全文获取类型
收费全文 | 31160篇 |
免费 | 1887篇 |
国内免费 | 3119篇 |
专业分类
林业 | 2061篇 |
农学 | 1702篇 |
基础科学 | 1576篇 |
3089篇 | |
综合类 | 15395篇 |
农作物 | 2369篇 |
水产渔业 | 1460篇 |
畜牧兽医 | 4933篇 |
园艺 | 2322篇 |
植物保护 | 1259篇 |
出版年
2024年 | 284篇 |
2023年 | 651篇 |
2022年 | 1488篇 |
2021年 | 1400篇 |
2020年 | 1375篇 |
2019年 | 1250篇 |
2018年 | 941篇 |
2017年 | 1441篇 |
2016年 | 1003篇 |
2015年 | 1533篇 |
2014年 | 1620篇 |
2013年 | 1894篇 |
2012年 | 2671篇 |
2011年 | 2734篇 |
2010年 | 2530篇 |
2009年 | 2260篇 |
2008年 | 2354篇 |
2007年 | 2120篇 |
2006年 | 1761篇 |
2005年 | 1352篇 |
2004年 | 918篇 |
2003年 | 577篇 |
2002年 | 574篇 |
2001年 | 536篇 |
2000年 | 474篇 |
1999年 | 184篇 |
1998年 | 22篇 |
1997年 | 30篇 |
1996年 | 22篇 |
1995年 | 20篇 |
1994年 | 17篇 |
1993年 | 20篇 |
1992年 | 26篇 |
1991年 | 13篇 |
1990年 | 7篇 |
1989年 | 1篇 |
1987年 | 13篇 |
1986年 | 11篇 |
1985年 | 1篇 |
1981年 | 4篇 |
1979年 | 1篇 |
1966年 | 2篇 |
1962年 | 8篇 |
1958年 | 1篇 |
1956年 | 19篇 |
1955年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
LEI Jun-xia LI Hao-wei HUANG Chun-nong ZHU Mei-ling WEN Guan-mei ZHANG Xiu-ming LI Yan LI Shu-nong 《园艺学报》2003,19(10):1325-1330
AIM:To investigate multi-potential of rat bone marrow mesenchymal stem cells (rBMMSC) and mutation inclination, the rBMMSC were long passaged in vitro. METHODS:Cellular cycles of different passages were assayed by FACSan flow cytometry and karyotypes of passage 6, passage 25 and passage 45 were compared by G-binding analysis. RESULTS:The early passages and long-term passages all showed strong proliferation; passage 6, passage 25 and passage 45 all showed normal karyotype. CONCLUSION:Long-term culture and passage of rBMMSC still remains strong proliferation. With this capability, the mutation inclination is not enhanced. 相似文献
42.
AIM:The effects of Yigu capsule on tartrate resistant acid phosphatase (TRAP) secretion and apoptosis in rat osteoclasts were investigated in order to further explore its mechanism of preventing and treating osteoporosis.METHODS:(1) Twenty-month-old Sprague-daweley rats were randomly divided into two groups(Yigu capsule group and saline group), and the drug-containing serum and control serum were prepared. (2) The newborn Sprague-daweley rat osteoclasts were cultured with different concentrations of Yigu capsule drug-containing serum. At different time point, TRAP activity was measured and the survival osteoclast was counted under reverse microscope.The percentage of osteoclast apoptosis was observed under fluorescence microscope after acridine orange staining.RESULTS:TRAP activity was lower and the percentage of osteoclast apoptosis was higher in drug-containing serum group than in control group at 24, 48 and 72 h(P<0.01), respectively, and the survival osteoclasts were less in drug-containing serum group than in control groups at 24, 48 and 72 h(P<0.01).CONCLUSIONS:These data suggest that Yigu capsule drug-containing serum induces apoptosis and inhibits TRAP activity in osteoclasts, which may be one of the mechanisms of Yigu capsule preventing and treating osteoporosis. 相似文献
43.
44.
45.
