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   647篇
  免费   43篇
  国内免费   2篇
  2023年   16篇
  2022年   17篇
  2021年   41篇
  2020年   22篇
  2019年   30篇
  2018年   30篇
  2017年   20篇
  2016年   27篇
  2015年   33篇
  2014年   44篇
  2013年   68篇
  2012年   54篇
  2011年   37篇
  2010年   28篇
  2009年   17篇
  2008年   25篇
  2007年   17篇
  2006年   20篇
  2005年   17篇
  2004年   16篇
  2003年   11篇
  2002年   9篇
  2001年   16篇
  2000年   14篇
  1999年   9篇
  1998年   12篇
  1997年   7篇
  1996年   5篇
  1995年   4篇
  1994年   5篇
  1993年   1篇
  1992年   3篇
  1989年   1篇
  1988年   1篇
  1987年   2篇
  1984年   3篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1979年   1篇
  1976年   2篇
  1973年   1篇
  1971年   1篇
  1967年   1篇
  1872年   1篇
排序方式: 共有692条查询结果,搜索用时 312 毫秒
1.
Reactive oxidative species (ROS) toxicity remains an undisputed cause and link between Alzheimer’s disease (AD) and Type-2 Diabetes Mellitus (T2DM). Patients with both AD and T2DM have damaged, oxidized DNA, RNA, protein and lipid products that can be used as possible disease progression markers. Although the oxidative stress has been anticipated as a main cause in promoting both AD and T2DM, multiple pathways could be involved in ROS production. The focus of this review is to summarize the mechanisms involved in ROS production and their possible association with AD and T2DM pathogenesis and progression. We have also highlighted the role of current treatments that can be linked with reduced oxidative stress and damage in AD and T2DM.  相似文献   
2.
This study was designed to evaluate the efficacy of Buffalo Rat Liver cells (BRLC) monolayers in supporting the development of in vitro matured and fertilized (IVM/IVF) bovine oocytes through to the hatched blastocyst stage compared to the commonly used co-culture system of bovine oviduct epithelial cells (BOEC). Cumulus oocyte complexes (COCs) obtained from 2- to 6-mm ovarian follicles at slaughter were matured for 24 h in TCM-199 supplemented with FBS and hormones (FSH, LH and estradiol 17-beta). In vitro fertilization (IVF) was performed using 1 x 10(6) percoll separated frozen-thawed spermatozoa in 1 ml of IVF-TL medium containing 18 to 20 matured oocytes. After 20 to 22 h of sperm exposure, 584 presumptive zygotes in 2 separate trials were randomly assigned to 3 treatment groups (BRLC co-culture, BOEC co-culture and control, consisting of medium alone). Zygotes were cultured in CZB media, a simple semi-defined medium, without glucose for the first 2 d, transferred to M199/FBS (TCM-199-HEPES supplemented with 20% HTFBS, 1 mM Sodium pyruvate), and cultured for an additional 8 days. Cleavage and development to morula and various blastocyst stages were recorded between d 3 and 11 after the start of IVF. Overall average cleavage rate was 75% (440 584 ) and did not vary across the treatments or trials. The proportion of embryos that reached the morula stage in both co-culture systems did not differ (P > 0.05) and was significantly higher (P > 0.05) compared to the control group. However, the percentage of the number of blastocysts, expanded blastocysts and hatched blastocysts varied across the treatment groups (P < 0.05), with the highest results obtained in the BRLC co-culture system. The production of blastocysts in BOEC co-culture was inconsistent between the 2 trials where a significant difference (40.6 vs 53.0%; P > 0.05) was observed. Rate of development to the blastocyst stage was similar between the 2 co-culture systems, with most of the embryos reaching the blastocyst stage by d 8 post insemination. The results of this study show that BRLC from a commercially available established cell line offer a more reliable alternative to a BOEC co-culture system for in vitro maturation, fertilization and culture of bovine embryos.  相似文献   
3.
