全文获取类型
收费全文 | 813篇 |
免费 | 12篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 24篇 |
化学工业 | 115篇 |
金属工艺 | 29篇 |
机械仪表 | 11篇 |
建筑科学 | 15篇 |
能源动力 | 61篇 |
轻工业 | 44篇 |
水利工程 | 3篇 |
无线电 | 52篇 |
一般工业技术 | 143篇 |
冶金工业 | 256篇 |
原子能技术 | 34篇 |
自动化技术 | 40篇 |
出版年
2023年 | 6篇 |
2021年 | 12篇 |
2020年 | 6篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 13篇 |
2016年 | 6篇 |
2015年 | 5篇 |
2014年 | 15篇 |
2013年 | 42篇 |
2012年 | 34篇 |
2011年 | 35篇 |
2010年 | 18篇 |
2009年 | 25篇 |
2008年 | 22篇 |
2007年 | 34篇 |
2006年 | 28篇 |
2005年 | 22篇 |
2004年 | 16篇 |
2003年 | 20篇 |
2002年 | 21篇 |
2001年 | 14篇 |
2000年 | 20篇 |
1999年 | 19篇 |
1998年 | 91篇 |
1997年 | 58篇 |
1996年 | 37篇 |
1995年 | 29篇 |
1994年 | 23篇 |
1993年 | 24篇 |
1992年 | 16篇 |
1991年 | 7篇 |
1990年 | 14篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 10篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 9篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有827条查询结果,搜索用时 374 毫秒
101.
Forehead recontouring in endoscopic surgery is presented. Eleven cases of protruded forehead deformity caused by benign tumor and one case of concave deformity caused by depressed frontal bone fracture were treated. All lesions were approached through incisions made in the hair-bearing area and operated on endoscopically. This method left no scars on the forehead, and the results were satisfactory. It is considered to be an excellent procedure with regard to cosmetic results. 相似文献
102.
Takuma Yamaguchi Minoru Maruyama Hidetoshi Miyao Yasuaki Nakano 《International Journal on Document Analysis and Recognition》2005,7(2-3):168-177
This paper proposes a method to recognize digits in a natural scene, such as telephone numbers on a signboard. Candidate regions of digits are extracted from an image through contrast enhancement, edge extraction, and labeling. Since the target text patterns are in a 3D space, unlike traditional character recognition problems, we have to deal with the image transformation effect due to the orientation in the 3D space and projection. We have to cancel the effect as much as possible before digit recognition. In our method, the image transformation effect is modeled as skew and slant. In the proposed method, simplified Hough transform is used for the skew normalization. After the skew normalization, the remaining effect of image transformation is corrected by circumscribing digit patterns with tilted rectangles and affine transformation. In experiments, we tested a total of 1,332 images of signboards with 11,939 digits. We obtained a digit extraction rate of 99.2% and a correct digit recognition rate of 98.8%.Received: 15 December 2003, Accepted: 21 October 2004, Published online: 2 February 2005 相似文献
103.
In Parkinson's disease the cell death of dopamine neurons has been proposed to be mediated by an apoptotic death process, in which nitric oxide may be involved. This article reports the induction of apoptosis by nitric oxide and peroxynitrite in human dopaminergic neuroblastoma SH-SY5Y cells and the antiapoptotic activity of (-)-deprenyl. After the cells were treated with a nitric oxide donor, NOR-4, or a peroxynitrite donor, SIN-1, DNA damage was quantitatively studied using a single-cell gel electrophoresis (comet) assay. NOR-4 and SIN-1 induced DNA damage dose-dependently. Cycloheximide and alkaline treatment of the cells prevented the DNA damage, indicating that the damage is apoptotic and that it depends on the intracellular signal transduction. Superoxide dismutase and the antioxidants reduced glutathione and alpha-tocopherol protected the cells from the DNA damage. (-)-Deprenyl protected the cells from the DNA damage induced by nitric oxide or peroxynitrite almost completely. The protection by (-)-deprenyl was significant even after it was washed from the cells, indicating that (-)-deprenyl may activate the intracellular system against apoptosis. These results suggest that (-)-deprenyl or related compounds may be neuroprotective to dopamine neurons through its antiapoptotic activity. 相似文献
104.
105.
The effect of direct electric current stress on the precipitation reaction in an Al-12.5 wt % Zn alloy was investigated by
the resistometric method. It was found that the d.c. stress retarded the reaction rate as in the case of an Al-4 wt% Cu alloy.
