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   1053篇
  免费   53篇
  国内免费   1篇
  2023年   13篇
  2022年   12篇
  2021年   33篇
  2020年   18篇
  2019年   26篇
  2018年   30篇
  2017年   30篇
  2016年   35篇
  2015年   52篇
  2014年   49篇
  2013年   79篇
  2012年   77篇
  2011年   73篇
  2010年   50篇
  2009年   41篇
  2008年   53篇
  2007年   46篇
  2006年   39篇
  2005年   38篇
  2004年   30篇
  2003年   25篇
  2002年   18篇
  2001年   21篇
  2000年   15篇
  1999年   17篇
  1998年   6篇
  1997年   4篇
  1996年   5篇
  1995年   8篇
  1994年   8篇
  1993年   7篇
  1992年   16篇
  1991年   14篇
  1990年   12篇
  1989年   16篇
  1988年   6篇
  1987年   10篇
  1986年   4篇
  1985年   10篇
  1984年   6篇
  1983年   4篇
  1982年   4篇
  1981年   5篇
  1979年   7篇
  1978年   3篇
  1977年   7篇
  1975年   5篇
  1971年   2篇
  1970年   2篇
  1966年   3篇
排序方式: 共有1107条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
45.
46.
A study was conducted to determine the efficacy of β-mannanase supplementation to a diet based on corn and soya bean meal (SBM) on growth performance, nutrient digestibility, blood urea nitrogen (BUN), faecal coliforms and lactic acid bacteria, and noxious gas emission in growing pigs. A total of 140 pigs [(Landrace × Yorkshire) × Duroc; average body weight 25 ± 3 kg] were randomly allotted to a 2 × 2 factorial arrangement with dietary treatments consisting of hulled or dehulled SBM without or with supplementation of 400 U β-mannanase/kg. During the 6 weeks of experimental feeding, β-mannanase supplementation had no effect on body weight gain, feed intake and gain:feed (G:F) ratio. Compared with dehulled SBM, feeding hulled SBM caused an increased feed intake of pigs in the entire trial (p = 0.05). The G:F ratio was improved in pigs receiving dehulled SBM (p < 0.05). Dietary treatments did not influence the total tract digestibility of dry matter, nitrogen and gross energy. Enzyme supplementation reduced (p < 0.05) the population of faecal coliforms and tended to reduce the NH3 concentration after 24 h of fermentation in a closed box containing faecal slurry. Feeding hulled SBM tended to reduce NH3 emission on days 3 and 5 of fermentation. In conclusion, mannanase supplementation had no influence on growth performance and nutrient digestibility but showed a positive effect on reducing coliform population and tended to reduce NH3 emission. Dehulled SBM increased G:F ratio and hulled SBM tended to reduce NH3 emission.  相似文献   
47.
Substance P, acting via its neurokinin 1 receptor (NK1 R), plays an important role in mediating a variety of inflammatory processes. Its interaction with chemokines is known to play a crucial role in the pathogenesis of acute pancreatitis. In pancreatic acinar cells, substance P stimulates the release of NFκB-driven chemokines. However, the signal transduction pathways by which substance P-NK1 R interaction induces chemokine production are still unclear. To that end, we went on to examine the participation of mitogen-activated protein kinases (MAPKs) in substance P-induced synthesis of pro-inflammatory chemokines, monocyte chemoanractant protein-1 (MCP-I), macrophage inflammatory protein-lα (MIP-lα) and macrophage inflammatory protein-2 (MIP-2), in pancreatic acini. In this study, we observed a time-dependent activation of ERK1/2, c-Jun N-terminal kinase (JNK), NFκB and activator protein-1 (AP-1) when pancreatic acini were stimulated with substance P. Moreover, substance P-induced ERK 1/2, JNK, NFκB and AP-1 activation as well as chemokine synthesis were blocked by pre-treatment with either extracellular signal-regulated protein kinase kinase 1 (MEK1) inhibitor or JNK inhibitor. In addition, substance P-induced activation of ERK 112, JNK, NFκB and AP-1-driven chemokine production were attenuated by CP96345, a selective NK1 R antagonist, in pancreatic acinar cells. Taken together, these results suggest that substance P-NK1 R induced chemokine production depends on the activation of MAPKs-mediated NFκB and AP-1 signalling pathways in mouse pancreatic acini.  相似文献   
48.
