全文获取类型
收费全文 | 2006篇 |
免费 | 0篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 10篇 |
轻工业 | 4篇 |
冶金工业 | 1977篇 |
自动化技术 | 14篇 |
出版年
2022年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2017年 | 1篇 |
2011年 | 1篇 |
2009年 | 2篇 |
2008年 | 2篇 |
2006年 | 2篇 |
2003年 | 6篇 |
1999年 | 65篇 |
1998年 | 664篇 |
1997年 | 373篇 |
1996年 | 243篇 |
1995年 | 130篇 |
1994年 | 90篇 |
1993年 | 111篇 |
1992年 | 9篇 |
1991年 | 13篇 |
1990年 | 29篇 |
1989年 | 29篇 |
1988年 | 16篇 |
1987年 | 11篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 11篇 |
1981年 | 18篇 |
1980年 | 12篇 |
1979年 | 3篇 |
1978年 | 7篇 |
1977年 | 37篇 |
1976年 | 78篇 |
1975年 | 7篇 |
1973年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有2006条查询结果,搜索用时 15 毫秒
61.
YY Kong KD Fischer MF Bachmann S Mariathasan I Kozieradzki MP Nghiem D Bouchard A Bernstein PS Ohashi JM Penninger 《Canadian Metallurgical Quarterly》1998,188(11):2099-2111
Homologies between vertebrate forebrain subdivisions are still uncertain. In particular the identification of homologs of the mammalian neocortex or the dorsal ventricular ridge (DVR) of birds and reptiles is still a matter of dispute. To get insight about the organization of the primordia of the main telencephalic subdivisions along the anteroposterior axis of the neural tube, a fate map of the dorsal prosencephalon was obtained in avian chimeras at the 8- to 9-somite stage. At this stage, the primordia of the pallium, DVR and striatum were located on the dorsal aspect of the prosencephalon and ordered caudorostrally along the longitudinal axis of the brain. Expression of homeobox-containing genes of the Emx, Dlx and Pax families were used as markers of anteroposterior developmental subdivisions of the forebrain in mouse, chick, turtle and frog. Their expression domains delineated three main telencephalic subdivisions in all species at the onset of neurogenesis: the pallial, intermediate and striatal neuroepithelial domains. The fate of the intermediate subdivisions diverged, however, between species at later stages of development. Homologies between forebrain subdivisions are proposed based on the conservation and divergence of these gene expression patterns. 相似文献
62.
DD De La Tour D Raccah MF Jannot T Coste C Rougerie P Vague 《Canadian Metallurgical Quarterly》1998,41(9):1080-1084
The purpose of this study is to clarify the volume effect of epidural saline injection 20 min after spinal anesthesia. Thirty patients undergoing combined spinal and epidural anesthesia for orthopedic surgery were randomly divided into two groups: a control group (n = 15) and a saline group (n = 15). In the control group, 2% lidocaine 3 ml with 0.4% tetracaine was injected into the subarachnoid space from L 4-5 interspace using Durasafe (Becton Dickinson, USA) and saline was not injected into the epidural space. In the saline group, saline 10 ml was injected through an epidural catheter 20 min after spinal anesthesia. The levels of analgesia 20 min after spinal anesthesia were not significantly different between the groups. However, the levels of analgesia 3, 5, 10, 40 and 100 min after epidural saline injection in the saline group were significantly higher than those in the control group (P < 0.05). The highest analgesic level was obtained 10 min after epidural saline injection and reached to T 4.3 +/- 1.1. In conclusion, epidural saline injection increases the analgesic level 20 min after spinal anesthesia because of the volume effect. 相似文献
63.
64.
