全文获取类型
收费全文 | 312篇 |
免费 | 40篇 |
国内免费 | 1篇 |
专业分类
353篇 |
出版年
2022年 | 2篇 |
2021年 | 7篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 12篇 |
2014年 | 12篇 |
2013年 | 19篇 |
2012年 | 20篇 |
2011年 | 15篇 |
2010年 | 16篇 |
2009年 | 17篇 |
2008年 | 15篇 |
2007年 | 16篇 |
2006年 | 15篇 |
2005年 | 11篇 |
2004年 | 16篇 |
2003年 | 13篇 |
2002年 | 9篇 |
2001年 | 14篇 |
2000年 | 15篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1996年 | 3篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1979年 | 4篇 |
1977年 | 2篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1972年 | 4篇 |
1970年 | 2篇 |
1967年 | 3篇 |
1966年 | 2篇 |
1957年 | 1篇 |
1940年 | 1篇 |
1938年 | 2篇 |
1936年 | 1篇 |
1932年 | 1篇 |
排序方式: 共有353条查询结果,搜索用时 0 毫秒
81.
A selective IKK-2 inhibitor blocks NF-kappa B-dependent gene expression in interleukin-1 beta-stimulated synovial fibroblasts 总被引:12,自引:0,他引:12
82.
83.
Using the historical population of Gibraltar to examine the pattern of mortality of Jews and Roman Catholics revealed that: (1) the Jews exhibited a significantly better health status as measured by life expectancy at birth (47.66 and 47.56 for Jewish males and females vs. 38.10 and 40.89 for Catholics males and females, respectively), (2) most of the disparity is found in the very young age categories and (3) the significantly lower rates of deaths could be attributed to the diarrheal and nutritional complex. Stage two of the research involved the linkage of deaths over a 7-year period relative to their household context as of 1878. Being Jewish, having a servant, having access to a water well in the tenement and residing in a tenement only with other Jews, were all factors that contributed to a higher life expectancy. Our explanation for the enhanced survivorship among the Jews is grounded in economics as well as in an established welfare system, in religious precepts and in secular knowledge of health. One of the more notable and hitherto unobserved findings is that Roman Catholics residing in the same tenements with Jews enjoyed a distinct health advantage. This suggests that a positive amplification effect arose from their co-residence with the Jews. 相似文献
84.
The introduction of exogenous DNA into Escherichia coli is a cornerstone of molecular biology. Herein, we investigate two new mechanisms for bacterial transformation involving either the use of microwave irradiation or a freeze–thaw protocol in liquid nitrogen. Ultimately, both methods afforded successful transfer of plasmid DNA into bacterial cells, with the freeze–thaw technique yielding efficiencies of ~105. More importantly, both techniques effectively eliminated the need for the preparation of competent cells. 相似文献
85.
The small-subunit ribosomal RNA gene sequences from the hypotrichous ciliates Oxytricha nova and Stylonychia pustulata 总被引:17,自引:0,他引:17
We have determined the complete nucleotide sequence of the small- subunit
ribosomal RNA genes for the ciliate protozoans Stylonychia pustulata and
Oxytricha nova. The sequences are homologous and sufficiently similar that
these organisms must be closely related. In a phylogeny inferred from
comparisons of several eukaryotic small-subunit ribosomal RNAs, the
divergence of the ciliates from the eukaryotic line of descent is seen to
coincide with the radiation of the plants, the animals, and the fungi. This
radiation is preceded by the divergence of the slime mold, Dictyostelium
discoideum.
相似文献
86.
Niels H Chavannes Juanita HJ Vernooy Tjard RJ Schermer Jan A Jacobs Mieke A Dentener Chris van Weel Onno CP van Schayck Emiel FM Wouters 《BMC pulmonary medicine》2006,6(1):1-7
Background
Although both smoking and respiratory complaints are very common, tools to improve diagnostic accuracy are scarce in primary care. This study aimed to reveal what inflammatory patterns prevail in clinically established diagnosis groups, and what factors are associated with eosinophilia.Method
Induced sputum and blood plasma of 59 primary care patients with COPD (n = 17), asthma (n = 11), chronic bronchitis (CB, n = 14) and smokers with no respiratory complaints ('healthy smokers', n = 17) were collected, as well as lung function, smoking history and clinical work-up. Patterns of inflammatory markers per clinical diagnosis and factors associated with eosinophilia were analyzed by multiple regression analyses, the differences expressed in odds ratios (OR) with 95% confidence intervals.Results
Multivariately, COPD was significantly associated with raised plasma-LBP (OR 1.2 [1.04–1.37]) and sTNF-R55 in sputum (OR 1.01 [1.001–1.01]), while HS expressed significantly lowered plasma-LBP (OR 0.8 [0.72–0.95]). Asthma was characterized by higher sputum eosinophilic counts (OR 1.3 [1.05–1.54]), while CB showed a significantly higher proportion of sputum lymphocytic counts (OR 1.5 [1.12–1.9]). Sputum eosinophilia was significantly associated with reversibility after adjusting for smoking, lung function, age, gender and allergy.Conclusion
Patterns of inflammatory markers in a panel of blood plasma and sputum cells and mediators were discernable in clinical diagnosis groups of respiratory disease. COPD and so-called healthy smokers showed consistent opposite associations with plasma LBP, while chronic bronchitics showed relatively predominant lymphocytic inflammation compared to other diagnosis groups. Only sputum eosinophilia remained significantly associated with reversibility across the spectrum of respiratory disease in smokers with airway complaints. 相似文献87.
