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   211篇
  免费   12篇
林业   6篇
  9篇
综合类   37篇
农作物   4篇
水产渔业   3篇
畜牧兽医   159篇
园艺   2篇
植物保护   3篇
  2023年   2篇
  2021年   2篇
  2020年   1篇
  2019年   1篇
  2018年   4篇
  2017年   3篇
  2016年   4篇
  2015年   2篇
  2014年   4篇
  2013年   17篇
  2012年   9篇
  2011年   6篇
  2010年   14篇
  2009年   5篇
  2008年   7篇
  2007年   10篇
  2006年   3篇
  2005年   4篇
  2004年   1篇
  2003年   3篇
  2002年   4篇
  2001年   5篇
  2000年   2篇
  1999年   4篇
  1998年   13篇
  1997年   5篇
  1996年   10篇
  1995年   4篇
  1994年   4篇
  1993年   5篇
  1992年   10篇
  1991年   11篇
  1990年   6篇
  1989年   11篇
  1988年   9篇
  1987年   2篇
  1986年   2篇
  1985年   1篇
  1980年   2篇
  1975年   1篇
  1969年   1篇
  1968年   2篇
  1953年   1篇
  1949年   1篇
  1948年   1篇
  1947年   1篇
  1939年   1篇
  1934年   1篇
  1918年   1篇
排序方式: 共有223条查询结果,搜索用时 15 毫秒
61.
Previously, starch granules of maize (Zea mays), sorghum (Sorghum bicolor), and millet (Pennisetum americanum) were found to contain channels connecting the interior cavity with the outside surface, and the channels of maize starch channels were found to contain, presumably to be lined with, proteins. One objective of this study was to identify and characterize channel proteins of maize starch granules. A putative starch granule channel protein extract was subjected to 2D-PAGE. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry was used to identify the proteins. Data analysis indicated the presence of actin-like and tubulin-like (FtsZ) proteins, ADP-glucose pyrophosphorylase large and small subunits (Shrunken2 [Sh2] and Brittle2 [Bt2], respectively), granule-bound starch synthase (GBSS), and Brittle1 (Bt1, an adenylate translocator). A combination of Western blot analysis and immunolocalization confirmed the presence of an actin-like protein within the starch granule structure. Another objective was to determine the origin of maize starch granule channels. TEM examination of maize endosperm amyloplasts that did not contain a formed starch granule revealed structures that were connected to the amyloplast membrane and extended inward to the center of the plastid.  相似文献   
62.
Toxigenic strains of Pasteurella multocida were readily differentiated from non-toxigenic strains by an agarose overlay method using bovine turbinate cells or bovine lung cells. Cells which were young and densely confluent were best suited to this assay. The incubation period required to distinguish toxigenic strains was dependent on the confluence of the monolayers, which was affected by the seeding rate, cell passage level and growth time prior to overlay. The agarose overlay method correctly identified 11 of 11 reference strains of Pasteurella multocida, and visible cytotoxic changes were present in the monolayers after 48 to 65 h. Outbreaks of the enzootic form of atrophic rhinitis in 2 New South Wales piggeries were associated with the isolation of toxigenic type D strains of P. multocida.  相似文献   
63.
64.
Diseases of the reproductive tract are a frequent problem in dairy herds. Herpesviruses are uterine pathogens also involved in other clinical diseases; for example, bovine herpesvirus type 4 BoHV‐4 induces abortion, enteritis, metritis, pneumonia and vaginitis, but it can also be detected in healthy cows. The role of BoHV‐4 in the development of clinical endometritis (CE) or subclinical endometritis (SE) has not clearly been described. Therefore, the objective of this study was to describe the prevalence of uterine BoHV‐4 infection and its relationship with clinical, bacteriological and cytological findings in dairy cows 20–30 days after calving. The experiment was performed as a completely randomized block design, with farm (= 10) as blocking criterion and with cow (= 397) as the experimental unit. Logistic regression models were used to assess the effect of BoHV‐4 infection on CE, SE and reproductive performance. Proportion of cows infected with BoHV‐4 was 5.8% (= 23/397). BoHV‐4 was isolated in 11.0% (= 12/109), 4.8% (= 4/84) and 3.6% (= 7/194) of cows diagnosed as CE, SE or healthy, respectively. A logistic model revealed that BoHV‐4 infection showed a tendency to increase the risk for CE (AOR = 2.17; = .10) but significantly reduced both, the odds for artificial insemination within 80 days post‐partum (dpp) (AOR = 0.37; = .035) and for pregnancy within 200 dpp (AOR = 0.13; = .004). Furthermore, BoHV‐4 infection increased the chance for intrauterine infection with Trueperella pyogenes (AOR = 5.55; < .001) and vice versa (AOR = 5.79, < .001). In conclusion, BoHV‐4 infection is associated with reduced chances for insemination and pregnancy by 200 dpp and showed a trend to be associated with increased risk for CE. Furthermore, BoHV‐4 and Trueperella pyogenes infections are strongly related.  相似文献   
65.