Development of 8-cell bovine embryos derived from in vitro matured/in vitro fertilized (IVM/IVF) oocytes was evaluated in two simple, serum-free media (CZB and SOM) with buffalo rat liver cells co-culture (BRLC) or after conditioning compared to a commonly used, serum-supplemented complex medium TCM-199. In a 3 x 4 factorial design, 578 eight-cell embryos were randomly assigned to 12 treatment groups. The factors were: first, type of culture medium (M199/FBS, CZBg and SOM), and second, the use of BRLC (as co-culture or to condition media for 24 hr and 48 hr) and unconditioned media. Development to morula was not affected by the type of medium, but co-culture and 48 hr conditioning within media type resulted in better development when compared to the 24-hr conditioned or unconditioned groups. Blastocyst development in SOM (38.9%) was different (P < 0.05) than in CZBg (46.6%) and M199/FBS (48.7%) and was lowest in the unconditioned group (27.8%) followed by 24 hr conditioned (33.3%), 48 hr (56.3%), and co-culture (59.6%). No blastocyst expansion was observed with unconditioned media and 24 hr conditioned SOM. Significant differences (P < 0.05) were found among all treatment groups except the co-culture and 48-hr conditioned groups. Hatching occurred only with co-culture and 48-hr conditioned groups of M199/FBS and CZBg media. These data show that CZB with glucose conditioned by BRLC monolayers for 48 hr can support the development of IVM/IVF produced bovine embryos to blastocyst compared to culture in TCM-199 with serum. © 1994 Wiley-Liss, Inc.  相似文献   
4.
The effect of neurotensin on submaximally-stimulated hepatobiliary and pancreatic secretion was studied in 6 healthy subjects. An intravenous infusion of neurotensin 1.4 ± 0.3 pmol/kg/min, designed to reproduce plasma neurotensin immunoreactivity levels within the physiological range, produced a significant increase in pancreatic bicarbonate output. Plasma concentrations of pancreatic polypeptide rose by 83 ± 16 pmol/l and were associated with a small reduction in trypsin, but no significant change in bilirubin outputs.  相似文献   
5.
The effects of Russell's viper venom on blood coagulation, platelets and the fibrinolytic enzyme system were studied in rabbits after injecting repeated doses of 0.05 MLD of the venom. Thrombocytopenia was the earliest change to appear. It was followed by rise in serum fibrinogen degradation products and prolongation of prothrombin time, activated partial thromboplastin time and thrombin time indicating a progressive consumption coagulopathy and activation of fibrinolysis. Red blood cell morphology was unchanged during the first three weeks; whereas the fragmentation appeared after the fourth week and it increased in severity with further envenomations, i.e. when chronic DIC was established.  相似文献   
6.
Water is essential for the growth period of crops; however, water unavailability badly affects the growth and physiological attributes of crops, which considerably reduced the yield and yield components in crops. Therefore, a pot experiment was conducted to investigate the effect of foliar phosphorus (P) on morphological, gas exchange, biochemical traits, and phosphorus use efficiency (PUE) of maize (Zea mays L.) hybrids grown under normal as well as water deficit situations at the Department of Agronomy, University of Agriculture Faisalabad, Pakistan in 2014. Two different treatments (control and P @ 8 kg ha−1 ) and four hybrids (Hycorn, 31P41, 65625, and 32B33) of maize were tested by using a randomized complete block design (RCBD) with three replications. Results showed that the water stress caused a remarkable decline in total soluble protein (9.7%), photosynthetic rate (9.4%) and transpiration rate (13.4%), stomatal conductance (10.2%), and internal CO2 rate (20.4%) comparative to well-watered control. An increase of 37.1%, 36.8%, and 24.5% were recorded for proline, total soluble sugar, and total free amino acid, respectively. However, foliar P application minimized the negative impact of drought by improving plant growth, physio-biochemical attributes, and PUE in maize plants under water stress conditions. Among the hybrids tested, the hybrid 6525 performed better both under stress and non-stress conditions. These outcomes confirmed that the exogenous application of P improved drought stress tolerance by modulating growth, physio-biochemical attributes, and PUE of maize hybrids.  相似文献   
7.
