全文获取类型
收费全文 | 8770篇 |
免费 | 188篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 58篇 |
综合类 | 5篇 |
化学工业 | 1050篇 |
金属工艺 | 116篇 |
机械仪表 | 75篇 |
建筑科学 | 217篇 |
矿业工程 | 4篇 |
能源动力 | 89篇 |
轻工业 | 542篇 |
水利工程 | 31篇 |
石油天然气 | 8篇 |
武器工业 | 1篇 |
无线电 | 379篇 |
一般工业技术 | 907篇 |
冶金工业 | 4975篇 |
原子能技术 | 58篇 |
自动化技术 | 444篇 |
出版年
2022年 | 33篇 |
2021年 | 64篇 |
2020年 | 46篇 |
2019年 | 50篇 |
2018年 | 76篇 |
2017年 | 75篇 |
2016年 | 101篇 |
2015年 | 100篇 |
2014年 | 114篇 |
2013年 | 163篇 |
2012年 | 159篇 |
2011年 | 190篇 |
2010年 | 183篇 |
2009年 | 147篇 |
2008年 | 179篇 |
2007年 | 148篇 |
2006年 | 159篇 |
2005年 | 115篇 |
2004年 | 121篇 |
2003年 | 134篇 |
2002年 | 108篇 |
2001年 | 126篇 |
2000年 | 112篇 |
1999年 | 241篇 |
1998年 | 1613篇 |
1997年 | 977篇 |
1996年 | 646篇 |
1995年 | 340篇 |
1994年 | 259篇 |
1993年 | 315篇 |
1992年 | 78篇 |
1991年 | 93篇 |
1990年 | 105篇 |
1989年 | 96篇 |
1988年 | 81篇 |
1987年 | 74篇 |
1986年 | 83篇 |
1985年 | 65篇 |
1984年 | 37篇 |
1983年 | 47篇 |
1982年 | 56篇 |
1981年 | 53篇 |
1980年 | 68篇 |
1979年 | 48篇 |
1978年 | 45篇 |
1977年 | 156篇 |
1976年 | 273篇 |
1975年 | 39篇 |
1970年 | 27篇 |
1966年 | 26篇 |
排序方式: 共有8959条查询结果,搜索用时 15 毫秒
141.
John S. Wright Joseph M. Schwartz Lanny D. Schmidt Lorraine Falter Francis 《Journal of the American Ceramic Society》1995,78(9):2360-2366
The crystalline phase development and microstructural changes with heating of sol-gel-derived lead titanate (PT) particles and films on silica with and without a fugitive (or removable) diffusion barrier layer were investigated. Amorphous gel-derived PT particles were deposited on SiO2 -coated TEM grids with and without polyimide (PI) or carbon barrier layers between SiO2 and PT. TEM analysis showed that PI or carbon barriers prevented reaction between the gel-derived PT particles and SiO2 . PT particles crystallize and then the PI or carbon film decomposes. Sol-gel-derived PT films were deposited on oxidized Si substrates (Si/SiO2 ) with and without a PI barrier layer. Perovskite PT films were prepared on Si/SiO2 substrates with a PI barrier; however, some porosity remained in the films. Identically prepared films without the PI barrier formed a mixture of pyrochlore and perovskite. X-ray photoelectron spectroscopy results indicate that the PI film pre- vents the diffusion of Si into the PT film. 相似文献
142.
J Schmidt 《Canadian Metallurgical Quarterly》1996,14(1):10-13
Toothbrush contamination during the procedure of brushing was assessed at different time intervals of usage. A peak value of 100% contamination was found at 1 month interval. Hence, a method suggesting disinfection of the toothbrush was employed by comparing the effectiveness of various disinfecting solutions available in the market so that, the brush does not become a source of potential pathogens. 相似文献
143.
144.
145.
