全文获取类型
收费全文 | 986篇 |
免费 | 8篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 24篇 |
金属工艺 | 6篇 |
建筑科学 | 3篇 |
矿业工程 | 1篇 |
轻工业 | 15篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 34篇 |
一般工业技术 | 27篇 |
冶金工业 | 845篇 |
原子能技术 | 3篇 |
自动化技术 | 32篇 |
出版年
2023年 | 5篇 |
2022年 | 3篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 7篇 |
2016年 | 3篇 |
2014年 | 2篇 |
2013年 | 15篇 |
2012年 | 3篇 |
2011年 | 9篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 5篇 |
2007年 | 5篇 |
2006年 | 2篇 |
2005年 | 9篇 |
2004年 | 4篇 |
2003年 | 10篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 29篇 |
1998年 | 239篇 |
1997年 | 129篇 |
1996年 | 81篇 |
1995年 | 48篇 |
1994年 | 43篇 |
1993年 | 46篇 |
1992年 | 12篇 |
1991年 | 21篇 |
1990年 | 17篇 |
1989年 | 25篇 |
1988年 | 18篇 |
1987年 | 23篇 |
1986年 | 13篇 |
1985年 | 22篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 12篇 |
1979年 | 2篇 |
1978年 | 6篇 |
1977年 | 23篇 |
1976年 | 53篇 |
1975年 | 5篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1965年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有994条查询结果,搜索用时 46 毫秒
1.
Belcher Calvin H. Zheng Baolong MacDonald Benjamin E. Langlois Eric D. Lehman Benjamin Pearce Charles Delaney Robert Apelian Diran Lavernia Enrique J. Monson Todd C. 《Journal of Materials Science》2022,57(9):5518-5532
Journal of Materials Science - For transformers and inductors to meet the world’s growing demand for electrical power, more efficient soft magnetic materials with high saturation magnetic... 相似文献
2.
3.
4.
Uses principles of latent trait theory to derive conditions under which mean differences on an observed variable are indicative of mean differences on an underlying construct, focusing on the logistic curve as a model for describing the relation between the observed variable and construct. In this situation, and with normally distributed scores on the construct, a t test comparing groups on the observed variable produces correct inferences at the construct level only if group variances on the construct are homogeneous or the difficulty level of the test equals the mean ability level of the examinees. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
We introduce a generalization of a deterministic relaxation algorithm for edge-preserving regularization in linear inverse problems. This algorithm transforms the original (possibly nonconvex) optimization problem into a sequence of quadratic optimization problems, and has been shown to converge under certain conditions when the original cost functional being minimized is strictly convex. We prove that our more general algorithm is globally convergent (i.e., converges to a local minimum from any initialization) under less restrictive conditions, even when the original cost functional is nonconvex. We apply this algorithm to tomographic reconstruction from limited-angle data by formulating the problem as one of regularized least-squares optimization. The results demonstrate that the constraint of piecewise smoothness, applied through the use of edge-preserving regularization, can provide excellent limited-angle tomographic reconstructions. Two edge-preserving regularizers-one convex, the other nonconvex-are used in numerous simulations to demonstrate the effectiveness of the algorithm under various limited-angle scenarios, and to explore how factors, such as the choice of error norm, angular sampling rate and amount of noise, affect the reconstruction quality and algorithm performance. These simulation results show that for this application, the nonconvex regularizer produces consistently superior results. 相似文献
6.
M Al-Sarraf TF Pajak RW Byhardt JJ Beitler MM Salter JS Cooper 《Canadian Metallurgical Quarterly》1997,37(4):777-782
PURPOSE: Despite aggressive surgery and postoperative radiation therapy, only 30% of patients who have advanced, potentially resectable carcinomas of the head and neck survive for 5 years. In the hope of improving this situation we studied the effect of postoperative radiotherapy delivered concurrently with cisplatin. METHODS AND MATERIALS: Patients who had Stage IV tumors and/or involved surgical margins received 60 Gy in 30 fractions over 6 weeks plus 100 mg/m2 of cisplatin on radiotherapy days 1, 23 and 43. Fifty-two patients participated in this trial and 51 were evaluated. Forty-three (84%) patients had pathologic T3 or T4 disease, 43 (84%) had Stage IV disease, and 27 (53%) had histologically involved surgical margins. RESULTS: Severe and life-threatening toxicities occurred in 20% and 12% of patients, respectively; the most common drug-related toxicities were leukopenia, anemia, nausea, and vomiting. Seventeen patients (43%) remain alive with no evidence of disease. Four patients (8%) died with no evidence of neoplastic disease, and one patient has died of a second independent malignancy. By actuarial analysis at 3 years, 48% of patients are alive, 81% have locoregional control of disease, and 57% are free of distant metastases. CONCLUSIONS: Based on comparison with similar patients treated in a prior Radiation Therapy Oncology Group/Intergroup trial (RTOG), we conclude that postoperative radiotherapy with concurrent cisplatin may improve locoregional control rates and should be prospectively tested. 相似文献
7.
