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   22180篇
  免费   1522篇
  国内免费   982篇
  24684篇
  2024年   53篇
  2023年   295篇
  2022年   631篇
  2021年   1014篇
  2020年   674篇
  2019年   900篇
  2018年   889篇
  2017年   679篇
  2016年   958篇
  2015年   1335篇
  2014年   1511篇
  2013年   1752篇
  2012年   1949篇
  2011年   1819篇
  2010年   1016篇
  2009年   907篇
  2008年   1013篇
  2007年   928篇
  2006年   845篇
  2005年   724篇
  2004年   632篇
  2003年   526篇
  2002年   476篇
  2001年   309篇
  2000年   320篇
  1999年   282篇
  1998年   174篇
  1997年   161篇
  1996年   181篇
  1995年   162篇
  1994年   136篇
  1993年   102篇
  1992年   151篇
  1991年   150篇
  1990年   124篇
  1989年   97篇
  1988年   98篇
  1987年   101篇
  1986年   70篇
  1985年   89篇
  1984年   50篇
  1983年   53篇
  1982年   27篇
  1981年   26篇
  1980年   24篇
  1979年   35篇
  1978年   28篇
  1977年   20篇
  1975年   29篇
  1974年   21篇
排序方式: 共有10000条查询结果,搜索用时 20 毫秒
951.
Copy number variations (CNVs) are important forms of structural variation in human and animals and can be considered as a major genetic component of phenotypic diversity. Here we used the Illumina PorcineSNP60 BeadChip V2 and a DLY [Duroc × (Large White × Landrace)] commercial hybrid population to identify 272 CNVs belonging to 165 CNV regions (CNVRs), of which 66 are new. As CNVRs are specific to origin of population, our DLY-specific data is an important complementary to the existing CNV map in the pig genome. Eight CNVRs were selected for validation by quantitative real-time PCR (qRT-PCR) and the accurate rate was high (87.25%). Gene function analysis suggested that a common CNVR may play an important role in multiple traits, including growth rate and carcass quality.  相似文献   
952.
In recent years, research in life sciences has been remarkably revolutionized owing to the establishment, development and application of genome editing technologies. Genome editing has not only accelerated fundamental research but has also shown promising applications in agricultural breeding and therapy. In particular, the clustered, regularly interspaced, short palindromic repeat (CRISPR) technology has become an indispensable tool in molecular biology owing to its high efficacy and simplicity. Genome editing tools have also been established in silkworm (Bombyx mori), a model organism of Lepidoptera insects with high economic importance. This has remarkably improved the level and scope of silkworm research and could reveal new mechanisms or targets in basic entomology and pest management studies. In this review, we summarize the progress and potential of genome editing in silkworm and its applications in functional genomic studies for generating novel genetic materials.  相似文献   
953.
954.
为筛选胰腺假性囊肿的手术方法,本研究选取胰腺假性囊肿患者73例,观察各患者手术治疗效果。73例患者中,行囊肿十二指肠吻合术者13例(A组),行囊肿胃吻合术者29例(B组),行囊肿空肠吻合术者19例(C组),行胰腺囊肿切除术者12例(D组)。研究发现,各组间术后复发率、吻合口瘘发生率、吻合口出血发生率、住院时间和治疗费用差异不显著(p>0.05);各组术后72 h丙氨酸氨基转移酶(ALT)、天门冬氨酸转氨酶(AST)和尿素氮(BUN)均较术前显著升高(p<0.05);术后72 h,各组间ALT、AST和BUN差异不显著(p>0.05)。研究表明,可根据胰腺假性囊肿具体位置制定合理的手术方案,取得较好的治疗效果,不同手术方式有其适应条件,不应盲目推崇某种手术方式。  相似文献   
955.
956.
Li  Ruixin  Li  ZiXin  Ma  Ke  Wang  Gang  Li  Wei  Liu  Hong-Wei  Yin  Wen-Bing  Zhang  Peng  Liu  Xing-Zhong 《中国科学:生命科学英文版》2019,62(8):1087-1095
Filamentous fungi are excellent sources for the production of a group of bioactive small molecules which are often called secondary metabolites(SMs). The advanced genome sequencing technology combined with bioinformatics analysis reveals a large number of unexplored biosynthetic gene clusters(BGCs) in the fungal genomes. To unlock this fungal SM treasure, many approaches including heterologous expression are being developed and efficient cloning of the BGCs is a crucial step to do this.Here, we present an efficient strategy for the direct cloning of fungal BGCs. This strategy consisted of Splicing by Overlapping Extension(SOE)-PCR and yeast assembly in vivo. By testing 14 BGCs DNA fragments ranging from 7 kb to 52 kb, the average positive rate was over 80%. The maximal insertion size for fungal BGC assembly was 52 kb. Those constructs could be used conveniently for the heterologous expression leading to the discovery of novel natural products. Thus, our results provide an efficient and quick method for the low cost direct cloning of fungal BGCs.  相似文献   
957.
