全文获取类型
收费全文 | 621篇 |
免费 | 1篇 |
专业分类
电工技术 | 1篇 |
综合类 | 1篇 |
化学工业 | 4篇 |
金属工艺 | 1篇 |
机械仪表 | 5篇 |
矿业工程 | 2篇 |
能源动力 | 2篇 |
轻工业 | 4篇 |
水利工程 | 1篇 |
无线电 | 1篇 |
一般工业技术 | 18篇 |
冶金工业 | 569篇 |
原子能技术 | 1篇 |
自动化技术 | 12篇 |
出版年
2021年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2013年 | 1篇 |
2012年 | 3篇 |
2011年 | 4篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 2篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 16篇 |
1998年 | 164篇 |
1997年 | 93篇 |
1996年 | 70篇 |
1995年 | 38篇 |
1994年 | 25篇 |
1993年 | 31篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 10篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 6篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 18篇 |
1976年 | 38篇 |
1975年 | 2篇 |
1955年 | 2篇 |
1943年 | 2篇 |
1940年 | 1篇 |
排序方式: 共有622条查询结果,搜索用时 15 毫秒
81.
TC Jarvis LJ Alby AA Beaudry FE Wincott L Beigelman JA McSwiggen N Usman DT Stinchcomb 《Canadian Metallurgical Quarterly》1996,2(5):419-428
Proliferation of injured smooth muscle cells contributes to the reocclusion or restenosis of coronary arteries that often occurs following angioplasty procedures. We have identified and optimized nuclease-resistant ribozymes that efficiently cleave c-myb RNA. Three ribozymes targeting different sites in the c-myb mRNA were synthesized chemically and delivered to rat aortic smooth muscle cells with cationic lipids; all three inhibited serum-stimulated cell proliferation significantly. RNA molecules with two base substitutions in the catalytic core that render the ribozyme catalytically inactive had little effect on smooth muscle cell proliferation. Ribozymes with scrambled binding arm sequences also failed to affect cell cycle progression of vascular smooth muscle cells. Furthermore, inhibition of rat smooth muscle cell proliferation correlated with a reduction in intact c-myb mRNA. Efficacy of the chemically-modified ribozyme was compared directly to phosphorothioate antisense oligodeoxynucleotides targeting the same site in the c-myb RNA; the ribozyme had superior efficacy and showed greater specificity than the antisense molecules. Exogenously delivered ribozymes also inhibited porcine and human smooth muscle cell proliferation effectively. Ribozymes targeting c-myb or other regulators of smooth muscle cell proliferation may represent novel therapeutics for the treatment of restenosis after coronary angioplasty. 相似文献
82.
FF Cox WJ Morshuis HW Plokker JC Kelder HA van Swieten A Brutel de la Rivière PJ Knaepen FE Vermeulen 《Canadian Metallurgical Quarterly》1996,61(6):1752-7; discussion 1757-8
BACKGROUND: The aim of this study was to identify factors influencing early outcome after surgical treatment of postinfarction ventricular septal rupture. We investigated the influence of proximal or distal rupture location. METHODS: Between 1980 and 1992 109 patients were treated surgically for ventricular septal rupture using a standardized technique. A division in time periods was made. The rupture was categorized according to its anterior or posterior site and proximal or distal location. RESULTS: The 30-day mortality rate was 27.5%. Multivariate logistic regression analysis identified preoperative shock (p = 0.0007) and right atrial oxygen saturation less than 60% (p = 0.021) as predictors for early death; the risk for early death declined over the time periods from 50% to 12.8% (p = 0.0007). Proximal ventricular septal rupture location (p = 0.0092) and interval between infarction and ventricular septal rupture less then 1 day (p = 0.034) were risk factors for the occurrence of preoperative shock. CONCLUSIONS: Proximal ventricular septal rupture location was the main determinant of preoperative cardiogenic shock, which in turn was the strongest predictor of early mortality. Over the time periods a decrease in early mortality was reached. 相似文献
83.
