全文获取类型
收费全文 | 2783篇 |
免费 | 5篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 66篇 |
金属工艺 | 2篇 |
机械仪表 | 5篇 |
建筑科学 | 13篇 |
能源动力 | 6篇 |
轻工业 | 42篇 |
水利工程 | 1篇 |
无线电 | 28篇 |
一般工业技术 | 42篇 |
冶金工业 | 2541篇 |
自动化技术 | 41篇 |
出版年
2022年 | 8篇 |
2021年 | 6篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 7篇 |
2016年 | 8篇 |
2015年 | 2篇 |
2014年 | 7篇 |
2013年 | 5篇 |
2012年 | 12篇 |
2011年 | 17篇 |
2010年 | 16篇 |
2009年 | 15篇 |
2008年 | 23篇 |
2007年 | 17篇 |
2006年 | 14篇 |
2005年 | 8篇 |
2004年 | 10篇 |
2003年 | 16篇 |
2002年 | 8篇 |
2001年 | 8篇 |
2000年 | 10篇 |
1999年 | 88篇 |
1998年 | 753篇 |
1997年 | 461篇 |
1996年 | 289篇 |
1995年 | 162篇 |
1994年 | 136篇 |
1993年 | 156篇 |
1992年 | 16篇 |
1991年 | 29篇 |
1990年 | 30篇 |
1989年 | 37篇 |
1988年 | 25篇 |
1987年 | 20篇 |
1986年 | 22篇 |
1985年 | 21篇 |
1984年 | 2篇 |
1983年 | 10篇 |
1982年 | 16篇 |
1981年 | 9篇 |
1980年 | 28篇 |
1979年 | 4篇 |
1978年 | 13篇 |
1977年 | 64篇 |
1976年 | 157篇 |
1975年 | 5篇 |
1974年 | 2篇 |
1972年 | 2篇 |
排序方式: 共有2789条查询结果,搜索用时 15 毫秒
31.
Acute challenge with clozapine and haloperidol produce different anatomical patterns of c-fos expression in the forebrain. The pharmacological profile of atypical antipsychotics suggests that serotonin might contribute to the unique therapeutic benefits of these drugs. In order to test this possibility, we examined the abilities of 5-HT1A and 5-HT2A/2c agonists to modify the pattern of c-fos expression induced by haloperidol and clozapine. Various groups of rats were pretreated with either saline, DOI, 8-OH-DPAT, and 8-OH-DPAT + DOI 30 min prior to haloperidol or clozapine administration. Rats were killed 90 min after antipsychotic administration. In saline-pretreated rats, haloperidol produced intense Fos-LI in all four striatal quadrants while the effect of clozapine was restricted to the medial part of the striatum. Prior administration of 8-OH-DPAT significantly reduced haloperidol-induced Fos-LI in all four striatal quadrants while DOI and 8-OHDPAT + DOI significantly reduced Fos-LI only in dorso- and ventrolateral quadrants. In the nucleus accumbens, haloperidol induced intense Fos-LI in the core and the shell regions whereas clozapine induced c-fos expression only in the shell. Pretreatment with 8-OHDPAT in haloperidol treated rats reduced Fos-LI in the core region yielding to a c-fos pattern similar to that induced by clozapine. In the prefrontal cortex of saline-pretreated rats, haloperidol produced a moderate c-fos expression compared with the intense expression produced by clozapine. Pretreatment with serotonin agonists before haloperidol brought the number of FOS-positive neurons to the same level as in clozapine treated rats. These results show the ability of 5-HT agonists to transform the typical pattern of c-fos expression induced by haloperidol into a pattern resembling that of clozapine. 相似文献
32.
This article focuses on neuroendocrine measures in anxiety disorders and their relationships to neurotransmitter and neuroendocrine function. In particular, the hypothalamic-pituitary-somatotropin and the hypothalamic-pituitary-adrenal (HPA) axes are emphasized, and a role for extrahypothalamic corticotropin releasing factor is proposed. Additional neuroactive hormones are also considered. A nonhuman primate model of anxiety is discussed in terms of its neuroendocrine relevance. And, throughout, a hypothetical functional-anatomic model for anxiety and panic is proposed using the findings of cognitive neuroscience fear research. Finally, an effort is made to synthesize existing psychoneuroendocrinologic data into a current conceptualization of the pathophysiology of anxiety disorders. 相似文献
33.
GM Martin 《Canadian Metallurgical Quarterly》1998,10(2):148-149
We present a case of a patient who is HIV positive and developed both thrombotic thrombocytopenia purpura and visceral Kaposi's sarcoma (KS) with hemorrhage. This case presents a difficult management problem in that the patient's bleeding originated from KS lesions and did not quickly abate with plasmapheresis therapy despite both clinical and laboratory improvement after 2-4 days. Chemotherapy was initiated on day 13 and the patient's condition improved markedly afterward. We believe the addition of chemotherapy to plasmapheresis hastened the improvement of our patient's thrombotic thrombocytopenic purpura (TTP) and KS-related bleeding. Therefore, under similar conditions, we recommend combining plasmapheresis and chemotherapy at the onset of therapy. 相似文献
34.
Prevention of T cell anergy by signaling through the gamma c chain of the IL-2 receptor 总被引:1,自引:0,他引:1
VA Boussiotis DL Barber T Nakarai GJ Freeman JG Gribben GM Bernstein AD D'Andrea J Ritz LM Nadler 《Canadian Metallurgical Quarterly》1994,266(5187):1039-1042
When stimulated through their antigen receptor without requisite costimulation, T cells enter a state of antigen-specific unresponsiveness termed anergy. In this study, signaling through the common gamma chain of the interleukin-2 (IL-2), IL-4, and IL-7 receptors in the presence of antigen was found to be sufficient to prevent the induction of anergy. After culture with IL-2, IL-4, or IL-7, Jak3 kinase was tyrosine-phosphorylated, which correlated with the prevention of anergy. Therefore, a signal through the common gamma chain may regulate the decision of T cells to either clonally expand or enter a state of anergy. 相似文献
35.
the SL transmission terminal equipment (TTE) provides the interface between the inland toll transmission network at 139.264 Mbit/s (CCITT 4th level) and the SL undersea cable on a two working and one standby fiber-pair basis. The TTE provides multiplexing of two 139.264- Mbit/s signal and overhead bits per fiber as well as electrical-to-optical signal conversion. End-to-end maintenance features, such as, order-wire, line performance parameters, alarms, and line regenerator supervisory signaling access are also provided. 相似文献
36.
37.
The first isolated case of agenesis of the mastoid antrum, previously only described in association with the congenital syndromes trisomy 13 and mandibulofacial dysostosis, is reported. The loss of this important surgical landmark may result in disorientation and iatrogenic trauma. The surgeon must be aware of its existence, and where it is suspected the middle fossa dura should be exposed and followed posteriorly until the lateral sinus is encountered. 相似文献
38.
39.
A method has been developed for determining sterigmatocystin in yellow and white corn, barley, oats, rye, sorghum, brown and wild rice, and soybeans. A partition column packed with activated magnesium silicate was used for cleanup. Averaged recoveries are 104% in white corn, 114% in rye, 100% in oats, 134% in brown rice, 96% in barley, 105% in sorghum and wild rice, and 92% in soybeans. The limit of sensitivity is 50 mug/kg for any of these commodities. 相似文献
40.