全文获取类型
收费全文 | 481篇 |
免费 | 2篇 |
国内免费 | 2篇 |
专业分类
化学工业 | 9篇 |
机械仪表 | 4篇 |
轻工业 | 4篇 |
无线电 | 1篇 |
一般工业技术 | 1篇 |
冶金工业 | 460篇 |
自动化技术 | 6篇 |
出版年
2020年 | 2篇 |
2019年 | 1篇 |
2015年 | 2篇 |
2011年 | 1篇 |
2010年 | 1篇 |
2008年 | 1篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2004年 | 1篇 |
2003年 | 3篇 |
1999年 | 13篇 |
1998年 | 157篇 |
1997年 | 89篇 |
1996年 | 57篇 |
1995年 | 20篇 |
1994年 | 19篇 |
1993年 | 24篇 |
1992年 | 3篇 |
1991年 | 9篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 8篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 1篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1977年 | 11篇 |
1976年 | 24篇 |
1955年 | 1篇 |
排序方式: 共有485条查询结果,搜索用时 15 毫秒
141.
表面微观形貌的显微干涉检测原理及干涉显微镜发展现状 总被引:2,自引:1,他引:1
追踪分析世界上表面微观形貌检测方面显微干涉检测原理的最新进展 ,比较干涉显微镜用于检测表面微观形貌时具有的形式、结构特点 ,分析选型研制干涉显微镜可能遇到的问题及应该研究的方面。 相似文献
142.
143.
P de Nully Brown PO Jensen M Diamant BT Mortensen D Hovgaard P Gimsing NI Nissen 《Canadian Metallurgical Quarterly》1998,22(11):983-989
The plasma cell labeling index (PCLI) in patients with multiple myeloma (MM) is relatively low and this has been associated with the low rate of remission following chemotherapy. Interleukin-6 (IL-6) has been demonstrated to be a major growth factor of myeloma cells. In order to increase the S-phase proportion of myeloma cells, which might increase the sensitivity to chemotherapy, we gave rhIL-6 followed by chemotherapy to 15 myeloma patients with refractory disease. A total of 25 treatment cycles were administered since ten patients had two cycles. The rhIL-6 dose was 2.5 (n = 3), 5.0 (n = 6) and 10.0 microg/kg (n = 6) by subcutaneous injection once daily for 5 days and chemotherapy was administered on the last day of rhIL-6 injection. The effect of rhIL-6 treatment on labeling index (LI) was heterogeneous, but no statistically significant change was noted for this particular group as a whole. In two patients an increase (mean 7.7%) in LI of mononuclear bone marrow cells during the rhIL-6 treatment was demonstrated and in one patient a decrease of 2.8% was seen. Assessment of PCLI demonstrated an increase of 2.9% in one out of six patients and a decrease of 1.9% in one out of six patients. None of the 15 patients achieved remission according to standard criteria. During the rhIL-6 treatment, 14 of the 15 patients developed mild constitutional adverse events (AE) well known in patients treated with IL-6, and none of the AE in the subsequent chemotherapy phase were related to IL-6. In conclusion, our study demonstrated that rhIL-6 can be administered safely to patients with refractory MM, but the cell cycle recruitment approach was not sufficiently effective to be of clinical value. 相似文献
144.
Technetium-94m (T1/2 = 53 min) allows the in vivo study of technetium radiopharmaceuticals with positron emission tomography (PET). PET provides a quantitative assay of radioactivity with excellent temporal and spatial resolution, revealing biodistributions that were previously available only through in vitro assay methods. Technetium-94m, produced by the proton irradiation of natural molybdenum on an 11 MeV cyclotron, was extracted with an electrochemical etching technique. Technetium-94m-pertechnetate was prepared to make the myocardial perfusion agent teboroxime in an identical manner as 99mTcO4-. The increased absorbed radiation dose requires a sevenfold reduction in administered activity compared to 99mTc-teboroxime. Eleven clinical PET studies were performed and visually compared to 13N-ammonia. The clearance half-time for 94mTc-teboroxime was approximately 8 min, with a peak myocardial extraction of approximately 3% of the injected dose into a 400-g heart. These results confirm the potential of 94mTc PET for quantitatively studying the pharmacokinetics of new, and old, technetium agents in man. 相似文献
145.
HM Lander DP Hajjar BL Hempstead UA Mirza BT Chait S Campbell LA Quilliam 《Canadian Metallurgical Quarterly》1997,272(7):4323-4326
We have identified the site of molecular interaction between nitric oxide (NO) and p21(ras) responsible for initiation of signal transduction. We found that p21(ras) was singly S-nitrosylated and localized this modification to a fragment of p21(ras) containing Cys118. A mutant form of p21(ras), in which Cys118 was changed to a serine residue and termed p21(ras)C118S, was not S-nitrosylated. NO-related species stimulated guanine nucleotide exchange on wild-type p21(ras), resulting in an active form, but not on p21(ras)C118S. Furthermore, in contrast to parental Jurkat T cells, NO-related species did not stimulate mitogen-activated protein kinase activity in cells transfected with p21(ras)C118S. These data indicate that Cys118 is a critical site of redox regulation of p21(ras), and S-nitrosylation of this residue triggers guanine nucleotide exchange and downstream signaling. 相似文献
146.