Luo  Lilan  He  Yajun  Zhao  Yannan  Xu  Qian  Wu  Jian  Ma  Haiyan  Guo  Hongyan  Bai  Lin  Zuo  Jianru  Zhou  Jian-Min  Yu  Hong  Li  Jiayang 《中国科学:生命科学英文版》2019,62(8):991-1002
Reactive oxygen species(ROS) play a crucial role in numerous biological processes in plants, including development, responses to environmental stimuli, and programmed cell death(PCD). Deficiency in MOSAIC DEATH 1(MOD1), a plastid-localized enoyl-ACP reductase essential for de novo fatty acid biosynthesis in Arabidopsis thaliana, leads to the increased malate export from chloroplasts to mitochondria, and the subsequent accumulation of mitochondria-generated ROS and PCD. In this study, we report the identification and characterization of a mod1 suppressor, som592. SOM592 encodes mitochondrion-localized NAD~+ transporter 2(NDT2). We show that the mitochondrial NAD pool is elevated in the mod1 mutant. The som592 mutation fully suppressed mitochondrial NADH hyper-accumulation, ROS production, and PCD in the mod1 mutant, indicating a causal relationship between mitochondrial NAD accumulation and ROS/PCD phenotypes. We also show that in wild-type plants, the mitochondrial NAD+uptake is involved in the regulation of ROS production in response to continuous photoperiod. Elevation of the alternative respiration pathway can suppress ROS accumulation and PCD in mod1, but leads to growth restriction. These findings uncover a regulatory mechanism for mitochondrial ROS production via NADH homeostasis in Arabidopsis thaliana that is likely important for growth regulation in response to altered photoperiod.  相似文献   
958.
Danqi soft capsule (DQ) is a traditional Chinese medicine containing Salvia miltiorrhiza and Panax notoginseng; it is safe and efficient in treating ischaemic heart diseases. The purpose of the present study was to assess whether DQ could prevent infarct border zone (IBZ) remodelling and decrease ventricular arrhythmias occurrence in post‐myocardial infarction (MI) stage. MI was induced by a ligation of the left anterior descending coronary artery. DQ was administered to the post‐MI rats started from 1 week after MI surgery for 4 weeks. The results showed that DQ treatment significantly attenuated tachyarrhythmia induction rates and arrhythmia score in post‐MI rats. In echocardiography, DQ improved left ventricular (LV) systolic and diastolic function. Histological assessment revealed that DQ significantly reduced fibrotic areas and myocyte areas, and increased connexin (Cx) 43 positive areas in IBZ. Western blot revealed that DQ treatment significantly reduced the protein expression levels of type I and III collagens, α‐smooth muscle actin (α‐SMA), transforming growth factor‐β1 (TGF‐β1) and Smad3 phosphorylation, while increasing Cx43 amounts. Overall, these findings mainly indicated that DQ intervention regulates interstitial fibrosis, Cx43 expression and myocyte hypertrophy by TGF‐β1/Smad3 pathway in IBZ, inhibits LV remodelling and reduces vulnerability to tachyarrhythmias after MI. This study presents a proof of concept for novel antiarrhythmic strategies in preventing IBZ remodelling, modifying the healed arrhythmogenic substrate and thus reducing susceptibility to ventricular arrhythmias in the late post‐MI period.  相似文献   
959.
960.
Initial functional studies have demonstrated that RNA‐binding motif protein 10 (RBM10) can promote apoptosis and suppress cell proliferation; however, the results of several studies suggest a tumour‐promoting role for RBM10. Herein, we assessed the involvement of RBM10 in lung adenocarcinoma cell proliferation and explored the potential molecular mechanism. We found that, both in vitro and in vivo, RBM10 overexpression suppresses lung adenocarcinoma cell proliferation, while its knockdown enhances cell proliferation. Using complementary DNA microarray analysis, we previously found that RBM10 overexpression induces significant down‐regulation of RAP1A expression. In this study, we have confirmed that RBM10 decreases the activation of RAP1 and found that EPAC stimulation and inhibition can abolish the effects of RBM10 knockdown and overexpression, respectively, and regulate cell growth. This effect of RBM10 on proliferation was independent of the MAPK/ERK and P38/MAPK signalling pathways. We found that RBM10 reduces the phosphorylation of CREB via the AKT signalling pathway, suggesting that RBM10 exhibits its effect on lung adenocarcinoma cell proliferation via the RAP1/AKT/CREB signalling pathway.  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