全文获取类型
收费全文 | 300篇 |
免费 | 0篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 16篇 |
金属工艺 | 2篇 |
建筑科学 | 5篇 |
能源动力 | 4篇 |
轻工业 | 10篇 |
无线电 | 3篇 |
一般工业技术 | 7篇 |
冶金工业 | 245篇 |
自动化技术 | 7篇 |
出版年
2021年 | 1篇 |
2019年 | 1篇 |
2014年 | 2篇 |
2013年 | 4篇 |
2012年 | 2篇 |
2010年 | 3篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 11篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1998年 | 50篇 |
1997年 | 51篇 |
1996年 | 33篇 |
1995年 | 18篇 |
1994年 | 19篇 |
1993年 | 11篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 7篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1978年 | 1篇 |
1977年 | 8篇 |
1976年 | 21篇 |
1972年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有300条查询结果,搜索用时 602 毫秒
191.
A multicenter study of bispectral electroencephalogram analysis for monitoring anesthetic effect 总被引:1,自引:0,他引:1
PS Sebel E Lang IJ Rampil PF White R Cork M Jopling NT Smith PS Glass P Manberg 《Canadian Metallurgical Quarterly》1997,84(4):891-899
Occludin is the only known integral membrane protein localized at the points of membrane- membrane interaction of the tight junction. We have used the Xenopus embryo as an assay system to examine: (a) whether the expression of mutant occludin in embryos will disrupt the barrier function of tight junctions, and (b) whether there are signals within the occludin structure that are required for targeting to the sites of junctional interaction. mRNAs transcribed from a series of COOH-terminally truncated occludin mutants were microinjected into the antero-dorsal blastomere of eight-cell embryos. 8 h after injection, the full-length and the five COOH-terminally truncated proteins were all detected at tight junctions as defined by colocalization with both endogenous occludin and zonula occludens-1 demonstrating that exogenous occludin correctly targeted to the tight junction. Importantly, our data show that tight junctions containing four of the COOH-terminally truncated occludin proteins were leaky; the intercellular spaces between the apical cells were penetrated by sulfosuccinimidyl-6-(biotinamido) Hexanoate (NHS-LC-biotin). In contrast, embryos injected with mRNAs coding for the full-length, the least truncated, or the soluble COOH terminus remained impermeable to the NHS-LC-biotin tracer. The leakage induced by the mutant occludins could be rescued by coinjection with full-length occludin mRNA. Immunoprecipitation analysis of detergent-solubilized embryo membranes revealed that the exogenous occludin was bound to endogenous Xenopus occludin in vivo, indicating that occludin oligomerized during tight junction assembly. Our data demonstrate that the COOH terminus of occludin is required for the correct assembly of tight junction barrier function. We also provide evidence for the first time that occludin forms oligomers during the normal process of tight junction assembly. Our data suggest that mutant occludins target to the tight junction by virtue of their ability to oligomerize with full-length endogenous molecules. 相似文献
192.
193.
CA Peterson AH Bennett WJ Hellstrom FE Kaiser JE Morley KJ Nemo H Padma-Nathan VA Place JJ Prendergast PY Tam EA Tanagho LK Todd JC Varady N Gesundheit 《Canadian Metallurgical Quarterly》1998,159(5):1523-7; discussion 1527-8
PURPOSE: Transurethral alprostadil has been shown to be efficacious in many men with erectile dysfunction. We compared transurethral alprostadil and prazosin alone, and in combination to treat this disorder. MATERIALS AND METHODS: In this double-blind, placebo controlled study the erectile responses to transurethral alprostadil, prazosin and alprostadil-prazosin combinations were assessed in 234 men 26.8 to 81.5 years old with complete organic erectile dysfunction. Patients self-administered a random sequence of 7 doses in the clinic in 4 weeks. The erectile response was assessed using categorical and visual analog scales. RESULTS: Full penile enlargement or rigidity was achieved by 165 of the 234 men (70.5%) after at least 1 active dose of medication. The most effective alprostadil dose (500 microg.) resulted in full penile enlargement or rigidity in 51.8% of administrations, whereas the most effective prazosin dose (2,000 microg.) and placebo resulted in a similar response in 12.7 and 2.7%, respectively (p <0.001). The 500/2,000 microg. alprostadil/prazosin combination, which resulted in full enlargement or rigidity in 58.9% of doses, was only slightly better than the most effective dose of alprostadil alone (500 microg.). However, combinations of 125/500 and 250/500 microg. alprostadil/prazosin were more effective (p <0.01) than 125 and 250 microg. alprostadil given alone, respectively. The most common side effect of therapy was penile pain, which rarely led to study discontinuation. Hypotension most commonly developed at the higher alprostadil-prazosin combination. CONCLUSIONS: Transurethral alprostadil and alprostadil-prazosin combinations produced erections in men with complete organic erectile dysfunction. This combination therapy may be an option in patients who do not respond to transurethral alprostadil alone. 相似文献
194.
Neurotrophic factors profoundly affect neuronal differentiation, but whether they influence neuronal phenotype in instructive ways remains unclear: do different neurotrophic factors always trigger identical programs of differentiation or can each impose distinct functional properties even when acting upon the same population of target neurons? We addressed this issue by examining the regulatory effects of the four neurotrophins on the molecular components of electrical excitability, voltage-gated ion channels, within a single cellular context. Using patch clamp methods, we studied neurotrophin regulation of voltage-gated sodium, calcium, and potassium currents in SK-N-SH neuroblastoma cells. We found that each neurotrophin induced a unique pattern of expression of ionic currents despite similar activation of initial signal transduction events. Thus, each neurotrophin imposed a different excitable phenotype even when acting upon the same target cells. 相似文献
195.
