全文获取类型
收费全文 | 385篇 |
免费 | 60篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 12篇 |
妇产科学 | 6篇 |
基础医学 | 74篇 |
口腔科学 | 12篇 |
临床医学 | 18篇 |
内科学 | 90篇 |
皮肤病学 | 19篇 |
神经病学 | 7篇 |
特种医学 | 25篇 |
外科学 | 35篇 |
综合类 | 22篇 |
预防医学 | 34篇 |
眼科学 | 8篇 |
药学 | 33篇 |
肿瘤学 | 47篇 |
出版年
2021年 | 5篇 |
2019年 | 5篇 |
2018年 | 12篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2014年 | 9篇 |
2013年 | 6篇 |
2012年 | 9篇 |
2011年 | 15篇 |
2010年 | 9篇 |
2009年 | 11篇 |
2008年 | 12篇 |
2007年 | 15篇 |
2006年 | 10篇 |
2005年 | 12篇 |
2004年 | 7篇 |
2003年 | 11篇 |
2002年 | 12篇 |
2001年 | 14篇 |
2000年 | 10篇 |
1999年 | 17篇 |
1998年 | 8篇 |
1997年 | 13篇 |
1996年 | 9篇 |
1995年 | 6篇 |
1994年 | 10篇 |
1993年 | 6篇 |
1992年 | 15篇 |
1991年 | 13篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 14篇 |
1987年 | 12篇 |
1986年 | 16篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1977年 | 3篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1971年 | 3篇 |
1970年 | 4篇 |
1969年 | 3篇 |
1968年 | 4篇 |
1967年 | 3篇 |
1966年 | 4篇 |
排序方式: 共有445条查询结果,搜索用时 31 毫秒
1.
Summary Bayesian analysis is given of a random effects binary probit model that allows for heteroscedasticity. Real and simulated examples illustrate the approach and show that ignoring heteroscedasticity when it exists may lead to biased estimates and poor prediction. The computation is carried out by an efficient Markov chain Monte Carlo sampling scheme that generates the parameters in blocks. We use the Bayes factor, cross‐validation of the predictive density, the deviance information criterion and Receiver Operating Characteristic (ROC) curves for model comparison. 相似文献
2.
Symptoms of irritable bowel syndrome in a British urban community: consulters and nonconsulters. 总被引:42,自引:0,他引:42
K W Heaton L J O'Donnell F E Braddon R A Mountford A O Hughes P J Cripps 《Gastroenterology》1992,102(6):1962-1967
Because the prevalence of the irritable bowel syndrome (IBS) in the general population is unknown, a questionnaire of intestinal symptoms was administered to a stratified random sample of 1058 women and 838 men. Subjects were asked if they had consulted a physician about such symptoms. One or more symptoms occurred frequently in 47% of women and 27% of men. Diagnosable IBS, defined as three or more symptoms, was present in 13% of women and 5% of men. Abdominal pain was the most common symptom, and recurrent intestinal pain was reported by 20% of women and 10% of men. All symptoms were more common in women except runny or watery stools. Most symptoms including pain were unrelated to age. Only half the people with diagnosable IBS had consulted a physician about it. The likelihood of consulting a physician was directly proportional to the number of symptoms and was similar in men and women after controlling for the number of symptoms. Of individual symptoms, the one most strongly associated with consulting was abdominal pain, especially in men. It is concluded that IBS is prevalent at all ages, especially in women, that it is nearly always painful, and that people with multiple symptoms are more likely to consult a physician. 相似文献
3.
4.
Pulmonary immunity to Pseudomonas aeruginosa in intestinally immunized rats roles of alveolar macrophages, tumor necrosis factor alpha, and interleukin-1 alpha. 下载免费PDF全文
The aims of this study were to assess the role played by alveolar macrophages, tumor necrosis factor alpha (TNF-alpha), and interleukin-1 alpha (IL-1 alpha) in pulmonary immunity against Pseudomonas aeruginosa in animals that have been immunized via the gut-associated lymphoid tissue. Following intra-Peyer's patch immunization and subsequent intratracheal challenge with live bacteria, significantly enhanced bacterial clearance from the lungs correlated with an increase in bronchoalveolar neutrophils, increased recruitment and phagocytic activity of alveolar macrophages, and accelerated production of TNF-alpha in the bronchoalveolar space, while levels of IL-1 alpha remained low. Administration of recombinant TNF-alpha in physiological concentrations did not affect the proliferation of P. aeruginosa in vitro, but when given intratracheally to rats at the time of infection, recombinant TNF-alpha significantly increased bacterial clearance from the lungs. In these animals, phagocytic activity of bronchoalveolar neutrophils was enhanced, while the recruitment of alveolar macrophages and neutrophils remained unchanged. In acutely infected nonimmune animals, bronchoalveolar concentrations of soluble IL-1 alpha and TNF-alpha increased until the time of death. Levels of prostaglandin E2 and thromboxane B2 were similar in each experimental group. These results indicate that infection in immune animals enhanced both recruitment and phagocytic activity of alveolar macrophages as well as induced an accelerated production of TNF-alpha. In immune challenged animals, this cytokine enhanced the phagocytic activity of neutrophils and improved bacterial clearance from the lung. Levels of soluble IL-1 alpha and TNF-alpha in nonimmune rats increased consistently following infection until the time of death, thus implicating these cytokines in the pathogenesis of acute P. aeruginosa pneumonia. 相似文献
5.
