全文获取类型
收费全文 | 2193篇 |
免费 | 5篇 |
专业分类
化学工业 | 15篇 |
金属工艺 | 2篇 |
建筑科学 | 1篇 |
能源动力 | 1篇 |
轻工业 | 3篇 |
石油天然气 | 1篇 |
无线电 | 14篇 |
一般工业技术 | 11篇 |
冶金工业 | 2137篇 |
自动化技术 | 13篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 5篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 2篇 |
2012年 | 1篇 |
2011年 | 1篇 |
2008年 | 1篇 |
2006年 | 2篇 |
2004年 | 3篇 |
2003年 | 2篇 |
1999年 | 70篇 |
1998年 | 624篇 |
1997年 | 359篇 |
1996年 | 265篇 |
1995年 | 155篇 |
1994年 | 117篇 |
1993年 | 126篇 |
1992年 | 21篇 |
1991年 | 34篇 |
1990年 | 26篇 |
1989年 | 39篇 |
1988年 | 43篇 |
1987年 | 38篇 |
1986年 | 25篇 |
1985年 | 35篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 10篇 |
1981年 | 15篇 |
1980年 | 14篇 |
1978年 | 3篇 |
1977年 | 40篇 |
1976年 | 88篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1966年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有2198条查询结果,搜索用时 0 毫秒
121.
GM Birch T Black SK Malcolm MT Lai RE Zimmerman SR Jaskunas 《Canadian Metallurgical Quarterly》1995,6(5):609-618
A physiologically relevant thrombopoietin (TPO) must be a humoral regulator with lineage specificity for megakaryocytes and their precursors. It should be capable of stimulating platelet production in normal animals, and elevated levels of TPO should be detectable in the plasma following acute, severe thrombocytopenia. Acute thrombocytopenia provides a model system that is likely to predict the effects of TPO, since many of the effects on megakaryocytes and platelets observed after induction of acute thrombocytopenia would be mediated by TPO. Important questions remain to be answered. Do the currently available data for the c-Mpl ligand explain previously published data that describe elevated levels of Meg-CSF in the circulation following production of bone marrow aplasia? Does the c-Mpl ligand account for all of the megakaryocyte stimulatory factors that have been described? Is there another factor that accounts for at least some of the acute alterations in megakaryocytopoiesis that occur immediately following a decrease in platelet levels? 相似文献
122.
123.
SV Singh PJ Benson X Hu A Pal H Xia SK Srivastava S Awasthi HA Zaren JL Orchard YC Awasthi 《Canadian Metallurgical Quarterly》1998,128(2):197-204
A commercial patient dose verification system utilizing non-invasive metal oxide semiconductor field effect transistor (MOSFET) dosimeters originally designed for radiotherapy applications has been evaluated for use at diagnostic energy levels. The system features multiple dosimeters that may be used to monitor entrance or exit skin dose and intracavity doses in phantoms in real time. We have characterized both the standard MOSFET dosimeter designed for radiotherapy dose verification and a newly developed "high sensitivity" MOSFET dosimeter designed for lower dose measurements. The sensitivity, linearity, angular response, post-exposure response, and physical characteristics were evaluated. The average sensitivity (free in air, including backscatter) of the radiotherapy MOSFET dosimeters ranged from 3.55 x 10(4) mV per C kg(-1) (9.2 mV R(-1)) to 4.87 x 10(4) mV per C kg(-1) (12.6 mV R(-1)) depending on the energy of the x-ray field. The sensitivity of the "high sensitivity" MOSFET dosimeters ranged from 1.15 x 10(5) mV per C kg(-1) (29.7 mV R(-1)) to 1.38 x 10(5) mV per C kg(-1) (35.7 mV R(-1)) depending on the energy of the x-ray field. The high sensitivity dosimeters demonstrated excellent linearity at high energies (90 and 120 kVp) and acceptable linearity at lower energies (60 kVp). The angular response was significant for free-in-air exposures, as illustrated by the sensitivity differences between the two sides of the dosimeter, but was excellent for measurements within a tissue equivalent cylinder. The post-exposure drift response is a complicated but reproducible function of time. Real-time monitoring requires little if any corrections for the post-exposure drift response. The MOSFET dosimeter system brings some unique capabilities to diagnostic radiology dosimetry including small size, real-time capabilities, nondestructive measurement, good linearity, and a predictable angular response. 相似文献
124.
125.
126.
127.
CY Spong SJ Lee SK McCune G Gibney DT Abebe R Alvero DE Brenneman JM Hill 《Canadian Metallurgical Quarterly》1999,140(2):917-924
Vasoactive intestinal peptide (VIP) is an important growth regulator of the embryonic day (E)9-E11 mouse. In comparably aged rat embryos, VIP messenger RNA (mRNA) is not detectable; however, peak concentrations of VIP in maternal rat serum indicate a nonembryonic source. In the current study, mouse maternal and embryonic tissues were examined from E6-E12. Although RT-PCR revealed VIP mRNA in E6-E7 conceptuses, by E8 (when extraembryonic tissues could be separated from the embryo), VIP mRNA was detected only in the decidua/trophoblast. Decidual/trophoblastic VIP mRNA decreased until E10, after which it was not detectable. VIP mRNA was not apparent in the embryo until E11-E12. At E9, VIP immunoreactivity was localized to abundant, diffuse cells in the decidua basalis, which were also immunoreactive for T cell markers. VIP binding sites were dense in the decidua/trophoblast at E6, but gradually decreased until E10, after which they were not apparent. VIP binding sites were detected in embryonic neuroepithelium by E9. The transient presence of VIP binding sites and mRNA in the decidua/trophoblast correlate with the critical period of VIP growth regulation, when VIP mRNA is absent in the embryo. These findings suggest that maternal lymphocytes are the source of VIP's regulating early postimplantation embryonic growth. 相似文献
128.
129.
130.