全文获取类型
收费全文 | 742153篇 |
免费 | 9655篇 |
国内免费 | 2004篇 |
专业分类
电工技术 | 13866篇 |
综合类 | 1034篇 |
化学工业 | 111754篇 |
金属工艺 | 27083篇 |
机械仪表 | 21115篇 |
建筑科学 | 18428篇 |
矿业工程 | 2943篇 |
能源动力 | 20351篇 |
轻工业 | 67078篇 |
水利工程 | 6916篇 |
石油天然气 | 11572篇 |
武器工业 | 44篇 |
无线电 | 87181篇 |
一般工业技术 | 141446篇 |
冶金工业 | 145369篇 |
原子能技术 | 14032篇 |
自动化技术 | 63600篇 |
出版年
2021年 | 6343篇 |
2020年 | 4632篇 |
2019年 | 5935篇 |
2018年 | 10067篇 |
2017年 | 9787篇 |
2016年 | 10278篇 |
2015年 | 7214篇 |
2014年 | 12031篇 |
2013年 | 34133篇 |
2012年 | 19083篇 |
2011年 | 26624篇 |
2010年 | 20907篇 |
2009年 | 23669篇 |
2008年 | 24339篇 |
2007年 | 24030篇 |
2006年 | 21127篇 |
2005年 | 19437篇 |
2004年 | 18751篇 |
2003年 | 18424篇 |
2002年 | 17604篇 |
2001年 | 17742篇 |
2000年 | 16641篇 |
1999年 | 17681篇 |
1998年 | 44970篇 |
1997年 | 31747篇 |
1996年 | 24524篇 |
1995年 | 18548篇 |
1994年 | 16459篇 |
1993年 | 16013篇 |
1992年 | 11670篇 |
1991年 | 10979篇 |
1990年 | 10791篇 |
1989年 | 10486篇 |
1988年 | 9940篇 |
1987年 | 8659篇 |
1986年 | 8647篇 |
1985年 | 9872篇 |
1984年 | 9089篇 |
1983年 | 8248篇 |
1982年 | 7666篇 |
1981年 | 7853篇 |
1980年 | 7392篇 |
1979年 | 7240篇 |
1978年 | 6843篇 |
1977年 | 8349篇 |
1976年 | 10897篇 |
1975年 | 5988篇 |
1974年 | 5707篇 |
1973年 | 5791篇 |
1972年 | 4768篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
991.
Spirituality is a critical component of the holistic mind-body-spirit model embraced by Hospice. Hospice chaplains, as part of the caregiving team, must understand their abilities and limitations in providing spiritual guidance to others who may differ in religious and spiritual beliefs. 相似文献
992.
J Weber P Majer J Litera J Urban M Soucek J Vondrásek J Konvalinka P Novek J Sedlácek P Strop HG Kr?usslich I Pichová 《Canadian Metallurgical Quarterly》1997,341(1):62-69
The results of investigation of haptoglobin (Hp) types in 596 donor blood samples in some towns of Ukraine (Dnepropetrovsk, Kharkov, Odessa, Kiev, Uzhgorod, Zhitomir) are presented. Three normal Hp types (Hp1-1, Hp2-1 and Hp2-2) have been found. The reliable interpopulation differences in the Hp types frequency were not found. On the whole the Hp types frequency in the type Hp1-1 comprised 12.7%. In the type Hp2-1-48.1% and in the type Hp2-2-36.5%. The frequency of the gene Hp1 is 0.38. The frequency of the Hp types and of the gene Hpl in Ukraine is similar to that in population of Eastern Europe and European Part of Russia. 相似文献
993.
M Leach 《Canadian Metallurgical Quarterly》1997,93(22):52-55
We are continually expanding our knowledge of JCA and establishing our understanding on an ever-increasing knowledge base encompassing immunology, immunogenetics, physiology, psychology and sociology. The causes and treatment of this condition are multifactoral and no one discipline can hope to embrace all of them. Nurses, particularly those with rheumatological and/or paediatric expertise, are uniquely placed to provide the link between patient, the family and health care team and thus to coordinate treatment and ensure that care meets the needs of youngsters with JCA and their families. 相似文献
994.
S. Vaynman R. S. Guico M. E. Fine S. J. Manganello 《Metallurgical and Materials Transactions A》1997,28(5):1274-1276
995.
