全文获取类型
收费全文 | 1217篇 |
免费 | 1篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 13篇 |
金属工艺 | 1篇 |
机械仪表 | 1篇 |
建筑科学 | 1篇 |
能源动力 | 1篇 |
轻工业 | 11篇 |
无线电 | 8篇 |
一般工业技术 | 6篇 |
冶金工业 | 1165篇 |
原子能技术 | 4篇 |
自动化技术 | 5篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2019年 | 1篇 |
2016年 | 3篇 |
2011年 | 1篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 3篇 |
2007年 | 3篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 40篇 |
1998年 | 373篇 |
1997年 | 201篇 |
1996年 | 120篇 |
1995年 | 70篇 |
1994年 | 63篇 |
1993年 | 57篇 |
1992年 | 5篇 |
1991年 | 17篇 |
1990年 | 13篇 |
1989年 | 17篇 |
1988年 | 22篇 |
1987年 | 13篇 |
1986年 | 16篇 |
1985年 | 12篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1980年 | 12篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 35篇 |
1976年 | 76篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 4篇 |
1971年 | 1篇 |
1959年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1218条查询结果,搜索用时 0 毫秒
1.
IG Sumner A Vaughan R Eisenthal RW Pickersgill AJ Owen PW Goodenough 《Canadian Metallurgical Quarterly》1993,1164(3):243-251
Papaya proteinase omega (pp omega) has been purified from dried latex both by immunoaffinity and traditional methods. Kinetic analysis revealed that (1), the pp omega-catalysed hydrolysis of N-benzoyl-L-arginine p-nitroanilide (BApNA) has a lower specificity (kcat/Km) than the same reaction catalysed by papain; (2), the pp omega-catalysed hydrolysis of a tripeptide substrate having phenylalanine at the second position (S2-site) showed a more similar specificity to that catalysed by papain; (3), the significant difference between the two enzymes is that steady state kinetics with both L-BApNA and a tripeptide enables the identification in pp omega of other ionizations affecting binding. The active sites of papain and pp omega can therefore be distinguished by pH-dependence of kcat/Km. 相似文献
2.
Renal length has been measured by ultrasound in 237 subjects with homozygous sickle cell (SS) disease, 147 with sickle cell-hemoglobin C (SC) disease, and in 78 age-matched controls with a normal hemoglobin (AA) genotype. As expected, renal length increased with age in all genotypes but mean length was significantly greater in SS disease compared with SC disease (mean difference 4.3 mm after adjustment for height) and significantly greater in both genotypes than in AA controls (SS/AA difference 9.2 mm, SC/AA difference 5.0 mm after adjustment for height). Examination of relationships between renal length and some hematological indices (hemoglobin, fetal hemoglobin, reticulocyte counts, alpha thalassemia status) in SS or SC disease showed only a significant negative correlation with hemoglobin and positive correlation with reticulocyte count in SS disease. Further analysis suggested that the stronger relationship was between renal length and high reticulocyte count. The mechanism of renal enlargement is unknown although glomerular hypertrophy and increased renal blood volume are likely contributors. 相似文献
3.
MP Armon SW Yusuf K Latief SC Whitaker RH Gregson PW Wenham BR Hopkinson 《Canadian Metallurgical Quarterly》1997,84(2):178-180
BACKGROUND: Aortic aneurysm anatomy is crucial when considering patients for endovascular repair. The aim of this study was to determine the proportion of patients with aortic aneurysm suitable for endovascular repair with three different graft-stent systems. METHODS: Spiral computed tomographic angiography was used to assess the anatomy of 154 abdominal aortic aneurysms. Measurements were made of aneurysm neck length and diameter, renal artery to aortic bifurcation length, common iliac artery diameter and length, and external iliac artery diameter. Aneurysms were assessed for anatomical suitability for currently available aortoaortic, aortobi-iliac and aortouni-iliac devices. RESULTS: Six patients (4 per cent) had a distal aortic neck suitable for implantation of a straight aortic graft. Fifteen patients (10 per cent) had arterial anatomy suitable for implantation of a bifurcated graft and 85 (55 per cent) patients were suitable for endovascular repair with an aortouni-iliac graft. The primary reasons for unsuitability were: proximal neck length less than 1.5 cm (44 patients), proximal neck diameter greater than 3.0 cm (12), and angulation of the proximal neck (three). A further ten patients were considered unsuitable for an aortouni-iliac graft because of bilateral common iliac artery aneurysms (four), tortuous iliac arteries (four) and narrow external iliac arteries (two). CONCLUSION: The aortouni-iliac device has the widest applicability of the currently available endovascular systems but open repair remains the only option for a large proportion of patients. 相似文献
4.
5.
The effectiveness of a combined regimen of mifepristone and vaginal misoprostol for termination of pregnancies of 9-13 weeks of gestation was investigated in 120 UK abortion patients (median age, 22.1 years; median duration of amenorrhea, 10.3 weeks). Each woman received a single oral dose of 200 mg of mifepristone 36-48 hours before admission, at which time 800 mcg of misoprostol was administered vaginally. Where indicated, a further two doses of 400 mcg of misoprostol (vaginal or oral) were provided every 3 hours. All 120 women aborted on the day of prostaglandin administration; however, 6 women (5%) required exploratory curettage after the procedure for retained placenta. The median prostaglandin dose was 1200 mcg (range, 800-1600 mcg). The median time from misoprostol administration to abortion was 4.33 hours (range, 1.3-16.0 hours). 60 women (50%) required oral analgesics and 26 (22%) received parenteral analgesia. Diarrhea occurred in 38 women (32%). The median duration of bleeding after abortion was 12.5 days (range, 3-43 days). In questionnaires administered to 73 women, only 3 (4%) expressed dissatisfaction with medical abortion, because of pain or prolonged bleeding. The relatively high dose of misoprostol used in this study and the vaginal route of administration are presumed to account for the 95% success rate. Extension of medical abortion to later gestation times would decrease the need for surgery and expand women's choice of methods of pregnancy termination. 相似文献
6.
7.
8.
HJ Berger KP van Spaendonck MW Horstink EL Buytenhuijs PW Lammers AR Cools 《Canadian Metallurgical Quarterly》1993,23(2):341-359
The pyrolytic behavior of inulin, a (2-->1)-linked fructofuranan, is described. Parallel investigations of the pyrolysis of glucose and of fructose were conducted to supplement the inulin results and to aid comparison with previous results from glucans. Effects of neutral and basic additives are emphasized. As with glucans, the addition of such additives (especially basic) increases the yields of the one-, two-, and three-carbon products (as well as of hexosaccharinolactones), while generally decreasing the yields of anhydro sugar and furan derivatives. The former products include glycolaldehyde, acetol, dihydroxy-acetone, acetic acid, formic acid, and lactic acid. Mechanistic speculations are made regarding the origins of these compounds, as well as of furan derivatives and saccharinic acid lactones. Parallels with alkaline degradation are considered. 相似文献
9.
10.