全文获取类型
收费全文 | 901篇 |
免费 | 4篇 |
国内免费 | 2篇 |
专业分类
化学工业 | 5篇 |
金属工艺 | 4篇 |
水利工程 | 1篇 |
无线电 | 3篇 |
一般工业技术 | 3篇 |
冶金工业 | 891篇 |
出版年
2017年 | 1篇 |
2015年 | 1篇 |
2014年 | 4篇 |
2012年 | 1篇 |
2009年 | 2篇 |
2007年 | 2篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2000年 | 1篇 |
1999年 | 27篇 |
1998年 | 282篇 |
1997年 | 161篇 |
1996年 | 109篇 |
1995年 | 71篇 |
1994年 | 45篇 |
1993年 | 53篇 |
1992年 | 8篇 |
1991年 | 13篇 |
1990年 | 10篇 |
1989年 | 14篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 14篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 8篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 18篇 |
1976年 | 20篇 |
1975年 | 2篇 |
排序方式: 共有907条查询结果,搜索用时 15 毫秒
61.
Adenocarcinoma of the gallbladder combined with a malignant peripheral nerve sheath tumor (MPNST) in the gallbladder in an 81-year-old woman is reported. The resected gallbladder showed two distinct tumor components, the epithelioid type of MPNST and adenocarcinoma with areas of mucin production. Although the immediate postoperative course was uneventful, a pathologic fracture of her right upper femur developed 4 months after the cholecystectomy. The pathology was determined to be a feature of metastatic MPNST rather than of adenocarcinoma. A whole body bone scan revealed multiple metastases, including the left parietal skull, left ninth rib, seventh thoracic vertebra, and right upper third of the femur. Despite cholecystectomy and postoperative irradiation therapy, she died 6 months after diagnosis of the tumor. Without an autopsy the primary site of the MPNST was unknown. We found that the prognosis was very poor in patients with distal metastatic MPNST, especially in older patients. 相似文献
62.
63.
JR Hebert TG Hurley BC Olendzki J Teas Y Ma JS Hampl 《Canadian Metallurgical Quarterly》1998,90(21):1637-1647
BACKGROUND: Large international variations in rates of prostate cancer incidence and mortality suggest that environmental factors have a strong influence on the development of this disease. The purpose of this study was to identify predictive variables for prostate cancer mortality in data from 59 countries. METHODS: Data on prostate cancer mortality, food consumption, tobacco use, socioeconomic factors, reproductive factors, and health indicators were obtained from United Nations sources. Linear regression models were fit to these data. The influence of each variable fit in the regression models was assessed by multiplying the regression coefficient b by the 75th (X75) and 25th (X25) percentile values of the variable. The difference, bX75 - bX25, is the estimated effect of the variable across its interquartile range on mortality rates measured as deaths per 100000 males aged 45-74 years. Reported P values are two-sided. RESULTS: Prostate cancer mortality was inversely associated with estimated consumption of cereals (bX75 - bX25 = -7.31 deaths; P = .001), nuts and oilseeds (bX75 - bX25 = -1.72 deaths; P = .003), and fish (bX75 - bX25 = -1.47 deaths; P = .001). In the 42 countries for which we had appropriate data, soy products were found to be significantly protective (P = .0001), with an effect size per kilocalorie at least four times as large as that of any other dietary factor. Besides variables related to diet, we observed an association between prostate cancer mortality rates and a composite of other health-related, sanitation, and economic variables (P = .003). CONCLUSIONS: The specific food-related results from this study are consistent with previous information and support the current dietary guidelines and hypothesis that grains, cereals, and nuts are protective against prostate cancer. The findings also provide a rationale for future study of soy products in prostate cancer prevention trials. 相似文献
64.
Depletion of a Drosophila homolog of yeast Sup35p disrupts spindle assembly, chromosome segregation, and cytokinesis during male meiosis 总被引:1,自引:0,他引:1
J Basu BC Williams Z Li EV Williams ML Goldberg 《Canadian Metallurgical Quarterly》1998,39(4):286-302
This paper addresses the effects of availability and anchoring-and-adjustment on people's beliefs and values concerning environmental issues. The first three studies focus on lay people's perceptions of the causes of large scale environmental risks, the second series of three studies deals with how people value environmental goods and how much they are prepared to pay to mitigate environmental risks. In studies 1-3 we investigate the effects of availability and anchoring-and-adjustment on estimating the contribution of various factors to large scale environmental risks. Highly complex risks such as acid rain and global warming tend to be associated with multiple causes, and our results show that estimating the role of these causes is clearly affected by availability and anchoring-and-adjustment. Both have sizeable effects and persist over time. Moreover, corrective procedures only seem to have a limited effect. Availability and anchoring-and-adjustment not only play a role in judging the possible causes of risks; they also play a role in research attempting to assess the public's willingness to pay (WTP) to protect our environment. The outcomes of WTP surveys are often used as a tool to help policy decision making. In the second part of this article we present three studies on this issue. Results provide further evidence of the impact of the two heuristics on the outcomes of WTP research. Implications for research and practice are briefly discussed. 相似文献
65.
