全文获取类型
收费全文 | 865篇 |
免费 | 41篇 |
专业分类
林业 | 146篇 |
农学 | 64篇 |
基础科学 | 5篇 |
95篇 | |
综合类 | 116篇 |
农作物 | 16篇 |
水产渔业 | 34篇 |
畜牧兽医 | 388篇 |
园艺 | 15篇 |
植物保护 | 27篇 |
出版年
2021年 | 11篇 |
2020年 | 8篇 |
2019年 | 11篇 |
2018年 | 15篇 |
2017年 | 21篇 |
2016年 | 13篇 |
2015年 | 18篇 |
2014年 | 18篇 |
2013年 | 31篇 |
2012年 | 39篇 |
2011年 | 36篇 |
2010年 | 15篇 |
2009年 | 25篇 |
2008年 | 35篇 |
2007年 | 33篇 |
2006年 | 30篇 |
2005年 | 25篇 |
2004年 | 19篇 |
2003年 | 35篇 |
2002年 | 23篇 |
2001年 | 27篇 |
2000年 | 28篇 |
1999年 | 12篇 |
1998年 | 8篇 |
1997年 | 8篇 |
1996年 | 8篇 |
1994年 | 9篇 |
1992年 | 12篇 |
1991年 | 15篇 |
1990年 | 10篇 |
1989年 | 20篇 |
1988年 | 18篇 |
1987年 | 11篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 11篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 10篇 |
1977年 | 14篇 |
1975年 | 8篇 |
1974年 | 10篇 |
1973年 | 6篇 |
1972年 | 11篇 |
1971年 | 9篇 |
1969年 | 8篇 |
1967年 | 8篇 |
1966年 | 14篇 |
1924年 | 5篇 |
1921年 | 9篇 |
排序方式: 共有906条查询结果,搜索用时 15 毫秒
761.
D. P. Cherukuri S. K. Gupta A. Charpe S. Koul K. V. Prabhu R. B. Singh Q. M. R. Haq S. V. S. Chauhan W.E. Weber 《Plant Breeding》2003,122(3):204-208
The leaf rust resistance gene Lr19, transferred from Agropyron elongatum into wheat (Triticum aestivum L.) imparts resistance to all pathotypes of leaf rust (Puccinia recondita f.sp. tritici) in South‐east Asia. A segregating F2 population from a cross between the leaf rust resistant parent ‘HW 2046’ carrying Lr19 and a susceptible parent ‘Agra Local’ was screened in the phytotron against a virulent pathotype 77‐5 of leaf rust with the objective of identifying the molecular markers linked to Lr19. The gene was first tagged with a randomly amplified polymorphic DNA (RAPD) marker S73728. The RAPD marker linked to the gene Lr19 which mapped at 6.4 ± 0.035 cM distance, was converted to a sequence characterized amplified region (SCAR) marker. The SCAR marker (SCS73719) was specific to Lr19 and was not amplified in the near‐isogenic lines (NILs) carrying other equally effective alien genes Lr9, Lr28 and Lr32 enabling breeders to pyramid Lr19 with these genes. 相似文献
762.
Huijuan Li Jingjing Peng Karrie A. Weber Yongguan Zhu 《Journal of Soils and Sediments》2011,11(7):1234-1242
Purpose
Microbial ferric iron reduction is an important biogeochemical process in nonsulfidogenic anoxic environments, yet the structure of microbial communities involved is poorly understood because of the lack of a functional gene marker. Here, with ferrihydrite as the iron source, we characterized the potential Fe(III)-reducing bacteria from the paddy soil in the presence of different short-chain fatty acids, formate, acetate, propionate, pyruvate, succinate, and citrate. 相似文献763.
764.
Kamanga-Sollo E White ME Hathaway MR Weber WJ Dayton WR 《Domestic animal endocrinology》2011,40(1):60-66
Although androgenic and estrogenic steroids are widely used to enhance muscle growth and increase feed efficiency in feedlot cattle, their mechanism of action is not well understood. Although in vivo studies have indicated that androgens affect protein synthesis and protein degradation rate in muscle, results from in vitro studies have been inconsistent. We have examined the effects of trenbolone acetate (TBA), a synthetic androgen, on protein synthesis and degradation rates in fused bovine satellite cell (BSC) cultures. Additionally, we have examined the effects of compounds that interfere with binding of TBA or insulin-like growth factor-1 (IGF-1) to their respective receptors on TBA-induced alterations in protein synthesis and degradation rates in BSC cultures. Treatment of fused BSC cultures with TBA results in a concentration-dependent increase (P < 0.05) in protein synthesis rate and a decrease (P < 0.05) in degradation rate, establishing that TBA directly affects these parameters. Flutamide, a compound that prevents androgen binding to the androgen receptor, suppresses (P < 0.05) TBA-induced alterations in protein synthesis and degradation in fused BSC cultures, indicating the androgen receptor is involved. JB1, a competitive inhibitor of IGF-1 binding to the type 1 IGF receptor (IGF1R), suppresses (P < 0.05) TBA-induced alterations in protein synthesis and degradation, indicating that this receptor also is involved in the actions of TBA on both synthesis and degradation. In summary, our data show that TBA acts directly to alter both protein synthesis and degradation rates in fused BSC cultures via mechanisms involving both the androgen receptor and IGF1R. 相似文献
765.
