全文获取类型
收费全文 | 406123篇 |
免费 | 11401篇 |
国内免费 | 4962篇 |
专业分类
电工技术 | 10923篇 |
技术理论 | 11篇 |
综合类 | 6751篇 |
化学工业 | 65763篇 |
金属工艺 | 17696篇 |
机械仪表 | 15395篇 |
建筑科学 | 15950篇 |
矿业工程 | 4927篇 |
能源动力 | 9984篇 |
轻工业 | 33047篇 |
水利工程 | 4955篇 |
石油天然气 | 13306篇 |
武器工业 | 708篇 |
无线电 | 45625篇 |
一般工业技术 | 72218篇 |
冶金工业 | 58832篇 |
原子能技术 | 8866篇 |
自动化技术 | 37529篇 |
出版年
2022年 | 4240篇 |
2021年 | 6189篇 |
2020年 | 4730篇 |
2019年 | 4631篇 |
2018年 | 6777篇 |
2017年 | 7107篇 |
2016年 | 6986篇 |
2015年 | 6435篇 |
2014年 | 9307篇 |
2013年 | 18755篇 |
2012年 | 13661篇 |
2011年 | 16776篇 |
2010年 | 14084篇 |
2009年 | 15093篇 |
2008年 | 15387篇 |
2007年 | 14890篇 |
2006年 | 14166篇 |
2005年 | 12985篇 |
2004年 | 10708篇 |
2003年 | 9987篇 |
2002年 | 9648篇 |
2001年 | 9353篇 |
2000年 | 9156篇 |
1999年 | 9740篇 |
1998年 | 17742篇 |
1997年 | 13661篇 |
1996年 | 10940篇 |
1995年 | 8564篇 |
1994年 | 7554篇 |
1993年 | 7107篇 |
1992年 | 5547篇 |
1991年 | 5235篇 |
1990年 | 4946篇 |
1989年 | 4890篇 |
1988年 | 4732篇 |
1987年 | 3980篇 |
1986年 | 3884篇 |
1985年 | 4425篇 |
1984年 | 4164篇 |
1983年 | 3785篇 |
1982年 | 3563篇 |
1981年 | 3684篇 |
1980年 | 3518篇 |
1979年 | 3450篇 |
1978年 | 3539篇 |
1977年 | 3992篇 |
1976年 | 5119篇 |
1975年 | 3210篇 |
1974年 | 3046篇 |
1973年 | 3065篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
A G?rling 《Canadian Metallurgical Quarterly》1993,47(4):2783-2799
92.
M Valenti G Cimoli S Parodi GL Mariani M Venturini P Conte P Russo 《Canadian Metallurgical Quarterly》1993,(8):1157-1161
Synergism between recombinant human tumour necrosis factor (rHuTNF) and DNA topoisomerase II inhibitor VP16 during the killing of cells has been studied in six human ovarian cancer cell lines (A2774, A2780, SW626, IGROV-1, SKOV3, Pa1) and a cervical carcinoma cell line (Me180). Studies were performed using an assay of colony formation inhibition (drug treatment for 1 h) and a growth inhibition assay (continuous exposure for 20 h). Concomitant treatment of cells with VP16+rHuTNF enhanced cell killing in all the cell lines tested--an effect observed in both short- and long-term cytotoxicity assays. This study suggests that the activity of VP16 in ovarian cancer cell lines might be enhanced by rHuTNF in in vitro models. 相似文献
93.
A. G. Strunina 《Journal of Engineering Physics and Thermophysics》1993,65(4):953-956
The process of combustion of homogeneous and heterogeneous nongasifying and slightly gasifying systems over the range of a number of parameters characterizing the reactive composition and the conditions for the arrangement of the combustion process is studied by using thermocouple and optical methods. The regions of the implementation of different combustion regimes, namely, steady, pulsating, multiple-point, and spin, are determined experimentally.Institute of Structural Macrokinetics, Russian Academy of Sciences, Chernogolovka. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 4, pp. 407–411, October, 1993. 相似文献
94.
Sh. V. Gedevanishvili V. I. Yukhvid G. Sh. Oniashvili 《Journal of Engineering Physics and Thermophysics》1993,65(5):1134-1137
Use of inexpensive ore concentrates as initial components in SHS metallurgy [1–3] brings about some specific features in the process and the properties of the materials obtained. Ore reagents contain a considerable amount of impurities (Al2O3, SiO2, Fe2O3) that decrease the energetics of SHS systems and the temperature and the rate of combustion and create the limits of combustion and phase separation. In addition, the impurities participate in chemical reactions and enter the desired product. In many cases the presence of silicon, iron, and aluminum in a cast product does not prevent use of this product for practical purposes.Institute of Metallurgy, Academy of Sciences of the Republic of Georgia, Tbilisi. Institute of Structural Macrokinetics, Russian Academy of Sciences, Chernogolovka. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 5, pp. 613–616, November, 1993. 相似文献
95.
96.
97.
