全文获取类型
收费全文 | 4868篇 |
免费 | 411篇 |
国内免费 | 13篇 |
专业分类
耳鼻咽喉 | 37篇 |
儿科学 | 170篇 |
妇产科学 | 103篇 |
基础医学 | 580篇 |
口腔科学 | 115篇 |
临床医学 | 558篇 |
内科学 | 1058篇 |
皮肤病学 | 39篇 |
神经病学 | 436篇 |
特种医学 | 181篇 |
外科学 | 764篇 |
综合类 | 87篇 |
一般理论 | 3篇 |
预防医学 | 367篇 |
眼科学 | 111篇 |
药学 | 294篇 |
中国医学 | 6篇 |
肿瘤学 | 383篇 |
出版年
2021年 | 81篇 |
2020年 | 56篇 |
2019年 | 64篇 |
2018年 | 73篇 |
2017年 | 66篇 |
2016年 | 53篇 |
2015年 | 70篇 |
2014年 | 99篇 |
2013年 | 208篇 |
2012年 | 196篇 |
2011年 | 213篇 |
2010年 | 130篇 |
2009年 | 95篇 |
2008年 | 164篇 |
2007年 | 198篇 |
2006年 | 179篇 |
2005年 | 191篇 |
2004年 | 181篇 |
2003年 | 171篇 |
2002年 | 155篇 |
2001年 | 169篇 |
2000年 | 171篇 |
1999年 | 128篇 |
1998年 | 46篇 |
1997年 | 32篇 |
1996年 | 64篇 |
1995年 | 58篇 |
1994年 | 56篇 |
1993年 | 46篇 |
1992年 | 139篇 |
1991年 | 130篇 |
1990年 | 119篇 |
1989年 | 138篇 |
1988年 | 123篇 |
1987年 | 121篇 |
1986年 | 106篇 |
1985年 | 112篇 |
1984年 | 84篇 |
1983年 | 61篇 |
1982年 | 39篇 |
1980年 | 38篇 |
1979年 | 74篇 |
1978年 | 39篇 |
1977年 | 41篇 |
1976年 | 54篇 |
1975年 | 40篇 |
1974年 | 31篇 |
1972年 | 39篇 |
1971年 | 39篇 |
1970年 | 33篇 |
排序方式: 共有5292条查询结果,搜索用时 20 毫秒
61.
Serum prealbumin and retinol-binding protein in the prealbumin-related senile and familial forms of systemic amyloidosis 总被引:4,自引:0,他引:4
P Westermark P Pitk?nen L Benson A Vahlquist B O Olofsson G G Cornwell 《Laboratory investigation; a journal of technical methods and pathology》1985,52(3):314-318
In a series of 13 elderly patients with proven prealbumin-related senile systemic amyloidosis (SSA), depressed serum prealbumin values (110.7 +/- 14.1 micrograms/ml) were found as compared to an age-matched control group (175.1 +/- 20.3 micrograms/ml). As expected, there was a significant correlation between serum prealbumin and serum retinol-binding proteins in both groups of patients. Patients with reactive amyloid protein AA amyloidosis had slightly depressed serum prealbumin concentrations, whereas patients with prealbumin-related familial amyloidosis of Swedish type had prealbumin values within normal limits. Since the serum levels of the acute phase reactants, haptoglobin and amyloid-related serum protein AA, were higher in the group of patients with reactive amyloidosis than in patients with SSA, the depression of the prealbumin levels in SSA is not a result of inflammation. Since SSA is known to contain prealbumin, it is possible that a disturbed prealbumin metabolism in old age results in low prealbumin serum values and deposition of amyloid. 相似文献
62.
