全文获取类型
收费全文 | 5523篇 |
免费 | 16篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 11篇 |
化学工业 | 105篇 |
金属工艺 | 26篇 |
机械仪表 | 11篇 |
建筑科学 | 33篇 |
矿业工程 | 2篇 |
能源动力 | 9篇 |
轻工业 | 119篇 |
水利工程 | 10篇 |
石油天然气 | 10篇 |
无线电 | 96篇 |
一般工业技术 | 154篇 |
冶金工业 | 4853篇 |
原子能技术 | 5篇 |
自动化技术 | 98篇 |
出版年
2022年 | 6篇 |
2021年 | 6篇 |
2019年 | 8篇 |
2018年 | 11篇 |
2017年 | 9篇 |
2016年 | 8篇 |
2015年 | 4篇 |
2014年 | 19篇 |
2013年 | 40篇 |
2012年 | 31篇 |
2011年 | 46篇 |
2010年 | 29篇 |
2009年 | 28篇 |
2008年 | 29篇 |
2007年 | 34篇 |
2006年 | 30篇 |
2005年 | 29篇 |
2004年 | 17篇 |
2003年 | 33篇 |
2002年 | 20篇 |
2001年 | 14篇 |
2000年 | 23篇 |
1999年 | 176篇 |
1998年 | 1457篇 |
1997年 | 799篇 |
1996年 | 544篇 |
1995年 | 291篇 |
1994年 | 254篇 |
1993年 | 278篇 |
1992年 | 50篇 |
1991年 | 84篇 |
1990年 | 70篇 |
1989年 | 99篇 |
1988年 | 84篇 |
1987年 | 72篇 |
1986年 | 85篇 |
1985年 | 65篇 |
1984年 | 19篇 |
1983年 | 21篇 |
1982年 | 22篇 |
1981年 | 35篇 |
1980年 | 57篇 |
1979年 | 10篇 |
1978年 | 16篇 |
1977年 | 132篇 |
1976年 | 282篇 |
1975年 | 11篇 |
1974年 | 7篇 |
1973年 | 9篇 |
1918年 | 3篇 |
排序方式: 共有5542条查询结果,搜索用时 16 毫秒
991.
992.
JE Gj?res 《Canadian Metallurgical Quarterly》1977,92(6-7):162-163
993.
JE Bazin B Dureuil G Danialou E Vicaut M Aubier JM Desmonts J Boczkowski 《Canadian Metallurgical Quarterly》1998,81(3):430-435
We have assessed, by intravital microscopy in rats, the effects of different anaesthetics on diaphragmatic arteriolar diameter. Rats were anaesthetized with etomidate, propofol or thiopental (groups E, P and T, respectively) and the diameters of the arterioles were measured sequentially at baseline and after topical application of either mefenamic acid (MA, 20 mumol litre-1) or N omega-nitro-L-arginine (NNA, 300 mumol litre-1), inhibitors of prostaglandins and nitric oxide, respectively. In group E, baseline arteriolar diameters were significantly higher than those in the two other groups (P < 0.01). MA and NNA induced significant constriction in the three groups (P < 0.001). However, whereas constriction induced by NNA was similar in the three groups, constriction induced by MA was significantly higher in group E compared with groups P and T (P < 0.05). We conclude that diaphragmatic arteriolar diameters in rats were greater during etomidate than during thiopental or propofol anaesthesia. This phenomenon may be mediated by prostaglandins. 相似文献
994.
JE Nielsen 《Canadian Metallurgical Quarterly》1998,160(23):3393-3397
Skin symptoms on the hands were studied in questionnaire-based studies conducted in 1989 and 1991 among female cleaners employed at Danish nursing homes, schools and offices. Eleven hundred and sixty-six participated in 1989 and 1011 of them participated in 1991. The average age was 45 years and the average length of five employed as a cleaner was ten years. Forty-three percent reported to have had at least one out of four skin symptoms during a one year period. Seventy percent reported improvement during week-ends and holidays. A positive correlation was found between hours per week spent with wet hands and skin symptoms. During the follow-up period the risk of developing skin symptoms was higher in the group who remained cleaners compared with the group who left the cleaning job. Similarly, the prognosis was better in the group which left the cleaning job compared with the group which remained cleaners. There is a future need to develop and implement new work organisation and cleaning methods to reduce the time spent with wet hands. 相似文献
995.