STRONG METAL-CERAMIC JOINTS 总被引:3,自引:0,他引:3
In this paper the technology for joining metals to ceramics is reviewed. The technologies of metal powder sintering, liquid phase joining with activated brazing alloys and with ceramic frit, solid-state joining, friction welding and mechanical fixation are described. In order to put some perspective on the mechanical data given in the literature, some evaluating remarks on mechanical testing are made. 相似文献
98.
E Campagnutta R Cannizzaro M De Cicco G De Piero G Giorda F Sopracordevole A Parin C Scarabelli 《Canadian Metallurgical Quarterly》1998,50(7-8):305-311
BACKGROUND AND AIMS: Intestinal obstruction is a frequent cause of death in patients suffering from gynecological cancer, who have undergone multiple treatment in the form of surgery and/or chemotherapy and/or radiotherapy. The usual form of rescue treatment consists in the use of a nasogastric tube to administer support and analgesic treatment. Surgical gastrostomy is not a viable proposition in these extremely weak patients with large masses compressing and displacing the stomach. Percutaneous endoscopic gastrostomy (PEG), a technique first introduced for nutritional purposes, can be beneficially used to achieve decompression in these patients. METHODS: PEG was performed in a total of 67 patients who had already undergone multiple treatment for abdominal-pelvic neoplasia with upper gastrointestinal obstruction, who could no longer be operated and who had a life expectancy of less than sixty days. In three cases positioning was not possible owing to the lack of transillumination of the gastric and abdominal wall. 54/64 patients had previously undergone at least two operations. RESULTS: Esophagogastric lesions were found in 29% of patients, some of which were attributed to the nasogastric tube. Symptomatic wellbeing was obtained in 76.5% a few days after PEG. PEG remained in situ from 4 to 472 days. Slight peristomal infection was observed in 9% of cases. In seven cases it was necessary to add octreotide owing to the reappearance of symptoms. CONCLUSIONS: PEG is relatively easy to use and allows obstructive symptoms to be resolved in the majority of patients. Special medical skills are not required and the patient may be easily managed at home together with support therapy and pain management. Once PEG has been performed, it is possible to take fluids and semi-liquid foods, offering the patient a chance to taste flavours which have often been forgotten. PEG enables neoadjuvant chemotherapy to be performed in patients with previously untreated intestinal obstruction. 相似文献
99.
经济利润率是评价一个实际热力装置的主要指标之一。将有限时间热力学,非平衡量子统计理论和yong经济学相结合,导出了量子斯特林制冷机的最大利润率以及对应的性能界限,其结果与实际斯特林制冷机的优化设计和模型评估提供了一个最佳的预选方案。 相似文献
100.
E Arvat R Giordano J Ramunni G Arnaldi A Colao R Deghenghi G Lombardi F Mantero F Camanni E Ghigo 《Canadian Metallurgical Quarterly》1998,83(12):4207-4211
We previously reported that in Cushing's disease (CD) the ACTH- and cortisol (F)-releasing activity of Hexarelin (HEX), a GH secretagogue, is exaggerated with respect to that in normal subjects and is higher than that of human CRH (hCRH), but it is absent in Cushing's syndrome. Our aim was to extend the study about the effects of HEX (2.0 microg/kg, iv) on ACTH and F secretion in 21 patients with CD (3 men and 18 women, 16-68 yr old). Based on magnetic resonance imaging, 15 CD patients had pituitary microadenoma, and 6 had macroadenoma. The results in CD patients were compared with those in 27 normal age-matched controls (NS; 10 men and 17 women, 24-69 yr old). Basal ACTH and F levels in CD were similar in patients with microadenom (mean+/-SEM, 78.3+/-7.2 pg/mL and 237.1+/-23.6 microg/L, respectively) and macroadenoma (57.4+/-9.0 pg/mL and 196.9+/-20.1 microg/L, respectively) and were higher (P < 0.001) than those in NS (17.7+/-2.0 pg/mL and 115.3+/-6.7 microg/L, respectively). In microadenoma CD patients, HEX induced marked ACTH and F increases (delta peak, mean+/-SEM: 261.2+/-77.6 pg/mL and 226.1+/-87.2 microg/L, respectively), which were higher (P < 0.04) than those induced by hCRH (45.6+/-16.9 pg/mL and 84.6+/-25.7 microg/L, respectively). Moreover, in microadenoma CD patients, the ACTH and F responses to HEX were higher (P < 0.001) than those in NS (18.5+/-4.0 pg/mL and 36.1+/-6.8 microg/L, respectively). In macroadenoma CD patients, HEX induced a slight, but significant increase (P < 0.02) in ACTH and F levels (33.9+/-18.0 pg/mL and 89.6+/-34.3 microg/L, respectively), which was not significantly different from that elicited by hCRH (20.0+/-7.0 pg/mL and 54.8+/-21.3 microg/L, respectively). In macroadenoma CD patients, the ACTH and F responses to HEX and hCRH were, in turn, similar to those in NS. In conclusion, our findings demonstrate that the ACTH and F hyperresponsiveness to HEX is present in Cushing's disease with micro-, but not macro- ACTH-secreting pituitary adenoma. This finding agrees with other evidence pointing toward differences in the hormonal behavior between micro- and ACTH-secreting pituitary macroadenomas. 相似文献