RS Moorthy AT Lyon MF Rabb RF Spaide LA Yannuzzi LM Jampol 《Canadian Metallurgical Quarterly》1998,105(8):1380-1385
OBJECTIVE: The authors evaluated the clinical, fluorescein, and indocyanine green (ICG) angiographic characteristics of the macular variant of idiopathic polypoidal choroidal vasculopathy (IPCV). DESIGN: Observational case series. PARTICIPANTS: The records, photographs, and fluorescein and ICG angiograms of eight eyes of seven patients with IPCV lesions confined to the macula were reviewed. MAIN OUTCOME MEASURES: The visual acuity, fundus examination, fluorescein and ICG angiographic characteristics, and clinical course were compared. RESULTS: All patients demonstrated polypoidal lesions arising from macular choroidal vessels on ICG angiography. One patient had bilateral lesions. These lesions appeared hyperfluorescent in the early phases of both fluorescein and ICG angiography. Late-phase leakage was seen in cases associated with subretinal fluid or exudate. None of these patients demonstrated polypoidal lesions arising from the peripapillary choroidal circulation or peripapillary choroidal neovascularization. Three eyes with polypoidal lesions that were associated with subretinal fluid and exudates were treated with photocoagulation. Five eyes were not treated. Final visual acuity ranged from 20/20 to hand motions. Severe visual loss was associated with vitreous and subretinal hemorrhage, but this resolved without permanent severe visual loss in several cases. CONCLUSIONS: In the macular variant of IPCV, ICG and fluorescein angiography demonstrate characteristic macular polypoidal lesions without evidence of peripapillary lesions. The vascular origin of these polypoidal lesions appears to be the macular choroidal circulation. This is distinguished from classic IPCV, in which lesions appear to arise from the peripapillary choroidal circulation. Visual prognosis appears to be good, with most patients retaining visual acuity of 20/80 or better. If subretinal fluid or exudates reduce visual acuity, photocoagulation should be considered. 相似文献
65.
RM Enrici AP Anselmo V Iacari MF Osti M Santoro V Tombolini F Mandelli C Biagini 《Canadian Metallurgical Quarterly》1998,83(7):636-644
BACKGROUND AND OBJECTIVE: One of the consequences of the enormous improvement in survival rates of patients treated for Hodgkin's disease (HD) is the emergence in the long term of treatment-related complications, particularly secondary cancers. This study was undertaken to observe the occurrence of non-Hodgkin's lymphoma (NHL) in patients treated for HD and to identify the etiological role of various risk factors, especially spleen irradiation, in the pathogenesis of this illness. DESIGN AND METHODS: From 1972 to 1996, the Department of Radiation Oncology and the Hematology Section of "La Sapienza" University of Rome observed and analyzed the occurrence of NHL in 1,391 patients treated for HD. The average follow-up period was 84 months. For a more accurate calculation of the risk of the occurrence of NHL, the patients were first divided into 3 groups according to their initial treatment and also according to the total treatment they had received. Then, in order to establish the possible connection between NHL and splenic treatment the patients were also divided into 3 subgroups according to whether they had undergone splenectomy, splenic irradiation or neither of these. Two different methods of statistical analysis were used: (a) the cumulative risk (confidence interval) was evaluated in relation to treatment (initial and at the time of salvage) and (b) the Cox model was applied to identify the variables which play a role in the appearance of NHL. The cumulative risk of developing NHL was assessed using the Kaplan and Meier method. A multivariate analysis was performed using the Cox Proportional Hazard Model. RESULTS: A total of 20 cases of NHL were observed, appearing between 17 and 206 months after initial treatment. The cumulative risk was 0.8%, 1.8%, 2.6% and 3.5% at 5, 10, 15 and 20 years respectively. According to the multivariate analysis, significant risk factors were splenic irradiation and age (> 40 years). Splenic irradiation (vs no splenectomy/no splenic irradiation) showed a relative risk of 5.69, p = 0.0280, while age over 40 showed a relative risk of 3.05, p = 0.0152. INTERPRETATION AND CONCLUSIONS: From the results of this study, if appears that there is a possibility that splenic irradiation and age over 40 increase the risk of NHL in HD patients. Further studies are needed to investigate in greater depth the role of spleen irradiation in the occurrence of this illness. 相似文献
66.
