全文获取类型
收费全文 | 1926篇 |
免费 | 8篇 |
专业分类
电工技术 | 2篇 |
综合类 | 54篇 |
化学工业 | 103篇 |
金属工艺 | 10篇 |
机械仪表 | 6篇 |
建筑科学 | 46篇 |
能源动力 | 5篇 |
轻工业 | 44篇 |
水利工程 | 2篇 |
无线电 | 8篇 |
一般工业技术 | 49篇 |
冶金工业 | 1541篇 |
原子能技术 | 6篇 |
自动化技术 | 58篇 |
出版年
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 3篇 |
2020年 | 8篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 3篇 |
2015年 | 16篇 |
2014年 | 22篇 |
2013年 | 23篇 |
2012年 | 18篇 |
2011年 | 22篇 |
2010年 | 27篇 |
2009年 | 20篇 |
2008年 | 27篇 |
2007年 | 18篇 |
2006年 | 19篇 |
2005年 | 11篇 |
2004年 | 12篇 |
2003年 | 15篇 |
2002年 | 9篇 |
2001年 | 10篇 |
2000年 | 3篇 |
1999年 | 43篇 |
1998年 | 416篇 |
1997年 | 259篇 |
1996年 | 160篇 |
1995年 | 116篇 |
1994年 | 93篇 |
1993年 | 105篇 |
1992年 | 16篇 |
1991年 | 28篇 |
1990年 | 31篇 |
1989年 | 35篇 |
1988年 | 31篇 |
1987年 | 30篇 |
1986年 | 21篇 |
1985年 | 18篇 |
1983年 | 8篇 |
1982年 | 11篇 |
1981年 | 10篇 |
1980年 | 13篇 |
1979年 | 3篇 |
1978年 | 8篇 |
1977年 | 34篇 |
1976年 | 94篇 |
1974年 | 4篇 |
1966年 | 3篇 |
1957年 | 4篇 |
1952年 | 3篇 |
排序方式: 共有1934条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
Specific brain receptors for oxytocin have been described in several mammalian species. The distribution of these receptors differs greatly across species and in the rat, receptor binding in specific brain regions appears to depend upon gonadal steroids. This study used in vitro receptor autoradiography to examine the effects of testosterone on oxytocin receptor binding in the mouse forebrain. Three groups of male mice were compared: castrates treated with blank capsules, castrates treated with testosterone filled capsules, and intact males. Irrespective of steroid treatment, the distribution of oxytocin receptors in mouse forebrain differed markedly from patterns previously described in the rat. In addition to these species differences in receptor distribution, testosterone had effects in the mouse which differed from the induction of receptors previously reported in the rat. In the mouse ventromedial nucleus of the hypothalamus, binding in the untreated castrate males was approximately double that observed in either the intact or the testosterone-treated castrates. In other regions of the mouse brain, such as the intermediate zone of the lateral septum, binding to oxytocin receptors was increased with testosterone treatment. These results suggest that the brain oxytocin receptor varies across species not only in its distribution but also in its regional regulation by gonadal steroids. These apparently paradoxical changes in oxytocin receptor binding may result from either direct or indirect effects of gonadal steroids in mouse brain. 相似文献
6.
7.
8.
9.
Isoforms p69 and p100 of 2'',5''-oligoadenylate synthetase induced differentially by interferons in vivo and in vitro 总被引:1,自引:0,他引:1
PL Witt I Marié N Robert A Irizarry EC Borden AG Hovanessian 《Canadian Metallurgical Quarterly》1993,13(1):17-23
There is no better place to test life-saving resuscitation interventions than in the prehospital setting. Patients rarely survive cardiac arrest if resuscitation techniques have failed before leaving the scene. Also, paramedics are usually very experienced in key initial resuscitative techniques, and they routinely operate under strict paramilitary protocol, resulting in better study compliance. In addition, the large study populations that are derived from emergency medical services (EMS) systems lead to faster study completion and statistically stronger data. Most important, by reinforcing standardized care, rigidly scrutinized trials improve patient care, regardless of the effect of the study intervention. The success of productive EMS research centers requires routine communication between hospital and EMS administrators and their medical directors, designation of mutually acceptable data collectors who guarantee confidentiality, reciprocal exchange of study data provided as educational seminars to the hospitals, commitments to support the budget requests of an EMS program and appropriate system modifications, inclusion of EMS personnel in study design from the very beginning, prospective education of the medical community and media before protocol implementation, an authoritative grassroots medical director, and a paramedic supervisor system. 相似文献
10.
Recently published studies indicate a potential clinical application of PET in head and neck tumors. In the preoperative staging phase, PET enables confirmation of regional lymph node extension and guides nodal neck dissection or systemic treatment. In this phase, a high negative predictive value, near 100%, could make it possible to avoid many negative neck dissections. This is a reliable technique for confirming or excluding the presence of recurrent/residual tumor and for obtaining an early evaluation of chemotherapeutic and radiotherapeutic response. PET imaging in many cases makes it possible to locate and guide histological study of tumors with an unknown primary. PET imaging for these indications is a perfect complementary method for clinical exploration and better than other imaging techniques. 相似文献