全文获取类型
收费全文 | 8784篇 |
免费 | 191篇 |
国内免费 | 28篇 |
学科分类
工业技术 | 9003篇 |
出版年
2023年 | 67篇 |
2022年 | 142篇 |
2021年 | 172篇 |
2020年 | 151篇 |
2019年 | 143篇 |
2018年 | 226篇 |
2017年 | 186篇 |
2016年 | 192篇 |
2015年 | 104篇 |
2014年 | 202篇 |
2013年 | 403篇 |
2012年 | 222篇 |
2011年 | 305篇 |
2010年 | 231篇 |
2009年 | 275篇 |
2008年 | 245篇 |
2007年 | 200篇 |
2006年 | 213篇 |
2005年 | 157篇 |
2004年 | 131篇 |
2003年 | 135篇 |
2002年 | 131篇 |
2001年 | 127篇 |
2000年 | 129篇 |
1999年 | 159篇 |
1998年 | 828篇 |
1997年 | 484篇 |
1996年 | 367篇 |
1995年 | 272篇 |
1994年 | 205篇 |
1993年 | 237篇 |
1992年 | 126篇 |
1991年 | 136篇 |
1990年 | 118篇 |
1989年 | 93篇 |
1988年 | 98篇 |
1987年 | 106篇 |
1986年 | 115篇 |
1985年 | 140篇 |
1984年 | 99篇 |
1983年 | 95篇 |
1982年 | 82篇 |
1981年 | 70篇 |
1980年 | 58篇 |
1979年 | 46篇 |
1978年 | 53篇 |
1977年 | 87篇 |
1976年 | 184篇 |
1975年 | 48篇 |
1973年 | 42篇 |
排序方式: 共有9003条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
Digant Gupta Christopher G Lis Sadie L Dahlk Jessica King Pankaj G Vashi James F Grutsch Carolyn A Lammersfeld 《Nutrition journal》2008,7(1):19
Background
Bioelectrical Impedance (BIA) derived phase angle is increasingly being used as an objective indicator of nutritional status in advanced cancer. Subjective Global Assessment (SGA) is a subjective method of nutritional status. The objective of this study was to investigate the association between BIA derived phase angle and SGA in advanced colorectal cancer. 相似文献7.
Lussier Isabelle; Derevensky Jeffrey L.; Gupta Rina; Bergevin Tanya; Ellenbogen Stephen 《Canadian Metallurgical Quarterly》2007,21(2):165
The study of resilient children has overturned many deficit-focused models concerning the ontogenesis of children raised in adversity. This study explored the relationship between risk and protective factors, resilience, and youth gambling behavior. More specifically, this study examined the relative contribution of various risk and protective domains in relation to problem gambling behavior and examined whether youth identified as resilient (high risk exposure- high internalized protection) were as likely as those identified as vulnerable (high risk exposure-low internalized protection) to engage in excessive gambling behavior. The sample consisted of 1,273 students ages 12 to 19. The findings demonstrated that risk and protective factors each provide a unique contribution to the prediction model of gambling problems. Resilient and vulnerable youth differed significantly in their self-reported gambling severity. As well, resilient youth were not statistically distinguishable from low-risk exposure groups in terms of their gambling severity. Findings are interpreted with respect to resilience and prevention research. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
Sudhir Singh Bhadauria Dr. Mahesh Chandra Gupta 《Canadian Metallurgical Quarterly》2007,21(3):234-239
Reports of failure of existing concrete structures due to a lack of durability, rather than a deficiency in structural strength, has made concrete technologists, engineers, and researchers focus research on the parameters influencing durability performance with respect to time. Systematic performance monitoring, with respect to chosen durability parameters of existing concrete structures, will decide the direction of future research in this area. Inferences based on laboratory simulations and testing need to be confirmed by in situ field measurements and studies. In situ condition rating and performance monitoring surveys have been conducted by many researchers, scientists, and professional associations, and reported in literature. Inferences of few such studies are summarized and discussed. Deterioration of concrete structures constructed in recent times is observed at relatively faster rates, and has been mainly attributed to cracking. Cracking is associated with the use of faster-hydrating portland cements with increased fineness and the tricalcium silicate (C3S) content to support the high speed of modern construction. In the present research, a case study of deteriorated water tank structures situated in the semitropical region of India is presented. Some selected parameters—such as concrete cover, carbonation depth, chloride concentration, compressive strength, etc. which influence long term durability of structures—have been measured. 相似文献
9.
A 78-year-old Chinese woman presented with recurrent postprandial abdominal pain. Computerised tomography revealed a small bowel tumour causing volvulus of a segment of the small bowel. Laparotomy confirmed an extraluminal ileal tumour with partial volvulus of the involved small bowel segment. Small bowel resection was done. Histological and ultrastructural studies confirmed a gastrointestinal autonomic nerve tumour. We review the medical literature on this rare tumour. 相似文献
10.
BD Shenstone A Mahmoud R Woodward D Elvins R Palmer EF Ring AK Bhalla 《Canadian Metallurgical Quarterly》1994,33(6):541-545
A prospective longitudinal study of patients with early RA was performed to examine the influence of disease duration, disease activity and physical activity on bone loss. Sixty-seven patients with non-steroid treated RA of less than 5 yr duration, including 16 patients with disease duration less than 6 months, had BMD measurements of the femoral neck and the lumbar spine over a 12-month period using dual energy X-ray absorptiometry. The BMD changes were compared with values from 72 control patients and were also correlated with serial measurements of disease activity (measured by the Stoke Index) and disability [measured by the Health Assessment Questionnaire (HAQ) score], at 3-monthly intervals over the 12-month period. No significant differences in BMD changes were found between RA patients and controls overall. Patients with disease duration of less than 6 months had significantly greater loss of BMD at the femoral neck (-3.9%, S.E.M. 1.5) than the remainder of the cohort (-0.2%, S.E.M. 0.7) (P = 0.02) and controls (-0.8%, S.E.M. 0.6). Lumbar spine BMD changes correlated with the initial Stoke Index (Rs-0.373, P = 0.01) but not mean Stoke Indices. There was no correlation of BMD changes with age or HAQ scores. These findings suggest that significant bone loss occurs within the first few months of disease in patients with RA. 相似文献