全文获取类型
收费全文 | 7496篇 |
免费 | 3422篇 |
专业分类
林业 | 206篇 |
农学 | 436篇 |
基础科学 | 5篇 |
1370篇 | |
综合类 | 330篇 |
农作物 | 125篇 |
水产渔业 | 2543篇 |
畜牧兽医 | 4527篇 |
园艺 | 28篇 |
植物保护 | 1348篇 |
出版年
2021年 | 137篇 |
2020年 | 476篇 |
2019年 | 1024篇 |
2018年 | 899篇 |
2017年 | 943篇 |
2016年 | 934篇 |
2015年 | 827篇 |
2014年 | 810篇 |
2013年 | 982篇 |
2012年 | 501篇 |
2011年 | 494篇 |
2010年 | 612篇 |
2009年 | 260篇 |
2008年 | 263篇 |
2007年 | 136篇 |
2006年 | 160篇 |
2005年 | 145篇 |
2004年 | 146篇 |
2003年 | 151篇 |
2002年 | 153篇 |
2001年 | 120篇 |
2000年 | 148篇 |
1999年 | 42篇 |
1998年 | 11篇 |
1997年 | 17篇 |
1995年 | 12篇 |
1994年 | 15篇 |
1993年 | 11篇 |
1992年 | 32篇 |
1991年 | 19篇 |
1990年 | 39篇 |
1989年 | 27篇 |
1988年 | 21篇 |
1987年 | 27篇 |
1986年 | 22篇 |
1985年 | 18篇 |
1984年 | 16篇 |
1982年 | 12篇 |
1981年 | 11篇 |
1980年 | 12篇 |
1979年 | 11篇 |
1978年 | 12篇 |
1977年 | 15篇 |
1975年 | 12篇 |
1974年 | 15篇 |
1973年 | 11篇 |
1972年 | 14篇 |
1971年 | 11篇 |
1970年 | 12篇 |
1969年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
141.
Buck BC Ulrich R Kuiper H Reinacher M Peters M Heimberg P Holsteg M Puff C Haas L Ganter M Distl O 《Berliner und Münchener tier?rztliche Wochenschrift》2011,124(7-8):329-336
Profiles of blood cell counts were evaluated for 15 calves from three different farms. These calves showed petechia in the mucous membranes and in the skin and prolonged secondary bleeding after puncture. The clinical course of the disease could be observed in eleven calves. With exception of one case, the blood cell counts indicated a severe anaemia, leukocytopenia and thrombocytopenia. Out of these 15 calves, six calves survived and the other nine calves died or had to be euthanized due to the severity of the disease. Necropsy of these nine calves revealed petechia in the skin, subcutis, muscles, in inner organs and all serous membranes. Pathohistological examination showed a depletion of the bone marrow and lymphatic tissue in eight calves. These findings confirmed the diagnosis of bovine neonatal pancytopenia (BNP) for eight of these nine calves. Bluetongue virus serotype 8 was tested negatively using PCR. Bovine virus diarrhoea virus (BVDV) was negatively tested using immunofluorescence and cell culture and salmonella species were negatively tested in seven dissected calves. A cluster of toxins was negatively tested in one of the dissected calves. All 15 calves had high antibody titres for BVDV. The BVDV-antibody titres from twelve dams with affected calves were positive in six cases and not detectable in the other six cases. In three of the six dams with not detectable BVDV-antibody titres, calves were fed with colostrum of a further dam with high BVDV-antibody titres. In the further three dams without detectable BVDV-antibody titres, we could not ascertain which colostrum has been fed to the calves. BVDV-specific antigen could not be detected in any of the samples from the calves and dams tested. Using the activity of the gamma-glutamyl-transferase, we assumed a sufficient supply with colostrum for the examined calves.The cause for the occurrence of these BNP cases was due to bone marrow depletion.The reason for the bone marrow depletion remained unclear. However, it was obvious that the BNP described here is highly likely caused by colostrum from cows with positive BVDV-antibody titres. 相似文献
142.
AE Domínguez‐Rebolledo F Martínez‐Pastor AF Bisbal JL Ros‐Santaella O García‐Álvarez A Maroto‐Morales AJ Soler JJ Garde MR Fernández‐Santos 《Reproduction in domestic animals》2011,46(3):393-403
Oxidative stress represents a challenge during sperm manipulation. We have tested the effect of increasing hydrogen peroxide (H2O2) levels on red deer spermatozoa after cryopreservation, and the role of male‐to‐male variation in that response. In a first experiment, eight thawed samples were submitted to 0, 25, 50, 100 and 200 μm H2O2 for 2 h at 37°C. Intracellular reactive oxygen species (H2DCFDA‐CM) increased with H2O2 concentration, but we only detected a decrease in sperm function (motility by CASA and chromatin damage by sperm chromatin structure assay) with 200 μm . Lipoperoxidation assessed by the thiobarbituric acid reactive substance (TBARS) method increased slightly with 50 μm H2O2 and above. In a second experiment, samples from seven males were submitted to 0 and 200 μm H2O2 for 2 h, triplicating the experiment within each male. Males differed at thawing and regarding their response to incubation and H2O2 presence. We found that the kinematic parameters reflected male‐to‐male variability, whereas the response of the different males was similar for lipid peroxidation and viability. A multiparametric analysis showed that males grouped differently if samples were assessed after thawing, after incubation without H2O2 or after incubation with H2O2. Red deer spermatozoa are relatively resilient to H2O2 after thawing, but it seems to be a great male‐to‐male variability regarding the response to oxidative stress. The acknowledgement of this individual variability might improve the development of optimized sperm work protocols. 相似文献
143.
144.
145.
A Homozygous RAB3GAP1:c.743delC Mutation in Rottweilers with Neuronal Vacuolation and Spinocerebellar Degeneration 下载免费PDF全文
146.
Analgesic efficacy of an oral transmucosal spray formulation of meloxicam alone or in combination with tramadol in cats with naturally occurring osteoarthritis 下载免费PDF全文
147.
148.
KC Silva‐Santos CR Ferreira GMG Santos MN Eberlin LS Siloto CO Rosa TN Marcantonio MM Seneda 《Reproduction in domestic animals》2014,49(5):711-718
The aim of the present study was to compare the lipid profile in oocytes of indicus and 1/2 indicus × taurus cows with high and low antral follicle count (AFC)/oocyte yields. After an OPU procedure (D0), antral follicles ≥3 mm were counted by ultrasonography (D4, 19, 34, 49, 64), and cows were assigned to groups with either high AFC (≥30 follicles; indicus, NH group; 1/2 indicus × taurus, AH group) or low AFC (≤15 antral follicles; indicus, NL group; 1/2 indicus × taurus, AL group). The lipid profiles of the oocytes were determined by MALDI‐MS. For GI, GII and GIII oocytes, the indicus samples tend to cluster separately from the 1/2 indicus × taurus samples. The lipid species [PC (P‐38:5) + H]+ and/or [PC (P‐36:2) + Na]+, [PC (38:2) + H]+, [PC (38:5) + Na]+ and [TAG (60:8) + NH4]+ were more abundant in indicus (NH and NL groups) than 1/2 indicus × taurus. The higher lipid content in the indicus oocytes likely reflects differences in the rate of lipid metabolism and may contribute to oocyte competence and embryo development. 相似文献
149.
150.