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   884篇
  免费   63篇
  2024年   3篇
  2023年   16篇
  2022年   15篇
  2021年   37篇
  2020年   17篇
  2019年   27篇
  2018年   31篇
  2017年   24篇
  2016年   35篇
  2015年   55篇
  2014年   63篇
  2013年   60篇
  2012年   79篇
  2011年   93篇
  2010年   59篇
  2009年   36篇
  2008年   56篇
  2007年   46篇
  2006年   27篇
  2005年   35篇
  2004年   29篇
  2003年   31篇
  2002年   19篇
  2001年   3篇
  2000年   3篇
  1999年   6篇
  1998年   9篇
  1997年   6篇
  1996年   3篇
  1995年   2篇
  1994年   4篇
  1993年   2篇
  1992年   3篇
  1991年   2篇
  1990年   1篇
  1989年   2篇
  1985年   1篇
  1983年   1篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
  1976年   1篇
  1975年   1篇
  1974年   1篇
排序方式: 共有947条查询结果,搜索用时 15 毫秒
1.

Background  

Digital atlases provide a common semantic and spatial coordinate system that can be leveraged to compare, contrast, and correlate data from disparate sources. As the quality and amount of biological data continues to advance and grow, searching, referencing, and comparing this data with a researcher's own data is essential. However, the integration process is cumbersome and time-consuming due to misaligned data, implicitly defined associations, and incompatible data sources. This work addressing these challenges by providing a unified and adaptable environment to accelerate the workflow to gather, align, and analyze the data.  相似文献   
2.
3.
Abstract Azide, an inhibitor of ATPase, and a specific inhibitor of protein export was used in order to select for protein secretion mutants in Acinetobacter calcoaceticus A2. Two such mutants were isolated that were azide-resistant and defective in the general protein transport system. The mutation also conferred additional phenotypic changes, including an inability to grow on minimal media or at 40°C. The existence of protein secretion mutants with a selectable phenotype may be useful for the genetic study of protein export.  相似文献   
4.
5.
InSaccharomyces cerevisiae, most of the cellular chitin is produced by chitin synthase III, which requires the product encoded by theCSD2/CAL1/DIT101/KT12 gene. We have identified, isolated and structurally characterized aCSD2/CAL1/DIT101/KT12 homologue in the filamentous ascomyceteNeurospora crassa and have used a reverse genetics approach to determine its role in vivo. The yeast gene was used as a heterologous probe for the isolation of aN. crassa gene (designatedchs-4) encoding a polypeptide belonging to a class of chitin synthases which we have designated class IV. The predicted polypeptide encoded by this gene is highly similar to those ofS. cerevisiae andCandida albicans. N. crassa strains in whichchs-4 had been inactivated by the Repeat-Induced Point mutation (RIP) process grew and developed in a normal manner under standard growth conditions. However, when grown in the presence of sorbose (a carbon source which induces morphological changes accompanied by elevated chitin content), chitin levels in thechs-4 RIP strain were significantly lower than those observed in the wild type. We suggest that CHS4 may serve as an auxiliary enzyme inN. crassa and that, in contrast to yeasts, it is possible that filamentous fungi may have more than one class IV chitin synthase.A. Beth Din and C. A. Specht contributed equally to this work  相似文献   
6.
ATKINSON, RICHARD L, ROY C BLANK, DONALD SCHUMACHER, NIKHIL V DHURANDHAR, DOUGLAS L RITCH. Long-term drug treatment of obesity in a private practice setting. This study evaluated the long-term efficacy and safety of the combination of phentermine and fenfluramine for the treatment of obesity in a private practice setting. A total of 1388 consecutive, qualified patients presenting to a private general internal medicine practice in Charlotte, NC, were enrolled with eligibility criteria including: age 18 years to 60 years, 20% over “desirable” bodyweight or body mass index <27, no serious medical or psychiatric disease, and no contraindications to drug therapy. Patients were instructed in diet, exercise, and behavior modification techniques and received phentermine (15 mg/day to 30 mg/day) and fenfluramine (20 mg/day to 60 mg/day) continuously for over 3 years. Average duration of treatment was 15. 9 months, and average weight loss at the last visit was 11. 6 kg, or 11. 7% of initial bodyweight. For patients completing 1 year of drug treatment, mean weight loss was 16. 5 kg, or 16% of initial weight. Weight loss persisted for 2 years, but partial regain was seen at 3 years. The dropout rates were 18% at 6 months, 39% at 1 year, 68% at 2 years, and 78% at 3 years. At 1 year, blood pressure of hypertensive patients fell from 151/95 mm Hg to 127/78 mm Hg, and serum cholesterol and triglycerides of hyperlipidemic patients fell by 0. 750 mmol/L (29 mg/dL) and 0. 937 mmol/L (83 mg/dL), respectively. Adverse events were modest. We conclude that, in a private practice setting, long-term treatment of obesity with the combination of phentermine, fenfluramine, and a weight maintenance program is generally safe and effective. More research is needed to determine efficacy and safety for longer than 3 years.  相似文献   
7.
A cross-over trail of debrisoquine and guanethidine in 32 patients showed that both drugs were equally effective in lowering both systolic and diastolic blood pressure. The degree to which they were tolerated by the patients, however, differed greatly. After three months on each drug 18 patients preferred debrisoquine, nine preferred guanethidine, and five showed no particular preference. At current prices the cost of daily treatment to the patient was cheaper with debrisoquine than with guanethidine.  相似文献   
8.
Plant Cell, Tissue and Organ Culture (PCTOC) - The present study reports an optimized protocol for high frequency in vitro plant propagation through direct and indirect organogenesis, phytochemical...  相似文献   
9.
Neurochemical Research - Cerebral ischemic injury is a leading cause of death and long-term disability throughout the world. Peroxisome proliferator-activated receptor gamma (PPAR-?) is a...  相似文献   
10.
Omecamtiv mecarbil (OM), a direct myosin motor activator, is currently being tested as a therapeutic replacement for conventional inotropes in heart failure (HF) patients. It is known that HF patients exhibit dysregulated β-adrenergic signaling and decreased cardiac myosin-binding protein C (cMyBPC) phosphorylation, a critical modulator of myocardial force generation. However, the functional effects of OM in conditions of altered cMyBPC phosphorylation have not been established. Here, we tested the effects of OM on force generation and cross-bridge (XB) kinetics using murine myocardial preparations isolated from wild-type (WT) hearts and from hearts expressing S273A, S282A, and S302A substitutions (SA) in the M domain, between the C1 and C2 domains of cMyBPC, which cannot be phosphorylated. At submaximal Ca2+ activations, OM-mediated force enhancements were less pronounced in SA than in WT myocardial preparations. Additionally, SA myocardial preparations lacked the dose-dependent increases in force that were observed in WT myocardial preparations. Following OM incubation, the basal differences in the rate of XB detachment (krel) between WT and SA myocardial preparations were abolished, suggesting that OM differentially affects the XB behavior when cMyBPC phosphorylation is reduced. Similarly, in myocardial preparations pretreated with protein kinase A to phosphorylate cMyBPC, incubation with OM significantly slowed krel in both the WT and SA myocardial preparations. Collectively, our data suggest there is a strong interplay between the effects of OM and XB behavior, such that it effectively uncouples the sarcomere from cMyBPC phosphorylation levels. Our findings imply that OM may significantly alter the in vivo cardiac response to β-adrenergic stimulation.  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