全文获取类型
收费全文 | 3813篇 |
免费 | 106篇 |
国内免费 | 25篇 |
出版年
2023年 | 14篇 |
2022年 | 51篇 |
2021年 | 64篇 |
2020年 | 26篇 |
2019年 | 26篇 |
2018年 | 25篇 |
2017年 | 37篇 |
2016年 | 264篇 |
2015年 | 985篇 |
2014年 | 1332篇 |
2013年 | 106篇 |
2012年 | 97篇 |
2011年 | 93篇 |
2010年 | 95篇 |
2009年 | 52篇 |
2008年 | 50篇 |
2007年 | 45篇 |
2006年 | 36篇 |
2005年 | 65篇 |
2004年 | 73篇 |
2003年 | 36篇 |
2002年 | 37篇 |
2001年 | 37篇 |
2000年 | 18篇 |
1999年 | 24篇 |
1998年 | 9篇 |
1997年 | 14篇 |
1996年 | 6篇 |
1995年 | 11篇 |
1994年 | 10篇 |
1993年 | 18篇 |
1992年 | 16篇 |
1991年 | 18篇 |
1990年 | 10篇 |
1989年 | 19篇 |
1988年 | 12篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1967年 | 3篇 |
1966年 | 3篇 |
1957年 | 6篇 |
排序方式: 共有3944条查询结果,搜索用时 31 毫秒
101.
The Can Caesar-TonThat Erin Espeland Anthony J. Caesar Upendra M. Sainju Robert T. Lartey John F. Gaskin 《Microbial ecology》2013,66(1):120-131
Stimulation of plant productivity caused by Agaricus fairy rings has been reported, but little is known about the effects of these fungi on soil aggregation and the microbial community structure, particularly the communities that can bind soil particles. We studied three concentric zones of Agaricus lilaceps fairy rings in Eastern Montana that stimulate western wheatgrass (Pascopyrum smithii): outside the ring (OUT), inside the ring (IN), and stimulated zone adjacent to the fungal fruiting bodies (SZ) to determine (1) soil aggregate proportion and stability, (2) the microbial community composition and the N-acetyl-β-d-glucosaminidase activity associated with bulk soil at 0–15 cm depth, (3) the predominant culturable bacterial communities that can bind to soil adhering to wheatgrass roots, and (4) the stimulation of wheatgrass production. In bulk soil, macroaggregates (4.75–2.00 and 2.00–0.25 mm) and aggregate stability increased in SZ compared to IN and OUT. The high ratio of fungal to bacteria (fatty acid methyl ester) and N-acetyl-β-d-glucosaminidase activity in SZ compared to IN and OUT suggest high fungal biomass. A soil sedimentation assay performed on the predominant isolates from root-adhering soil indicated more soil-binding bacteria in SZ than IN and OUT; Pseudomonas fluorescens and Stenotrophomonas maltophilia isolates predominated in SZ, whereas Bacillus spp. isolates predominated in IN and OUT. This study suggests that growth stimulation of wheatgrass in A. lilaceps fairy rings may be attributed to the activity of the fungus by enhancing soil aggregation of bulk soil at 0–15 cm depth and influencing the amount and functionality of specific predominant microbial communities in the wheatgrass root-adhering soil. 相似文献
102.
Nguyen Hoang Loc Le My Tieu Ngoc Tran Thuy Lan Le Quoc Viet Le Duc Thao Hoang Tan Quang Dinh Thi Bich Lan Phung Thang Long 《Indian journal of microbiology》2013,53(4):488-491
We cloned two genes coding F107-C and K88-1NT fimbrial subunits from strains E. coli C and 1NT isolated from Thua Thien Hue province, Vietnam. The mature peptide of faeG gene from strain E. coli 1NT (called faeG-1NT) is 100 % similarity with faeG gene, while the CDS of fedA gene from strain C (called fedA-C) has a similarity of 97 % with the fedA gene. Expression of the faeG-1NT and fedA-C genes in E. coli BL21 Star™ (DE3) produced proteins of ~31 and 22 kDa, respectively. The effect of IPTG concentration on the K88-1NT and F107-C fimbriae production was investigated. The results showed that 0.5 mM IPTG is suitable for higher expression of K88-1NT subunit, while 0.75 mM IPTG strongly stimulated expression of F107-C subunit. The optimal induction time for expression was also examined. Generally, highest expression of K88-1NT subunit occurred after 6 h of induction, while that of F107-C subunit is after 14 h. 相似文献
103.
