全文获取类型
收费全文 | 39205篇 |
免费 | 1984篇 |
国内免费 | 4364篇 |
专业分类
林业 | 4352篇 |
农学 | 5838篇 |
基础科学 | 3653篇 |
6429篇 | |
综合类 | 12411篇 |
农作物 | 2213篇 |
水产渔业 | 1443篇 |
畜牧兽医 | 5327篇 |
园艺 | 1401篇 |
植物保护 | 2486篇 |
出版年
2024年 | 178篇 |
2023年 | 551篇 |
2022年 | 1426篇 |
2021年 | 1828篇 |
2020年 | 1707篇 |
2019年 | 1597篇 |
2018年 | 1172篇 |
2017年 | 1621篇 |
2016年 | 1458篇 |
2015年 | 1950篇 |
2014年 | 1826篇 |
2013年 | 2202篇 |
2012年 | 2710篇 |
2011年 | 2837篇 |
2010年 | 2593篇 |
2009年 | 2381篇 |
2008年 | 2158篇 |
2007年 | 2057篇 |
2006年 | 1942篇 |
2005年 | 1753篇 |
2004年 | 807篇 |
2003年 | 704篇 |
2002年 | 563篇 |
2001年 | 598篇 |
2000年 | 672篇 |
1999年 | 836篇 |
1998年 | 769篇 |
1997年 | 659篇 |
1996年 | 594篇 |
1995年 | 634篇 |
1994年 | 502篇 |
1993年 | 433篇 |
1992年 | 454篇 |
1991年 | 340篇 |
1990年 | 300篇 |
1989年 | 203篇 |
1988年 | 164篇 |
1987年 | 125篇 |
1986年 | 63篇 |
1985年 | 34篇 |
1984年 | 31篇 |
1983年 | 17篇 |
1982年 | 26篇 |
1981年 | 20篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1977年 | 4篇 |
1966年 | 4篇 |
1964年 | 5篇 |
1956年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Nan‐Xi Hu Mei Chen Yi‐Song Liu Qi Shi Bo Yang Huan‐Cheng Zhang Pi Cheng Qi Tang Zhao‐Ying Liu Jian‐Guo Zeng 《Journal of veterinary pharmacology and therapeutics》2019,42(2):197-206
Sanguinarine (SA) and chelerythrine (CHE) are the main active components of the phytogenic livestock feed additive, Sangrovit®. However, little information is available on the pharmacokinetics of Sangrovit® in poultry. The goal of this work was to study the pharmacokinetics of SA, CHE, and their metabolites, dihydrosanguinarine (DHSA) and dihydrochelerythrine (DHCHE), in 10 healthy female broiler chickens following oral (p.o.) administration of Sangrovit® and intravenous (i.v.) administration of a mixture of SA and CHE. The plasma samples were processed using two different simple protein precipitation methods because the parent drugs and metabolites are stable under different pH conditions. The absorption and metabolism of SA following p.o. administration were fast, with half‐life (t1/2) values of 1.05 ± 0.18 hr and 0.83 ± 0.10 hr for SA and DHSA, respectively. The maximum concentration (Cmax) of DHSA (2.49 ± 1.4 μg/L) was higher that of SA (1.89 ± 0.8 μg/L). The area under the concentration vs. time curve (AUC) values for SA and DHSA were 9.92 ± 5.4 and 6.08 ± 3.49 ng/ml hr, respectively. Following i.v. administration, the clearance (CL) of SA was 6.79 ± 0.63 (L·h?1·kg?1) with a t1/2 of 0.34 ± 0.13 hr. The AUC values for DHSA and DHCHE were 7.48 ± 1.05 and 0.52 ± 0.09 (ng/ml hr), respectively. These data suggested that Sangrovit® had low absorption and bioavailability in broiler chickens. The work reported here provides useful information on the pharmacokinetic behavior of Sangrovit® after p.o. and i.v. administration in broiler chickens, which is important for the evaluation of its use in poultry. 相似文献
102.