IB Natvig FE Johansen TW Nordeng G Haraldsen P Brandtzaeg 《Canadian Metallurgical Quarterly》1997,159(9):4330-4340
Transport of polymeric Igs (pIgA and pIgM) across secretory epithelia is mediated by the polymeric Ig receptor (pIgR), also known as the transmembrane secretory component. Compared with local production, external transfer of pIgA is favored 6- to 12-fold over that of pIgM on a molar basis. This transfer may be modulated at several levels: diffusion through matrix and basement membranes, ligand affinity for pIgR, and efficiency of epithelial transcytosis. To investigate these possibilities, we compared the ability of Madin-Darby canine kidney epithelial cells transfected with human pIgR to transport pIgA vs pIgM from the basolateral to the apical face, and examined the inhibitory effect of various filter types used for mounting of the monolayer. Binding data showed that pIgR bound pIgA and pIgM with similar affinity. Internalization of both ligands was fast and took place at similar rates; transcytosis was also found to be equally efficient at the molar level. Thus, the overall rate of transport across the epithelial monolayer was comparable for pIgA and pIgM, and was not further enhanced by ligand stimulation over a 20-fold increased concentration level. Conversely, pIgA had a considerable advantage over pIgM in passive diffusion assays performed in vitro. Moreover, in situ immunofluorescence staining showed retention of IgM over IgA and IgG in mucosal basement membrane zones, in contrast to the preferential epithelial uptake of IgA and, less so, IgM. The biologic consequences of the highly efficient epithelial pIg transport, and the diffusion advantage of pIgA over pIgM, are discussed in relation to the evolution and function of secretory Abs. 相似文献
84.
CC Gallen E Tecoma V Iragui DF Sobel BJ Schwartz FE Bloom 《Canadian Metallurgical Quarterly》1997,38(4):452-460
PURPOSE: Regional cortical dysfunction associated with epileptogenic activity was predicted from interictal localized abnormal low frequency neuromagnetic activity (ALFMA) using Magnetic Source Imaging (MSI). ALFMA can be detected in patients who show no interictal spikes. METHODS: A large array biomagnetometer was used in a blinded, rapid screening protocol. The MSI procedure required no alteration in epileptic medications. MSI results were compared with the presumed epileptogenic region as determined by a consensus of standard techniques, which included MR and electroclinical monitoring. RESULTS: One or more sites of localized abnormality were detected by MSI ALFMA in 29 of the 33 epileptic patients. ALFMA mapped with MSI showed a 48.5% specificity with respect to the presumed epileptogenic region. MSI ALFMA was in agreement with the final consensus as often as was ictal noninvasive video EEG monitoring, and was exceeded in specificity overall only by invasive ictal video EEG monitoring, which was required for conventional localization in 21 of the 33 patients tested with MSI. CONCLUSIONS: ALFMA measurements with MSI may augment the array of noninvasive methods used for reaching a consensus for epilepsy surgery. 相似文献
85.
SS Huang Q Liu FE Johnson Y Konish JS Huang 《Canadian Metallurgical Quarterly》1997,272(43):27155-27159
Transforming growth factor beta (TGF-beta) has been implicated in the pathogenesis of various human diseases. Synthetic TGF-beta antagonists therefore could have therapeutic utility. Here we show the development of such compounds. Three synthetic pentacosapeptides designated beta125-(41-65), beta225-(41-65), and beta325-(41-65), whose amino acid sequences correspond to the 41st to 65th amino acid residues of TGF-beta1, TGF-beta2, and TGF-beta3, respectively, inhibit the binding of 125I-labeled TGF-beta isoforms to TGF-beta receptors in mink lung epithelial cells with IC50 of approximately 0.06-2 microM. beta125-(41-65) blocks TGF-beta1-induced growth inhibition and TGF-beta1-induced plasminogen activator inhibitor-1 expression in these cells. The variants designated beta125-(41-65)W52A/D55A and beta325-(41-65)R52A/D55A, in which both Trp52/Arg52 and Asp55 are replaced by alanine residues, do not have TGF-beta antagonist activity. Multiple conjugation of beta125-(41-65) to carrier proteins enhances its antagonist activity but also confers partial agonist activity as measured by DNA synthesis inhibition. These results suggest that the (W/R)XXD motif is important for the activities of these TGF-beta peptide antagonists and that this motif may be the active site sequence of TGF-beta. 相似文献
86.