Nguyen The Tung To Dao Cuong Tran Manh Hung Jeong Hyung Lee Mi Hee Woo Jae Sue Choi Jaewang Kim Sung Ho Ryu Byung Sun Min 《Bioorganic & medicinal chemistry letters》2013,23(5):1428-1432
Four new lanostane triterpenes, butyl lucidenate P (1), butyl lucidenate D2 (2), butyl lucidenate E2 (3) and butyl lucidenate Q (4) along with 11 known compounds (5–15) were isolated from the fruiting bodies of Ganoderma lucidum. Their chemical structures were established mainly by 1D and 2D NMR techniques and mass spectrometry. Their anti-inflammatory activity was evaluated against LPS-induced NO production in macrophage RAW 264.7 cells. Compounds 1, 3, 4, 9, 10 and 15 showed inhibitory potency with IC50 values of 7.4, 6.4, 4.3, 9.4, 9.2 and 4.5 μM, respectively. Compounds 1, 3 and 15 dose-dependently reduced the LPS-induced iNOS expressions. Preincubation of cell with 1, 3 and 15 significantly suppressed LPS-induced expression of COX-2 protein. 相似文献
104.
Thanh Trung Phan Simon James Andrew Turley 《Indian pacing and electrophysiology journal》2013,13(6):221-225
This report describes the successful implantation of a LV lead using balloon venoplasty to overcome a very tight stenosis of the right subclavian vein / brachiocephalic junction for cardiac resynchronisation therapy (CRT-P) in a patient with a right sided CRT-P system and a failed epicardial LV lead. It is important for device implanters to be familiar with interventional equipments and techniques such as balloon venoplasty to overcome difficult venous access. 相似文献
105.
报道了越南木樨科(Oleaceae)植物1 新记录种大果素馨(Jasminum macrocarpum Merr.).该种产自越南中南部嘉来省的K’Bang, Kon Ha Nung 地区, 凭证标本保存在 HN, IBSC. 相似文献
106.
Natural killer (NK) cell malignancies, particularly aggressive NK cell leukaemias and lymphomas, have poor prognoses. Although recent regimens with L-asparaginase substantially improved outcomes, novel therapeutic approaches are still needed to enhance clinical response. Resveratrol, a naturally occurring polyphenol, has been extensively studied for its anti-inflammatory, cardioprotective and anti-cancer activities. In this study, we investigated the potential anti-tumour activities of resveratrol against the NK cell lines KHYG-1, NKL, NK-92 and NK-YS. Resveratrol induced robust G0/G1 cell cycle arrest, significantly suppressed cell proliferation and induced apoptosis in a dose- and time-dependent manner for all four cell lines. In addition, resveratrol suppressed constitutively active STAT3 in all the cell lines and inhibited JAK2 phosphorylation but had no effect on other upstream mediators of STAT3 activation, such as PTEN, TYK2, and JAK1. Resveratrol also induced downregulation of the anti-apoptotic proteins MCL1 and survivin, two downstream effectors of the STAT3 pathway. Finally, resveratrol induced synergistic effect on the apoptotic and antiproliferative activities of L-asparaginase against KHYG-1, NKL and NK-92 cells. These results suggest that resveratrol may have therapeutic potential against NK cell malignancies. Furthermore, our finding that resveratrol is a bonafide JAK2 inhibitor extends its potential benefits to other diseases with dysregulated JAK2 signaling. 相似文献
107.
108.
109.
NIH working group report—using genomic information to guide weight management: From universal to precision treatment 下载免费PDF全文
110.
The relationship of social support with treatment adherence and weight loss in Latinos with type 2 diabetes 下载免费PDF全文