全文获取类型
收费全文 | 678篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 38篇 |
金属工艺 | 2篇 |
机械仪表 | 1篇 |
矿业工程 | 5篇 |
轻工业 | 21篇 |
石油天然气 | 5篇 |
无线电 | 4篇 |
一般工业技术 | 18篇 |
冶金工业 | 580篇 |
原子能技术 | 1篇 |
自动化技术 | 3篇 |
出版年
2022年 | 4篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 6篇 |
2012年 | 6篇 |
2011年 | 6篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 4篇 |
2007年 | 4篇 |
2006年 | 5篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 3篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 8篇 |
1998年 | 160篇 |
1997年 | 95篇 |
1996年 | 64篇 |
1995年 | 38篇 |
1994年 | 21篇 |
1993年 | 25篇 |
1992年 | 13篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 9篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 13篇 |
1978年 | 3篇 |
1977年 | 27篇 |
1976年 | 74篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1966年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有679条查询结果,搜索用时 31 毫秒
91.
92.
CE Cox S Pendas NN Ku DS Reintgen HS Greenberg SV Nicosia 《Canadian Metallurgical Quarterly》1998,64(6):533-7; discussion 537-8
Successful breast conservation therapy with optimal cosmesis requires adequate tumor excision and negative tumor margins. Therefore, more sensitive techniques are being developed to identify lumpectomy margins intraoperatively with greater accuracy. Unidentified microscopic disease is seemingly responsible for a local recurrence rate of up to 25 per cent 3 to 5 years after lumpectomy and radiotherapy for breast cancer patients. As a result, Moffitt Cancer Center has routinely used an intraoperative touch preparation cytology (TPC) protocol to evaluate the entire resected surface of all lumpectomies. In addition, resection margins were also evaluated by gross examination and by standard histology. In rare instances frozen sections were used to evaluate tumor margins. In this study 701 consecutive lumpectomy specimens were evaluated by TPC during the period of 9 years with a mean follow-up of 3.5 years. Local cancer recurrence was 2.7 per cent (mean recurrence, 2.53 years), in women whose lumpectomy margins were evaluated by TPC. Of interest, a local recurrence rate of 14.6 per cent was observed in patients who had referral lumpectomies evaluated by conventional histopathology. This study suggests that accurate margin assessment with TPC plays an important role in the control of local recurrence after breast conservation therapy. Therefore, we conclude the routine use of intraoperative TPC provides rapid, reliable, topographically accurate identification of residual microscopic disease at lumpectomy margins. 相似文献
93.
R Nair G Ramakrishnan NN Nair TK Saikia PM Parikh SR Joshi CS Soman M Mukhadan KT Dinshaw SH Advani 《Canadian Metallurgical Quarterly》1998,82(11):2282-2288
BACKGROUND: Combination chemotherapy consisting of methotrexate, doxorubicin, cyclophosphamide, vincristine, prednisolone, and bleomycin (MACOP-B) has been frequently used for the treatment of non-Hodgkin's lymphoma. This randomized study was undertaken to assess the efficacy and toxicity of this regimen when either doxorubicin or epirubicin was used as the anthracycline drug. METHODS: Between April 1989 and December 1993, 211 previously untreated patients with intermediate grade and high grade non-Hodgkin's lymphoma were randomized to receive either doxorubicin (n=106) or epirubicin (n=105) with the MACOP-B regimen. These patients were followed through December 1996. Numerous clinical features predictive of response and survival were analyzed. Cardiac and noncardiac toxicity in the two treatment arms were compared. RESULTS: The median age of the patients was 48 years. Complete remission was experienced by 122 patients (58.3%); 62 patients (58.5%) achieved complete remission in the doxorubicin arm and 60 (58.1%) in the epirubicin arm. Response rates, time to treatment failure, relapse data, and overall survival were comparable between the two arms. Morbidity due to mucositis, vomiting, peripheral neuropathy, and cardiotoxicity were also comparable. The overall mortality was 10%. Mortality due to neutropenic sepsis was considerably higher among patients who received epirubicin (10 patients) than among those who received doxorubicin (5 patients). Cardiac evaluation revealed no difference in toxicity between the two arms. CONCLUSIONS: Epirubicin was as effective as doxorubicin in terms of patients' responses to therapy. There was no difference in cardiotoxicity between the two treatment arms. However, in this study, the mortality due to neutropenic sepsis was significantly higher among patients treated with epirubicin. 相似文献
94.
