全文获取类型
收费全文 | 1580篇 |
免费 | 100篇 |
国内免费 | 2篇 |
专业分类
林业 | 256篇 |
农学 | 51篇 |
基础科学 | 12篇 |
368篇 | |
综合类 | 113篇 |
农作物 | 39篇 |
水产渔业 | 80篇 |
畜牧兽医 | 653篇 |
园艺 | 18篇 |
植物保护 | 92篇 |
出版年
2023年 | 9篇 |
2022年 | 13篇 |
2021年 | 33篇 |
2020年 | 44篇 |
2019年 | 37篇 |
2018年 | 35篇 |
2017年 | 42篇 |
2016年 | 43篇 |
2015年 | 33篇 |
2014年 | 40篇 |
2013年 | 104篇 |
2012年 | 85篇 |
2011年 | 70篇 |
2010年 | 62篇 |
2009年 | 63篇 |
2008年 | 96篇 |
2007年 | 77篇 |
2006年 | 82篇 |
2005年 | 62篇 |
2004年 | 64篇 |
2003年 | 65篇 |
2002年 | 55篇 |
2001年 | 31篇 |
2000年 | 28篇 |
1999年 | 16篇 |
1998年 | 14篇 |
1997年 | 9篇 |
1995年 | 25篇 |
1994年 | 15篇 |
1993年 | 12篇 |
1992年 | 9篇 |
1991年 | 8篇 |
1990年 | 15篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1974年 | 8篇 |
1970年 | 8篇 |
1968年 | 9篇 |
1958年 | 7篇 |
1957年 | 7篇 |
1939年 | 7篇 |
1938年 | 10篇 |
1935年 | 6篇 |
1931年 | 9篇 |
排序方式: 共有1682条查询结果,搜索用时 578 毫秒
61.
Cryptorchism is an inherited congenital abnormality characterized by the failure of one or both testes to descend into the scrotum. Diagnosis can be difficult if the retained testicular tissue cannot be localized during clinical examination and the history of the animal is unknown, or if the animal shows persistent male behaviour despite the history of successful previous castration. The present case report describes the history of a cryptorchid Lama and the techniques of general anesthesia and laparoscopic cryptorchidectomy advocated. 相似文献
62.
A two-year-old female alpaca suddenly became lame on its right hindlimb. Eight days later clinical and radiographic examinations showed that the patella had become temporarily fixed within the supratrochlear notch of the femur. Under general anaesthesia an abrasion trochleoplasty followed by fascial imbrication was carried out. After two weeks in supporting slings, the animal put full weight on the leg, and six months after the surgery it showed no signs of lameness or recurrence of the upward fixation. 相似文献
63.
Van de Walle GR Favoreel HW Nauwynck HJ Van Oostveldt P Pensaert MB 《Veterinary microbiology》2002,86(1-2):51-57
Addition of pseudorabies virus (PrV)-specific polyclonal immunoglobulins to PrV-infected monocytes induces internalization of plasma membrane anchored viral glycoproteins. This process may interfere with antibody-dependent cell lysis and resembles the well-studied physiological endocytosis process. A confocal study was designed to investigate whether the major cellular components, involved in physiological endocytosis (clathrin, actin, dynein and microtubules), play a role in this virological internalization process. In order to visualize the interaction of endosomes, which contain the internalized viral glycoproteins, with clathrin, actin, dynein and microtubules, a double labeling of viral glycoproteins and different cellular proteins was performed. Porcine monocytes were inoculated with the PrV-strain 89V87 at a multiplicity of infection of 50 for 13h. After the addition of FITC-labeled porcine polyclonal PrV-specific antibodies, cells were fixed with para-formaldehyde at different time points and afterwards permeabilized. The different cellular components were visualized with monoclonal antibodies and a Texas Red-conjugate, with the exception of actin, which was stained with phalloidin-Texas Red. The cells were analyzed by confocal microscopy. A clear co-localization was observed between the viral glycoproteins and clathrin and dynein during the internalization process. The microtubules were in close contact with the internalized vesicles. For actin no co-localization could be observed. It can be stated that clathrin, dynein and microtubules, important components during physiological endocytosis, are also of importance during the antibody-induced internalization of viral glycoproteins. 相似文献
64.
The accuracy of three diagnostic tests for paratuberculosis was evaluated using maximum-likelihood estimation of sensitivity and specificity. We also explored the variety of estimates that can be obtained if the tests are to be used in populations of different composition with regard to infection and disease states. Two enzyme-linked immunosorbent assays (ELISAs) were evaluated separately with the faecal culture (FC). The study was carried out as a cross-sectional field study to cover all likely states of infection with Mycobacterium avium subsp. paratuberculosis.The three basic assumptions for the maximum-likelihood technique were evaluated to validate the results. Our accuracy estimates for the ELISAs were not very different from those previously published, but those for faecal culture differed if a different cut-off value was chosen for the ELISA. If faecal culture was used for screening in a Danish dairy region where the median ELISA reading was a measure of the general disease situation, the sensitivity of the faecal culture was 20-25%. If faecal culture was used as a confirmatory test on cows with a high ELISA reading (and thus high level of antibodies), the sensitivity of the faecal culture would be in the range 60-70%. These results emphasise the importance of the composition of a target population before selecting a specific diagnostic test for a given purpose. We concluded that faecal culture is useful for confirmation but not for screening purposes. 相似文献
65.
OBJECTIVE: To establish reference values for activated coagulation time (ACT) in cats by use of jugular venipuncture and direct collection of blood into ACT vacuum tubes. ANIMALS: 100 clinically normal cats that were to have elective surgery performed at a private practice. PROCEDURE: Collection of 3 blood samples for ACT measurement was attempted for each cat at the time of elective surgery: sample 1, obtained before sedation; sample 2, tube 1 of 2 consecutive samples obtained from a single venipuncture of the contralateral jugular vein after sedation with acepromazine and ketamine hydrochloride; and sample 3, tube 2 collected immediately following collection of sample 2 without removing the needle from the vein. Venipuncture quality was rated subjectively on a 3-point scale. RESULTS: Median ACT were 95 seconds for each sample group. The middle 95% of values ranged inclusively from 55 to 185 seconds (sample 1), 65 to 135 seconds (sample 2), 45 to 145 seconds (sample 3), and 55 to 165 seconds overall (samples 1, 2, and 3). Significant differences in ACT values were not detected between sample groups. Significant relationships between ACT and venipuncture quality or sex of cat were not detected. CONCLUSIONS AND CLINICAL RELEVANCE: With the ACT protocols used, clinically normal cats had ACT of < 165 seconds. The ACT in cats does not appear to be significantly affected by sex, sedation with acepromazine and ketamine, or by moderately traumatic venipunctures. These results refute widespread statements that ACT should be < 65 seconds in healthy cats. Cats with ACT repeatedly > 165 seconds should be further evaluated for hemostatic disorders. 相似文献
66.
67.
68.
69.
Steiner WR 《Science (New York, N.Y.)》1929,70(1818):413-416
70.
Hans Eschenlohr 《Forstwissenschaftliches Centralblatt》1921,43(10):376-391
Ohne Zusammenfassung 相似文献