全文获取类型
收费全文 | 1634篇 |
免费 | 2篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 16篇 |
金属工艺 | 5篇 |
机械仪表 | 2篇 |
建筑科学 | 3篇 |
能源动力 | 1篇 |
轻工业 | 7篇 |
水利工程 | 1篇 |
无线电 | 4篇 |
一般工业技术 | 15篇 |
冶金工业 | 1566篇 |
原子能技术 | 4篇 |
自动化技术 | 10篇 |
出版年
2022年 | 2篇 |
2021年 | 1篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2013年 | 5篇 |
2012年 | 3篇 |
2011年 | 3篇 |
2010年 | 3篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2007年 | 3篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2001年 | 1篇 |
1999年 | 25篇 |
1998年 | 414篇 |
1997年 | 258篇 |
1996年 | 172篇 |
1995年 | 96篇 |
1994年 | 80篇 |
1993年 | 103篇 |
1992年 | 10篇 |
1991年 | 16篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 10篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 1篇 |
1983年 | 4篇 |
1982年 | 17篇 |
1981年 | 23篇 |
1980年 | 29篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 94篇 |
1976年 | 188篇 |
1975年 | 9篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1960年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1636条查询结果,搜索用时 15 毫秒
41.
C Reavill JP Hatcher VA Lewis GJ Sanger J Hagan 《Canadian Metallurgical Quarterly》1998,357(2-3):115-120
5-HT4 receptors are concentrated in areas of the brain which are rich in dopamine neuronal markers, which may suggest that they influence motor and reward processes. We tested this hypothesis by examining the effects of a 5-HT4 receptor antagonist, 8-amino-7-chloro-(N-butyl-4-piperidyl)methylbenzo-1,4-dioxan-5-car boxylate hydrochloride (SB-204070-A) on amphetamine- and nicotine-induced locomotor stimulation in intact rats. In rats with unilateral 6-hydroxydopamine-induced lesions of the ascending nigrostriatal dopaminergic projection, SB-204070-A was tested for its effects on amphetamine-induced rotation. SB-204070-A was also tested for its effects on rewarded behaviour maintained by intracranial self-stimulation. SB-204070-A did not alter behaviour under any of these conditions, suggesting a lack of involvement of the 5-HT4 receptor in motor and reward processes. 相似文献
42.
VA Verbenko 《Canadian Metallurgical Quarterly》1998,(5):126-129
Features were studied of brain organization of mental processes in schizophrenic patients during the period of aggravation of the condition, using methods common in neuropsychological diagnosis. Faulty mental functions are analyzed in connection with clinical manifestations. Groups have been identified of patients having particular neuropsychological and clinical characteristics. 相似文献
43.
44.
Oligonucleotide (ODN) directed triplex formation has therapeutic importance and depends on Hoogsteen hydrogen bonds between a duplex DNA and a third strand. While T*A:T triplets are formed at neutral pH, C+*G:C are favoured at acidic pH. Herein it is shown that 18-mer ODN containing spermine conjugated to 5-Me-dC at N4 (1-5), form triplexes with complementary 24-mer duplex 8:9 at neutral pH (7.3, 100 mM NaCl). Under such conditions, control ODN's carrying dC (6) or 5-Me-dC (7) did not show any triple helix formation. Remarkably, the triplexes from spermine-conjugates (1-5) have foremost stability at neutral pH (7.1), unlike the behavior of normal ODN's where optimal stability is at acidic pH (5.5). These results have importance in designing oligonucleotides for antigene applications. 相似文献
45.
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
46.
To clarify the mechanism of capsaicin-induced primary neuronal cell death, newborn and adult rats were given a subcutaneous injection of capsaicin (50 mg/kg). Neonatal capsaicin injection induced neuronal apoptosis in the trigeminal ganglion. Apoptotic neurons had peripheral stacks of long parallel endoplasmic reticulum that are characteristic to primary neurons of the B-type, and exhibited nucleoplasmic condensation, nuclear shrinkage and cytoplasmic fragmentation. Light microscopically, apoptotic neurons exhibited a sign of DNA fragmentation as revealed by a nick end labelling method. The proportion of apoptotic cells was quite low during the first 12 h after capsaicin injection (<1%), rapidly increase to 10.44% by 24 h, and decreased to 0.29% by 48 h. Normal and vehicle control levels of apoptosis were <1%. Nerve growth factor (NGF, 0.5 mg/kg) simultaneously administered with capsaicin reduced the incidence of apoptosis by about 35% at 24 h post-injection. Neonatal transection of the infraorbital nerve induced neuronal apoptosis similar to that produced by the neonatal capsaicin in the maxillary division of the trigeminal ganglion. Unlike capsaicin, however, the neurotomy-induced apoptosis was seen in neurons of both the A- and B-types. Neither the capsaicin injection nor the neurotomy induced apoptosis in adult rats, though mitochondrial swelling similar to that seen at 0.5 h after neonatal capsaicin was observed after capsaicin injection in adults. The results indicate that the capsaicin-induced and nerve injury-induced primary neuronal damages in newborn rats share a common final pathway, apoptosis. 相似文献
47.
