全文获取类型
收费全文 | 513篇 |
免费 | 25篇 |
专业分类
林业 | 80篇 |
农学 | 5篇 |
基础科学 | 2篇 |
39篇 | |
综合类 | 93篇 |
农作物 | 6篇 |
水产渔业 | 27篇 |
畜牧兽医 | 279篇 |
园艺 | 2篇 |
植物保护 | 5篇 |
出版年
2019年 | 6篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2013年 | 18篇 |
2012年 | 15篇 |
2011年 | 9篇 |
2010年 | 9篇 |
2009年 | 20篇 |
2008年 | 20篇 |
2007年 | 7篇 |
2006年 | 18篇 |
2005年 | 8篇 |
2004年 | 16篇 |
2003年 | 14篇 |
2002年 | 14篇 |
2001年 | 15篇 |
2000年 | 8篇 |
1999年 | 10篇 |
1998年 | 18篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1993年 | 10篇 |
1992年 | 18篇 |
1991年 | 15篇 |
1990年 | 16篇 |
1989年 | 11篇 |
1988年 | 13篇 |
1987年 | 11篇 |
1986年 | 13篇 |
1985年 | 7篇 |
1984年 | 11篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1978年 | 4篇 |
1976年 | 5篇 |
1974年 | 4篇 |
1973年 | 6篇 |
1972年 | 6篇 |
1916年 | 4篇 |
1871年 | 4篇 |
1869年 | 6篇 |
1868年 | 7篇 |
1867年 | 9篇 |
1866年 | 5篇 |
1864年 | 4篇 |
1863年 | 8篇 |
1859年 | 4篇 |
排序方式: 共有538条查询结果,搜索用时 15 毫秒
91.
The demography of bovine infections caused by Mycobacterium avium subspecies paratuberculosis (MAP) in Ireland is poorly defined. The objective of this study was to describe the demographics of cattle positive to MAP on faecal culture, based on submissions to the Cork Regional Veterinary Laboratory (Cork RVL) from 1994 to 2006. The study focused on all available faecal samples from adult cattle with non-responsive chronic diarrhoea that were submitted by private veterinary practitioners to Cork RVL for MAP culture. For each MAP-positive by faecal culture animal, data were collated from Cork RVL and Cattle Movement Monitoring Scheme (CMMS) records. Johne's disease (JD) was confirmed in 110 animals from 86 herds by the Cork RVL between 1994 and 2006, with a rate of positive cases between 15% and 18% over last four years of the study. Two breeds (Holstein/Friesian or Limousin) made up 78% of submissions. Movements were assessed for the 57 study animals with available movement information, 90% died within one year of the test and 26% tested positive in the herd they were born into. The study provides preliminary information about movement trends and demographics of animals with MAP positive submissions. Although the study area is restricted, it includes the most intensive (and economically-important) dairy region in Ireland. The demographics of JD infection from the study area are in agreement with international reports. Further work is required to determine demographic trends, incidence and prevalence of JD throughout Ireland. It is hoped this work may contribute to the development of a surveillance strategy for MAP by regional veterinary laboratories. 相似文献
92.
Foss A Grimsbø E Vikingstad E Nortvedt R Slinde E Roth B 《Fish physiology and biochemistry》2012,38(2):565-571
Investigation of the physiological effects of live chilling in Atlantic salmon, Salmo salar, has been performed in two experiments. In the first, fish (mean weight 840 g) acclimatized to either 16, 8, or 4°C were
directly transferred horizontally or vertically (9 combinations) to water temperatures of 16, 8, 4, or 0°C using a dip net.
Blood samples were collected at 1 and 6 h (h) post-transfer. In the second experiment, fish (mean weight 916 g) acclimatized
to 16°C were exposed to four temperature-drop regimes (no physical handling): 16–4°C (over 5 h), 16–4°C (over 1 h), 16–0°C
(over 5 h), and 16–0°C (over 1 h). Blood samples were collected 1 h post-temperature drop. Physical transfers in the first
trial, i.e., temperature drops, resulted in immediate (1 h) increases in blood lactate concentrations at all three temperatures,
but levels were significantly reduced and close to pre-transfer levels after 6 h. Horizontal transfers, i.e., 16–16°C, 8–8°C,
and 4–4°C, resulted in similar increases and were not significantly different from the groups exposed to temperature drops.