Myrin Borysenko Samuel Turesky Joan Z. Borysenko Fred Quimby Herbert Benson 《Journal of behavioral medicine》1980,3(3):233-243
The stress of crowding and exposure to inescapable electric shock increased both the incidence and the severity of dental caries in rats housed in a conventional animal facility. Male Osborne-Mendel rats were inoculated intraorally with cariogenic bacteria, fed a high-sucrose diet, and housed in either a conventional or a sheltered facility. Rats in both housing conditions were subdivided into control and stress groups. At the end of the 56-day trial period, stressed rats from conventional housing had a significant increase in both incidence and severity of dental caries in comparison to their controls. In contrast, stressed rats from sheltered housing had a trend toward increased cariogenesis which reached significance in only one of five scores. These rats also failed to gain weight comparable to their controls, making it possible that stress-induced reduction in appetite partially offset stress-induced exacerbation in cariogenesis.This investigation was supported in part by the following Grants from the United States Public Health Service: CA 20093, HL 22727, and HL 07374. 相似文献
63.
Expanded school mental health (ESMH) programs involve the provision of comprehensive mental health services for youth in schools, including assessment, intervention, prevention, and consultation. Related to increased awareness of the benefits of these programs, and growing disenchantment with traditional forms of mental health service delivery for children, ESMH programs are growing rapidly in the United States. Coinciding with the growth of these programs is a developing interface between and among education and mental health professionals in schools. In this interface, there is an increasing need for real collaboration; however, associated with differences in professional training, language, and expectations, and related to "turf," such collaboration is often an elusive prospect. In this article, we review historical trends that provide background to the growing education-mental health interface in schools. We discuss tensions that arise between staff of various disciplines when ESMH programs are developed, and provide recommendations on strategies to develop truly collaborative approaches to the provision of comprehensive mental health services in schools. 相似文献
64.
Adult male mice were exposed to either alternating illumination or constant illumination for 70 days. Light and dark pinealocytes were compared as to distribution within the gland and ultrastructure. Quantitative studies with the electron microscope revealed a significant reduction in pinealocyte size and Golgi complex size in constant light treatment, as well as a marked but nonsignificant reduction in the concentration of lipid droplets and irregular vacuoles. Under constant light treatment the cross-sectional area of pinealocyte pericapillary terminals and the number of granulated vesicles per terminal decreased significantly. A greater number of mitochondria appeared swollen, with rarified matrix and reduced numbers of cristae, with constant light treatment. These results provide ultrastructural correlation with the known reduction of pineal weight, protein synthesis and antigonadotrophic activity that is seen with constant light treatment. The marked decrease in concentration of pinealocyte granulated vesicles in constant light treatment gives morphological support to the theory that these vesicles contain antigonadotrophic secretory material. 相似文献
65.
H H Harrison E D Gordon W C Nichols M D Benson 《American journal of medical genetics》1991,39(4):442-452
We report identification, biochemical, clinical, and genetic studies of an apparently benign, electrophoretic variant of serum prealbumin (PALB, transthyretin, TTR) in a North American kindred of Swedish ancestry. The variant polypeptide stems from a C to T point mutation in exon 4 which results in methionine instead of threonine at position 119 of the mature molecule. It was discovered incidentally in a girl with classic alpha-1-anti-trypsin (A1AT) deficiency and her father during diagnostic A1AT phenotyping by ISO-DALT high-resolution two-dimensional electrophoresis (2DE). Twelve relatives in the four-generation paternal kindred, including five individuals who were heterozygous for the variant prealbumin, were studied. In each of these five heterozygotes, the variant allele product was equimolar and isoelectric with the normal protein, yet migrated with an apparently lower mass in the SDS-PAGE dimension. The inheritance pattern was consistent with autosomal dominant transmission. Histories and physical examinations showed no evidence of amyloidosis, as has been observed with other variants of prealbumin. Mean values of serum prealbumin and retinol binding protein levels were higher in the carriers as compared to the normal relatives in the family, but the difference was not statistically significant. Thyroid hormone levels and distribution of thyroxine and triiodothyronine among binding proteins in serum were within reference limits. Four members of the lineage had dominant, scalp-restricted keratinaceous cysts, yet only three of these four individuals had the variant. We counseled the family that this is likely a benign variant with regard to amyloidosis-related morbidity or shortened life span, although senile effects cannot be entirely ruled out. The provisional designation assigned to this allele is PALBCHICAGO. The substitution of methionine at position 119, as predicted by the DNA sequence, was confirmed by amino acid sequencing of CNBr and tryptic peptides. This substitution occurs at a CpG dinucleotide that may be a point mutational "hot spot," as has been postulated for the methionine-30 and isoleucine-122 PALB variants. The apparently lower mass of the variant probably results from a more compact conformation in SDS. With the exception of histidine-58, a charge substitution, all other amyloidosis-related prealbumin variant polypeptides had normal mobility in the ISO-DALT 2DE system. 相似文献
66.
