全文获取类型
收费全文 | 6812篇 |
免费 | 286篇 |
国内免费 | 8篇 |
专业分类
林业 | 238篇 |
农学 | 350篇 |
基础科学 | 82篇 |
870篇 | |
综合类 | 362篇 |
农作物 | 254篇 |
水产渔业 | 207篇 |
畜牧兽医 | 3753篇 |
园艺 | 110篇 |
植物保护 | 880篇 |
出版年
2023年 | 30篇 |
2022年 | 44篇 |
2021年 | 62篇 |
2020年 | 85篇 |
2019年 | 91篇 |
2018年 | 110篇 |
2017年 | 103篇 |
2016年 | 117篇 |
2015年 | 94篇 |
2014年 | 132篇 |
2013年 | 501篇 |
2012年 | 311篇 |
2011年 | 355篇 |
2010年 | 178篇 |
2009年 | 184篇 |
2008年 | 339篇 |
2007年 | 330篇 |
2006年 | 281篇 |
2005年 | 284篇 |
2004年 | 293篇 |
2003年 | 258篇 |
2002年 | 258篇 |
2001年 | 234篇 |
2000年 | 215篇 |
1999年 | 195篇 |
1998年 | 54篇 |
1997年 | 53篇 |
1996年 | 56篇 |
1995年 | 63篇 |
1994年 | 40篇 |
1993年 | 46篇 |
1992年 | 105篇 |
1991年 | 117篇 |
1990年 | 133篇 |
1989年 | 109篇 |
1988年 | 102篇 |
1987年 | 84篇 |
1986年 | 67篇 |
1985年 | 71篇 |
1984年 | 66篇 |
1983年 | 45篇 |
1982年 | 30篇 |
1981年 | 41篇 |
1980年 | 44篇 |
1979年 | 45篇 |
1975年 | 26篇 |
1974年 | 25篇 |
1973年 | 26篇 |
1972年 | 35篇 |
1971年 | 32篇 |
排序方式: 共有7106条查询结果,搜索用时 10 毫秒
51.
A.M.B. Veldhuis I.M.G.A. Santman-Berends J.M. Gethmann M.H. Mars L. van Wuyckhuise P. Vellema M. Holsteg D. Höreth-Böntgen F.J. Conraths G. van Schaik 《Preventive veterinary medicine》2014
Schmallenberg virus (SBV), a novel orthobunyavirus that rapidly spread throughout north-western Europe in 2011, caused congenital malformations in lambs and goat kids (Van den Brom et al., 2012) and newborn calves (Hoffmann et al., 2012). The impact of the SBV epidemic seemed limited however, in terms of the number of affected herds with malformed offspring (European Food Safety Authority, 2012b). Nevertheless, little is known with regard to the overall within-herd impact of SBV infection. The objective of the current study was to quantify the impact of the 2011 SBV epidemic on the productivity of dairy cattle in the Netherlands and the district of Kleve, Germany. 相似文献
52.
Epithelial response to experimentally introduced intraluminal bacteria in the avian epididymal ducts
The response of the epithelial cells of the various ducts of the avian epididymis, whose function is poorly understood, to intraluminal bacteria was evaluated by the injection of an avirulent strain of Salmonella gallinarium into the RT for 24 h. Ultrastructurally, bacteria and invading mononuclear cells were present in the lumina of the RT, proximal efferent ducts (PED) and distal efferent ducts. However, only the non-ciliated (Type I) cells of the PED epithelium ingested bacteria from the lumen. Fragments of bacteria also occurred in several intercellular spaces in the epithelium of the PED. Some mononuclear cells also contained fragments of bacteria. Neither cell death in the various epithelia nor mononuclear infiltration of the periductal tissue occurred. Therefore, in addition to the established function of absorbing most of the testicular fluid entering the epididymis, the Type I cells also appear capable of recognising and removing foreign particulate matter from the epididymal through-flow in the proximal part of the epididymis. 相似文献
53.
54.
Hormonal responses to acute exercise, training and overtraining. A review with emphasis on the horse 总被引:1,自引:0,他引:1
de Graaf-Roelfsema E Keizer HA van Breda E Wijnberg ID van der Kolk JH 《The Veterinary quarterly》2007,29(3):82-101
Overtraining is an imbalance between training and recovery leading to symptoms associated with a neuroendocrine dysbalance called the overtraining syndrome, a disease characterized by behavioral, emotional and physical symptoms similar with depression. Although the prevalence of overtraining is high in human and equine athletes, at present no sensitive and specific test is available to prevent or diagnose overtraining. Nowadays, it is believed that combination of different (hormonal) parameters appear to be the best indicators of overtraining. Therefore, this review provides a summary of previous literature examining the response of the hypothalamic-pituitary-adrenal (HPA) axis and the growth hormone-insulin-like growth factor-I (GH-IGF-I) axis to acute and chronic exercise as well as overtraining in humans and horses. The exercise induced hormonal responses seem to be equal for the equine as well as the human athlete, which makes comparisons possible. Repeated bouts of exercise are suggested to provide a way to detect subtle changes in hormonal responses in the individual athlete, which may make them an important tool in detecting early overtraining. This should be combined with corticotropin releasing hormone (CRH) stimulation tests and basal ACTH and GH pulsatility determination. Further research is needed to establish the correct training intensity and rest period for the exercise test in equines. 相似文献
55.
