全文获取类型
收费全文 | 3095篇 |
免费 | 0篇 |
专业分类
综合类 | 1篇 |
化学工业 | 9篇 |
建筑科学 | 1篇 |
轻工业 | 37篇 |
一般工业技术 | 5篇 |
冶金工业 | 3036篇 |
自动化技术 | 6篇 |
出版年
2016年 | 3篇 |
2013年 | 1篇 |
2012年 | 2篇 |
2010年 | 5篇 |
2007年 | 2篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2003年 | 7篇 |
2002年 | 2篇 |
2001年 | 1篇 |
1999年 | 105篇 |
1998年 | 947篇 |
1997年 | 552篇 |
1996年 | 333篇 |
1995年 | 199篇 |
1994年 | 157篇 |
1993年 | 174篇 |
1992年 | 17篇 |
1991年 | 46篇 |
1990年 | 36篇 |
1989年 | 46篇 |
1988年 | 58篇 |
1987年 | 48篇 |
1986年 | 32篇 |
1985年 | 21篇 |
1983年 | 7篇 |
1982年 | 14篇 |
1981年 | 14篇 |
1980年 | 29篇 |
1979年 | 2篇 |
1978年 | 11篇 |
1977年 | 66篇 |
1976年 | 152篇 |
1975年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有3095条查询结果,搜索用时 15 毫秒
41.
Young growing pigs of both sexes were subjected to changes in (1) energy intake, (2) ambient temperature, and (3) bulk of food. The rate of disappearance of injected 125I-labelled thyroxine from the plasma (K) was measured. An analysis of variance revealed that the effect attributable to changes in the energy content of the food intake was statistically significant (P less 0-01). A change in ambient temperature had no statistically significant effect on K, nor did a change in the bulk of food when energy intake was constant (P less than 0-05). 相似文献
42.
In pregnant female rat, oxygen tension was measured in vivo with an oxygen microelectrode and the following statistically significant data (Student's test) were obtained: -- not significant variability in four groups of six control rats; -- highly significant decrease of oxygen tension twenty-four hours after biovariectomy in four groups of six operated rats; -- in twelve operated and treated by substitutive hormonotherapy rats, pO2 was at the same level than in control rats; -- in eighteen operated rats, the oxygen tension measured after embryonic death was identical to control rats. These experiments clearly demonstrate twenty four hours after biovariectomy a decreased oxygen tension. Simultaneously to this decrease, a diminution of uterine blood flow takes place. This pO2 diminution should be dependent on decrease of ovarian hormones since the substitutive hormonotherapy prevents its appearance. A good explanation of this phenomenon is the high requirement of hypoxic embryo for oxygen; moreover after the embryonic death, the intra-uterine pO2 increases. 相似文献
43.
44.
45.
46.
An innovative model for organising social services in a community, the Imbrication Model, is contrasted with two traditional models, the Entrepreneurial and the Umbrella Agency. The structural characteristics and dynamics of the three models are illustrated with actual case histories. Imbrication Model calls for the interlocking of personnel from several agencies, with the purpose of redirecting the dysfunctional interagency rivalry prevalent in the traditional models. Imbrications at all organisational levels--Board of Directors, Administrators and Staff--facilitate adoption of the superordinate goal of providing clients with the best services available, regardless of which particular agency delivers the service. Few observers of the current social service scene would challenge the statement that needs for service are unlimited and resources limited. In the USA the imbalance between needs and resources persists despite a decade of massive governmental programmes intended to alleviate social ills. Recent substantial cutbacks in federal funds, moreover are not likely to improve the situation. The resource shortage involves more than a limitation of funds. Deliverers of service and competent programme administrators are also on critically short supply. These shortages are more often than not exacerbated by a chronic spirit of competition among agencies and programmes at the local level. Three organizational models for the delivery and administration of social services, two conventional and one of more recent date, are examined in this article. The innovative model, which has been named the Imbrication Model, explicitly calls for redirecting interagency rivalry and competition. Its ambitious goal is to integrate the efforts of those attempting to meet a community's social service needs. 相似文献
47.
48.
49.
DF Birt PM Pour DL Nagel T Barnett D Blackwood E Duysen 《Canadian Metallurgical Quarterly》1997,18(11):2107-2111
Dietary energy restriction was previously shown to be effective in preventing a wide range of experimentally induced cancers. Studies were conducted to assess the influence on pancreatic carcinogenesis of dietary energy restrictions (reduced fat and carbohydrate) of 10%, 20% or 40% in comparison with control in Syrian hamsters treated with N-nitrosobis(2-oxopropyl)amine (BOP). Two carcinogenesis studies were conducted. One used a single treatment with 20 mg BOP/kg body weight and followed hamsters for 102 weeks following treatment, and the other used three weekly treatments of 20 mg BOP/kg body weight and followed hamsters for 45 weeks after treatment. Hamsters were fed control or energy restricted diet beginning the week following the last BOP treatment. Pancreatic carcinomas were induced in 9-18% of the hamsters in the first experiment and in 59-66% of the animals in the second. Dietary energy restriction did not influence carcinoma incidence in either study, and in the second experiment the multiplicity of tumors was higher in the 40% energy restriction (ER) group than in control hamsters. Plasma corticosterone was suppressed by BOP treatment, particularly in the 20% and 40% ER hamsters in the second experiment, and diet or BOP treatment did not significantly alter plasma cortisol. Pancreatic protein kinase Czeta measured by Western blot was highest in the cytosol and particulate fractions of the 40% ER hamsters in the first experiment. These results indicate that dietary energy restriction is not effective in the prevention of BOP induced pancreatic carcinogenesis in the Syrian hamster. 相似文献
50.
Venous thromboembolism is a leading cause of death and morbidity after extended surgery for early malignancies of the cervix and uterus. Two hundred eighty-one patients who underwent such surgery were retrospectively evaluated for associated risk factors, the incidence of clinically significant thromboembolic complications, and prophylactic value of low-dose heparin and antiembolism stockings. Significant thromboemboli were encountered in 7.8% of patients postoperatively and accounted for the only 4 postoperative deaths. Forty-five percent of patients who developed thromboemboli did so after discharge from the hospital. The preoperative risk factors found to be associated with thromboembolism, in order of statistical significance, were weight in excess of 85.5 kg, advanced clinical stage of malignancy, and radiation therapy within 6 weeks of the operative procedure. Low-dose heparin therapy and the use of antiembolism stockings as preventative measures did not appear to reduce the incidence of thromboembolic complications. A prospective study will be necessary to evaluate definitely the effectiveness of various therapeutic modalities on thromboembolism in gynecologic oncology patients. 相似文献