全文获取类型
收费全文 | 3693篇 |
免费 | 148篇 |
国内免费 | 84篇 |
专业分类
电工技术 | 37篇 |
综合类 | 124篇 |
化学工业 | 146篇 |
金属工艺 | 120篇 |
机械仪表 | 80篇 |
建筑科学 | 245篇 |
矿业工程 | 36篇 |
能源动力 | 20篇 |
轻工业 | 102篇 |
水利工程 | 39篇 |
石油天然气 | 42篇 |
武器工业 | 24篇 |
无线电 | 119篇 |
一般工业技术 | 276篇 |
冶金工业 | 2377篇 |
原子能技术 | 29篇 |
自动化技术 | 109篇 |
出版年
2024年 | 19篇 |
2023年 | 24篇 |
2022年 | 50篇 |
2021年 | 52篇 |
2020年 | 38篇 |
2019年 | 42篇 |
2018年 | 43篇 |
2017年 | 40篇 |
2016年 | 31篇 |
2015年 | 46篇 |
2014年 | 51篇 |
2013年 | 83篇 |
2012年 | 83篇 |
2011年 | 84篇 |
2010年 | 73篇 |
2009年 | 77篇 |
2008年 | 69篇 |
2007年 | 90篇 |
2006年 | 107篇 |
2005年 | 74篇 |
2004年 | 60篇 |
2003年 | 57篇 |
2002年 | 53篇 |
2001年 | 32篇 |
2000年 | 34篇 |
1999年 | 100篇 |
1998年 | 699篇 |
1997年 | 437篇 |
1996年 | 276篇 |
1995年 | 160篇 |
1994年 | 141篇 |
1993年 | 185篇 |
1992年 | 30篇 |
1991年 | 31篇 |
1990年 | 32篇 |
1989年 | 39篇 |
1988年 | 23篇 |
1987年 | 27篇 |
1986年 | 20篇 |
1985年 | 20篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 13篇 |
1981年 | 12篇 |
1980年 | 17篇 |
1978年 | 7篇 |
1977年 | 64篇 |
1976年 | 137篇 |
1975年 | 10篇 |
1972年 | 6篇 |
排序方式: 共有3925条查询结果,搜索用时 15 毫秒
141.
142.
143.
The outdating of units of blood can be reduced by decreasing the amount of time they spend in an assigned or crossmatched status. This reduction can be achieved in a hospital by establishing a maximum surgical blood order schedule (MSBOS) which reduces the excessive number of units of blood crossmatched preoperatively for patients undergoing elective surgery. The various steps which occurred in the development of a MSBOS in a large general hospital are detailed and the projected reduction in the number of crossmatched units which can be achieved with the MSBOS is illustrated. illustrated. The projected number of units of blood transfused to patients during their hospitalization for 50 common primary surgical procedures in the United States during 1974 is presented as a basis for defining maximum blood orders for each procedure. 相似文献
144.
BA Lamberg 《Canadian Metallurgical Quarterly》1976,92(18):1008-1018
145.
146.
DP Stoker ML Perl G Abrams AR Baden T Barklow BA Barnett AM Boyarski J Boyer PR Burchat F Butler JM Dorfan GJ Feldman G Gidal G Hanson BD Harral K Hayes D Herrup JE Hylen WR Innes JA Jaros JA Kadyk D Karlen SR Klein AJ Lankford BW LeClaire M Levi V Lüth JA Matthews RA Ong K Riles PC Rowson DR Wood 《Canadian Metallurgical Quarterly》1989,39(7):1811-1824
147.
148.
149.
Association of risk factor variables and coronary artery disease documented with angiography 总被引:1,自引:0,他引:1
DR Holmes LR Elveback RL Frye BA Kottke RD Ellefson 《Canadian Metallurgical Quarterly》1981,63(2):293-299
Stepwise linear discrimination was used to analyze risk factors in 431 consecutive patients who underwent coronary angiography to determine which variables were most closely associated with coronary artery disease. Twenty-one risk factors were considered: total plasma cholesterol and triglycerides; the cholesterol and triglyceride content of high-density lipoproteins (HDL), low-density lipoproteins (LDL) and very low density lipoproteins (VLDL); and the percentage of total cholesterol and triglycerides in each fraction. Age, smoking history, family history, hypertension, diabetes mellitus and relative weight were also considered. Coronary artery disease was assessed using three standard grading scores. There were significant differences in risk factors between males and females. In males, LDL cholesterol and age were selected by multivariate analysis. In females, the ratio of HDL cholesterol to total cholesterol, as well as relative weight, family history, age and smoking were selected. The discriminating value of HDL cholesterol as the percentage of total cholesterol was significantly greater than that of HDL cholesterol itself. Despite highly significant associations between risk factors and the presence of coronary artery disease, the discrimination did not provide sufficient separation of the groups to give results that are useful diagnostically in individual patients. 相似文献
150.
Two hundred and seventy two children with the nephrotic syndrome were seen and followed up at the Paediatric Renal Unit of the University of Nigeria Teaching Hospital, Enugu over 12 1/2 year period, between June 1983 and December 1995. Of these, there were nine (3.3%) children with homozygous sickle cell disease (SS). This latter group had a mean age of 9.6 +/- 3.2 years, male to female ratio of 1:2 and serum cholesterol of 3.13 +/- 1.48 mmol/l at the time of diagnosis. The mortality rate was 55.6% in these sicklers, death occurring within one and a half to five years of diagnosis. Causes of death were attributable to sickle cell disease in 60%, renal diseases in 20%, and other causes in 20%. Renal biopsy in two of the sicklers showed membrano-proliferative glomerulonephritis (MPGN) and focal glomerulosclerosis (FGS) respectively. Homozygous sickle cell disease does seem to predispose to the development of the nephrotic syndrome and those that do develop nephrotic syndrome exhibit some special characteristics, when compared to non-sicklers with nephrotic syndrome. These include older age of onset of the nephrotic syndrome, reverse sex ratios, lower serum cholesterol, higher mortality rate and sickle cell complications rather than chronic renal failure as the major cause of death. 相似文献