FI Raynaud FE Boxall PM Goddard M Valenti M Jones BA Murrer M Abrams LR Kelland 《Canadian Metallurgical Quarterly》1997,3(11):2063-2074
A novel sterically hindered platinum complex, AMD473 [cis-amminedichloro(2-methylpyridine) platinum(II)], designed primarily to be less susceptible to inactivation by thiols, has shown in vitro activity against several ovarian carcinoma cell lines. Notably, AMD473 has shown activity in vitro in human carcinoma cells that have acquired cisplatin resistance due to reduced drug transport (41M/41McisR) or enhanced DNA repair/increased tolerance of platinum-DNA adducts (CH1/CH1cisR). In this study, we show that AMD473, at its maximum tolerated dose of 35-40 mg/kg i.p. administration, produced marked in vivo antitumor activity against a variety of murine (ADJ/PC6 plasmacytoma, L1210 leukemia) and human ovarian carcinoma xenograft models, including several possessing acquired resistance to cisplatin [ADJ/PC6cisR, L1210cisR, CH1cisR, and HX110 (carboplatin-resistant)]. In the ADJ/PC6 model, an increased therapeutic index was noted following oral as opposed to i. p. administration. In a head-to-head comparison using CH1cisR xenografts and equitoxic doses (q7dx4 schedule), comparative growth delays were as follows: AMD473, 34 days; cisplatin, 10.4 days; carboplatin, 6.4 days; and JM216 (p.o. administration), 3.5 days (in a previous experiment, the trans-platinum complex JM335 induced a growth delay of 5.4 days against this model). In this model, oral activity was also noted with a growth delay of 34 days at 400 mg/kg every 7 days (total of four doses). In addition, AMD473 showed promising activity against CH1 xenografts that had regrown following initial treatment with cisplatin (additional growth delay of 30 days over that observed for retreatment with cisplatin). Across the whole panel of cisplatin-sensitive to cisplatin-resistant human ovarian carcinoma xenografts, AMD473 showed improved or at least comparable activity to that observed for an equitoxic dose (4 mg/kg) and schedule of cisplatin. Platinum pharmacokinetics showed that following i.v. administration of 20 mg/kg AMD473 in saline to Balb/c- mice bearing murine plasmacytoma (ADJ/PC6), a biexponential decay was observed in the plasma with a rapid distribution t1/2alpha of 24 min followed by a slow elimination t1/2beta of 44 h. Platinum accumulated in various organs with platinum tissue to plasma area under the curve ratios of 8.6 for liver and kidney, 5.7 for spleen, 3.7 for heart, 5.2 for lung, and 5 for tumor. The plasma and tissue concentration time curve following i.p. administration was similar to that observed following i.v. administration, with a bioavailability of 89%. When AMD473 was given p.o., the platinum absorption was rapid (K01 of 30 min) and the bioavailability was 40%. A less than proportional increase in area under the curve and Cmax was noted in tissue, plasma, and plasma ultrafiltrate following increasing oral doses of AMD473. In vitro, with AMD473, the rate of binding to different plasma proteins was approximately half of that of cisplatin. Following administration of 45 mg/kg i.p. in oil, 33% of the administered platinum was eliminated in the urine after 24 h, and 40% was eliminated after 72 h. Fecal recovery represented 13% of the administered dose after 3 days. Similar results were observed following oral and i.v. administration of 20 mg/kg, but significantly more was excreted in the feces (over 50% of the administered dose) following oral administration of 400 mg/kg, showing that absorption might be a limiting factor by this route of administration. The dose-limiting toxicity for AMD473 in mice was myelosuppression, and no renal toxicity was observed. The promising antitumor activity of AMD473, together with its lack of nephrotoxicity and favorable pharmacokinetic profile, suggests that AMD473 is a good candidate for clinical development. AMD473 is entering Phase I clinical trials under the auspices of the United Kingdom Cancer Research Campaign in 1997. 相似文献
87.
