全文获取类型
收费全文 | 9008篇 |
免费 | 518篇 |
国内免费 | 13篇 |
专业分类
林业 | 417篇 |
农学 | 463篇 |
基础科学 | 63篇 |
1560篇 | |
综合类 | 691篇 |
农作物 | 881篇 |
水产渔业 | 635篇 |
畜牧兽医 | 3969篇 |
园艺 | 181篇 |
植物保护 | 679篇 |
出版年
2023年 | 46篇 |
2022年 | 111篇 |
2021年 | 199篇 |
2020年 | 181篇 |
2019年 | 180篇 |
2018年 | 235篇 |
2017年 | 239篇 |
2016年 | 229篇 |
2015年 | 214篇 |
2014年 | 294篇 |
2013年 | 465篇 |
2012年 | 493篇 |
2011年 | 597篇 |
2010年 | 400篇 |
2009年 | 364篇 |
2008年 | 499篇 |
2007年 | 476篇 |
2006年 | 439篇 |
2005年 | 381篇 |
2004年 | 358篇 |
2003年 | 334篇 |
2002年 | 308篇 |
2001年 | 262篇 |
2000年 | 207篇 |
1999年 | 166篇 |
1998年 | 81篇 |
1997年 | 51篇 |
1996年 | 49篇 |
1995年 | 45篇 |
1994年 | 49篇 |
1993年 | 62篇 |
1992年 | 102篇 |
1991年 | 88篇 |
1990年 | 104篇 |
1989年 | 89篇 |
1988年 | 49篇 |
1987年 | 67篇 |
1986年 | 54篇 |
1985年 | 61篇 |
1984年 | 65篇 |
1983年 | 56篇 |
1982年 | 55篇 |
1980年 | 38篇 |
1979年 | 41篇 |
1978年 | 56篇 |
1977年 | 46篇 |
1976年 | 43篇 |
1974年 | 46篇 |
1972年 | 39篇 |
1969年 | 45篇 |
排序方式: 共有9539条查询结果,搜索用时 15 毫秒
981.
Park ES Seong JK Yi SJ Kim JS Lee HS Lee IS Yoon YS 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2005,67(7):639-646
This study was carried out to investigate the changes of orexin-A (OXA) and neuropeptide Y (NPY) expression in the hypothalamus of the obese and lean Zucker Diabetic Fatty (ZDF) rats which have a missense mutation in the leptin receptor gene. The mean body weights (MBW) between the obese and lean ZDF rats were significantly different at 28 and 70 postnatal days. However, at 14 postnatal day, there was no significant difference in the MBW between the obese and lean ZDF rats in both male and female. The OXA immunoreactivities were not significantly different between the obese and lean ZDF rats in both sexes at 14, 28, and 70 postnatal days, respectively. The NPY immunoreactivity was higher in the obese than in the lean ZDF rats in both male and female at 28 and 70 postnatal days, whereas there was no significant difference between the obese and lean ZDF rats at 14 postnatal day. These results indicate that both OXA and NPY might halt their roles for food intake in the obese phenotype of the male and female ZDF rats in the preweaning period of 14 postnatal day, whereas NPY might play a main role in the obesity of these rats in the weaning period of 28 and 70 postnatal days. 相似文献
982.
Determining the immune responses to the development of endometritis during the peripartum period may assist in the development of more efficient reproductive management regimens for dairy herds. In this study, we compared the peripartum immune responses of dairy cows that develop endometritis by 4 weeks postpartum (n = 11) to cows that did not develop this disease (n = 19). Blood samples were collected 1 week before calving, just after or during calving, and then at weeks 1, 2, 3, and 4 postpartum. Cows that developed endometriris had significantly higher total leukocyte, neutrophil, lymphocyte, and monocyte counts than the control cows (P < 0.05) at all time points. The leukocytes from cows that developed endometritis were significantly less phagocytic than those from control cows at all sampling time points (P < 0.01). The serum TNFalpha concentrations of the control cows decreased linearly from the prepartum time point (P = 0.0029), but the endometritis cows showed a different profile (P > 0.05). As a result, the serum TNFalpha concentrations were greater in the endometritis group (P < 0.01) than in the control group during the third and fourth weeks postpartum. The greater total leukocyte numbers and neutrophil, lymphocyte and monocyte counts, and the maintenance of elevated serum TNFalpha levels in the cows with endometritis may be due to infection in the postpartum period. Furthermore, the decreased phagocytic capacity of leukocytes during the peripartum period, including at the prepartum time point, makes cows more susceptible to postpartum endometritis. 相似文献
983.
