全文获取类型
收费全文 | 188407篇 |
免费 | 10360篇 |
国内免费 | 142篇 |
专业分类
林业 | 7481篇 |
农学 | 5807篇 |
基础科学 | 1226篇 |
23256篇 | |
综合类 | 32600篇 |
农作物 | 7380篇 |
水产渔业 | 9226篇 |
畜牧兽医 | 97113篇 |
园艺 | 2446篇 |
植物保护 | 12374篇 |
出版年
2019年 | 1764篇 |
2018年 | 2602篇 |
2017年 | 3022篇 |
2016年 | 2745篇 |
2015年 | 2308篇 |
2014年 | 2920篇 |
2013年 | 7349篇 |
2012年 | 5311篇 |
2011年 | 6727篇 |
2010年 | 4268篇 |
2009年 | 4469篇 |
2008年 | 6530篇 |
2007年 | 6166篇 |
2006年 | 5838篇 |
2005年 | 5378篇 |
2004年 | 5115篇 |
2003年 | 5242篇 |
2002年 | 4755篇 |
2001年 | 5778篇 |
2000年 | 5900篇 |
1999年 | 4668篇 |
1998年 | 1991篇 |
1997年 | 1940篇 |
1996年 | 1824篇 |
1995年 | 2204篇 |
1994年 | 1966篇 |
1993年 | 1833篇 |
1992年 | 3865篇 |
1991年 | 4049篇 |
1990年 | 3896篇 |
1989年 | 3892篇 |
1988年 | 3629篇 |
1987年 | 3652篇 |
1986年 | 3776篇 |
1985年 | 3642篇 |
1984年 | 2944篇 |
1983年 | 2610篇 |
1982年 | 1786篇 |
1979年 | 2750篇 |
1978年 | 2236篇 |
1977年 | 1864篇 |
1976年 | 1890篇 |
1975年 | 2006篇 |
1974年 | 2456篇 |
1973年 | 2484篇 |
1972年 | 2329篇 |
1971年 | 2177篇 |
1970年 | 2092篇 |
1969年 | 2025篇 |
1967年 | 1806篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
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
962.
A study of the interaction between bromocresol green dye and bovine,ovine and equine serum globulins
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
963.
Fulmer R Loeb WF Martin DP Gard EA 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》1984,13(1):19-25
The intravenous administration of 0.75 gm glucose per kg and the measurement of serum glucose pretest and at 10, 20, 30, 60, 90 and 120 minutes constitute a satisfactory protocol for intravenous glucose tolerance testing of Rhesus (Macaca mulatto) and African Green (Cercopithecus aethiops) monkeys. No significant differences were noted between animals restrained with ketamine hydrochloride and those restrained with sodium pentobarbital, but the African Green males and females and the male Rhesus monkeys yielded significantly different results while being manually restrained. 相似文献
964.
Hirsch VM Mitcham SC Dunn DK 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》1984,13(2):16-20
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
965.
Pulmonic stenosis is caused by a malformed pulmonic valve, stricture of the right ventricular outflow tract or stricture of the pulmonary artery. English Bulldogs, Beagles, Samoyeds, Fox Terriers and Chihuahuas are predisposed. Clinical signs in severely affected dogs include exercise intolerance, stunting, dyspnea, syncope and ascites. Auscultation reveals a high-frequency, crescendo-decrescendo murmur during systole, loudest over the left side of the thorax, near the sternal cardiac border. An ECG may reveal a right-axis deviation of greater than 120 degrees, S waves in leads I, II and III, deep S waves in CV6LL, CV6LU and V10, Q waves deeper than 0.5 mv in leads II, III and AVF, and positive T waves in lead V10. Plain film LAT thoracic radiographs reveal an elevated carina, increased sternal contact of the heart, loss of the cranial cardiac waist and a widened cardiac silhouette, with normal pulmonary vasculature. A DV projection reveals an inverted "D" shape of the right ventricle and a pulmonary artery bulge. A nonselective angiocardiogram reveals poststenotic dilation of the main pulmonary artery. Treatment involves surgical correction of the stenosis. 相似文献
966.
Factors affecting somatic cell counts and the association between somatic cell counts and milk production were evaluated. Data were collected from 748 Ontario Dairy Herd Improvement Corporation supervised herds that were on production and somatic cell count programs between April 1981 and March 1983. Two data files were created; one, the lactation summary file, contained one record per cow on each of 9406 Holsteins and the other, the test day file, included results of all tests during the complete lactation on each of the above cows. The latter file contained 85,236 records. Multiple curvilinear least squares regression was used to create five separate models. The dependent variables used in the models were natural logarithms (Loge) of the geometric mean of the somatic cell count for the lactation, 305 day milk production and breed class average for milk from the lactation summary file, and loge of the 24 hour somatic cell count and 24 hour milk production from the test day file. The somatic cell count at both the lactation and test day level increased with age up to approximately ten years and thereafter slowly decreased. The variable "days in milk" was not significantly associated with the lactation average somatic cell count. A curvilinear relationship was found between days in lactation at the time of test and the somatic cell count of 24 hour milk production. The somatic cell count increased until approximately 250 days in lactation and thereafter slowly decreased. It was found that the highest cell counts occurred in summer and the lowest in winter.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
967.
Gingerich PD 《Science (New York, N.Y.)》1984,226(4677):994-996
968.
Dickson D 《Science (New York, N.Y.)》1984,226(4678):1059
969.
970.