全文获取类型
收费全文 | 27626篇 |
免费 | 231篇 |
国内免费 | 165篇 |
专业分类
林业 | 1386篇 |
农学 | 273篇 |
基础科学 | 90篇 |
3837篇 | |
综合类 | 6306篇 |
农作物 | 841篇 |
水产渔业 | 291篇 |
畜牧兽医 | 13998篇 |
园艺 | 150篇 |
植物保护 | 850篇 |
出版年
2014年 | 107篇 |
2013年 | 85篇 |
2012年 | 2154篇 |
2011年 | 2483篇 |
2010年 | 511篇 |
2009年 | 302篇 |
2008年 | 2037篇 |
2007年 | 2208篇 |
2006年 | 2086篇 |
2005年 | 1993篇 |
2004年 | 1859篇 |
2003年 | 1779篇 |
2002年 | 1570篇 |
2001年 | 1087篇 |
2000年 | 1484篇 |
1999年 | 584篇 |
1998年 | 109篇 |
1997年 | 120篇 |
1996年 | 102篇 |
1995年 | 128篇 |
1994年 | 180篇 |
1993年 | 214篇 |
1992年 | 239篇 |
1991年 | 206篇 |
1990年 | 234篇 |
1989年 | 187篇 |
1988年 | 216篇 |
1987年 | 191篇 |
1986年 | 180篇 |
1985年 | 189篇 |
1984年 | 213篇 |
1983年 | 156篇 |
1982年 | 153篇 |
1981年 | 122篇 |
1980年 | 123篇 |
1979年 | 71篇 |
1978年 | 64篇 |
1975年 | 59篇 |
1974年 | 73篇 |
1973年 | 60篇 |
1972年 | 53篇 |
1971年 | 57篇 |
1966年 | 62篇 |
1963年 | 78篇 |
1960年 | 61篇 |
1958年 | 67篇 |
1957年 | 55篇 |
1956年 | 61篇 |
1955年 | 61篇 |
1954年 | 59篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Immunogenic properties of a bovine herpesvirus-1 (BHV-1) recombinant expressing major pseudorabies virus (PrV) glycoproteins in combination 总被引:1,自引:0,他引:1
Ikeda Y Shibata I Xuan X Matsumoto Y Otsuka H 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2000,62(8):849-859
A recombinant bovine herpesvirus type 1 (BHV-1), designated BHV-1/TF17-1, which expresses pseudorabies virus (PrV) glycoproteins gB, gC, gD, gE and gI in combination was constructed. To test the protective immunity, 10 mice were inoculated with BHV-1/TF17-1 and three weeks later 10 mice were intraperitoneally (i.p.) challenged with 20 LD50 virulent PrV (YS-81). BHV-1/TF17-1 protected all the mice from the PrV lethal challenge while all the control mice died in around 3 days. Mice vaccinated with BHV-1/TF17-1 acquired high PrV-neutralizing antibody titers and demonstrated strong delayed type hypersensitivity responses and moderate in vitro lymphocyte proliferative responses to PrV antigen. Since the major PrV glycoproteins were integrated into virions (probably into viral envelope), BHV-1/17-1 was neutralized with anti-PrV antiserum. However, the susceptibility of BHV-1/TF17-1 to anti-PrV antiserum is 2- to 4-fold lower than that of PrV vaccine lines. Our results demonstrated the possibility of BHV-1/17-1 as a vaccine to protect piglets from Audjesky's disease where maternal antibodies against PrV interfere attenuated live PrV vaccines. 相似文献
992.
Hagiwara S Kawai K Anri A Nagahata H 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2003,65(3):319-323
The concentrations of lactoferrin (Lf) in quarter milk from normal lactating cows and subclinical mastitic cows were measured to determine whether the Lf concentration in milk is influenced by the age of the cow, the stage of lactation, number of milk somatic cells and the presence of pathogens. Lf concentrations in 111 quarter milk samples from 28 normal lactating cows and 270 quarter milk samples from 198 subclinical mastitic cows were measured by means of a single radial immunodiffusion test. Lf concentrations (means +/- standard deviations; logarithmic form) in normal cows and subclinical mastitic cows were 2.23 +/- 0.39 and 2.70 +/- 0.39, respectively. The mean milk Lf concentration (log) in subclinical mastitic cows was significantly (p<0.01) higher than that in normal cows. The mean milk Lf concentration (log) in normal lactating cows aged 5 years was lower than those in normal lactating cows aged 2 years (p<0.01) and 3 years (p<0.05). The results showed that the milk Lf concentration (log) is associated with age of the dairy cow (one-way analysis of variance test, p<0.01). The mean milk Lf concentration (log) in the latter lactational period tended to be higher than those in the peak and middle periods. Milk Lf concentrations (log) tended to be proportional to the level of the somatic cell count (SCC) score. Mean milk Lf concentrations (log) in subclinical mastitic cows infected with Staphylococcus aureus and with other streptococci species were significantly (p<0.01) higher than those in cows infected with coagulase-negative staphylococci and with Corynebacterium bovis. 相似文献
993.
Takayama I Kubo M Takenaka A Fujita K Sugiyama T Arai T Yoneda M Sato H Yanai T Kai C 《Comparative immunology, microbiology and infectious diseases》2009,32(6):539-549
Ten wild masked palm civets infected with canine distemper virus (CDV), captured in Japan from 2005 to 2007, were histopathologically and phylogenetically analyzed. Phylogenetic analysis based on the amino acid sequences of the H protein of two CDV isolates from masked palm civets revealed that the two isolates were classified into the clade of recent isolates in Japan. Histopathologically marked lesions of virus encephalitis were present in the brain, whereas gastrointestinal lesions were absent or at a mild degree. The distribution of the lesions resembles that of recent CDV cases in dogs. Therefore, recent CDV infections in masked palm civets could be caused by recently prevalent CDV in dogs. The possibility of the masked palm civet as a spreader of CDV among wildlife is also discussed. 相似文献
994.
