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21.
BACKGROUND: Some studies have suggested that the use of calcium channel blockers may increase the risk of cancer. A possible association of the use of calcium channel blockers with cancer incidence and cancer mortality was addressed using data from the Nurses' Health Study. METHODS: In this study, a total of 18,635 female nurses reported regularly taking at least 1 of 4 cardiovascular medications in 1988: diuretics, beta-blockers, calcium channel blockers, and/or angiotensin-converting enzyme (ACE) inhibitors. Cancer incidence and cancer deaths were ascertained until 1994. RESULTS: During 6 years of follow-up, 852 women were newly diagnosed with cancer and 335 women died of cancer. Women who reported the use of calcium channel blockers had no increased risk of newly diagnosed cancer compared with those taking other cardiovascular drugs (relative risk=1.02; 95% CI 0.83-1.26). The relative risk of dying from cancer associated with the self-reported use of calcium channel blockers was 1.25 (95% CI 0.91-1.72). Relative risks were adjusted for the following self-reported factors: age; weight; height; cholesterol level; systolic and diastolic blood pressure; smoking; alcohol intake; physical activity; menopausal status; postmenopausal hormone use; aspirin use; and history of diabetes, cancer, stroke, myocardial infarction, coronary artery bypass graft or percutaneous transluminal coronary angioplasty, angina, and hypertension. Regarding site specific cancer incidence and mortality, only lung cancer incidence was somewhat increased (RR=1.61; 95% CI 0.88-2.96). CONCLUSIONS: These data suggest no important increase in overall cancer incidence or cancer mortality related to the self-reported use of calcium channel blockers.  相似文献   
22.
BACKGROUND: Parity and long term use of oral contraceptives have been associated consistently with a decreased risk of ovarian cancer. However, previous reports of the relationship of other reproductive factors (time since first use or last use of oral contraceptives, age at menarche or menopause, age at first birth) with ovarian cancer have been inconsistent. METHODS: The authors studied these relationships in the Nurses' Health Study, a prospective cohort study of 121,700 female registered nurses aged 30-55 years in 1976 when the study began. From 1976 to 1988, 260 cases of confirmed epithelial ovarian cancer occurred among 1.2 million person-years of follow-up. RESULTS: A statistically significant inverse association was observed between parity and ovarian cancer risk (relative risk [RR] = 0.84; 95% confidence interval [CI] = 0.77-0.91 per pregnancy); age at first birth was not associated independently with risk. In age-adjusted analyses, a significant inverse association was noted between long term use of oral contraceptives and ovarian cancer, which was no longer significant after controlling for other ovarian cancer risk factors (RR with > or = 5 years' use: 0.65; 95% CI = 0.40-1.05). After control for duration of use, a weak nonsignificant inverse association was observed with time since first oral contraceptive use and no independent effect of time since last use. Neither age at menarche nor age at menopause was associated significantly with ovarian cancer risk. CONCLUSIONS: In this large prospective study, parity was the only reproductive factor that had a substantial independent association with ovarian cancer. Long term oral contraceptive use also appeared to have an inverse relationship with ovarian cancer, although this association was of borderline significance (P = 0.11) after adjustment for other risk factors.  相似文献   
23.
Death from myocardial infarction (MI) in India is exacerbated by smoking of bidis or cigarettes. Smoking among 309 men with incident MI was compared to 618 age matched controls; 56% of the individuals with MI and 26% of controls were current smokers. Current smokers had a relative risk of 4.7 (95% confidence interval (CI) 3.2 to 6.9) compared to never smokers. Relative risks for smoking more than 10 cigarettes or 10 bidis daily were 9.1 (95% CI 4.7 to 17.7) and 8.1 (95% CI 4.3 to 15.3), respectively. It is estimated that smoking may cause 53% (95% CI 47% to 64%) of MIs among urban males in India.  相似文献   
24.
Metabolic and nutritional complications of urinary diversion through bowel or stomach segments are common, but fortunately, not often severe. When metabolic abnormalities are problematic, deterioration or baseline insufficiency in renal function is the most likely cause. Deterioration is most commonly associated with obstruction or infection. The urologist should be acutely aware of the potential for metabolic derangements when the prediversion creatinine is greater than 2.0 mg/dL. In this situation, the urologist should employ the basic principles in this article when planning the procedure in order to minimize metabolic complications and morbidities. In the setting of significant renal insufficiency, a short colon or ileal conduit would likely be superior to an ileal or colonic neobladder, or a diversion, incorporating a large gastric segment. Furthermore, in the absence of symptomatic metabolic abnormalities, we advocate treatment of minor laboratory abnormalities, particularly acidosis, to reduce the incidence of metabolic bone disease. Nutritional and gastrointestinal complications are treated on an "as needed" basis, with the exception of metabolic bone disease, which we would hope to prevent with alkalinization and Vitamin C supplementation. Some of the nutritional and gastrointestinal complications are best avoided by leaving the ileocecal valve intact, or by minimizing the use of certain segments. Some evidence exists that over time, histologic changes in the epithelium of diversion segments may impair absorption and contribute to greater resistance against metabolic derangements. Whether the changes truly reduce the incidence of metabolic abnormalities remains to be studied. The ideal, complication-free, diversion with universal application does not exist; however, the urologist must strive to select an option that will provide a functional result for the patient with minimal associated morbidity.  相似文献   
25.
