全文获取类型
收费全文 | 209篇 |
免费 | 12篇 |
专业分类
林业 | 15篇 |
基础科学 | 1篇 |
44篇 | |
综合类 | 40篇 |
农作物 | 3篇 |
水产渔业 | 7篇 |
畜牧兽医 | 92篇 |
园艺 | 5篇 |
植物保护 | 14篇 |
出版年
2022年 | 2篇 |
2019年 | 5篇 |
2018年 | 8篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 2篇 |
2014年 | 9篇 |
2013年 | 11篇 |
2012年 | 6篇 |
2011年 | 9篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 13篇 |
2007年 | 5篇 |
2006年 | 13篇 |
2005年 | 5篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1991年 | 3篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1979年 | 2篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1970年 | 4篇 |
1969年 | 3篇 |
1968年 | 5篇 |
1966年 | 6篇 |
1948年 | 3篇 |
1942年 | 1篇 |
1941年 | 2篇 |
1939年 | 1篇 |
排序方式: 共有221条查询结果,搜索用时 15 毫秒
1.
2.
3.
Gerald L. Schroeder 《Aquaculture (Amsterdam, Netherlands)》1978,14(4):303-325
Intensely-manured ponds produce 15–30 kg fish ha?1 day?1 with cow or chicken manure and nitrogen- and phosphate-rich fertilizers as the only nutritional inputs. The manure as it is supplied to the ponds is not a good fish food and does not produce good fish growth. Quantitative analysis shows that the production of all organisms, autotrophic and heterotrophic, pelagic and benthic, large enough to be used directly by the fish (i.e., larger than 37 microns) is adequate to account for less than half of the measured fish growth. Production within the microbial community that flourishes on and rapidly digests the manure organic matter is adequate to produce the measured fish growth. The fish appear to harvest the microorganisms at the level of bacteria and protozoa, by ingesting the small straw-like particles which comprise much of the manure and serve as the substrate for the microbial growth. 相似文献
4.
Antoine LF Gady Freddy WK Hermans Marion HBJ Van de Wal Eibertus N van Loo Richard GF Visser Christian WB Bachem 《Plant methods》2009,5(1):13-14
Background
The establishment of mutant populations together with the strategies for targeted mutation detection has been applied successfully to a large number of organisms including many species in the plant kingdom. Considerable efforts have been invested into research on tomato as a model for berry-fruit plants. With the progress of the tomato sequencing project, reverse genetics becomes an obvious and achievable goal. 相似文献5.
6.
7.
Jane C.F. Chang Paul Ciaccio Patricia Schroeder Lindsay Wright Russell Westwood Anna-Lena Berg 《Journal of toxicologic pathology》2014,27(1):31-42
AZD3783, a cationic amphiphilic drug and a potent inhibitor of the 5-hydroxytryptamine
(5-HT1B) receptor, was explored as a potential treatment for depression. To
support clinical trials, repeat dose toxicity studies in rats and dogs were conducted.
Here we report toxicity findings in dogs after dosing from 1 to 3 months. In the 1-month
study, there were minimal neuronal vacuolation in the brain, a marked increase in liver
enzymes accompanied by hepatocellular degeneration/necrosis and phospholipidosis (PLD),
and PLD/cholecystitis in the gallbladder of animals dosed at 47 mg/kg/day. In the 3-month
study, neurotoxicity resulted in euthanasia of one animal dosed at 30 mg/kg/day after 86
days. Extensive pathologic changes were seen in all animals in retina epithelium
(inclusion bodies), brain (neuronal vacuolation, degeneration, or necrosis and nerve fiber
degeneration), spinal ganglia (vacuolation, degeneration, or necrosis), as well as sciatic
and optic nerves (degeneration). Pigment-laden macrophages were observed in the lung,
kidney, liver, gallbladder, bone marrow, gastrointestinal tract, and lymphoid tissues.
Also seen were vitrel and retinal hemorrhage in the eyes. A brain concentration and
pathology study showed that the concentration of AZD3783 in the brain was approximately 4
times higher than in the plasma after 4 weeks of dosing, however, they were similar in all
regions examined, and did not correlate with areas with pathologic findings. Our findings
with AZD3783 in dogs have not been reported previously with other CNS compounds that
effect through serotonergic pharmacology. 相似文献
8.
