全文获取类型
收费全文 | 769篇 |
免费 | 7篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 30篇 |
金属工艺 | 2篇 |
机械仪表 | 3篇 |
建筑科学 | 19篇 |
矿业工程 | 1篇 |
能源动力 | 2篇 |
轻工业 | 10篇 |
水利工程 | 11篇 |
无线电 | 33篇 |
一般工业技术 | 47篇 |
冶金工业 | 598篇 |
原子能技术 | 3篇 |
自动化技术 | 16篇 |
出版年
2020年 | 2篇 |
2019年 | 2篇 |
2017年 | 5篇 |
2016年 | 2篇 |
2015年 | 5篇 |
2013年 | 11篇 |
2012年 | 4篇 |
2011年 | 13篇 |
2010年 | 4篇 |
2009年 | 4篇 |
2008年 | 5篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 8篇 |
2004年 | 5篇 |
2003年 | 8篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 11篇 |
1998年 | 169篇 |
1997年 | 108篇 |
1996年 | 65篇 |
1995年 | 40篇 |
1994年 | 25篇 |
1993年 | 29篇 |
1992年 | 13篇 |
1991年 | 8篇 |
1990年 | 3篇 |
1989年 | 7篇 |
1988年 | 10篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 10篇 |
1980年 | 16篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 30篇 |
1976年 | 74篇 |
1975年 | 3篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1966年 | 2篇 |
1962年 | 2篇 |
1954年 | 1篇 |
排序方式: 共有777条查询结果,搜索用时 15 毫秒
1.
NW Tomkins NN Jonsson MP Young AN Gordon KA McColl 《Canadian Metallurgical Quarterly》1997,75(10):722-723
On the basis of clinical signs and histological findings eight 9-month-old male rusa deer (Cervus timorensis) were diagnosed with sheep associated-malignant catarrhal fever. Following a variable course involving rectal temperatures around 40.5 degrees C, depression, inappetence, diarrhoea, corneal opacity and hypopyon all animals died or were euthanased over a 5-week period. Severe multifocal vasculitis, mainly periglomerular and in the arcuate vessels were consistent histological findings which in the past have been adequate to confirm clinical diagnosis of sheep associated-malignant catarrhal fever. A nested polymerase chain reaction test has been used to detect a sheep associated-malignant catarrhal fever PRC product, 238 base-pairs in size, in DNA extracted from lymphocyte preparations. The result supported the diagnosis of sheep associated-malignant catarrhal fever in these deer. 相似文献
2.
The throughput performance of a broadcast DS/SSMA packet radio network using adaptive error control is investigated. Simulated results for the network throughput against offered load are presented and show that adaptive error control significantly increases the throughput performance at all offered loads 相似文献
3.
NV Zheleznova SL Mukomolov AB Zhebrun FS Noskov II Malkova EP Shargorodskaia AD Al'tshte?n VA Pliutnikova IN Lavrent'eva NN Ptichnikova 《Canadian Metallurgical Quarterly》1996,(5):49-53
The use of a recombinant poxvirus (RPV) strain, expressing HBsAg in the process of reproduction in different bioreactor systems under stationary and bioreactor conditions of cultivation, made it possible to obtain highly purified HBsAg. The identity and purity of HBsAg was confirmed by the analysis of its amino acid composition, SDS electrophoresis in polyacrylamide gel, electron microscopy and high-performance liquid chromatography. Good prospects of the use of RPV-expressed gene engineering HBsAg as the basis vaccines against hepatitis B was demonstrated in 10 experimental batches of vaccine. All batches of the preparation had pronounced immunogenicity and were safe and nontoxic in animal experiments. The ID50 of experimental batches did not exceed 211 ng/ml, which, according to the data of comparative experiments, was lower than, or equal to, corresponding values of analogous foreign commercial preparations, based on plasma or yeast HBsAg. 相似文献
4.
NN McGihon 《Canadian Metallurgical Quarterly》1996,34(6):31-35
1. Most psychiatric and mental health professionals are experienced with writing in some form as a tool for encouraging patients to express feelings and identify stressors. 2. Narrative writing, or journal writing, can also help patients identify areas of conflict in their lives and to clarify complicated issues. 3. Writing can be used effectively with patients who are reluctant or embarrassed to speak openly in one-on-one interactions. 相似文献
5.
