全文获取类型
收费全文 | 27012篇 |
免费 | 1618篇 |
国内免费 | 2533篇 |
专业分类
林业 | 2042篇 |
农学 | 1931篇 |
基础科学 | 1270篇 |
2862篇 | |
综合类 | 12612篇 |
农作物 | 1863篇 |
水产渔业 | 1303篇 |
畜牧兽医 | 4302篇 |
园艺 | 1731篇 |
植物保护 | 1247篇 |
出版年
2024年 | 115篇 |
2023年 | 443篇 |
2022年 | 981篇 |
2021年 | 1141篇 |
2020年 | 1007篇 |
2019年 | 1034篇 |
2018年 | 743篇 |
2017年 | 1169篇 |
2016年 | 866篇 |
2015年 | 1229篇 |
2014年 | 1224篇 |
2013年 | 1475篇 |
2012年 | 2250篇 |
2011年 | 2268篇 |
2010年 | 2239篇 |
2009年 | 1956篇 |
2008年 | 2032篇 |
2007年 | 1991篇 |
2006年 | 1611篇 |
2005年 | 1348篇 |
2004年 | 836篇 |
2003年 | 502篇 |
2002年 | 609篇 |
2001年 | 522篇 |
2000年 | 491篇 |
1999年 | 260篇 |
1998年 | 133篇 |
1997年 | 106篇 |
1996年 | 91篇 |
1995年 | 79篇 |
1994年 | 72篇 |
1993年 | 78篇 |
1992年 | 71篇 |
1991年 | 44篇 |
1990年 | 41篇 |
1989年 | 27篇 |
1988年 | 17篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 2篇 |
1981年 | 4篇 |
1965年 | 2篇 |
1963年 | 4篇 |
1962年 | 6篇 |
1957年 | 2篇 |
1956年 | 9篇 |
1955年 | 7篇 |
1954年 | 2篇 |
1953年 | 2篇 |
1947年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
番石榴果实发育的初步研究 总被引:7,自引:0,他引:7
以东山月拔和二十一世纪这2个品种为试材,研究了番石榴(Psidium guajava L)果实的发育动态规律。结果表明:番石榴的果实发育呈现双“S”型;果实重量和果核重量的发育呈显著的正相关;推测果实发育后期为进行果实产期调控的关键时期;建议以果实发育的直径大小以及果实转蒂下垂作为确定进行产期调控的田间依据。 相似文献
75.
6-BA在葡萄植株体内的运转和分配 总被引:10,自引:0,他引:10
以葡萄为试材,研究了葡萄根、茎、叶、果等器官对6-苄基腺嘌呤(6-BA)的吸收及它在植株内的运转和分配。结果表明,对1年生葡萄幼苗茎部引入或叶片涂抹6-BA,1h后,在植株所有部位都有分布,其中以茎尖和根部浓度较高,表现为快速、非极性的运输特性。茎部引入5d之内,植株根内6-BA呈持续升高趋势,茎尖内6-BA虽然有波动,但是最后仍达到最大;而叶片涂抹则在涂抹后5h时,全株各部位6-BA浓度达到最大,5d后,除引入叶片外,其它部位几乎测不到6-BA。盛花后30d,果穗浸蘸和穗轴引入6-BA,2h后,果皮、果肉、种子中6-BA浓度达到高峰,以后逐渐下降,果穗浸蘸30d后,果实各部位均已测不到6-BA,穗轴引入30d后,果皮和果肉内仍能测到6-BA,但种子内已测不到。 相似文献
76.
77.
ZHENG Hui LI Hong-yi WANG Zi-neng ZHAO Ying-she YU Li HE Si-cun BAI Zhi-quan ZHOU Zuo-yan YAO Ping WANG Yue-chun 《园艺学报》2002,18(5):553-555
AIM: The purpose of the present study was to explore the relationship between interleukin-6 mRNA expression and endometriosis. METHODS: Using the rat model, IL-6 mRNA expression in the endometrium was examined by RT-PCR. RESULTS: The expression of IL-6 mRNA in control rats did not change at 2, 4, 6 and 8 weeks after sham operation (P>0.05), but in model rats it gradually increased at 2, 4, 6 and 8 weeks after endometriosis (P<0.01). The expression of IL-6 mRNA in uterine endometrium with endometriosis was lower than in endometriotic tissue, but higher than in endometrium from healthy controls. CONCLUSION: The IL-6 mRNA expression may contribute to the development of endometriosis . The increase in IL-6 mRNA expression may promote the implantation and growth of endometriotic tissue. 相似文献
78.
CHENG Biao FU Xiao-bing SHENG Zhi-yong SUN Tong-zhu SUN Xiao-qing LI Jian-fu 《园艺学报》2002,18(11):1333-1336
AIM: To examine the expression of alpha-smooth muscle actin in scar tissue, and observe the phenomenon of apoptosis and its involvement in the process of pathological scarring and the presence of myofibroblasts or absence of cell in the dermis. To investigate the potential role of reparative cell apoptosis in hyperplastic scar formation. METHODS: The samples of scar were obtained from post-burn patients undergoing plastic operation in our burn unit recently, and the samples of control came from skin donor site of the same patient correspondingly. TUNEL assays were performed to evaluate the number of apoptotic cells in scar versus normal skin. In situ hybridization and immunohistochemistry staining technique were employed to determine the expression of different dermis cells markers in scar tissue and normal skin. RESULTS: There existed evident difference in apoptotic cells in the dermis between scars tissue and normal human skin. The expression positive cells were much more in hyperplastic scars than that in normal human skin; the apoptotic cells of proliferative stage were slight more than that of mature stage. However, in proliferative stage, the number of apoptotic cells was higher for the combination of hyperplastic scar than normally healed flat scars. But in mature stage, no obviously difference was detected between hyperplastic scar and normally healed flat scar. The monoclonal anti-α smooth muscle actin (ASMA) expression was significantly stronger in proliferative stage than that of mature stage. CONCLUSIONS: With reconstitution of dermal tissue, myofibroblasts containing alpha-SM actin disappear under normal wound healing, probably as a result of apoptosis. The myofibroblast play a critical role in wound closure and in the pathologic sequelae of healing. 相似文献
79.
LIN Jun SUN Jie ZHOU Yan HUANG Xing XIONG Ping WANG Ya-ping DENG Chang-sheng 《园艺学报》2002,18(9):1112-114
AIM: To probe into the genetic susceptibility of HLA-DRB1 alleles to esophageal neoplasm in Hubei Han Chinese. METHODS: HLA-DRB1 gene polymorphism in 42 patients with esophageal neoplasm and 136 normal control subjects was studied by PCR and sequence. RESULTS: Allele frequency of HLA-DRB1 *0901 allele was significantly higher in esophageal cancer patients than those in normal controls(0.2500 vs 0.1397, P =0.028; the odds ratiO2.053; etiologic fraction 0.1282).There were no association between the rested HLA-DRB1 alleles with patients. CONCLUSION: Individuals carrying HLA-DRB1 *0901 may be susceptible to esophagealo carcinoma, its nucleotide sepuence approachs to the corresponded allele sequence(exoN2)published in GenBank. 相似文献
80.