Wimer CL Damiani A Osterrieder N Wagner B 《Veterinary immunology and immunopathology》2011,140(3-4):266-274
Equine herpesvirus type 1 (EHV-1) is highly prevalent in horses and causes rhinopneumonitis, abortion, and encephalopathy. Studies on the related human herpes simplex virus and of murine models of EHV-1 suggest that chemokines play important roles in coordinating of innate and adaptive immune responses, and thus effective control of herpesvirus infection and prevention of severe clinical disease. Here, equine peripheral blood mononuclear cells (PBMC) were infected with one of three EHV-1 strains, which differ in pathogenicity (RacL11, NY03=abortogenic, Ab4=neurogenic). Changes in CCL2, CCL3, CCL5, CXCL9 and CXCL10 chemokine gene expression relative to non-infected PBMC were measured by real-time PCR. CXCL9 and CXCL10 gene expression was up-regulated 10h post infection and decreased to the level of non-infected cells after 24h. CCL2 and CCL3 were significantly down-regulated 24h post infection with NY03 and Ab4. CCL5 was up-regulated 24h after infection with RacL11. Ab4 infected PBMC had significantly lower expression of all chemokines except CCL2 24h post infection then RacL11 infected cells. While there was not a significant difference between NY03 and the other strains, there was a trend with each chemokine toward NY03 inducing less expression then RacL11 but more then Ab4. The data suggested that EHV-1 infection of PBMC induced up-regulation of inflammatory chemokines CCL5, CXCL9 and CXCL10, and down-regulation of chemotactic CCL2 and CCL3. The data also implies that different EHV-1 strains have varying effects on all five chemokines, with the nuropathogenic strain, Ab4, having the greatest suppressive potential. 相似文献
766.
767.
Johanna Wolf Nicola Gerlach Karin Weber André Klima Gerhard Wess 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2013,42(2):196-206
Background
There is no agreement in current publications regarding the reliability of serum concentrations of natriuretic peptides (NPs) to detect dogs with subclinical myxomatous mitral valve disease (MMVD) and to differentiate between asymptomatic stages.Objectives
We sought to compare N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP) and pro‐atrial natriuretic peptide 31‐67 (proANP) concentrations between various stages of canine MMVD and to investigate the influence of age, weight, and sex.Methods
In this prospective study, dogs were classified in different disease stages using the modified Canine Heart failure International Expert Forum (CHIEF) system. Serum NP concentrations were compared between groups.Results
A total of 559 samples from 116 healthy dogs and 236 dogs with MMVD were analyzed. Using cut‐off values (1207 pmol/L for NT‐proBNP, 1578 fmol/mL for proANP), dogs with MMVD with and without congestive heart failure (CHF) could be differentiated with a sensitivity of 83% for both and specificities of 85% and 86%, respectively. Dogs staged in CHIEF B1 and B2 could not be distinguished based on NP concentrations due to wide variation within the groups. Intact females (means 598 pmol/L and 1036 fmol/mL, respectively) had significantly higher values of both NPs than intact males (315 pmol/L and 836 fmol/mL).Conclusions
NPs in canine MMVD are useful to discriminate between asymptomatic dogs and dogs with CHF. Due to a large overlap of NP‐concentrations between the groups, NPs do not seem to be useful to differentiate between dogs in stages B1 and B2. Interpretation of NT‐proBNP and proANP values should include consideration of sex‐specific differences. 相似文献768.
769.
770.
Scott P Terrell Deidre K Fontenot Michele A Miller Martha A Weber 《Journal of zoo and wildlife medicine》2003,34(4):380-384
An 11-yr-old female cheetah (Acinonyx jubatus) was diagnosed clinically with hepatic and renal disease and euthanatized after an extended illness. Postmortem examination revealed 8-10 L of milky white fluid in the abdominal cavity and markedly dilated lymphatic vessels within the intestinal mesentery. The abdominal fluid was a chylous effusion based on the cytologic predominance of lymphocytes and macrophages and comparison of cholesterol and triglyceride levels in the fluid and in serum. Gross and histopathologic lesions in the liver were consistent with a diagnosis of venoocclusive liver disease. Chylous ascites is uncommon with human chronic liver disease and is rarely identified in animals. 相似文献