全文获取类型
收费全文 | 431篇 |
免费 | 11篇 |
国内免费 | 2篇 |
专业分类
林业 | 46篇 |
农学 | 9篇 |
基础科学 | 1篇 |
80篇 | |
综合类 | 16篇 |
农作物 | 16篇 |
水产渔业 | 84篇 |
畜牧兽医 | 175篇 |
园艺 | 3篇 |
植物保护 | 14篇 |
出版年
2023年 | 7篇 |
2022年 | 2篇 |
2021年 | 17篇 |
2020年 | 9篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 15篇 |
2015年 | 13篇 |
2014年 | 13篇 |
2013年 | 40篇 |
2012年 | 10篇 |
2011年 | 23篇 |
2010年 | 10篇 |
2009年 | 18篇 |
2008年 | 39篇 |
2007年 | 21篇 |
2006年 | 29篇 |
2005年 | 18篇 |
2004年 | 18篇 |
2003年 | 27篇 |
2002年 | 16篇 |
2001年 | 17篇 |
2000年 | 13篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 7篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1979年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1967年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有444条查询结果,搜索用时 281 毫秒
51.
Dey Daniel C. Knapp Benjamin O. Battaglia Mike A. Deal Robert L. Hart Justin L. O’Hara Kevin L. Schweitzer Callie J. Schuler Thomas M. 《New Forests》2019,50(1):11-40
New Forests - For millennia, natural disturbance regimes, including anthropogenic fire and hunting practices, have led to forest regeneration patterns that created a diversity of forest lands... 相似文献
52.
R.J. Yates J.G. Howieson W.G. Reeve L. Brau J. Speijers K. Nandasena D. Real E. Sezmis G.W. O’Hara 《Soil biology & biochemistry》2008,40(3):822-833
We have previously reported significant strain–host incompatibility between the microsymbiont Rhizobium leguminosarum biovar trifolii and Trifolium spp. related to geographic and phenological barriers. Additionally, we have shown that an effective symbiosis between strains of R. l. trifolii and clover was established despite the soil harbouring ineffective R. l. trifolii capable of nodulating the host. We termed this “selection” for effective symbiosis. This paper reports glasshouse-based experiments to validate and further explore this in situ selection phenomenon. The effect of cell density and strain ratio at the time of inoculation, as well as soil pH, were investigated on two hosts (Trifolium purpureum and Trifolium polymorphum) that were each exposed to one microsymbiont capable and one incapable of N2 fixation. In co-inoculation experiments at a cell density of 104 cells/mL, each host nodulated solely with its effective strain, even when this strain was outnumbered 100-fold by the ineffective strain. However, the selection process ceased when the effective strain was outnumbered 1000-fold. At higher basal cell concentrations of 105–108 cells/mL, selection for WSM1325 to form effective nodulation on T. purpureum was evident, but was significantly reduced as the ratio of ineffective cells in the inoculum increased above 4-fold. The results indicate that the selection mechanism is highly dependent on the basal rhizobial cell density. Soil pH did not significantly alter the process, and both strains grew at similar rates and formed nodules at similar rates. A preliminary investigation into the genetic backgrounds of WSM1325 and WSM2304 revealed that although their 16S rRNA sequences were identical, they have considerable differences in their symbiotic and chromosomal replicons through examination of atpD, GSII and nodD sequences. 相似文献
53.
Landscape Ecology - In March of 2011 a huge tsunami devastated forest habitats along the coast of Sendai Bay in northeastern Japan. Evaluation and monitoring of the changes in habitat connectivity... 相似文献
54.
