全文获取类型
收费全文 | 168559篇 |
免费 | 9257篇 |
国内免费 | 97篇 |
专业分类
林业 | 7571篇 |
农学 | 5588篇 |
基础科学 | 1000篇 |
21153篇 | |
综合类 | 26788篇 |
农作物 | 6371篇 |
水产渔业 | 8447篇 |
畜牧兽医 | 87918篇 |
园艺 | 2159篇 |
植物保护 | 10918篇 |
出版年
2019年 | 1653篇 |
2018年 | 2580篇 |
2017年 | 2868篇 |
2016年 | 2647篇 |
2015年 | 2325篇 |
2014年 | 2854篇 |
2013年 | 6775篇 |
2012年 | 5122篇 |
2011年 | 6035篇 |
2010年 | 4087篇 |
2009年 | 4177篇 |
2008年 | 6035篇 |
2007年 | 5829篇 |
2006年 | 5514篇 |
2005年 | 5088篇 |
2004年 | 4868篇 |
2003年 | 4906篇 |
2002年 | 4546篇 |
2001年 | 5615篇 |
2000年 | 5435篇 |
1999年 | 4395篇 |
1998年 | 1748篇 |
1997年 | 1744篇 |
1996年 | 1627篇 |
1995年 | 1928篇 |
1994年 | 1636篇 |
1993年 | 1670篇 |
1992年 | 3337篇 |
1991年 | 3452篇 |
1990年 | 3430篇 |
1989年 | 3487篇 |
1988年 | 3156篇 |
1987年 | 3176篇 |
1986年 | 3145篇 |
1985年 | 2982篇 |
1984年 | 2447篇 |
1983年 | 2177篇 |
1982年 | 1478篇 |
1979年 | 2107篇 |
1978年 | 1692篇 |
1977年 | 1489篇 |
1976年 | 1450篇 |
1975年 | 1524篇 |
1974年 | 1880篇 |
1973年 | 1887篇 |
1972年 | 1880篇 |
1971年 | 1701篇 |
1970年 | 1712篇 |
1969年 | 1604篇 |
1967年 | 1402篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
A young female Somali cat was referred for investigation of chronic intermittent haematuria. Petechiae were found on the ears and ventral abdomen and further investigation revealed severe thrombocytopenia and megakaryocyte hyperplasia. Direct marrow immunohistochemistry detected anti-megakaryocyte autoantibody (Immunoglobulin G), but extensive investigation failed to find secondary causes of immune-mediated thrombocytopenia, so a diagnosis of primary (autoimmune) immune-mediated thrombocytopenia was concluded. Thrombocytopenia persisted despite aggressive immunosuppressive therapy (prednisolone, azathioprine and vincristine) but resolved after oral prednisolone was replaced with dexamethasone. 相似文献
962.
H Taniyama K Hirayama Y Kagawa T Kurosawa M Tajima T Yoshino H Furuoka 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1999,61(7):803-810
Histological and immunohistochemical studies were carried out on the pancreas of twelve cattle of insulin-dependent diabetes mellitus (IDDM). They showed clinical signs such as persistent hyperglycemia, glycosuria and decreased glucose tolerance, and some cases accompanied with or without ketonuria. Histopathologically, eight cattle were diagnosed as chronic IDDM, while others were acute IDDM. The most characteristic lesions of the pancreas in chronic IDDM showed a decrease in the size and number of pancreatic islets, interlobular and interacinar fibrosis, mild lymphocytic insulitis, and vacuolation of a few islets. Almost all cells in the atrophied islets had a small amount of ungranulated cytoplasm. Immunohistochemical examination revealed that the atrophied islet cells did not react to anti-insulin antibody, but occasionally reacted to anti-glucagon or somatostatin antibodies. A few solitary islets with mild lymphocytic infiltration, necrotic islets with occasional calcification, and atrophied islets with mild fibrosis were also observed. A few islets consisted of many islet cells with vacuolated cytoplasm including a small number of insulin-positive granules. Accumulation of glycogen granules was occasionally observed in these islets. Islet fibrosis was due to the proliferation of collagen fibers reactive to both anti-collagen type I and type III antibodies. In acute IDDM, the major islets consisted of the cells with vacuolated cytoplasm indicating the degranulation of islet cells. These islets contained many islet cells with shrunken cytoplasm and karyorrhectic nuclei. Lymphocytic infiltration was frequently observed in the islets which consisted of many islet cells having karyorrhectic nuclei and vacuolated and severely degranulated cytoplasm. Immunohistochemically, islet cells with vacuolated cytoplasm had a small amount of insulin-positive granules, suggesting severe degranulation of beta-cells. An increase in acinar islet-cells and proliferation of ductal epithelial cells showing insulin-immunoreactivity were observed. Bovine IgG-immunoreactive islet cells were frequently seen in the vacuolated islets. In summary, pathological observations suggested that beta-cells were being destroyed by an inflammatory process which selectively affected the pancreatic islets. Lymphocytic insulitis and anti-bovine immunoreactive islet cells were thought to be the most significant changes in determining the etiology and pathogenesis of bovine IDDM, and suggested their role in anti-islet autoimmunity in this form of diabetes. 相似文献
963.
