large scale deforestation in India due to substantial pressures generated by population growth, leading to demand for more land for agriculture, urbanization and industrial activities, in addition to increased demand for fuel wood and timber. This has resulted in the loss of soil cover, habitat destruction, environmental degradation and ecological imbalance. This scenario has created a progressive awareness for the conservation and restoration of habitats and, thus, the declaration of many forest areas into protected zones, such as national parks, biosphere reserves, etc., including the protection of some marine areas, by both the National and State Governments. Normally, permission for biological collecting is not granted in these protected areas. In India, forests are a State subject and grant for collection permission is vested with the State Forest Departments. In the absence of any rules, regulations and guidelines, either from National or State Governments, forest authorities impose their terms and conditions, which are arbitrary and even contradictory at times, in the process of granting collecting permits. A set of new rules to be applied throughout the country is needed. 相似文献
9.
Plasma concentrations of gentamicin following a fixed dose of 240 mg once daily to patients with normal renal function were measured. The purpose was to establish guidelines to achieve a sufficiently high peak concentration with an appropriately low risk of accumulation. In 40 patients, 1-hour concentrations of plasma gentamicin had a median of 9.3 mg/l (range: 4.5-19.0 mg/l) and 9.7 mg/l (range: 3.6-14.6 mg/l) on days 1 and 3 of gentamicin treatment, respectively. Thirty-nine patients had 1-hour concentrations > 5 mg/l. The 1-hour concentrations varied considerably intra- and interindividually but showed a significant inverse correlation with body weight, surface area and the estimated endogenous creatinine clearance. The plasma gentamicin elimination half-life correlated significantly with age and inversely with body weight and creatinine clearance. There was no increase in the mean plasma creatinine from day 0 to day 4. No patients showed signs of nephrotoxicity, although 2 patients, both elderly and with low body weight, showed signs of beginning gentamicin accumulation. In conclusion, gentamicin treatment with the dose of 240 mg once daily in 3 days to adults with normal kidney function generally does not require adjustment or monitoring. However, the dose should be increased in young patients with an excessive body weight, and decreased doses are needed for old and underweight patients. Monitoring of trough plasma gentamicin concentration is not necessary with treatment duration of 3 days or less. 相似文献
10.