S Freudenberg D Lorenz BC Manegold M Woenckhaus 《Canadian Metallurgical Quarterly》1998,69(7):780-782
We report the case of a 34-year-old woman with severe rectal bleeding since the age of 17. The cause of the bleeding was a cavernous haemangioma of the rectum. The extent of the disease was not realised for many years. Sclerosing injections, laser coagulation and even suture ligation were helpful in acute bleeding episodes but did not result in definitive healing. Finally cure was achieved by resection of the rectum and colo-anal sleeve anastomosis. The clinical presentation and the management are described and discussed. 相似文献
66.
AIM: To study pharmacokinetics of tablet huperzine A (Hup-A) in Chinese volunteers to help establishing its drug administration schedule. METHODS: For 6 volunteers after a single oral dose of 0.99 mg, drug concentrations in plasma were assayed by reverse phase high pressure liquid chromatography (HPLC) at 0.5, 0.75, 1.0, 1.25, 1.5, 2, 4, 6, 8, and 10 h. The pharmacokinetic parameters were calculated with a 3P87 program by computer. RESULTS: The time course of plasma concentrations conformed to a one-compartment open model with a first order absorption. The pharmacokinetic parameters were as follows: T 1/2ka = 12.6 min, T 1/2ke = 288.5 min, Tmax = 79.6 min, Cmax = 8.4 micrograms L-1, AUC = 4.1 mg L-1 min. CONCLUSION: Hup-A was absorbed rapidly, distributed widely in the body, and eliminated at a moderate rate. 相似文献
67.
Hope is the sum of goal thoughts as tapped by pathways and agency. Pathways reflect the perceived capability to produce goal routes; agency reflects the perception that one can initiate action along these pathways. Using trait and state hope scales, studies explored hope in college student athletes. In Study 1, male and female athletes were higher in trait hope than nonathletes; moreover, hope significantly predicted semester grade averages beyond cumulative grade point average and overall self-worth. In Study 2, with female cross-country athletes, trait hope predicted athletic outcomes; further, weekly state hope tended to predict athletic outcomes beyond dispositional hope, training, and self-esteem, confidence, and mood. In Study 3, with female track athletes, dispositional hope significantly predicted athletic outcomes beyond variance related to athletic abilities and affectivity; moreover, athletes had higher hope than nonathletes. 相似文献
68.
69.
Hypothalamic GABAergic activity and immune response in spleen were not significantly changed with the increase of age from 3 to 6 months in adult male albino rats. Further increase of age from 6 to 9 months increase the GABAergic activity and decreased the cell viability in spleen without any change in its T-lymphocyte cytotoxicity. Consumption of low protein diet (LPD) for a short-term period (STP; 7 consecutive days) increased the hypothalamic GABAergic activity without changing the immune response in 3 months old rats. When supplemented for a long-term period (LTP; 30 consecutive days) to 3 months old rats, a reduction of hypothalamic GABAergic activity and the immune response was observed. Intake of high protein diet (HPD) for both STP and LTP increased the GABAergic activity and immune response, but the increase of GABAergic activity in hypothalamus under STP was greater than that observed under LTP. In 6 months old rats consumption of LPD for STP reduced the GABAergic activity without any alteration of its immune response. Long-term supplementation of this LPD to the same age group increased GABAergic activity and the mitotic activity of spleen cells without any alteration of the functional activity of the T-cells in spleen. Consumption of HPD for STP failed to produce any change in hypothalamic GABAergic activity and the immune response of 6 months old rats. Supplementation of HPD for LTP reduced the hypothalamic GABAergic activity and the immune response of the same age group. The reduction in hypothalamic GABAergic activity without any change in the immune response was observed following the supplementation of low protein diet to 9 months old rat for STP. Intake of the LPD for LTP also reduced the hypothalamic GABAergic activity and the mitotic activity of the spleen cells without any alteration of the functional activity of the T-cells in spleen of 9 months old rats. Supplementation of HPD for STP to this aged rat, on the other hand, failed to produced any change in hypothalamic GABAergic activity and the immune response. Intake of HPD for LTP by this aged rats increased the hypothalamic GABAergic activity along with the immune response. The results of this study, thus, suggest that hypothalamic GABAergic activity during aging is an index of immune response and it is modulated following the short- and long-term consumption of protein poor and protein rich diet. 相似文献
70.