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   248篇
  免费   14篇
  国内免费   8篇
林业   18篇
农学   12篇
基础科学   7篇
  54篇
综合类   50篇
农作物   20篇
水产渔业   23篇
畜牧兽医   65篇
园艺   6篇
植物保护   15篇
  2023年   2篇
  2021年   3篇
  2020年   3篇
  2019年   6篇
  2018年   9篇
  2017年   5篇
  2016年   9篇
  2015年   3篇
  2014年   7篇
  2013年   8篇
  2012年   11篇
  2011年   18篇
  2010年   14篇
  2009年   6篇
  2008年   13篇
  2007年   13篇
  2006年   14篇
  2005年   13篇
  2004年   10篇
  2003年   8篇
  2002年   9篇
  2001年   7篇
  2000年   4篇
  1998年   3篇
  1997年   4篇
  1995年   2篇
  1994年   3篇
  1993年   3篇
  1992年   3篇
  1991年   6篇
  1990年   4篇
  1989年   7篇
  1988年   3篇
  1987年   5篇
  1985年   2篇
  1984年   3篇
  1983年   2篇
  1982年   1篇
  1979年   1篇
  1978年   1篇
  1976年   1篇
  1975年   1篇
  1973年   2篇
  1970年   2篇
  1969年   1篇
  1968年   1篇
  1967年   2篇
  1965年   1篇
  1964年   4篇
  1963年   4篇
排序方式: 共有270条查询结果,搜索用时 15 毫秒
61.
The aim of this study was to systematically examine the inhibitory mechanisms of C-phycocyanin (C-PC), one of the major phycobiliproteins of Spirulina platensis (a blue-green alga), in platelet activation. In this study, C-PC concentration-dependently (0.5-10 nM) inhibited platelet aggregation stimulated by agonists. C-PC (4 and 8 nM) inhibited intracellular Ca2+ mobilization and thromboxane A2 formation but not phosphoinositide breakdown stimulated by collagen (1 microg/mL) in human platelets. In addition, C-PC (4 and 8 nM) markedly increased levels of cyclic GMP and cyclic GMP-induced vasodilator-stimulated phosphoprotein (VASP) Ser(157) phosphorylation. Rapid phosphorylation of a platelet protein of Mw 47,000 (P47), a marker of protein kinase C activation, was triggered by phorbol-12,13-dibutyrate (150 nM). This phosphorylation was markedly inhibited by C-PC (4 and 8 nM). In addition, C-PC (4 and 8 nM) markedly reduced the electron spin resonance (ESR) signal intensity of hydroxyl radicals in collagen (1 microg/mL)-activated platelets. The present study reports on a novel and very potent (in nanomolar concentrations) antiplatelet agent, C-PC, which is involved in the following inhibitory pathways: (1) C-phycocyanin increases cyclic GMP/VASP Ser157 phosphorylation and subsequently inhibits protein kinase C activity, resulting in inhibition of both P47 phosphorylation and intracellular Ca2+ mobilization, and (2) C-PC may inhibit free radicals (such as hydroxyl radicals) released from activated platelets, which ultimately inhibits platelet aggregation. These results strongly indicate that C-PC appears to represent a novel and potential antiplatelet agent for treatment of arterial thromboembolism.  相似文献   
62.
Our aim was to evaluate the inspection of arriving passengers for the illegal transport of animal products through the international airport into Taiwan. Passenger-violation data were retrieved from the Bureau of Animal and Plant Health Inspection and Quarantine (BAPHIQ) in Taiwan. Monte Carlo simulations with 5000 iterations were applied to estimate the predicted violation numbers considering factors such as passenger's nationality/ethnicity, sex, and monthly statistics of violations. The results showed that Chinese-related passengers and passengers from South East Asian countries have a relatively higher potential risk for incurring violations during the period from Christmas to Chinese Lunar New Year. Most monthly estimated violation risks are significantly higher than observed violation risks in 2001 and 2002, except April, July, and August. Due to the low sensitivity of the current detection system (reflected by the higher estimated violation risks and a two-fold detection increase after the implementation of an inspection service using detector dogs), we recommend additional preventive measures be taken.  相似文献   
63.
1. The effect of lactic acid marination at 5°C on post mortem changes in breast muscle pectoralis major of spent layer Tsaiya duck was studied.

2. Myofibrils were prepared from 0.1 M and 0.2 M lactic acid marinated muscle and control (non‐marinated samples) sampled at 0, 1, 3, 7 and 14 d post mortem.

3. Changes in myofibril fragmentation index (MFI), myofibrillar proteins and Z‐line structure were examined.

4. Marination of duck breast muscle in lactic acid at 5°C enhanced fragmentation of myofibrils and degradation of myofibrillar proteins and Z‐line structure as compared to control samples.

