全文获取类型
收费全文 | 1025篇 |
免费 | 53篇 |
专业分类
林业 | 29篇 |
农学 | 44篇 |
基础科学 | 3篇 |
100篇 | |
综合类 | 261篇 |
农作物 | 124篇 |
水产渔业 | 87篇 |
畜牧兽医 | 377篇 |
园艺 | 11篇 |
植物保护 | 42篇 |
出版年
2023年 | 3篇 |
2022年 | 15篇 |
2021年 | 30篇 |
2020年 | 8篇 |
2019年 | 14篇 |
2018年 | 20篇 |
2017年 | 13篇 |
2016年 | 24篇 |
2015年 | 17篇 |
2014年 | 26篇 |
2013年 | 47篇 |
2012年 | 68篇 |
2011年 | 72篇 |
2010年 | 40篇 |
2009年 | 40篇 |
2008年 | 83篇 |
2007年 | 85篇 |
2006年 | 85篇 |
2005年 | 70篇 |
2004年 | 49篇 |
2003年 | 46篇 |
2002年 | 49篇 |
2001年 | 38篇 |
2000年 | 26篇 |
1999年 | 13篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1980年 | 3篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1971年 | 2篇 |
1970年 | 3篇 |
1969年 | 2篇 |
排序方式: 共有1078条查询结果,搜索用时 10 毫秒
21.
Molecular cloning and expression analysis of pig CD81 总被引:1,自引:0,他引:1
Cho KW Kim SJ Park CG Park J Cho JY Kang HS Chun T 《Veterinary immunology and immunopathology》2007,120(3-4):254-259
CD81, also known as TAPA-1 (target of antiproliferative antibody 1), is a member of the tetraspanin family of proteins and a component of the B cell co-receptor complex. Several studies have shown that CD81 plays significant roles in a variety of immune responses, including activation of B cells and T cells. In this study, we cloned pig Cd81 cDNA using RT-PCR coupled with rapid amplification of cDNA ends (RACE)-PCR and determined the complete cDNA sequence of pig Cd81. Pig Cd81 cDNA contains an open reading frame (711 bp) encoding 236 amino acids. The identity of pig CD81 with those of human, cattle, rat, and mouse are 90.30%, 92.26%, 86.22%, and 86.22%, respectively. Alignment of the CD81 amino acid sequence with those of mammalian species showed that the large extracellular loop (LEL) is the most divergent, whereas other domains are largely conserved. Pig Cd81 mRNA was detected by RT-PCR in a broad range of tissues, including lymphoid tissues as well as nonlymphoid tissues, indicated variety of cellular functions of CD81 in most pig tissues. Flow cytometry analyses demonstrated that human CD81 antibody recognizes a pig CD81 on the cell surface. Further, immunohistochemistry analysis using human CD81 antibody on pig spleen was revealed that CD81 expression is widely diffused in spleen tissue. Future study will be focused on defining the functional role of CD81 during the course of pig infectious diseases. 相似文献
22.
Jung-Sun Baek Ei Ei Cho Deog-Bae Lee Nam-Jin Chung 《Journal of Crop Science and Biotechnology》2018,21(2):155-163
This study was carried out to develop an evaluation method to predict rice seedling establishment (SE) under low-temperature conditions. Two Korean-bred japonica cultivars, Shindongjin and Hopum were used in the experiment. Fresh seeds were treated with an accelerated aging (AA) at 40°C and 100% RH for 1-15 days. The SEs of the fresh and AA seeds were evaluated in nursery beds at 17°C, and their correlation coefficients with seed vigor values measured by 9 test methods including standard germination test (SGT), cool germination test (CLT), cold germination test (CDT), seedling growth rate test (SGRT), ascorbate peroxidase (APX), peroxidase (POX), superoxide dismutase (SOD), catalase (CAT), and α ‐amylase (AMY) activities. The percentage of SE decreased slowly from 75 to 0% with an increasing of AA period from 0 to 15 days. The result of nine vigor tests showed different correlations with the SE. SGT, CLT, SGRT, and POX were significantly correlated with the SE. In the correlation analysis with only short-term aging seeds (1-7 days), the SE was very highly correlated with SGT, CLT, CDT, SGRT, POX, and CAT. These results suggest that seed vigor values measured by several methods including SGT and POX could be used as a reference value to secure SE at low temperatures in nursery bed rice seedling culture. 相似文献
23.
A series of shape memory polyurethane (PU) copolymers synthesized from 1,4-phenyldiisocyanate (PDI), poly(tetramethyleneglycol)
(PTMG), 1,4-butanediol (BD) as a chain extender, and glycerol as a cross-linking agent were tested for the mechanical properties
and the shape memory effect at the temperature 20 °C above melting temperature (T
m), and were compared with other PUs synthesized from 4,4′-methylene-bis-phenyldiisocyanate (MDI), PTMG, and BD. Mechanical
properties and shape memory effect were improved substantially by adopting both PDI and glycerol. Interestingly, enthalpy
of melting and T
m were not affected by the glycerol content. Vibration and shock absorption ability was investigated by measuring both loss
tan δ and storage modulus with dynamic mechanical analyzer (DMA). 相似文献
24.