Yang Wang Chao Wang Zhuocheng Hou Kai Miao Haichao Zhao Rui Wang Min Guo Zhonghong Wu Jianhui Tian Lei An 《畜牧与生物技术杂志(英文版)》2014,(1):53-63
The endometrium of sheep consists of plenty of raised intercaruncular areas (IC). In order to better understand aglandular areas called caruncular (C), and intensely glandular the endometrium involved mechanisms of implantation, we used LC-MS/MS technique to profile the proteome of ovine endometrial C areas and IC areas separately during the peri-implantation period, and then compared the proteomic profiles between these two areas. We successfully detected 1740 and 1813 proteins in C areas and IC areas respectively. By comparing the proteome of these two areas, we found 170 differentially expressed proteins (DEPs) (P 〈 0.05), functional bioinformatics analysis showed these DEPs were mainly involved in growth and remodeling of endometrial tissue, cell adhesion and protein transport, and so on Our study, for the first time, provided a proteomic reference for elucidating the differences between C and IC areas, as an integrated function unit respectively, during the peri-implantation period. The results could help us to better understand the implantation in the ewes. In addition, we established a relatively detailed protein database of ovine endometrium, which provide a unique reference for further studies. 相似文献
103.
Shelan Liu Yong Yang Zhifeng Pang Ying Liu Huan Li Jian Cai Zhuoying Wu Yan Luo Yuhuan Tang Lihong Ying Shuwen Qin Ziping Miao Na Zhao Yijuan Chen Jinren Pan Shijian Li Zhao Yu Feng Ling Enfu Chen Zhiping Chen 《Zoonoses and public health》2023,70(1):93-102
A cluster of Chlamydia psittaci (C. psittaci) cases was reported in Zhejiang Province, China, 2019. This study evaluates the extent of the outbreak and determines the source of infection. Real-time PCR and sequencing of the ompA gene of C. psittaci were performed to identify the cases, the domesticated poultry and close contacts. The index patient was a 76-year-old woman with chronic vertigo, and Case 2 was a 64-year-old female farmer with herpes zoster. Both women bought psittaci-infected chickens or ducks from the same mobile street vendor and raised them for 10 days and 23 days before fever onset. There were no direct contact between the two women. C. psittaci test was positive for the two patients, one sick chicken, three healthy ducks and the vendor's chicken cage. Phylogenetic analysis showed that all seven C. psittaci positive samples carried identical ompA genotype A of C. psittaci. Of all of the patients' 148 close contacts, none tested positive for C. psittaci, or developed acute respiratory symptoms. Both patients were discharged after a 4-week hospital stay. In conclusion, the source of this cluster was the poultry infected with C. psittaci, which occasionally cause infections in farmers, but inter-human transmission seems unlikely. 相似文献
104.
Juzuo Zhang Liqun Xue Ang Nie Qing Yang Xuan Peng Zhilong Chen Lisha Yang Yang Xie Anwen Yuan Junfei Xu 《Reproduction in domestic animals》2020,55(11):1479-1489
Non-infectious prenatal mortality severely affects the porcine industry, with pathological placentation as a likely key reason. Previous studies have demonstrated that peroxisome proliferator-activated receptor gamma (PPARγ) deficiency causes defects in the uteroplacental vasculature and induces embryonic losses in mice. However, its role in porcine placental angiogenesis remains unclear. In the present study, PPARγ expression was investigated in porcine uteroplacental tissues at gestational day (GD) 25, GD40 and GD70 via quantitative polymerase chain reaction (qPCR), Western blot and immunohistochemistry (IHC). Moreover, the roles of PPARγ in porcine placental angiogenesis were investigated using a cell model of porcine umbilical vein endothelial cells (PUVECs) to conduct proliferation, migration and tube formation assays in vitro and a mouse xenograft model to assess capillary formation in vivo. The results showed that PPARγ was mainly located in the glandular epithelium, trophoblast, amniotic chorion epithelium and vascular endothelium, as indicated by the higher expression levels at GD25 and GD40 than at GD70 in endometrium and by higher expression levels at GD40 and GD70 than at GD25 in placenta. Moreover, PPARγ expression was significantly downregulated in placenta with dead foetus. In PUVECs, knocking out PPARγ significantly inhibited proliferation, migration and tube formation in vitro and inhibited capillary formation in mouse xenografts in vivo by blocking S-phase, promoting apoptosis and downregulating the angiogenic factors of VEGF and its receptors. Overall, the spatiotemporal heterogeneity of PPARγ expression in porcine uteroplacental tissue suggests its vital role in endometrial remodelling and placental angiogenesis, and PPARγ regulates placental angiogenesis through VEGF-mediated signalling. 相似文献
105.
