全文获取类型
收费全文 | 837篇 |
免费 | 45篇 |
国内免费 | 9篇 |
专业分类
林业 | 380篇 |
农学 | 13篇 |
基础科学 | 3篇 |
72篇 | |
综合类 | 42篇 |
农作物 | 36篇 |
水产渔业 | 32篇 |
畜牧兽医 | 226篇 |
园艺 | 13篇 |
植物保护 | 74篇 |
出版年
2021年 | 14篇 |
2020年 | 9篇 |
2019年 | 9篇 |
2018年 | 17篇 |
2017年 | 17篇 |
2016年 | 19篇 |
2015年 | 20篇 |
2014年 | 22篇 |
2013年 | 25篇 |
2012年 | 18篇 |
2011年 | 23篇 |
2010年 | 14篇 |
2009年 | 13篇 |
2008年 | 18篇 |
2007年 | 21篇 |
2006年 | 18篇 |
2005年 | 20篇 |
2004年 | 12篇 |
2003年 | 19篇 |
2002年 | 24篇 |
2001年 | 16篇 |
2000年 | 16篇 |
1999年 | 9篇 |
1996年 | 7篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1986年 | 8篇 |
1973年 | 9篇 |
1972年 | 9篇 |
1971年 | 9篇 |
1968年 | 6篇 |
1965年 | 8篇 |
1961年 | 6篇 |
1956年 | 8篇 |
1938年 | 6篇 |
1934年 | 18篇 |
1932年 | 9篇 |
1931年 | 6篇 |
1870年 | 12篇 |
1868年 | 14篇 |
1867年 | 16篇 |
1866年 | 19篇 |
1865年 | 27篇 |
1864年 | 16篇 |
1863年 | 17篇 |
1862年 | 14篇 |
1860年 | 6篇 |
1858年 | 9篇 |
1857年 | 7篇 |
排序方式: 共有891条查询结果,搜索用时 31 毫秒
1.
E. v. c. 《European Journal of Forest Research》1868,12(1):303-303
Ohne Zusammenfassung 相似文献
2.
European Journal of Forest Research - 相似文献
3.
Lreiherr v. Sturmfeder 《European Journal of Forest Research》1863,7(1):430-431
Ohne Zusammenfassung 相似文献
4.
5.
6.
Regarding the estimation of the energy concentration or digestibility of herb-dominated forage and plant samples from winter pastures, it could be expected that the estimation is only reliable when in vitro methods with rumen fluid as inoculum (= gas production techniques) are used. For the verification of this thesis based on logical reflections, an in vitro-method with rumen fluid added as inoculum, as well as chemical, and enzymatic methods were applied under consideration of existing estimating functions. As a possible reason for the observed divergence of the methods, effects of fungal infections or, respectively, secondary compounds in herbs are discussed. At the present state of knowledge, it is adequate to estimate the energy concentration in vitro by gas tests, as far as fattening types like suckler cows and beef cattle are concerned, maybe in contrast to the forage evaluation for dairy cows. 相似文献
7.
v. Fürst 《Forstwissenschaftliches Centralblatt》1911,33(2):100-108
Ohne Zusammenfassung 相似文献
8.
Nicolas Rose Alain Abhervé-Guéguen Gérald Le Diguerher Eric Eveno Jean-Pierre Jolly Philippe Blanchard Aurélie Oger André Jestin François Madec 《Livestock Production Science》2005,95(3):177-186
The aim of this study was to determine the potential risk factors for PMWS at the individual pig level and assess the effect of the Pietrain paternal genetic background of the animals in a cohort study. The survey was set up in four PMWS-affected farms with 2 repetitions (batches) per farm. A representative sample of 60 pigs per batch, stratified according to the paternal genetic background (Pietrain: yes vs. no), was randomly selected after farrowing. The representative cohort was divided into 8 batches and the pigs were individually monitored from birth to slaughter. Survival analysis was used to determine the factors related to the time to PMWS. The litter-cluster effect was taken into account using the marginal Cox model (robust estimation of the covariance matrix) and the gamma shared frailty model which were compared.No protective effect of the Pietrain breed on the time to PMWS and the proportion of affected pigs in the offspring was found in this study. Piglets showing low circovirus type 2 (PCV2) titres at 7 weeks-old with no subsequent seroconversion and piglets from PCV2 negative sows were most likely to be affected by PMWS (HR=7.0 and 2.8, respectively). Active infection of the pregnant dams with parvovirus was related to an increased risk of PMWS in the offspring (HR=2.3). Neck injuries due to poorly performed injections in the dams were associated with an increased risk of PMWS with the marginal model (HR=2.1). Oxytocin injection (dams) during farrowing was protective against PMWS in the offspring (HR=0.6). 相似文献
9.
Bérénice Agnola Stéphane Boury Claudie Monot Anne Quillévéré Yves Hervé Drissa Silué 《European journal of plant pathology / European Foundation for Plant Pathology》2003,109(5):471-478
A rapid resistance/susceptibility test for Peronospora parasitica (downy mildew) was established by inoculating leaf-disks of four Brassica oleracea accessions. Several conditions were tested: disk disinfection or not, agar medium with or without nutrients and with 50 or 100 ppm of benzimidazole. Using disinfected disks placed on agar (no nutrient and benzimidazole at 50 or 100 ppm), the responses of leaf-disks to four isolates were similar to those obtained using the classical cotyledon test, whereas undesired contaminations occurred in all other conditions. The possible effect of the particular leaf used for obtaining the disks was also studied. In each incompatible interaction tested, disks were resistant whatever the leaf used. In compatible interactions, susceptible phenotypes were observed on disks derived from the six lowest leaves, but disks from upper leaves were resistant. The genetic basis of resistance in a F1 hybrid broccoli was assessed, by testing six isolates on an F2 population derived from this hybrid. The cotyledon test only allows inoculation of two isolates per seedling, whereas many isolates can be tested on each plant by using leaf-disks. The segregation of the resistance to each of the six isolates was analysed: two dominant genes (tightly linked) control resistance to all isolates (one to five isolates; the other to only one isolate). 相似文献
10.
Martin M.T. Glie B. 《European journal of plant pathology / European Foundation for Plant Pathology》1997,103(5):427-431
Plum pox potyvirus (PPV) induces in infected Nicotiana clevelandii cells characteristic crystalline inclusions known as nuclear inclusions (NI) when located in the nucleus and as dense material (Dm) when located in the cytoplasm. Crystalline inclusions contain protease (NIa) and RNA-dependent RNA polymerase (NIb) proteins. It is now well established for all potyviruses that cylindrical inclusions contain CI helicase ATPase protein (Martin et al., 1992). The intracellular location of other non-structural PPV proteins remains unknown. Using Escherichia coli expression vectors, specific antibodies were obtained against P1, P3, 6K2 and NIb PPV proteins for which antibodies were not yet available. As expected, NIb antiserum labelled crystalline inclusions. P1, P3 and 6K2 proteins were present in both types of crystalline inclusions found in the nucleus and in the cytoplasm of PPV-infected leaves of N. clevelandii, suggesting that nuclear inclusions and dense material were composed of the same proteins. This composition is discussed. 相似文献