CD40 ligand (CD154) enhances the Th1 and antibody responses to respiratory syncytial virus in the BALB/c mouse 总被引:2,自引:0,他引:2
Tripp RA Jones L Anderson LJ Brown MP 《Journal of immunology (Baltimore, Md. : 1950)》2000,164(11):5913-5921
CD40 ligand (CD40L) is a cell surface costimulatory molecule expressed mainly by activated T cells. CD40L is critically important for T-B cell and T cell-dendritic cell interactions. CD40L expression promotes Th1 cytokine responses to protein Ags and is responsible for Ig isotype switching in B cells. Respiratory syncytial virus (RSV) is an important pathogen of young children and the elderly, which causes bronchiolitis and pneumonia. Studies of mice infected with RSV suggest that a Th2 cytokine response may be responsible for enhanced pulmonary disease. To investigate the effect CD40L has on RSV immunity, mice were infected simultaneously with RSV and either an empty control adenovirus vector or one expressing CD40L or were coimmunized with plasmid DNA vectors expressing CD40L and RSV F and/or G proteins and subsequently challenged with RSV. The kinetics of the intracellular and secreted cytokine responses, the cytotoxic T lymphocyte precursor frequency, NO levels in lung lavage, rates of virus clearance, and anti-RSV Ab titers were determined. These studies show that coincident expression of CD40L enhances the Th1 (IL-2 and IFN-gamma) cytokine responses, increases the expression of TNF-alpha and NO, accelerates virus clearance, and increases the anti-F and anti-G Ab responses. These data suggest that CD40L may have the adjuvant properties needed to optimize the safety and efficacy of RSV vaccines. 相似文献
88.
Invasive silver carp (Hypothalmichthys molitrix) occurs throughout much of the Mississippi River and threatens the Laurentian Great Lakes. To quantify habitat selection
relative to river flow and potential phytoplankton food, 77 adult silver carp were implanted with ultrasonic transmitters
during spring 2008 through spring 2009 in adjacent upstream dammed and downstream undammed reaches (48 km total) of the Mississippi
River. Sixty-seven percent of the fish were located. Selection of major river habitat features (dammed vs. undammed, backwaters,
channel border, wing dikes, island side channels, and the main channel) was quantified. Flow rates and chlorophyll a concentration were compared between silver carp locations and random sites. Foregut chlorophyll a concentrations plus presence of macrozooplankton and detritus of 240 non-tagged silver carp were quantified. About 30% of
silver carp moved upstream into the dammed reach, where average flow was slower and chlorophyll a concentration was higher. Silver carp selected wing dike areas of moderate flow (about 0.3 m/s) and elevated chlorophyll
a (about 7 μg/L) relative to random sites. No silver carp occurred in areas where flow was absent. Wing dikes were preferred
while the main channel was avoided. Chlorophyll a concentrations in guts were positively related to temperature and were unrelated to flow or river chlorophyll a concentration. Macrozooplankton and detritus were rare in guts. Silver carp seek areas of low flow and successfully forage
across a range of temperatures, flows, and chlorophyll a concentrations that occur in rivers and large lakes. 相似文献
89.
Mary J. Hauser Daniel Dlugolenski Marie R. Culhane David E. Wentworth S. Mark Tompkins Ralph A. Tripp 《PloS one》2013,8(7)
Swine generate reassortant influenza viruses because they can be simultaneously infected with avian and human influenza; however, the features that restrict influenza reassortment in swine and human hosts are not fully understood. Type I and III interferons (IFNs) act as the first line of defense against influenza virus infection of respiratory epithelium. To determine if human and swine have different capacities to mount an antiviral response the expression of IFN and IFN-stimulated genes (ISG) in normal human bronchial epithelial (NHBE) cells and normal swine bronchial epithelial (NSBE) cells was evaluated following infection with human (H3N2), swine (H1N1), and avian (H5N3, H5N2, H5N1) influenza A viruses. Expression of IFNλ and ISGs were substantially higher in NHBE cells compared to NSBE cells following H5 avian influenza virus infection compared to human or swine influenza virus infection. This effect was associated with reduced H5 avian influenza virus replication in human cells at late times post infection. Further, RIG-I expression was lower in NSBE cells compared to NHBE cells suggesting reduced virus sensing. Together, these studies identify key differences in the antiviral response between human and swine respiratory epithelium alluding to differences that may govern influenza reassortment. 相似文献
90.
Denise Daley Mathieu Lemire Loubna Akhabir Moira Chan-Yeung Jian Qing He Treena McDonald Andrew Sandford Dorota Stefanowicz Ben Tripp David Zamar Yohan Bosse Vincent Ferretti Alexandre Montpetit Marie-Catherine Tessier Allan Becker Anita L. Kozyrskyj John Beilby Pamela A. McCaskie Bill Musk Nicole Warrington Alan James Catherine Laprise Lyle J. Palmer Peter D. Paré Thomas J. Hudson 《Human genetics》2009,125(4):445-459