全文获取类型
收费全文 | 3867篇 |
免费 | 32篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 19篇 |
综合类 | 2篇 |
化学工业 | 84篇 |
金属工艺 | 15篇 |
机械仪表 | 17篇 |
建筑科学 | 12篇 |
能源动力 | 8篇 |
轻工业 | 66篇 |
水利工程 | 4篇 |
石油天然气 | 4篇 |
无线电 | 31篇 |
一般工业技术 | 84篇 |
冶金工业 | 3497篇 |
原子能技术 | 1篇 |
自动化技术 | 63篇 |
出版年
2022年 | 8篇 |
2021年 | 20篇 |
2020年 | 13篇 |
2019年 | 12篇 |
2018年 | 21篇 |
2017年 | 16篇 |
2016年 | 19篇 |
2015年 | 9篇 |
2014年 | 18篇 |
2013年 | 27篇 |
2012年 | 20篇 |
2011年 | 36篇 |
2010年 | 25篇 |
2009年 | 16篇 |
2008年 | 16篇 |
2007年 | 17篇 |
2006年 | 12篇 |
2005年 | 16篇 |
2004年 | 8篇 |
2003年 | 14篇 |
2002年 | 5篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 102篇 |
1998年 | 1087篇 |
1997年 | 569篇 |
1996年 | 432篇 |
1995年 | 226篇 |
1994年 | 212篇 |
1993年 | 218篇 |
1992年 | 27篇 |
1991年 | 38篇 |
1990年 | 51篇 |
1989年 | 50篇 |
1988年 | 52篇 |
1987年 | 50篇 |
1986年 | 46篇 |
1985年 | 29篇 |
1984年 | 2篇 |
1983年 | 10篇 |
1982年 | 17篇 |
1981年 | 19篇 |
1980年 | 31篇 |
1979年 | 2篇 |
1978年 | 7篇 |
1977年 | 79篇 |
1976年 | 176篇 |
1975年 | 3篇 |
1972年 | 2篇 |
1955年 | 3篇 |
排序方式: 共有3907条查询结果,搜索用时 15 毫秒
1.
2.
Kinetic,thermodynamic parameters and in vitro digestion of tannase from Aspergillus tamarii URM 7115
Amanda Reges de Sena Tonny Cley Campos Leite Talita Camila Evaristo da Silva Nascimento Anna Carolina da Silva Catiane S. Souza Antônio Fernando de Mello Vaz 《Chemical Engineering Communications》2018,205(10):1415-1431
Tannase is an enzyme used in various industries and produced by a large number of microorganisms. The aim of this study was to evaluate tannase production to determine the biochemical, kinetic, and thermodynamic properties and to simulate tannase in vitro digestion. The tannase-producing fungal strain was isolated from “jamun” leaves and identified as Aspergillus tamarii. Temperature at 26°C for 67?h was the best combination for maximum tannase activity (6.35-fold; initial activity in Plackett–Burman design—15.53?U/mL and average final activity in Doehlert design—98.68?U/mL). The crude extract of tannase was optimally active at 40°C, pH 5.5 and 6.5. Moreover, tannase was stimulated by Na+, Ca2+, Mg2+, and Mn2+. The half-life at 40°C lasted 247.55?min. The free energy of Gibbs, enthalpy, and entropy, at 40°C, was 81.47, 16.85, and ?0.21?kJ/mol?·?K, respectively. After total digestion, 123.95% of the original activity was retained. Results suggested that tannase from A. tamarii URM 7115 is an enzyme of interest for industrial applications, such as gallic acid production, additive for feed industry, and for beverage manufacturing, due to its catalytic and thermodynamic properties. 相似文献
3.
PA Grace 《Canadian Metallurgical Quarterly》1997,166(3):152-156
PURPOSE: To examine the management and possible causes of primary valve malfunction of the Krupin eye valve with disk. METHODS: The authors reviewed the results of 113 patients undergoing implantation of the Krupin eye valve with disk and identified eight patients with primary valve malfunction requiring surgical revision. RESULTS: Valve revision involved manipulation (n = 1 case), explantation of the malfunctioning valve and implantation of a new valve (n = 2), and amputation of the valve (n = 5). Six of eight patients had final intraocular pressures of < 21 mmHg on one or no medications at a mean interval of 15.9 months (range 5-36) after surgical revision. Transient postoperative hypotony was noted in three patients and chronic hypotony with loss of light perception in one patient. One explanted valve was examined and found to have partially fused leaflets. CONCLUSIONS: Surgical revision in cases of primary valve malfunction of the Krupin eye valve with disk may be accomplished relatively safely with an acceptable level of postoperative complications. The etiology of primary valve malfunction may be related to the sterilization process and prolonged storage before implantation. 相似文献
4.
5.
6.
7.
KL Hopkins PK Dickson TI Ball RR Ricketts PA O'Shea CR Abramowsky 《Canadian Metallurgical Quarterly》1997,32(10):1476-1479
Fetus-in-fetu is an unusual condition in which a vertebrate fetus is enclosed within the abdomen of another fetus. These occurrences are usually benign. This report describes an instance of malignant recurrence after resection of a fetus-in-fetu. 相似文献
8.
The past year has seen significant advances in our understanding of the mechanism of RNA movement between the nucleus and the cytoplasm. The emerging view is that proteins bind to and escort RNAs to their proper subcellular location. The discovery of peptide signals that target nuclear export and the identification of novel protein mediators of RNA export are examples of significant recent discoveries. 相似文献
9.
10.
JP Heiner SS Kohles PA Manley R Vanderby MD Markel 《Canadian Metallurgical Quarterly》1997,(341):233-240
In a canine model, the fixation stability of a prosthesis and proximal bone graft composite were measured relative to the distal femur. One group had the prosthesis graft composite cemented into the distal femur. The second group had the prosthesis graft composite press fit into the distal femur for biologic ingrowth. Displacements of the proximal femoral grafts relative to the host bone in each group were measured after ex vivo (acute with graft) implantation and 4 months after implantation. A third group with no osteotomy (acute intact) simulated perfect graft to host bone union. Relative displacements representing 6 degrees freedom (translation and rotation) were calculated from the displacement values measured by 9 eddy current transducers. Measurements of displacement were used to test the hypothesis that distal press fit fixation equals distal cement fixation at 4 months after implantation. In all cases the measured translations and rotations of the graft to implant construct were small and of a magnitude that should encourage bone ingrowth (< 0.05 mm and < 0.1 degree, respectively). The stability of the press fit group at 4 months was not significantly different from the cemented group in axial and transverse displacement during axial and transverse loading, respectively. There was no difference in stabilities at 4 months between distal press fit and cemented fixation in hip replacements requiring a proximal femoral graft. 相似文献