全文获取类型
收费全文 | 5057篇 |
免费 | 39篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 36篇 |
综合类 | 1篇 |
化学工业 | 353篇 |
金属工艺 | 33篇 |
机械仪表 | 54篇 |
建筑科学 | 108篇 |
矿业工程 | 2篇 |
能源动力 | 44篇 |
轻工业 | 249篇 |
水利工程 | 17篇 |
石油天然气 | 5篇 |
无线电 | 229篇 |
一般工业技术 | 377篇 |
冶金工业 | 3122篇 |
原子能技术 | 36篇 |
自动化技术 | 432篇 |
出版年
2023年 | 11篇 |
2022年 | 31篇 |
2021年 | 62篇 |
2020年 | 18篇 |
2019年 | 38篇 |
2018年 | 44篇 |
2017年 | 31篇 |
2016年 | 37篇 |
2015年 | 24篇 |
2014年 | 58篇 |
2013年 | 104篇 |
2012年 | 95篇 |
2011年 | 138篇 |
2010年 | 91篇 |
2009年 | 106篇 |
2008年 | 119篇 |
2007年 | 100篇 |
2006年 | 77篇 |
2005年 | 87篇 |
2004年 | 73篇 |
2003年 | 76篇 |
2002年 | 63篇 |
2001年 | 57篇 |
2000年 | 51篇 |
1999年 | 134篇 |
1998年 | 1052篇 |
1997年 | 647篇 |
1996年 | 359篇 |
1995年 | 206篇 |
1994年 | 175篇 |
1993年 | 207篇 |
1992年 | 46篇 |
1991年 | 34篇 |
1990年 | 41篇 |
1989年 | 47篇 |
1988年 | 55篇 |
1987年 | 34篇 |
1986年 | 32篇 |
1985年 | 32篇 |
1984年 | 22篇 |
1983年 | 13篇 |
1982年 | 21篇 |
1981年 | 15篇 |
1980年 | 22篇 |
1978年 | 9篇 |
1977年 | 75篇 |
1976年 | 158篇 |
1975年 | 12篇 |
1974年 | 7篇 |
1969年 | 7篇 |
排序方式: 共有5098条查询结果,搜索用时 9 毫秒
21.
F Boersma JA Eefsting W van den Brink W van Tilburg 《Canadian Metallurgical Quarterly》1995,26(2):57-64
In the Netherlands both nursing homes and homes for the aged serve as a residence for demented elderly. Although these institutions differ considerably regarding financing and care facilities, specific functions of each institute concerning demented elderly have not been clearly defined. In order to know to what extent residential facilities serve demented elderly, the prevalence and severity of dementia among residents aged 65 and over was studied as part of a prevalence study among elderly people in a rural area of the Netherlands. The target population existed of all persons aged 65 and over who were registered in eight general practices. Patients who had to leave the practice on account of ill-health and were admitted to nursing homes were included in the study. In a two stage study the MMSE was applied as a screening instrument. Based on MMSE-score a non-proportional stratified random sample was drawn for the second, diagnostic stage, which existed of the CAMDEX. Prevalence estimates for DSM-III-R-dementia were 21% among residents of homes for the aged, 48% among residents of somatic wards of nursing homes and 100% among those admitted to psychogeriatric wards of nursing homes. Severity of dementia was highest among residents of psychogeriatric wards of nursing homes and lowest among those living in homes for the aged. Prevalence of dementia among residents of homes for the aged can be fully attributed to the age-distribution. The high frequency of dementia among residents of somatic nursing home wards can be explained in several ways: First, admission can be necessary due to a combination of dementia and somatic illness.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
22.
IuA Magakian EM Karalova LO Abroian SA Karapetian 《Canadian Metallurgical Quarterly》1997,39(8):705-710
Cytophotometry of rat blood erythroid cells during anaemia, induced by phenylhydrazin (4-8 days from the beginning of injections), revealed that all forms of bone marrow containing haemoglobin were thrown into the blood. On its peak (4th day), the greatest contribution in blood haemoglobinization (50%) is made by microcytes. From the 5th day and up to the end of the restoration period the important role in this process is played by macrocytes. From the 6th day the role of normocytes increases, whose contribution by 8th day reaches 70% of the whole haemoglobin amount in blood. In contrary to anaemizated birds, whose erythroid cells ripen in blood, in rats all the transformations of erythron during anaemia are accomplished in bone marrow. 相似文献
23.
