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   276篇
  免费   12篇
林业   37篇
农学   7篇
  44篇
综合类   8篇
农作物   10篇
水产渔业   23篇
畜牧兽医   147篇
园艺   1篇
植物保护   11篇
  2022年   5篇
  2021年   9篇
  2020年   3篇
  2019年   4篇
  2018年   7篇
  2017年   1篇
  2016年   16篇
  2015年   10篇
  2014年   10篇
  2013年   19篇
  2012年   16篇
  2011年   19篇
  2010年   15篇
  2009年   8篇
  2008年   15篇
  2007年   16篇
  2006年   11篇
  2005年   19篇
  2004年   14篇
  2003年   8篇
  2002年   14篇
  2000年   6篇
  1999年   6篇
  1998年   3篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1993年   1篇
  1992年   3篇
  1991年   1篇
  1990年   3篇
  1989年   4篇
  1988年   11篇
  1987年   2篇
  1986年   3篇
  1966年   1篇
  1925年   1篇
排序方式: 共有288条查询结果,搜索用时 15 毫秒
101.
Effects of ligation of the ductus deferens on the fowl epididymal region   总被引:1,自引:0,他引:1  
The effects of ligation of the ductus deferens on the epididymis in the fowl were studied histochemically and immunohistochemically to reveal the mechanisms of sperm disposal. At one week post-ligation, the lumina of the rete testes (RT) and the efferent ductules (ED) were distended and filled with densely accumulated spermatozoa. Macrophages and foreign-body giant cells were aggregated in and around the accumulations. The epithelium regressed in the initial portion of the RT with the invasion of fibroblasts and heterophiles into the lumen. The other part of the epithelium was penetrated by many spermatozoa. Numerous lymphocytes and plasma cells infiltrated into the interstitium. At 4 weeks, larger number of spermatozoa agglutinated in the lumen, and large masses of foamy cells and proliferated connective tissue protruded into the lumen. At 8 weeks, large masses of foamy cells were noted. The connecting ductules or the epididymal duct showed no marked changes after ligation. The epithelium of the ED showed weaker or no acid phosphatase activity after ligation. Immunoglobulin G-containing cells increased in number in the interstitium. These results showed that ligation of the ductus deferens in the fowl causes granuloma in the RT and ED, and that epithelial cells, macrophages and granuloma are engaged in the removal of spermatozoa. The participation of antibody is suggested in the sperm disposal processes.  相似文献   
102.
103.
Anti-copper treatments have been investigated to determine whether they suppress angiogenesis and tumor development since Cu is widely accepted as being required for angiogenesis. We examined the effects of treatment with trientine, a copper-chelating agent, on tumor development in a murine xenograft model using fibrosarcoma-derived transplantable QRsp-11 cells and C57BL/6 mice and induction of apoptosis in tumor cells and endothelial cells in vivo and in vitro. The tumor volumes increased more slowly in trientine-treated mice than in untreated mice. Tumor volumes in the treated mice were significantly smaller than those in the untreated mice at 24 days postinoculation (d.p.i.) of tumor cells. A cluster of pyknotic tumor cells and morphological abnormalities in capillary endothelial cells were observed in the tumors of trientine-treated mice but not in the tumors of untreated mice. The proportions of apoptotic and necrotic cells in the tumors of treated mice were approximately 3.5-fold higher than those in the tumors of untreated mice at 14 d.p.i. When the cells were treated with trientine in vitro, mouse endothelial cells and bovine primary endothelial cells showed an approximately 10-fold higher sensitivity to trientine than QRsp-11 cells in terms of D37. However, the proportion of apoptotic cells in endothelial cells was significantly lower than that in QRsp-11 cells after treatment with trientine. These results show that apoptosis was induced in tumor cells by treatment with trientine in vivo and in vitro.  相似文献   
104.
A ten-year-old Shetland pony gelding showed low appetite, ataxia, peculiar swaying, clouding of consciousness, and ultimately died. At necropsy, multiple coalescing granulomatous foci were detected in the kidneys, and small necrotic lesions were found in the cerebellum. Histologic examination of the renal tissue sections revealed extensive granuloma, and Halicephalobus gingivalis-like nematodes were seen. Similar nematodes were found in the granulomatous or necrotic lesions of the renal lymph nodes and cerebellum, and were also frequently detected in cerebrospinal meningovascular lesions. Morphologic features together with partial ribosomal RNA gene sequences of the nematodes in the lesions revealed that they were H. gingivalis. The present results indicated that H. gingivalis caused granulomatous nephritis and meningoencephalomyelitis in this pony gelding.  相似文献   
105.
Selection of bovine cumulus-oocyte complexes (COCs) for in vitro embryo production (IVP) is generally based on the morphological characteristics of the cumulus cells surrounding the oocytes and the ooplasm under microscopic observation. The purpose of this study was to examine a simple method for selection of COCs by sedimentation with Percoll solutions. COCs were aspirated from ovaries derived from a local slaughterhouse, and the COCs were classified by the morphology of their cumulus cell layers, as follows: Class A, compact and thick; Class B, compact but thin; Class C, partially denuded and thin; and Class D, denuded. Percoll solutions were prepared by diluting Percoll to 7.5, 10, 12.5, 15, 17.5, 20, 22.5, 25, 27.5 and 30% solutions, respectively. COCs were placed on the surface of the Percoll solution for 3 min, and the precipitated COCs were transferred to stepwise high density solution. The percentage of Percoll solution just before buoyancy was considered to the specific sedimentary value of the COC and oocyte. The mean sedimentary value of Class A COCs was higher than those of the other classes (P<0.01). The mean sedimentary values of denuded oocytes from Classes A and B were higher than those from Classes C and D (P<0.01). Our results show that sedimentation of COCs and denuded oocytes was generally related to the morphological quality of the COCs, although the sedimentary values ranged widely for one class of COCs and oocytes. The Percoll method can be used for simple selection of COCs.  相似文献   
106.