Quinupristin-dalfopristin-resistant Enterococcus faecium on chicken and in human stool specimens 总被引:1,自引:0,他引:1
McDonald LC Rossiter S Mackinson C Wang YY Johnson S Sullivan M Sokolow R DeBess E Gilbert L Benson JA Hill B Angulo FJ 《The New England journal of medicine》2001,345(16):1155-1160
BACKGROUND: The combination of the streptogramins quinupristin and dalfopristin was approved in the United States in late 1999 for the treatment of vancomycin-resistant Enterococcus faecium infections. Since 1974, another streptogramin, virginiamycin, has been used at subtherapeutic concentrations to promote the growth of farm animals, including chickens. METHODS: To determine the frequency of quinupristin-dalfopristin-resistant E. faecium, we used selective medium to culture samples from chickens purchased in supermarkets in Georgia, Maryland, Minnesota, and Oregon and stool samples from outpatients. RESULTS: Between July 1998 and June 1999, samples from 407 chickens from 26 stores in four states were cultured, as were 334 stool samples from outpatients. Quinupristin-dalfopristin-resistant E. faecium was isolated from 237 chicken carcasses and 3 stool specimens. The resistant isolates from stool had low-level resistance (minimal inhibitory concentration [MIC], 4 microg per milliliter; resistance was defined as a MIC of at least 4 microg per milliliter). The resistant isolates from chickens in general had higher levels of resistance (MICs ranging from 4 to 32 microg per milliliter; MIC required to inhibit 50 percent of isolates, 8 microg per milliliter). CONCLUSIONS: Quinupristin-dalfopristin-resistant E. faecium contaminates a large proportion of chickens sold in U.S. supermarkets. However, the low prevalence and low level of resistance of these strains in human stool specimens suggest that the use of virginiamycin in animals has not yet had a substantial influence. Foodborne dissemination of resistance may increase, however, as the clinical use of quinupristin-dalfopristin increases. 相似文献
67.
BACKGROUND: Increased levels of allergen-reactive immunoglobulins (Igs) have been reported in nasal fluids from patients with intermittent allergic rhinitis (IAR) sensitive to ragweed and grass. The aims of this study were to make a detailed characterization of nasal fluid Igs in birch pollen-induced IAR. METHODS: Nasal fluids were obtained from 23 patients with birch pollen-induced IAR during and after the birch pollen season, and from 20 healthy controls. Nasal fluid total and Bet v 1-reactive (IgA), IgE and IgG as well as albumin were analyzed by immunoassays. The integrity of IgA and IgG, and the molecular form of IgA were assessed by Western blotting and column fractionation, respectively. RESULTS: Nasal fluid total IgE and IgG, but not IgA, were higher in patients compared with controls. Western blotting indicated no significant degradation of IgA (including S-IgA) and IgG. Most of the IgA, including Bet v 1-reactive antibodies, was of the secretory form and of the IgA1 subclass. Bet v 1-reactive IgA and IgG were present in all patients, but was mostly nondetectable in controls. No significant differences in the levels of Bet v 1-reactive IgA and IgG were found in patients during the birch pollen season compared with off season. Both Bet v 1 and Bet v 2-reactive IgE were nondetectable in most samples. CONCLUSIONS: Nasal fluid Bet v 1-reactive IgA and IgG were found in all patients with birch pollen-induced IAR, but not in controls. However, no significant differences were found between patients during and after the birch pollen season. 相似文献
68.
