全文获取类型
收费全文 | 152511篇 |
免费 | 5355篇 |
国内免费 | 6437篇 |
出版年
2024年 | 145篇 |
2023年 | 738篇 |
2022年 | 1714篇 |
2021年 | 2946篇 |
2020年 | 2056篇 |
2019年 | 2616篇 |
2018年 | 14015篇 |
2017年 | 12398篇 |
2016年 | 9924篇 |
2015年 | 4033篇 |
2014年 | 4570篇 |
2013年 | 4900篇 |
2012年 | 9446篇 |
2011年 | 17418篇 |
2010年 | 15207篇 |
2009年 | 11128篇 |
2008年 | 13175篇 |
2007年 | 14336篇 |
2006年 | 3056篇 |
2005年 | 2795篇 |
2004年 | 3055篇 |
2003年 | 2979篇 |
2002年 | 2403篇 |
2001年 | 1457篇 |
2000年 | 1175篇 |
1999年 | 794篇 |
1998年 | 525篇 |
1997年 | 424篇 |
1996年 | 395篇 |
1995年 | 374篇 |
1994年 | 367篇 |
1993年 | 293篇 |
1992年 | 352篇 |
1991年 | 321篇 |
1990年 | 235篇 |
1989年 | 215篇 |
1988年 | 154篇 |
1987年 | 212篇 |
1986年 | 155篇 |
1985年 | 138篇 |
1984年 | 116篇 |
1983年 | 121篇 |
1982年 | 90篇 |
1981年 | 85篇 |
1979年 | 67篇 |
1978年 | 67篇 |
1976年 | 54篇 |
1973年 | 66篇 |
1972年 | 302篇 |
1971年 | 308篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
121.
122.
123.
Se-Chan Kim Alexander Ghanem Heidi Stapel Klaus Tiemann Pascal Knuefermann Andreas Hoeft Rainer Meyer Christian Grohé Anne A Knowlton Georg Baumgarten 《BMC physiology》2007,7(1):5
Backgound
It has been reported that Toll-like receptor 4 (TLR4) deficiency reduces infarct size after myocardial ischemia/reperfusion (MI/R). However, measurement of MI/R injury was limited and did not include cardiac function. In a chronic closed-chest model we assessed whether cardiac function is preserved in TLR4-deficient mice (C3H/HeJ) following MI/R, and whether myocardial and systemic cytokine expression differed compared to wild type (WT). 相似文献124.
125.
126.
127.
M. I. Ibragimova A. I. Chushnikov G. V. Cherepnev V. Yu. Petukhov E. P. Zheglov 《Biophysics》2014,59(3):425-430
The iron metabolism was studied in serum blood samples collected from 26 professional sportsmen undergoing intensive physical exercises using EPR combined with hematological and biochemical laboratory tests. Only 23% of EPR spectra (n = 6) were practically normal while in the rest spectra additional abnormal absorption lines were detected. Presumably, the significant portion of new signals may be caused by different cytochromes. Moreover, the anisotropic signals with g 1 ? 2.02; g 2 ? 1.94 and g 3 ? 1.86 registered in some spectra pointed to the sulfur-iron centers. There was nearly linear correlation between the concentration of Fe3+ in transferrin (Fe3+-Tf) obtained from the EPR spectra and the serum iron concentration measured by absorption photometry both for sportsmen and controls (healthy individuals and patients with different diseases). At equal serum iron concentrations the Fe3+-Tf level was higher in sportsmen than that in controls. The Pearson correlation coefficient (r) for Fe3+-Tf and serum iron values was equal to 0.89 in sportsmen versus r = 0.97 in controls. Additional new lines in serum EPR spectra of professional sportsmen prove the suitability of EPR assay for scheduled medical exams since routine biochemical and hematological tests are insufficient to discover all abnormalities in iron metabolism under intensive physical exercises. 相似文献
128.
129.
Craig B. H. Surman David W. Goodman 《Attention deficit and hyperactivity disorders》2017,9(3):161-168
ADHD is a neurodevelopmental syndrome that often persists into adulthood. It is possible that different criteria are necessary for older adults than younger adults: the manifestations of ADHD could change with age; other conditions with onset in later life share presenting symptoms with ADHD; different contextual challenges and patterns of compensatory support may exist. For these reasons, we reviewed evidence for the validity of DSM ADHD criteria in adulthood for individuals over the age of 50. Specifically, we evaluated evidence that the DSM criteria for ADHD identify a valid syndrome in older adults based on clinical presentation, laboratory or testing findings, absence of alternate diagnosis to explain symptoms, course of the syndrome, or familial presence of the condition. We found evidence that various ADHD criteria identify subjects with clinical presentations similar to that seen in younger adults, but only 92 well-described cases have been reported in the literature. ADHD traits also may be less common in the general population of older adults than in younger adults, suggesting that the threshold for an atypical burden of ADHD traits may be lower in older populations. Future research can establish a richer basis for validity of diagnostic criteria for ADHD in older adults. 相似文献
130.
Olga Maslova Oleg Fedevych Nadiia Shuvalova Olena Deryabina Volodymyr Zhovnir Miroslav Novak Peter Kruzliak 《Cell and tissue banking》2016,17(2):335-339
The need for selection of the optimal material for the manufacturing of cardio-patches can be resolved by the use of cryostored autologous pericardial tissue. This short communication is a concise fragment of a large-scale research and demonstrates only the efficiency of cell culturing before and after pericardial preservation in the low temperature conditions. 相似文献