全文获取类型
收费全文 | 4167篇 |
免费 | 0篇 |
专业分类
化学工业 | 15篇 |
建筑科学 | 2篇 |
轻工业 | 2篇 |
无线电 | 1篇 |
一般工业技术 | 4篇 |
冶金工业 | 4133篇 |
原子能技术 | 1篇 |
自动化技术 | 9篇 |
出版年
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 7篇 |
2012年 | 1篇 |
2010年 | 1篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2006年 | 2篇 |
2003年 | 6篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1999年 | 128篇 |
1998年 | 1287篇 |
1997年 | 710篇 |
1996年 | 461篇 |
1995年 | 266篇 |
1994年 | 191篇 |
1993年 | 260篇 |
1992年 | 42篇 |
1991年 | 48篇 |
1990年 | 45篇 |
1989年 | 71篇 |
1988年 | 60篇 |
1987年 | 64篇 |
1986年 | 42篇 |
1985年 | 49篇 |
1983年 | 9篇 |
1982年 | 17篇 |
1981年 | 29篇 |
1980年 | 27篇 |
1979年 | 2篇 |
1978年 | 6篇 |
1977年 | 110篇 |
1976年 | 210篇 |
1975年 | 6篇 |
1972年 | 1篇 |
1964年 | 1篇 |
1961年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有4167条查询结果,搜索用时 8 毫秒
31.
RA Malik S Tesfaye SD Thompson A Veves AK Sharma AJ Boulton JD Ward 《Canadian Metallurgical Quarterly》1993,36(5):454-459
Twenty diabetic patients with neuropathy underwent clinical and neurophysiological evaluation together with a detailed morphometric assessment of capillary pathology in endoneurial and epineurial microvascular beds of the sural nerve. Morphological data were compared with ten non-diabetic control subjects. There were no significant differences in control subjects between basement membrane area, endothelial cell area, endothelial cell profile number or luminal area of endoneurial when compared with epineurial capillaries. In contrast, when compared with epineurial capillaries, endoneurial capillaries from diabetic patients demonstrated a significant increase in basement membrane (p < 0.001) and endothelial cell (p < 0.001) area and a significant reduction in luminal area (p < 0.001). There was no significant difference in endothelial cell profile number between endoneurial and epineurial capillaries amongst diabetic patients. Previous studies have demonstrated a good correlation between the degree of microangiopathy and measures of neuropathic severity. In the present study increased endoneurial capillary basement membrane area was significantly related to reduced peroneal nerve conduction velocity (p < 0.001), myelinated fibre density (p < 0.001) and elevated vibration (p < 0.05) and thermal (p < 0.001) perception. Increased endothelial cell area and reduced luminal size were related to a reduced peroneal nerve conduction (p < 0.05, p < 0.01, respectively), reduced myelinated fibre density (p < 0.05, p < 0.01) and elevated thermal perception (p < 0.05, p < 0.001). Epineurial capillary basement membrane, endothelial cell and luminal area failed to relate to measures of neuropathic severity.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
32.
MH Thornton DB Johns JD Campeau F Hoehler GS DiZerega 《Canadian Metallurgical Quarterly》1998,13(6):1480-1485
The objective of this study was to assess the safety and to make a preliminary assessment of the efficacy of 0.5% ferric hyaluronate adhesion prevention gel in reducing adhesions in patients undergoing peritoneal cavity surgery by laparotomy, with a planned 'second-look' laparoscopy. The study was a randomized, open-label, placebo-controlled, parallel-group design in patients desirous of fertility at the Women's and Children's Hospital, Department of Obstetrics and Gynecology, University of Southern California School of Medicine, Los Angeles, California. Female patients aged 24 to 41 years received 300 ml 0.5% ferric hyaluronate adhesion prevention gel or lactated Ringer's solution as an intraperitoneal instillate at the completion of the laparotomy procedure. At second-look laparoscopy 4-12 weeks after the laparotomy, the presence of adhesions was evaluated. Haematology and serum chemistry were determined throughout the study interval. All patients tolerated the procedures well and did not manifest any serious adverse events. At second-look laparoscopy, patients treated with 0.5% ferric hyaluronate adhesion prevention gel had significantly fewer adhesions than control patients. When adhesions did form, they were significantly less extensive and less severe in patients who received 0.5% ferric hyaluronate adhesion prevention gel. In conclusion, 0.5% ferric hyaluronate adhesion prevention gel was safe and highly efficacious in the reduction of the number, severity and extent of adhesions throughout the entire abdomen following peritoneal cavity surgery. 相似文献
33.
