全文获取类型
收费全文 | 1011篇 |
免费 | 3篇 |
专业分类
化学工业 | 10篇 |
金属工艺 | 2篇 |
机械仪表 | 5篇 |
轻工业 | 7篇 |
水利工程 | 1篇 |
无线电 | 10篇 |
一般工业技术 | 16篇 |
冶金工业 | 957篇 |
原子能技术 | 2篇 |
自动化技术 | 4篇 |
出版年
2021年 | 1篇 |
2020年 | 2篇 |
2018年 | 2篇 |
2016年 | 2篇 |
2014年 | 1篇 |
2013年 | 8篇 |
2012年 | 2篇 |
2011年 | 2篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 2篇 |
2007年 | 1篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 30篇 |
1998年 | 296篇 |
1997年 | 166篇 |
1996年 | 101篇 |
1995年 | 63篇 |
1994年 | 72篇 |
1993年 | 56篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 9篇 |
1980年 | 13篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 31篇 |
1976年 | 70篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有1014条查询结果,搜索用时 15 毫秒
931.
CE Blane JT Fitzgerald RA Bowerman AE Schlesinger ML Barclay GB Zelenock M McQuillan WK Davis 《Canadian Metallurgical Quarterly》1996,3(11):958-961
RATIONALE AND OBJECTIVES: Clinical competence certification is now required in some specialties in medicine. A Comprehensive Clinical Assessment (CCA) was created to test mastery of critical skills by students at the end of the 3rd year of medical school. METHODS: The CCA is a series of stations that test skills the faculty consider important for all medical students (eg, breast examination, electrocardiogram reading, chest pain assessment, ophthalmology photographs). The radiology station was designed to evaluate imaging skills believed to be taught and learned in the core 3rd-year rotations. RESULTS: External measures (National Board Examinations, grade point average, and overall score) of clinical performance of the 608 medical students who completed the CCA examination between 1991 and 1993 were found to be correlated with the radiology station scores. CONCLUSION: The radiology station in the CCA examination is a reproducible measure of clinical performance. 相似文献
932.
933.
Recommended culture methods for monitoring bacterial contamination of H2O, dialysate and bicarbonate concentrate in dialysis centers in the USA involves culturing these fluids for 48 h at 37 degrees C. A variety of media and commercial culture methods are accepted for monitoring these fluids. Over a 3-month a comparison was made between an acceptable culture method, tryptic soy agar (TSA) employing the pour plate (PP) technique at 37 degrees C for 48 h, and PP cultures on standard methods agar (SMA) and R2A agar, incubated at ambient temperature (23 degrees C) for 48, 72, 168 h. Increases in the colony counts over time occurred for all three fluids. However, counts wee greater on SMA and R2A than on TSA. The increases over the standard 48-hour TSA cultures ranged as high as 10(4) times for 23 degrees C cultures at 7 days of incubation. Endotoxin levels even in the most contaminated samples were found to be below the acceptable 5 EU/ml recommended for reprocessor water. Bacterial colonies that appeared at 48, 72 and 168 h were isolated and identified. Pseudomonas, Moraxella, Acinetobacter and CDC group VI C-2 were among some of the common bacteria isolated. This study indicates that the media utilized, the time and temperature of incubation may result in a significant underestimation of the bacterial population of water and dialysis fluids, thus potentially placing the patient at a higher risk. 相似文献
934.
F Gao CK Sun JM Pei YM Wang Y Li GB Niu YM Zang 《Canadian Metallurgical Quarterly》1996,31(10):727-731
To study the effects of batroxobin on coronary circulation and cardiac performance in acute myocardial ischemia, Batroxobin was given intravenously to dogs with experimental coronary stenosis. A dose-dependent increase of coronary blood flow (CBF) was observed. Forty minutes after batroxobin (2 BU.kg-1 at infusion rate 0.1 BU.kg-1.min-1) administration, CBF increased by 12% (P < 0.05), small coronary resistance(RS) decreased from 4.1 +/- 0.5 to 3.2 +/- 0.5 mmHg.min.ml-1 (P < 0.01), while large coronary resistance(RL) changed insignificantly from 3.9 +/- 0.8 to 3.8 +/- 0.7 mmHg.min.ml-1 (P > 0.05). Two hours following drug administration, the changes in CBF, RS and RL still remained and RT decreased by 13% (P < 0.05). The + LV(dp/dt)max and -LV(dp/dt)max increased by 14% and 16% (P < 0.05) respectively compared with those in control group. It is concluded that batroxobin improves the ischemic canine coronary circulation and cardiac performance by way of lowering the small coronary resistance and thus increasing CBF. The data also suggest the benificial effect of batroxobin in acute myocardial ischemia. 相似文献
935.
936.