AIM: To examine the expression of human endostatin in E.coli, produce its fusion protein antibody and observe its biological activity. METHODS: Endostatin gene was amplified by polymerase chain reaction,recombined with plasmid vector pGEX-2T and induced expression with IPTG.The protein activity was tested by endothelial cell proliferation inhibitory assay.Inclusion body crudely purified was used to generate polyclonal antibody to detect its expression at mouse's liver and kidney etc. RESULTS: The protein expressed was 20kD after digestion by thrombin,it appeared the anti-angiogenesis activity and Western blotting indicated the expression of endostatin in liver and kidney of mouse. CONCLUSION: The successful expression of human endostatin and the preparation of polycolonal antibody indicated its potential application in anti-angiogenesis therapy and diagnosis tumors. 相似文献
46.
AIM: To study the electrophysiological characteristics of ion channels of stem cell derived cardiomyocytes(SCDC) of mouse. METHODS: Embryonic stem cells of D3 line(ES-D3) were cultured on the MEF feeder layer with BRL conditioned medium, and fetal mouse heart cells(FMHC)were cultured in vitro. Then ES-D3 cells were induced to differentiate into many kinds of cells. SCDC were harvested on day 12 after differentiation initiating and identified by electro-microscope and immunocytochemistry. SCDC and FMHC were prepared for the patch-clamp research. Sodium and calcium currents together were elicited and compared between SCDC and FMHC. RESULTS: The current characteristics of sodium and calcium channels of SCDC were very similar to FMHC. CONCLUSION: The functional expression of ion channels occurred during ES-D3 cells differentiation and the electrophysiological characteristics of sodium and calcium channels of SCDC are very similar to FMHC. 相似文献
47.
AIM: To investigate the changes of myocardium glycogen content and the relation ship between changes of the myocardial glycogen content and the myocardial function. METHODS: Male Wistar rats were placed in (hypoxia rats) and made to swim in (hypoxia swimming rats) a hypobaxic chamber simulating an altitude of 5 000 m above sea level. The content of myocardium glycogens was determined by colorimetry. RESULTS: The myocardium
glycogen content of rats significantly reduced along with the prolongation of hypoxic exposure and approached to control level in hypoxia swimming rats. The myocardial function of right ventricule was improved significantly compared with control group.CONCLUSION: Moderate exercise (swimming) is beneficial to hypoxic adaptation of rats under the condition of chronic hypoxia. 相似文献
48.
SHANG Zhan-ping HOU Zhong-chi ZHU Shi-gong JI Guo-yi WANG Jian-chun ZHAO Wan 《园艺学报》2002,18(12):1521-1523
AIM: To investigate the activity of interleukin-1β converting enzyme in transplanted intracerebral rat gliomas under angiotensin II-induced hypertension chemotherapy. METHODS: The brain tumor model was produced in Wistar rats by stereotaxic inoculation of C6 glioma cells (1×1012 /L). Tumor-bearing rats were treated with carmustine, teniposide and lisplatin (chemotherapy) during angiotensin II-induced hypertension. Then, the survival time of tumor-bearing rats, tumor blood flow, the concentration of drug, volume of gliomas and the activity of interleukin-1β converting enzyme in glioma were examined.RESULTS: The survival time of tumor-bearing rats was significantly longer in chemotherapy with angiotensin II-induced hypertension group than that of chemotherapy alone. In addition, regional tumor blood flow, the concentration of chemotherapeutic drug and the activity of interleukin -1β converting enzyme in transplanted rat gliomas were increased, while the volume of gliomas was decreased in hypertention chemotherapy group compared with chemotherapy alone. CONCLUSION: Chemotherapy with angiotensin II-induced hypertension has a enhancing effect on chemotherapy for improving the drug delivery to tumor tissue by a increased tumor blood flow and enhancing activity of interleukin -1β converting enzyme. 相似文献
49.
50.
黄花蒿粗提物对几种害虫拒食性的初步研究 总被引:10,自引:0,他引:10
以黄花镐为原料进行浸提,经生物活性测定,结果表明黄花蒿Artenisia annua L.粗提物对供试的6种害虫均具有拒食性。其中对黑翅土白蚁Odontotermes formosanus Shiraki、赤拟谷盗Thibolium castaneum Herbst、谷蠹Rhizopertha dominica Fabricius拒食性极强,对棉蚜Aphis gossypii Glover、棉红蜘蛛Tetranychus urticae Koch及豇豆荚螟Etiella zinckenella Treitschke 也具有较强的巨食性。使用黄花蒿粗提物时,以稀释500倍和800倍效果最好,处理与对照之间有极显著差异。 相似文献