P Reiter R Cordellier JO Ouma CB Cropp HM Savage EJ Sanders AA Marfin PM Tukei NN Agata LG Gitau BA Rapuoda DJ Gubler 《Canadian Metallurgical Quarterly》1998,59(4):650-656
OBJECTIVES: The physiology of the female sexual response and its molecular mediators remain poorly understood. Nitric oxide (NO) is synthesized in neurons and is a potent relaxor of vascular and nonvascular smooth muscle. In this study, we hypothesize that vaginal atrophy and declining sexual function during menopause may be NO dependent. Using the rat as an experimental model, we examined the expression and topologic localization of vaginal NO synthase (NOS) and the concomitant induction of apoptosis under normal and estrogen-depleted conditions. METHODS: Thirty rats were categorized into six groups on the basis of phase of the estrous cycle or estrogen status after oophorectomy. The expression and cellular localization of NOS was examined in frozen sections using specific antibodies against neuronal (N-NOS) and endothelial NOS (E-NOS). Apoptotic cells were identified in situ using the terminal transferase technique (TUNEL). Trichome staining was performed in all specimens to determine smooth muscle/collagen ratios. RESULTS: N-NOS immunoreactivity was localized to nerve fibers supplying vaginal smooth muscle, perivascular nerve plexuses, and lamina propria. E-NOS was localized to vascular endothelium and perivascular smooth muscle fibers. Both E-NOS and N-NOS expression in intact cycling animals was highest during proestrous and lowest during metestrous. After oophorectomy, levels of both N-NOS and E-NOS declined substantially compared with those of intact animals, and there was a parallel induction of apoptosis. Estrogen withdrawal also resulted in increased vaginal atrophy, intramural collagen accumulation, and perivascular wall thickening, as identified by trichome staining. Estrogen replacement resulted in a significant increase in E-NOS and N-NOS expression, as well as diminished apoptosis and vaginal atrophy. CONCLUSIONS: This cellular distribution of NOS in the rat vagina suggests that NO may modulate both vaginal blood supply and vaginal smooth musculature. Estrogen appears to play a critical role in concomitantly regulating vaginal NOS expression and apoptosis in nerves, smooth muscle, vascular endothelium, and epithelium of the rat vagina. These findings may have significant clinical implications for the pathophysiology of postmenopausal female sexual dysfunction. 相似文献
95.
Prediction of major depression and dysthymia from CES-D scores among ethnic minority adolescents 总被引:5,自引:0,他引:5
CA Prescott JJ McArdle ES Hishinuma RC Johnson RH Miyamoto NN Andrade JL Edman GK Makini LB Nahulu NY Yuen BS Carlton 《Canadian Metallurgical Quarterly》1998,37(5):495-503
Two tumour cell clones, 6D1 and 4C2 cells, which are defective both in the major histocompatibility gene complex (MHC) class I expression and in the endogenous antigen presentation, are recovered with interferon (IFN)-gamma treatment. The present study describes the ultrastructure of these cells by using scanning and transmission electron microscopy in relation to the effect of IFN-gamma treatment. The general morphology of these cells was found to be similar to each other and comparable to that of a tumour cell clone, 4A1 cells, of the same origin, normal in MHC class I expression; they exhibited a fibroblast-like appearance and had many blebs on all the cell surfaces, with desmosome-like junctions between cells. On IFN-gamma treatment, surface fine blebs appeared less, and mitochondria became more densely stained. Expression of MHC class I molecules on the cell surface was much higher in the IFN-gamma treated 6D1 and 4C2 cells than in untreated cells, when estimated by immunoelectron microscopy. The addition of an epitope peptide to these cells did not enhance the class I expression, which differed from other antigen presentation-defective cells such as RMA-S cells, nor change the cell surface morphology. 相似文献
96.
97.
The contraction of native collagen lattices by resident mesenchymal cells mimics the organization of collagen during development and repair. Lattice contraction is cell density dependent, suggesting that cell-to-cell communications may contribute to the process. This possibility was investigated by comparing lattice contraction by four rat osteoblastic cell lines: ROS 17/2.8 cells (ROS); ROS transfected with an antisense cDNA sequence of the gap junctional protein connexin 43 (RCx16); ROS transfected with connexin 45 cDNA, a connexin not normally expressed in ROS cells (ROS/Cx45); and ROS transfected with cDNA encoding carboxy-terminal truncated Cx45 (ROS/Cx45tr). The cell coupling indices, which reflect gap junctional communication, were quantitated by the fluorescent dye scrape loading. ROS cells were well coupled (index 3.0), ROS/Cx45tr were better coupled (index 4.2), ROS/Cx45 were poorly coupled (index 1.7), and RCx16 showed no coupling (index 1.1). As determined by immunoblotting, the level of connexin 43 protein was increased in both ROS/Cx45tr and ROS/Cx45 cell lines compared with ROS cells, while the level in RCx16 cells was reduced. ROS populated collagen lattices (PCLs) contracted significantly more at day 5 (177 mm2 to 67 mm2) than ROS/Cx45tr (84 mm2), ROS/Cx45 (108 mm2), or RCx16 (114 mm2). Myosin ATPase activity, which is required for lattice contraction, was equivalent in all four cell lines, indicating that it was not responsible for inhibiting PCL contraction. ROS cells in collagen appeared elongated compared with the other cell lines which were more rounded. These experiments suggest gap junctional communication contributes to PCL contraction by resident osteoblasts. 相似文献
98.
