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   1884篇
  免费   95篇
  国内免费   1篇
  2023年   8篇
  2022年   11篇
  2021年   27篇
  2020年   15篇
  2019年   17篇
  2018年   35篇
  2017年   30篇
  2016年   44篇
  2015年   71篇
  2014年   74篇
  2013年   82篇
  2012年   141篇
  2011年   116篇
  2010年   79篇
  2009年   68篇
  2008年   105篇
  2007年   106篇
  2006年   112篇
  2005年   87篇
  2004年   109篇
  2003年   91篇
  2002年   80篇
  2001年   20篇
  2000年   29篇
  1999年   18篇
  1998年   19篇
  1997年   17篇
  1996年   8篇
  1995年   11篇
  1994年   9篇
  1992年   16篇
  1990年   20篇
  1989年   14篇
  1988年   15篇
  1987年   21篇
  1986年   31篇
  1985年   20篇
  1984年   12篇
  1983年   9篇
  1982年   17篇
  1981年   12篇
  1980年   9篇
  1979年   13篇
  1978年   9篇
  1977年   15篇
  1975年   8篇
  1974年   18篇
  1973年   8篇
  1972年   12篇
  1970年   12篇
排序方式: 共有1980条查询结果,搜索用时 15 毫秒
51.
Three novel morphiceptin analogs, in which Pro in position 2 and/or 4 was replaced by cis‐4‐aminoproline connected with the preceding amino acid through the primary amino group, were synthesized. The opioid receptor affinities, functional assay results, enzymatic degradation studies and experimental and in silico structural analysis of such analogs are presented. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.  相似文献   
52.
53.
54.
Beta-2 microglobulin concentrations were measured in amniotic fluid samples obtained from normal pregnant women at various stages of gestation and complicated pregnancies during weeks 32-42 of gestation by the ELISA method. The concentration of beta-2 microglobulin in amniotic fluid increases markedly up to the 20-24th weeks of pregnancy and reaches a peak during the second trimester, occasionally reaching an eightfold value compared to the maternal serum concentration, while at term the values are similar. The decrease of amniotic fluid beta-2 microglobulin level in the third trimester reflects the maturation of foetal renal tubular function and suggests that this test may be of significance in determining foetal age. Our results revealing elevated concentrations of beta-2 microglobulin in patients with diabetes, toxaemia and placental insufficiency may indicate slower renal maturation of the foetus.  相似文献   
55.
56.
57.
58.
59.
The use of Process Analytical Technology tools coupled with chemometrics has been shown great potential for better understanding and control of mammalian cell cultivations through real-time process monitoring. In-line Raman spectroscopy was utilized to determine the glucose concentration of the complex bioreactor culture medium ensuring real-time information for our process control system. This work demonstrates a simple and fast method to achieve a robust partial least squares calibration model under laboratory conditions in an early phase of the development utilizing shake flask and bioreactor cultures. Two types of dynamic feeding strategies were accomplished where the multi-component feed medium additions were controlled manually and automatically based on the Raman monitored glucose concentration. The impact of these dynamic feedings was also investigated and compared to the traditional bolus feeding strategy on cellular metabolism, cell growth, productivity, and binding activity of the antibody product. Both manual and automated dynamic feeding strategies were successfully applied to maintain the glucose concentration within a narrower and lower concentration range. Thus, besides glucose, the glutamate was also limited at low level leading to reduced production of inhibitory metabolites, such as lactate and ammonia. Consequently, these feeding control strategies enabled to provide beneficial cultivation environment for the cells. In both experiments, higher cell growth and prolonged viable cell cultivation were achieved which in turn led to increased antibody product concentration compared to the reference bolus feeding cultivation.  相似文献   
60.
Sorghum [Sorghum bicolor (L.) Moench] can benefit from accelerated breeding and release of improved varieties through doubled haploid technology. The technology has been used in speeding up the breeding of other major cereals such as wheat, maize and rice, for which generally widely applied optimised protocols exist. A reproducible protocol for the crop, that can overcome genotype dependency and other species-specific challenges such as phenolic exudation is however lacking. This study aimed at sorghum doubled haploids production thereby contributing to the development of an improved protocol. From the 28 hybrid genotypes, both F1 registered- and experimental hybrids involved, this study successfully produced haploids from five genotypes and subsequently, four confirmed doubled-haploid lines on W14mf medium or its modification with 1.0 gl−1 L-proline, 1.0 gl−1 L-asparagine and 1.0 gl−1 KH2PO4. Medium 190-2Cu was used for regeneration and rooting, which occurred successfully, if the calli were transferred on to it less than 7 days after induction, and temperature was maintained at 25˚C under light condition. Genotype dependency was not wholly overcome; however, sorghum’s high tillering ability and abiotic stress tolerance were observed to contribute to attainment of haploid plantlets. Spontaneous diploids producing seeds at rates of upto 80.5% were obtained, therefore eliminating the need for colchicine duplication.  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