全文获取类型
收费全文 | 4962篇 |
免费 | 4篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 71篇 |
金属工艺 | 2篇 |
建筑科学 | 1篇 |
矿业工程 | 2篇 |
能源动力 | 3篇 |
轻工业 | 7篇 |
石油天然气 | 3篇 |
无线电 | 19篇 |
一般工业技术 | 14篇 |
冶金工业 | 4831篇 |
自动化技术 | 11篇 |
出版年
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 7篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 4篇 |
2014年 | 1篇 |
2013年 | 3篇 |
2012年 | 1篇 |
2011年 | 8篇 |
2010年 | 8篇 |
2009年 | 5篇 |
2008年 | 7篇 |
2007年 | 3篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 18篇 |
2002年 | 3篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 151篇 |
1998年 | 1463篇 |
1997年 | 871篇 |
1996年 | 542篇 |
1995年 | 302篇 |
1994年 | 271篇 |
1993年 | 295篇 |
1992年 | 31篇 |
1991年 | 63篇 |
1990年 | 58篇 |
1989年 | 64篇 |
1988年 | 62篇 |
1987年 | 53篇 |
1986年 | 63篇 |
1985年 | 48篇 |
1984年 | 1篇 |
1983年 | 10篇 |
1982年 | 22篇 |
1981年 | 28篇 |
1980年 | 26篇 |
1979年 | 3篇 |
1978年 | 13篇 |
1977年 | 128篇 |
1976年 | 286篇 |
1975年 | 9篇 |
1962年 | 1篇 |
1955年 | 5篇 |
1924年 | 2篇 |
1920年 | 1篇 |
排序方式: 共有4966条查询结果,搜索用时 15 毫秒
21.
JJ Ellestad-Sayed RA Nelson MA Adson WM Palmer EH Soule 《Canadian Metallurgical Quarterly》1976,29(12):1333-1338
To investigate further an apparent relationship between chronic ulcerative and granulomatous colitis and pantothenic acid deficiency, colonic tissues obtained at the time of colectomy in 29 patients with these disorders were assayed for pantothenic acid and for coenzyme A (CoA) activity. For comparison, normal colonic tissues free of pathological lesions were obtained from 31 patients having colectomy for carcinoma or diverticulitis. Plasma, red blood cells, and colonic mucosa were assayed microbiologically for free and total pantothenic acid. The activity of CoA in colonic mucosa was determined by assaying the acetylation of sulfanilamide. Concentrations of free, bound, and total pantothenic acid in blood and in colonic mucosa did not differ between the two groups of patients. Bound pantothenic acid increased linearly with total pantothenic acid. Colonic mucosa concentrated free pantothenic acid to about 50 times the level of blood, and pantothenic acid in red cells was similar to the concentration in plasma. Compared to normal gut mucosa, CoA activity was markedly low in mucosa from patients with chronic ulcerative or granulomatous disease despite the presence of normal amounts of free and bound pantothenic acid. A block in the conversion of bound pantothenic acid to CoA in diseased mucosa is suggested. 相似文献
22.
JA De Lange WP Rutten NA Schmidt JG Eernisse JJ Veltkamp 《Canadian Metallurgical Quarterly》1976,14(10):485-497
In the routine laboratory for hematology conflicting results may be obtained for the red blood cell parameters with the Coulter Counter Model S. These parameters2) are: mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC). When the values of the MCHC are above 36 g/dl something must be wrong with the blood sample of the patient. One of the reasons can be agglutination e.g. by cold agglutinins. The blood sample should be reanalysed before and after heating for 1 hour at 37 degrees C. If the values change: cold agglutinins are present; if no change occurs paraproteins, or other disturbing factors, such as bilirubin or high leucocyte levels, will be found. MCH values may also be high in some cases e.g. if the red blood cells are coated with antibodies (Coombs test positive) or after ingestion of medicines like Azathioprine. These examples show that it is possible in some cases to correlate immunological findings with the red blood cell parameters. In addition to the results with the Coulter Counter Model S, some observations on the Hemalog (Technicon) are also presented. 相似文献
23.
