全文获取类型
收费全文 | 768篇 |
免费 | 40篇 |
专业分类
林业 | 79篇 |
农学 | 15篇 |
基础科学 | 4篇 |
107篇 | |
综合类 | 121篇 |
农作物 | 17篇 |
水产渔业 | 29篇 |
畜牧兽医 | 372篇 |
园艺 | 5篇 |
植物保护 | 59篇 |
出版年
2020年 | 7篇 |
2019年 | 14篇 |
2018年 | 14篇 |
2017年 | 8篇 |
2016年 | 18篇 |
2015年 | 10篇 |
2014年 | 16篇 |
2013年 | 22篇 |
2012年 | 20篇 |
2011年 | 40篇 |
2010年 | 20篇 |
2009年 | 17篇 |
2008年 | 24篇 |
2007年 | 27篇 |
2006年 | 20篇 |
2005年 | 17篇 |
2004年 | 24篇 |
2003年 | 23篇 |
2002年 | 23篇 |
2001年 | 21篇 |
2000年 | 10篇 |
1999年 | 19篇 |
1998年 | 15篇 |
1996年 | 8篇 |
1995年 | 12篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 15篇 |
1991年 | 13篇 |
1990年 | 16篇 |
1989年 | 16篇 |
1988年 | 17篇 |
1987年 | 13篇 |
1986年 | 10篇 |
1985年 | 22篇 |
1984年 | 7篇 |
1982年 | 7篇 |
1979年 | 10篇 |
1978年 | 10篇 |
1977年 | 7篇 |
1975年 | 12篇 |
1974年 | 16篇 |
1973年 | 12篇 |
1972年 | 7篇 |
1971年 | 16篇 |
1970年 | 7篇 |
1969年 | 18篇 |
1968年 | 6篇 |
1967年 | 15篇 |
1965年 | 7篇 |
排序方式: 共有808条查询结果,搜索用时 0 毫秒
1.
2.
H. Schneider 《Forstwissenschaftliches Centralblatt》1938,60(11):358-360
Ohne Zusammenfassung 相似文献
3.
Dr. Adolf Herfs 《Journal of pest science》1936,12(12):137-142
Ohne Zusammenfassung
Mit 19 Abbildungen. 相似文献
4.
Dr. Adolf Müller 《Journal of pest science》1926,2(3):25-29
Ohne Zusammenfassung
Mit 3 Abbildungen. 相似文献
5.
Analysis of caprine IgG1 and IgG2 subclass responses to Chlamydia psittaci infection and vaccination
N Schmeer H Krauss J Apel M Adami H P Müller W Schneider J A Perez-Martinez H Rieser 《Veterinary microbiology》1987,14(2):125-135
Enzyme-linked immunosorbent assays (ELISAs) specific for caprine IgG(H+L), IgG1 and IgG2 were developed and evaluated for serodiagnosis of Chlamydia psittaci infections in a Tunisian goat flock with currently occurring chlamydial abortions and a clinically inapparent goat flock of an animal research facility. Additionally, ELISAs were applied to record the IgG1 and IgG2 dynamics of four goats vaccinated with inactivated Chlamydia psittaci and Coxiella burnetii. For screening purposes, the IgG(H+L) ELISA proved to be superior to the complement fixation test because it detected a larger number of chlamydial abortions and was easier to perform and to interpret. Analysis of Chlamydia psittaci-specific IgG1 and IgG2 responses to naturally occurring infections by ELISA revealed high IgG1 levels associated with IgG2 in goats with current abortions, whereas clinically inapparent, but seropositive goats were characterized by significantly lower IgG1 levels only (P less than 0.001). Similarly, the four vaccinated goats responded initially with Chlamydia psittaci-specific IgG1, whereas second and third vaccinations induced (as in goats with chlamydial abortions) predominantly IgG1, but also IgG2. The results indicated that clinically inapparent chlamydial infection may be distinguished from overt disease by analysing specific IgG1 and IgG2 responses. Applying Coxiella burnetii- specific ELISAs on field samples, IgG1 alone could be detected in eight, IgG2 alone in one and IgG1 combined with IgG2 in nine goats. The coxiella-specific antibody response of the four vaccinated goats was--in contrast to the chlamydia-specific response--characterized by IgG2 dominance. 相似文献
6.
7.