Enhanced type X collagen expression in the extruded nucleus pulposus of the chondrodystrophoid dog 总被引:1,自引:0,他引:1
Itoh H Asou Y Hara Y Haro H Shinomiya K Tagawa M 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2008,70(1):37-42
The causes of early degeneration and calcification of the nucleus pulposus in the chondrodystrophoid dog are poorly understood, and the underlying molecular mechanism of this process has not yet been clearly defined. Type X collagen is one of the key molecules in endochondral bone growth and development, especially matrix calcification. The relationship between type X collagen and disc degeneration and calcification in chondrodystrophoid dogs has not yet been studied. We analyzed the expression of type X collagen in degeneration and calcification of the intervertebral disc in chondrodystrophoid dogs, using type X collagen immunohistochemistry. Control intervertebral discs were collected from five dogs (4 female, 1 male, average age 1.3 years, beagle breed). Degenerated intervertebral discs were surgically removed from 11 canine patients with intervertebral disc extrusion (1 female, 10 male, average age 5.1 years, dachshund breed) in Nippon Veterinary and Animal Science University. All extruded disc samples showed hypertrophic changes and clustering of cells, typical features observed in the degenerated nucleus pulposus. The relative expression of type X collagen in the degenerated nucleus pulposus (84.3 +/- 11.0%) was significantly increased compared to the control nucleus pulposus (5.4 +/- 5.4%). Our findings suggest that type X collagen might contribute to the development of degeneration or calcification in the nucleus pulposus of the chondrodystrophoid dog. 相似文献
55.
Nezu Y Nezu Y Shigihara K Harada Y Yogo T Hara Y Tagawa M 《American journal of veterinary research》2008,69(4):512-518
OBJECTIVE: To determine the effects of intestinal ischemia and reperfusion on the expression of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 mRNAs in the jejunum, liver, and lungs of dogs. ANIMALS: 8 healthy adult Beagles. PROCEDURES: In each dog, the cranial mesenteric artery was occluded for 0 (control group; n=4) or 60 (I-R group; 4) minutes, followed by reperfusion for 480 minutes; serum TNF-alpha and IL-6 activities and expression levels of TNF-alpha and IL-6 mRNAs in jejunal, hepatic, and lung tissues were measured before and at the end of the ischemic period and at intervals during reperfusion. For each variable, values were compared between the control and I-R groups at each time point. RESULTS: Compared with the control group, serum IL-6 activity increased significantly after 180 minutes of reperfusion in the I-R group; also, jejunal TNF-alpha mRNA expression increased significantly after 60 (peak) and 180 minutes of reperfusion. In the I-R group, expressions of IL-6 mRNA in the liver and TNF-alpha and IL-6 mRNAs in the lungs increased significantly at 480 minutes of reperfusion, compared with the control group. Serum TNF-alpha activity, expression of IL-6 mRNA in the jejunum, and expression of TNF-alpha mRNA in the liver in the control and I-R groups did not differ. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that the liver, lungs, and jejunum contributed to the production of TNF-alpha and IL-6 after intestinal ischemia and reperfusion in dogs, suggesting that intestinal ischemia and reperfusion induce a systemic proinflammatory cytokine response in dogs. 相似文献
56.
Commercially available vaccines have been used widely to prevent feline calicivirus infection (FCI). However, with their widespread
use, field strains, which are weakly cross-reactive with the live-virus vaccine strain F9, have posed the problem of vaccine
breakdown. Recently the existence of FCV—associated virulent systemic disease (VSD) has been published. But their molecular
diversity, antigenic mutations and physicochemical property have not been sufficiently clarified. Thus, we experimentally
gave the vaccine breakdown strain (VBS) H10 to cats that had been inoculated with an F9 live vaccine. After the administration
of strain H10, vaccinated cats (1 through 4) had no respiratory symptoms, whereas the non-vaccinated cat 5 showed clinical
symptoms such as a fever of over 40°C, loss of vitality, decreased appetite, diarrhea, and nasal discharge after receiving
strain H10, and died. Lethal FCV is rare, and may be a virulent systemic disease (VSD)—inducing strain. This is the initial
report on VSD in Japan. It has been reported that symptoms of VSD were similar in vaccinated and nonvaccinated cats on experimental
infection. However, no VSD-like symptoms developed, and the incidence of the disease varied depending on the presence or absence
of vaccination, suggesting that there are two mechanisms of vaccine breakdown: one is associated with the vaccine immunity
level, and the other is not. The characteristics of the VBS revealed were: (1) the duration of virus excretion was short when
the originally carried antibody titer before virus challenge was high, (2) the excreted viral molecular species varied daily,
not being limited to a specific species with time, and (3) the acquired physicochemical properties did not persist, and altered
daily. FCV-VBS alters the molecular species and physicochemical properties daily due to the reduction of host immunity, which
may lead to VSD. 相似文献
57.