Summary We consider a circular cylindrical membrane subjected to longitudinal extension and twist. The associated equilibrium deformation is considered to be axisymmetric and the analysis is based on a direct two-dimensional formulation. Wrinkling of the membrane is taken into account in an approximate way by introducing arelaxed strain energy function derived from the neo-Hookean strain energy for isotropic elastic solids. Analytical formulae for wrinkled parts of the membrane are used to corroborate the results of a numerical treatment of the full boundary value problem.Dedicated to the memory of A. C. Pipkin 相似文献
6.
The ultrastructural diagnosis of tumors requires a careful analysis that should be done in an orderly fashion. It requires precise planning from the time of specimen collection to the selection of the area to be examined. Pictures must be taken systematically and every micrograph should allow to answer whether the number of cells photographed is adequate; whether mitoses are present, what is the pattern of the tumor; what is the appearance of the cell membrane; whether the cells are joined by junctional complexes; whether free surfaces possess microvilli or cilia; what organelles are present and how they are distributed; whether there are secretory granules, melanosomes, or other cytoplasmic elements. Nuclear and nucleolar size and shape have to be taken into consideration. The composition of the interstitial extracellular matrix is important in certain types of tumors. Although these questions are not the only ones to be addressed, their use in a logical fashion is helpful when it concerns the ultrastructural diagnosis. 相似文献
7.
8.
OBJECTIVES: Injury is the leading cause of death in the male working population of Brazil. An important fraction of these deaths are work related. Very few cohort studies of steel workers, and none from developing countries, have reported on mortality from injuries. This paper analyses mortality from work and non-work related injuries among Brazilian steel workers. METHODS: Deaths during employment from 1 January 1977 to 30 November 1992 were analysed in a cohort of 21,816 male steel workers. Mortality rates specific for age and calendar year among the workers were compared with those of the male population of the state where the plant is located. Work related injuries were analysed by comparing the mortality rates for different subgroups of the cohort. RESULTS: The number of deaths (391) was less than half that expected based on death rates of the general population. Over 60% (242) of deaths were due to injuries. Mortality from most causes was substantially below that in the general population, but that from unintentional injury, was 50% above that of the general population. Standardised mortality ratios (SMRs) were highest for the youngest and the oldest employees and for labourers and clerical workers. Mortality from motor vehicle injury was twice that expected from population rates (SMR = 209, 95% confidence interval (95% CI) 176-244). There was a 67% fall in the age adjusted mortality from occupational injuries in the study period. CONCLUSION: The healthy worker effect in this cohort was greater than that commonly found in studies of occupational groups in developed countries, probably because of a greater socioeconomic gap between employed and unemployed populations in Brazil, and unequal distribution of health care resources. Mortality was especially high for motor vehicle injuries. The fall in mortality from occupational injuries during the study period was probably due to improvement in safety standards, increased automation, and better medical care. There is a need to investigate risk factors for unintentional injuries among steel workers, especially those due to motor vehicle injuries. Prevention of occupational and nonoccupational injuries should be a main priority in Brazil. 相似文献
9.
IA Bukaeva NT Ra?khlin NA Probatova EA Smirnova NN Tupitsyn EN Sholokhova R Gossrau 《Canadian Metallurgical Quarterly》1997,59(4):31-38
26 cases of lymphoproliferative diseases were studied: 8 cases of reactive follicular hyperplasia (RFH), 11 cases of non-Hodgkin's malignant lymphomas (NML), 7 cases of lymphogranulomatosis (LGM). Only gamma-glutamyl transpeptidase (GGT) was found in lymphoid cells of B- and T-dependent areas of lymph nodes with reactive changes as well as in tumor cells of NML and LGM. GGT activity was more pronounced in NML of high-grade malignancy (centroblast and immunoblast) as compared to lymphomas of lower grade of malignancy (lymphocytic, centroblast-centrocytic and in Lennert lymphoma). GGT activity in cells of Hodgkin and Berezovsky-Sterberg in some cases of LGM was high, in others low. Significant differences in GGT activity between RFH and follicular centroblast-centrocytic lymphoma were not found. Activity of aminopeptidase M was observed in histiocytes, fibroblasts, vessels and areas of connective tissue growth. Aminopeptidase A activity was observed in vessels only. Activity of dipeptidyl(amino)peptidase IV was observed in some lymphoid cells in RFH, NML and LGM. Thus, GGT activity may be considered as a differential-diagnostic marker in separating NML of high and low degree of malignancy and this may presume a different sensitivity to the therapy. 相似文献
10.