Khan MN Cho JY Lee MC Kang JY Park NG Fujii H Hong YK 《Journal of agricultural and food chemistry》2007,55(17):6984-6988
Two anti-inflammatory omega-3 polyunsaturated fatty acids (PUFAs) of stearidonic acid (SA) and eicosapentaenoic acid (EPA) and one pro-inflammatory omega-6 PUFA of arachidonic acid (AA) were isolated from the edible brown seaweed Undaria pinnatifida. SA was active against mouse ear inflammation induced by phorbol myristate acetate, with IC50 values of 160, 314, and 235 microg per ear for edema, erythema, and blood flow, respectively. EPA was also active against edema, erythema, and blood flow, with IC50 values of 230, 462, and 236 microg per ear, respectively. Although AA at low concentrations showed anti-inflammatory activities when measured 10 h later, AA doses of more than 243 microg per ear induced inflammatory symptoms 1 h later. Mature thalli generally had larger amounts of PUFAs than young thalli. The algal blade contained more omega-3 PUFAs than were found in other parts, while the holdfast contained extremely high amounts of AA. Late-season thalli showed increased amounts of PUFAs, especially AA. 相似文献
25.
Radial Immunodiffusion of Chicken Serum Proteins I. Standardization of Optimal Test Procedures 下载免费PDF全文
Optimal conditions were determined for the quantitaion of chicken serum albumin, conalbumin, IgG and IgM by the radial immunodiffusion test. The best diluent was 0.15 M phosphate buffered saline, pH 7.2. The optimal concentration of the rabbit antiserum in the agar plate was inversely related to the molecular weight of the protein under study. The incubation time required for maximum ring formation was directly related to the molecular weight of the proteins under study. The reproducibility of the tests was evaluated using stored and fresh antiserum-agar plates. 相似文献
26.
Flow cytometric assessment of ethylene glycol monoethyl ether on spermatogenesis in rats 总被引:1,自引:0,他引:1
Yoon CY Hong CM Cho YY Chung YH Min HK Yun YW Lee BJ Yang KH Lee YS Kim CK 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2003,65(2):207-212
The effects of ethylene glycol monoethyl ether (EGEE) on testicular cell populations in rats were investigated by a flow cytometric method. Rats were administered by gavage with EGEE at the various doses of 0 (saline alone), 100, 200, 400, and 800 mg/kg body weight/day for 4 weeks. The treatment of EGEE caused decreases in the weight of testis and epididymis and in the number of testicular cells. Histopathologically, exfoliation of germ cells into the tubular lumen was observed at the doses of above 200 mg/kg. The treatment of EGEE at the dose of 400 mg/kg caused moderate testicular degeneration. A significant depletion of haploid cells and a disproportionate ratio of diploid and tetraploid cells were observed as determined by flow cytometric analysis. These results indicate that the toxic effect of EGEE on the male reproductive system may be strongly associated with the disproportion of testicular germ cells. 相似文献
27.
Shin DH Lee KS Lee E Chang YP Kim JW Choi YS Kwon BS Lee HW Cho SS 《Anatomia, histologia, embryologia》2003,32(6):378-383
In this immunocytochemical study on the constitutive expression of Pax-7 protein in the postnatal chicken brain, Pax-7 showed region and cell type specific expression. In the optic tectum, only cells in grey matter showed positive immunoreactivities (IRs), whereas those in the white matters did not show any IRs. In thalamic nuclei and several pontine nuclei, we also localized Pax-7 positive IRs. On the contrary, in the cerebellum, Pax-7 was mainly localized within the Bergmann glia, whereas Purkinje cells did not show any IRs. In double immunolabelling studies, most of the Pax-7 IRs did not originate from neuroglial cells such as oligodendrocytes, microglia or astrocytes, but from neurons, with the exception of Bergmann glia in the cerebellum. The presence of Pax-7 IRs in the adult chicken brain could suggest that Pax-7 might play a role in maintaining normal physiological function in some postnatal chicken brain cells. 相似文献
28.
29.
Kim J Choi C Cho WS Chae C 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2000,62(7):771-773
Detection method of Lawsonia intracellularis was studied in formalin-fixed paraffin-embedded intestinal tissues from 5 naturally infected pigs by immunohistochemistry with a monoclonal antibody against outer membrane protein of L. intracellularis. Warthin-Starry silver stain revealed clusters of argyrophilic, slightly curved rod-shaped organisms in the apical cytoplasm of enterocytes. Immunohistochemical staining with a L. intracellularis-specific monoclonal antibody confirmed the presence of the organism in the apical cytoplasm of hyperplastic enterocytes. The presence of L. intracellularis in the ileum of pig with proliferative enteropathy was confirmed by polymerase chain reaction (PCR) further on the basis of amplification of 319 base pair products specific for porcine L. intracellularis chromosomal DNA. Immunohistochemistry and PCR may be a complementary method to confirm the diagnosis of L. intracellularis infection in pigs. 相似文献
30.
The present study was to construct a parentage testing system for Thoroughbred (TB) horse. A total number of 1,285 TB horse samples including 962 foals for parentage testing, 9 sires and 314 dams for individual identification were genotyped. Genomic DNA was extracted from 5 hair roots and genotyped by using 14 microsatellite markers (AHT4, AHT5, ASB2, ASB17, ASB23, CA425, HMS1, HMS3, HMS6, HMS7, HTG4, HTG10, LEX3 and VHL20). This method consisted of multiplexing PCR procedure and showed reasonable amplification of all PCR products. Genotypes were determined by genetic analyzer. The number of alleles per locus varied from 3 to 9 with a mean value of 6.36 in TB horse. The expected heterozygosity was ranged from 0.548 to 0.831 (mean 0.699), and the total exclusion probability of 14 microstellite loci was 0.9998. Of the 14 markers, ASB2, ASB17, ASB23, HMS7 and HTG10 loci have relatively high PIC value (> 0.7). Of the 962 foals, 960 foals were qualified by compatibility according to the Mendelism. These results suggest that the DNA typing method has high potential for parentage verification and individual identification of TB horses. 相似文献