A trypanosome was isolated from a sika deer (Cervus nippon yesoensis) in Hokkaido, Japan, during the primary culture of sika deer renal cells. This is the first report of isolation of a Megatrypanum trypanosome from Japanese Cervidae. The trypanosome, designated TSD1, was propagated and maintained in Eagle's modified essential medium containing 20% fetal bovine serum with sika deer renal cells as feeder. The TSD1 trypanosome was morphometrically similar to Trypanosoma cervi, which is commonly isolated from American and European deer. PCR analysis with primers for 18S ribosomal DNA and nucleotide sequencing showed that TSD1 is a member of genus Trypanosoma, subgenus Megatrypanum. Phylogenetically TSD1 is closely related to T. theileri, a common trypanosome of cattle, but is distinguishable from T. theileri by some morphometrical and biological features.  相似文献   
107.
Selection for high (H) and low (L) oxygen consumption (OC) as an indirect estimation of maintenance energy requirement was determined. Feed intake and body weight were measured and feed conversion ratio (FCR) of 4–8‐week‐old mice was calculated. Respiratory activity of hepatic mitochondria was measured at 12 weeks. Total feed intake (H: 103.74 g, L: 97.92 g, P < 0.01), daily feed intake (H: 3.70 g/day, L: 3.50 g/day, P < 0.01) and FCR (H: 18.79, L: 15.50, P < 0.01) were significantly different between lines. The line by sex interaction was significant for FCR. No line differences were observed in males; and the FCR of the H line was greater than in the L line in females. H line mice had the highest hepatic mitochondrial respiratory activity in state 2 (P < 0.01), the highest uncoupled respiratory rate of mitochondria in the presence of an uncoupling agent (P < 0.001), and the mitochondrial proton leak. The adenosine diphosphate/ O ratio was highest in the L line (P < 0.05). This suggests that the selection for high and low OC induced differences in basal mitochondrial respiration and basal metabolism, resulting in difference in FCR between H and L lines.  相似文献   
108.
In this study, we examined the effects of a dextran-modified silk fibroin nanofibrous mat (D-SFNM) on wound healing. To increase the hydrophilicity of silk fibroin (SF), the SF nanofibrous mat (SFNM) was modified with oxidized dextran. The D-SFNM absorbed water faster than the SFNM, and the swelling ratio was increased by approximately 80 % compared with the SFNM. An in vitro cell (NIH3T3) test revealed that fewer cells attached to the D-SFNM than the SFNM, but the proliferation of cells was not significantly affected by the presence of dextran. An in vivo wound healing test with mice indicated that the D-SFNM resulted in a good wound recovery effect similar to a commercial wound dressing material. The increased hydrophilicity of the D-SFNM might balance the moist environment at the wound site, which improves the wound healing compared with the SFNM.  相似文献   
109.
Three-week iron (Fe) deficiency stress experiments were conducted using two citrus root stocks, Fe-deficiency tolerant Orange Jasmine (OJ, Murraya exotica L.) and the sensitive Flying Dragon [FD, Poncirus trifoliata var. monstrosa (T. Ito) Swingle]. Root ferric chelate reductase activity and proton extrusion increased in OJ between 12 and 18 d of stress, whereas there was no change in FD. Dry weight of OJ roots increased in contrast to FD which decreased. The Mn content in OJ remained the same even under Fe stress. Zn content in OJ roots doubled while that of FD increased 4-folds. The shoot/root Fe accumulation ratio increased in OJ while it decreased in FD. OJ apparently has mechanisms for increasing root biomass, controlling Fe reutilization and regulating manganese (Mn) and zinc (Zn) absorption in response to Fe deficiency. These mechanisms could help maintain homeostasis under heavy metal stress, which would be useful for improved growth of economically important citrus species.  相似文献   
110.
Multigenic glutelins and monogenic globulin are major storage proteins accumulating in vacuole-derived protein body (PB-II) of rice (Oryza sativa L.) seeds. Because their interplay in PB-II formation was scarcely known, the effect of globulin-less mutation on glutelin accumulation was investigated. In globulin-less mutants, no phenotypic defect was found in seed and plant growth, while PB-II was deformed and apparent glutelin composition was changed, producing new glutelin α polypeptides X1–X5. 2D-PAGE of different combinations of globulin-less and glutelin subunit mutations suggested that the X1/X2, X3, and X4/X5 were derived from glutelin GluB1/GluB2/GluB4, GluA3, and GluA1/GluA2 subunits, respectively. Western blot with glutelin GluB4 subunit-specific and its variable region discriminable antibodies indicated at least in part the new spots X1/X2 are partially degraded products of GluB4 α polypeptides by the removal of 2–39 residues from C-terminus. Time course experiments with maturing seeds indicated the partial degradation of GluB4 occurred earlier (from 7 days after flowering) and higher than that of GluA1/GluA2. Considering the above results together with the fact that globulin accumulates at the periphery of PB-II and its absence produces deformed PB-II, globulin protects glutelins from proteinase digestion and thereby facilitates stable glutelin accumulation.  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