Despite ample literature on the toxic impact of lead on the environment and health, the exact mechanism of pathogenesis/toxicity is not clearly known. Because it is well established that lead induces oxidative stress, it is assumed that exposure to antioxidants may reduce the toxic impact of lead. In this study, we evaluated the impact of coadministration of the methanolic root extract of a plant Abutilon indicum (50, 100, 200 mg kg −1b.wt.) in mitigating the toxic impact of lead on the reproductive system of rats. In brief, Wistar rats were exposed to lead acetate in drinking water with or without coadministration of plant root extract and compared with that of control animals. After 45 days of exposure as outlined above, the animals were killed and the reproductive toxicity was assessed by sperm parameters, hormone and antioxidant enzyme assays, and testis histopathology. Significant reduction in testis weight, sperm count, testosterone levels, and antioxidant enzymes levels such as Superoxide Dismutase, Catalase, and Glutathione peroxidase was seen in lead-treated animals, confirming the toxic impact. The coadministration of A. Indicum (100 and 200 mg kg −1b.wt.) was found to bring the studied parameters close to the levels seen in untreated (control) animals. Our findings are indicative of the protective nature of A. Indicum against lead-induced reproductive toxicity in a dose-dependent manner. However, further characterization of the root extract is required to elucidate the probable mechanism of protection.  相似文献   
49.
Modulatory effect of quercetin on azathioprine induced toxic changes was studied in spleen of experimental animals. Azathioprine treatment caused an increase in serum albumin/globin ratio and a decrease in total protein in spleen tissue. An increase in a membrane bound ATPases was also noted. Supplementation of quercetin with azathioprine increased the protein content and lowered the activities of membrane ATPase in spleen. There was a decrease in serum albumin globulin ratio. It was concluded that quercetin modulated the protein and membrane bound ATPase activities and protected the spleen from azathioprine induced membrane damage.  相似文献   
50.
ProSAAS is a newly discovered protein with a neuroendocrine distribution generally similar to that of prohormone convertase 1 (PC1), a peptide-processing endopeptidase. Several proSAAS-derived peptides were previously identified in the brain and pituitary of the Cpe(fat)/Cpe(fat) mouse based on the accumulation of C-terminally extended peptides due to the absence of enzymatically active carboxypeptidase E, a peptide-processing exopeptidase. In the present study, antisera against different regions of proSAAS were used to develop radioimmunoassays and examine the processing profile of proSAAS in wild type and Cpe(fat)/Cpe(fat) mouse tissues following gel filtration and reverse phase high performance liquid chromatography. In wild type mouse brain and pituitary, the majority of proSAAS is processed into smaller peptides. These proSAAS-derived peptides elute from the reverse-phase column in the same positions as synthetic peptides that correspond to little SAAS, PEN, and big LEN. Mass spectrometry revealed the presence of peptides with the expected molecular masses of little SAAS and big LEN in the fractions containing immunoreactive peptides. The processing of proSAAS is slightly impaired in Cpe(fat)/Cpe(fat) mice, relative to wild-type mice, leading to the accumulation of partially processed peptides. One of these peptides, the C-terminally extended form of PEN, is known to inhibit PC1 activity and this could account for the reduction in enzymatically active PC1 seen in Cpe(fat)/Cpe(fat) mice. The observation that little SAAS and big LEN are the major forms of these peptides produced in mouse brain and pituitary raises the possibility that these peptides function as neurotransmitters or hormones.  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