MF Nielsen R Basu S Wise A Caumo C Cobelli RA Rizza 《Canadian Metallurgical Quarterly》1998,47(11):1735-1747
The present studies were undertaken to determine whether people with type 2 diabetes are resistant to the effects of glucose as well as insulin. Diabetic and nondiabetic subjects were studied on three occasions. Hormone secretion was inhibited with somatostatin. Insulin concentrations were kept at "basal" levels (referred to as low insulin infusion) from 0 to 180 min then increased to approximately 200 pmol/l from 181 to 360 min (referred to as high insulin infusion). Glucose concentrations were clamped at either approximately 95, approximately 130, or approximately 165 mg/dl on each occasion. In the presence of basal insulin concentrations, a progressive increase in glucose from 95 to 130 to 165 mg/dl was accompanied by a comparable and progressive decrease (P = 0.001 to 0.003 by analysis of variance [ANOVA]) in endogenous glucose production (measured with [6-(3)H]glucose) and total glucose output (measured with [2-(3)H]glucose) and incorporation of 14CO2 into glucose (an index of gluconeogenesis) in both diabetic and nondiabetic subjects, indicating normal hepatic (and perhaps renal) response to glucose. In the nondiabetic subjects, an increase in glucose concentration from 95 to 130 to 165 mg/dl resulted in a progressive increase in glucose disappearance during both the low (19.9 +/- 1.8 to 23.6 +/- 1.8 to 25.4 +/- 1.6 micromol x kg(-1) x min(-1); P = 0.003 by ANOVA) and high (36.4 +/- 3.1 to 47.6 +/- 4.5 to 61.1 +/- 7.0 micromol x kg(-1) x min(-1); P = 0.001 by ANOVA) insulin infusions. In contrast, in the diabetic subjects, whereas an increase in glucose from 95 to 130 mg/dl resulted in an increase in glucose disappearance during both the low (P = 0.001) and high (P = 0.01) dose insulin infusions, a further increase in glucose concentration to 165 mg/dl had no further effect (P = 0.41 and 0.38) on disappearance at either insulin dose (low: 14.2 +/- 0.8 to 18.2 +/- 1.1 to 18.7 +/- 2.4 micromol x kg(-1) x min(-1); high: 21.0 +/- 3.2 to 33.9 +/- 6.4 to 32.5 +/- 8.0 micromol x kg(-1) x min(-1) for 95, 130, and 165 mg/dl, respectively). We conclude that whereas glucose-induced stimulation of its own uptake is abnormal in type 2 diabetes, glucose-induced suppression of endogenous glucose production and output is not. The abnormality in uptake occurs in the presence of both basal and high insulin concentrations and is evident at glucose concentrations above but not below 130 mg/dl, implying a defect in a glucose-responsive step. 相似文献
67.
HP Grocott ND Croughwell DW Amory WD White JL Kirchner MF Newman 《Canadian Metallurgical Quarterly》1998,65(6):1645-9; discussion 1649-50
BACKGROUND: The glial protein S100beta has been used to estimate cerebral damage in a number of clinical settings. The purpose of this investigation was to determine the correlation between cerebral microemboli and S100beta levels during cardiac operations. METHODS: Transcranial Doppler ultrasonography was used to measure emboli in the right middle cerebral artery. Emboli counts (n = 111) were divided into five time periods: (1) incision to aortic cannulation; (2) aortic cannulation to cross-clamp onset; (3) cross-clamp onset to cross-clamp release; (4) cross-clamp release to decannulation; and (5) decannulation to chest closure. The level of S100beta (n = 156) was measured at baseline, at the end of cardiopulmonary bypass, then 150 and 270 minutes after cross-clamp release. RESULTS: The level of S100beta correlated with age, cardiopulmonary bypass time, cross-clamp time, and number of emboli at time period 2. Although cardiopulmonary bypass time was univariately associated with S100beta level, it became nonsignificant in a multivariable model that included age and cross-clamp time. CONCLUSIONS: The correlation of S100beta level with emboli measured during cannulation (time period 2) supports the hypothesis that cannulation is a high-risk time period for cerebral injury. 相似文献
68.
VI Novoselov IV Peshenko VA Evdokimov SS Kamzalov SV Novoselov IuV Nikolaev MF Bystrova EE Fesenko 《Canadian Metallurgical Quarterly》1998,43(4):610-616
BACKGROUND: Percutaneous mitral valvuloplasty with the Inoue balloon is conventionally performed with double vascular access: arterial and venous. However, in patients with a good echogenic window it may be performed with venous access only and the procedure monitored by 2D-echocardiography and colour flow mapping. This should result in early ambulation and hospital discharge with reduced arterial complications. AIMS: To compare retrospectively the immediate results of percutaneous mitral valvuloplasty with the Inoue balloon in two groups of patients: Group I: venous access only (no arterial access, n = 102) and Group II: conventional double vascular access (arterial and venous access, n = 275). METHODS AND RESULTS: The baseline characteristics of the two groups were comparable for age, sex, clinical, echocardiographic, radiological and haemodynamic variables. The mitral valve area (Group I: 1.1 +/- 0.3 to 1.85 +/- 0.5 cm2 vs Group II: 1.05 +/- 0.2 to 1.85 +/- 0.5 cm2, P = ns) and transmitral gradient (Group I: 11 +/- 4 to 4.7 +/- 2 mmHg vs Group II: 12 +/- 4 to 4.8 +/- 2 mmHg, P = ns) before and after mitral valvuloplasty were not statistically different. A good immediate result, defined as mitral valve area > 1.5 cm2 and mean mitral gradient < 5 mmHg with mitral regurgitation < or = 2+ at the end of the procedure, was observed in 77% of the cases in the venous-only group and 79% in the double access group (P = ns). The incidence of severe mitral regurgitation (Grade III or IV) was not statistically significant. Procedural duration (71 +/- 24 min vs 109 +/- 26 min, P < 0.01), fluoroscopic time (12.5 +/- 5.5 min vs 18.5 +/- 6 min, P < 0.01) and hospital stay (2.8 +/- 1.5 days vs 4.8 +/- 2.6 days, P < 0.001) were significantly shorter in the venous-only group than in the conventional Inoue series. CONCLUSION: Single venous access balloon mitral valvuloplasty is as equally safe and effective as double vascular access. The additional advantages of single venous access are shorter procedural duration, fluoroscopic time and hospital stay. We recommend that it be performed by an experienced operator (minimum of 100 trans-septal punctures) in patients without major thoracic deformity and a good echogenic window. 相似文献
69.
