全文获取类型
收费全文 | 2932篇 |
免费 | 9篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 34篇 |
金属工艺 | 1篇 |
机械仪表 | 1篇 |
矿业工程 | 1篇 |
能源动力 | 5篇 |
轻工业 | 21篇 |
无线电 | 14篇 |
一般工业技术 | 11篇 |
冶金工业 | 2831篇 |
原子能技术 | 6篇 |
自动化技术 | 15篇 |
出版年
2021年 | 2篇 |
2020年 | 3篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2014年 | 5篇 |
2013年 | 4篇 |
2012年 | 4篇 |
2011年 | 3篇 |
2010年 | 4篇 |
2009年 | 4篇 |
2008年 | 6篇 |
2007年 | 2篇 |
2006年 | 4篇 |
2005年 | 7篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2002年 | 3篇 |
2000年 | 3篇 |
1999年 | 84篇 |
1998年 | 917篇 |
1997年 | 490篇 |
1996年 | 342篇 |
1995年 | 188篇 |
1994年 | 146篇 |
1993年 | 149篇 |
1992年 | 20篇 |
1991年 | 46篇 |
1990年 | 34篇 |
1989年 | 41篇 |
1988年 | 35篇 |
1987年 | 49篇 |
1986年 | 38篇 |
1985年 | 25篇 |
1983年 | 3篇 |
1982年 | 10篇 |
1981年 | 17篇 |
1980年 | 20篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 57篇 |
1976年 | 135篇 |
1975年 | 6篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1969年 | 3篇 |
1968年 | 2篇 |
1967年 | 3篇 |
1966年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有2941条查询结果,搜索用时 15 毫秒
941.
Diseases of yearling feedlot cattle in Colorado 总被引:6,自引:0,他引:6
R Jensen RE Pierson PM Braddy DA Saari LH Lauerman JJ England DP Horton AE McChesney 《Canadian Metallurgical Quarterly》1976,169(5):497-499
During all of 1974 we surveyed, for illnesses and deaths, about 407,000 yearling feedlot cattle. The morbidity was 5.1%, with a case mortality of 18.9% and a population mortality of 1.0%. Both morbidity and mortality were higher during fall and winter than during spring and summer. Of the 3,943 dead cattle, 1,988 were necropsied. The most prevalent diseases were: pneumonia, 48%; diphtheria, 6%; brisket disease, 6%; hemorrhagic colitis, 5%; riding injury, 4%; bloat, 3%; calculosis, 2%; endocarditis, 2%; abomasal ulcers, 2%; bovine viral diarrhea, 2%; embolic pulmonary aneurysm, 1%; and pulmonary edema, 1%. 相似文献
942.
Eighty-six consecutive patients operated on for atherosclerotic occlusion of the aortoiliac segment were examined regarding the severity of the disease in the left or right iliac arteries. Sixty-nine percent of 78 patients were found to have predominantly more severe lesions on the left side. A study of the geometric anatomy of the aortoiliac region in 14 male and 12 female cadavers revealed that the right common iliac take-off angle was wider than the left and the radius of curvature of the right osculating circle at the aortoiliac bifurcation was smaller than the left, with the asymmetry of the region being much more marked in males than in females. The predilection of occlusive disease for the left iliac artery is explained on the basis of these differences in local geometric anatomy and their effect on the local hemodynamics. 相似文献
943.
944.
The responses of rabbit aortic strips superfused with noradrenaline, adrenaline and 5-HT were studied alone and in combination with ketamine (50 mug/ml). Ketamine caused a slight depression of the isolated aorta but potentiated responses to adrenaline but not to noradrenaline or 5-hydroxytryptamine. Ketamine did not potentiate aortic strips contracted to a stable level by pyrogallol and adrenaline. Experiments carried out with COMT from homogenates of rat liver showed that, in contrast to pyrogallol (10(-5) M), ketamine (10(-3) M) did not inhibit the enzyme. Other experiments with rabbits given 6-hydroxydopamine showed that aortas of these rabbits responded in a similar manner to controls when treated with ketamine and catecholamines. Results obtained with aortas contracted by adrenaline and noradrenaline with ketamine present, followed by oil immersion, showed that ketamine prolonged greatly the relaxation induced by adrenaline and to a lesser extent the relaxation induced by noradrenaline. The results of these studies indicate that ketamine prevented catecholamines from reaching the intracellular site of COMT. In this respect, ketamine can be termed an inhibitor of uptake site 2. If this hypothesis is valid then the action of ketamine on vascular tissue might explain the cardiovascular effects of the drug in man and experimental animals. 相似文献
945.
A case of complicated spontaneous esophageal perforation is presented. The control of gastroesophageal reflux by esophageal banding appears to be a crucial factor in healing. Using a modified esophageal exclusion technique without sacrifice of the esophagus proves to be both effective and lifesaving. 相似文献
946.
JM Mishler AW Janes B Lowes C Farfan PM Emerson 《Canadian Metallurgical Quarterly》1976,34(3):387-394
The minimal inhibitory concentrations of 32 antimicrobial agents were established for 73 strains of Propionibacterium acnes and four related species (P. granulosum, P. avidum, Corynebacterium minutissimum, and C. parvum). Most strains showed good susceptibility to those agents usually considered active against gram-positive organisms. With the exception of C. minutissimum, the strains tested revealed more or less identical susceptibility ranges. The lowest minimal inhibitory concentrations were observed with benzylpenicillin, ampicillin, cephalothin, rifampin, erythromycin, clindamycin, and minocycline. C. minutissimum was more susceptible to gentamicin, sisomicin, tobramycin, and fusidic acid but more resistant to most other drugs than were the other species examined. 相似文献
947.
Highly conformal dose distributions can be generated by intensity-modulated radiotherapy. Intensity-modulated beams (IMBs) are generally determined by inverse-planning techniques designed to maximize conformality. Usually such techniques apply no constraints on the form of the IMBs which may then develop fine-scale modulation. In this paper we present a technique for generating smoother IMBs, which yields a dose distribution almost identical to that without the constraint on the form of the IMBs. The method applies various filters successively at intervals throughout the iterative inverse planning. It is shown that the IMBs so determined using a simple median window filter have desirable properties in terms of increasing the efficiency of delivery by the dynamic multileaf collimator method and may be 'more like conventional beams' than unconstrained, highly modulated IMBs. 相似文献
948.
949.
950.
CH Hélénon C Michel P Jacri PM Haddad R Vannier CH Gallouedec H Brocard 《Canadian Metallurgical Quarterly》1976,57(6-7):477-486
The authors present the results of selective bronchial and parietal arteriography of pulmonary systemic hypervascularization, in 83 cases. They emphasize the advantages of previous pulmonary venous angiography and overall aortography for the success of selective injections. Failures are evaluated at 6 to 7%. On occasions, a medullary branch was opacified. No medullary accidents were noted. The angiographic appearances of the lesions encountered are described. A comparative study of the angiographic results of non-tumoral acquired lesions was carried out in those patients with hemoptysis and in those who were free from them. 相似文献