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   237960篇
  免费   14477篇
  国内免费   651篇
林业   23439篇
农学   14038篇
基础科学   2961篇
  41824篇
综合类   17111篇
农作物   17086篇
水产渔业   16599篇
畜牧兽医   90342篇
园艺   6274篇
植物保护   23414篇
  2021年   2443篇
  2020年   2851篇
  2019年   3656篇
  2018年   3929篇
  2017年   4239篇
  2016年   4726篇
  2015年   4301篇
  2014年   5641篇
  2013年   16279篇
  2012年   5978篇
  2011年   7846篇
  2010年   7284篇
  2009年   7816篇
  2008年   7194篇
  2007年   6284篇
  2006年   6991篇
  2005年   6176篇
  2004年   6038篇
  2003年   5760篇
  2002年   5131篇
  2001年   5688篇
  2000年   5280篇
  1999年   5029篇
  1998年   4096篇
  1997年   4136篇
  1996年   3884篇
  1995年   4404篇
  1994年   3790篇
  1993年   3522篇
  1992年   3967篇
  1991年   4233篇
  1990年   3924篇
  1989年   3854篇
  1988年   3407篇
  1987年   3459篇
  1986年   3258篇
  1985年   3620篇
  1984年   3438篇
  1983年   3206篇
  1982年   2725篇
  1981年   2650篇
  1980年   2610篇
  1979年   2934篇
  1978年   2636篇
  1977年   2454篇
  1976年   2320篇
  1975年   2135篇
  1974年   2238篇
  1973年   2184篇
  1972年   1928篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The pharmacokinetics of fenbendazole and oxfendazole in cattle are described. The pharmacokinetics of oxfendazole were not significantly different when administered orally and by intra-ruminal injection. At a dose rate of 4.5 mg/kg, administered orally, fenbendazole gave rise to mean peak concentrations in plasma of fenbendazole and oxfendazole of 0.11 and 0.13 g/ml respectively. Oral administration of oxfendazole, at 4.5 mg/kg body weight, gave rise to plasma peak concentrations of fenbendazole and oxfendazole of 0.10 and 0.20 g/ml respectively. Following intra-ruminal administration of oxfendazole, the peak concentrations were 0.11 and 0.18 g/ml respectively.  相似文献   
992.
In human medicine it has been shown that the bromocresol green (BCG) dye-binding method for the determination of serum albumin is not entirely specific, the dye reacting also with certain human serum globulins. This causes over-estimation of albumin when reaction times are prolonged beyond 30 seconds.In the present study, serum albumin values obtained from three animal species by the immediate, i.e. less than 30 seconds, BCG reaction were compared with those by the 10-minute BCG reaction. Albumin-depleted sera were prepared using an affinity chromatography technique and their reactions and those of purified gamma globulin preparations with the dye were studied.In cattle, sheep and horses, serum albumin values obtained by the 10-minute reaction were higher than those obtained by the immediate BCG reaction, the differences being statistically significant. Purified gamma globulin did not react with the BCG dye after 10 minutes, but other globulins did. There were differences between the species in the magnitude of the reaction of their globulins with BCG dye.  相似文献   
993.
An unusual combination of blood cytopenias and monocytic proliferation was observed in a dog. Initial hematologic findings included severe thrombocytopenia, neutropenia, mild nonregenerative anemia and apparently normal bone marrow. Subsequently, a severe persistent monocytosis developed and the bone marrow became populated with monocytes and cytophagic macrophages. Splenomegaly was due to reticuloendothelial hyperplasia and extramedultary hematopoiesis. Treatment consisted of splenectomy and azathioprine but the response was poor and the dog was euthanized. Postmortem examination revealed a hypocellular bone marrow which contained moderate numbers of monocytes and plasma cells. Neoplastic proliferation was absent in visceral organs. No definite diagnosis was established; chronic blood cell consumption, perhaps immune-mediated, may have been responsible for the extensive reticuloendothelial hyperplasia and cytophagia.  相似文献   
994.
The cleistogamous species Collomia grandiflora produces dimorphic cross-incompatible flowers on a single plant. The open or chasmogamous flower has smaller, flask-shaped stigmatic papillae, larger pollen grains, longer styles, and faster pollen tube growth rates down the style than the closed or cleistogamous flower. In intermorph crosses, pollen tube growth rates are greatly decreased and fertilization does not occur.  相似文献   
995.
996.
997.
998.
999.
1. It has been shown that both the variety of wheat and the environment under which growth took place influenced the quantities of starch and cell wall carbohydrate contents of wheat.

2. The different varieties of wheat investigated contained different proportions of water‐soluble to water‐insoluble hemicelluloses.

3. By comparison of the arabinose to xylose ratios it was concluded that water‐soluble and insoluble arabinoxylans of wheat were branched to the same degree.

4. Starch from six wheat varieties grown in the U.K. was very well digested by adult cockerels and true metabolisable energy values of the wheats were high.

5. Small amounts of cell wall carbohydrates were digested by adult cockerels.  相似文献   

1000.
1. Conditions affecting the keeping quality of traditional farm‐fresh turkeys were investigated.

2. Storage of uneviscerated Wrolstad turkeys at 4 °C for 10 days caused no statistically significant changes in meat flavour or texture.

3. During further storage at —2 °C, however, there was a slight but significant change in flavour, which became more marked with time in birds which had been eviscerated after the initial period at 4 °C.

4. Both eviscerated and uneviscerated birds became slightly tougher during storage.

5. Initial holding at 4 °C increased the numbers of psychrotrophic bacteria on the skin by about 103 but subsequent changes at — 2 °C were slight for uneviscerated birds.

6. Eviscerated carcases had higher counts than uneviscerated birds after storage at — 2 °C and, although ‘off’ odours were not detected, spoilage appeared to be imminent at the end of the 20‐d period.  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