全文获取类型
收费全文 | 18217篇 |
免费 | 73篇 |
国内免费 | 1篇 |
专业分类
林业 | 3788篇 |
农学 | 1364篇 |
基础科学 | 138篇 |
2983篇 | |
综合类 | 815篇 |
农作物 | 2149篇 |
水产渔业 | 1913篇 |
畜牧兽医 | 2053篇 |
园艺 | 1120篇 |
植物保护 | 1968篇 |
出版年
2023年 | 7篇 |
2022年 | 21篇 |
2021年 | 39篇 |
2020年 | 35篇 |
2019年 | 23篇 |
2018年 | 2768篇 |
2017年 | 2731篇 |
2016年 | 1222篇 |
2015年 | 111篇 |
2014年 | 90篇 |
2013年 | 169篇 |
2012年 | 887篇 |
2011年 | 2224篇 |
2010年 | 2148篇 |
2009年 | 1305篇 |
2008年 | 1405篇 |
2007年 | 1659篇 |
2006年 | 147篇 |
2005年 | 215篇 |
2004年 | 203篇 |
2003年 | 238篇 |
2002年 | 116篇 |
2001年 | 60篇 |
2000年 | 90篇 |
1999年 | 34篇 |
1998年 | 18篇 |
1997年 | 3篇 |
1996年 | 9篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 18篇 |
1992年 | 27篇 |
1991年 | 27篇 |
1990年 | 30篇 |
1989年 | 29篇 |
1988年 | 30篇 |
1987年 | 27篇 |
1986年 | 16篇 |
1985年 | 22篇 |
1984年 | 9篇 |
1983年 | 9篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 10篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1969年 | 5篇 |
1968年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Mouse pronuclear stage embryos with intact slit zona pellucida (manipulated) were cultured in vitro until the hatched blastocyst stage in simplex optimized medium with higher K+ concentration (KSOM) prepared with three different water types: tap, deionized reverse osmosis (D‐O) water and Milli‐Q system (M‐Q) water. The culture media were supplemented with or without protein and ethylenediaminetetraacetic acid (EDTA, disodium salt). The rates of hatched blastocysts were significantly affected (p < 0.01) by micromanipulation, protein supplement and water source. The water source has no influence (p > 0.05) on development in EDTA‐supplemented protein‐free culture media, whereas in EDTA‐ and protein‐free culture media, the water quality significantly (p < 0.001) affected the rates of development, with higher rates in media prepared with M‐Q water. The micromanipulated embryos showed higher sensitivity to the water quality (p < 0.01). It worth mentioning that the rates of hatched blastocysts in protein‐free culture media were very low (0–7.5%). Furthermore, the three different water types were analysed by measuring the electrical conductivity, inorganic ions, total organic carbon and endotoxins to evaluate the purity. M‐Q water showed the lowest levels of inorganic ion, total organic carbon and endotoxin concentrations. We concluded that manipulated mouse embryos are good system to evaluate the quality of water used in biological system. 相似文献
4.
5.
Characterisation of cross-reactivity of virus neutralising antibodies induced by feline panleukopenia virus and canine parvoviruses 总被引:1,自引:0,他引:1
K. Nakamura Y. Ikeda T. Miyazawa Y. Tohya E. Takahashi M. Mochizuki 《Research in veterinary science》2001,71(3):219-222
It was recently reported that canine parvoviruses (CPV) had entered cat populations and induced disease in infected cats, while they had affected only dogs in the past. It is important to determine whether conventional feline panleukopenia virus (FPLV) vaccines protect against recent CPV infections. In this study, the cross-reactivity of virus-neutralising (VN) and haemagglutinin-inhibition (HI) antibodies in cats induced by FPLV and CPV s were examined. Lower cross-reactivities of VN and HI antibodies against each CPV strain were observed in cats experimentally inoculated with FPLV or vaccinated with an inactivated FPLV vaccine. In addition, we revealed the existence of a novel type of FPLV, which reacted weakly with antibodies induced by the conventional FPLV vaccine. 相似文献
6.