FW Edens RA Qureshi CR Parkhurst MA Qureshi GB Havenstein IA Casas 《Canadian Metallurgical Quarterly》1997,76(12):1665-1673
Two colonial types (1 and 2) of Escherichia coli are represented predominantly in cultures isolated from turkey poults with poult enteritis and mortality syndrome (PEMS). Biotype codes determined using two systems (BBL: 36570 and 34560 for colony types 1 and 2, respectively; API-20E: 5144572 and 5144512 for colony types 1 and 2, respectively) clearly establish these organisms as E. coli. These isolates were not clearly divergent from the general profile for E. coli, but colony type 2 differs from colony type 1 with regard to its negative reactions for ornithine decarboxylase and the fermentation of dulcitol, rhamnose, sucrose, and melibiose, suggesting that it is atypical. Colony type 1 is nonserotypable and nonmotile, whereas colony type 2 is serotyped as O136: motile because it has H antigens associated with flagella. Capsular antigens were not found, but thin capsules were seen on cells from both colony types in stained preparations. Cultural morphology was different with colony type 1 having a circular, mucoid, raised morphology and colony type 2 having an irregular, flat, rough morphology. Colony type 1 has a doubling time at 37 C of about 20 min, whereas colony type 2 doubles in 30 min. Furthermore, colony type 1 is a potent colicin producer, but colony type 2 is not a colicin producer. Both E. coli isolates have resistance profiles for multiple antibiotics. Each strain responds to third generation fluoroquinolone antibiotics by changing their biotypes and become resistant after culturing once in their presence. These E. coli are proposed as possible etiological links in the complex series of events that take place in poults susceptible to PEMS. 相似文献
937.
Differences in cord serum low density lipoprotein (LDL) composition between male and female neonates with normal or high (> or = 100 mg/dl or > or = 2.59 mmol/l) serum cholesterol levels were studied in 548 full-term newborn infants of the Toledo Study (Spain), where the absence of known perinatal factors that would alter lipid levels in cord blood was confirmed. The percentage of females with a high serum total cholesterol (TC) level was higher (p < 0.02) than that of males. ANOVA two-way analysis shows significant interaction of gender and cholesterol level upon LDL-cholesterol, triglycerides and LDL-cholesterol/Apoprotein (Apo) B ratio. However, Apo B was higher in those neonates, both male and female, with high cholesterol levels. The LDL fraction carried about 55% of TC in females with high TC levels (HF), whereas it transported just 40% in males with high TC levels (HM). LDL appeared more enriched in cholesterol than in Apo B in HF than in HM (p < 0.01). An increased level of small LDL particles should be associated with the higher triglyceride level found amongst HM. Results in LDL composition suggest that metabolic gender-related differences in infants with normal or high TC are presented at birth. 相似文献
938.
GB Mychaliska JF Bealer JL Graf MA Rosen NS Adzick MR Harrison 《Canadian Metallurgical Quarterly》1997,32(2):227-30; discussion 230-1
While treating eight fetuses with predictable airway obstruction, the authors developed a systematic approach, the ex utero intrapartum treatment procedure, to secure the airway during delivery. Six patients had their trachea plugged or clipped in utero for treatment of congenital diaphragmatic hernia, and two patients had prenatally diagnosed cystic hygroma of the neck and oropharynx. The ex utero intrapartum treatment procedure was performed by using high doses of inhaled halogenated agents to facilitate uterine relaxation during cesarean section, securing the fetal airway while feto-placental circulation remained intact, and then dividing the umbilical cord. A variety of procedures were performed during the ex utero intrapartum treatment procedure including bronchoscopy, orotracheal intubation, tracheostomy, tracheostomy with retrograde orotracheal intubation, tracheoplasty, removal of internal tracheal plug, removal of external tracheal clip, central line placement, and instillation of surfactant. There were minimal maternal or fetal complications during the procedure. This approach requires the coordinated efforts of pediatric surgeons, obstetricians, anesthesiologists, sonographers, and neonatologists. The combination of intensive maternal-fetal monitoring, cesarean section with maximal uterine relaxation, and maintenance of intact feto-placental circulation provides a controlled environment for securing the airway in babies with prenatally diagnosed airway obstruction. 相似文献
939.
Comparisons of the oscillatory shear viscoelasticity and composition of pathological synovial fluids
Rheological and compositional properties of pathological synovial fluids were measured and compared in order to reveal differences between disease states. The cases include degenerative joint disease, rheumatoid arthritis, mixed connective tissue disease, and pseudogout. Using an oscillatory flow capillary instrument, measurements were made of both the frequency and shear rate dependence of the complex viscoelasticity. The fluid types differ most in their elasticity, with the degenerative joint disease fluids having the greatest average viscosity, elasticity and intrinsic viscosity, followed by the rheumatoid arthritis fluids, and the fluids from cases of mixed connective tissue disease. Differences in the hyaluronate and protein concentrations are not as great as those between rheological variables. The viscoelasticity of synovial fluid appears more strongly dependent on the degree of polymerization of hyaluronate than on its concentration. These synovial fluids conform well to a model of relaxation process truncation. Distinct types of elastic stress-strain behavior reveal the nature of the dynamic fluid structure. 相似文献
940.