A second examination at the expense of the party adjudged to be in error is based on Section 13 of the Meat Inspection Act in the Netherlands, which has been elaborated in Sections 51 and 51a of the Meat Inspection Order. The procedure to be adopted by the second veterinary-surgeon inspector, however, has not been stipulated. The need for clear instructions is stressed. The present paper was designed to promote objectivity and uniformity in second inspections to provide legal security for the owner of the slaughtered animal as well as for the first veterinary-surgeon inspector. 相似文献
24.
C Bartholomew KF McGeeney JJ Murphy O Fitzgerald H Sankaran 《Canadian Metallurgical Quarterly》1976,63(10):807-810
This study examined the action of the venom of the scorpion Tityus trintatis on the pancreas and gastrointestinal tract in anaesthetized dogs, on the isolated extracorporeal haemoperfused canine pancreas and on the isolated canine sphincter of Oddi. The venom induces exocrine secretion in both the isolated and intact pancreas and causes contraction of the isolated sphincter of Oddi. These results are discussed in relation to the pathogenesis of acute scorpion pancreatitis and possibly of some other forms of acute pancreatitis. 相似文献
25.
We describe a female infant with the cervical vertebral fusion (Klippel-Feil) syndrome whom we recognized at birth because of her short neck, restriction of cervical movement, and low posterior hairline. X-ray examination showed anomalies of C1, and between C2-3 and C3-4; thus, we classified her as type II, with variable cervical fusion. At 24 months she was small and manifested hearing deficiency. The mother and father were consanguineous with five common ancestors four generations ago, which resulted in a coefficient of inbreeding equivalent to a second cousin relationship. The parents and grandparents were phenotypically normal, and the parents were radiologically normal. This form of the syndrome has previously been said to be autosomal dominant. Our conclusion of determination by a single autosomal recessive gene is evidence of genetic heterogeneity. 相似文献
26.
Plasma unconjugated estrone (E1), estradiol-17beta (E2) and estriol (E3), and HCS were measured in the same plasma samples collected throughout pregnancy in 19 gestational diabetics (GD) and 21 diabetics (D). When compared to the results obtained in 22 normal subjects, plasma levels of E1 and E2 were significantly elevated in D in the second half of gestation. The results were intermediate although closer to the normals, in GD. E3 values were not different from the normals in both D and GD. HCS values were lower than normal in early pregnancy in both D and GD. In late pregnancy HCS levels were not different from normal in either D or GD, although some individual values were much above the upper limit in some diabetic patients. The hormonal ratios in D and GD parallel those in normals, although E3/E2 and HCS/E2 were lower in D. These results are discussed with respect to the different behaviour of E2 and E3, taking into account the difference in their respective biosynthetic pathways. Besides a possible quantitative modification of the placental function in D, the results could tentatively be explained by a qualitative change in the fetal estrogen precursors to placental aromatization, in favour of the 16 non-hydroxylated compound. However, maternal modifications in precursor production or in estrogen metabolism can be an alternative hypothesis. Finally, the present work does not support the hypothetical estrogen deficiency in diabetic pregnancy. Estrogen treatment appears to have no objective justification. 相似文献
27.
AJ Haller M Katlic DW Shermeta IJ Shaker JJ White 《Canadian Metallurgical Quarterly》1976,184(5):554-557
Volatile free fatty acids (VFA) in blood increased approximately twofold in dogs subjected to total hepatectomy. The average total plasma VFA preoperatively was 1,585 mug percent and shortly before death, postoperatively, was 2,798 mug percent. The corresponding red cell concentrations were essentially the same. Acetic acid was 81 percent of the total VFA, propionic acid 7 percent, isobutyric acid 4 percent, butyric acid one percent, and isovaleric acid 5 percent. There was little or no isovalerate in red cells. The increments in the individual fatty acids after hepatectomy were highly variable, but the average increase with time was almost linear. The increase in VFA probably reflects an increased utilization of the branched-chain aminoacids by extrahepatic tissues. 相似文献
28.
29.
A selective agar medium (pork plasma medium for S. aureus (PPSA)) enables the direct enumeration of coagulase-positive staphylococci. This medium is based on the Baird-Parker agar without egg yolk and is supplemented with pig plasma. Colonies of Staphylococcus aureus are surrounded by a halo of precipitated fibrin. When foods such as dairy products contain large numbers of egg yolk-negative strains of S. aureus, the PPSA agar has the advantage over egg yolk containing media such as Baird-Parker agar that fewer suspect colonies have to be confirmed. 相似文献
30.