全文获取类型
收费全文 | 2477篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 42篇 |
金属工艺 | 3篇 |
机械仪表 | 9篇 |
建筑科学 | 2篇 |
轻工业 | 14篇 |
水利工程 | 1篇 |
无线电 | 18篇 |
一般工业技术 | 75篇 |
冶金工业 | 2295篇 |
原子能技术 | 5篇 |
自动化技术 | 13篇 |
出版年
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 6篇 |
2013年 | 8篇 |
2012年 | 10篇 |
2011年 | 11篇 |
2010年 | 13篇 |
2009年 | 10篇 |
2008年 | 18篇 |
2007年 | 11篇 |
2006年 | 13篇 |
2005年 | 14篇 |
2004年 | 5篇 |
2003年 | 15篇 |
2002年 | 5篇 |
2001年 | 10篇 |
2000年 | 6篇 |
1999年 | 79篇 |
1998年 | 725篇 |
1997年 | 443篇 |
1996年 | 258篇 |
1995年 | 134篇 |
1994年 | 99篇 |
1993年 | 128篇 |
1992年 | 22篇 |
1991年 | 18篇 |
1990年 | 20篇 |
1989年 | 28篇 |
1988年 | 35篇 |
1987年 | 19篇 |
1986年 | 17篇 |
1985年 | 12篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 17篇 |
1978年 | 4篇 |
1977年 | 62篇 |
1976年 | 144篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1968年 | 2篇 |
1959年 | 1篇 |
1955年 | 3篇 |
排序方式: 共有2482条查询结果,搜索用时 62 毫秒
31.
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
32.
33.
34.
35.
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
36.
Patrick J. McNally 《Solid-state electronics》1992,35(12):1705-1708
The use of two generalised carrier transport models to account for the ND−1 dependence of the specific contact resistance (ρc) of metal-semiconductor Ohmic contacts to n-type GaAs is proposed. Both models include the effects of thermionic emission and diffusion across the high-low barrier junction a priori. Calculations of ρc, and comparison with experimental data, show conclusively that thermionic emission is the dominant transport mechanism across the barrier. It is stressed that these models do not rely on prior choices of either of the transport processes. These conclusions are arrived at a posteriori. 相似文献
37.
38.
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
39.
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
40.
This paper presents the results of a longitudinal psychosocial study of 22 cranial trauma patients and 14 stroke patients from the time preceding injury (using retrospective data), through a 4-5 month intensive rehabilitation programme, to a follow-up 1 year after completion of the programme. Although the two groups of patients differed on several demographic and medical characteristics, essentially similar patterns for psychosocial decline following injury and improvement following rehabilitation could be observed. For both groups, the proportion in marital or cohabitational relationships returned to pre-injury levels, and for both groups the proportion requiring assistance in their living situation declined following rehabilitation, as did use of the health services. Virtually all patients in both groups had been in employment or undergoing education at the time of the injury, and although this percentage declined in practice to a small minority of both groups post-injury, there was a significant increase in the proportions working or in education following the rehabilitation programme. Similarly, the pattern of leisure-time activities in both groups declined post-injury and was restored following rehabilitation. Since both groups entered the programme at over 2.5 years post-injury, these generally encouraging results seem less likely to reflect spontaneous recovery than a beneficial effect of the programme itself. 相似文献