全文获取类型
收费全文 | 726篇 |
免费 | 19篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 18篇 |
化学工业 | 75篇 |
金属工艺 | 9篇 |
机械仪表 | 12篇 |
建筑科学 | 35篇 |
矿业工程 | 1篇 |
能源动力 | 27篇 |
轻工业 | 42篇 |
水利工程 | 4篇 |
无线电 | 80篇 |
一般工业技术 | 114篇 |
冶金工业 | 255篇 |
原子能技术 | 8篇 |
自动化技术 | 67篇 |
出版年
2022年 | 4篇 |
2021年 | 12篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 9篇 |
2017年 | 15篇 |
2016年 | 6篇 |
2015年 | 5篇 |
2014年 | 10篇 |
2013年 | 24篇 |
2012年 | 24篇 |
2011年 | 27篇 |
2010年 | 24篇 |
2009年 | 20篇 |
2008年 | 33篇 |
2007年 | 39篇 |
2006年 | 18篇 |
2005年 | 19篇 |
2004年 | 26篇 |
2003年 | 10篇 |
2002年 | 19篇 |
2001年 | 16篇 |
2000年 | 16篇 |
1999年 | 12篇 |
1998年 | 86篇 |
1997年 | 48篇 |
1996年 | 39篇 |
1995年 | 24篇 |
1994年 | 27篇 |
1993年 | 25篇 |
1992年 | 8篇 |
1991年 | 9篇 |
1990年 | 12篇 |
1989年 | 13篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 7篇 |
1975年 | 3篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
排序方式: 共有747条查询结果,搜索用时 31 毫秒
71.
LE R?nnblom A Perers HS Vallin I Eriksson A Osterlind B Cederblad G Alm 《Canadian Metallurgical Quarterly》1997,105(7):531-536
A sensitive dissociation-enhanced lanthanide fluoroimmunoassay (DELFIA) was evaluated for ability to detect interferon-alpha (IFN-alpha) in serum of patients with acute infectious disease of less than one week's duration and a fever of > 38 degrees C. None of 36 patients with confirmed or probable bacterial disease was IFN-alpha positive. In contrast, 13/26 patients with viral infections had detectable levels of IFN-alpha in serum, all clearly positive (> or = 10 U/ml). The IFN-alpha positive serum samples were obtained early after onset of clinical disease, after a mean of 2.4 days. The IFN-alpha positive samples were obtained from 10 of the 12 patients with influenza or flu-like infection, and 3 of the 5 patients with varicella or herpes zoster. The IFN-alpha negative patients with viral disease (n = 9) included five patients with mononucleosis. The DELFIA should be useful in further studies of the value of IFN-alpha determinations in the identification of acute viral infections. 相似文献
72.
Kjell Eriksson 《International Journal of Fracture》2004,130(4):L201-L203
In a recent work Z.-H. Jin and C. T. Sun (2004) presented a derivation of the J-integral from the potential energy of a system, which is thought to circumvent previous cumbersome or flawed derivations. Two items in this work call for discussion; one is related to the effect of a singularity upon different types of contour integrals and the other to the strain energy difference term. 相似文献
73.
OBJECTIVE: To test a model for the study of inequalities in hospitalizations in the city of Ribeirao Preto (SP), understanding them to be due both to the social position of inpatients and also to health care policies in Brazil. MATERIAL AND METHOD: Using a hospital information system in existence for more than 25 years in the city of Ribeirao Preto-SP, 56.293 hospitalizations of municipal inhabitants occurring in some of the 12 general hospitals in 1993, were studied. Using the Brazilian occupancy classification for mortality, these inpatients were grouped on 6 occupational levels, as in the British classification: professional, intermediate, qualified non manual, qualified manual, partially qualified and unqualified. RESULTS AND CONCLUSIONS: Two-thirds of the inpatients had no place in the i.e. did not belong to the economically active population--and consisted of housewives, pensioners, children and students--and one third had some economic activity and thus belonged to the economically the active population. A close association was found between social strata and the classification of the hospital financing system into private, private group clinic and public health system patients. There were differences in hospital parameters as well as in morbidity patterns between these groups. The inequalities relating to average age, average age of hospital deaths, mean lengths of stay, hospital mortality, re-internment and frequency of diseases are discussed. This model allows the social position of the inpatient to be estimated using the hospital financing system, including also those patients with no economic activity, which covers the majority of the population. Social mechanisms created to compensate for inequalities in the welfare state do not cancel out the social differences. 相似文献
74.
