全文获取类型
收费全文 | 114359篇 |
免费 | 12073篇 |
国内免费 | 33274篇 |
出版年
2024年 | 287篇 |
2023年 | 2269篇 |
2022年 | 3580篇 |
2021年 | 5858篇 |
2020年 | 4910篇 |
2019年 | 5868篇 |
2018年 | 4846篇 |
2017年 | 4311篇 |
2016年 | 5082篇 |
2015年 | 6533篇 |
2014年 | 8711篇 |
2013年 | 8532篇 |
2012年 | 10784篇 |
2011年 | 10375篇 |
2010年 | 7910篇 |
2009年 | 7560篇 |
2008年 | 8465篇 |
2007年 | 7837篇 |
2006年 | 7282篇 |
2005年 | 6073篇 |
2004年 | 5148篇 |
2003年 | 4565篇 |
2002年 | 4032篇 |
2001年 | 3505篇 |
2000年 | 3121篇 |
1999年 | 2181篇 |
1998年 | 1255篇 |
1997年 | 914篇 |
1996年 | 819篇 |
1995年 | 706篇 |
1994年 | 649篇 |
1993年 | 517篇 |
1992年 | 582篇 |
1991年 | 548篇 |
1990年 | 433篇 |
1989年 | 388篇 |
1988年 | 345篇 |
1987年 | 329篇 |
1986年 | 281篇 |
1985年 | 299篇 |
1984年 | 246篇 |
1983年 | 187篇 |
1982年 | 222篇 |
1981年 | 147篇 |
1980年 | 77篇 |
1979年 | 96篇 |
1978年 | 92篇 |
1977年 | 69篇 |
1973年 | 84篇 |
1972年 | 70篇 |
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
41.
Ai‐Xin Song Chen‐Jie Zhou Xiao Guan Kong‐Hung Sze Hong‐Yu Hu 《Protein science : a publication of the Protein Society》2010,19(5):1104-1109
DC‐UbP/UBTD2 is a ubiquitin (Ub) domain‐containing protein first identified from dendritic cells, and is implicated in ubiquitination pathway. The solution structure and backbone dynamics of the C‐terminal Ub‐like (UbL) domain were elucidated in our previous work. To further understand the biological function of DC‐UbP, we then solved the solution structure of the N‐terminal domain of DC‐UbP (DC‐UbP_N) and studied its Ub binding properties by NMR techniques. The results show that DC‐UbP_N holds a novel structural fold and acts as a Ub‐binding domain (UBD) but with low affinity. This implies that the DC‐UbP protein, composing of a combination of both UbL and UBD domains, might play an important role in regulating protein ubiquitination and delivery of ubiquitinated substrates in eukaryotic cells. 相似文献
42.
43.
O. B. Kazakova E. F. Khusnutdinova G. A. Tolstikov K. Yu. Suponitsky 《Russian Journal of Bioorganic Chemistry》2010,36(4):512-515
New olean-18(19)-ene triterpenoids were effectively synthesized by the interaction of allobetulin or its acetate with phosphorous
oxychloride in refluxing pyridine. The structures of the synthesized 17-chloromethyloleane-18(19)-enes were confirmed by NMR
spectroscopy and X-ray analysis. 相似文献
44.
N-糖蛋白去糖基化酶(PNGase)是一种广泛存在于真菌、植物、哺乳动物中的去糖基化酶,可以水解N-糖蛋白或 N-糖肽上天冬酰胺与寡糖链连接的化学键,并释放出完整的N-寡糖。PNGase在生物体内参与蛋白质降解、器官发育、个体生长等过程。人PNGase基因功能缺陷会导致先天性去糖基化障碍,小鼠PNGase缺陷会导致胚胎致死性,线虫PNGase缺陷使其寿命下降。本文对PNGase在不同物种的分布、蛋白质结构、酶学功能及生物学功能进行阐述,为PNGase的生理病理功能及致病机制的基础研究提供思路,为PNGase作为糖生物学工具酶或药物开发的创新应用研究奠定基础。 相似文献
45.
46.
47.
L. A. Piruzyan V. A. Sukhanov E. V. Kalinina T. Yu. Fedorova A. N. Saprin 《Biology Bulletin》2002,29(2):115-119
We studied intraspecific features of the main enzymes of metabolism and detoxication of xenobiotics on mice (eight inbred lines) and rats (five lines) for estimation of possible variants of complete or incomplete metabolic equality. Significant genetically determined intraspecific differences for activities of the enzymes of metabolism and detoxication of xenobiotics were described. Generalized criteria for comparison of the metabolic status were proposed on the basis of activities of the main enzymes: cytochrome P-450 (hydroxylation and epoxidation), epoxyhydrolase, glutathione-S-transferase, UDP-glucuronosyl transferase, and sulfotransferase. The proposed criteria for estimation of the metabolic parameters of an individual can serve as a basis of metabolic portraiting. 相似文献
48.
49.
Julie A. Harris Akihiko Koyama Sumihiro Maeda Kaitlyn Ho Nino Devidze Dena B. Dubal Gui-Qiu Yu Eliezer Masliah Lennart Mucke 《PloS one》2012,7(9)
Accumulation of hyperphosphorylated tau in the entorhinal cortex (EC) is one of the earliest pathological hallmarks in patients with Alzheimer’s disease (AD). It can occur before significant Aβ deposition and appears to “spread” into anatomically connected brain regions. To determine whether this early-stage pathology is sufficient to cause disease progression and cognitive decline in experimental models, we overexpressed mutant human tau (hTauP301L) predominantly in layer II/III neurons of the mouse EC. Cognitive functions remained normal in mice at 4, 8, 12 and 16 months of age, despite early and extensive tau accumulation in the EC. Perforant path (PP) axon terminals within the dentate gyrus (DG) contained abnormal conformations of tau even in young EC-hTau mice, and phosphorylated tau increased with age in both the EC and PP. In old mice, ultrastructural alterations in presynaptic terminals were observed at PP-to-granule cell synapses. Phosphorylated tau was more abundant in presynaptic than postsynaptic elements. Human and pathological tau was also detected within hippocampal neurons of this mouse model. Thus, hTauP301L accumulation predominantly in the EC and related presynaptic pathology in hippocampal circuits was not sufficient to cause robust cognitive deficits within the age range analyzed here. 相似文献
50.