Dilini N. Thilakaratne Monique N. Mayer Valerie S. MacDonald Marion L. Jackson Brenda R. Trask Beverly A. Kidney 《The Canadian veterinary journal. La revue veterinaire canadienne》2010,51(1):79-84
Polymerase chain reaction (PCR) assays for the immunoglobulin and T-cell receptor genes were utilized to determine phenotype and clonality from lymph node cytologic smears and peripheral blood lymphocytes from 10 dogs with lymphoma, before chemotherapy and during remission. Results were compared with those from 13 dogs with a cytologic diagnosis of lymph node hyperplasia. Clonality was identified in 7 of the lymphomas on the basis of either lymph node cytology or peripheral blood lymphocytes before treatment. No lymph node hyperplasia samples were clonal. In 6 of the dogs with lymphoma, clonality was demonstrated during clinical remission. Detection of PCR clonality during clinical remission is an effective means of identifying minimal residual disease in canine lymphoma and thus additional work is warranted to determine if molecular remission is prognostic or predictive for outcome in well-controlled and well-defined lymphoma subtypes. 相似文献
56.
Instructions on how to debone and stuff a turkey are available, but what is the best way to close it up? A randomised trial involving 15 turkeys was performed in order to evaluate skin disruption scores and cosmetic outcomes following the use of different suture patterns. Turkeys were deboned, stuffed and cooked according to guidelines of the US Department of Agriculture Food Safety and Inspection Services. After stuffing, they were randomly assigned to one of five closure groups: simple continuous Lembert; simple continuous Cushing; simple continuous Utrecht; simple continuous; or staples. Turkeys were cooked at 180 °C for two hours ensuring core temperature reached 75 °C. Suture line integrity was evaluated after removal of the sutures and the cosmetic aspect was graded. Before cooking, the Utrecht pattern and skin staples offered the best cosmetic result. After removal of the sutures, the skin remained intact only in the stapled group. All other suture patterns disrupted the skin after removal of the sutures, rendering the turkey less cosmetically appealing for serving. Closure of a stuffed turkey was best performed using skin staples to achieve the best cosmetic results. Using this technique you will be able to impress family and friends at a Christmas dinner, and finally show them your surgical skills. 相似文献
57.
A two-month-old female Tibetan terrier was re-presented with an incomplete closure of the patent ductus arteriosus. Following a second attempt to close the shunt by coil embolisation, arterial embolisation occurred. The successful removal of the embolised coil is described. 相似文献
58.
59.
The effect of clenbuterol on the incidence of abomasal lesions in veal calves was studied in two fattening units. Some of the calves in each unit were treated with 1.6 micrograms clenbuterol/kg bodyweight/day from the seventh until the 23rd week of the fattening period. In one unit the calves were fed milk replacer only and 176 of the 236 calves were treated with clenbuterol. In the other unit the calves were fed roughage pellets in addition to milk replacer and 92 of the 194 calves were treated with clenbuterol. Only in the second unit did the calves treated with clenbuterol have significantly fewer abomasal lesions. 相似文献
60.
J. Kirpensteijn R.J. Maarschalkerweerd I. van der Gaag H.S. Kooistra F.J. van Sluijs 《The Veterinary quarterly》2013,33(2):67-70
Summary The macroscopic and histological appearance of jejunal antimesenteric incisions approximated with two different absorbable suture materials (monofilament versus multifilament) and three closure techniques (appositional single layer, crushing single layer, and double layer) were compared in healthy dogs at 14 or 28 days, postoperatively. No significant differences between the two suture materials were observed for most of the macroscopic or histological variables. However, the monofilament suture material caused significantly more fibrous tissue reaction in the muscular layer of the jejunum than did the multifilament suture material. Of the three enterotomy closure techniques used in this study, the appositional single‐layer method proved to be the best. The double‐layer closure method caused a significant decrease in the incisional circumference, the relative circumference, and volume of the jejunum, and a significant increase in jejunal wall thickness. Our findings suggest that canine jejunal enterotomy incisions can be closed using an appositional suture pattern with relatively rapidly absorbable monofilament suture material. The use of double‐layer suture patterns for closure of jejunal enterotomy incisions should be avoided because the size of the intestinal lumen may be reduced. 相似文献