NN Shu?kin 《Canadian Metallurgical Quarterly》1998,48(6):1129-1133
Changes in the structural proteins and hydration during aging is responsible for altered skin morphologic and mechanical properties manifested as wrinkling, sagging, loss of elasticity, or apparent dryness. To gain insight into the age-related alterations in protein conformation and water structure, we obtained Raman spectra from the sun-protected buttock skin representing chronologic aging and the sun-exposed forearm skin representing combined effects of photoaging and chronologic aging. Ten aged individuals (five men, five women; age range 74-87) and 10 control young individuals (five men, five women; age range 22-29) entered the study. In the photoaged forearm skin the positions of protein-specific amide I, amide III, and CH stretching bands were shifted, suggesting increased protein folding. In contrast, major changes were seen only in the amide I peak in chronologically aged skin. The intensity of the 3250 cm(-1) OH stretching band was increased in photoaged skin (but not in chronologically aged skin) indicating an increased water content. R(v) representation of the low-frequency region of Raman spectra was applied to determine water structure. In the young skin and chronologically aged skin water was mostly present in the bound form. In the photoaged skin, however, an increase in intensity at 180 cm(-1) was noted, which reflects an increase in the not-protein bound water (tetrahedron water clusters). In conclusion, it seems that proteins in the photoaged skin are more compact and interact with water to limited degree. Impairment in protein hydration may add to the understanding of ultrastructural, mechanical, and biochemical changes in structural proteins in the aged skin. 相似文献
99.
OBJECTIVE: To examine in women with systemic lupus erythematosus (SLE) who participated in a clinical trial the relationship between daily dose of dehydroepiandrosterone (DHEA), serum levels of DHEA and DHEA sulfate (DHEAS), clinical effectiveness, and side effects. METHODS: Twenty-three women with mild to moderate SLE were treated with DHEA for a 6 month period. The starting dose was 50 mg/day, and monthly stepwise increases were allowed. Subjects were assessed monthly by the Systemic Lupus Erythematosus Disease Activity Index, Systemic Lupus Activity Measure (SLAM), Health Assessment Questionnaire, and other outcomes. Serum testosterone, DHEA, and DHEAS levels were obtained and side effects noted monthly. RESULTS: Statistically significant improvements were found in all lupus outcomes over 6 months. Serum DHEA and DHEAS levels correlated with the dose of DHEA. Serum DHEA and DHEAS correlated negatively with SLAM score. A second order regression analysis of serum DHEAS level versus SLAM score suggested that the optimal serum level of DHEAS was 1000 microg/dl. The most common side effect was acne. CONCLUSION: The clinical response to DHEA was not clearly dose dependent. Serum levels of DHEA and DHEAS correlated only weakly with lupus outcomes, but suggested an optimum serum DHEAS of 1000 microg/dl. Monitoring these serum levels appears to have limited clinical utility. 相似文献
100.
AM Antonov KM Chernov NA Iaitski? NN Grinenko MV Grigor''eva 《Canadian Metallurgical Quarterly》1998,157(5):144-145
Breech presentation occurs in 3-5% of deliveries and can be managed by either a trial of vaginal breech delivery (TOVBD), external cephalic version (ECV) or Caesarean section. A postal questionnaire was completed by 82% of Scottish consultant obstetricians and revealed wide variations in practice. Eighteen percent never offered ECV. Among those who did consensus was lacking on some contraindications. One-quarter sometimes performed ECV before 37 weeks gestations despite the possibility of spontaneous version. Only 70% restricted ECV to one or more designated operators thereby maintaining levels of expertise. Variations were demonstrated in the use of tocolytics, and pre and post procedure investigations. Following failed ECV 28% considered a repeat attempt and 56% a TOVBD. TOVBD was not offered as first line management by one-fifth of respondents. Those who did varied in the pre-procedure investigations performed. Guidelines are required to ensure safe, consistent practice and avoid unnecessary Caesarean sections. 相似文献