The dependence of the retarding effect on the annealing time and on the quenching temperature was examined on the basis of
a model of current-assisted vacancy annihilation. The annealing temperatures after quenching were 30 and 40° C, and the quenching
temperatures were varied from 300 to 500° C. 相似文献
106.
107.
N Goseki M Maruyama K Nagai F Kando M Endo K Shimoju Y Wada 《Canadian Metallurgical Quarterly》1995,22(8):1028-1035
Methionine-depleting total parenteral nutrition (Met-deplete TPN), infusing AO-90 amino acid solution (lacking both L-methionine and L-cysteine) as a sole nitrogen source, showed synergistic effects with several antineoplastics including 5-fluorouracil (5-FU). In the recent multi-center, randomized, controlled study, advanced gastric cancer patients were randomly allocated to RT group and Control group. RT group received AO-90 amino acid solution, while Control group infused Amiparen (commercial methionine and cysteine containing amino acid solution) as protein source for 14 days' TPN with 5-FU and mitomycin C (MMC). The over all clinical response rate (PR+CR) in RT and Control groups were 26.3% and 8.1%, respectively, with significant statistical difference in both values at p = 0.015. Fourteen advanced gastric cancer patients allocated to RT and Control group randomly and received each amino acid as protein source for 7 days TPN with 5-FU administration. All cases were performed gastrectomy without waiting period, and resected material was examined the histological response. In the 7 cases of RT group, grade 2 was seen in 4 cases, grade 1-b in 1, grade 1-a in 1 and grade 0 in 1. In the 7 of Control, 3 cases were grade 1-a and the remaining 4 were grade 0. There were significant differences in both degree and incidence of the histological response at p = 0.016. A stage IV gastric cancer patient with marked liver metastasis received 2 times RT therapy with 5-FU and MMC for 14 days and undertaken gastrectomy after 22 day, waiting period. Resected gastric cancer showed grade 2 to 3 histological response, and the liver metastasis showed marked effect as PR to CR. 相似文献
108.
Y Morita M Yamamura M Kawashima S Harada K Tsuji K Shibuya K Maruyama H Makino 《Canadian Metallurgical Quarterly》1998,41(9):1669-1676
BACKGROUND AND PURPOSE: To detect areas of cerebral perfusion from bypass arteries after vascular reconstruction, we administered selective intraarterial microsphere tracer into the external carotid arteries and determined (via single-photon emission computed tomography [IA-SPECT]) whether the distribution of radiotracer matched the arteriographic distribution of contrast material as shown on external carotid angiograms. METHODS: We compared the extent of regional distribution of tracer after external carotid artery injection of 20 to 40 MBq of 99mTc-HMPAO or 99mTc-ECD with that of contrast medium on the external carotid angiograms in 582 cortical regions in 12 patients with atherosclerotic occlusive disease and in 18 patients with moyamoya disease. RESULTS: Marked accumulation of tracer was found only in the expected, specific, newly developed areas of cerebral perfusion from bypass arteries. The regional distribution of tracer corresponded to that of contrast medium in 523 regions (90%) and did not correspond in 59 regions (10%). Significant overestimation of the distribution of contrast material relative to that of tracer was observed in the patients with moyamoya disease. CONCLUSION: SPECT showed slightly different distribution of tracer from that predicted by conventional angiography. IA-SPECT should enhance the analysis of newly developed areas of cerebral perfusion from the bypass arteries. 相似文献
109.
Carcinoma of the pancreas is a virulent malignancy. The purpose of this study was to evaluate the efficiency of 5-FU intraperitoneal administration for this malignancy. We developed a pancreatic cancer model whereby a human pancreatic cell line, MIA PaCa-2, was orthotopically transplanted to the pancreas of nude mice as cell suspension (1 x 10(6) cells). IP group (n = 6) received 5 times IP administration (4, 7, 12, 16, 20 days after implantation) of 5-FU 50 mg/kg, 1.5 ml. IV group (n = 6) received 5 times IV therapy (the same dates as IP group) of 5-FU 50 mg/kg, 0.2 ml. Control group (n = 6) received no treatment. The mice were sacrificed 42 days after implantation. The weight of the tumors of IP, IV and Control group was 0.332 +/- 0.143 g, 0.138 +/- 0.047 g and 0.329 +/- 0.085 g. Significant differences were found between IP and IV, and control. There was no difference between IP and control. This experiment demonstrated that 5 FUIP therapy for primary pancreatic cancer showed no effect and 5 FUIV therapy was much more effective. 相似文献
110.