B Ali-el-Dein A Nabeeh M el-Baz S Shamaa A Ashamallah 《Canadian Metallurgical Quarterly》1997,79(5):731-735
OBJECTIVE: To compare single-dose and multiple instillations of epirubicin in the chemoprophylaxis of superficial bladder tumours. PATIENTS AND METHODS: In a prospective randomized and controlled study, 168 evaluable patients were assigned to three groups after transurethral resection of bladder tumour (TURBT) and histological confirmation of its superficial nature (pTa and pT1). The groups were comparable for tumour stage, grade and other tumour characteristics. In group 1, patients received a single dose of 50 mg epirubicin in 50 mL normal saline immediately after TURBT; group 2 received 50 mg epirubicin in 50 mL normal saline 1-2 weeks after TURBT and the instillations were repeated for 8 weeks and thereafter monthly to complete one year of treatment: group 3 (control group) received no adjuvant therapy after TURBT. The patients were assessed by cysto-urethroscopy, urine cytology and DNA flow cytometry 8 weeks after resection and then every 3 months during the first 2 years and 6 monthly thereafter during the next 2 years. Intravenous urography was performed annually and when otherwise indicated. RESULTS: The recurrence rate was significantly lower in the patients treated with epirubicin than in the control group (24, 25 and 52%, respectively; P < 0.001). In those receiving epirubicin, the rates of recurrence were statistically comparable (P = 0.9). Patients who had a large tumour burden showed slightly lower recurrence rates with single-dose epirubicin than with delayed maintenance therapy but the difference was statistically insignificant. Patients with a history of bladder tumours before treatment had lower recurrence rates with maintenance treatment than with a single dose (34.6 and 22.6% in groups 1 and 2, respectively); again this difference was statistically insignificant. Patients with grade 3 tumours showed a marginal difference in favour of maintenance therapy. The rates of progression amongst the three groups were 5.5, 3.4 and 9.3%, respectively, with no significant differences. The overall toxicity rates were comparable in the two treated groups (22 and 25%). CONCLUSION: With the possible exception of grade 3 tumours, single-dose immediate epirubicin is as effective as delayed maintenance therapy, with the advantage of being more cost-effective. 相似文献
996.
Wernicke encephalopathy is considered a complication of dialytic therapy, but there are few reports of this complication. We report a 57 years old man and a 45 years old woman, with grade IV renal failure, who after acute peritoneodialysis and chronic hemodialysis respectively, had a confusional syndrome that responded to the administration of thiamine. CT scans in both patients discarded abnormal blood collections or new cerebrovascular episodes. The man bad two previous cerebrovascular episodes, a severe anemia that was corrected, angina and an episode of arrhythmia during the dialytic procedure previous to the confusional episode. The woman had an acute uremic syndrome and a concomitant urinary tract infection during the confusional episode. Wernicke encephalopathy must be suspected in patients in dialysis with confusional episodes. 相似文献
997.
Two Ghanaian women, aged 21 and 29 years, who were involved in road traffic accidents sustaining blunt trauma to the chest and who had delayed diagnosis of their total bronchial rupture and underwent successful surgical repair 18 and 29 months, respectively after injury are reported with a review of the literature. We believe these to be the first reported cases of delayed diagnosis and successful repair of total bronchial rupture in Tropical Africa. 相似文献
998.
999.
F Goffinet B Langer B Carbonne N Berkane D Tardif F Le Goueff M Laville F Maillard 《Canadian Metallurgical Quarterly》1997,177(5):1238-1246
OBJECTIVE: Our purpose was to evaluate the feasibility of intrapartum fetal pulse oximetry, the distribution of fetal oxygen saturation values, and the relationship with the neonatal outcome in a population with an abnormal fetal heart rate. STUDY DESIGN: A prospective multicenter observational study was performed from June 1994 to November 1995. Fetal oxygen saturation was continuously recorded with use of a Nellcor N-400 fetal pulse oximeter in case of an abnormal fetal heart rate during labor. Simultaneous readings of fetal oxygen saturation and fetal blood analysis were obtained at inclusion and before birth. Feasibility, adverse effects, distribution of fetal oxygen saturation values, and relationship with neonatal outcome were assessed. RESULTS: One hundred seventy-four patients were included. From 172 attempted sensor placements, the procedure was impossible in three cases and fetal oxygen saturation values were obtained in 164 cases (95.3%). Physicians considered sensor placement an easier task than an attempt at fetal blood analysis (easy in 87.5% vs 78.9% for fetal blood analysis, p = 0.03). The mean reliable signal time (+/- SD) was 64.7% +/- 32% during the first stage. There were no serious adverse effects in the study population. The mean fetal oxygen saturation during the first stage of labor was 42.2% +/- 8.0% (10th to 90th percentile range 30% to 53%). Fetal oxygen saturation was significantly correlated with scalp pH (r = 0.29, p = 0.01) but not with neonatal umbilical artery pH or gas values. There was a significant association between low fetal oxygen saturation (< 30%) and poor neonatal condition. CONCLUSION: The feasibility of fetal pulse oximetry is satisfactory in clinical practice. It is easy to use and provides a fair rate of recorded values, even in a population with suspicion of fetal distress. A low fetal oxygen saturation is significantly associated with an abnormal neonatal outcome. 相似文献
1000.
J Müller-Ehmsen K Brixius C Schulze RH Schwinger 《Canadian Metallurgical Quarterly》1997,355(6):727-732
Insect cell lines in culture are used for a variety of studies. In this laboratory imaginal disc cell lines have been established from primary cultures from third instar larvae, and used for a number of experiments. The effect of ageing on the morphology and physiology of Drosophila cell lines has received very little attention, although problems of genotypic or phenotypic changes in cell lines with age are recognized in other areas of animal cell culture. We tested our cell line Cl8+ for any difference in growth, morphology and response to 20-hydroxyecdysone (20HE) at different ages (passage numbers). The cells were found to multiply faster, adhere less firmly to the substrate and to lose the tendency to aggregate at higher passages. The response to 20HE in terms of cell numbers and induction of beta-galactosidase was similar at all passage numbers but morphological changes in hormone-treated cells were less obvious in the higher passages. Cell lines are likely to vary in the extent of ageing effects but workers are advised to be aware of the possibilities. We suggest the effects of age on cell lines should be established, and passage numbers noted in experimental reports. 相似文献