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   1506篇
  免费   100篇
  国内免费   1篇
林业   94篇
农学   43篇
基础科学   4篇
  291篇
综合类   160篇
农作物   63篇
水产渔业   118篇
畜牧兽医   685篇
园艺   31篇
植物保护   118篇
  2023年   9篇
  2022年   8篇
  2021年   28篇
  2020年   52篇
  2019年   70篇
  2018年   43篇
  2017年   33篇
  2016年   44篇
  2015年   36篇
  2014年   54篇
  2013年   81篇
  2012年   88篇
  2011年   127篇
  2010年   63篇
  2009年   41篇
  2008年   100篇
  2007年   109篇
  2006年   108篇
  2005年   94篇
  2004年   89篇
  2003年   86篇
  2002年   70篇
  2001年   14篇
  2000年   12篇
  1999年   14篇
  1998年   11篇
  1997年   6篇
  1996年   12篇
  1995年   5篇
  1994年   8篇
  1993年   8篇
  1992年   3篇
  1991年   4篇
  1989年   5篇
  1987年   4篇
  1985年   4篇
  1984年   3篇
  1983年   5篇
  1982年   3篇
  1981年   8篇
  1980年   4篇
  1978年   4篇
  1973年   4篇
  1971年   2篇
  1970年   2篇
  1969年   2篇
  1968年   2篇
  1966年   2篇
  1960年   2篇
  1913年   2篇
排序方式: 共有1607条查询结果,搜索用时 781 毫秒
991.
We present two quantum calculations of the infrared spectrum of protonated methane (CH5+) using full-dimensional, ab initio-based potential energy and dipole moment surfaces. The calculated spectra compare well with a low-resolution experimental spectrum except below 1000 cm(-1), where the experimental spectrum shows no absorption. The present calculations find substantial absorption features below 1000 cm(-1), in qualitative agreement with earlier classical calculations of the spectrum. The major spectral bands are analyzed in terms of the molecular motions. Of particular interest is an intense feature at 200 cm(-1), which is due to an isomerization mode that connects two equivalent minima. Very recent high-resolution jet-cooled spectra in the CH stretch region (2825 to 3050 cm(-1)) are also reported, and assignments of the band origins are made, based on the present quantum calculations.  相似文献   
992.
A 13-year-old neutered female Labrador retriever had inspiratory dyspnea secondary to bilateral laryngeal paralysis. Radiographically, there was pectus excavatum with a mediastinal shift to the right. Arytenoid lateralization was performed, relieving the upper respiratory obstruction, and the sternal deformity also resolved. Chronic upper respiratory obstruction should be considered in dogs with pectus excavatum. Furthermore, correction of upper respiratory obstruction has the potential to result in resolution of pectus excavatum.  相似文献   
993.
In dogs with a congenital portosystemic shunt (CPSS), the outcome after CPSS attenuation is difficult to predict but is most likely related to hepatic and vascular proliferation that follows the attenuation. The aim of this study was to evaluate the prognostic value of shunt localization (extrahepatic vs. intrahepatic), plasma albumin concentration and hepatic mRNA expression of 19 genes involved in hepatic and vascular growth. The study population consisted of 48 dogs that were referred for surgical ligation of a single intrahepatic or extrahepatic CPSS. Gene expression was measured in intraoperatively sampled hepatic tissue with quantitative real-time PCR. Albumin, methionine adenosyltransferase 2α (MAT2α) and HGF activator (HGFac) were positively associated with complete recovery after CPSS attenuation using multivariate statistical analyses. Individual outcome could be correctly predicted in 83% of dogs using albumin, MAT2α and HGFac as high or low values compared to cut-off values of 19.5 g/L, 0.457 and 0.974, respectively. These variables predicted outcome after CPSS ligation better than shunt localization or albumin alone. Other evaluated gene products were not correlated with outcome.  相似文献   
994.
995.
996.
997.
998.
Veterinary Research Communications - Isolation and culture of distinct primary endometrial cells are key to reliable in-vitro models to investigate the uterine immune response and optimse new...  相似文献   
999.
1000.
A 10-year-old intact male Golden Retriever was presented to The Ohio State University Veterinary Medical Center for acute, non-painful facial swelling of the right mandibular region. On physical examination, the right mandibular swelling was found to represent marked lymphadenopathy of the submandibular lymph node. At this time, marked lymphadenopathy of the prescapular and popliteal lymph nodes was also appreciated. The CBC showed a moderate leukocytosis (38.4 × 109 cells/L, reference interval [RI] 4.8-13.9 × 109 cells/L) characterized by a moderate lymphocytosis (28.4 × 109 cells/L, RI 1.0-4.6 × 109 cells/L). Evaluation of peripheral blood and enlarged prescapular and popliteal lymph nodes revealed two morphologically different populations of homogeneous lymphocytes, with the lymphocyte population in the lymph nodes being distinct from that in the blood smear. Flow cytometry of peripheral blood revealed CD45-, CD5+, CD4-, CD8-, variably CD21+ neoplastic lymphocytes compatible with T-zone lymphocytes due to the absence of CD45 expression. Flow cytometry of the lymph node aspirate indicated a distinct population of CD21+ lymphocytes consistent with a B-cell phenotype along with a smaller proportion of the T-zone lymphocytes observed in the blood confirming the presence of two distinct populations of neoplastic lymphocytes, one involving T cells, and the other involving B 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