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   159篇
  免费   6篇
  165篇
  2022年   1篇
  2021年   10篇
  2020年   6篇
  2019年   5篇
  2018年   8篇
  2017年   3篇
  2016年   3篇
  2015年   4篇
  2014年   9篇
  2013年   7篇
  2012年   13篇
  2011年   9篇
  2010年   8篇
  2009年   5篇
  2008年   11篇
  2007年   5篇
  2006年   8篇
  2005年   6篇
  2004年   5篇
  2003年   5篇
  2002年   4篇
  2001年   1篇
  2000年   1篇
  1998年   1篇
  1996年   1篇
  1995年   1篇
  1993年   1篇
  1992年   1篇
  1990年   6篇
  1989年   3篇
  1988年   1篇
  1986年   1篇
  1984年   2篇
  1983年   2篇
  1980年   1篇
  1978年   1篇
  1976年   1篇
  1975年   1篇
  1974年   1篇
  1968年   1篇
  1967年   1篇
  1960年   1篇
排序方式: 共有165条查询结果,搜索用时 15 毫秒
71.
72.
73.
The milking ability of Lacaune ewes was characterised by derived traits of milk flow patterns, in an INRA experimental farm, from a divergent selection experiment in order to estimate the correlated effects of selection for protein and fat yields. The analysis of selected divergent line effects (involving 34 616 data and 1204 ewes) indicated an indirect improvement of milking traits (+17% for maximum milk flow and -10% for latency time) with a 25% increase in milk yield. Genetic parameters were estimated by multi-trait analysis with an animal model, on 751 primiparous ewes. The heritabilities of the traits expressed on an annual basis were high, especially for maximum flow (0.54) and for latency time (0.55). The heritabilities were intermediate for average flow (0.30), time at maximum flow (0.42) and phase of increasing flow (0.43), and low for the phase of decreasing flow (0.16) and the plateau of high flow (0.07). When considering test-day data, the heritabilities of maximum flow and latency time remained intermediate and stable throughout the lactation. Genetic correlations between milk yield and milking traits were all favourable, but latency time was less milk yield dependent (-0.22) than maximum flow (+0.46). It is concluded that the current dairy ewe selection based on milk solid yield is not antagonistic to milking ability.  相似文献   
74.
The work's objective is to answer the question whether there is any possibility of activity inhibition of cysteine peptidases inhibitors playing an important role in key processes accompanying cancer formation, including pancreas. There is a justified speculation that specific inhibitors of these enzymes may inhibit development of cancer processes by inhibiting their activity. In vitro studies confirmed that these enzymes in ascitic fluid were inhibited with egg whites inhibitors even to 90% of their original activity.  相似文献   
75.
Invasive behavior is the pathological hallmark of malignant gliomas, being responsible for the failure of surgery, radiation, and chemotherapy. Matrix metalloproteinases (MMPs) are essential for proper ECM remodeling and invasion. The tumor and metastasis suppressor RECK protein regulates at least three members of the MMPs family: MMP-2, MMP-9, and MT1-MMP. In order to mimic the in vivo invasion process, A172 and T98G, respectively, non-invasive and invasive human glioblastoma cell lines, were cultured onto uncoated (control) or type I collagen gel-coated surface, and maintained for up to 7 days to allow establishment of the invasive process. We show that the collagen substrate causes decreased growth rates and morphological alterations correlated with the invasive phenotype. Electronic transmission microscopy of T98G cells revealed membrane invaginations resembling podosomes, which are typically found in cells in the process of crossing tissue boundaries, since they constitute sites of ECM degradation. Real time PCR revealed higher RECK mRNA expression in A172 cells, when compared to T98G cells and, also, in samples obtained from cultures where the invasive process was fully established. Interestingly, the collagen substrate increases RECK expression in A172 cells and the same tendency is displayed by T98G cells. MMPs-2 and -9 displayed higher levels of expression and activity in T98G cells, and their activities are also upregulated by collagen. Therefore, we suggest that: (1) RECK downregulation is critical for the invasiveness process displayed by T98G cells; (2) type 1 collagen could be employed to modulate RECK expression in glioblastoma cell lines. Since a positive correlation between RECK expression and patients survival has been noted in several types of tumors, our results may contribute to elucidate the complex mechanisms of malignant gliomas invasiveness.  相似文献   
76.
The title compound, which differs from the powerful O-GlcNAcase (OGA) inhibitor GlcNAc-thiazoline only at the chalcogen atom (Se for S), is a much weaker inhibitor in a direct OGA assay. In human cells, however, the selenazoline shows comparable ability to induce hyper-O-GlcNAc-ylation, and the two show similar reduction of insulin-stimulated translocation of glucose transporter 4 in differentiated 3T3 adipocytes.  相似文献   
77.
Summary The linear mitochondrial DNAs of the two infertile algal species Chlamydomonas smithii and C. reinhardtii are co-linear with the exception of a 1 kb intron ( intron) located in the cytochrome b gene of C. smithii. C. smithii also possesses an additional HpaI restriction site (H marker) located in the COXI gene, about 5 kb from the intron. In reciprocal crosses, C. smithii (H ++) × C. reinhardtii (H ), the intron is transmitted to all diploid progeny, whereas the H marker is frequently transmitted either biparentally or paternally depending on whether the C. smithii parent is maternal (mt +) or paternal (mt ). In diploids resulting from artificial fusion between vegetative cells, the absolute transmission of a is accompanied by the frequent transmission of the H + marker, irrespective of the mating type of the parental strains. Finally, in reciprocal crosses between C. smithii (H ++) and recombinant H + clones, the transmission of the H marker is predominantly paternal or biparental. These results allow us to conclude that (1) the a intron behaves as a group I intron whose unidirectional conversion influences the transmission of the H marker; and (2) the mt paternal mitochondrial genome is transmitted more often than the mt +. The mating type has no effect in diploids obtained by artificial fusion.  相似文献   
78.
79.
Biological Trace Element Research - In this study, metabolites involved in the free-biomass filtrates for three endophytic actinomycetes of Streptomyces capillispiralis Ca-1, Streptomyces...  相似文献   
80.
Camel’s milk is an important part of staple diet in several parts of the world, particularly in the arid and semi-arid zones. Camel’s milk is rich in health-beneficial substances, such as bioactive peptides, lactoferrin, zinc, and mono and polyunsaturated fatty acids. These substances could help in the treatment of some important human diseases like tuberculosis, asthma, gastrointestinal diseases, and jaundice. Camel’s milk composition is more variable compared to cow’s milk. The effects of feed, breed, age, and lactation stage on milk composition are more significant in camel. Region and season significantly change the ratio of compounds in camel’s milk. Camel’s whey protein is not only composed of numerous soluble proteins, but also has indigenous proteases such as chymotrypsin A and cathepsin D. In addition to their high nutritional value, these whey proteins have unique characteristics, including physical, chemical, physiological, functional, and technological features that are useful in the food application. The hydrolysis of camel’s milk proteins leads to the formation of bioactive peptides, which affect major organ systems of the body and impart physiological functions to these systems. The camel’s milk has antioxidant, antimicrobial, angiotensin-I-converting enzyme (ACE)-inhibitory peptides, antidiabetic as well as anticholesterol activities.  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