Twenty horses with central and third tarsal bone slab fractures, were treated internal fixation. Eighteen of the 20 cases were Standardbred trotters, one was a Thoroughbred racehorse and one a Swedish Warmblood. The central tarsal bone (CT) was involved in 12 cases and the third tarsal bone (T3) in 8 cases. The fractures were treated by lag screw fixation with one (18 cases) or two (2 cases) 3.5 or 4.5 mm cortical screws. Horses were confined to stall rest for one month and then put on a gradually increasing exercise programme. Convalescence time was 3-8 months until the fracture had healed and training could be resumed. Fifteen of the horses regained athletic soundness. Thirteen of the horses (72%) raced after surgery (12 Standardbreds and 1 Thoroughbred). Nine (69%) of these 13 horses won races after surgery. 相似文献
964.
Four cases of ulceration and stricture of the right dorsal colon were encountered. Ulceration of the right dorsal colon is generally associated with nonsteroidal anti-inflammatory drug (NSAID) toxicosis but there are few reports of stricture following ulceration. All four horses had recent phenylbutazone use: three had been given doses well in excess of the recommended dose and in one the dose was marginally above those recommended but was combined with administration of other NSAIDs. All four horses presented with intermittent low-grade colic, weight loss and ventral oedema. Diarrhoea was also seen in three of them. All had hypoproteinaemia due to severe hypoalbuminaemia, and hyperfibrinogenaemia. Hypoalbuminaemia was less severe in one horse and this horse was successfully managed medically. Two cases were definitively diagnosed at exploratory celiotomy and two at necropsy. Exploratory celiotomy was performed in two horses: one was euthanased at surgery and one was managed successfully with medical treatment and remained normal 1 year after surgery. Medical management included feeding of a low-roughage pelleted ration, corn oil, psyllium mucilloid, and discontinuation of NSAID administration. 相似文献
965.
Alicia M. Skelding Alexander Valverde Greg Kilburn 《Veterinary anaesthesia and analgesia》2021,48(3):407-414
ObjectiveTo evaluate anesthetic conditions and postoperative analgesia with the use of intraoperative constant rate infusions (CRIs) of fentanyl–lidocaine or fentanyl–ketamine in dogs undergoing thoracolumbar hemilaminectomy.Study designProspective, randomized, blinded, clinical study.AnimalsA total of 32 client-owned dogs.MethodsDogs were premedicated with fentanyl (5 μg kg–1) administered intravenously (IV), anesthesia was induced with IV alfaxalone and maintained with isoflurane. Fentanyl (0.083 μg kg–1 minute–1) was infused IV with either ketamine (0.5 mg kg–1; then 40 μg kg–1 minute–1; group KF) or lidocaine (2 mg kg–1; then 200 μg kg–1 minute–1; group LF) assigned randomly. Heart rate, noninvasive arterial pressures, respiratory rate, esophageal temperature, end-tidal partial pressure of carbon dioxide and isoflurane concentration were recorded throughout anesthesia. Maintenance of anesthesia, recovery and postoperative pain (Glasgow Composite Pain Scale) were scored. Cardiopulmonary data were analyzed using a two-way anova with repeated measures, demographics of the two groups with a t test, and scores with Mann–Whitney U test, with p < 0.05.ResultsAll dogs recovered from anesthesia without complications. No significant difference was found between groups for cardiopulmonary variables, total anesthesia time, sedation score and requirement for postoperative sedation or for rescue analgesia. Anesthetic maintenance score was of lower quality in KF than in LF [median (interquartile range): 0 (0–0.5) versus 0 (0–0); p = 0.032)], but still considered ideal. Recovery score was higher and indicative of less sedation in LF than in KF [1 (1–1.5) versus 0.5 (0–1); p < 0.0001]. Pain score was higher in KF than in LF [2 (1–3) versus 1 (1–2); p = 0.0009].Conclusions and clinical relevanceBoth CRIs of KF and LF provided adequate anesthetic conditions in dogs undergoing thoracolumbar hemilaminectomy. Based on requirement for rescue analgesia, postoperative analgesia was adequate in both groups. 相似文献
966.
