全文获取类型
收费全文 | 719篇 |
免费 | 1篇 |
专业分类
电工技术 | 1篇 |
综合类 | 1篇 |
化学工业 | 53篇 |
金属工艺 | 10篇 |
机械仪表 | 8篇 |
矿业工程 | 3篇 |
轻工业 | 5篇 |
水利工程 | 1篇 |
石油天然气 | 29篇 |
无线电 | 8篇 |
一般工业技术 | 17篇 |
冶金工业 | 570篇 |
原子能技术 | 6篇 |
自动化技术 | 8篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2018年 | 9篇 |
2017年 | 5篇 |
2016年 | 8篇 |
2015年 | 4篇 |
2014年 | 3篇 |
2013年 | 3篇 |
2012年 | 5篇 |
2011年 | 3篇 |
2010年 | 4篇 |
2009年 | 4篇 |
2008年 | 3篇 |
2007年 | 11篇 |
2006年 | 6篇 |
2005年 | 4篇 |
2004年 | 5篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 20篇 |
1998年 | 151篇 |
1997年 | 120篇 |
1996年 | 63篇 |
1995年 | 45篇 |
1994年 | 35篇 |
1993年 | 26篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 30篇 |
1976年 | 32篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1971年 | 3篇 |
1969年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有720条查询结果,搜索用时 15 毫秒
1.
IS Grewal P Borrow EG Pamer MB Oldstone RA Flavell 《Canadian Metallurgical Quarterly》1997,9(4):491-497
Research in the past few years has documented significant advances in our understanding of the CD40-CD40 ligand (CD154) system in diverse immune functions. This system influences many T cell mediated inflammatory immune responses and effector functions, unmasking a previously unexpected role for CD40-CD154 in cell mediated immunity. Manipulation of CD154 in animal models of infection by the use of CD154-deficient mice or anti-CD154 antibodies has shown the importance of this system in the initiation of the inflammatory response, in the activation of antigen-presenting cells and in resistance to infections. 相似文献
2.
SV Varha OH Reznikov IS Turchyn VM Demchenko OP Potikha PV Sinitsyn LV Tarasenko LV Cha?kovs'ka 《Canadian Metallurgical Quarterly》1994,40(5-6):105-109
The effect exerted by transplantation of the 5 day culture of testicles from newly born piglets on the hypogonadal state of mature X-ray irradiated (3 Gy) rats was studied. It has been found that a month after transplantation (two months after irradiation) the hypogonadal state disappeared for a while, which is confirmed by normalization of the weight of seminal vesicles, content of testosterone and biologically active lutropine, restoration of the reproductive function of rats. No significant changes in steroidogenesis activity have been found, which proves a substituent character of transplantation. The effect disappears three months later but certain restoration of the content of nucleic acids in the testicles is observed. 相似文献
3.
AS Astapchik EP Podvoisky IS Chebotko BM Khusid AG Merzhanov BB Khina 《Canadian Metallurgical Quarterly》1993,47(1):319-326
The labile protons of two 32-base-pair, four-arm models of immobile Holliday junctions have been studied by two-dimensional 1H nuclear magnetic resonance (NMR) spectroscopy. Overlap of resonances in the imino-imino region of two-dimensional nuclear Overhauser enhancement (NOE) spectra necessitates the use of a multi-pathway approach for obtaining sequence-specific assignments wherein all possible NOE connectivities to the labile protons are utilized, including those from the 2H of adenine, 5CH3 of thymine, and 5H of cytosine. Resonance assignments are obtained for all slowly exchanging imino and cytosine amino protons. Base-pairing up to and including the junction point is found in all four arms of both Holliday junctions. Several cross-arm NOE connectivities are identified and can be used to infer the geometry of the helical stacking domains. The two Holliday junctions studied, which differ only by the exchange of two base pairs at the branch point, appear to have opposite arm stacking geometries. These assignments form an important part of the critical background for detailed NMR analysis of Holliday junction structure and dynamics. 相似文献
4.
EA Ismail IS Shabani M Badawi H Sanaa S Madi A Al-Tawari H Nadi M Zaki Q Al-saleh 《Canadian Metallurgical Quarterly》1998,13(10):488-492
We studied Guillain-Barré syndrome, affecting children 12 years old or less, throughout Kuwait, in the period between January 1, 1992, and March 31, 1997. Nineteen children had the diagnostic criteria of Guillain-Barré syndrome, with an overall annual incidence rate of 0.95/100,000 population at risk. Female patients outnumbered male patients with a sex ratio of 1.4:1. There was a clustering of cases in winter and spring and in the year 1996. The disease symptoms were relatively severe in our patients because only 16% (3 of 19) of them were able to walk at the height of their illness, whereas the rest were bed or chair bound or needed assisted ventilation. Two patients had the electrodiagnostic features of axonal neuropathy and both had residual deficits on follow-up, whereas the rest recovered fully. All the patients received intravenous immunoglobulin. The mean time to walk unaided was 23.5 days (range, 2-84 days) after intravenous immunoglobulin and excluding the two patients with axonal neuropathy, and full recovery was achieved in a mean time of 103 days (range, 30-300 days). Contrary to previous studies, we found no correlation between oral polio vaccine administration and Guillain-Barré syndrome in 2 successive years (1995 and 1996) during a nationwide campaign targeting children less than 5 years old. 相似文献
5.
