全文获取类型
收费全文 | 8293篇 |
免费 | 423篇 |
国内免费 | 4篇 |
专业分类
8720篇 |
出版年
2024年 | 15篇 |
2023年 | 23篇 |
2022年 | 106篇 |
2021年 | 159篇 |
2020年 | 90篇 |
2019年 | 121篇 |
2018年 | 163篇 |
2017年 | 156篇 |
2016年 | 227篇 |
2015年 | 429篇 |
2014年 | 433篇 |
2013年 | 513篇 |
2012年 | 720篇 |
2011年 | 626篇 |
2010年 | 400篇 |
2009年 | 367篇 |
2008年 | 484篇 |
2007年 | 511篇 |
2006年 | 454篇 |
2005年 | 392篇 |
2004年 | 385篇 |
2003年 | 325篇 |
2002年 | 287篇 |
2001年 | 250篇 |
2000年 | 230篇 |
1999年 | 165篇 |
1998年 | 62篇 |
1997年 | 54篇 |
1996年 | 34篇 |
1995年 | 34篇 |
1994年 | 21篇 |
1993年 | 21篇 |
1992年 | 40篇 |
1991年 | 48篇 |
1990年 | 39篇 |
1989年 | 46篇 |
1988年 | 35篇 |
1987年 | 25篇 |
1986年 | 25篇 |
1985年 | 31篇 |
1984年 | 20篇 |
1983年 | 17篇 |
1981年 | 9篇 |
1979年 | 11篇 |
1978年 | 13篇 |
1977年 | 10篇 |
1974年 | 12篇 |
1973年 | 14篇 |
1972年 | 11篇 |
1971年 | 7篇 |
排序方式: 共有8720条查询结果,搜索用时 15 毫秒
11.
A two-dimensional (2-D) liquid phase separation method, liquid isoelectric focusing followed by nonporous reversed-phase high performance liquid chromatography (HPLC), was used to separate proteins from human ovarian epithelial whole cell lysates. HPLC eluent was interfaced on-line to an electrospray ionization (ESI) time of flight (TOF) mass spectrometer to obtain accurate intact protein molecular weights (Mr). 2-D protein expression maps were generated displaying protein isoelectric point (pI) versus intact protein Mr. Resulting 2-D images effectively displayed quantitative differential protein expression in ovarian cancer cells versus non-neoplastic ovarian epithelial cells. Protein peak fractions were collected from the HPLC eluent, enzymatically digested, and analyzed by matrix-assisted laser desorption/ionization (MALDI) TOF-mass spectrometry (MS) peptide mass fingerprinting and by MALDI-quadrupole TOF tandem mass spectrometry peptide sequencing. Interlysate comparisons of differential protein expression between two ovarian adenocarcinoma cell lines, ES2 and MDAH-2774, and ovarian surface epithelial cells was performed. Five pI fractions from each sample were selected for comparative study and over 300 unique proteins were positively identified from the 2-D liquid expression maps using MS, which covered around 60% of proteins detected by on-line ESI-TOF-MS. This represents one of the most comprehensive proteomic analyses of ovarian cancer samples to date. Protein bands with significant up- or down-regulation in one cell line versus another as viewed in the 2-D expression maps were identified. This strategy may prove useful in identifying novel ovarian cancer marker proteins. 相似文献
12.
