全文获取类型
收费全文 | 48篇 |
免费 | 0篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 4篇 |
建筑科学 | 6篇 |
能源动力 | 1篇 |
轻工业 | 4篇 |
无线电 | 2篇 |
一般工业技术 | 4篇 |
冶金工业 | 22篇 |
原子能技术 | 2篇 |
自动化技术 | 1篇 |
出版年
2011年 | 1篇 |
2010年 | 1篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2006年 | 1篇 |
2004年 | 2篇 |
2002年 | 2篇 |
2001年 | 2篇 |
1998年 | 7篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1964年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有48条查询结果,搜索用时 15 毫秒
1.
The present study characterised seven species of the Chabertiidae (Nematoda: Strongyloidea) belonging to either the subfamily Oesophagostominae (Oesophagostomum radiatum, Oesophagostomum venulosum, Oesophagostomum dentatum, Oesophagostomum quadrispinulatum, Oesophagostomum columbianum, Oesophagostomum bifurcum) or to the subfamily Chabertiinae (Chabertia ovina) by their second internal transcribed spacer rDNA sequence, assessed the extent of intraspecific variation and interspecific differences in the sequence, and inferred the phylogenetic relationship of C. ovina with respect to members of the Oesophagostominae. In both the phenetic and cladistic analyses of the sequence data, Chabertia was nested within Oesophagostomum, suggesting either that the species examined represent members of the same genus, or alternatively, that Oesophagostomum may represent more than one genus. 相似文献
2.
Soil transformation of 2(3H)-benzoxazolone of rye into phytotoxic 2-amino-3H-phenoxazin-3-one 总被引:4,自引:0,他引:4
Nonsterile soil transforms the rye metabolite 2(3H)-benzoxazolone (BOA) into 2-amino-3H-phenoxazin-3-one, which is an order
of magnitude more toxic to barnyard grass than benzoxazolone. Benzoxazolone was recovered unchanged from sterile soil. However,o-aminophenol is converted to aminophenoxazinone by both sterile and nonsterile soil in the presence of air. Aminophenoxazinone
is probably produced by microbial hydrolysis of benzoxazolone intoo-aminophenol, which is oxidized to aminophenoxazinone in both sterile and nonsterile soil. No 2,2′-oxo-1,1′-azobenzene was
found in any incubations of soil with benzoxazolone,o-aminophenol, oro-azophenol. 相似文献
3.
M Frank-Stromborg LJ Wassner M Nelson B Chilton BE Wholeben 《Canadian Metallurgical Quarterly》1998,13(4):231-241
Not only the ovarian steroids but a number of proteins have an effect on the endometrium and its capability to accept an implanting embryo and to establish a pregnancy. In this study we have selected the placental protein 14 (PP14) which is, in spite of its name, produced by the glandular epithelium of the endometrium. Pregnancy-specific beta 1-glycoprotein (SP1) was also investigated. This marker is trophoblast-specific but it has been chosen since some patients repeatedly exhibit weak but detectable serum SP1 when no embryo is present. There seems to be a negative correlation between the chance of obtaining a pregnancy and the occurrence of such abnormal serum SP1 signals; they could originate from the endometrium itself or from another maternal source influencing the endometrium indirectly. The full-cycle time course was determined for these two proteins as well as for estradiol and progesterone. A total of 66 cycles were analyzed, of which 16 were from ovulating volunteers without any hormonal treatment (controls) and 13 were from women taking oral contraceptives. The remaining 37 cycles were from 32 patients undergoing conventional in vitro fertilization (IVF) treatment. Eight pregnancies were achieved in this group during the study period. We found that abnormal positive SP1 signals occurred predominantly in the unsuccessful IVF subgroup, but also in the control groups (with or without contraceptive pills), and this in a cycle-independent manner. PP14, on the other hand, exhibited cyclic patterns in the IVF and ovulating control cycles as did progesterone. However, in seven out of 13 cycles under oral contraception (and suppressed progesterone), a midcycle rise in PP14 was observed. Moreover, midcycle PP14 levels were generally higher in this group when compared to the ovulating controls as well as to the cycles under controlled ovarian stimulation for IVF. This confirms that PP14 is influenced by progesterone but only in an indirect way or under the additional effect of other hormones. It is unlikely that SP1 plays this role since it was not correlated to any of the other proteins or steroids studied. Nevertheless, SP1 did not occur randomly over the different groups. 相似文献
4.
Biosynthetic requirements for the repair of membrane damage in pressure-treated Escherichia coli. 总被引:1,自引:0,他引:1
P Chilton N S Isaacs P Manias B M Mackey 《International journal of food microbiology》2001,71(1):101-104
Cells of Escherichia coli that survived pressure treatment at 400 MPa showed increased sensitivity to sodium deoxycholate or sodium chloride in the plating medium, implying that homeostatic or barrier functions associated with outer and cytoplasmic membranes, respectively, were impaired. Repair of such sublethal membrane damage occurred when cells were incubated at 37 degrees C in tryptone soya broth. Inhibitor studies indicated that repair of cytoplasmic membrane damage was energy-dependent and required RNA and protein synthesis, whereas repair of outer membrane damage occurred with no requirement for energy or RNA or protein synthesis. 相似文献
5.
