全文获取类型
收费全文 | 917篇 |
免费 | 65篇 |
国内免费 | 1篇 |
专业分类
983篇 |
出版年
2023年 | 8篇 |
2022年 | 15篇 |
2021年 | 27篇 |
2020年 | 6篇 |
2019年 | 16篇 |
2018年 | 24篇 |
2017年 | 16篇 |
2016年 | 33篇 |
2015年 | 48篇 |
2014年 | 38篇 |
2013年 | 63篇 |
2012年 | 82篇 |
2011年 | 69篇 |
2010年 | 40篇 |
2009年 | 42篇 |
2008年 | 39篇 |
2007年 | 45篇 |
2006年 | 48篇 |
2005年 | 42篇 |
2004年 | 29篇 |
2003年 | 37篇 |
2002年 | 27篇 |
2001年 | 19篇 |
2000年 | 17篇 |
1999年 | 10篇 |
1998年 | 5篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 9篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 8篇 |
1973年 | 9篇 |
1971年 | 3篇 |
1970年 | 3篇 |
1965年 | 3篇 |
1950年 | 2篇 |
排序方式: 共有983条查询结果,搜索用时 15 毫秒
41.
Causes for the death of the eggs in the prawn Macrobrachium nobilii are: i) shedding of eggs by ovigerous female, and ii) infection by epibionts: a Saprolegnial fungus, bacteria (gram negative) and protozoans (Vorticellids and Paramecium). A cause for the death of freshly hatched larvae of some decapods is the reduction in reserve yolk energy in the larvae hatched in the last few batches. To circumvent these disadvantages, an artificial incubator was designed, in which 70% of the 3-day old eggs can successfully be incubated and hatched simultaneously. The isolted eggs are irrigated with filtered and aerated water over a diaphragm in the incubator; the water flushed from below through the diaphragm in the artificial incubator, sways and keeps the eggs continuously in a suspended motion, simulating the irrigation technique of the mother.Presented in the Second International Symposium on Invertebrate Reproduction held in Davis, California during August, 1979 相似文献
42.
Sunil Kumar GB Ganapathi TR Revathi CJ Prasad KS Bapat VA 《Protein expression and purification》2003,32(1):10-17
Hepatitis B virus ' s ' gene coding for surface antigen was cloned into plant transformation vectors pHER100 and pHBs100 with and without endoplasmic reticulum retention signal, respectively. Transformed tobacco cell lines were analyzed for the integration of the transgene by PCR and Southern blot hybridization. Expression levels as determined by ELISA showed maximum expression levels of 2 microg HBsAg gm(-1) fresh weight and 10 ng mL(-1) of spent medium in pHER100 transformed cells. Western blot analysis confirmed the presence of 24 kDa band specific to HBsAg in the transformed cells. HBsAg was expressed both as intracellular and secreted forms in pHER100 transformed cells. The buoyant density in CsCl of HBsAg derived from pHBs100 transformed tobacco cells was determined and found to be 1.095 g mL(-1). HBsAg obtained from transformed tobacco cells is similar to the human serum derived one in buoyant density properties. This is the first report on the secretion of HBsAg particles by plant cells into the cell culture medium. 相似文献
43.
Vidyavathi Reddy Min Wu Nicholas Ciavattone Nathan McKenty Mani Menon Evelyn R. Barrack G. Prem-Veer Reddy Sahn-Ho Kim 《The Journal of biological chemistry》2015,290(42):25522-25533
Androgen receptor (AR) plays a role in maintaining telomere stability in prostate cancer cells, as AR inactivation induces telomere dysfunction within 3 h. Since telomere dysfunction in other systems is known to activate ATM (ataxia telangiectasia mutated)-mediated DNA damage response (DDR) signaling pathways, we investigated the role of ATM-mediated DDR signaling in AR-inactivated prostate cancer cells. Indeed, the induction of telomere dysfunction in cells treated with AR-antagonists (Casodex or MDV3100) or AR-siRNA was associated with a dramatic increase in phosphorylation (activation) of ATM and its downstream effector Chk2 and the presenceof phosphorylated ATM at telomeres, indicating activation of DDR signaling at telomeres. Moreover, Casodex washout led to the reversal of telomere dysfunction, indicating repair of damaged telomeres. ATM inhibitor blocked ATM phosphorylation, induced PARP cleavage, abrogated cell cycle checkpoint activation and attenuated the formation of γH2AX foci at telomeres in AR-inactivated cells, suggesting that ATM inhibitor induces apoptosis in AR-inactivated cells by blocking the repair of damaged DNA at telomeres. Finally, colony formation assay revealed a dramatic decrease in the survival of cells co-treated with Casodex and ATM inhibitor as compared with those treated with either Casodex or ATM inhibitor alone. These observations indicate that inhibitors of DDR signaling pathways may offer a unique opportunity to enhance the potency of AR-targeted therapies for the treatment of androgen-sensitive as well as castration-resistant prostate cancer. 相似文献
44.
