全文获取类型
收费全文 | 1324篇 |
免费 | 0篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 4篇 |
金属工艺 | 2篇 |
建筑科学 | 2篇 |
轻工业 | 1篇 |
无线电 | 1篇 |
一般工业技术 | 1篇 |
冶金工业 | 1311篇 |
自动化技术 | 3篇 |
出版年
2020年 | 1篇 |
2011年 | 2篇 |
2007年 | 1篇 |
2006年 | 1篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2001年 | 1篇 |
1999年 | 30篇 |
1998年 | 359篇 |
1997年 | 230篇 |
1996年 | 140篇 |
1995年 | 74篇 |
1994年 | 82篇 |
1993年 | 76篇 |
1992年 | 12篇 |
1991年 | 22篇 |
1990年 | 19篇 |
1989年 | 24篇 |
1988年 | 16篇 |
1987年 | 32篇 |
1986年 | 23篇 |
1985年 | 12篇 |
1983年 | 3篇 |
1982年 | 14篇 |
1981年 | 8篇 |
1980年 | 17篇 |
1978年 | 4篇 |
1977年 | 38篇 |
1976年 | 78篇 |
1975年 | 3篇 |
1955年 | 1篇 |
排序方式: 共有1326条查询结果,搜索用时 15 毫秒
51.
EL Vodovozova GP Gayenko VI Razinkov EY Korchagina NV Bovin JG Molotkovsky 《Canadian Metallurgical Quarterly》1998,44(3):543-553
The overexpression of lectins by malignant cells was applied for in vitro targeting of liposomes equipped with a saccharide vector and loaded in the lipid phase with a lipid derivative of anticancer agent sarcolysine. The lectin specificity of human leukemia HL-60 and human lung adenocarcinoma ACL cells was revealed by tests with fluorescein-labeled sugar probes. With the help of fluorescent lipid dye it was shown that active saccharide ligands increased the level of the vectored liposome binding to malignant cells by 50-80% as compared to liposomes without vector or with inactive one. The degree of liposome/cell membrane fusion was monitored fluorometrically and was shown to be complete and independent of the vectors. The targeted drug-loaded liposomes had the cytotoxic activity 2-4 times higher as compared to the vector-free ones. 相似文献
52.
GP Bernini G Brogi GF Argenio A Moretti A Salvetti 《Canadian Metallurgical Quarterly》1998,21(5):310-317
STUDY OBJECTIVE: To determine if there are significant differences in birth outcomes and survival for infants delivered by certified nurse midwives compared with those delivered by physicians, and whether these differences, if they exist, remain after controlling for sociodemographic and medical risk factors. DESIGN: Logistic regression models were used to examine differences between certified nurse midwife and physician delivered births in infant, neonatal, and postneonatal mortality, and risk of low birthweight after controlling for a variety of social and medical risk factors. Ordinary least squares regression models were used to examine differences in mean birthweight after controlling for the same risk factors. STUDY SETTING: United States. PATIENTS: The study included all singleton, vaginal births at 35-43 weeks gestation delivered either by physicians or certified nurse midwives in the United States in 1991. MAIN RESULTS: After controlling for social and medical risk factors, the risk of experiencing an infant death was 19% lower for certified nurse midwife attended than for physician attended births, the risk of neonatal mortality was 33% lower, and the risk of delivering a low birthweight infant 31% lower. Mean birthweight was 37 grams heavier for the certified nurse midwife attended than for physician attended births. CONCLUSIONS: National data support the findings of previous local studies that certified nurse midwives have excellent birth outcomes. These findings are discussed in light of differences between certified nurse midwives and physicians in prenatal care and labour and delivery care practices. Certified nurse midwives provide a safe and viable alternative to maternity care in the United States, particularly for low to moderate risk women. 相似文献
53.
A previous magnetic resonance imaging study from our laboratory reported significant temporal lobe volume deficits in cortical gray matter, white matter, and anterior hippocampus in chronic alcoholic men relative to controls. In the present study, we reexamined these data and asked whether withdrawal seizure history was predictive of either the hippocampal or the extrahippocampal volume deficits. A review of the medical charts indicated that 11 alcoholics had experienced one or more alcohol-related seizures and 35 were seizure-free; no patient had a seizure disorder unrelated to alcohol. The two alcoholic groups did not differ significantly in age, education, alcohol consumption variables, premorbid intelligence, Memory Quotient, Trail Making, or detection of hidden figures. Although each alcoholic group showed significant bilateral volume deficits of the anterior hippocampus and frontal-parietal and temporal gray matter, relative to controls, the seizure group had significantly smaller temporal lobe white matter volumes than either the control or the seizure-free groups; the latter two groups did not differ from each other. Both alcoholic groups, however, had white matter volume deficits in the frontal-parietal region. Thus, the seizure group accounted for the white matter volume deficits in the temporal lobe previously reported in the full sample of alcoholics. It seems, then, that reduced white matter volume in the temporal lobes may be either a risk factor for or sequela of alcohol withdrawal seizures. 相似文献
54.