The most severe vertical transfer (16-0) resulted in a swift loss of equilibrium and eventually death. In experiment 2, temperature
drops from 16 to 4°C and from 16 to 0°C over a period of one or 5 h, without physically handling the fish, resulted in no
significant increases in any of the measured parameters 1 h post-transfer, except in the 16–0 (1 h) group. The latter experienced
a significant increase in blood sodium, glucose, lactate, and cortisol levels compared to all other groups. The results suggest
that salmon are capable of tolerating relatively steep temperature drops without any significant negative effects on blood
stress parameters and that physical stress from handling overrides the effect of thermal insults. 相似文献
93.
HY Jang SJ Ji YH Kim HY Lee JS Shin HT Cheong JT Kim IC Park HS Kong CK Park BK Yang 《Reproduction in domestic animals》2010,45(6):967-974
The aim of the present study was to elucidate the fundamental mechanism of bovine oviduct epithelial cell (BOEC) co‐culture on developmental capacity of bovine in vitro oocyte maturation/in vitro fertilization (IVM/IVF) embryos. We examined the effects of astaxanthin against nitric oxide‐induced oxidative stress on cell viability by MTT assay, lipid peroxidation (LPO) by using thiobarbituric acid (TBA) reaction for malondialdehyde (MDA) and the expression of antioxidant genes (CuZnSOD, MnSOD and Catalase) or apoptosis genes (Bcl‐2, Caspase‐3 and Bax) by RT‐PCR in BOEC. We also evaluated the developmental rates of bovine IVM/IVF embryos co‐cultured with BOEC pre‐treated with astaxanthin (500 μm ) in the presence or absence of sodium nitroprusside (SNP, 1000 μm ) for 24 h. Cell viability in BOEC treated with SNP (50–2000 μm ) lowered, while astaxanthin addition (50–500 μm ) increased it in a dose‐dependent manner. Cell viability in astaxanthin plus SNP (1000 μm ) gradually recovered according to the increase in astaxanthin additions (100–500 mm ). The LPO in astaxanthin group (50–500 μM) gradually decreased in a dose dependent manner and among SNP or astaxanthin plus SNP group, SNP alone and astaxanthin (50 μM) plus SNP shown a significant increase than other groups (p < 0.05). Expression of apoptosis or antioxidant genes was detected by RT‐PCR. Bcl‐2 and antioxidant genes were detected in astaxanthin or astaxanthin plus SNP group, and Caspase‐3 and Bax genes were only found in SNP group. When bovine IVM/IVF embryos were cultured for 6–7 days under co‐culture system such as BOEC treated with astaxanthin in the presence or absence of SNP, the developmental ability to blastocysts in 500 μm astaxanthin group was the highest of all groups. These results suggest that astaxanthin has a antioxidative effect on cell viability and LPO of BOEC, and development of bovine IVM/IVF embryos due to the induction of antioxidant genes and suppression of apoptosis genes. 相似文献
94.
95.