VA Mamurov 《Canadian Metallurgical Quarterly》1998,(12):22-23
51 patients with Raynaud's disease has undergone prolonged normovolemic hemodilution (PNH) with a good effect. Disappearance of painful syndrome in 78.43% of cases, and a significant decrease of pains in 21.37% of cases was demonstrated. Complete healing of ulcero-necrotic defects of end phalanges of the hands was observed in 7 patients of 10 and partial--in 3. A significant remission of the disease in follow-up period was obtained. Thus, prolonged normovolemic hemodilution has resulted in significant improvement of short- and long-term results of treatment in patients with Raynaud's disease. 相似文献
48.
To determine the effect of life-long alcohol consumption on the adult and aged rat model, 4-week-old, female Sprague-Dawley rats were divided into three diet groups. Alcohol-treated animals were fed a modified Lieber-DeCarli diet ad libitum containing 35% ethanol-derived calories, whereas the pair-fed animals (weight-matched to ethanol rats) received an isocaloric liquid diet in which maltose-dextrin substituted calories supplied by ethanol. Chow animals were fed a standard rat chow ad libitum. Proximal tibiae (primarily cancellous bone) and femora (primarily cortical bone) were removed for analysis after 3, 6, 9, 12, or 18 months on the diets. Serum was collected for analysis of calcium levels, the calcium regulating hormones; parathyroid hormone, 25-hydroxyvitamin D, calcitonin, corticosterone, estradiol, testosterone, and IGF-1. Creatinine, SGOT/AST, and SGPT/ALT levels were measured to determine kidney and liver integrity. Previous studies, with young animals, showed that chronic alcohol consumption during the age of bone development reduced bone density and bone mass in both cortical and cancellous bone. The present study demonstrates that these reductions last throughout life, whereas morphological values, such as length and diameter, attain control levels. Calcium regulating hormones and sex hormones are essentially normal and do not appear to be the primary causative agent for adult alcohol-induced osteopenia, but it appears to be due to a more direct effect of alcohol on bone cells. 相似文献
49.
OBJECTIVES: The objectives of the study were to assess the suitability of a service for provision of emergency hormonal contraception by nurses. METHODS: Retrospective analysis was carried out of data obtained from the case records of 500 consecutive women who attended ABACUS (a city center-based family planning clinic in Liverpool, UK) for emergency contraception during the 7th and 9th months of the first year (1994) of the service. Similar data were collected for 100 consecutive women during 1 month of the third year (June 1996). The number of women who received emergency hormonal contraception was noted. In particular, details pertaining to the reasons for referral to the doctor and the trend of referrals were noted. RESULTS: The results indicate that during the first year the nurses independently issued emergency hormonal contraception to 37% of the women. They referred the remaining 63% to the medical staff. One-third of referrals were for ongoing contraception, especially oral contraception. Another third of referrals appeared to be due to 'nurse anxiety', as no medical or other cause was found for these referrals. During the third year, nurses dispensed emergency hormonal contraception to 64% of women. Among the remaining 36% of women who were referred to the doctor, 19% needed hormonal contraception. Referral reflecting 'nurse anxiety' significantly declined (1%) compared to the first year of service. CONCLUSIONS: Ongoing contraception, particularly initiation of oral contraception, was one of the main reasons for referral during the first year. Referral due to 'nurse anxiety' significantly declined with continued experience and may have reflected initial anxiety and the learning curve. With increased experience over the first 2 years, the outcome of this service showed encouraging improvement. The nurses now dispense emergency hormonal contraception to a majority of women. 相似文献
50.