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   1627篇
  免费   109篇
  国内免费   5篇
  2023年   13篇
  2022年   25篇
  2021年   62篇
  2020年   30篇
  2019年   37篇
  2018年   33篇
  2017年   24篇
  2016年   51篇
  2015年   107篇
  2014年   92篇
  2013年   99篇
  2012年   126篇
  2011年   121篇
  2010年   82篇
  2009年   75篇
  2008年   90篇
  2007年   91篇
  2006年   74篇
  2005年   61篇
  2004年   64篇
  2003年   56篇
  2002年   43篇
  2001年   18篇
  2000年   9篇
  1999年   8篇
  1998年   15篇
  1997年   13篇
  1996年   14篇
  1995年   12篇
  1994年   5篇
  1993年   12篇
  1992年   7篇
  1991年   13篇
  1990年   11篇
  1989年   5篇
  1988年   6篇
  1987年   5篇
  1986年   7篇
  1985年   10篇
  1984年   9篇
  1983年   10篇
  1982年   8篇
  1981年   5篇
  1980年   6篇
  1979年   6篇
  1978年   5篇
  1977年   5篇
  1975年   4篇
  1971年   4篇
  1954年   4篇
排序方式: 共有1741条查询结果,搜索用时 15 毫秒
71.
72.
73.
Objective: In this study, we investigated about the potential of serum ferritin as a complementary diagnostic biomarker of polycystic ovarian syndrome (PCOS) by performing a meta-analysis of existing literature.

Materials and methods: Eleven studies written in English were retrieved up to 30 June 2018. Data were extracted from the selected studies by two of the authors and was subjected to statistical analysis. Levels of serum ferritin were compared between women with PCOS and controls using the standardized mean difference (SMD) and 95% confidence interval (CI). Subgroup analysis was also performed and stratified by ethnicity (Asians versus Caucasians).

Results: Overall post-outlier outcomes indicated that elevated serum ferritin is strongly associated with PCOS (SMD: 0.52; 95% CI: 0.40–0.64; PA?=?10?5). Subgroup analysis by ethnicity showed no significant difference between Asian and Caucasian population. Post-outlier receiving operations characteristics curve were plotted and showed that values for serum ferritin showed good potential in discriminating patients with and without PCOS (AUC?=?0.827, p?=?0.006).

Conclusion: Our findings suggest that high serum ferritin level is significantly associated with PCOS and its potential as a biomarker is evident in its high diagnostic accuracy. However, additional studies are needed to confirm our claims.  相似文献   

74.
75.
The study presents a screening method used to identify the influential parameters of a lower limb model including ligaments, at low numerical cost. Concerning multibody kinematics optimisation, the ligament parameters (isometric length) were found the most influential ones in a previous study. The screening method tested if they remain influential with minimised length variations. The most important parameters for tibiofemoral kinematics were the skin markers, segment lengths and joint parameters, including two ligaments. This was confirmed by a quantitative sensitivity analysis. The screening method has the potential to be used as a stand-alone procedure for a sensitivity analysis.  相似文献   
76.
Kluyveromyces marxianus CCT 7735 has been used to produce ethanol, aromatic compounds, enzymes and heterologous proteins besides assimilates lactose as carbon source. Its genome has 10.7 Mb and encodes 4787 genes distributed in 8 nuclear chromosomes and one mitochondrial. Contrary to Kluyveromyces lactis, which has a unique LAC12 gene (encodes lactose permease), K. marxianus possesses four. The presence of degenerated copies and Solo-LTRs related to retrotransposon TKM close to the LAC12 genes in K. marxianus indicates ectopic recombinations. The Lac12 permeases of K. marxianus and K. lactis are conserved, however the conservation is higher between the copy of the left side of the chromosome three and the unique copy of K. lactis, indicating that this copy is the ancestor. The expression of the four LAC12 genes occurred in aerobiosis and hypoxia. Notably, the high lactose consumption in hypoxia seems to be related to the high expression of the LAC12 genes.  相似文献   
77.
Inhibition of animal cell phospholipid biosynthesis has been proposed for anticancer and antiviral therapies. Using CHOK1 derived cell lines, we have developed and used a cell-based high-throughput procedure to screen a 1280 compound, small molecule library for inhibitors of phospholipid biosynthesis. We identified tyrphostin AG 879 (AG879), which inhibited phospholipid biosynthesis by 85–90% at a concentration of 10 μM, displaying an IC50 of 1–3 μM. The synthesis of all phospholipid head group classes was heavily affected. Fatty acid biosynthesis was also dramatically inhibited (90%). AG879 inhibited phospholipid biosynthesis in all additional cell lines tested, including MDCK, HUH7, Vero, and HeLa cell lines. In CHO cells, AG879 was cytostatic; cells survived for at least four days during exposure and were able to divide following its removal. AG879 is an inhibitor of receptor tyrosine kinases (RTK) and inhibitors of signaling pathways known to be activated by RTK's also inhibited phospholipid biosynthesis. We speculate that inhibition of RTK by AG879 results in an inhibition of fatty acid biosynthesis with a resulting decrease in phospholipid biosynthesis and that AG879's effect on fatty acid synthesis and/or phospholipid biosynthesis may contribute to its known capacity as an effective antiviral/anticancer agent.  相似文献   
78.
The paper presents multiplex panels of polymorphic microsatellites for two closely related cryptic species Pipistrellus pipistrellus and Pipistrellus pygmaeus. We tested the cross‐species amplification of 34 microsatellite loci, originally developed for five vespertilionid bat species. Ten and nine polymorphic loci in P. pipistrellus (mean number of alleles per locus = 10.5) and P. pygmaeus (8.1), respectively, in three multiplex polymerase chain reactions per species were amplified. All loci can be analysed in a single fragment analysis and can be used as markers to the study of evolution and the ecology of structured populations of socially living bats.  相似文献   
79.
80.
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