全文获取类型
收费全文 | 406篇 |
免费 | 1篇 |
专业分类
电工技术 | 1篇 |
综合类 | 4篇 |
化学工业 | 8篇 |
金属工艺 | 30篇 |
机械仪表 | 3篇 |
建筑科学 | 2篇 |
能源动力 | 1篇 |
轻工业 | 4篇 |
水利工程 | 2篇 |
无线电 | 4篇 |
一般工业技术 | 7篇 |
冶金工业 | 334篇 |
自动化技术 | 7篇 |
出版年
2022年 | 1篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2014年 | 3篇 |
2013年 | 7篇 |
2011年 | 5篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 5篇 |
2007年 | 6篇 |
2006年 | 1篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2003年 | 3篇 |
1999年 | 7篇 |
1998年 | 121篇 |
1997年 | 77篇 |
1996年 | 31篇 |
1995年 | 24篇 |
1994年 | 23篇 |
1993年 | 17篇 |
1992年 | 7篇 |
1991年 | 2篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1977年 | 7篇 |
1976年 | 20篇 |
1975年 | 3篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有407条查询结果,搜索用时 15 毫秒
401.
Premenstrual syndrome is a cyclical disorder involving behavioral, emotional, and physical symptoms during the premenstruum. Because of its unknown etiology, a variety of treatment options exist; yet no therapy has consistently reduced symptoms. Most recent advances have occurred in relaxation techniques and psychotropic therapies. 相似文献
402.
AM Zuckerman SE Mitchell AC Venbrux SO Trerotola SJ Savader GB Lund RI White FA Osterman 《Canadian Metallurgical Quarterly》1994,5(2):315-319
We investigated the mechanism of resistance in murine L1210 leukaemia cells selected after treatment with FCE 23762 methoxymorpholinyl doxorubicin: (MMRDX), a methoxymorpholinyl derivative of doxorubicin active in vitro and in vivo on multidrug-resistant (mdr) cells, currently undergoing phase I clinical trials. The resistant subline obtained after repeated in vitro treatments, L1210/MMRDX, is resistant in vitro and in vivo to all tested methoxymorpholinyl derivatives and to cyanomorpholinyl doxorubicin, but shows resistance to morpholinyl derivatives only in vivo or following their activation with rat S9-liver fractions in vitro. L1210/MMRDX cells are sensitive to classic mdr- and altered topoisomerase (AT)-mdr-associated drugs. These cells do not appear to overexpress the mdr1 gene, nor do they exhibit impaired intracellular drug accumulation and efflux or altered levels of glutathione and glutathione S-transferase. The extent of DNA single-strand break formation and, after microsomal activation, of DNA interstrand cross-links after treatment with MMRDX was similar in the parent and the resistant subline. The mechanism of resistance in L1210/MMRDX cells remains to be identified but may prove a novel one, highly specific for this class of mdr-active anthracyclines. 相似文献
403.
404.
405.
The authors found several common themes in intensive interviews with 20 prominent psychiatric administrators. The decision to go into administrative work resulted from strong interest in public service, frustration in other roles, and/or situational factors. Administration was learned by doing and by interaction with colleagues in the field or other knowledgeable individuals. The job of administrator is often perceived as stressful, but it offers rewards such as increased autonomy, opportunities for self-growth, prestige, and the potential for a broader contribution to mental health. 相似文献
406.
Globin biosynthesis was studied in both erythroid precursors and reticulocytes of three individuals with heterozygous alpha-thalassaemia. In contrast to the finding of equal or nearly equal alpha and beta chain synthesis in the marrow of patients with heterozygous beta-thalassaemia previously examined, our studies showed equal degrees of unbalanced globin synthesis in both reticulocytes and nucleated-erythroid cells of alpha-thalassaemia heterozygotes. Greater stability and less susceptibility to proteolysis of the excess beta-chain formed in alpha-thalassaemia may explain our findings. 相似文献
407.
本文从单基地雷达抗干扰的应用需求出发,分析了现有单基地雷达体制抗干扰的现状以及面临的困难.针对欺骗式干扰对抗的难题,提出了基于新体制波形分集阵雷达的抗主瓣方向欺骗式干扰思路,利用频率分集阵(Frequency Diverse Array,FDA)多输入多输出(Multiple-Input Multiple-Output,MIMO)雷达发射维自由度,实现真实目标和转发假目标在发射维度的区分,在部分先验知识的条件下,初步论证了FDA-MIMO雷达抗欺骗式干扰特别是主瓣欺骗式干扰的可行性.同时考虑转发式欺骗干扰在时间维的伪随机特性,提出了基于多假设检验的干扰样本挑选方法,大大提高了干扰协方差矩阵的估计性能.最后给出了FDA-MIMO雷达抗主瓣欺骗式干扰的分析与仿真结果. 相似文献