全文获取类型
收费全文 | 132100篇 |
免费 | 4605篇 |
国内免费 | 823篇 |
专业分类
137528篇 |
出版年
2022年 | 303篇 |
2021年 | 522篇 |
2020年 | 346篇 |
2019年 | 423篇 |
2018年 | 12224篇 |
2017年 | 11035篇 |
2016年 | 8236篇 |
2015年 | 2187篇 |
2014年 | 1827篇 |
2013年 | 2363篇 |
2012年 | 6499篇 |
2011年 | 14747篇 |
2010年 | 13256篇 |
2009年 | 9436篇 |
2008年 | 11431篇 |
2007年 | 12973篇 |
2006年 | 1848篇 |
2005年 | 2056篇 |
2004年 | 2416篇 |
2003年 | 2266篇 |
2002年 | 2025篇 |
2001年 | 1475篇 |
2000年 | 1391篇 |
1999年 | 1128篇 |
1998年 | 614篇 |
1997年 | 585篇 |
1996年 | 560篇 |
1995年 | 536篇 |
1994年 | 495篇 |
1993年 | 541篇 |
1992年 | 1023篇 |
1991年 | 785篇 |
1990年 | 777篇 |
1989年 | 760篇 |
1988年 | 669篇 |
1987年 | 610篇 |
1986年 | 609篇 |
1985年 | 707篇 |
1984年 | 538篇 |
1983年 | 429篇 |
1982年 | 342篇 |
1981年 | 312篇 |
1980年 | 254篇 |
1979年 | 379篇 |
1978年 | 343篇 |
1977年 | 241篇 |
1974年 | 289篇 |
1973年 | 250篇 |
1972年 | 436篇 |
1971年 | 416篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
111.
112.
A comparison of the respiratory chain in particles from Paracoccus denitrificans and bovine heart mitochondria by EPR spectroscopy 总被引:6,自引:0,他引:6
S P Albracht H W van Verseveld W R Hagen M L Kalkman 《Biochimica et biophysica acta》1980,593(2):173-186
A study is presented on the EPR characteristics of the paramagnetic groups in the respiratory chain present in membrane particles of Paracoccus denitrificans, the respiratory system of which is very similar to that in submitochondrial particles from beef heart. All paramagnetic prosthetic groups of the mitochondrial system are also found in the bacterial plasma membrane. Their properties suggest that the respiratory groups are embedded in very similar protein environments in the two systems. 相似文献
113.
114.
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115.
116.
117.
118.
119.
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
120.
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