Rodearmel SJ Wyatt HR Barry MJ Dong F Pan D Israel RG Cho SS McBurney MI Hill JO 《Obesity (Silver Spring, Md.)》2006,14(8):1392-1401
Objective: Preventing weight gain in adults and excessive weight gain in children is a high priority. We evaluated the ability of a family‐based program aimed at increasing steps and cereal consumption (for breakfast and snacks) to reduce weight gain in children and adults. Research Methods and Procedures: Families (n = 105) with at least one 8‐ to 12‐year‐old child who was at‐risk‐for‐overweight or overweight (designated as the target child) were recruited for the study. Eighty‐two families were randomly assigned to receive the family‐based intervention and 23 families to the control condition. The 13‐week intervention consisted of specific increases in daily steps (an additional 2000 steps/d) and consumption of 2 servings/d of ready‐to‐eat cereal. Results: The intervention was successful in increasing walking (steps) and cereal consumption. The intervention had positive, significant effects on percentage BMI‐for‐age and percentage body fat for target children and weight, BMI, and percentage body fat for parents. On further analysis, the positive effects of the intervention were seen largely in target girls and moms, rather than in target boys and dads. Discussion: This family‐based weight gain prevention program based on small changes holds promise for reducing excessive weight gain in families and especially in growing overweight children. 相似文献
13.
Julie Hoover-Fong Nara Sobreira Julie Jurgens Peggy Modaff Carrie Blout Ann Moser Ok-Hwa Kim Tae-Joon Cho Sung?Yoon Cho Sang?Jin Kim Dong-Kyu Jin Hiroshi Kitoh Woong-Yang Park Hua Ling Kurt?N. Hetrick Kimberly?F. Doheny David Valle Richard?M. Pauli 《American journal of human genetics》2014,94(1):105-112
14.
15.
Baoquan Bao Hung The Dang Ping Zhang Jongki Hong Chong-O. Lee Hee Young Cho Jee H. Jung 《Bioorganic & medicinal chemistry letters》2009,19(21):6205-6208
In the course of our search for bioactive metabolites from a colonial tunicate of the family Polyclinidae, six new (1–6) cyclic fatty acid derivatives were isolated. Their planar structures were established on the basis of NMR and MS spectroscopic analyses. The relative configuration was determined by NOESY experiment. Compounds 1–6 represent a fused bicyclic skeleton possibly derived from α,ω-dicarboxylic acids such as eicosanedioic acid or docosanedioic acid via a Diels–Alder type of cyclization. Compounds 1–4 and 6 showed mild cytotoxicity against a panel of five human solid tumor cell lines. 相似文献
16.
Ahmed H.E. Hassan Min Chang Cho Hye In Kim Ji Seul Yang Kyung Tae Park Ji Young Hwang Choon-Gon Jang Ki Duk Park Yong Sup Lee 《Bioorganic & medicinal chemistry》2018,26(18):5069-5078
CRA13; a peripheral dual CB1R/CB2R agonist with clinically proven analgesic properties, infiltrates into CNS producing adverse effects due to central CB1R agonism. Such adverse effects might be circumvented by less lipophilic compounds with attenuated CB1R affinity. Metabolism produces less lipophilic metabolites that might be active metabolites. Some CRA13 oxidative metabolites and their analogues were synthesized as less lipophilic CRA13 analogues. Probing their CB1R and CB2R activity revealed the alcohol metabolite 8c as a more potent and more effective CB2R ligand with attenuated CB1R affinity relative to CRA13. Also, the alcohol analogue 8b and methyl ester 12a possessed enhanced CB2R affinity and reduced CB1R affinity. The CB2R binding affinity of alcohol analogue 8b was similar to CRA13 while that of methyl ester 12a was more potent. In silico study provided insights into the possible molecular interactions that might explain the difference in the elicited biological activity of these compounds. 相似文献
17.
18.
