首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2671篇
  免费   122篇
  2021年   14篇
  2020年   15篇
  2019年   27篇
  2018年   30篇
  2017年   26篇
  2016年   42篇
  2015年   64篇
  2014年   68篇
  2013年   256篇
  2012年   173篇
  2011年   166篇
  2010年   85篇
  2009年   117篇
  2008年   162篇
  2007年   145篇
  2006年   151篇
  2005年   149篇
  2004年   163篇
  2003年   158篇
  2002年   143篇
  2001年   32篇
  2000年   35篇
  1999年   48篇
  1998年   34篇
  1997年   34篇
  1996年   28篇
  1995年   35篇
  1994年   31篇
  1993年   28篇
  1992年   36篇
  1991年   20篇
  1990年   11篇
  1989年   17篇
  1988年   16篇
  1987年   14篇
  1986年   13篇
  1985年   15篇
  1984年   16篇
  1983年   8篇
  1982年   10篇
  1981年   23篇
  1980年   13篇
  1979年   12篇
  1978年   8篇
  1977年   13篇
  1976年   10篇
  1975年   7篇
  1974年   7篇
  1973年   13篇
  1971年   7篇
排序方式: 共有2793条查询结果,搜索用时 578 毫秒
141.
142.
Primary neuroendocrine neoplasm of the liver is extremely rare in both humans and non‐human primates. The present report describes the clinical and pathological findings of an aged Japanese macaque (Macaca fuscata) with hepatic neuroendocrine carcinoma. To our knowledge, this is the first report of hepatic neuroendocrine neoplasm in macaques.  相似文献   
143.
Progress in metabolomic analysis now allows the evaluation of food quality. This study aims to identify the metabolites in meat from livestock using a metabolomic approach. Using gas chromatography–mass spectrometry (GC/MS), many metabolites were reproducibly detected in meats, and distinct differences between livestock species (cattle, pigs, and chickens) were indicated. A comparison of metabolites between tissues types (muscle, intramuscular fat, and intermuscular fat) in marbled beef of Japanese Black cattle revealed that most metabolites are abundant in the muscle tissue. Several metabolites (medium-chain fatty acids, etc.) involved in triacylglycerol synthesis were uniquely detected in fat tissue. Additionally, the results of multivariate analysis suggest that GC/MS analysis of metabolites can distinguish between cattle breeds. These results provide useful information for the analysis of meat quality using GC/MS-based metabolomic analysis.

ABBREVIATIONS: GC/MS: gas chromatography-mass spectrometry; NMR: nuclear magnetic resonance; MS: mass spectrometry; IS: 2-isopropylmalic acid; MSTFA: N-Methyl-N-trimethylsilyltrifluoroacetamide; CV: coefficient of variation; TBS: Tris-buffered saline; MHC: myosin fast type; PCA: principal component analysis; OPLS-DA: orthogonal partial least-squares discriminant analysis; O2PLS: two-way orthogonal partial least-squares  相似文献   

144.
Minoru Otokawa 《BBA》1972,275(3):464-466
Microtubule protein and 30-S dynein (an axonemal ATPase protein) were prepared from cilia of Tetrahymena pyriformis and their mutual interaction was investigated. Microtubular protein stimulated the ATPase activity of 30-S dynein. These observations give some support to models involving the interaction between tubules and dynein arms in ciliary movement.  相似文献   
145.
146.
147.
The cell cycle inhibitor p21 plays an important role in monocytic cell differentiation, during which it translocates from the nucleus to cytoplasm. This process involves the negative regulation of the p21 nuclear localization signal (NLS). Here, we sought to determine the relationship between the cytoplasmic translocation of p21 and another molecule, Brap2, a cytoplasmic protein which binds the NLS of BRCA1 and was recently reported to inactivate KSR in the Ras-activating signal pathway under the name of IMP. We report that p21 and Brap2 directly interact, both in vitro and in vivo, in a manner requiring the NLS of p21 and the C-terminal portion of Brap2. When it is cotransfected with Brap2, p21 is expressed in the cytoplasm. Monocytic differentiation of the promyelomonocytic cell lines U937 and HL60 is associated with the upregulation of Brap2 expression concomitantly with the upregulation and cytoplasmic relocalization of p21. Our results underscore the role played by Brap2 in the process of cytoplasmic translocation of p21 during monocyte differentiation.  相似文献   
148.
A new bacterial strain capable of producing cellulose was isolated from a hot spring. The isolate was Gram-negative, aerobic, and rod-shaped. The optimum temperature for growth was 40-45 degrees C. Methanol, glucose and other common carbohydrates were not utilized as sole growth substrates. Thiosulfate was not oxidized. The G+C content of the DNA was determined to be 64.0 mol%. Comparative 16S rDNA analysis indicated that Bosea thiooxidans and some strains of the genus Methylobacterium were the nearest relatives. The isolate can be distinguished from these relatives by its defectiveness in methanol utilization and thiosulfate oxidation. On the basis of its phenotypic properties and phylogeny, it is proposed that the isolate be designated Balneomonas flocculans gen. nov., sp. nov. The type strain is TFBT (= JCM 11936T, = KCTC 12101T, = IAM 15034T, = ATCC BAA-817T).  相似文献   
149.
150.
Ohtsuka M  Kikuchi N  Ozato K  Inoko H  Kimura M 《Genomics》2004,83(6):1063-1071
Medaka is one of the prominent model animals, which also include other fishes such as Fugu and zebrafish. Its genome is relatively compact but has not been well characterized. Here we have sequenced a 229-kb region of medaka, containing the Double anal fin (Da) locus, and compared its structure to those in Fugu, human, and mouse. This region, representing a gene-poor region, contains no major rearrangements and can be readily compared among different species. Comparison of G+C contents and repeats suggested that medaka and Fugu are highly related as expected and that medaka is more similar to mammals than Fugu is. Sequence comparisons of developmental genes zic1 and zic4, identified within this region, revealed that zic1, but not zic4, is highly conserved among vertebrates. The 5' coding region of zic4 is, however, extremely homologous among fishes with little synonymous substitutions, implying its distinct function in fish.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号