KS Elenitoba-Johnson ML Eberhard RM Dauphinais PJ Lammie J Khorsand 《Canadian Metallurgical Quarterly》1996,105(4):384-387
Human infection with a zoonotic Brugia species in the United States is uncommon. Positive identification of the filarial nematode is required for histopathologic diagnosis. Many cases may go unrecognized because of the nonspecific clinical manifestations and the nondiagnostic histologic changes occurring in involved lymph nodes. A case of zoonotic Brugia lymphadenitis is described in a patient from Rhode Island, in which a small nongravid female worm was identified in a lymph node biopsy specimen. The lymph node also showed a spectrum of reaction changes including the presence of florid monocytoid B-cell proliferation, which has not been described in association with zoonotic Brugian filariasis. 相似文献
146.
147.
As part of an 18-month carcinogenicity study, 680 Syrian hamsters (Mesocricetus auratus) received daily gavage doses of fenazaquin, an experimental miticide. Mortality associated with severe enteritis was noticed beginning when the hamsters were 4 months old and ranged from one to five deaths per month until the hamsters were about 10 months old, when 41 deaths occurred in a 1-month period. Ante- and postmortem findings were consistent with those reported for antibiotic-induced enteritis in hamsters. Clostridium difficile was isolated from 12 of the 13 samples of cecal contents analyzed. Toxin assays of C. difficile isolates collected from 11 affected animals were positive for both cyto- and enterotoxins. Daily oral administration of vancomycin hydrochloride at a dose of 20 mg/kg was initiated when the hamsters were about 10 months old. Deaths due to C. difficile enteritis were significantly decreased within 2 weeks, and treatment was continued for 3 months. A trial withdrawal period for a subset of 64 hamsters (approximately 16% of the total population) was initiated to evaluate survival after discontinuation of the antibiotic treatment. Clostridium difficile enteritis recurred within 2 weeks and caused 19 deaths during the next month; therefore, these hamsters were returned to daily vancomycin treatment for the remainder of the study. With the exception of severe gaseous distention of the ceca, which caused death in 17 (< 4% of the total population) of the affected hamsters, vancomycin treatment did not cause any major adverse effects.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
148.
JM Chen ML Barr A Chadburn G Frizzera FA Schenkel RR Sciacca DS Reison LJ Addonizio EA Rose DM Knowles 《Canadian Metallurgical Quarterly》1993,56(3):527-538
We conducted a retrospective study of 516 cardiac recipients who underwent transplantation between April 1983 and April 1992, 19 of whom had development of post-transplantation lymphoproliferative disorders (PTLDs). These 19 patients presented with involvement of lung (5), gastrointestinal tract (5), disseminated disease (6), and adenoids and lymph nodes (3). B-cell proliferations ranging from an atypical hyperplasia to malignant lymphoma developed in 18 patients, and mixed cellularity Hodgkin's disease developed in 1 patient. The 19 patients with PTLD displayed a predominance of both women and cardiomyopathy as the indication for transplantation when compared with two separate control populations. No correlation was found between demographic criteria analyzed and (1) early versus late diagnosis of PTLD after transplantation, (2) the site of PTLD involvement, or (3) the histopathologic category of the PTLD lesion. Patients with gastrointestinal tract and lung PTLD involvement enjoyed an improved survival after both transplantation and PTLD diagnosis when compared with patients with PTLD involvement of all other extranodal sites. We report a high incidence of PTLD involving the lung and gastrointestinal tract in our cohort study. These sites of involvement responded better to a reduction in immunosuppression than did the other extranodal sites of involvement. 相似文献
149.
150.
S. Langenbuch J. Hadek K.-D. Schmidt K. Velkov 《Progress in Nuclear Energy》2006,48(8):912-1Benchmark
The VVER-1000 Coolant Transient Benchmark consists of two phases and refers to experimental data from the Kozloduy Unit 6 Nuclear Power Plant in Bulgaria. The paper describes the modelling features and their impact on the results of the Exercise 1, Phase 1 of the Benchmark obtained by two ATHLET user groups, namely GRS and NRI. The simulated transient is a main coolant pump (MCP) switching on in one loop at reduced power while three other MCPs are in operation. Particular attention is paid to the influence of the reactor vessel modelling and especially of the nodalization in the upper plenum. The comparison and discussion of the two simulation results confirm that the two solutions with the ATHLET system code achieve quite good system response of the plant transient. 相似文献