24.
25.
EM Prvulovich JB Bomanji WA Waddington P Rudrasingham AM Verbruggen PJ Ell 《Canadian Metallurgical Quarterly》1997,38(5):809-814
1. Effects of feeding condition from birth were examined on the sensitivity of neuromuscular transmission to d-tubocurarine (dTc) in vitro in male mice of the ddY strain. 2. Mice were trained to climb two separated cylindrical steel-wire tubes for feeding and drinking, respectively, from 16 days of age. Some mice were conventionally fed, from 99 days of age. Nerve-muscle preparations were made from the left phrenic nerve diaphragm muscle (DPH), the sciatic nerve soleus muscle (SOL), and the sciatic nerve extensor digitorum longus muscle (EDL) of 99-day-old and 155-day-old mice. The nerve trunk was electrically activated with trains of four pulses and tetanic pulses. 3. The sensitivity to the effects of dTc decreased in the order EDL, SOL, and DPH. This result held true in all mice tested. 4. This sensitivity was significantly potentiated by the compulsory movement. 5. The supersensitivity remained even when mice were conventionally fed after 99 days of age. 6. The compulsion rendered EDL antifatigable on tetanic stimulation. This property was also retained after a return to conventional feeding. 7. These results suggest that the effects of feeding condition from birth might remain on neuromuscular functions after termination of the conditioning. 相似文献
26.
27.
28.
Martijn Hendriks Barend van den Nieuwelaar Frits Vaandrager 《International Journal on Software Tools for Technology Transfer (STTT)》2006,8(6):633-647
For a case-study of a wafer scanner from the semiconductor industry it is shown how model checking techniques can be used
to compute (1) a simple yet optimal deadlock avoidance policy, and (2) an infinite schedule that optimizes throughput. in
the absence of errors. Deadlock avoidance is studied based on a simple finite state model using Smv, and for throughput analysis a more detailed timed automaton model has been constructed and analyzed using the Uppaal tool. The Smv and Uppaal models are formally related through the notion of a stuttering bisimulation. The results were obtained within 2 weeks, which
confirms once more that model checking techniques may help to improve the design process of realistic, industrial systems.
Methodologically, the case study is interesting since two models were used to obtain results that could not have been obtained
using only a single model.
Supported by the European Community Project IST-2001-35304 (Ametist), http://ametist.cs.utwente.nl/. 相似文献
29.
Coulter counting and light diffraction techniques were successfully applied to the characterisation of the droplet concentration and size distribution in camphene-water and cyclohexane-water emulsions. Both of these techniques required a dilution of the emulsion prior to analysis, and it was found that the destabilizing effect on the droplets of such dilution could be overcome by performing the analyses at temperatures below the melting point of the oil phase. The storage stability of the camphene-water samples at 60 degrees C was reasonably good with a 5-20% change in the investigated parameters over a 24 h period. At room temperature camphene-water samples left to stand undisturbed were unaffected after 24 h, while continuous mixing of the emulsion on a roller board brought about a rapid amalgamation of the particles into larger aggregates. This fusion process was fully described only with the light diffraction analysis due to the broader measuring range of this technique. However, analysing emulsions with a droplet size range covered by both techniques gave identical results. 相似文献
30.
A new technique for right heart catheterization using a Mullins' sheath is described. This device allows a Swan-Ganz catheter to reach pulmonary artery position easily and permits simultaneous pressure recordings in right heart chambers, thus avoiding a double venous puncture and two catheters. This new technique, its indications, and our experience in 29 patients are described. It is most useful in patients with severe pulmonary hypertension and in those conditions in which accurate right heart pressure measurements are needed. 相似文献