A 1.8-kb NsiI-StuI fragment containing the recA gene of Xanthomonas campestris pv. campestris was cloned by a PCR-based approach and complementation of Escherichia coli HB 101. Sequence analysis of this fragment revealed an ORF (orf343) of 1,032 bp able to encode a protein of 343 amino acids with a calculated MW of 37,021 Da, a size similar to the values detected by in vitro system and Western blotting. It showed 69.6% identity to the E. coli RecA in amino acid sequence. Amino acid residues of the E coli RecA associated with functional activities are conserved in this Xc17 RecA. The recA mutant, L1, constructed by gene replacement, was sensitive to ultraviolet irradiation and methyl methanesulfonate, and deficient in homologous recombination. 相似文献
196.
NT Ktistakis 《Canadian Metallurgical Quarterly》1998,20(6):495-504
Sixty-seven insulinomas were investigated by immunohistochemistry using site-directed antibodies against insulin, proinsulin, chromogranin A, HISL-19, and four proteins directly or indirectly involved in the proteolytic processing of proinsulin: the prohormone convertases PC2 and PC3, carboxypeptidase H (CPH) and 7B2. Results were expressed in a six-grade score according to the frequency of immunoreactive tumour cells. Insulin was expressed by all tumours, appearing in either a diffuse or a polarized pattern and being detected in more than 30% of tumour cells in all cases but three. Proinsulin was also expressed in all tumours, with more than 50% of tumour cells immunoreactive in all cases but 5. It was consistently localized in the Golgi apparatus. In about half the cases, moreover, it also showed diffuse cytoplasmic staining, usually with a very sparse distribution. Trabecular and solid insulinomas did not present specific, homogeneous patterns of insulin immunostaining. However, insulin immunoreactivity was much more abundant in trabecular than in solid neoplasms, being present in virtually all tumour cells (score 6) in 50% and 8% of cases, respectively. Virtually all insulinomas expressed PC2, PC3, CPH and 7B2, usually in 30-100% of tumour cells, with a frequency significantly related to that of insulin. However, detection of PC2 and 7B2 was slightly less frequent than that of PC3 and CPH. In consecutive sections these proteins were found to be mostly co-localized with insulin and chromogranin A but not with proinsulin. They were heavily expressed in all 10 tumours with more than 10% of cells showing cytoplasmic proinsulin immunoreactivity, indicating that the leakage of proinsulin from the Golgi compartment is not associated with faulty expression of converting enzymes and possibly reflects a saturated processing capacity. HISL-19 immunoreactivity was found in both Golgi apparatus and insulin stores, indicating that the relevant antigen is different from all other proteins investigated. These results do not support a defect in expression or localization of proinsulin-processing enzymes in most insulinomas. 相似文献
197.
中原油田腐蚀之严重是其它油田无法比的,尤其是采油四厂南二线。最近,我们专门对此做了部分分析和研究,基本探明其原因,并做了相应的分析,提出了相应的对策以供参考。 相似文献
198.
EM Pacheco AC Civelek TK Natarajan SA D'Anna NT Iliff WR Green 《Canadian Metallurgical Quarterly》1997,115(9):1173-1177
OBJECTIVES: To report the histopathological and bone scan characteristics of the stages of hydroxyapatite fibrovascular integration and to consider the implications for the timing of peg drilling in a primate model. DESIGN: Three monkeys received hydroxyapatite implants covered only anteriorly with a fascia lata button to which the rectus muscles were sutured. Weekly bone scans were evaluated quantitatively and qualitatively. The orbits were harvested at 2, 4, and 8 weeks and examined histopathologically. RESULTS: Quantitatively, the implant's technetium uptake increased, then reached a plateau by 4 weeks. Peripheral uptake was present on the images and histologically at 2 weeks. When bone scan images suggested complete vascularization by the fourth week, the implant was 99% vascularized histologically. Completion of vascularization was ascertained at 8 weeks, without further discernible changes in the bone scans. CONCLUSIONS: The technetium bone scan is sensitive to the vascularization of the hydroxyapatite implant and discerns when complete vascularization is approached. This primate study models closely the clinical findings we have recently reported. We advocate at least a 4-week interval between the time the bone scan suggests full vascularization and peg drilling. 相似文献
199.
This study analyzes the involvement of men in abortion in Vietnam, where induced abortion is legal and abortion rates are among the highest in the world. Twenty men were interviewed in 1996 about the role they played in their wives' abortions and about their feelings and ethical views concerning the procedure. The results showed that both husbands and wives considered the husband to be the main decisionmaker regarding family size, which included the decision to have an abortion, but that, in fact, some women had undergone an abortion without consulting their husbands in advance. Parents and in-laws were usually not consulted; the couples thought they might object to the decision on moral grounds. Respondents' ethical perspectives on abortion are discussed. When faced with an unwanted pregnancy, the husbands adopted an ethics of care and responsibility toward family and children, although some felt that abortion was immoral. The study highlights the importance of understanding husbands' perspectives on their responsibilities and rights in reproductive decisionmaking and their ethical and other concerns related to abortion. 相似文献
200.