AM Batista WA Gomes CCD Carvalho PLJ Monteiro Jr FLM Silva FC Almeida PC Soares GF Carneiro MMP Guerra 《Reproduction in domestic animals》2014,49(3):476-480
The aim of this study was to evaluate the effect of leptin administration during superovulation on in vivo goat embryo production. Ten mature does were superovulated with 133 mg follicle‐stimulating hormone (FSH) i.m. in six descending doses at 12‐h intervals. The goats received 4.8 μg/kg human recombinant leptin s.c. (leptin group, n = 5) or phosphate‐buffered saline (PBS) (control group, n = 5) with the first and second FSH doses. The does were mated and subjected to embryo collection by transcervical technique 6 days later. The total number of cells per embryo and the number of cells with fragmented DNA were assessed in selected blastocysts by combining Hoechst 33342 and terminal dUTP nick‐end labelling (TUNEL) staining. Plasma concentrations of oestradiol (E2) and progesterone (P4) were determined by electrochemiluminescence from the day of FSH treatment, on the day of superovulatory oestrus and on the day before embryo collection. Compared with the control group, the does that received leptin had a higher number of transferable embryos (p < 0.005), fewer embryos classified as degenerated (p < 0.001) and fewer TUNEL‐positive cells/blastocyst (p < 0.001). The number of transferable embryos was positively correlated with E2 concentrations on day of oestrus (r = 0.562; p < 0.01) and P4 concentrations on the day of embryo collection (r = 0.912; p < 0.001). We concluded that in vivo leptin administration during FSH treatment improved embryo quality and affected ovarian steroidogenesis in superovulated goats. 相似文献
9.
R Kasimanickam S Schroeder M Assay V Kasimanickam DA Moore JM Gay WD Whittier 《Reproduction in domestic animals》2014,49(5):775-782
The objectives were (i) to evaluate the effect of temperament, determined by modified 2‐point chute exit and gait score, on artificial insemination (AI) pregnancy rates in beef heifers following fixed time AI and (ii) to determine the effect of temperament on cortisol, substance‐P, prolactin and progesterone at initiation of synchronization and at the time of AI. Angus beef heifers (n = 967) at eight locations were included in this study. At the initiation of synchronization (Day 0 = initiation of synchronization), all heifers received a body condition score (BCS), and temperament score (0 = calm; slow exit and walk or 1 = excitable; fast exit or jump or trot or run). Blood samples were collected from a sub‐population of heifers (n = 86) at both synchronization initiation and the time of AI to determine the differences in serum progesterone, cortisol, prolactin and substance‐P concentrations between temperament groups. Heifers were synchronized with 5‐day CO‐Synch+ controlled internal drug release (CIDR) protocol and were inseminated at 56 h after CIDR removal. Heifers were examined for pregnancy by ultrasound 70 days after AI to determine AI pregnancy. Controlling for synchronization treatment (p = 0.03), facility design (p = 0.05), and cattle handling facility design by temperament score interaction (p = 0.02), the AI pregnancy differed between heifers with excitable and calm temperament (51.9% vs 60.3%; p = 0.01). The alley‐way with acute bends and turns, and long straight alley‐way had lower AI pregnancy rate than did the semicircular alley‐way (53.5%, 56.3% and 67.0% respectively; p = 0.05). The serum hormone concentrations differed significantly between different types of cattle handling facility (p < 0.05). The cattle handling facility design by temperament group interactions significantly influenced progesterone (p = 0.01), cortisol (p = 0.01), prolactin (p = 0.02) and substance‐P (p = 0.04) both at the initiation of synchronization and at the time of AI. Inter‐ and intra‐rater agreement for temperament scoring were moderate and good (Kappa = 0.596 ± 0.07 and 0.797 ± 0.11) respectively. The predictive value for calm and pregnant to AI was 0.87, and excited and non‐pregnant to AI was 0.76. In conclusion, the modified 2‐point temperament scoring method can be used to identify heifers with excitable temperament. Heifers with excitable temperament had lower AI pregnancy. Further, cattle handling facility design influenced the temperament and AI pregnancy. 相似文献
10.
Gerald L. Schroeder 《Aquaculture (Amsterdam, Netherlands)》1983,30(1-4):203-210
The natural isotopic ratio of 13C/12C (reported as δ C) in plant matter varies predictably among plant types. The isotopic ratio of an animal body reflects the isotopic ratio of the feed metabolized. By selecting inputs to an aquaculture feeding and/or fertilization system such that the components have significantly different δ C values, the relative meta-bolization of each of these inputs by the fish can be measured.
In tank-grown Tilapia aurea (δ C = −17), supplied feed (δ C = −18) provided the carbon incorporated into the fish body even though between feedings the fish consumed large quantities of algae (δ C = −22). In penaeid (δ C = −12) grow-out ponds, δ C analyses indicated that selected components of the feed pellet (average δC = −17; components: corn and sorghum δ C −12, soybeans δ C −25) were metabolized, while the benthic natural foods and other bottom organic matter (δ C = −21) provided little or no input. The value of such information for pond management and nutrition studies is clear. 相似文献