45.
46.
Xia CQ Peng R Annamalai M Clare-Salzler MJ 《Biochemical and biophysical research communications》2007,352(4):960-965
Mature dendritic cells (mDCs) undergo "exhaustion" in producing cytokines. Nevertheless, whether this "exhaustion" of mDCs is selective to certain cytokines, or whether mDCs have specific cytokine-producing profiles has yet to be defined. Herein, we investigated the cytokine production in vitro by immature DCs (iDCs) and LPS-induced mDCs. Compared to iDCs, mDCs produced comparable levels of IL-6 and TNF-alpha. Strikingly, mDCs produced significantly higher IFN-gamma and IL-10. IL-12 production of mDCs was suppressed. Kinetic studies of the responses of iDCs and mDCs to LPS or CD40L showed that mDCs acquired progressively heightened activity in producing IFN-gamma and IL-10. TNF-alpha-, IL-6-producing capability of mDCs was maintained. Nevertheless, IL-12 production by mDCs was not recovered at any time point. Mature DCs were potent in priming both Th1 and Th2 cells. In conclusion, upon maturation, DCs are reprogrammed with a distinct cytokine-secreting profile, which may play an important role in regulating T cell functions. 相似文献
47.
Kamlesh Khunti Hamidreza Mani Felix Achana Nicola Cooper Laura J. Gray Melanie J. Davies 《PloS one》2015,10(9)
Background
Screening for type 2 diabetes (T2DM) and individuals at risk of diabetes has been advocated, yet information on the response rate and diagnostic yield of different screening strategies are lacking.Methods
Studies (from 1998 to March/2015) were identified through Medline, Embase and the Cochrane library and included if they used oral glucose tolerance test (OGTT) and WHO-1998 diagnostic criteria for screening in a community setting. Studies were one-step strategy if participants were invited directly for OGTT and two, three/four step if participants were screened at one or more levels prior to invitation to OGTT. The response rate and diagnostic yield were pooled using Bayesian random-effect meta-analyses.Findings
47 studies (422754 participants); 29 one-step, 11 two-step and seven three/four-step were identified. Pooled response rate (95% Credible Interval) for invitation to OGTT was 65.5% (53.7, 75.6), 63.1% (44.0, 76.8), and 85.4% (76.4, 93.3) in one, two and three/four-step studies respectively. T2DM yield was 6.6% (5.3, 7.8), 13.1% (4.3, 30.9) and 27.9% (8.6, 66.3) for one, two and three/four-step strategies respectively. The number needed to invite to the OGTT to detect one case of T2DM was 15, 7.6 and 3.6 in one, two, and three/four-step strategies. In two step strategies, there was no difference between the response or yield rates whether the first step was blood test or risk-score. There was evidence of substantial heterogeneity in rates across study populations but this was not explained by the method of invitation, study location (rural versus urban) and developmental index of the country in which the study was performed.Conclusions
Irrespective of the invitation method, developmental status of the countries and or rural/urban location, using a multi-step strategy increases the initial response rate to the invitation to screening for diabetes and reduces the number needed to have the final diagnostic test (OGTT in this study) for a definite diagnosis. 相似文献48.
49.
Pierre Neuvial Philippe Hupé Isabel Brito Stéphane Liva élodie Manié Caroline Brennetot Fran?ois Radvanyi Alain Aurias Emmanuel Barillot 《BMC bioinformatics》2006,7(1):264
Background
Array-based comparative genomic hybridization (array-CGH) is a recently developed technique for analyzing changes in DNA copy number. As in all microarray analyses, normalization is required to correct for experimental artifacts while preserving the true biological signal. We investigated various sources of systematic variation in array-CGH data and identified two distinct types of spatial effect of no biological relevance as the predominant experimental artifacts: continuous spatial gradients and local spatial bias. Local spatial bias affects a large proportion of arrays, and has not previously been considered in array-CGH experiments. 相似文献50.