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   1393篇
  免费   129篇
  国内免费   166篇
  2024年   1篇
  2023年   22篇
  2022年   17篇
  2021年   52篇
  2020年   58篇
  2019年   60篇
  2018年   55篇
  2017年   42篇
  2016年   63篇
  2015年   85篇
  2014年   96篇
  2013年   97篇
  2012年   107篇
  2011年   96篇
  2010年   73篇
  2009年   56篇
  2008年   75篇
  2007年   53篇
  2006年   54篇
  2005年   46篇
  2004年   67篇
  2003年   63篇
  2002年   76篇
  2001年   63篇
  2000年   31篇
  1999年   28篇
  1998年   19篇
  1997年   10篇
  1996年   24篇
  1995年   11篇
  1994年   12篇
  1993年   13篇
  1992年   13篇
  1991年   6篇
  1990年   9篇
  1989年   8篇
  1988年   4篇
  1987年   4篇
  1986年   4篇
  1985年   5篇
  1984年   5篇
  1983年   1篇
  1982年   2篇
  1981年   1篇
  1979年   1篇
排序方式: 共有1688条查询结果,搜索用时 61 毫秒
151.
Cao H  Leng X  Li C  Wei Q  Gui J  Cheng H  Zhou R 《Molecular biology reports》2012,39(4):4647-4653
Chinese sturgeon (Acipenser sinensis) is a rare and endangered species and also an important resource for the sturgeon aquaculture industry, however, a few genes have been identified in this species. We report here construction of a pituitary cDNA library from a 24 years old female Chinese sturgeon just after its spawning, and obtained 2,025 ESTs from the library. 885 unique sequences were identified, which were categorized into 12 functional groups. More than half of the unique sequences (57%) do not match with annotated sequences in the public databases. Three of these novel genes were further identified. Notably, a full-length of cDNA (1,143 bp) encoding somatolactin of 232 amino acids was identified. Phylogenetic analysis showed 97% amino acid identity with White sturgeon somatolactin. RT-PCR analysis indicated that the somatolactin mRNA was only detected in pituitary. Pituitary-specific expression of the somatolactin suggested that the protein may play important physiological functions in pituitary-endocrine system of the Chinese sturgeon.  相似文献   
152.
Due to increasing applications of lanthanides (Ln) in industry and daily life, numerous studies confirmed that Ln exposure may result in organ damages in mice and rats, while very few studies focused on several organs damages simultaneously. In order to compare the toxicity of Ln on organs, mice were exposed to LaCl(3), CeCl(3), and NdCl(3) of a dose of 20 mg/kg body weight for consecutive 60 days, respectively, then histopathological changes of liver, kidney, and heart, and their function were investigated. The results showed that long-term exposure to Ln caused cell necrosis and basophilia of liver, ambiguity of renal tubule architecture, congestion of blood vessel and capillary of kidney, and heart hemorrhage. The histopathological changes of liver, kidney, and heart in mice caused by Ce(3+) was most severe; the effect by Nd(3+) was slighter than Ce(3+) but more severe than La(3+). The assay of serum biochemical parameters suggested that Ln exposure severely impaired the functions of liver, kidney, and myocardium in mice. These findings suggested that long-term exposure to Ln resulted in histopathological changes of liver, kidney, and heart, and their function damages. Therefore, we thought that long-term application of the products containing Ln on human should be cautious.  相似文献   
153.
Bombyx mori nucleopolyhedrovirus (BmNPV) causes infection in the silkworm that is often lethal. The infection is hard to prevent, partly because of the nature of the virus particles and partly because of the different strains of B. mori. Titanium dioxide nanoparticles (TiO2 NPs) have been demonstrated to have antimicrobial properties. The present study investigated whether TiO2 NPs added to an artificial diet can increase the resistance of B. mori larvae to BmNPV and examined the molecular mechanism behind any resistance shown. The results indicated that ingested TiO2 NPs decreased reactive oxygen species and NO accumulation in B. mori larvae under BmNPV infection, which in turn led to a decrease in their growth inhibition and mortality. In addition, the TiO2 NPs significantly promoted the expression of resistance-related genes, including those encoding superoxide dismutase, catalase, glutathione peroxidase, acetylcholine esterase, carboxylesterase, heat shock protein 21, glutathione S transferase o1, P53, and transferring and of genes encoding cytochrome p302 and nitric oxide synthase. These findings are a useful addition to the understanding of the mechanism of BmNPV resistance of B. mori larvae in response to TiO2 NPs addition. Such information also provides a theoretical basis for the use of TiO2 NPs in sericulture.  相似文献   
154.
Chang J  Wang M  Gui W  Zhao Y  Yu L  Zhu G 《Zoological science》2012,29(3):181-184
The zebrafish (Danio rerio) has been used as a model for the study of endocrine disrupting chemicals. This study set out to determine the profiles of whole-body thyroxine (T4) and 3,5,3'-triiodothyronine (T3) levels during the development of zebrafish from embryo to adult. Enzyme-linked immunoassay was used to analyze whole-body T4 and T3 contents. The results showed that whole-body T4 and T3 levels remained stable during the pre-hatching period (0-3 d) and increased significantly during early development after hatching. The T3 level peaked at 0.28 ± 0.01 ng g(-1) body weight at 10 days post-fertilization (dpf), and T4 peaked at 0.58 ± 0.09 ng g(-1) body weight at 21 dpf. Both thyroid hormones subsequently declined during later development. This study establishes a baseline for thyroid hormones in zebrafish, which will be vital for the understanding of thyroid hormone functions and in future studies of thyroid toxicants in this species.  相似文献   
155.
