全文获取类型
收费全文 | 1053篇 |
免费 | 14篇 |
专业分类
化学工业 | 5篇 |
金属工艺 | 1篇 |
机械仪表 | 2篇 |
建筑科学 | 2篇 |
能源动力 | 3篇 |
轻工业 | 4篇 |
无线电 | 33篇 |
一般工业技术 | 35篇 |
冶金工业 | 969篇 |
自动化技术 | 13篇 |
出版年
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 5篇 |
2012年 | 3篇 |
2011年 | 5篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 7篇 |
2007年 | 4篇 |
2006年 | 7篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1999年 | 25篇 |
1998年 | 292篇 |
1997年 | 169篇 |
1996年 | 108篇 |
1995年 | 54篇 |
1994年 | 63篇 |
1993年 | 58篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 15篇 |
1989年 | 10篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1986年 | 1篇 |
1985年 | 6篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 10篇 |
1978年 | 5篇 |
1977年 | 35篇 |
1976年 | 80篇 |
1975年 | 3篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有1067条查询结果,搜索用时 15 毫秒
871.
AIM: To compare the proposed diagnostic criteria of subacute infectious endocarditis (SIE) to criteria developed by von Reyn et al. and by Duke Endocarditis Service. MATERIALS AND METHODS: 69 SIE cases and suspected recurrences have been analysed for patients observed in the Therapeutic Clinic of the Moscow medical University in 1990-1997. RESULTS: According to the authors' criteria accurate and tentative SIE diagnosis were made in 82 and 18% of patients, respectively. The other two diagnostic approaches in this situation increase the percentage of presumptive diagnosis and decrease that of the definite one. CONCLUSION: The criteria proposed by the authors are more sensitive in diagnosis of definite SIE, are less dependent on echocardiography quality and bacteriological diagnosis. 相似文献
872.
873.
Immunogenicity of immunostimulating complexes of Japanese encephalitis virus in experimental animals
Immunogenicity of immunostimulating complexes (ISCOMs) of Japanese encephalitis virus (JEV) were studied in mice, rabbits and monkeys. Two doses of JE ISCOMs elicited a strong immune response in mice with an uniform distribution in IgG subclasses. Different time intervals between the two doses of ISCOMs led to similar titers of antibodies. Rabbits and monkeys immunized with ISCOMs developed strong neutralizing immune, response. Mice immunized with ISCOMs demonstrated cell-mediated immunity (CMI) as evidenced by T cell proliferation and macrophage migration inhibition (MMI) assays. 相似文献
874.
LR Simkin-Silverman RR Wing MA Boraz EN Meilahn LH Kuller 《Canadian Metallurgical Quarterly》1998,4(3):255-271
This paper proposes and defends the small worlds hypothesis, which states that expert physicians organize diagnostic knowledge on the basis of similarities between disease categories, forming 'small worlds' consisting of small subsets of diseases and their distinguishing features. Examining existing data from several previous studies, the authors provide support for the small worlds hypothesis and for a characterization of the process of expert medical diagnostic reasoning as a succession of limited comparisons involving related diagnostic hypotheses. In one study, subjects were presented clinical endocrine cases one statement at a time and were prompted to think aloud after presentation of each statement. A combination of discourse and protocol analysis techniques were used to investigate hypothesis generation and evaluation. In another study, dialogues from doctor-patient interviews were examined. It was found that expert subjects rapidly select relatively small sets of plausible diagnostic hypotheses (small worlds) and focus on the most relevant medical findings that distinguish among the diseases in such small worlds. Results from both studies indicate that expert physicians use efficient strategies for discriminating among these alternative hypotheses in a stepwise process. In contrast, non-experts often generate large numbers of possible diagnostic hypotheses, belonging to widely differing disease categories. The results provide empirical support for the theoretical basis of small worlds. The implications of these results for the study of medical expertise and knowledge engineering are discussed, as well as considerations for the development of decision support systems. 相似文献
875.