34.
We present a case where a Wiktor intracoronary stent was inserted for 'poor angiographic result' following balloon angioplasty. Despite appropriate positioning and repeated dilation of the stent a suboptimal result was achieved because of plaque herniation through the stent. The case emphasizes that the choice of stent used is important and will become more so as the number of choices available increases. 相似文献
35.
36.
37.
JD Haag LA Shepel BD Kolman DM Monson ME Benton KT Watts JL Waller CC Lopez-Guajardo DJ Samuelson MN Gould 《Canadian Metallurgical Quarterly》2003,63(18):5808-5812
It has previously been shown that the Copenhagen (COP) rat contains several genetic loci that contribute to its mammary tumor-resistant phenotype after 7,12-dimethylbenz(a)anthracene (DMBA) administration. One of these loci, mammary carcinoma susceptibility 1 (Mcs1), is located on the centromeric end of chromosome 2 and appears to act in a semidominant fashion. To confirm the existence and independent action of this locus and also aid in the identification of the physical location of the Mcs1 gene, congenic lines were generated by transferring the Mcs1 COP allele onto a Wistar Furth (WF) genetic background. Male carriers were genotyped using microsatellite markers spanning 20-30 cM of the Mcs1 locus. One of the congenic lines minimally retained the COP allele at D2Mit29 on the centromeric end of chromosome 2 and extended distally to D2Rat201. Heterozygous Mcs1 carrier rats were interbred, and the female offspring were treated with DMBA. The female rats from the Mcs1 congenic line that carried one or two COP alleles of the Mcs1 region had a significantly reduced (65 and 85%, respectively) tumor development (P < 0.001) compared with rats carrying zero COP alleles at this locus. A WF.COP-D2Mit29/D2Rat201 homozygous congenic strain derived at the N10 generation was treated with DMBA, and the COP homozygous rats developed 1.5 +/- 0.3 carcinomas/rat versus 6.3 +/- 0.5 in WF control rats (P < 0.0001). Fine mapping of this congenic interval using several recombinant lines identified three genetic loci within the Mcs1 congenic region that independently supported a tumor resistance phenotype. These genetic loci have been termed Mcs1a, Mcs1b, and Mcs1c. In rats for which each locus was homozygous for the COP allele, tumor development was reduced by approximately 60% compared with littermate controls. The identification of these independent loci within the Mcs1 COP allele provide a model of the genetic complexity of cancer. 相似文献
38.
39.
The specification of vowel formant bandwidths for speech synthesis has been inconsistent in the past, perhaps due to the difficulty of measuring formant bandwidths in natural speech and the possible perceptual insignificance of formant bandwidths on the intelligibility of synthetic speech. Here, regression equations are presented for the estimation of formant bandwidths based on measurements from natural speech which is based only on formant center frequency and independent of other formant values. Current usage, as well as comparison with another well-known estimation algorithm suggests that the new procedure should be quite acceptable for some types of speech synthesis. 相似文献
40.
JD Adachi WG Bensen F Bianchi A Cividino S Pillersdorf RJ Sebaldt P Tugwell M Gordon M Steele C Webber CH Goldsmith 《Canadian Metallurgical Quarterly》1996,23(6):995-1000
OBJECTIVE: To determine the efficacy and safety of vitamin D 50,000 units/week and calcium 1,000 mg/day in the prevention of corticosteroid induced osteoporosis. METHODS: A minimized double blind, placebo controlled trial in corticosteroid treated subjects in a tertiary care university affiliated hospital. The sample was 62 subjects with polymyalgia rheumatica, temporal arteritis, asthma, vasculitis, or systemic lupus erythematosus. The primary outcome measure was the percentage change in bone mineral density (BMD) of the lumbar spine in the 2 treatment groups from baseline to 36 mo followup. RESULTS: BMD of the lumbar spine in the vitamin D and calcium treated group decreased by a mean (SD) of 2.6% (4.1%) at 12 mo, 3.7% (4.5%) at 24 mo, and 2.2% (5.8%) at 36 mo. In the placebo group there was a decrease of 4.1% (4.1%) at 12 mo, 3.8% (5.6%) at 24 mo, and 1.5% (8.8%) at 36 mo. The observed differences between groups were not statistically significant. The difference at 36 mo was-0.693% (95% CI -5.34, 3.95). CONCLUSION: Vitamin D and calcium may help prevent the early loss of bone seen in the lumbar spine as measured by densitometry of the lumbar spine. Longterm vitamin D and calcium in those undergoing extended therapy with corticosteroids does not appear to be beneficial. 相似文献