The nanos gene family was essential for germ line development in diverse organisms. In the present study, the full-length cDNA of a nanos1 homologue in A. sinensis, Asnanos1, was isolated and characterized. The cDNA sequence of Asnanos1 was 1489 base pairs (bp) in length and encoded a peptide of 228 amino acid residues. Multiple sequence alignment showed that the zinc-finger motifs of Nanos1 were highly conserved in vertebrates. By RT-PCR analysis, Asnanos1 mRNAs were ubiquitously detected in all tissues examined except for the fat, including liver, spleen, heart, ovary, kidney, muscle, intestines, pituitary, hypothalamus, telencephalon, midbrain, cerebellum, and medulla oblongata. Moreover, a specific polyclonal antibody was prepared from the in vitro expressed partial AsNanos1 protein. Western blot analysis revealed that the tissue expression pattern of AsNanos1 was not completely coincided with that of its mRNAs, which was not found in fat, muscle and intestines. Additionally, by immunofluoresence localization, it was observed that AsNanos1 protein was in the cytoplasm of primary oocytes and spermatocytes. The presented results indicated that the expression pattern of Asnanos1 was differential conservation and divergence among diverse species.  相似文献   
156.
Xu X  Hou Y  Yin X  Bao L  Tang A  Song L  Li F  Tsang S  Wu K  Wu H  He W  Zeng L  Xing M  Wu R  Jiang H  Liu X  Cao D  Guo G  Hu X  Gui Y  Li Z  Xie W  Sun X  Shi M  Cai Z  Wang B  Zhong M  Li J  Lu Z  Gu N  Zhang X  Goodman L  Bolund L  Wang J  Yang H  Kristiansen K  Dean M  Li Y  Wang J 《Cell》2012,148(5):886-895
Clear cell renal cell carcinoma (ccRCC) is the most common kidney cancer and has very few mutations that are shared between different patients. To better understand the intratumoral genetics underlying mutations of ccRCC, we carried out single-cell exome sequencing on a ccRCC tumor and its adjacent kidney tissue. Our data indicate that this tumor was unlikely to have resulted from mutations in VHL and PBRM1. Quantitative population genetic analysis indicates that the tumor did not contain any significant clonal subpopulations and also showed that mutations that had different allele frequencies within the population also had different mutation spectrums. Analyses of these data allowed us to delineate a detailed intratumoral genetic landscape at a single-cell level. Our pilot study demonstrates that ccRCC may be more genetically complex than previously thought and provides information that can lead to new ways to investigate individual tumors, with the aim of developing more effective cellular targeted therapies.  相似文献   
157.
Combination therapy had become very popular currently for the diabetes mellitus and its complications, because of long term unreasonable drug use and adverse reaction to human body. In this study, a polysaccharide (ASP) from the roots of Acanthopanax senticosus was evaluated as an adjuvant with metformin for antidiabetic therapy in alloxan-induced diabetic rats. The result identified ASP plus metformin had a more beneficial promotion for relieving the symptoms of diabetes and reversing liver and kidney damage to normal level than only metfomin administration to diabetic rats. The blood glucose, blood lipid (TC and TG), thiobarbituric acid reactive substances (TBARS), AST, ALT, ALP, total bilirubin, creatinine and urea levels in diabetic rats were decreased by combination of ASP and metformin. Furthermore, the body weight, liver glycogen formation, antioxidant substance (GSH) and antioxidant enzyme (SOD and GPX) levels increased evidently in diabetic mice treated with both ASP and metformin. In particular, sometimes ASP plus metformin could significantly reverse the pathophysiologic parameters of diabetic rats to normal level than only metformin administration. Therefore ASP could be developed to a new adjuvant combined with metformin for diabetes mellitus therapy in the future.  相似文献   
158.
159.
160.
Gui D  Guo Y  Wang F  Liu W  Chen J  Chen Y  Huang J  Wang N 《PloS one》2012,7(6):e39824
Glucose-induced reactive oxygen species (ROS) production initiates podocyte apoptosis, which represents a novel early mechanism leading to diabetic nephropathy (DN). Here, we tested the hypothesis that Astragaloside IV(AS-IV) exerts antioxidant and antiapoptotic effects on podocytes under diabetic conditions. Apoptosis, albuminuria, ROS generation, caspase-3 activity and cleavage, as well as Bax and Bcl-2 mRNA and protein expression were measured in vitro and in vivo. Cultured podocytes were exposed to high glucose (HG) with 50, 100 and 200 μg/ml of AS-IV for 24 h. AS-IV significantly attenuated HG-induced podocyte apoptosis and ROS production. This antiapoptotic effect was associated with restoration of Bax and Bcl-2 expression, as well as inhibition of caspase-3 activation and overexpression. In streptozotocin (STZ)-induced diabetic rats, severe hyperglycemia and albuminuria were developed. Increased apoptosis, Bax expression, caspase-3 activity and cleavage while decreased Bcl-2 expression were detected in diabetic rats. However, pretreatment with AS-IV (2.5, 5, 10 mg·kg(-1)·d(-1)) for 14 weeks ameliorated podocyte apoptosis, caspase-3 activation, renal histopathology, podocyte foot process effacement, albuminuria and oxidative stress. Expression of Bax and Bcl-2 mRNA and protein in kidney cortex was partially restored by AS-IV pretreatment. These findings suggested AS-IV, a novel antioxidant, to prevent Glucose-Induced podocyte apoptosis partly through restoring the balance of Bax and Bcl-2 expression and inhibiting caspase-3 activation.  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