The Prevention and Control of Epidemics of Acute Undifferentiated Diarrhea of Beef Calves in Western Canada 总被引:1,自引:0,他引:1 下载免费PDF全文
O. M. Radostits S. D. Acres 《The Canadian veterinary journal. La revue veterinaire canadienne》1980,21(9):243-249
It is frequently evident that outbreaks of diarrhea occur in spite of apparent “good management” and “good calving conditions”. This observation underlies the fact that we still do not understand many of the epidemiological factors which contribute to calf diarrhea outbreaks. For example, we still lack biological criteria by which to judge the degree of crowding and the degree of stress. Nevertheless, application of the principles described above will prevent or decrease the severity of many annual epidemics. To be successful, a program of prevention and control should be discussed with producers long before the calving season, preferably during the preceding summer or fall. Implementation of a complete program may take several calving seasons and producers should be made aware that prevention by improved management is an on-going, evolutionary process. More and improved vaccines are becoming available; however, as is the case with most biologicals, their impact cannot be determined until after they have been used for several years. They should be recognized as only one of several managent tools at the disposal of the veterinarian and livestock producer. 相似文献
967.
D H Lloyd D M Jenkinson P N Miller T J Sykes 《Veterinary immunology and immunopathology》1987,16(3-4):251-257
Studies of the temporal changes in specific antibody titres to D. congolensis in serum and washings from inoculated and uninoculated skin indicate that production of IgG1 and IgG2 antibody at the skin surface is a transudative process related to serum antibody concentration. Transport of IgM is likely to be based on a similar mechanism but that of IgA appears to depend on a local secretory process. 相似文献
968.
A mainframe relational database management system (RDBMS), ORACLE, has been applied to small animal clinical records to facilitate storage and querying of case data for clinical and epidemiological use. Coded records are entered into the computer via a “user-friendly” interface which validates the input. Clinicians' queries similarly utilise an interface that generates query commands from four simple queries. Epidemiologists' queries, in contrast, require considerable flexibility and so use the main RDBMS language, SQL*Plus. A data administrator manages the security and integrity of the RDBMS. 相似文献
969.
Bluetongue virus type 16, isolated from sheep in Egypt, was injected to 4 normally cycling Barki ewes and caused high levels of inhibin. This was assayed by a biological method, using suppression of the luteinising hormone (LH) of castrated rats. Albumin (fraction 2) was injected to normally cycling ewes. The sera of injected ewes were investigated 1 day after injection and weekly up to the 4th one injection. There was a gradual decrease of LH (4.8 +/- 0.52 I.U./ml serum) until the minimum level (1.17 +/- 0.25 I.U./ml serum) was reached, in comparison to the control serum LH which was 5.26 +/- 0.52 I.U./ml serum during the dioestrous phase. 相似文献
970.
M J Corbel F A Stuart R A Brewer M Jeffrey R Bradley 《The British veterinary journal》1989,145(4):347-355
Attempts to reproduce in calves the arthropathy associated with Brucella abortus strain 19 (S19) vaccination by direct intra-articular injection of S19 or virulent Brucella cells were unsuccessful. Intra-articular injection of rabbits and a calf with immune complexes isolated from the synovial fluid of a field case produced clinical and histological signs of arthropathy accompanied by the development of rheumatoid factor. 相似文献