FF Cox WJ Morshuis JC Kelder HW Plokker HJ Langemeijer FE Vermeulen 《Canadian Metallurgical Quarterly》1996,10(9):748-753
OBJECTIVES: The aim of this study was to identify factors causing rupture recurrence after surgical repair of postinfarction ventricular septal rupture and to evaluate the indication for reoperation. PATIENTS: Recurrence of rupture was analysed in 25 out of a series of 109 patients who underwent surgical repair for postinfarction ventricular septal rupture between 1980 and 1992 in our institution. RESULTS: The mean interval between initial operation and recurrence was 3.6 days with a median of 2 days. Multivariate logistic regression analysis identified early thrombolysis after infarction (P = 0.0085) as a risk factor for recurrence of the rupture. Rupture recurrence occurred more in the anterior then in the posterior infarction site, although non-significant. Reoperation was indicated in 15 patients, in 13 for postrecurrent cardiac failure. The main determinant of cardiac failure was a large postrecurrent shunt (P = 0.05). The mean interval between initial operation and reoperation was 136 days with a median of 101 days. In 6 patients a combined apical ventricular septal rupture recurrence and anterior ventricular aneurysm was found, in 9 patients the recurrent rupture was proximally located, without concomitant aneurysm formation. Of 15 patients who were reoperated, one died in hospital and three after the in-hospital period. Of 10 patients treated conservatively, one died in hospital and two after the in-hospital period. One residual ventricular septal rupture closed spontaneously. CONCLUSIONS: Rupture recurrence is mainly determined by early thrombolysis. Postrecurrent cardiac failure, as the main indication for reoperation, is dependent on postrecurrent shunt size. 相似文献
88.
JH Patton TC Fabian MA Croce G Minard FE Pritchard KA Kudsk 《Canadian Metallurgical Quarterly》1996,41(2):231-6; discussion 236-7
The efficacy of prophylactic vena caval filters (VCF) in reducing morbidity and mortality from pulmonary embolism (PE) in high-risk trauma patients has been shown, but minimal follow-up data is currently available. VCFs were prophylactically placed in 110 patients between August 1991 and June 1995. There was an early VCF complication rate of 7%. Twenty-two patients died; the remaining 88 patients formed the basis for the follow-up study. Forty-five patients were located and interviewed by phone, and 30 of these patients (34%) returned for evaluation. The mean follow-up time was 18 months (range, 4-42 months). There was no incidence of caval thrombosis on follow-up. Eleven patients had physical findings, and duplex evidence consistent with postphlebitic syndrome. An additional three patients had evidence of old deep venous thrombosis (DVT) by duplex, but no significant symptomatology. VCF are effective in preventing PE related deaths and have few major complications. The long-term morbidity associated with posttraumatic venous thrombosis is significant. This morbidity is related not to PE or VCF, but to the underlying DVT. Improved strategies against DVT are necessary. 相似文献
89.
FE Visser M Kuilman J Oosting J Overweg J van Wijk AC van Huffelen 《Canadian Metallurgical Quarterly》1996,94(2):97-103
Asthma is one of the most common chronic illnesses in childhood. Increases in hospitalization rates have occurred in several countries. The cumulative risk of asthma requiring medical attention was 11.7% for males and 7.0% for females aged 0-4 in Manitoba, Canada, for the cohort of children born in 1984/1985. The cumulative risk of hospitalization for males was nearly twice that of females (2.1% vs. 1.1%). Disease onset was most likely at age 1 year. The risk of rehospitalization or return physician visit for asthma increased significantly with the number of prior hospitalizations and physician visits, respectively, which may reflect both the persistence of asthma and the difficulty of developing an effective disease management strategy. 相似文献
90.