AJ Ryan GP Lambert X Shi RT Chang RW Summers CV Gisolfi 《Canadian Metallurgical Quarterly》1998,84(5):1581-1588
Dehydration and hyperthermia may impair gastric emptying (GE) during exercise; the effect of these alterations on intestinal water flux (WF) is unknown. Thus the purpose of this study was to determine the effect of hypohydration ( approximately 2.7% body weight) on GE and WF of a water placebo (WP) during cycling exercise (85 min, 65% maximal oxygen uptake) in a cool environment (22 degrees C) and to also compare GE and WF of three carbohydrate-electrolyte solutions (CES) while the subjects were hypohydrated. GE and WF were determined simultaneously by a nasogastric tube placed in the gastric antrum and via a multilumen tube that spanned the duodenum and the first 25 cm of jejunum. Hypohydration was attained 12-16 h before experiments by low-intensity exercise in a hot (45 degrees C), humid (relative humidity 50%) environment. Seven healthy subjects (age 26.7 +/- 1.7 yr, maximal oxygen uptake 55.9 +/- 8.2 ml . kg-1 . min-1) ingested either WP or a 6% (330 mosmol), 8% (400 mosmol), or a 9% (590 mosmol) CES the morning following hypohydration. For comparison, subjects ingested WP after a euhydration protocol. Solutions ( approximately 2.0 liters total) were ingested as a large bolus (4.6 ml/kg body wt) 5 min before exercise and as small serial feedings (2.3 ml/kg body wt) every 10 min of exercise. Average GE rates were not different among conditions (P > 0.05). Mean (+/-SE) values for WF were also similar (P > 0.05) for the euhydration (15.3 +/- 1.7 ml . cm-1 . h-1) and hypohydration (18.3 +/- 2.6 ml . cm-1 . h-1) experiments. During exercise after hypohydration, water absorption was greater (P < 0.05) with ingestion of WP (18.3 +/- 2. 6) and the 6% CES (16.5 +/- 3.7), compared with the 8% CES (6.9 +/- 1.5) and the 9% CES (1.8 +/- 1.7). Mean values for final core temperature (38.6 +/- 0.1 degrees C), heart rate (152 +/- 1 beats/min), and change in plasma volume (-5.7 +/- 0.7%) were similar among experimental trials. We conclude that 1) hypohydration to approximately 3% body weight does not impair GE or fluid absorption during moderate exercise when ingesting WP, and 2) hyperosmolality (>400 mosmol) reduced WF in the proximal intestine. 相似文献
55.
56.
57.
58.
59.
GP Rossi E Pavan M Chiesura-Corona F Rea A Poletti AC Pessina 《Canadian Metallurgical Quarterly》1994,7(10):1893-1898
Bronchocentric granulomatosis (BCG) is a rare chronic granulomatous lung disease that leads to destruction of the airway walls. It has been observed in association with various conditions, but never, so far, been reported to involve the central nervous system. We report a case of histologically confirmed pulmonary bronchocentric granulomatosis temporally associated with a partial central diabetes insipidus (CDI). Although the pathological basis of the posterior pituitary gland involvement was not ascertained, the temporal association of bronchocentric granulomatosis and central diabetes insipidus, as well as the fact that corticosteroid treatment provided stable remission of both conditions after a 10 month follow-up, strongly suggest that central diabetes insipidus was aetiologically related to bronchocentric granulomatosis in this patient. 相似文献
60.
GP Ferguson AD Chacko CH Lee IR Booth C Lee 《Canadian Metallurgical Quarterly》1996,178(13):3957-3961
Expression of the Kdp system sensitizes cells to methylglyoxal (MG) whether this electrophile is added externally or is synthesized endogenously. The basis of this enhanced sensitivity is the maintenance of a higher cytoplasmic pH (pHi) in cells expressing Kdp. In such cells, MG elicits rapid cytoplasmic acidification via KefB and KefC, but the steady-state pHi attained is still too high to confer protection Lowering pHi further by incubation with acetate increases the sensitivity of cells to MG. 相似文献