新植火炬松对于种植时施用氮肥通常没有反应,部分原因是施肥处理往往增加了杂草与林木的竞争。不过,通过施肥有使松树加速占领林地,减少阔叶树的竞争,以及缩短轮伐期等的可能性,所以此种处理仍能引起很大兴趣。通过施用氮肥促进新植火炬松生长的关键是抑制杂草。植物之间的竞争引起新植松树水分紧张。因此,有必要进行在种植时使用除草剂与氮肥相结合的试验。 相似文献
995.
Surprisingly few commercial ELISAs are available for the detection of Toxoplasma gondii infection in animals, and none for use in sheep have been evaluated. We thus compared the Bommeli Diagnostics ELISA Toxotest for the detection of T. gondii antibodies in ruminants with the reference modified agglutination test (MAT) in a series of 180 sheep sera. ELISA results were analysed at two cut-off levels (30%, comprising both weakly positive and positive results, and 100%, comprising only positive results), and compared with MAT at three cut-off levels (titre of 1 : 25, 1 : 50 and 1 : 100). The results showed a moderate agreement of ELISA at both cut-offs (kappa = 0.46 and 0.51) with MAT at a cut-off titre of 1 : 100. However, the specificity and positive predictive value were above 95% only at an ELISA cut-off of 100%, indicating its potential as a diagnostic test, particularly in areas with a high prevalence of infection. On the other hand, lower sensitivity and negative predictive value limit its value as a screening test. Thus, the ELISA Toxotest may be used for quick diagnosis of T. gondii infection in sheep in the field, i.e. for the differential diagnosis of ovine abortion storms. 相似文献
996.
Maruyama H Miura T Sakai M Koie H Yamaya Y Shibuya H Sato T Watari T Takeuchi A Tokuriki M Hasegawa A 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2004,66(5):573-575
The incidence of DIC in 208 dogs with a malignant tumor was evaluated. The incidence of DIC was 9.6% in dogs with a malignant tumor which was a solid tumor in all. In 164 dogs with a malignant solid tumor, the incidence of DIC was 12.2%. The incidence of DIC in dogs with hemangiosarcoma, mammary gland carcinoma and adenocarcinoma of the lung was significantly higher than that in dogs with other malignant tumors. These results suggested that special care in looking for DIC should be taken in dogs with a malignant solid tumor. 相似文献
997.
998.
The responses of five lactating ewes to experimental mammary infection with Staphylococcus epidermidis were examined. Infection caused an intense but transient influx of neutrophils into milk, which peaked at 8 h and was accompanied by mild fever and mild leukopaenia in blood. No other signs of systemic infection were observed. Number of staphylococci in milk decreased logarithmically until 24 h, were absent from three ewes at 48 h and then increased in number or re-emerged in four of the five ewes at 72 or 144 h. At all times milk appeared grossly normal. Expression of the adhesion molecules CD11b and CD18 increased on neutrophils in milk at 24 h then tended to decline over subsequent days. The proportion of lymphocytes positive for CD4, CD8, WC1 and MHCII tended to decrease from 24 to 72 h then increased at 144 h. Cytokines in milk were measured by ELISA. IL-8 was elevated in infected glands at 2 h, peaked at 24 h and remained elevated until the final sampling at 144 h. IL-6 was transiently elevated at 4 and 8 h while IL-1beta remained elevated from 8 until 144 h. The results suggest that the intense early neutrophil infiltrate eliminated most but not all bacteria and a state of subclinical infection ensued. After 24 h , leukocyte numbers in milk declined while cytokines, especially IL-8 remained elevated, suggesting that sensitivity or responsiveness of gland to inflammatory signals decreased as infection progressed. This attenuation of the host defence response may have contributed to the failure of the gland to eliminate bacteria and may be an important feature of the development of chronic and subclinical mastitis. 相似文献
999.
Since several years, there are claims from various sides to introduce and establish test methods and approval procedures concerning mass-producted standard farm equipment and husbandry systems in Germany. Such a procedure should be closely related to practical conditions, feasible and promoting innovation. The aim is to improve animal welfare, to relieve the authorities of single case testing and to create legal confidence for both, manufacturers and livestock owners. 相似文献
1000.
Maeda Y Tanaka R Ohtsuka H Matsuda K Tanabe T Oikawa M 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2011,73(7):957-960
This study compared the immunosuppressive effects of dexamethasone (DEX), flunixin meglumine (FLU) and meloxicam (MEL) on the peripheral blood mononuclear cells (PBMCs) of seven healthy Holstein calves in vitro. DEX significantly inhibited lymphocyte proliferation and expression of interferon (IFN)-γ, interleukin (IL)-2 and IL-4 messenger RNA (mRNA) in comparison with FLU and MEL. FLU and MEL dose-dependently inhibited lymphocyte proliferation, but did not significantly reduce mRNA expression. Our in vitro study indicates that steroidal anti-inflammatory drugs (SAIDs) as well as nonsteroidal anti-inflammatory drugs (NSAIDs) have immunosuppressive effects on calf PBMCs. These findings are important for assessing the indications and complications of NSAIDs in calves. 相似文献