Hideki Endo Masataka Yoshida Truong Son Nguyen Yuki Akiba Masahiro Takeda Kohei Kudo 《Anatomia, histologia, embryologia》2019,48(1):3-11
Semiaquatic walking has resulted in the evolution of functional and morphological changes in various hoofed mammals, such as hippopotamus and Brazilian tapir. The biomechanics of skilful walking in wetlands or at the bottom of a waterbody involve the medio‐lateral opening and closing of the feet to effectively support and stabilize the body on soft ground and to reduce the water resistance during recovery stroke, respectively. We demonstrate that the opening and closing of the feet in hippopotamus and Brazilian tapir are mediated by the adduction and abduction of the most medial and lateral phalanges from the CT examination. The axial toes, metacarpals and metatarsals do not contribute to changes in the width and shape of the feet, unlike the medial and lateral toes. We suggest that this semiaquatic walking motion is derived from the original terrestrial mode of locomotion, in contrast to the highly functional swimming motion using webs or fins in morphologically modified feet and tail. From the present data we demonstrate that semiaquatic locomotion evolved due to the acquisition of adductor–abductor mobility in the phalanges of the most medial and lateral digits, as shown in hippopotamus and Brazilian tapir. 相似文献
58.
Y Kuroda M Yoshida T Shibahara T Matsui T Nakane H Hara Y Inoshima H Sentsui 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1999,61(7):749-753
A disease characterized by papules, nodules, vesicles and, rarely, pustules and ulcers on teats was seen among cattle on a farm in Chiba Prefecture, Japan. A virus was isolated by inoculation of fetal bovine lung cell cultures from a vesicle on a teat of an infected cow. The virus was subsequently passaged in fetal bovine lung and muscle cells in which it produced complete cytopathic changes. The virus was identified by physicochemical examinations and electromicroscopic observation as a parapoxvirus. A seroepidemiological survey was performed on antibody to the isolated virus by the agar gel immunodiffusion test. The isolated virus formed a precipitation line which cross reacted with other parapoxviruses isolated previously in Japan. The positive rate was more than 50% among cattle in the Kanto district. The positive rate increased with age. It was suggested that parapoxvirus infection might have already been prevalent among cattle in Japan. 相似文献
59.
To standardize conditions during the final maturation and ovulation of ovarian follicles from Japanese eel, we have developed
a culture system for the production of fertilizable eggs from post-vitellogenic ovarian follicles in vitro. Post-vitellogenic
ovarian follicles were incubated in culture medium supplemented with 17α,20β-dihydroxy-4-pregnen-3-one (DHP) with or without
bovine serum albumin (BSA) to assess the effects of protein concentration. Eggs that ovulated during incubation were fertilized,
and the remaining follicles were incubated in prostaglandin F2α (PGF2α) for a further 3 or 6 h before fertilization. Male eels were injected repeatedly with human chorionic gonadotropin. The quality
of eggs obtained under the different culture conditions was evaluated after artificial fertilization in terms of hatching
success. Hatching rates tended to decrease with increasing concentrations of BSA in the incubation medium in a dose-dependent
manner. The addition of PGF2α drastically increased the number of eggs that ovulated, but the rate of hatching was greatly decreased compared with eggs
obtained earlier by DHP incubation alone. The larvae obtained from artificially fertilized eggs produced in vitro survived
for 14 days without feeding. We conclude that in vitro culture systems thus have a great potential for the acquisition of
good quality eggs under tightly controlled artificial conditions, culminating in the production of eel larvae. 相似文献
60.
Saitoh Kanae Yoshimura Tomohiro Sun Luchuanyang Yang Min Wang Yao Taniyama Shigeto Hara Kenji Murayama Fumihito Nikawa Takeshi Tachibana Katsuyasu Hirasaka Katsuya 《Fisheries Science》2020,86(1):187-196
Fisheries Science - Fish oil containing omega-3 polyunsaturated fatty acids (PUFA) attenuates chronic inflammation found in obesity, leading to a reduction in insulin resistance. The effect of fish... 相似文献