H Pélicano C Pierra S Eriksson G Gosselin JL Imbach G Maury 《Canadian Metallurgical Quarterly》1997,40(24):3969-3973
The beta-L-enantiomers of 2',3'-dideoxyadenosine and 2',3'-didehydro-2',3'-dideoxyadenosine have been stereospecifically synthesized. In an attempt to explain the previously reported antiviral activities of these compounds, their enzymatic properties were studied with respect to adenosine kinase, deoxycytidine kinase, adenosine deaminase, and purine nucleoside phosphorylase. Adenosine deaminase was strictly enantioselective and favored beta-D-ddA and beta-D-d4A, whereas adenosine kinase and purine nucleoside phosphorylase had no apparent substrate properties for the D- or L-enantiomers of beta-ddA or beta-d4A. Human deoxycytidine kinase showed a remarkable inversion of the expected enantioselectivity, with beta-L-ddA and beta-L-d4A having better substrate efficiencies than their corresponding beta-D-enantiomers. Our results demonstrate the potential of beta-L-adenosine analogues as antiviral agents and suggest that deoxycytidine kinase has a strategic importance in their cellular activation. 相似文献
75.
76.
The aim of this consequential life cycle assessment (LCA) is to compare district heating based on waste incineration with combustion of biomass or natural gas. The study comprises two options for energy recovery (combined heat and power (CHP) or heat only), two alternatives for external, marginal electricity generation (fossil lean or intense), and two alternatives for the alternative waste management (landfill disposal or material recovery). A secondary objective was to test a combination of dynamic energy system modelling and LCA by combining the concept of complex marginal electricity production in a static, environmental systems analysis. Furthermore, we wanted to increase the methodological knowledge about how waste can be environmentally compared to other fuels in district-heat production. The results indicate that combustion of biofuel in a CHP is environmentally favourable and robust with respect to the avoided type of electricity and waste management. Waste incineration is often (but not always) the preferable choice when incineration substitutes landfill disposal of waste. It is however, never the best choice (and often the worst) when incineration substitutes recycling. A natural gas fired CHP is an alternative of interest if marginal electricity has a high fossil content. However, if the marginal electricity is mainly based on non-fossil sources, natural gas is in general worse than biofuels. 相似文献
77.
Hygiene-related and feed-related hoof diseases show different patterns of genetic correlations to clinical mastitis and female fertility 总被引:1,自引:0,他引:1
Buch LH Sørensen AC Lassen J Berg P Eriksson JÅ Jakobsen JH Sørensen MK 《Journal of dairy science》2011,94(3):1540-1551
Hoof diseases are a problem in many dairy herds. To study one aspect of the problem, genetic correlations between 4 hoof diseases, protein yield, clinical mastitis, number of inseminations, and days from calving to first insemination were estimated in first-parity Swedish Red cows using trivariate linear animal models. Occurrence of dermatitis, heel horn erosion, sole hemorrhage, and sole ulcer were reported by hoof trimmers. The data set contained about 314,000 animals with records on at least one of the traits; among these, about 64,000 animals had records on hoof diseases. Heritabilities were low for all hoof diseases (0.03 to 0.05). The hoof diseases fell into 2 groups: (1) dermatitis and heel horn erosion (i.e., diseases related to hygiene) and (2) sole hemorrhage and sole ulcer (i.e., diseases related to feeding). The genetic correlations between traits within the 2 groups were high (0.87 and 0.73, respectively), whereas the genetic correlations between traits in different groups were low (≤0.23). These results indicate that the 2 groups of hoof diseases are partly influenced by the same genes. All genetic correlations between hoof diseases and protein yield were low to moderate and unfavorable. Moderate and favorable genetic correlations were found between the feed-related hoof diseases and clinical mastitis (0.35 and 0.32), whereas the genetic correlations between the hygiene-related hoof diseases and clinical mastitis were low and not significantly different from zero. The genetic correlations between the hygiene-related hoof diseases and number of inseminations were low to moderate and favorable (0.32 and 0.22), and the genetic correlations between the feed-related hoof diseases and number of inseminations were low and not significantly different from zero. A moderate genetic correlation was found between sole ulcer and days from calving to first insemination (0.33), whereas the genetic correlations between days from calving to first insemination and sole hemorrhage and the hygiene-related hoof diseases were low and not significantly different from zero. In general, the 2 groups of hoof diseases showed different patterns of genetic correlations to the other functional traits, but both were unfavorably correlated to protein yield. A simulation study showed that inclusion of hoof diseases in the selection index will not only reduce the genetic decline in resistance to hoof diseases but also be favorable for other functional traits and improve overall genetic merit. 相似文献
78.