Globally among biotic stresses, diseases like blight, rust and blast constitute prime constraints for reducing wheat productivity especially in Bangladesh. For sustainable productivity, the development of disease-resistant lines and high yielding varieties is vital and necessary. This study was conducted using 122 advanced breeding lines of wheat including 21 varieties developed by Bangladesh Wheat and Maize Research Institute (BAMRI) with aims to identify genotypes having high yield potential and resistance to leaf blight, leaf rust and blast diseases. These genotypes were evaluated for resistance against leaf blight and leaf rust at Dinajpur and wheat blast at Jashore under field condition. Out of 122 genotypes tested, 20 lines were selected as resistant to leaf blight based on the area under the diseases progress curve (AUDPC) under both irrigated timely sown (ITS) and irrigated late sown (ILS) conditions. Forty-two genotypes were found completely free from leaf rust infection, 59 genotypes were identified as resistant, and 13 genotypes were identified as moderately resistant to leaf rust. Eighteen genotypes were immune against wheat blast, 42 genotypes were categorized as resistant, and 26 genotypes were identified as moderately resistant to wheat blast. Molecular data revealed that the 16 genotypes showed a positive 2NS segment among the 18 immune genotypes selected against wheat blast under field conditions. The genotypes BAW 1322, BAW 1295, and BAW 1203 can be used as earlier maturing genotypes and the genotypes BAW 1372, BAW 1373, BAW 1297 and BAW 1364 can be used for lodging tolerant due to short plant height. The genotypes WMRI Gom 1, BAW 1349 and BAW 1350 can be selected for bold grain and the genotypes WMRI Gom 1, BAW 1297, BAW 1377 can be used as high yielder for optimum seeding condition but genotypes BAW 1377 and BAW 1366 can be used for late sown condition. The selected resistant genotypes against specific diseases can be used in the further breeding program to develop wheat varieties having higher disease resistance and yield potential.  相似文献   
8.

Plant-derived smoke plays a key role in plant growth. Proteomic technique was used for underlying mechanisms of plant-derived smoke on the growth of soybean (Glycine max L.) under flooding stress. The length and weight of soybean root increased with 2000 parts per million plant-derived smoke under flooding stress within 4 days. Altered proteins by plant-derived smoke treatment under flooding stress were mainly related to protein metabolism, stress, and redox. Furthermore, proteins related to mitochondrial electron transport chain decreased by flooding stress; however, they increased by addition of plant-derived smoke under flooding stress. Based on the results of proteomic analysis, confirmation experiments were performed. ATPase abundance and ATP content increased with the treatment of plant-derived smoke under flooding stress. Furthermore, the ascorbate/glutathione cycle was activated with the treatment of plant-derived smoke under flooding stress. These results suggest that plant-derived smoke improves the root growth of soybean with energy production and reactive oxygen scavenging even if it is under flooding stress, which might positively regulate soybean tolerance towards flooding stress.

  相似文献   
9.
The continuous increase in global population prompts increased wheat production. Future wheat (Triticum aestivum L.) breeding will heavily rely on dissecting molecular and genetic bases of wheat yield and related traits which is possible through the discovery of quantitative trait loci (QTLs) in constructed populations, such as recombinant inbred lines (RILs). Here, we present an evaluation of 92 RILs in a bi-parental RIL mapping population (the International Triticeae Mapping Initiative Mapping Population [ITMI/MP]) using newly generated phenotypic data in 3-year experiments (2015), older phenotypic data (1997–2009), and newly created single nucleotide polymorphism (SNP) marker data based on 92 of the original RILs to search for novel and stable QTLs. Our analyses of more than 15 unique traits observed in multiple experiments included analyses of 46 traits in three environments in the USA, 69 traits in eight environments in Germany, 149 traits in 10 environments in Russia, and 28 traits in four environments in India (292 traits in 25 environments) with 7584 SNPs (292 × 7584 = 2 214 528 data points). A total of 874 QTLs were detected with limit of detection (LOD) scores of 2.01–3.0 and 432 QTLs were detected with LOD > 3.0. Moreover, 769 QTLs could be assigned to 183 clusters based on the common markers and relative proximity of related QTLs, indicating gene-rich regions throughout the A, B, and D genomes of common wheat. This upgraded genotype–phenotype information of ITMI/MP can assist breeders and geneticists who can make crosses with suitable RILs to improve or investigate traits of interest.  相似文献   
10.
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