Young-Don Son Da-Jung Kim Ji-Houn Kang Dong-Woo Chang Young-Bae Jin Dong-In Jung Chulhyun Lee Mhan-Pyo Yang Sang-Rae Lee Byeong-Teck Kang 《Irish veterinary journal》2015,68(1)
A 16-year-old, castrated, male English cocker spaniel dog was presented due to generalized alopecia. Routine clinical pathology, endocrine and abdominal ultrasonography results were consistent with a diagnosis of pituitary-dependent hyperadrenocorticism. The adenohypophyseal lesion was clearly visualized on both 3 T and 7 T magnetic resonance imaging (MRI) of the pituitary gland. Although biochemical and MRI findings were consistent with a functional pituitary microtumor, a pituitary lesion was not detected using 18F-fluorodeoxyglucose positron emission tomography (FDG-PET). This report firstly describes the application of high-resolution FDG-PET to a spontaneous pituitary microtumor in a dog. 相似文献
106.
Ah Young Kim Hye-Sun Kim Ji-Houn Kang Mhan-Pyo Yang 《Journal of veterinary science (Suw?n-si, Korea)》2015,16(3):333-340
This study was conducted to determine whether serum adipokine concentrations differed between healthy dogs and dogs with diabetes mellitus (DM). To accomplish this, 19 dogs with newly diagnosed DM were compared to 20 otherwise healthy dogs. The serum concentrations of visfatin, leptin, IL-1β, IL-6, IL-18, and TNF-α were significantly higher in diabetic dogs than in healthy dogs, whereas the serum adiponectin concentrations were lower in diabetic dogs. However, there were no significant differences in the IL-10 and resistin levels between groups. The serum leptin concentrations in diabetic dogs with and without concurrent disorders differed significantly. Treatment with insulin induced a significant decrease in IL-6 in diabetic dogs without concurrent disorders. These results show that the clinical diabetic state of dogs could modulate the circulating visfatin and adiponectin concentrations directly, while upregulation of leptin was probably a result of concurrent disorders rather than an effect of persistent hyperglycemia as a result of DM. 相似文献
107.
108.
109.
不同遮荫强度对草地早熟禾草坪质量的影响 总被引:1,自引:0,他引:1
为研究不同遮荫强度对新建草地早熟禾(Poa pratensis)草坪生长状况的影响,于2009年5月1日-11月6日进行试验,共设计自然光照、轻度遮荫、中度遮荫和重度遮荫4种不同遮荫强度,对干旱胁迫下草地早熟禾的生长速率、草坪质量、草屑重量、叶色值、电导率和地下生物量等形态指标和生理指标进行观察测定。结果表明,在少雨时节中度遮荫的草坪质量较高,多雨时节则轻度遮荫的草坪质量较好;适度遮荫下草坪草的生长正常,叶色较好,电导率较小,草坪质量较高。因此,可以利用适度遮荫,减少夏季高温与干旱对草地早熟禾草坪的伤害,改善草坪质量。 相似文献
110.