Jang Hye Jin Choi Ji Yeon Kim Kangjoon Yong Seung Hyun Kim Yeon Wook Kim Song Yee Kim Eun Young Jung Ji Ye Kang Young Ae Park Moo Suk Kim Young Sam Cho Young-Jae Lee Sang Hoon 《Respiratory research》2021,22(1):1-9
IL-35 subunit EBI3 is up-regulated in pulmonary fibrosis tissues. In this study, we investigated the pathological role of EBI3 in pulmonary fibrosis and dissected the underlying molecular mechanism. Bleomycin-induced pulmonary fibrosis mouse model was established, and samples were performed gene expression analyses through RNAseq, qRT-PCR and Western blot. Wild type and EBI3 knockout mice were exposed to bleomycin to investigate the pathological role of IL-35, via lung function and gene expression analyses. Primary lung epithelial cells were used to dissect the regulatory mechanism of EBI3 on STAT1/STAT4 and STAT3. IL-35 was elevated in both human and mouse with pulmonary fibrosis. EBI3 knockdown aggravated the symptoms of pulmonary fibrosis in mice. EBI3 deficiency enhanced the expressions of fibrotic and extracellular matrix-associated genes. Mechanistically, IL-35 activated STAT1 and STAT4, which in turn suppressed DNA enrichment of STAT3 and inhibited the fibrosis process. IL-35 might be one of the potential therapeutic targets for bleomycin-induced pulmonary fibrosis. 相似文献
19.
The platelet microparticle proteome 总被引:4,自引:0,他引:4
Garcia BA Smalley DM Cho H Shabanowitz J Ley K Hunt DF 《Journal of proteome research》2005,4(5):1516-1521
Platelet-derived microparticles are the most abundant type of microparticle in human blood and contribute to many biologically significant processes. Here, we report the first proteomic analysis of microparticles generated from activated platelets. Using 1D SDS-PAGE and liquid chromatography coupled to a linear ion trap mass spectrometer, the identification of 578 proteins was accomplished using a minimum of 5 MS/MS detections of at least two different peptides for each protein. These microparticles displayed many proteins intrinsic to and well-characterized on platelets. For example, microparticles in these experiments were found to contain membrane surface proteins including GPIIIa, GPIIb, and P-selectin, as well other platelet proteins such as the chemokines CXCL4, CXCL7, and CCL5. In addition, approximately 380 of the proteins identified were not found in two previous studies of the platelet proteome. Since several of the proteins detected here have been previously implicated in microparticle formation and/or pathological function, it is hoped that this study will help fuel future work concerning the possible role of microparticles in various disease states. 相似文献
20.
This study was undertaken in order to demonstrate the extent to which the activity of the plasmalemma H+-ATPase compensates for the charge and acidity flow caused by the sugar-proton symport in cells of chlorella vulgaris Beij.. Detailed analysis of H+ and K+ fluxes from and into the medium together with measurements of respiration, cytoplasmic pH, and cellular ATP-levels indicate three consecutive phases after the onset of H+ symport. Phase 1 occurred immediately after addition of sugar, with an uptake of H+ by the hexoseproton symport and charge compensation by K+ loss from the cells and, to a smaller degree, by loss of another ion, probably a divalent cation. This phase coincided with strong membrane depolarization. Phase 2 started approximately 5 s after addition of sugar, when the acceleration of the H+-ATPase caused a slow-down of the K+ efflux, a decrease in the cellular ATP level and an increase in respiration. The increased respiration was most probably responsible for a pronounced net acidification of the medium. This phase was inhibited in deuterium oxide. In phase 3, finally, a slow rate of net H+ uptake and K+ loss was established for several further minutes, together with a slight depolarization of the membrane. There was hardly any pH change in the cytoplasm, because the cytoplasmic buffering capacity was high enough to stabilize the pH for several minutes despite the net H+ fluxes. The quantitative participation of the several phases of H+ and K+ flow depended on the pH of the medium, the ambient Ca2+ concentration, and the metabolic fate of the transported sugar. The results indicate that the activity of the H+-ATPase never fully compensated for H+ uptake by the sugar-symport system, because at least 10% of symport-caused charge inflow was compensated for by K+ efflux. The restoration of pH in the cytoplasm and in the medium was probably achieved by metabolic reactions connected to increased glycolysis and respiration.Abbreviations DMO
dimethyloxazolidinedione
- EDTA
ethylcnediaminetetraacetic acid
- p.c.
packed cell volume 相似文献