Brown DT Benson AJ Walker NW Sternberger LG Lung DS Kassinove H 《Journal of clinical psychology》2004,60(10):1091-1108
This article was developed in response to the proceedings of the Consensus Conference on Combined and Integrated Doctoral Training in Psychology held at James Madison University in Harrisonburg, VA, May 2 to 4, 2003. The authors approach the recommendations of the conference from the perspective of their experiences in higher education administration at the national, regional, and state levels. The authors conclude that the Consensus Conference represents an exemplar of best practice in program planning. They suggest that a major reconceptualization of higher education is under way that emphasizes broad collaboration among various professional groups as a means of providing appropriate mental health and health care services. Consequently, professional psychology will need to reconceptualize its role in the broader context of other professions within the university setting. Recommendations for the education of psychologists and the development of future training programs are provided. Suggestions for implementation of various recommendations flowing from the Consensus Conference are delineated. 相似文献
69.
X-linked agammaglobulinemia (XLA) is an immunodeficiency caused by mutations in the Bruton tyrosine kinase (BTK) gene. Twenty Australian patients with an XLA phenotype, from 15 unrelated families, were found to have 14 mutations. Five of the mutations were previously described c.83G>A (p.R28H), c.862C>T (p.R288W), c.904G>A (p.R302G), c.1535T>C (p.L512P), c.700C>T (p.Q234X), while nine novel mutations were identified: four missense c.82C>A (p.R28S), c.494G>A (p.C165Y), c.464G>A (p.C155Y), c.1750G>A (p.G584E), one deletion c.142_144delAGAAGA (p.R48_G50del), and four splice site mutations c.241-2A>G, c.839+4A>G, c.1350-2A>G, c.1566+1G>A. Carrier analysis was performed in 10 mothers and 11 female relatives. The results of this study further support the notion that molecular genetic testing represents an important tool for definitive and early diagnosis of XLA and may allow accurate carrier status and prenatal diagnosis. 相似文献
70.
Ray L. Hanson Alan R. Dahl Simon J. Rothenberg Janet M. Benson Antone L. Brooks John S. Dutcher 《Archives of environmental contamination and toxicology》1985,14(3):289-297
Volatile components from diesel exhaust particles and coal gasifier process gas condensate were vacuum fractionated by cryogenic distillation and identified by infrared spectroscopy and gas chromatography/mass spectrometry. The vacuum distillation line consisted of a sample flask and nine traps cooled from 0°C to ?196°C in approximately 20°C steps. The pressure in the vacuum line of about 10?2 Torr was maintained with a vacuum pump. Separated compounds were identified by comparison to reference infrared spectra and confirmed by comparison with standards when practical. Volatile compounds identified from the diesel exhaust particle sample included NOx, carbon dioxide, sulfur dioxide, alkanes, aldehydes, and one and two ring aromatic hydrocarbons. Volatile compounds identified in process gas condensate from a coal gasifier were ammonia, carbonyl sulfide, carbon dioxide, C3-C7 hydrocarbons, one and two ring aromatic hydrocarbons, and phenols. Volatile components collected at either 0° or ?24°C were evaluated to determine their genotoxicity using the Chinese hamster ovary/hypoxanthine-guanine phosphoribosyltransferase (CHO/HGPRT) assay. Neither the gasifier condensate nor diesel particle samples produced mutations at the HGPRT locus. The diesel samples were not cytotoxic at the concentrations tested (100 μg/ml) but the gasifier samples resulted in 50% cell killing at concentrations between 25 and 100 μg/ml depending on the temperature of collection and the test conditions. Vacuum desorption with cryogenic distillation has provided a means to separate the volatile components in complex environmental samples to allow chemical and biological characterization of these components. 相似文献