全文获取类型
收费全文 | 4010篇 |
免费 | 224篇 |
国内免费 | 393篇 |
专业分类
林业 | 431篇 |
农学 | 456篇 |
基础科学 | 276篇 |
503篇 | |
综合类 | 1523篇 |
农作物 | 278篇 |
水产渔业 | 143篇 |
畜牧兽医 | 588篇 |
园艺 | 204篇 |
植物保护 | 225篇 |
出版年
2024年 | 23篇 |
2023年 | 48篇 |
2022年 | 177篇 |
2021年 | 193篇 |
2020年 | 185篇 |
2019年 | 179篇 |
2018年 | 113篇 |
2017年 | 215篇 |
2016年 | 130篇 |
2015年 | 160篇 |
2014年 | 198篇 |
2013年 | 243篇 |
2012年 | 294篇 |
2011年 | 302篇 |
2010年 | 295篇 |
2009年 | 253篇 |
2008年 | 258篇 |
2007年 | 229篇 |
2006年 | 192篇 |
2005年 | 160篇 |
2004年 | 117篇 |
2003年 | 69篇 |
2002年 | 69篇 |
2001年 | 70篇 |
2000年 | 57篇 |
1999年 | 67篇 |
1998年 | 49篇 |
1997年 | 40篇 |
1996年 | 41篇 |
1995年 | 37篇 |
1994年 | 20篇 |
1993年 | 34篇 |
1992年 | 21篇 |
1991年 | 24篇 |
1990年 | 18篇 |
1989年 | 19篇 |
1988年 | 2篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1962年 | 1篇 |
1956年 | 1篇 |
1948年 | 1篇 |
1943年 | 1篇 |
排序方式: 共有4627条查询结果,搜索用时 15 毫秒
91.
向日葵品种资源对菌核病抗性室内鉴定 总被引:1,自引:1,他引:0
利用两种不同的培养基培养核盘菌,用离体叶片接种方法对40个不同向日葵品种进行室内抗性鉴定,结果表明:在Minimal medium培养基上生长的核盘菌和PDA培养基相比,菌丝的生长速度大大降低。菌株经PDA培养基培养接种向日葵叶片后,不同向日葵品种之间抗性水平没有显著差异;而用Minimal medium培养基培养的菌株接种供试的向日葵不同品种叶片后,品种间表现出一定的抗性水平差异。依据接种后不同品种抗性水平的差异将供试向日葵品种划分为三组,即:抗病品种如食葵765、油葵KS7等,共3份;耐病品种如3146、新葵杂5号等,共9份;感病品种如LD1093、新葵杂6号等,共28份。 相似文献
92.
Pei-Chia Lan 《Asia Pacific viewpoint》2023,64(3):425-431
In this research note, I expand the discussion on multicultural policies in East Asia by proposing the concept of ‘geopolitical multiculturalism’. It describes that the receiving state promotes multiculturalism or pro-immigrant programmes and discourses to enhance the nation's global standing, regional importance, economic development, and geopolitical security. East Asian countries serve as illustrative examples of this concept, as their substantial immigrant populations are relatively recent, and the development of multicultural programmes is closely tied to international influence. I will first elaborate on three approaches to geopolitical multiculturalism, followed by a detailed analysis of Taiwan's case, including the recent implementation of the New Southbound Policy. I draw conclusions regarding the implications and potential applications of this concept for future research. 相似文献
93.
为建立饲料中替米考星含量的高效液相色谱检测分析方法,实验样品经水-乙腈-磷酸二丁胺溶液-四氢呋喃(805:115:25:55,V:V:V:V)提取后,振荡10 min,超声10 min,4000 r/min离心5 min,取上清液过0.45 μm有机微孔滤膜后供高效液相色谱仪分析测定。结果表明:替米考星在10 ~ 500 μg/mL质量浓度范围内线性关系良好,相关系数大于0.999,方法检出限为5 mg/kg,定量限为10 mg/kg,平均回收率为92.0% ~ 101.2%,相对标准偏差为1.02% ~ 5.17%。该方法操作简单,重复性好,准确率高,且上机8 min即可完成替米考星的检测,适用于饲料中替米考星含量的测定。[关键词] 饲料|替米考星|高效液相色谱法 相似文献
94.
95.
MUC4 and MUC13 genes as important candidate genes for enterotoxigenic Escherichia coil (ETEC) F4 resistance,may play an important role in the process of against ETEC F18 infection in weaned piglets. In this study,ETEC F18-resistant and -sensitive weaned Meishan piglets were used,and the expression levels of MUC4 and MUC13 genes in 11 tissues (heart,liver,spleen,lung,kidney,stomach,muscle,thymus,lymph nodes,duodenum and jejunum) were determined by quantitative Real-time PCR. The results showed that MUC4 and MUC13 genes were broadly expressed with different expression levels in all the 11 tissues. In the thymus and lymph tissues,the expression of MUC4 gene in resistant piglets was significantly higher than that in sensitive piglets (P<0.05);In the lung tissue,theMUC13 gene expression level in resistant individuals was significantly higher than that in sensitive individuals (P<0.05),and in the intestinal tissues of duodenum and jejunum, the expression level of MUC13 gene was relatively higher in resistant individuals. Thus we speculated that the high expression of MUC4 gene in immune tissues and MUC13 gene in intestinal tissues might improve the immune ability of piglets,protect and lubricate the intestinal tract, and resist ETEC F18 infection. 相似文献
96.
