全文获取类型
收费全文 | 2759篇 |
免费 | 22篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 132篇 |
金属工艺 | 11篇 |
机械仪表 | 8篇 |
建筑科学 | 30篇 |
能源动力 | 8篇 |
轻工业 | 76篇 |
水利工程 | 8篇 |
石油天然气 | 1篇 |
无线电 | 31篇 |
一般工业技术 | 107篇 |
冶金工业 | 2309篇 |
原子能技术 | 3篇 |
自动化技术 | 54篇 |
出版年
2022年 | 9篇 |
2021年 | 11篇 |
2020年 | 9篇 |
2019年 | 13篇 |
2018年 | 15篇 |
2017年 | 26篇 |
2016年 | 12篇 |
2015年 | 14篇 |
2014年 | 25篇 |
2013年 | 31篇 |
2012年 | 38篇 |
2011年 | 23篇 |
2010年 | 22篇 |
2009年 | 18篇 |
2008年 | 23篇 |
2007年 | 19篇 |
2006年 | 21篇 |
2005年 | 11篇 |
2004年 | 18篇 |
2003年 | 14篇 |
2002年 | 14篇 |
2001年 | 16篇 |
2000年 | 7篇 |
1999年 | 86篇 |
1998年 | 735篇 |
1997年 | 449篇 |
1996年 | 263篇 |
1995年 | 138篇 |
1994年 | 103篇 |
1993年 | 138篇 |
1992年 | 22篇 |
1991年 | 25篇 |
1990年 | 18篇 |
1989年 | 28篇 |
1988年 | 37篇 |
1987年 | 22篇 |
1986年 | 16篇 |
1985年 | 15篇 |
1983年 | 4篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 17篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 62篇 |
1976年 | 150篇 |
1975年 | 5篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1955年 | 3篇 |
排序方式: 共有2783条查询结果,搜索用时 15 毫秒
71.
72.
Cystosarcoma phyllodes of the prostate is a rare, relatively benign sarcoma of the prostate. We describe the magnetic resonance imaging findings in an unusual case of cystosarcoma phyllodes which resulted in extensive local recurrence and sarcomatous degeneration. Although uncommon, radiologists should be aware of the existence of cystosarcoma phyllodes of the prostate. 相似文献
73.
74.
Cabrera Sara M.; Chavez Candice M.; Corley Sean R.; Kitto Michael R.; Butt Allen E. 《Canadian Metallurgical Quarterly》2006,120(2):298
The authors tested the hypothesis that the cholinergic nucleus basalis magnocellularis (NBM) is involved in solving problems requiring cognitive flexibility. Rats with 192 IgG-saporin lesions of the NBM were assessed for perseveration (i.e., cognitive inflexibility) in the serial reversal of an operant discrimination and during subsequent extinction testing. It was hypothesized that the NBM lesion and control groups would not differ in the acquisition of the initial, simple discrimination, because this task does not demand cognitive flexibility. In contrast, it was hypothesized that the NBM lesion group would show perseveration during serial reversal and extinction testing. Results generally supported these hypotheses, suggesting that the NBM plays an important role in mediating cognitive flexibility. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
75.
CK Goldman RL Kendall G Cabrera L Soroceanu Y Heike GY Gillespie GP Siegal X Mao AJ Bett WR Huckle KA Thomas DT Curiel 《Canadian Metallurgical Quarterly》1998,95(15):8795-8800
Vascular endothelial growth factor (VEGF) is a potent and selective vascular endothelial cell mitogen and angiogenic factor. VEGF expression is elevated in a wide variety of solid tumors and is thought to support their growth by enhancing tumor neovascularization. To block VEGF-dependent angiogenesis, tumor cells were transfected with cDNA encoding the native soluble FLT-1 (sFLT-1) truncated VEGF receptor which can function both by sequestering VEGF and, in a dominant negative fashion, by forming inactive heterodimers with membrane-spanning VEGF receptors. Transient transfection of HT-1080 human fibrosarcoma cells with a gene encoding sFLT-1 significantly inhibited their implantation and growth in the lungs of nude mice following i.v. injection and their growth as nodules from cells injected s.c. High sFLT-1 expressing stably transfected HT-1080 clones grew even slower as s.c. tumors. Finally, survival was significantly prolonged in mice injected intracranially with human glioblastoma cells stably transfected with the sflt-1 gene. The ability of sFLT-1 protein to inhibit tumor growth is presumably attributable to its paracrine inhibition of tumor angiogenesis in vivo, since it did not affect tumor cell mitogenesis in vitro. These results not only support VEGF receptors as antiangiogenic targets but also demonstrate that sflt-1 gene therapy might be a feasible approach for inhibiting tumor angiogenesis and growth. 相似文献
76.