Eriksson A Bergquist J Edwards K Hagfeldt A Malmström D Hernández VA 《Analytical chemistry》2011,83(3):761-766
A simple method for on-target enrichment and subsequent separation and analysis of phosphorylated peptides is presented. The tryptic digest of a phosphorylated protein, in this case β-casein, is loaded onto a spot on a thin stripe made of mesoporous TiO(2) sintered onto a conductive glass surface. After washing with a salicylic buffer in order to remove the nonphosphorylated peptides, the stripe is placed in an elution chamber containing a phosphate solution. In a way analogous to thin layer chromatography (TLC), the phosphate solution acts as an eluent, clearly separating multi- and monophosphorylated peptides. By performing matrix-assisted laser desorption-ionization mass spectrometry (MALDI-MS) along the stripe, the detection of all phosphorylated peptides present in the digest is facilitated, as they are isolated from each other. The method was also tested on commercial drinking milk, achieving successful separation between multi- and monophosphorylated peptides, as well as a detection limit in the femtomole range. As the enrichment, separation, and analysis take place in the same substrate, sample handling and risk of contamination and sample loss is minimized. The results obtained suggest that the method, once optimized, may successfully provide a complete phosphoproteome. 相似文献
79.
J Kartus S Stener R Nilsén U Nilsson BI Eriksson J Karlsson 《Canadian Metallurgical Quarterly》1998,8(6):449-455
Dairy calves under 14 days of age with naturally occurring, uncomplicated diarrhea were treated for 3 days with a hypertonic oral electrolyte solution with (n = 15) or without (n = 12) psyllium. Clinical response and clinical pathology data were compared between the 2 groups. Glucose absorption was evaluated on days 1 and 3 by measurement of plasma glucose and lactate and serum insulin concentrations for 4 hours after formula administration. On day 1, glucose, lactate, and insulin concentrations were lower in psyllium-fed calves than in control calves, with significant differences noted in glucose and lactate concentrations at several time points (P < 0.05). Plasma lactate concentrations were higher at several times in both treatment groups on day 3 than on day 1 (P < 0.05). Fecal consistency was markedly different in psyllium-fed calves as compared with control calves within 24 hours of psyllium supplementation. Fecal percent dry matter content was lower in psyllium-fed calves than in control calves at least once a day during supplementation and on day 3 compared with day 0 in the psyllium-fed calves (P < 0.05). There were no significant differences in clinical performance scores, hydration status, arterial blood gas, serum anion gap, electrolyte, or total CO2 concentrations. Addition of psyllium to an oral electrolyte solution resulted in immediate alterations in glucose absorption without impairing rehydration in diarrheic calves, but differences were transient and did not affect clinical outcome. 相似文献
80.
EN Bazhenova YI Deryabina O Eriksson RA Zvyagilskaya NE Saris 《Canadian Metallurgical Quarterly》1998,273(8):4372-4377
The Ca2+ transport system of Endomyces magnusii mitochondria has been shown previously to be activated by spermine. Here we report it to be regulated also by low, physiological ADP concentrations, by the intramitochondrial NADH/NAD+ ratio, and by Ca2+ ions. The combination of all these physiological modulators induced high initial rates of Ca2+ uptake and high Ca2+-buffering capacity of yeast mitochondria, enabling them to lower the medium [Ca2+] to approximately 0.2 microM. The mechanisms of stimulation by these agents are discussed. 相似文献