全文获取类型
收费全文 | 1267篇 |
免费 | 18篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 18篇 |
金属工艺 | 8篇 |
能源动力 | 2篇 |
轻工业 | 4篇 |
无线电 | 11篇 |
一般工业技术 | 45篇 |
冶金工业 | 1170篇 |
原子能技术 | 2篇 |
自动化技术 | 23篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 5篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 6篇 |
2013年 | 10篇 |
2012年 | 14篇 |
2011年 | 3篇 |
2010年 | 1篇 |
2009年 | 2篇 |
2008年 | 8篇 |
2007年 | 6篇 |
2006年 | 6篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 39篇 |
1998年 | 355篇 |
1997年 | 200篇 |
1996年 | 142篇 |
1995年 | 85篇 |
1994年 | 50篇 |
1993年 | 80篇 |
1992年 | 9篇 |
1991年 | 23篇 |
1990年 | 15篇 |
1989年 | 25篇 |
1988年 | 13篇 |
1987年 | 14篇 |
1986年 | 20篇 |
1985年 | 19篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 15篇 |
1978年 | 1篇 |
1977年 | 22篇 |
1976年 | 40篇 |
1975年 | 3篇 |
1955年 | 1篇 |
排序方式: 共有1285条查询结果,搜索用时 15 毫秒
981.
BV Eden RF Debo JM Larner MD Kelly PA Levine FM Stewart RW Cantrell WC Constable 《Canadian Metallurgical Quarterly》1994,73(10):2556-2562
BACKGROUND: Esthesioneuroblastoma is a rare tumor arising from olfactory epithelium. This retrospective review analyzed the patterns of failure and long term outcome of patients with esthesioneuroblastoma evaluated at a single institution. METHODS: Forty patients with esthesioneuroblastoma were evaluated at the University of Virginia, with a median follow-up of 130 months. In most cases, treatment consisted of combined-modality therapy, including radiotherapy and surgery for Stages A and B disease and the addition of chemotherapy for Stage C disease. Fifteen patients received chemotherapy that included cyclophosphamide plus vincristine. Thirty-eight patients received radiotherapy, with a median dose of 50 Gy. Initial surgery for 23 patients included craniofacial resection, whereas the remainder had less extensive surgery (3 had no initial surgery). Five patients were salvaged with high dose chemotherapy and autologous bone marrow transplantation (CTX/BMT). RESULTS: Actuarial survivals at 5, 10, and 15 years are 78%, 71%, and 65% respectively. Fifty-five percent of patients failed therapy, and 68% of the failures were locoregional. Thirty-nine percent of recurrences occurred later than 5 years from diagnosis. Three of the five patients were successfully salvaged with CTX/BMT compared with four of seventeen patients who underwent conventional salvage therapy. CONCLUSIONS: Esthesioneuroblastoma is associated with long term survival and late recurrences. Multimodality therapy should be used initially. Durable remissions of failures can be achieved with CTX/BMT: 相似文献
982.
983.
MJ Perry FY Mortuza FM Ponsford CJ Elson RM Atkins 《Canadian Metallurgical Quarterly》1995,34(12):1127-1134
Quantitative immunophenotypic analysis of cell types present in peri-prosthetic tissue [pseudosynovial membrane (PSM)] from aseptically loose joint implants revealed considerable heterogeneity between tissues from different individuals. The monocyte/macrophage was the commonest leucocyte type; however, its proportion varied widely. T cells normally accounted for approximately 5% of cells, but in a few cases formed > 20% of cells. In all cases, there was a high ratio of CD4 to CD8 cells. PSM leucocytes were activated in most PSMs as judged by surface expression of CD23, CD25 and CD71. Analysis of the proportions of cell types in PSM, OA synovium and RA synovium revealed similarities between the different tissue types. The levels of IL-1, IL-6 and prostaglandin E produced by the PSM were correlated, but only IL-1 and IL-6 levels correlated with markers of the monocyte/macrophage lineage. This result suggests that prostaglandin E is produced in vivo by many PSM cell types. 相似文献
984.
FM Gibson J Scopes S Daly S Ball EC Gordon-Smith 《Canadian Metallurgical Quarterly》1995,91(3):551-561
Defective marrow stroma, or microenvironment, have been proposed as one of several mechanisms to account for bone marrow failure in aplastic anaemia (AA). This could involve defects in positive- or negative-acting haemopoietic regulator expression by AA stroma, or alteration of normal stroma-stem cell interactions. We have used a sensitive bioassay to investigate production of granulocyte-colony stimulating factor (G-CSF), granulocyte-macrophage-colony stimulating factor (GM-CSF), interleukin (IL)-3, IL-6 and stem cell growth factor (SCF), by normal and AA stroma in long-term bone marrow culture (LTBMC). LTBMC were grown to confluence, irradiated and harvested to yield a single cell suspension. These cells were cocultured with normal target bone marrow mononuclear cells (BMMC), or CD34+ cells, in clonogenic assays, in the absence of exogenous cytokines. Cytokines responsible for the colony-stimulating activity (CSA) and burst-promoting activity (BPA) produced by stromal cells were identified by neutralizing antibodies to specific cytokines. All normal stroma populations produced G-CSF and GM-CSF, 93% produced IL-3, 80% produced IL-6, and 70% produced SCF. Similarly, all AA stroma produced G-CSF and GM-CSF, and 71% produced SCF. In contrast, only 71% of AA stroma produced IL-3 and 36% produced IL-6. Target cell stimulation was not dependent on direct stroma-target cell contact, suggesting production of soluble cytokines. However, although both IL-6 and G-CSF were detected in LTBMC supernatants by enzyme-linked immunoassay (ELISA), IL-3 and GM-CSF were undetectable, perhaps indicating low-level local production of these factors. 相似文献
985.
In the gerbil (Meriones unguiculatus) hippocampal formation, the calcium-binding protein parvalbumin (PV) shows a unique species-specific distribution: it is present in the perforant path from the entorhinal cortex to the stratum molecular of the dentate are and cornu ammonis. A possible relation of this to the seizure-sensitivity of gerbils has been suggested. In addition, as in other species, PV is contained in a subpopulation of GABAergic nerve cells of the gerbil hippocampus. The characteristics of these PV-containing neurons are here described. Distribution and shape of the PV-positive neurons in general agreed with the features described for rat hippocampus with two notable exceptions: in CA2 PV-containing perikarya were densely crowded and gave rise to an intense immunoreactive plexus around the pyramidal cells and, in CA1, the number of stained neurons was variable, often much lower than in rats and occasionally not a single PV-positive neuron was present. In parasagittal brain sections of the lateralities 1.0, 1.6 and 2.2 mm from the midline, obtained from 27 male gerbils, the number of PV-containing neurons was determined. The data set obtained in CA3 and dentate area resembled unimodal distributions, while in CA1 a bimodal frequency distribution was present. Since parametric and non-parametric correlation tests rely on a unimodal distribution of the data set, they gave falsely significant values in CA1. The bimodal distribution suggests that, with respect to the PV-containing interneurons in CA1, two different populations of gerbils were included in our sample, those with many positive neurons and those with only a few. Since the nerve terminal staining is preserved also in those gerbils with only a few positive perikarya in CA1, it seems possible that an unknown factor influenced PV expression and storage in the soma. Sex, age, seasonal or circadian rhythm or quality of immunocytochemical staining did not influence the outcome of the quantitative analysis. However, a relation of the expression of the high affinity calcium buffering PV in interneurons and the individual seizure sensitivity of the gerbil is considered. 相似文献
986.
987.
988.
989.
990.