5. In summary, lactic acid marination at 5°C can accelerate the post mortem degradation of myofibrils in Tsaiya duck breast muscle.  相似文献   

64.
65.
采用聚丙烯酰胺凝胶电泳 (PAGE)对 37头甘肃黑猪合成系猪的转铁蛋白 (Tf)、前白蛋白 (Pa)、脂酶 (Es)、淀粉酶 1 (Am1 )、淀粉酶 2(Am2 ) 5个蛋白质基因座的多态性进行了检测。并运用通用线性模型分析了这 5个蛋白质基因座的共 1 7种基因型对初生重、 45日龄内平均日增重的相关效应。结果表明Am1AA型具有显著提高初生重的效应 ,PaAA型具有显著提高 45日龄内平均日增重的效应。因此这 2个位点可望用于标记辅助选择。  相似文献   
66.
The complete nucleotide sequences of the S1 and N genes of three Japanese and one Taiwanese field strains of IBV are reported. These Japanese strains were found to have S1 sequences most similar to those of Australian strains and N sequences most similar to those of North American strains. This result suggested that these Japanese strains might all be recombinant viruses derived from recombination of Australia- and North America-related viruses. Moreover, the S1 proteins of all these Japanese and Taiwanese strains exhibit only a limited sequence homology to strains of Massachusetts and Connecticut serotypes that have been commonly used as vaccine strains. This result high lightens the importance of development of vaccines based on the local strains of IBV.  相似文献   
67.
Yellow cypress (Chamaecyparis obtusa (Siebold & Zucc.) Endl. var. formosana (Hayata) Rehder) is the predominant tree species of Taiwan's nutrient-poor, mountain fog forests. Little is known about the potential contribution of solute uptake from fog to the overall nutrition of these trees. Shoots of yellow cypress seedlings were misted with artificial fog containing the tracer rubidium (Rb) in laboratory and field experiments to determine if there is solute uptake from the fog. After misting shoots for six weeks, substantial amounts of tracer were detected in unexposed roots by inductively coupled plasma mass spectroscopy bulk analysis. Possible routes of entry were examined by element imaging with energy dispersive X-ray analysis. Direct uptake of the tracer into leaves across the cuticle and epidermis was small, excluding this as the major uptake path. Accumulations of Rb were found on leaf surfaces along the edges of the leaves. The almost daily changes in fog coverage and air humidity may enhance the accumulation of fog solutes at leaf edges. Accumulation of Rb was also found in narrow clefts between opposite leaves and between the outermost and underlying alternating stacked leaves. The clefts provide a direct passage from the leaf surface to the space beneath the imbricate leaves and the underlying alternate leaves, possibly facilitating solute uptake from fog, which in turn may contribute to the nutrition of yellow cypress.  相似文献   
68.
Japanese oak wilt (JOW) has been prevalent in Japan since the late 1980s. Infections of the fungus, Raffaelea quercivora Kubono et Shin. Ito, which is transmitted by an ambrosia beetle [Platypus quercivorus (Murayama)], can cause JOW. Although R. quercivora, P. quercivorus, and oak trees are distributed in other Asia–Pacific countries, the incidence of JOW has not been reported outside Japan. In this study, we collected R. quercivora isolates from 5 Asian countries, including Japan, and compared their ability to induce sapwood discoloration by inoculating Q. serrata logs. The tangential widths of the discoloration in sapwoods inoculated with non-Japanese isolates were equivalent to or greater than those of the 2 Japanese isolates. This indicates that a lack of JOW incidence outside Japan is not because of the lowered ability of R. quercivora to spread discoloration compared with the Japanese isolates. Statistical analyses of the relationship between discoloration and phylogeny based on DNA sequences of actin and chitin synthase showed that the discoloration width was independent of phylogenetic relatedness among the isolates. To discuss why the occurrence of JOW has not been reported outside Japan, further studies (e.g., on host susceptibility and P. quercivorus aggression) throughout Asia are needed.  相似文献   
69.
In zebrafish, UV exposure leads to fin malformation phenotypes including fin reduction or absence. The present study evaluated UV-protective activities of comfrey leaves extracts in a zebrafish model by recording fin morphological changes. Chemopreventive effects of comfrey leave extracts were evaluated using Kaplan-Meier analysis and Cox proportional hazards regression. The results showed that (1) the mean times of return to normal fin in the UV+comfrey (50 and 100 ppm) groups were 3.43 and 2.86 days and were quicker compared with that in the UV only group (4.21 days); (2) zebrafish fins in the UV+comfrey (50 and 100 ppm) groups were 2.05 and 3.25 times more likely to return to normal than those in the UV only group; and (3) comfrey leave extracts had UV-absorbance abilities and significantly reduced ROS production in UV-exposed zebrafish embryos, which may attenuate UV-mediated apoptosis. In conclusion, comfrey leaves extracts may have the potential to be developed as UV-protective agents to protect zebrafish embryos from UV-induced damage.  相似文献   
70.
Myxovirus-like structures in a case of human chronic polymyositis   总被引:11,自引:0,他引:11  
S M Chou 《Science (New York, N.Y.)》1967,158(807):1453-1455
Intranuclear and intracytoplasmic aggregates of filaments with tubular structures and transverse striations occurred in muscle tissues biopsied from a patient with chronic polymyositis. The filamentous tubules bear a close resemblance to the incomplete form of myxovirus in which the envelope is missing. Three biopsies from the same patient, taken during a period of 1(1/2) years, all revealed these structures. This finding provides presumptive evidence that a chronic persistent viral infection may be involved in the pathogenesis of chronic polymyositis.  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