M. Abdalla K. Rueangritsarakul M. Jones B. Osborne M. Helmy B. Roth J. Burke P. Nolan P. Smith M. Williams 《Water, air, and soil pollution》2012,223(8):5155-5174
Field management is expected to influence nitrous oxide (N2O) production from arable cropping systems through effects on soil physics and biology. Measurements of N2O flux were carried out on a weekly basis from April 2008 to August 2009 for a spring sown barley crop at Oak Park Research Centre, Carlow, Ireland. The soil was a free draining sandy loam typical of the majority of cereal growing land in Ireland. The aims of this study were to investigate the suitability of combining reduced tillage and a mustard cover crop (RT?CCC) to mitigate nitrous oxide emissions from arable soils and to validate the DeNitrification?CDeComposition (DNDC) model version (v. 9.2) for estimating N2O emissions. In addition, the model was used to simulate N2O emissions for two sets of future climate scenarios (period 2021?C2060). Field results showed that although the daily emissions were significantly higher for RT?CCC on two occasions (p?<?0.05), no significant effect (p?>?0.05) on the cumulative N2O flux, compared with the CT treatment, was found. DNDC was validated using N2O data collected from this study in combination with previously collected data and shown to be suitable for estimating N2O emissions (r 2?=?0.70), water-filled pore space (WFPS) (r 2?=?0.58) and soil temperature (r 2?=?0.87) from this field. The relative deviations of the simulated to the measured N2O values with the 140?kg N ha?1 fertiliser application rate were ?36?% for RT?CCC and ?19?% for CT. Root mean square error values were 0.014 and 0.007?kg N2O?CN ha?1 day?1, respectively, indicating a reasonable fit. Future cumulative N2O fluxes and total denitrification were predicted to increase under the RT?CCC management for all future climate projections, whilst predictions were inconsistent under the CT. Our study suggests that the use of RT?CCC as an alternative farm management system for spring barley, if the sole objective is to reduce N2O emissions, may not be successful. 相似文献
96.
Lina Bernaola Molly Darlington Kadie Britt Patricia Prade Morgan Roth Adrian Pekarcik Michelle Boone Dylan Ricke Anh Tran Joanie King Kelly Carruthers Morgan Thompson John J Ternest Sarah E Anderson Scott W Gula Kayleigh C Hauri Jacob R Pecenka Sajjan Grover Heena Puri Surabhi Gupta Vakil 《Journal of insect science (Online)》2021,21(2)
The 2020 Student Debates of the Entomological Society of America (ESA) were live-streamed during the Virtual Annual Meeting to debate current, prominent entomological issues of interest to members. The Student Debates Subcommittee of the National ESA Student Affairs Committee coordinated the student efforts throughout the year and hosted the live event. This year, four unbiased introductory speakers provided background for each debate topic while four multi-university teams were each assigned a debate topic under the theme ‘Technological Advances to Address Current Issues in Entomology’. The two debate topics selected were as follows: 1) What is the best taxonomic approach to identify and classify insects? and 2) What is the best current technology to address the locust swarms worldwide? Unbiased introduction speakers and debate teams began preparing approximately six months before the live event. During the live event, teams shared their critical thinking and practiced communication skills by defending their positions on either taxonomical identification and classification of insects or managing the damaging outbreaks of locusts in crops. 相似文献
97.
98.
Direct observation of washed conidia of Cylindrocladium scoparium on non-sterile soils, air dried and rewetted immediately before deposition of conidia, indicated that peak germination (33–58%) occurred after 24 h incubation at 26°C. Peak germination on continually moist soils was lower (18–26%) than on rewetted soils. Lysis of germ tubes and germinating conidia on continually moist soils at 26°C was evident with 48 h. Conidia did not germinate on continually moist soils at 6°C and lysis did not become apparent until 168 h. Conidia germinated at a high level (93–99%) in axenic culture in the absence of exogenous C and N sources. The inhibition of conidial germination on soils may be attributed, in part, to the presence of soil volatiles. Germination of conidia placed on washed agar disks and exposed to volatiles from four soils ranged from 51 to 86% of the no-soil controls. Addition of carbon (13 ng C per conidium as glucose) and nitrogen (65 pg N ng?1 C as NH4C1) nullified the inhibitory effect of the soil volatiles. Germinability assayed on a selective medium at 26°C of conidia in artificially infested soils (approximately 104 conidia g?1 soil) decreased progressively during incubation at 26°C from 1 week to 4 months. No germinable conidia were recovered from artificially infested soils after 2 months incubation at 6°C. Conidia of C. floridanum and C. crotalariae responded similarly to C. scoparium in many assays. 相似文献
99.
100.