BT Veering PM Ter Riet AG Burm R Stienstra JW Van Kleef 《Canadian Metallurgical Quarterly》1996,77(3):343-346
In this randomized, observer-blind study, we have examined, in elderly patients, the effect of site of injection on analgesia levels after spinal injection of 0.5% hyperbaric bupivacaine solution. Thirty male patients, aged 68-87 yr, undergoing minor urological surgery during spinal anaesthesia received 3 ml of a 0.5% hyperbaric bupivacaine solution at either the L3-4 (n = 15) or L4-5 (n = 15) interspace. The solution was injected with the patient in the sitting position. The patient remained sitting for 2 min and was then placed in the supine horizontal position. Analgesia levels were assessed bilaterally using pin-prick. The highest analgesia levels did not differ between groups (medians were approximately T7). There were no significant differences in the time to maximum cephalad spread of analgesia, maximum degree of motor block or haemodynamic changes. We conclude that injection at the L4-5 interspace has no advantage compared with injection at the L3-4 interspace. 相似文献
147.
S Mui M Briggs H Chung RB Wallace T Gomez-Isla GW Rebeck BT Hyman 《Canadian Metallurgical Quarterly》1996,47(1):196-201
Apolipoprotein E allele 4 (apoE epsilon 4) is a major risk factor for late-onset AD. Inheritance of this allele is associated with an earlier age of onset of dementia in individuals with AD. It is unknown whether other polymorphisms in the apoE gene may influence the effect of apoE epsilon 4 on AD. We screened portions of the promoter enhancer element and of the apoE receptor binding domain for other polymorphisms that could affect risk of AD. In particular, a C/G polymorphism at position +113 of the apoE mRNA in the apoE intron 1 enhancer element (IE1) has been recently identified. We found no other polymorphisms. We studied the relationship of the two alleles of the IE1 polymorphism with AD and found an apparent association between IE1 G and AD (n = 94; p = 0.0515). However, the IE1 G allele is also closely associated with apoE epsilon 4 (p < 0.0001). When the presence of apoE epsilon 4 is covaried, the association between the IE1 G allele and AD is no longer statistically significant (odds ratio = 1.29, 95% confidence interval: 0.44, 3.78). In contrast, epsilon 4 is still highly associated with AD when IE1 G is controlled for (odds ratio = 5.91, 95% confidence interval: 3.29, 10.63). Furthermore, there is no significant association between the age of onset of dementia and the inheritance of the G allele. We believe that the apparent association between IE1 G and AD is a consequence of the association between the epsilon 4 and IE1 G alleles. 相似文献
148.
The effect of in vivo ethanol consumption on cyclic AMP and delta-opioid receptors in mouse striatum
J Shen KW Chan BT Chen J Philippe F Sehba A Duttaroy J Carroll BC Yoburn 《Canadian Metallurgical Quarterly》1997,770(1-2):65-71
The participation of tyrosine kinase in the regulation of the glucocorticoid receptor (GR) was studied in primary cultured rat hepatocytes using the tyrosine kinase inhibitor herbimycin A. Herbimycin A decreased the number of high-affinity binding sites of glucocorticoids in the cytosolic fraction and increased the equilibrium dissociation constant (Kd). Western blot analysis revealed that it also decreased the amount of GR protein. On the other hand, cycloheximide did not affect the GR protein level. Although herbimycin A slightly increased the amount of GR protein in the nuclear fraction, the increase was much lower than that of its decrease in the cytosolic fraction. Therefore, the decrease of GR protein in the cytosolic fraction was not caused by the inhibition of GR protein synthesis nor the translocation of GR from cytosol to nuclei. As herbimycin A also suppressed the dexamethasone (Dex)-dependent induction of tyrosine aminotransferase (TAT) activity, the decrease of GR protein was followed by the suppression of the GR-mediated biological response. These findings indicate that tyrosine kinase is necessary for the maintenance of the level of GR protein and its affinity of binding sites in the cytosolic fraction. Our results also suggested that the increase of GR protein stability is the most probable explanation for the maintenance of its level. 相似文献
149.
OBJECTIVES: To evaluate the safety and potential efficacy of antithrombin III (AT III) in reducing mortality in patients with severe sepsis. DESIGN: Prospective, randomized, placebo-controlled, double-blind, phase II, multicenter, multinational clinical trial. SETTING: Seven academic medical center intensive care units (ICU) in Belgium, Denmark, the Netherlands, Norway and Sweden. PATIENTS: 42 patients with severe sepsis who received standard supportive care and antimicrobial therapy, in addition to the administration of AT III or placebo. INTERVENTIONS: Patients received either an intravenous loading dose of 3000 IU AT III followed by a maintenance dose of 1500 IU every 12 h for 5 days or equivalent amounts of placebo. MEASUREMENTS AND RESULTS: All patients were evaluated for safety and for 30-day all-cause mortality. CONCLUSIONS: The administration of AT III was safe and well-tolerated. It was followed by a 39 % reduction in 30-day all-cause mortality (NS). The reduction in mortality was accompanied by a considerably shorter stay in the ICU. Patients treated with AT III exhibited a better performance in overall severity of illness and organ failure scores (Acute Physiology and Chronic Health Evaluation II, multiple organ failure, organ system failure), which was noticeable soon after initiation of treatment. Patients treated with AT III demonstrated a better resolution of pre-existing organ failures and a lower incidence of new organ failures during the observation period. A meta-analysis comprising this and two other double-blind, placebo-controlled trials with AT III with a total of 122 patients suffering from severe sepsis confirms the positive trend. The results of the meta-analysis demonstrate a 22.9 % reduction in 30-day all-cause mortality in patients treated with AT III. Although still too small to be confirmative, the meta-analysis clearly points to the fact that a sufficiently powered phase III trial is warranted to prove whether AT III has a beneficial role in the treatment of severe sepsis. 相似文献
150.
DA Lang G Neil-Dwyer BT Evans P Sarsfield E Nenji 《Canadian Metallurgical Quarterly》1996,12(4):218-221
A case of cranial fasciitis of childhood is described. This extensive cranio-orbital-facial lesion in a 3-month-old baby necessitated radical resection and immediate orbital and anterior cranial fossa reconstruction. The particular requirements of reconstruction in the infant are emphasised. 相似文献