JE Thole B Wieles JE Clark-Curtiss TH Ottenhoff TF Rinke de Wit 《Canadian Metallurgical Quarterly》1995,18(5):791-800
A major focus of leprosy research in the last 10 years has been the identification and characterization of antigens of Mycobacterium leprae that interact with antibodies and T cells of the host's immune response. Through the combined efforts of many different laboratories, a substantial number of protein antigens have been identified and characterized. In this MicroReview we present an updated list of M. leprae protein antigens, and, with emphasis on recent developments, summarize what is known regarding their functional and immunological features. 相似文献
996.
Open reduction and internal fixation has become the standard of care for the treatment of most displaced acetabular fractures. As surgical techniques have become refined, long term results of surgical fixation have improved. During the past 10 to 15 years, several controversies have surfaced in the orthopaedic literature regarding the treatment of acetabular fractures. The recent literature regarding acetabular fixation was reviewed. Controversies include the most efficacious surgical approach for complex acetabular fractures; the effectiveness of intraoperative sciatic nerve monitoring; the most effective method of prophylaxis against deep vein thrombosis; and the indications for and method of prophylaxis against heterotopic bone formation. 相似文献
997.
998.
Bullous pemphigoid (BP) blisters contain several molecules, some of which spread into the blisters from the interstitial fluid, while others are produced locally and migrate into the circulation. The calculation of the ratios between blister/serum concentrations may help to distinguish between these two types of molecules. The rules regulating the diffusion of the molecules have been described only in suction blisters, where the theoretical molecular weight (MW) represents one of the principal influencing factors. The aim of the present study was to analyse the relationship between theoretical MWs and the ratios of concentrations of several molecules evaluated both in sera and in blister fluids. Eight cytokines (interleukin-2, interleukin-3, interleukin-4, interleukin-5, interleukin-10, tumor necrosis factor-alpha, oncostatin-M and vascular endothelial growth factor), two acute phase reactants (alpha-1 acid glycoprotein, haptoglobin), albumin, one soluble membrane molecule with adhesion functions (sICAM-1) and the eosinophil cathionic protein (ECP) were measured in samples from 15 patients affected with BP by means of commercially available tests. The data suggest that the MW may influence the rate of diffusion throughout the blister, both in input and output directions, despite the discontinuity observed at the basement membrane level on the BP blister floor. 相似文献
999.
1000.
W Chalupa B Vecchiarelli DT Galligan JD Ferguson LS Baird RW Hemken RJ Harmon CG Soderholm DE Otterby RJ Annexstad JG Linn WP Hansen FR Ehle DL Palmquist RG Eggert 《Canadian Metallurgical Quarterly》1996,79(5):800-812
Beginning at wk 5 of lactation, 136 cows (34 per treatment) were supplemented daily for 38 wk with 0, 10.3, 20.6, or 41.2 mg of recombinantly derived bST monomer. Cows were obtained from University of Kentucky, University of Minnesota, University of Pennsylvania, and The Ohio State University. Nine cows (4 at 0 mg/d, 1 at 10.3 mg/d, 1 at 20.6 mg/d, and 3 at 41.2 mg/d) did not complete the experiment because of health problems. Data from these cows were included in the reproduction and health databases but not in the production database. Cows supplemented with bST produced more milk, consumed more feed, had lower rates of BW gain, and had improved efficiencies of milk production (conversion of feed and NEL to milk). Additional increases in productivity were modest at 20.6 and 41.2 mg/d versus productivity at 10.3 mg/d of bST. Concentrations of fat, protein, and TS in milk were unaffected. At 10.3 mg/d, bST did not adversely affect reproduction or health. 相似文献