全文获取类型
收费全文 | 1412篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 26篇 |
金属工艺 | 1篇 |
机械仪表 | 8篇 |
建筑科学 | 5篇 |
能源动力 | 5篇 |
轻工业 | 41篇 |
水利工程 | 1篇 |
无线电 | 10篇 |
一般工业技术 | 84篇 |
冶金工业 | 1196篇 |
原子能技术 | 2篇 |
自动化技术 | 32篇 |
出版年
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2016年 | 2篇 |
2013年 | 27篇 |
2012年 | 12篇 |
2011年 | 13篇 |
2010年 | 9篇 |
2009年 | 9篇 |
2008年 | 11篇 |
2007年 | 14篇 |
2006年 | 11篇 |
2005年 | 9篇 |
2004年 | 9篇 |
2003年 | 13篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 35篇 |
1998年 | 388篇 |
1997年 | 200篇 |
1996年 | 134篇 |
1995年 | 84篇 |
1994年 | 70篇 |
1993年 | 70篇 |
1992年 | 6篇 |
1991年 | 14篇 |
1990年 | 17篇 |
1989年 | 18篇 |
1988年 | 19篇 |
1987年 | 4篇 |
1986年 | 23篇 |
1985年 | 10篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 13篇 |
1978年 | 6篇 |
1977年 | 23篇 |
1976年 | 78篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1965年 | 1篇 |
1960年 | 1篇 |
1955年 | 1篇 |
1944年 | 1篇 |
1942年 | 1篇 |
1921年 | 1篇 |
1907年 | 1篇 |
排序方式: 共有1414条查询结果,搜索用时 31 毫秒
1.
2.
3.
We have studied the function of partial orthotopic liver transplantation in the rat by evaluating prothrombin time (PT), liver blood flow, basal and glucose-stimulated insulin secretion and glucose tolerance, and the reticuloendothelial function (RES) in hepatectomized rats subjected to partial liver transplantation. A graft corresponding to 68% of a normal liver was transplanted to totally hepatectomized rats. Comparison was made between control rats and rats subjected to 32% liver resection. PT was not significantly different in the transplanted group compared with liver-resected and control rats. Laser Doppler flowmetry showed that at 28 days after surgery, blood flow had increased in the transplanted livers. Furthermore, on the third day after transplantation, basal plasma insulin was increased and the plasma insulin response to glucose was exaggerated, suggesting reduced insulin action and impaired insulin degradation. Finally, uptake of radioactive-labeled E. coli bacteria, as a measure of RES function, was not compromised in transplanted animals. Based on these results, we conclude that reduced-size liver transplant in out-bred rats results in fast normalization of liver function after surgery although, immediately after surgery, glucose intolerance is seen. 相似文献
4.
OBJECTIVE: To examine the association between sexual abuse in childhood and adult depression in women. DESIGN: Two stage, case detection and case identification design, using the 30-item general health questionnaire and the Beck depression inventory for screening and the affective items relating to current functioning on the schizophrenia and affective disorders schedule to identify depressed cases. Details of sexual abuse in childhood were elicited retrospectively by semistructured interview, and social problems by the social problems questionnaire. SETTING: Three general practices, in middle class suburban, deprived inner city, and rural areas. SUBJECTS: 1189 women were screened and 237 subsequently interviewed; 132 were depressed. RESULTS: 49 (37%) of the depressed interviews and 24 (23%) of the non-depressed interviews reported experience of sexual abuse when they were aged under 16 years. A positive association existed between the more severe abuse and depression--all those who had experienced penetration were depressed as adults. A relation was also found between sexual abuse in childhood and sexual problems, housing problems, and problems with their children at school. CONCLUSION: A positive association between child sexual abuse and depression was confirmed, but this was confined to more severe abuse (penetration or attempted penetration). 相似文献
5.
The implementation of Medicare's prospective payment system in acute care has coincided with a steady increase in medically unstable admissions to our freestanding rehabilitation facility. We investigated the consequences of these admissions by collecting medical information regarding transfers beginning in 1983. Patients requiring transfer back to the acute setting within 1 day of admission were considered medically unstable and their charts were reviewed. The number of patients requiring transfer back within 1 day increased from 1.5% of all first admissions to 3.1% in 1988 (Mantel - Haenszel chi 2 = 8.03, (df = 1), p < .01), but the increase among Medicare patients alone was not significant. This progressive increase was most pronounced in the cerebrovascular accident and spinal cord injury populations. Beginning in 1988, an intensified preadmission evaluation program was implemented, resulting in a significant decline in unstable patient transfers from hospitals where our consultants were on staff. Physiatric consultations at referral institutions decreased the number of unstable patients at admission. 相似文献
6.
The purpose of this study was to identify family physicians' firearm safety counseling beliefs and behaviors. A survey was mailed to a random sample of 600 members of the American Academy of Family Physicians. A three wave mailing technique was used to maximize the response rate and yielded 271 usable surveys (55% response rate). Outcome measures included training experience in firearm safety counseling, the prevalence of firearm safety counseling by family physicians, and their perceptions regarding such counseling. The majority (78%) of family physicians lacked formal training on how to counsel patients about firearm safety and 49% believed more time should be spent in residency programs on firearm safety counseling. The majority (84%) of respondents never or rarely counseled patients on firearm safety and 50% believed firearm safety counseling should be a low priority in their delivery of primary care. The majority of respondents did not regularly counsel patients about firearm safety, did not believe firearm safety counseling should be a priority, and did not believe firearm safety counseling would be effective in reducing firearm-related trauma. 相似文献
7.
S Knecht M Deppe EB Ringelstein M Wirtz H Lohmann B Dr?ger T Huber H Henningsen 《Canadian Metallurgical Quarterly》1998,29(6):1155-1159
BACKGROUND AND PURPOSE: Since functional transcranial Doppler ultrasonography (fTCD) allows convenient and fully automated quantification of language lateralization, it seems ideal for longitudinal studies of perfusion changes during deterioration as well as recovery of language functions. However, during serial examinations, the technical, stochastic, and physiological variabilities of cerebral blood flow velocities (CBFV) have to be considered. Therefore, before fTCD is accepted as a tool for evaluation of changes in lateralization in the diseased state, its reliability in healthy subjects needs to be determined. METHODS: We performed fTCD during a word generation task based on a previously validated technique with automated calculation of the averaged CBFV differences in the middle cerebral arteries providing an index of lateralization (LI). RESULTS: (1) The accuracy of the LI as assessed by the confidence interval was better than 1% of the mean hemispheric difference. (2) On repeated examination, LIs obtained from 10 subjects showed a high test-retest reproducibility (Pearson product moment correlation coefficient r = 0.95, P < 0.0001). (3) On 10 repeated assessments of LI in the same subject, no practice effects were detected. CONCLUSIONS: Functional TCD is a suitable and very robust tool for the longitudinal quantitative measurement of cerebral language lateralization. 相似文献
8.
9.
10.