6.
In the last few years, it has become increasingly apparent that the biochemistry of PAF (platelet-activating factor) and that
of arachidonic acid are interrelated in a number of inflammatory cells. Experiments presented here further point out that
arachidonic acid plays a crucial role in the catabolism and biosynthesis of PAF. In addition, they suggest that the same phospholipid
molecular species may serve as a source for both arachidonic acid and 1-alkyl-2-lyso-sn-glycero-3-phosphocholine during cell activation. Finally, they reveal that there may be common regulatory mechanisms for
the biosynthesis of PAF and arachidonic acid metabolites. Taken together, studies examining the relationship between PAF and
arachidonic acid suggest it may be difficult to consider the biochemistry of PAF without considering arachidonic acid metabolism
and vice versa.
Based on a paper presented at the Third International Conference on Platelet-Activating Factor and Structurally Related Alkyl
Ether Lipids, Tokyo, Japan, May 1989. This is Publication No. 014 from the Johns Hopkins Asthma & Allergy Center, 301 Bayview
Boulevard, Baltimore, MD 21224. 相似文献
7.
D Do R Marcus V Froelicher A Janosi J West JE Atwood J Myers R Chilton J Froning 《Canadian Metallurgical Quarterly》1998,114(5):1437-1445
Currently the standard exercise test is shifting from being a tool for the cardiologist to utilization by the nonspecialist. This change could be facilitated by computerization similar to the interpretation programs available for the resting ECG. Therefore, we sought to determine if computerization of both exercise ECG measurements and prediction equations can substitute for visual analysis performed by cardiologists to predict which patients have severe angiographic coronary artery disease. We performed a retrospective analysis of consecutive patients referred for evaluation of possible or known coronary artery disease who underwent both exercise testing with digital recording of their exercise ECGs and coronary angiography at two university-affiliated Veteran's Affairs medical centers and a Hungarian hospital. There were 2,385 consecutive male patients with complete data who had exercise tests between 1987 and 1997. Measurements included clinical and exercise test data, and visual interpretation of the ECG paper tracings and > 100 computed measurements from the digitized ECG recordings and compilation of angiographic data from clinical reports. The computer measurements had similar diagnostic power compared with visual interpretation. Computerized ECG measurements from maximal exercise or recovery were equivalent or superior to all other measurements. Prediction equations applied by computer were only able to correctly classify two or three more patients out of 100 tested than ECG measurements alone. beta-Blockers had no effect on test characteristics while ST depression on the resting ECG decreased specificity. By setting probability limits using the scores from the equations, the population was divided into high-, intermediate-, and low-probability groups. A strategy using further testing in the intermediate group resulted in 86% sensitivity and 85% specificity for identifying patients with severe coronary disease. We conclude that computerized exercise ST measurements are comparable to visual ST measurements by a cardiologist and computerized scores only minimally improved the discriminatory power of the test. However, using these scores in a stratification algorithm allows the nonspecialist physician to improve the discriminatory characteristics of the standard exercise test even when resting ST depression is present. Computerization permitted accurate identification of patients with severe coronary disease who require referral. 相似文献
8.
The finite difference time domain (FDTD) method is a common, robust simulation technique for transient electromagnetic interactions with complicated structures. However, the standard FDTD method is limited to cartesian grids everywhere in the computational grid. Many practitioners have extended FDTD to handle multiresolution problems by using finer grids near structures with small geometrical features abutted to coarse grids in regions of empty space. Unfortunately, subgridding implementations based on interpolation or extrapolation of neighboring field values can exhibit late time instabilities. Herein, a subgridding method based on multigrid finite element principles will be developed and its stability proven. Numerical results will assess its performance in 2-D and 3-D. 相似文献
9.
Soil transformation of wheat and corn metabolites mboa and DIM2BOA into aminophenoxazinones 总被引:2,自引:0,他引:2
Praveen Kumar Ronald W. Gagliardo William Scott Chilton 《Journal of chemical ecology》1993,19(11):2453-2461
The defensive cyclic hydroxamates 7-methoxy-2,4-dihydroxy-1,4(2H)-benzoxazin-3-one (DIMBOA) and 7,8-dimethoxy-2,4-dihydroxy-1,4(2H)-benzoxazin-3-one (DIM2BOA) of wheat and corn are transformed in nonsterile soil, via 6-methoxy-2(3H)-benzoxazolone (MBOA) and 6,7-dimethoxy-2(3H)-benzoxazolone (M2BOA) respectively, into 2-amino-7-methoxy-3H-phenoxazin-3-one and 2-amino-4,6,7-trimethoxy-3H-phenoxazin-3-one. The soil transformation is similar of that undergone by the rye metabolite 2(3H)-benzoxazolone (BOA) into 2-amino-3H-phenoxazin-3-one. The transformations to phenoxazinones are not observed in sterile soil. The 2-amino-3H-phenoxazin-3-one inhibits barnyard grass radicle elongation, but the methoxylated aminophenoxazinones are not significantly inhibitory. 相似文献
10.