CD8+ T cells have an essential role in pulmonary clearance of nontypeable Haemophilus influenzae following mucosal immunization 下载免费PDF全文
A rodent respiratory experimental model has proved useful for investigating the immune mechanisms responsible for clearance of bacteria from the lungs. Immunohistochemical studies in immune and nonimmune rats have identified the cellular kinetics of response to bacterial pulmonary infection for CD8+, CD4+, and gammadelta+ T cells; B cells; and the expression of major histocompatibility complex class II (MHC-II). During the course of bacterial clearance, there was no apparent proliferation or extravasation of lymphocytes, nor was there increased expression of MHC-II in nonimmune animals despite an influx of polymorphonuclear leukocytes, whereas in immunized animals there was an early influx of CD8+ and gammadelta+ T cells, followed by enhanced expression of the MHC-II marker, cellular infiltration by polymorphonuclear leukocytes, and finally an increased number of CD4+ T cells. Depletion of CD8+ T cells confirmed their vital contribution in the preprimed immune response to pulmonary infection by significantly decreasing the animals' ability to clear bacteria following challenge. 相似文献
6.
A possible role for lysozyme in determining acute exacerbation in chronic bronchitis. 总被引:1,自引:0,他引:1 下载免费PDF全文
The aggregation of non-serotypable Haemophilus influenzae (NTHI) by whole saliva from patients with chronic obstructive lung disease (COLD) was investigated. Significant differences were observed between salivary aggregating activity of a control and COLD population (P < 0.001). Saliva from patients less prone to acute exacerbations had a greater capacity to aggregate bacteria compared with saliva from patients with a predilection to infection. The mechanism of saliva-mediated aggregation of NTHI was investigated and shown to be related to lysozyme content. Lysozyme activity in saliva was measured by the turbidimetric technique and results showed that patients with chronic bronchitis had increased levels of salivary lysozyme, with a subpopulation within the non-infection-prone group having greater amounts. A significant difference was observed in salivary lysozyme between controls and non-infection-prone (P < 0.005) and infection-prone (P < 0.05) patients, respectively: the non-infection-prone patients having significantly (P < 0.005) more than the infection-prone patients. There was significant correlation (r = 0.742, P < 0.001) between salivary aggregation of NTHI and lysozyme activity. Chromatographically purified human lysozyme had a similar aggregation profile to that of saliva. There was no difference in serum and saliva lactoferrin concentrations between groups, but there was a significant increase (P < 0.05) in serum lysozyme concentration in the non-infection-prone group. This study suggests that the level of salivary lysozyme derived from macrophages may play an important role in determining resistance or susceptibility to acute bronchitis. 相似文献
7.
An oral killed polyvalent bacterial vaccine was assessed in a double-blind trial involving healthy volunteers. Three courses of oral vaccine were given over a 2-month period; each course contained 10(10) Haemophilus influenzae and 7 X 10(9) Staphylococcus aureus organisms. Immunity was assessed by monitoring antibody in saliva and serum over a 3-month period. No evidence of a nonspecific effect on immune parameters (immunoglobulin levels and Escherichia coli antibody) was detected in saliva or serum. An increase in H. influenzae antibody in saliva was detected in 55% of subjects receiving the vaccine compared with 6.7% of the placebo group. Antibody was associated with immunoglobulin A (IgA), IgG, and IgM, but the greatest increases over preimmunization levels were detected in the IgA class. No increase in serum antibody levels was detected. Subjects with higher preimmunization levels of salivary antibody to H. influenzae were less likely to respond to the oral bacterial vaccine. No increase in S. aureus antibody was detected in saliva or serum. 相似文献
8.
G A Stewart K J Turner B A Baldo A W Cripps A Ford V Seagroatt H Lowenstein A K Ekramoddoullah 《International archives of allergy and applied immunology》1988,86(1):9-18
Six candidate extracts of Lolium perenne (rye-grass) pollen have been studied in 6 laboratories using a variety of immunochemical and physicochemical techniques. Radioallergosorbent test inhibition, crossed immunoelectrophoresis, crossed radio-immunoelectrophoresis, sodium dodecyl sulphate-polyacrylamide gel electrophoresis combined with immunoblot, thin-layer isoelectric focusing and enzyme-linked immunosorbent assay inhibition were used to evaluate each of the coded extracts. The source materials were also studied for identity and possible contamination by light microscopy. On the basis of these data, the Rye-Grass Working Party recommended to the Steering Committee of the Allergen Standardization Subcommittee of the International Union of Immunological Societies that the extract coded C be chosen as the candidate international reference preparation. 相似文献
9.
10.