Lidocaine patches have been used to provide local analgesia in dogs and cats. We conducted this study to assess the systemic and local absorption of lidocaine from topical patches in cats. Eight 2-year-old cats received either intravenous lidocaine at 2 mg/kg or one 700 mg lidocaine patch placed on the lateral thorax for 72 h, in a cross-over randomized repeated measures design. Plasma was collected at specific times and the skin was biopsied at the time of patch removal for the quantitative analysis of lidocaine and its major metabolite, monoethylglycinexylidide (MEGX), by gas chromatography with mass spectrometry. Percent absorption time plots for systemic lidocaine appearance were constructed using the Loo-Riegelman method. Approximately, constant rate absorption was observed from 12-72 h after patch application at a mean +/- SD rate of 109 +/- 49 microg/kg/h, resulting in steady-state lidocaine plasma concentrations of 0.083 +/- 0.032 microg/mL and MEGX concentrations of 0.012 +/- 0.009 microg/mL. Overall bioavailability of transdermal lidocaine was 6.3 +/- 2.7%, and only 56 +/- 29% of the total lidocaine dose delivered by the patch reached systemic circulation. Skin lidocaine concentrations were much higher than plasma concentrations, at 211 +/- 113 microg/g in the thoracic skin beneath the patch and 2.2 +/- 0.6 microg/g in the contralateral thoracic skin without the patch. As both lidocaine and MEGX were recovered from contralateral skin, it is likely that lidocaine accumulated in the skin from low systemic concentrations of circulating lidocaine over the 72-h period of patch application. Plasma lidocaine concentrations remained well below systemically toxic concentrations, and no obvious clinical side effects were observed in any of the cats. The low systemic absorption rate coupled with high local lidocaine concentrations on the skin support the safe use of lidocaine patches in cats.  相似文献   
66.
67.
A 17-year-old Norway-spruce stand at Mt. Kleiner Feldberg (Taunus) was investigated. The mineral soil was found to be in the aluminum buffer range (pH H2O = 3.5) but the fine and very fine roots of injured and uninjured trees were sufficiently supplied with Ca and Mg. Mg-deficiency, however, was observed in current-year needles where the contents were 30 % and 45 % below standard values in uninjured and injured trees, respectively. In injured trees the severe Mg-losses of current-year needles coincided with a 20 to 60 % loss of the activities of a number of enzymes involved in the carbohydrate metabolism and a significant reduction of the growth of current-year twigs.  相似文献   
68.
69.
70.
Objective To document an ovine disease attributed to the consumption of Lythrum hyssopifolia (lesser loosestrife). Procedures Historical and histological review of field and experimental cases. Results 1–20% mortality occurred in sheep flocks grazing paddocks where L. hyssopifolia was the predominant green vegetation. Well‐documented disease outbreaks occurred in summer on nine farms across Victoria between 1974 and 2002. Liver damage occurred in all nine outbreaks, with kidney damage in at least eight. Hepatocyte necrosis was usually zonal to midzonal (zone 2) in the liver samples from four farms and periacinar (zone 3) in those from three farms, but some livers showed only single‐cell necrosis. Multinucleate hepatocytes near necrotic areas were a feature in six cases. Proximal tubular epithelium appeared to be the primary renal target and brown granules were often present in renal tubules. Biochemical and histological evidence of liver and kidney damage was obtained from two sheep experimentally pen‐fed harvested L. hyssopifolia. Conclusion Chemicals in L. hyssopifolia are toxic to ovine hepatocytes and renal tubular epithelial cells.  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