藏山羊和藏绵羊小肠黏膜免疫相关细胞的比较研究 总被引:1,自引:0,他引:1
为了探讨藏山羊和藏绵羊在低氧环境中小肠黏膜免疫屏障结构的适应特征,本试验采用组织化学方法和图像分析法对4只成年藏山羊和4只成年藏绵羊小肠不同肠段的上皮内淋巴细胞、杯状细胞和肥大细胞的数量进行比较研究。结果显示:藏山羊小肠各段杯状细胞和肥大细胞的数量均高于藏绵羊(P<0.05),其中藏山羊十二指肠、空肠和回肠的上皮内杯状细胞数量分别比藏绵羊多37.87%(P<0.05)、21.43%(P>0.05)和31.68%(P<0.05),藏山羊十二指肠、空肠和回肠的肥大细胞数量分别比藏绵羊多85.20%(P<0.05)、50.73%(P<0.05)和22.52%(P>0.05);而藏山羊小肠各段上皮内淋巴细胞的数量(36.35±0.98)低于藏绵羊(48.84±2.12)(P<0.05)。结果提示,成年藏山羊的小肠黏膜免疫屏障功能强于藏绵羊;藏绵羊小肠中上皮内淋巴细胞起重要的黏膜防御功能,而在藏山羊小肠中杯状细胞和肥大细胞起重要的黏膜防御功能。 相似文献
97.
AIM: To Study the influence of plasma TG level on the contents of serum HDL subpopulations. METHODS: Classified by the contents of serum TG, the serum level of HDL subpopulations in 106 normal TC and 183 high TC subjects were analyzed by two-dimensional gel electrophoresis coupled with immunodection method. RESULTS: The apo-AⅠcontents of per-β1-HDL, HDL3c, HDL3b and HDL3a were higher in a certain extent in TC high subjects vs corresponding TC desirable subjects. The apo-AⅠ contents of per-β1-HDL (in borer-line high TG subgroup) and HDL3b (in very high TG subgroup) were significantly higher (P<0.05 or P<0.01), while the apo-AⅠ contents of HDL2b and HDL2a were all lower in TC high subjects vs corresponding TC normal subjects. With the increase in plasma TG levels, the apoA-Ⅰ content of pre-β1-HDL increased, and it was significantly higher (P<0.05 or P<0.01) in borderline-high TG(except TC desirable subjects), high TG and very high TG subgroups vs corresponding normal TG subgroup. Contents of HDL3b and HDL3a had the same tendency, and in TC high subjects contents of HDL3b (in very high TG subgroup) and HDL3a (in every subgroups, in which levels of TG were higher) were significantly higher (P<0.05 and P<0.01) than in normal TG subgroup. On contrast, the apoA-Ⅰcontents of HDL2b and HDL2a following with the increase of plasma TG levels tended to become lower. Contents of HDL2b were significantly lower (P<0.05) in high TG subgroup and very high TG subgroup vs corresponding normal TG subgroup, and in TC high subjects contents of HDL2a were significantly lower (P<0.05) in very high TG subgroups vs normal TG subgroup. CONCLUSION: Our data show the general shift toward smaller size of HDL particle size with the increase in TC and TG levels. Contents of TC and TG are very important to contents of HDL subclasses. 相似文献
98.
99.
100.
WANG Hai-yan ZOU Zheng-yu DUAN Liang CHEN Xian LI Huan YUAN Shi-mei HE Tong-chuan ZHOU Lan 《园艺学报》2013,29(11):1928-1933
AIM: To investigate the effect of PI3K/Akt signaling pathway on S100A6-induced proliferation and migration of human osteosarcoma cell line 143B. METHODS: Recombinant human S100A6 protein (rhS100A6) was prepared. The 143B cells were treated with rhS100A6 in the presence or absence of PI3K inhibitor (LY294002 or wortmannin) exposure. The final concentrations of rhS100A6, LY294002 and wortmannin were 30 mg/L, 10 μmol/L and 0.5 μmol/L, respectively. The expression levels of total Akt (t-Akt) and phosphorylated Akt (p-Akt) in the 143B cells were analyzed by Western blotting. The cell proliferation and migration were determined by MTT and Transwell assays. RESULTS: rhS100A6 protein was successfully prepared, and significantly increased the proliferation and migration of 143B cells (P<005). rhS100A6 up-regulated the phosphorylation of Akt in 143B cells (P<005). Compared with rhS100A6 group, the level of p-Akt in 143B cells and the proliferation and migration of the cells were decreased in combined treatment group of rhS100A6 with LY294002 or wortmannin (P<005), where the proliferation rate at different time points dropped from 10.3% to 69.7% (P<005), and the migration rate dropped from 34.9% to 47.7% (P<005). CONCLUSION: To some extent, S100A6 promotes proliferation and migration of human ostersarcoma cell line 143B through PI3K/Akt signaling pathway. 相似文献