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   751篇
  免费   25篇
  2021年   6篇
  2020年   4篇
  2019年   6篇
  2018年   8篇
  2017年   4篇
  2016年   5篇
  2015年   13篇
  2014年   15篇
  2013年   50篇
  2012年   32篇
  2011年   30篇
  2010年   25篇
  2009年   27篇
  2008年   47篇
  2007年   45篇
  2006年   51篇
  2005年   29篇
  2004年   40篇
  2003年   36篇
  2002年   29篇
  2001年   14篇
  2000年   10篇
  1999年   16篇
  1998年   13篇
  1996年   8篇
  1995年   8篇
  1994年   13篇
  1993年   8篇
  1992年   6篇
  1991年   5篇
  1990年   8篇
  1989年   7篇
  1988年   5篇
  1987年   9篇
  1986年   11篇
  1985年   13篇
  1984年   11篇
  1983年   15篇
  1982年   14篇
  1981年   8篇
  1980年   6篇
  1979年   5篇
  1978年   7篇
  1977年   5篇
  1976年   4篇
  1975年   10篇
  1973年   4篇
  1972年   5篇
  1970年   3篇
  1968年   4篇
排序方式: 共有776条查询结果,搜索用时 15 毫秒
41.
Inhibitory effect of monoclonal antibodies on the growth of Babesia caballi   总被引:2,自引:0,他引:2  
Monoclonal antibodies (mAbs) were produced against Babesia caballi (USDA strain) to define a species-specific antigen for use in diagnosis and vaccine development. Eight positive clones of B. caballi mAbs determined by indirect immunofluorescent antibody test were selected for purification and further characterisation. Confocal laser microscopy showed that the antigens recognised by the mAbs were located on the surface/cytoplasm, central part, and/or anterior end of B. caballi parasites, with five different reactive patterns. These mAbs seemed to be species-specific, since they did not cross-react with Babesia equi-infected erythrocytes or uninfected erythrocytes. In Western blotting analysis, 18, 20, 34, 36, 48, and 155 kDa proteins of B. caballi merozoites were recognised by six different mAbs. When added to in vitro cultures, four of the mAbs significantly inhibited the in vitro growth of B. caballi parasites. These results provide a rationale for evaluating antigens for the development of diagnostic methods or vaccines.  相似文献   
42.
Doxorubicin (DOX=adriamycine), an effective chemotherapeutic agents for cancers, has severe cardiotoxicity. In the paresent study, we examined the protective effect of thermal preconditioning (TP) against apoptosis of rat cardiac muscle cells induced by DOX. Treatment with DOX (10 microM) for 24 hrs resulted in apoptosis of cardiac muscle cells, which was evaluated by examining "DNA ladder" formation and TUNEL staining. The number of TUNEL-positive cells was significantly decreased in cells subjected to TP by incubation at 42 degrees C for 30 min, 24 hrs prior to DOX-treatment. Antisense oligonucleotides of the heat shock protein (HSP) 70 blunted this effect. These results indicate that DOX-induced apoptosis in cardiac muscle cells is prevented by TP, at least in part, via a HSP70-mediated mechanism.  相似文献   
43.
The cell line designated HHUS was established from human uterine cervical keratinizing squamous cell carcinoma. The HHUS cell line was subcultivated more than 70 times within 3 years. The cultured cells, polygonal or spindle, with neoplastic and pleomorphic features, appeared epithelial in shape, with a pavement-like arrangement and grew in multi-layers without contact inhibition. The chromosome number was varied from 40 to 88, and the modal number was stable in diploid range. The cultured cells produced keratinizing squamous cell carcinomas by heterotransplantation into the subcutis of nude mice. The HHUS cells were characterized as producing large amounts of SCC, in vitro and possessing HPV-59 DNA genomes.  相似文献   
44.