MF Nitschke UH Melchert C Hahn V Otto H Arnold HD Herrmann G Nowak M Westphal K Wessel 《Canadian Metallurgical Quarterly》1998,140(12):1223-1229
Intracranial lesions may compromise structures critical for motor performance, and mapping of the cortex, especially of the motor hand area, is important to reduce postoperative morbidity. We investigated nine patients with parietal lobe tumours and used functional MRI sensitized to changes in blood oxygenation to define the different motor areas, especially the primary sensorimotor cortex, in relation to the localization of the tumour. Activation was determined by pixel-by-pixel correlation of the signal intensity time course with a reference waveform equivalent to the stimulus protocol. All subjects showed significant activation of the primary sensorimotor cortex while performing a finger opposition task with the affected and unaffected side. In five patients the finger opposition task additionally activated the ipsilateral sensorimotor cortex and the supplementary motor area (SMA). Extension and flexion of the foot, additionally performed in two patients, also activated the sensorimotor cortex, in one case within the perifocal oedema of the tumour. Tumour localization near the central sulcus induced displacement of the sensorimotor cortex as compared to the unaffected side in all patients with a relevant mass effect. The results of our study demonstrate that functional MRI at 1.5 T with a clinically used tomograph can reproducibly localize critical brain regions in patients with intracranial lesions. 相似文献
70.
TC Chao LB Jeng YY Jan TL Hwang CS Wang MF Chen 《Canadian Metallurgical Quarterly》1998,45(22):921-926
BACKGROUND/AIMS: Primary carcinoma of the gallbladder is rare and associated with a late diagnosis and poor prognosis. Concurrent acute cholecystitis frequently obscures the presence of carcinoma. The information regarding gallbladder carcinoma with acute cholecystitis is limited. In order to better understand the presentation of gallbladder carcinoma with acute cholecystitis, we retrospectively reviewed the data of patients with primary carcinoma of the gallbladder. METHODOLOGY: The data of 86 patients with primary carcinoma of the gallbladder treated between 1979 and 1994 were compiled and reviewed. The patients were divided into 2 groups: Group 1 (with acute cholecystitis, 21 patients) and Group 2 (without cholecystitis, 65 patients). Clinicopathological comparisons were made and evaluated between these two groups RESULTS: The average age of Group 1 patients was older than that of Group 2 patients (75+/-2 years vs. 63+/-2 years; p<0.05). Three Group 1 patients presented with sepsis. The interval between the onset of symptoms and hospital admission in Group 2 patients was significantly (p<0.05) longer than that in Group 1 patients (243+/-95 days vs. 20+/-11 days). Leukocytosis (>11,000/mm3) was more common in Group 1 patients than in Group 2 patients (47.6% vs. 15.4%). Jaundice was more common in Group 2, and fever was common in Group 1. The majority of Group 2 gallbladder cancers were stage V (75.4%). In contrast, 52.4% of Group 1 gallbladder cancers were stage III and 38.1% were stage V. The 30-day postoperative mortality rate in Group 1 and Group 2 patients was 9.5% and 7.7%, respectively. The cumulative survival of Group 1 patients was not different from that of Group 2 patients (log-rank test, p>0.05). CONCLUSIONS: Age, the interval of symptoms prior to admission, the location of abdominal pain, fever, leukocytosis, and the absence of jaundice suggested the presence of acute cholecystitis in gallbladder carcinoma. A high index of suspicion of the disease, intraoperative examination of gallbladder specimens, and more aggressive surgical treatment may improve patient survival. 相似文献