全文获取类型
收费全文 | 707篇 |
免费 | 40篇 |
专业分类
林业 | 56篇 |
农学 | 23篇 |
基础科学 | 1篇 |
81篇 | |
综合类 | 74篇 |
农作物 | 9篇 |
水产渔业 | 17篇 |
畜牧兽医 | 438篇 |
园艺 | 2篇 |
植物保护 | 46篇 |
出版年
2023年 | 8篇 |
2022年 | 7篇 |
2021年 | 9篇 |
2019年 | 10篇 |
2018年 | 11篇 |
2017年 | 15篇 |
2016年 | 11篇 |
2015年 | 15篇 |
2014年 | 14篇 |
2013年 | 40篇 |
2012年 | 30篇 |
2011年 | 21篇 |
2010年 | 24篇 |
2009年 | 19篇 |
2008年 | 14篇 |
2007年 | 25篇 |
2006年 | 22篇 |
2005年 | 22篇 |
2004年 | 11篇 |
2003年 | 20篇 |
2002年 | 20篇 |
2001年 | 12篇 |
2000年 | 10篇 |
1999年 | 14篇 |
1997年 | 6篇 |
1996年 | 10篇 |
1993年 | 8篇 |
1992年 | 13篇 |
1991年 | 21篇 |
1990年 | 19篇 |
1989年 | 20篇 |
1988年 | 14篇 |
1987年 | 17篇 |
1986年 | 22篇 |
1985年 | 12篇 |
1984年 | 10篇 |
1983年 | 14篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 9篇 |
1976年 | 6篇 |
1975年 | 8篇 |
1974年 | 11篇 |
1973年 | 9篇 |
1971年 | 10篇 |
1970年 | 8篇 |
1966年 | 11篇 |
1938年 | 6篇 |
排序方式: 共有747条查询结果,搜索用时 15 毫秒
31.
32.
Von H. Karg M. Hartl B. Hoffmann D. Schams W. Schmidt Von O. Günzler E. Huber S. Müller 《Reproduction in domestic animals》1976,11(1):7-18
1. Durch intramuskulare Injektion von 0,5 mg des Prostaglandinanalogs ICI 80 996 beim Rind während der Gelbkörperphase des Zyklus kann nach 15–24 Stunden ein Abfall der Progesteronwerte unter 1 ng/ml Blutplasma und damit eine nachhaltige Luteolyse erreicht werden. Die sich anschließende Brunst ist ovulatorisch und feral. Das Präparat wird ohne Nebenwirkungen vertragen. 2. Durch zweimalige Injektion (d. h. je 1 mal 0,5 mg i. m.) im Abstand von 11 Tagen kann dieser Luteolyseeffekt zu Brunstsynchronisationen herangezogen werden; dabei ist eine Zykluskontrolle oder Brunstbeobachtung nicht erforderlich. 3. in 8 Feldversuchen konnte bei 213 Tieren ein Synchronisationserfolg von 90,6 % und, nach KB in der 1. induzierten Brunst, ein Konzeptionsergebnis von 54,7 % (bzw. von 60,1 %, wenn man die Auswertung auf die erfolgreich synchronisierten Tiere beschränkt) erzielt werden. Die KB bei 119 nicht behandelten Kontrolltieren, die in 5 dieser 8 Versuche zur Verfugung standen, war zu 60,3 % erfolgreich. 4. In einem Problembestand konnte die Fertilitätslage durch das biotechnische Vorgehen der Prostaglandinanwendung unmittelbar nicht verbessert werden 5. Die palpatorischen Ovarbefunde zum Zeitpunkt der KB ergaben, daß Tiere mit aprungbereiten Follikeln'zu 65 %, mit kleinen, nicht reifen Follikeln zu 50,8 % und mit bereitsgesprungenen Follikeln zu 15,8 % konzipierten. 6. Die bei einem Teil der Versuche eingesetzte zusdtzliche Behandlung mit 1,0 bzw. 1,5 mg des Gonadotropin-Releasinghormons (LRH-Hoechst 471) i. m. zum Zeitpunkt der Besamung zeigte bezüglich des Konzeptionsergebnisses eine positive Tendenz. 相似文献
33.
34.
35.
Hoffmann B Strauch E Appel B Nattermann H 《Berliner und Münchener tier?rztliche Wochenschrift》2002,115(5-6):189-194
The human pathogenic strains of Yersinia harbour a conserved plasmid carrying the Yop virulon. The virulence plasmid of Yersinia enterocolitica strains belonging to the serogroups O:3 and O:9 were used as probes to detect homologous sequences in plasmids of "avirulent" Yersinia strains. "Avirulent" Yersinia strains (Y. enterocolitica biogroup 1A, Y. intermedia, Y. kristensenii and Y. frederiksenii) lack the virulence plasmid. They are widely distributed in the environment and can frequently be isolated from clinical samples. Hybridisation experiments revealed a number of common genetic elements of the virulence plasmid and the plasmids of "avirulent" Yersinia strains. These elements were identified as genes involved in plasmid replication, as an endonuclease gene and as mobile genetic elements. However, none of the plasmid encoded virulence genes was present in the plasmids of "avirulent" Yersinia strains. The frequent occurrence and the possible etiological relevance of "avirulent" isolates will be discussed. 相似文献
36.