E Ogawa A Kawakami T Yagi T Amaya H Fujise R Takahashi 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1992,54(1):57-62
Oxidative damage to the membrane in canine erythrocytes with inherited high Na, K-ATPase activity (HK cells) was compared with that in normal canine cells (LK cells). When 30 mM beta-acetylphenylhydrazine (APH) was applied to HK and LK cells, lipid peroxidation and hemoglobin denaturation occurred. Lipid peroxidation determined from malondialdehyde (MDA) formation was significantly lower in HK than in LK cells so far as endogenous glutathione (GSH) concentration was maintained at appropriate levels. With the depletion of GSH, MDA formation was accelerated and difference between HK and LK cells was not significant. Denatured hemoglobin bound to the membrane protein was less in HK than in LK cells. During incubation with APH, osmotic fragility increased markedly in LK cells, while HK cells showed very little change. The amounts of total lipid, total and free cholesterol, glycolipid, phospholipid and fatty acids were essentially the same in both cell types. Fatty acid compositions showed very small differences. The membrane of HK cells thus appear to have greater protection against oxidative damage induced by APH, owing to the presence of excess GSH in HK cells. The capability of HK cells to withstand oxidative damage would not be due to differences in membrane lipid compositions. 相似文献
7.
8.
Y Takahashi M Iida Y Nishida Y Kido 《Nippon juigaku zasshi. The Japanese journal of veterinary science》1989,51(5):995-1001
Eight calves, weighing 50-150 kg, were given intramuscularly 5 ml of ampicillin (ABPC) aqueous suspensions (200 mg potency/ml) in their right and left gluteal and femoral regions. All calves were sacrificed one hour later to confirm the location of injected drug. The drug was found in a muscle layer when injected with a needle 15 mm long to the following positions, 1. the midpoint between the central position of the gluteal region (CG) and the tuber coxae (M-CTc), 2. the midpoint between CG and the tuber ossis ischii (M-CTo), 3. the central position of M. semimembranaceus in the femoral region (CF). Seven calves, weighing 130-150 kg, were given intramuscularly 5 ml of ABPC suspensions at M-CTo and CF and sacrificed one hour (4 calves) and 3 days (3 calves) later. ABPC diffused along the long axis of the muscle fibers but not to the radial direction. ABPC was detected only in the injected muscle layer even after 3 days indicating that the drug did not diffuse to the neighboring muscles. In the injected muscle layer, concentration of ABPC was remarkably different from part to part. From these results, sampling of the injected muscle for the drug residue study was proposed as follows: 1. isolate about 100 g of muscle just under the stick point marked on the skin considering the direction of drug diffusion, and 2. isolate separately about 200 g of the surrounding muscle to confirm if the sampling is appropriate. 相似文献
9.
Y Takimoto M Hishinuma Y Takahashi H Kanagawa 《Nippon juigaku zasshi. The Japanese journal of veterinary science》1989,51(5):879-885
Rosette inhibition tests for the detection of early pregnancy factor (EPF) were performed on naturally ovulated and superovulated mice from day 2 of pregnancy up to 4 days after parturition. In both groups of mice, the rosette inhibition titre (RIT) increased on day 2 of pregnancy, and persisted at high levels until day 15. Thereafter, the RITs of both groups of mice decreased to the non-pregnancy range. No significant differences of the mean RITs between these two groups were observed during the high RIT period. These results showed that the superovulatory treatment did not cause any changes or interference in the detection of EPF. In order to investigate the initial time of appearance of EPF in the maternal circulation in relation to the stage of fertilization, measurement of RIT and examination of the fertilization stage were carried out on superovulated mice 1 day after mating. The mean RIT of mice with pronucleus stage ova was significantly (p less than 0.01) higher than that of mice with sperm-penetrated ova. EPF was considered to appear in the maternal peripheral blood at the pronucleus stage. 相似文献
10.