EM Verdegaal ST Zegveld H Beekhuizen W Bakker R van Furth 《Canadian Metallurgical Quarterly》1998,22(2):215-227
Four mouse vomeronasal receptors (mV1Rs) have been isolated by similarity to rat vomeronasal receptor (V1R) motifs. The four mV1Rs identified in this study are members of two distinct subfamilies. Specific in situ hybridization probes (ISH) derived from the 3' non-coding regions of the mV1R genes, were used to detect expression of a single receptor and probes from the homologous coding regions were used to detect expression of subfamily members. The ISH results showed that the mV1Rs expressing neurons were scattered in the middle/upper layer of the vomeronasal organ (VNO) sensory epithelium in serial VNO sections but were excluded from the deeper layers of the VNO sensory epithelium and these neurons were found to co-express the mRNA for the G-protein Galphai2, and were distinct from the deeper layers of the VNO sensory epithelium where the mRNA for Galphao positive neurons was located. 相似文献
77.
BACKGROUND: Monocytic tissue factor (TF), initiating the extrinsic blood coagulation pathway, is often upregulated under septic or inflammatory conditions. The complex activating mechanism remains largely unclear and no effective strategy has been firmly established. In this study, we used a model monocytic cell line (human leukemic THP-1 promonocytes) to address (1) the nature of TF activation in response to bacterial endotoxin and (2) the application of anti-inflammatory cytokines in relieving monocytic hypercoagulation. RESULTS: TF in THP-1 cells was substantially activated by exposure to bacterial endotoxin (LPS; 5 micrograms/ml) for 6 h. Human recombinant IL-4 (500 ng/ml) and IL-10 (500 ng/ml) inhibited TF activation induced by LPS. To determine if these cytokines depressed LPS recognition resulting in such inhibition, we employed an anti-CD14 mAb (UCHM-1; Sigma Chemical) to address the role of CD14 in LPS transmembrane signaling. LPS-induced TF activation was depressed by 35% upon inclusion of the anti-CD14 mAb (1:10 dilution). This antibody alone mimicked TF activation which accounted for 35% of the LPS-induced TF activation, suggesting the activating role of CD14 ligation. In addition, the anti-CD14 mAb elicited the production of nitric oxide (NO) which was found to be independent of TF activation. NO production could serve as an independent index for monitoring LPS recognition. IL-4 depressed the anti-CD14 mAb-induced TF activation as well as NO elicitation, indicating the blockade of CD14 ligation. In contrast, IL-10 showed differential inhibitory activities. TF activation induced by either LPS or anti-CD14 mAb was inhibited by IL-10 which did not show any inhibition on NO elicitation under these conditions. In a separate approach, neither IL-4 nor IL-10 inhibited phorbol ester-induced NO elicitation. More direct evidence came from an epifluorescent demonstration showing that IL-4 blocked binding of FITC-conjugated LPS and anti-CD14 mAb to THP-1 cells. CONCLUSIONS: Taken together, the results suggest that LPS action in relation to TF activation consists of CD14-independent and -dependent signaling including CD14 ligation. We also showed that anti-inflammatory cytokines (IL-4 and -10) significantly depressed TF activation. IL-4 antagonized CD14-dependent LPS recognition leading to the depression in TF activation. 相似文献
78.
DE Jenkins RL Redman EM Lam C Liu I Lin AM Arvin 《Canadian Metallurgical Quarterly》1998,178(4):940-948
Varicella immunization provided the opportunity to examine the kinetics of interleukin (IL)-10, IL-12 and interferon (IFN)-gamma production elicited during primary in vivo sensitization with proteins of varicella-zoster virus (VZV), a common human herpesvirus. VZV-specific IFN-gamma release and T cell proliferation were elicited by immunization and persisted through 15 months of follow-up. The induction of VZV-specific T cells and IgG antibodies was accompanied by transient increases in IL-10 and IL-12 production. T cell proliferation to VZV was significantly lower in adults at 15 months than in vaccinated children or naturally immune subjects and correlated with lower IFN-gamma responses in individual vaccinees. After primary immunity was induced, continued IL-12 production was not necessary to maintain the predominant Th1-type response elicited by VZV. Cytokine profiles observed during primary in vivo sensitization to VZV suggest that parallel increases in IFN-gamma and IL-10 may be important in the induction of immunity to some viral pathogens. 相似文献
79.
80.