Um SW Kim MS Lim JH Kim SY Seo KM Nam TC 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2005,67(12):1283-1284
This study was performed to evaluate the efficacy of acupuncture on induced chronic arthritis of the dog by thermography. Complete Freund's adjuvant was injected into the left knee joint of 8 dogs to induce arthritis. Acupuncture was applied to BL-40, GB-33, GB-34, and LIV-8 once a week for 4 consecutive weeks, from 3 weeks after induction of chronic arthritis, in treatment group. At 3 weeks of acupuncture treatment, skin temperature difference (DeltaT) of treatment group returned to normal range (< 0.3 degrees C), while DeltaT remained high in non-treatment group. Infrared thermography (IRT) is useful to evaluate the treatment of acupuncture for induced canine chronic arthritis. Therefore, it is considered that clinical application of IRT in arthritis treatment would be also valuable. 相似文献
984.
Nollet H Vanschandevijl K Van Ham L Vanderstraeten G Deprez P 《The Veterinary record》2005,157(21):656-658
Transcranial magnetic stimulation and measurement of the magnetic motor-evoked potentials (MMEPs) in the thoracic and pelvic limbs of four recumbent horses and one recumbent donkey were used to assess the integrity of the descending motor pathways, in order to confirm or exclude a descending motor tract lesion as the cause of the recumbency. In two of the animals abnormal MMEPs were recorded; in one of the horses a lesion along the cervical spinal cord due to a fracture of the fifth cervical vertebra was diagnosed and confirmed by radiography and postmortem examination; in another horse, damage to the peripheral nerves of the left forelimb was diagnosed and confirmed postmortem when a large abscess was found to have been compressing the peripheral nerves at the level of the last cervical vertebra. In the three other animals, normal MMEPs were recorded, and laminitis, rhabdomyolysis and physitis were diagnosed as the causes of the recumbency. 相似文献
985.
Eighteen chickens were immunized subcutaneously with purified type 1 fimbriae from Salmonella enterica serotype Enteritidis at 18 and 21 weeks of age. Evidence of IgG and IgA responses was found in the eggs and in the sera of the immunized hens. Three weeks later, immunized and non-immunized chickens (n=18) were challenged intravenously with 2x10(7) live Salmonella enterica serotype Enteritidis. There was no significant difference in the numbers of eggs laid by immunized and non-immunized birds. The percentage of Salmonella contaminated eggs was significantly higher in the non-immunized group than in the immunized group due to a higher percentage of contamination of the externally disinfected egg shells. There were no statistical differences in the percentages of contaminated yolks and egg whites between control and immunized birds. No differences in the number of colonizing bacteria could be found in the spleen nor in the liver between the immunized and the control groups throughout the experiment. Salmonella was cleared from the ovary of the immunized birds in the second week p.i., in contrast to the control birds where Salmonella was isolated till the third week after infection. Oviducts were significantly more infected in the control group than in the immunized group. Salmonella was cleared from the oviducts at 3 weeks p.i. in the immunized hens but not in the control hens. In conclusion, we demonstrated that the immunization of laying hens with type 1 fimbriae reduced the number of contaminated eggs and reduced the colonization of the reproductive organs. 相似文献
986.