PK Sneed MW Dewhirst T Samulski J Blivin LR Prosnitz 《Canadian Metallurgical Quarterly》1998,40(5):1015-1017
This study was performed to determine whether premedication with midazolam and fentanyl prevents reliable detection of an i.v. lidocaine test dose. Thirty ASA physical status I or II patients received either 3 mL of saline or 1.5 mg of midazolam (1.5 mL) plus 75 microg of fentanyl (1.5 mL) i.v. in a randomized, double-blind fashion. Five minutes later, lidocaine 1 mg/kg was injected i.v. At 1.5 min before and every minute after lidocaine administration, each subject was questioned regarding the presence of four symptoms of systemic lidocaine toxicity. Any new tinnitus, perioral numbness, metallic taste, or light-headedness within 5 min after lidocaine administration was considered a positive response. All 15 patients in the saline group (100% sensitivity) had a positive response to i.v. lidocaine, but only 9 of 15 patients in the sedation group had a positive response (60% sensitivity; P = 0.017). We conclude that midazolam and fentanyl premedication decreases the reliability of subjective detection of i.v. lidocaine. Implications: Anesthesiologists often rely on subjective symptoms to prevent local anesthetic toxicity while performing regional anesthesia. Sedatives are often administered during the administration of regional anesthesia. This study demonstrates that typical sedation decreases the reliability of detection of local anesthetic toxicity by subjective symptoms. 相似文献
876.
877.
This review provides the generalist with a simple means of approaching the diagnosis and treatment of connective tissue diseases. A concise summary of autoimmune laboratory panels and their relevance in the diagnosis of Lupus, Dermatomyositis, Mixed Connective Tissue Disease, and Sclerodermatous Diseases is provided. 相似文献
878.
LR Jalbert ED Rosen L Moons JC Chan P Carmeliet D Collen FJ Castellino 《Canadian Metallurgical Quarterly》1998,102(8):1481-1488
Matings of mice heterozygous for a protein C (PC) deficient allele, produced by targeted PC gene inactivation, yielded the expected Mendelian distribution of PC genotypes. Pups with a total deficiency of PC (PC-/-), obtained at embryonic day (E) 17.5 and at birth, appeared to develop normally macroscopically, but possessed obvious signs of bleeding and thrombosis and did not survive beyond 24 h after delivery. Microscopic examination of tissues and blood vessels of E17.5 PC-/- mice revealed their normal development, but scattered microvascular thrombosis in the brain combined with focal necrosis in the liver was observed. In addition, bleeding was noted in the brain near sites of fibrin deposition. The severity of these pathologies was exaggerated in PC-/- neonates. Plasma clottable fibrinogen was not detectable in coagulation assays in PC-/- neonatal mice, suggestive of fibrinogen depletion and secondary consumptive coagulopathy. Thus, while total PC deficiency did not affect the anatomic development of the embryo, severe perinatal consumptive coagulopathy occurred in the brain and liver of PC-/- mice, suggesting that a total PC deficiency is inconsistent with short-term survival. 相似文献
879.
LR Gentry 《Canadian Metallurgical Quarterly》1994,191(1):1-17
The endocrinology of late gestation and parturition in the mare has been described, but unlike other domestic animal species, the factors that initiate parturition in the mare have not been elucidated. In contrast to ruminant species, maternal estrogen and progesterone concentrations do not change markedly, and a well-defined fetal cortisol surge is not observed just prior to parturition in the mare. Parturition is associated with large increases in prostaglandin and oxytocin concentrations, which induce uterine contractions and delivery of the foal. There are many methods of inducing parturition in term mares, but the most popular and safest method is through the administration of low-dose oxytocin. 相似文献
880.
RD Rondinelli LR Robinson KM Hassanein WC Stolov WY Fujimoto DE Rubner 《Canadian Metallurgical Quarterly》1994,73(2):116-123
BACKGROUND: According to the D2 dopamine receptor hypothesis of schizophrenia, there is an increased number of D2 receptors in the brains of schizophrenic patients than in those of healthy controls. We tested this hypothesis in 13 newly admitted neuroleptic-naive schizophrenic patients and 10 healthy volunteers using positron emission tomography. METHOD: The quantification of striatal D2 dopamine receptor density (Bmax) and affinity (Kd) was done using an equilibrium model described for raclopride labeled with carbon 11. RESULTS: No statistically significant alterations were found in D2 receptor densities or affinities between the patient and control groups. However, a subgroup of four patients with a relatively high striatal D2 dopamine density was identified. Two patients, especially, had D2 dopamine densities almost twice as high as the mean control Bmax value. The Kd values also tended to be higher in this subset of patients than in the controls. No consistent striatal D2 dopamine receptor laterality was observed in schizophrenic patients or controls. However, an association of high D2 dopamine density in the left striatum and the mass of raclopride injected in the scan with low-specific radioactivity was observed in patients but not in controls. CONCLUSIONS: There are no general changes in D2 dopamine receptor Bmax or Kd values in neuroleptic-naive schizophrenics, but there may be a subgroup of patients with aberrant striatal D2 dopamine receptor characteristics in vivo. 相似文献