In this study, we have examined the anti-inflammatory actions of royal jelly (RJ) at a cytokine level. When supernatants of RJ suspensions were added to a culture of mouse peritoneal macrophages stimulated with lipopolysaccharide and IFN-gamma, the production of proinflammatory cytokines, such as TNF-alpha, IL-6, and IL-1, was efficiently inhibited in a dose-dependent manner without having cytotoxic effects on macrophages. This suggests that RJ contains factor(s) responsible for the suppression of proinflammatory cytokine secretion. We named the factor for honeybees RJ-derived anti-inflammatory factor (HBRJ-AIF), and further investigated the molecular aspects of it. Size fractionation study showed that HBRJ-AIF is composed of substances of low (< 5 kDa) and high (> 30 kDa) molecular weights, with the former being a major component. Chromatographic analysis showed that MRJP3 is one candidate for the HBRJ-AIF with high molecular weights. Thus, our results suggest that RJ has anti-inflammatory actions through inhibiting proinflammatory cytokine production by activated macrophages.  相似文献   
45.
We have previously shown that royal jelly (RJ) promoted collagen production by skin fibroblasts in the presence of ascorbic acid-2-O-alpha-glucoside (AA-2G). In this study, we purified the honeybee RJ-derived collagen production-promoting factor (HBRJ-CPF) from an alkali-solubilized fraction of RJ by C18 reverse-phase column chromatography. The elution profile by the C18 column chromatography and the molecular mass of the purified HBRJ-CPF material coincided with those of 10-hydroxy-2-decenoic acid (10H2DA). We then examined the collagen production-promoting activities of several commercially available fatty acids contained in RJ. We found that 10H2DA and 10-hydroxydecanoic acid increased the collagen production in a dose-dependent manner. Furthermore, 10H2DA induced the fibroblast cell line, NHDF, to produce transforming growth factor-beta 1 (TGF-beta 1) which is an important factor for collagen production. As expected, the collagen production-promoting activity of 10H2DA was neutralized by the anti-TGF-beta 1 antibody. These result suggest that HBRJ-CPF identified as 10H2DA promoted the collagen production of AA-2G-treated fibroblasts by inducing TGF-beta 1 production.  相似文献   
46.
Thickness shear mode quartz-crystal resonator coated with plasma polymer films (PPFs) produced by radio-frequency sputtering of biomaterials and synthetic polymers were examined with respect to their abilities to continuously monitor indoor air. We confirmed the sensory capabilities of an array of PPF sensors to aromas emitted from essential oils at concentrations as low as the detection threshold of human olfaction. Changes in humidity induced a drift in the response curves of PPF sensors. On the contrary, volatile compounds exhibited pulse signals. The pulse signals of a D-phenylalanine sensor and a polyethylene sensor were synchronous, but the direction of the peaks was inverted in most cases. Compared with a photo-ionization detector sensor, the PPF sensors were able to detect subtle changes in the concentrations of volatile compounds in indoor air.  相似文献   
47.
Based on a common pharmacophore model and the hypothesis that the baccatin core of taxoids is a scaffold securing the proper orientation of the side chains, a bicyclic alkaloid scaffold was designed as a baccatin surrogate. Using this scaffold, two novel macrocyclic and open-chain 'taxoid-mimicking' compounds were synthesized. Two of these 'taxoid-mimics', 2 and 3, were found to possess cytotoxicity with micromolar level IC50 values against human breast cancer cell lines.  相似文献   
48.
Serine proteinases are one of the largest proteolytic families of enzymes, and have diverse cellular activities in mammalian tissues. We report here the cloning and molecular characterization of a cDNA encoding the serine proteinase of the hard tick Haemaphysalis longicornis (HlSP). The HlSP cDNA is 1570 bp long and the deduced precursor protein consists of 464 amino acids with a predicted molecular mass of 50.4 kDa and a pI of 8.2. The preprotein, consisting of 443 amino acids, was predicted to include a complement C1r/C1s, Uegf, and bone morphogenic protein-1 domain, a low-density lipoprotein receptor class A domain, and a catalytic domain. HlSP sequence analysis showed high similarity to serine proteinases reported from arthropods and vertebrate animal species. Two-dimensional immunoblot analysis revealed endogenous HlSP in adult tick extracts at 50 kDa. Endogenous HlSP was also expressed in all lifecycle stages of H. longicornis. Immunohistochemical studies detected the endogenous enzyme in the midgut epithelial cells of an adult tick. The Escherichia coli-expressed recombinant HlSP was demonstrated to degrade bovine serum albumin and hydrolyze the substrate Bz-L-Arg-pNA at the rate of 30.2 micromol/min/mg protein. Further, HlSP expression was up-regulated during a blood-feeding process, indicating its involvement in the digestion of host blood components.  相似文献   
49.
50.
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