Van Loock M Geens T De Smit L Nauwynck H Van Empel P Naylor C Hafez HM Goddeeris BM Vanrompay D 《Veterinary microbiology》2005,107(1-2):91-101
Two hundred turkey sera from eight Belgian and two French farms were tested for the presence of antibodies against avian pneumovirus (APV), Ornithobacterium rhinotracheale (ORT), Mycoplasma gallisepticum, Mycoplasma meleagridis and Chlamydophila psittaci. At slaughter, C. psittaci, APV and ORT antibodies were detected in 94, 34 and 6.5% of the turkeys, respectively. No antibodies against M. gallisepticum or M. meleagridis were present. Additionally, turkeys on three Belgian farms were examined from production onset until slaughter using both serology and antigen or gene detection. All farms experienced two C. psittaci infection waves, at 3-6 and 8-12 weeks of age. Each first infection wave was closely followed by an ORT infection starting at the age of 6-8 weeks, which was still detectable when the second C. psittaci infection waves started. Animals on farm A were not vaccinated against APV leading to an APV subtype B outbreak accompanying the first C. psittaci infection wave. Despite subtype A APV vaccination on farms B and C, the second C. psittaci infection waves were accompanied (farm B) or followed (farm C) by a subtype B APV infection. On all farms respiratory signs always appeared together with a proven C. psittaci, APV and/or ORT infection. This study suggests an association between C. psittaci, APV and ORT, and indicates the multi-factorial aetiology of respiratory infections in commercial turkeys. All three pathogens should be considered when developing prevention strategies for respiratory disease. 相似文献
987.
988.
OBJECTIVE: To describe clinical findings, surgical treatment, and outcome associated with trichophytobezoar duodenal obstruction in New World camelids. STUDY DESIGN: Retrospective study. ANIMALS: Alpacas (7) and 1 llama. METHODS: Historical and clinical data were obtained from the medical records of New World camelids with a diagnosis of trichophytobezoar duodenal obstruction confirmed by surgical exploration or necropsy. RESULTS: Seven camelids were <1 year old. Abnormal clinical findings included anorexia, reduced fecal output, recumbency, colic, abdominal distension, regurgitation, decreased serum chloride concentration, increased serum bicarbonate concentration, and/or elevated first gastric compartment chloride concentration. Survey abdominal radiographs obtained (4 animals) revealed gastric distension (4) and/or visualization of the obstruction (2). Diagnosis was confirmed at necropsy (1) or surgery (7). Right paracostal celiotomy was performed on all animals and duodenotomy (3) or retropulsion of the trichophytobezoar combined with third compartment gastrotomy (4) was used to remove the obstruction. Six animals survived to discharge and 5 were healthy at follow-up, 8-20 months later. The remaining discharged alpaca was healthy at 12 months but subsequently died of unrelated causes. CONCLUSIONS: Diagnosis of trichophytobezoar duodenal obstruction should be considered in juvenile New World camelids with abdominal distension and hypochloremic metabolic alkalosis. Right paracostal celiotomy can be used for access to the descending duodenum and third gastric compartment for surgical relief of obstruction. CLINICAL RELEVANCE: Duodenal obstruction from bezoars should be considered in New World camelids <1year of age with abdominal distension and hypochloremic metabolic alkalosis. Surgical relief of the obstruction by right paracostal celiotomy has a good prognosis. 相似文献
989.
G Charlier R Strobbe A Van Aert J Leunen 《Comparative immunology, microbiology and infectious diseases》1981,4(3-4):279-283
A method for PEG treatment of bovine sera to be used for cell cultures is presented. The procedure consists in repeated freezing and thawing cycles of the sera, after PEG precipitation until a clear solution is obtained. The sera, so prepared, are homogeneous in composition and appropriate for cell growth in primary cell cultures and cell lines. 相似文献
990.
C D Van Houweling W B Bixler J R McDowell 《Journal of the American Veterinary Medical Association》1977,171(11):1153-1156
Chemical contamination of animal feeds and feed ingredients is of concern to the Food and Drug Administration. Contamination by industrial chemicals such as polychlorinated biphenyls and polybrominated biphenyls; heavy metals such as lead, cadmium, and mercury; and pesticides such as dieldrin and chlordane exemplify the problem in feeds and the resulting problem of tissue residues in human foods. 相似文献