A mathematical model of complex heat exchange in the flame space of the melting zone of a regenerative bath furnace for sheet glass is presented. The calculated temperature fields in the gas space and on the internal surface of the roof, fields of the density of heat absorption by the surface of the pool. and consumption components in the heat balance of the furnace indicate the possibility of using the model for detailed analysis and prediction of its thermal operation.Translated from Steklo i Keramika, No. 3–5, May, 1996. 相似文献
6.
Arylsulfate sulfotransferase purified from Eubacterium A-44 has higher specific activity than the enzymes from Klebsiella K-36 and Haemophilus K-12. Propylparaben and butylparaben were good substrates among several parabens. The antibacterial activity of parabens was reduced by the sulfation of the phenolic hydroxy group. Tyrosine-containing peptides, kyotorphin, enkephalin and cholecystokinin non-sulfate, were effective as acceptor substrates by A-44, K-36 and K-12 sulfotransferases. 相似文献
7.
p53 mutations, a tumor suppressor gene located on chromosome 17p, are the most common genetic alterations found in human cancers. Although the p53 expression or mutation has been investigated in a variety of cancers there have been very few studies in extrahepatic bile duct cancers. In this study, we investigated the immunohistochemical expression of p53 in formalin fixed paraffin embedded archival specimens of 36 extrahepatic bile duct cancers in which p53 expression was found in eighteen (50%) cases. There was no significant difference in age, gender, size of tumor, histologic grade, extent of tumor involvement, lymph node metastasis and tumor resectability according to p53 immunoreactivity. Comparison of survival duration according to p53 expression showed no significant difference. In conclusion, we reported 50 percent of p53 expression in extrahepatic bile duct cancers by immunohistochemical staining and we found no prognostic significance of p53 expression in dinicopathologic parameters. 相似文献
8.
IS Han N Ramamurthy JH Yun U Schaller ME Meyerhoff VC Yang 《Canadian Metallurgical Quarterly》1996,10(14):1621-1626
A novel method to monitor specific peptidase activities in biological samples as complex as undiluted plasma/blood is described. The approach is based on the design of synthetic polypeptide substrates in which di- or triarginine sequences are linked to each other via one or more other amino acids recognized specifically by the peptidase to be determined. Detection of chymotrypsin and renin activities using synthetic substrates P4 (F-R-R-R-F-V-R-R-F-NH2) and P5 (R-R-R-L-L-R-R-L-L-R-R-R), respectively, serves to demonstrate the principles of this new assay system. A polyion-sensitive membrane electrode, prepared by doping polymer films with dinonylnaphthalene-sulfonate (DNNS), is shown to exhibit significant nonequilibrium electromotive force (EMF) responses toward these and other polycationic substrates at microgram/milliliter levels under physiological conditions. The same electrode, however, exhibits much smaller total EMF response toward the shorter fragments of the synthetic peptides generated by peptidase activity; hence, the addition of peptidase to a solution containing the synthetic substrate yields a change in electrode EMF response, the rate of which is proportional to the activity of peptidase present. Other synthetic polycationic peptides as well as natural polycationic peptides (e.g., protamine) that lack specific cleavage sites for chymotrypsin and renin, yet are detected by the DNNS-based membrane electrode, do not elicit any significant change in EMF response in the presence of the peptidases, confirming the feasibility and utility of the proposed bioanalytical method. 相似文献
9.
The results of a thermal engineering analysis of a bath furnace heated by natural gas with the surface area of the melting part equal to 303.3 m2 and equipped with six pairs of burners are presented. Practical recommendations are given for increasing the efficiency of the furnace. The data can be used for developing a mathematical model of heat transfer in a glass furnace.Translated from Steklo i Keramika, No. 3, pp. 9–11, March, 1996. 相似文献
10.
For viruses made of nucleic acid and protein, the structure of the protein outer shell has, in the past, been found to be uniquely determined by the viral genome. However, here, non-denaturing agarose gel electrophoresis of bacteriophage T7 reveals two states of the mature T7 capsid; the conditions of growth are found to alter the population by T7 of these two electrophoretically defined states. Both states have been previously observed for a genetically altered T7 and they are observed here for wild-type T7. The average electrical surface charge density of a bacteriophage particle (delta) determines its state; the delta of particles in both states is negative. For a given condition of growth, the population of these two states is influenced by the extent to which the major T7 outer shell protein, p10A, is accompanied by its minor readthrough variant, p10B. Comparison of the two electrophoretic states reveals the following. (1) No difference in radius is present in the outer shell (+/-2%). (2) As the pH of electrophoresis is either increased or decreased from neutrality, the state becomes more highly populated for which delta is greater in magnitude (state 1). By changing the pH, some T7 particles are made to change state. (3) Particles in state 1 adsorb less quickly to host cells than do the particles in the alternative state (state 2). This latter observation suggests the hypothesis that state 1 evolved to reduce the probability of re-initiating an infection when conditions are not favorable for growth. This hypothesis is supported by the observation that, as conditions of growth become apparently more unfavorable, progeny increasingly populate state 1. 相似文献