Support for separation of roles is decisive towards a successful business ecosystem where various stakeholders with dedicated expertises network and collaborate. However, it depends on means for composition(system of systems, reuse of black boxes). This paper proposes Dynamic State Charts as an extension of state charts for composition and coordination of complex robot behavior which is one of the challenges in service robotics. Their states allow to refine their content by choosing from a set of alternative matching state instances for robust task execution and to manage the complexity of real-world tasks. Dynamic State Charts allow reuse and can be bundled with software components and are provided in a repository (idea of an “robot app store”) as a step towards composition and separation of roles as necessary for a business ecosystem in service robotics. The approach is demonstrated in a practical application with a service robot.  相似文献   
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BACKGROUND: The purpose of this study was to examine prospectively the relation of shift work to risk of coronary heart disease (CHD) in a cohort of women. METHODS AND RESULTS: An ongoing prospective cohort of US female nurses, in whom we assessed (in 1988) the total number of years during which they worked rotating night shifts (at least three nights per month in addition to day and evening shifts), included 79,109 women, 42 to 67 years old in 1988, who were free of diagnosed CHD and stroke. Incident CHD was defined as nonfatal myocardial infarction and fatal CHD. During 4 years of follow-up (1988 to 1992), 292 cases of incident CHD (248 nonfatal myocardial infarction and 44 fatal CHD) occurred. The age-adjusted relative risk of CHD was 1.38 (95% CI, 1.08 to 1.76) in women who reported ever doing shift work compared with those who had never done so. The excess risk persisted after adjustment for cigarette smoking and a variety of other cardiovascular risk factors. Compared with women who had never done shift work, the multivariate adjusted relative risks of CHD were 1.21 (95% CI, 0.92 to 1.59) among women reporting less than 6 years and 1.51 (95% CI, 1.12 to 2.03) among those reporting 6 or more years of rotating night shifts. CONCLUSIONS: These data are compatible with the possibility that 6 or more years of shift work may increase the risk of CHD in women.  相似文献   
28.
We report tunneling spectroscopy experiments on a bilayer graphene double quantum dot device that can be tuned by all-graphene lateral gates. The diameter of the two quantum dots are around 50 nm and the constrictions acting as tunneling barriers are 30 nm in width. The double quantum dot features additional energies on the order of 20 meV. Charge stability diagrams allow us to study the tunable interdot coupling energy as well as the spectrum of the electronic excited states on a number of individual triple points over a large energy range. The obtained constant level spacing of 1.75 meV over a wide energy range is in good agreement with the expected single-particle energy spacing in bilayer graphene quantum dots. Finally, we investigate the evolution of the electronic excited states in a parallel magnetic field.  相似文献   
29.
Spatially resolved Raman spectroscopy of single- and few-layer graphene   总被引:1,自引:0,他引:1  
We present Raman spectroscopy measurements on single- and few-layer graphene flakes. By using a scanning confocal approach, we collect spectral data with spatial resolution, which allows us to directly compare Raman images with scanning force micrographs. Single-layer graphene can be distinguished from double- and few-layer by the width of the D' line: the single peak for single-layer graphene splits into different peaks for the double-layer. These findings are explained using the double-resonant Raman model based on ab initio calculations of the electronic structure and of the phonon dispersion. We investigate the D line intensity and find no defects within the flake. A finite D line response originating from the edges can be attributed either to defects or to the breakdown of translational symmetry.  相似文献   
30.
Lyophilised cells of various Rhodococcus spp. were employed in an efficient hydrogen transfer‐like process for the asymmetric bioreduction of heteroaryl methyl ketones using 2‐propanol as hydrogen donor. Besides the genus Rhodococcus, only Mycoplana rubra R14 showed a comparable stability towards elevated concentrations of the co‐substrate 2‐propanol. Among the organisms tested, Rhodococcus ruber DSM 44541 and DSM 43338 showed best activity and selectivity. With these strains, the reaction proceeded with high stereoselectivity (ee>99%) and predictable stereochemical outcome regardless of the nature of the heteroaromatic ring system. The reaction could be performed at the exceptional substrate concentration of up to 0.4 mol L−1 in an environmentally friendly aqueous‐organic solvent mixture at room temperature and is easy to handle, thus providing a very practical tool to access enantiopure 1‐heteroarylethanols.  相似文献   
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