Apart from estrone-3-sulfate (E1S) the bovine placenta produces progesterone (P4), though the corpus luteum is the major source of P4 responsible for maintaining pregnancy. So far the biological function of placental steroids in cattle is largely unknown. However, since the local availability of free estrone (E1) in the placenta seems to be controlled by sulfatase and sulfotranferase, the hypothesis was developed that placental estrogens and P4 might act as local regulatory factors. To test for such a function placentomes from 150, 220, 240, 270 days (D) pregnant and parturient cows were screened immunohistochemically for progesterone and estrogen receptors (PR, ER). PR were found at all stages in the caruncle in stromal cells and capillary pericytes but only at parturition in arterial walls. Percentage of PR-positive caruncular stromal cells (CSC) increased (P<0.05) from 51.8+/-2.6% at D150 to 58.9+/-1.8% at parturition. ER were detected in CSC, caruncular epithelial (CE) cells and in caruncular capillary pericytes. Mean percentage of ER-positive CSC decreased from 39.0+/-5.9% in pregnant cows to 17.5+/-8.3% at parturition (P<0.05). In CE all cells exhibited positive signals with the exception of those immediately surrounding large primary chorionic villi. Proliferation was assessed immunohistochemically by determining the percentage of Ki67-antigen positive cells. Highest values (P<0.001) were obtained for CE (58.0-68.3%), followed by the trophoblast (23.3-25.4%), CSC (10.6-45.3%) and the stroma of the chorionic villi (2.9-10.5%). A transient depression of proliferation in CSC between D150-270 (P<0.05) paralleled local estrogen tissue concentrations. The results suggest that placental estrogens and P4 are important factors controlling caruncular growth, differentiation and function. 相似文献
37.
Prognostic significance of serum alkaline phosphatase activity in canine appendicular osteosarcoma 总被引:3,自引:0,他引:3
Garzotto CK Berg J Hoffmann WE Rand WM 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2000,14(6):587-592
Sixty-one dogs with appendicular osteosarcoma were treated with amputation and chemotherapy of cisplatin and doxorubicin. Serum samples were obtained before and after treatment for determination of total alkaline phosphatase (TALP) activity as well as the activities of the constituent bone (BALP), liver (LALP), and corticosteroid-induced (CALP) isoenzymes. The relationship between alkaline phosphatase activities and survival was examined by Cox proportional hazards regression analysis and Kaplan-Meier log rank analysis. Mean activity of TALP, BALP, and LALP decreased significantly after treatment (P < .001). TALP and LALP activities before treatment were significantly correlated with survival (P = .006 and .001, respectively). The correlation between BALP activity before treatment and survival approached significance (P = .054). CALP activity and TALP, BALP, and LALP activities after treatment were not significantly correlated with survival. Dogs with normal pretreatment TALP and BALP activities survived significantly longer than dogs with increased pretreatment activities (P = .001 and .003, respectively). Median survival times for dogs with normal or increased TALP activities before treatment were 12.5 and 5.5 months, respectively; and median survival times for dogs with normal or increased BALP activities before treatment were 16.6 and 9.5 months, respectively. In the design of future clinical trials involving dogs with osteosarcoma, consideration should be given to stratifying the randomization according to alkaline phosphatase activity. In addition, alkaline phosphatase activity should be a factor considered by clinicians attempting to tailor the aggressiveness of adjuvant chemotherapy to the needs of individual patients or owners. 相似文献
38.
Ultrasonography is important in the clinical examination of the foal. The ultrasonographic appearance and size of the neonatal kidneys were defined and an imaging protocol established in 6 normal Thoroughbred foals (mean age +/- s.d. 5.0 +/- 3.2 days). Characteristically, in both the heart-shaped right kidney and bean-shaped left kidney, the renal cortex was more echogenic than the medulla. The terminal recesses, renal crest and pelvis were identified, as was the ureter, which contained anechoic urine in its lumen. The renal, interlobar and arcuate vessels were seen. For the right kidney, the ultrasonographic probe was placed at the 14-17th intercostal spaces and paralumbar fossa. For the left kidney, the probe was at the 16th or 17th intercostal spaces and paralumbar fossa. Perirenal structures, including the caudate lobe of the liver, the dorsal extremity of the spleen, the adrenals, the aorta and caudal vena cava were also identified. An understanding of the ultrasonographic appearance of the normal neonatal kidney, accompanied by a routine imaging protocol to ensure that all regions of each kidney are examined, permit a more informed interpretation of renal images in the first few days postpartum. 相似文献
39.
Efficacy of long-acting oxytetracycline alone or combined with streptomycin in the treatment of bovine brucellosis 总被引:1,自引:0,他引:1
P Nicoletti F W Milward E Hoffmann L Altvater 《Journal of the American Veterinary Medical Association》1985,187(5):493-495
Twenty-nine Brucella abortus culture-positive cows were treated with a long-acting oxytetracycline (20 mg/kg of body weight, IM) alone or combined with streptomycin (25 mg/kg, IM or IV) or were re-treated with the same product. There appeared to be a synergism by the 2 drugs. Of 21 courses of treatment with the combined antibiotics, 14 (67%) were considered successful. Only 3 of 14 (21%) were successful using oxytetracycline alone. The period from onset of therapy to cessation of shedding in udder secretions was variable. Four cows that ceased shedding were culture-positive in tissues taken at slaughter. The titers on tube agglutination and complement-fixation tests were of limited value in short-term evaluations of therapeutic regimens. 相似文献
40.