In the last decades, the classification of schemes of haematological malignancies have undergone considerable changes both in terms of modifications of previous concepts and of methodological approaches, in parallel with the acquisition of new information on the physiopathological and functional pattern of haemic cells and of their precursors both at the lymph node and bone marrow level. The cyto-morphological aspects of haemic were better defined and integrated by the application of cyto- and histochemical methods, which were subsequently supplemented by bioenzymatic and cytogenetic techniques, then by immunophenotypical studies and finally by biomolecular investigations. Through the use of monoclonal antibodies and the introduction both in research and routine diagnostic practice of multiparameter analysis techniques, it is now possible to correlate several cellular parameters, to identify clonality of malignant cells as well as their lineage assignment and maturation stage. Flow cytometry has become an important, rapid and objective method for the diagnosis of haematological neoplasias. In the present survey we have illustrated the different expression of surface, cytoplasmic and nuclear antigens in haematological malignancies, their correlation with the clinical course of the disease and their diagnostic and prognostic significance. 相似文献
8.
Self-selected food intake of 15 reduced-obese women living in a metabolic ward was studied for 14 consecutive days to determine the effect of exercise and other metabolic and behavioral variables on energy intake. A choice of prepared food items were offered at breakfast, lunch and dinner, and a variety of additional food items were available continuously 24 h/day. Subjects performed either moderate intensity aerobic exercise (A-EX) (n = 8) expending 354 +/- 76 kcal/session or low intensity resistance weight training (R-EX)(n =7) expending 96 +/- kcal/session, 5 days/week. Mean energy intakes (kcal/day, +/- SEM) of the exercise groups were similar: 1867 +/- 275 for A-EX, 1889 +/- 294 for R-EX. Mean energy intakes of individuals ranged from 49 to 157% of the predetermined level required for weight maintenance. Resting metabolic rate per kg 0.75 and the Eating Inventory hunger score contributed significantly to the between subject variance in energy intake, whereas exercise energy expenditure did not. Regardless of exercise, eight women consistently restricted their energy intake (undereaters), and seven other consumed excess energy (overeaters). Overeaters were distinguished by higher Eating Inventory disinhibition (P = 0.023) and hunger (p = 0.004) scores. The overeaters' diet had a higher fat content 34 +/- 1% (p = 0.007). Also, overeaters took a larger percentage of their daily energy, than that of undereaters, 27 +/- 1 energy intake in the evening, 13 +/- 2%, compared to undereaters, 7 +/- 1% (p = 0.005). We conclude that the Eating Inventory is useful for identifying reduced-obese women at risk of overeating, and these individuals may benefit from dietary counseling aimed at reducing fat intake and evening snacking. 相似文献
9.
TF Tihanyi K Morvay L Nehéz T Winternitz Z Rusz LE Flautner 《Canadian Metallurgical Quarterly》1997,36(1-4):359-361
Management of the pancreatic diseases is still a challenge to the laparoscopic technique. Some experience has been gained in the laparoscopic exploration of the pancreas and staging in cancer. Anatomically the accessibility of the distal pancreas provides the laparoscopic approach technically feasible. Patient and method: A case of insuloma in the tail of the pancreas is presented, where distal pancreatic resection was performed laparoscopically with the preservation of the spleen. In a 55 years old female patient with typical clinical symptoms of hyperinsulinism CT identified a 3 cm large solid tumor in the tail of the pancreas. Complete mobilization of the distal pancreas was enhanced by the use of an ultrasonic dissector (UltraCision). The pancreas is detached from the splenic hilum after dividing the spleen vessels. The pancreas is transected proximally by laparoscopic linear stapler. Preservation of the short gastric vessels provides the necessary blood supply of the spleen following division of the splenic artery and vein. Thus removal of the spleen is not a necessary step in this procedure. The operation was carried out within 4.5 hours. Postoperative course was uneventful, the patient left the hospital on the 5th postoperative day. Advantages of the procedure were the earlier mobilization and shorter recovery time, less postoperative pain. The procedure can be safely performed with a good experience in both pancreatic and laparoscopic surgery. 相似文献
10.
PL Pirie BL Rooney TF Pechacek HA Lando LA Schmid 《Canadian Metallurgical Quarterly》1997,22(1):131-137
Exposure to foreign particles sometimes causes inflammatory reactions through production of cytokines and chemoattractants by phagocytic cells. In this study, we focused on macrophage migration inhibitory factor (MIF) to evaluate its pathophysiological role in the phagocytic process. Immunohistochemical analysis of human pseudosynovial tissues retrieved at revision of total hip arthroplasty showed that infiltrating mononuclear and multinuclear cells were positively stained by both an anti-CD68 antibody and anti-human MIF antibody. For in vitro study, MIF was released from murine macrophage-like cells (RAW 264.7) in response to phagocytosis of fluorescent-latex beads in a particle dose-dependent manner. Northern blot analysis showed marked elevation of the MIF mRNA level in the phagocytic macrophage-like cells. Moreover, pretreatment of RAW 264.7 cells with rat recombinant MIF increased the extent of phagocytosis by 1.6-fold compared with the control. Taken together, these results suggest that MIF plays an important role by activating macrophages in autocrine and paracrine fashion to phagocytose foreign particles. 相似文献