Schneider M Hildebrandt N Schweigl T Wehner M 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2007,21(2):251-257
BACKGROUND: Patent ductus arteriosus (PDA) size and morphology influence the selection of the kind and the size of the embolization device used to effect shunt closure. HYPOTHESIS: That echocardiographic measurement of PDA in dogs is accurate. ANIMALS: Forty-five client-owned dogs with PDA. METHODS: Prospective observational study. Echocardiographic and angiographic data were compared. RESULTS: Measurement of the ductus in color Doppler echocardiography (CD-E) and 2-dimensional echocardiography (2D-E) was achieved from left parasternal views in 43 of 45 unsedated dogs (96%). In these 43 dogs, the angiographic minimal PDA diameter was 3.72 +/- 1.59 mm, and the diameter of the PDA ampulla was 8.46 +/- 3.01 mm. The CD-E minimal PDA diameter ranged from 2.3 to 9.5 mm (median, 4.0 mm). There was a significant mean difference to the angiographic measurements (1.15 +/- 0.95 mm; P < .0001). An agreement in a 1-mm range was found in 21 of 43 dogs (48%). The 2D-E minimal PDA diameter was 3.73 +/- 1.78 mm, and the mean difference to the angiographic measurements was not significant (0.00 +/- 0.72 mm; P = .98). An agreement in a 1-mm range was found in 31 of 43 dogs (72%). The 2D-E measurement of the PDA ampulla revealed a significant mean difference to the angiographic data (1.95 +/- 2.43 mm, P < .0001). An agreement in a 2-mm range was found in 21 of 43 dogs (49%). CONCLUSIONS AND CLINICAL IMPORTANCE: The 2D-E from the left cranial parasternal view is an excellent noninvasive method to estimate the PDA minimal diameter before doing catheter intervention. 相似文献
8.
Role of transpiration suppression by evaporation of intercepted water in improving irrigation efficiency 总被引:9,自引:0,他引:9
J. A. Tolk T. A. Howell J. L. Steiner D. R. Krieg A. D. Schneider 《Irrigation Science》1995,16(2):89-95
Sprinkler irrigation efficiency declines when applied water intercepted by the crop foliage, or gross interception (Igross), as well as airborne droplets and ponded water at the soil surface evaporate before use by the crop. However, evaporation of applied water can also supply some of the atmospheric demands usually met by plant transpiration. Any suppression of crop transpiration from the irrigated area as compared to a non-irrigated area can be subtracted from Igross irrigation application losses for a reduced, or net, interception (Inet) loss. This study was conducted to determine the extent in which transpiration suppression due to microclimatic modification resulting from evaporation of plant-intercepted water and/or of applied water can reduce total sprinkler irrigation application losses of impact sprinkler and low energy precision application (LEPA) irrigation systems. Fully irrigated corn (Zea Mays L.) was grown on 0.75 m wide east-west rows in 1990 at Bushland, TX in two contiguous 5-ha fields, each containing a weighing lysimeter and micrometeorological instrumentation. Transpiration (Tr) was measured using heat balance sap flow gauges. During and following an impact sprinkler irrigation, within-canopy vapor pressure deficit and canopy temperature declined sharply due to canopyintercepted water and microclimatic modification from evaporation. For an average day time impact irrigation application of 21 mm, estimated average Igross loss was 10.7%, but the resulting suppression of measured Tr by 50% or more during the irrigation reduced Igross loss by 3.9%. On days of high solar radiation, continued transpiration suppression following the irrigation reduced Igross loss an additional 1.2%. Further 4–6% reductions in Igross losses were predicted when aerodynamic and canopy resistances were considered. Irrigation water applied only at the soil surface by LEPA irrigation had little effect on the microclimate within the canopy and consequently on Tr or ET, or irrigation application efficiency. 相似文献
9.
Various types of trap-tubs were tested both under controlled conditions in standardised trial series and in the field. New trap-tubs were poorly accepted by the animals, whereas weathered tubs were readily accepted within a very short period of time. The trapping mechanisms of tubs used in Lower Saxony and improved tubs in Hesse were both found to be suitable. The trapping method proved to be highly selective since long-tailed mice (Apodemus spp.) can easily escape by jumping onto the edge of the tub. Voles (Microtus agrestis, Clethrionomys glareolus) explored the inside of the tub and worked its exits with decreasing intensity during the time of captivity. They died of hypothermia within a few hours. Elimination of the trapped rodents by their natural enemies was not observed. The trials showed that trap-tubs are suitable for selective reduction of the density of field voles and red-backed voles in forests. The results also contribute to assessing the humaneness of the control method. 相似文献
10.
In a feeding experiment (54 piglets) and a slaughtering test for the registration of tract and digesta properties (15 piglets) the influence of rations with 69% rye (R) or wheat (W) with and without a supplement of 200 mg of the chinoxalin derivate Bisergon/kg DM (rations RB and WB) was studied. In the sequence R, RB, W and WB the feed intake in the test period of 3 weeks after weaning amounted to 581, 651, 583 and 764 g, weight gain to 314, 365, 319 and 424 g per animal and day. In the same sequence the concentration of organic acids in the stomach amounted to 41, 5, 25 and 18 mmol per 100 g dry matter and in the colon to 106, 83, 64 and 62. Bisergon caused a redistribution of the digesta from the stomach to the large intestine and a more rapid emptying of the stomach as well. Rye caused extreme fermentation processes in the front part of the tract and Bisergon clearly has ergotropic qualities for the stabilization of the intestinal flora. 相似文献