全文获取类型
收费全文 | 4471篇 |
免费 | 299篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 81篇 |
儿科学 | 88篇 |
妇产科学 | 88篇 |
基础医学 | 818篇 |
口腔科学 | 218篇 |
临床医学 | 398篇 |
内科学 | 981篇 |
皮肤病学 | 99篇 |
神经病学 | 442篇 |
特种医学 | 66篇 |
外科学 | 336篇 |
综合类 | 12篇 |
一般理论 | 2篇 |
预防医学 | 354篇 |
眼科学 | 86篇 |
药学 | 405篇 |
中国医学 | 14篇 |
肿瘤学 | 304篇 |
出版年
2024年 | 4篇 |
2023年 | 40篇 |
2022年 | 132篇 |
2021年 | 175篇 |
2020年 | 87篇 |
2019年 | 150篇 |
2018年 | 145篇 |
2017年 | 109篇 |
2016年 | 128篇 |
2015年 | 171篇 |
2014年 | 217篇 |
2013年 | 244篇 |
2012年 | 364篇 |
2011年 | 406篇 |
2010年 | 214篇 |
2009年 | 189篇 |
2008年 | 301篇 |
2007年 | 293篇 |
2006年 | 300篇 |
2005年 | 284篇 |
2004年 | 221篇 |
2003年 | 190篇 |
2002年 | 162篇 |
2001年 | 24篇 |
2000年 | 18篇 |
1999年 | 16篇 |
1998年 | 25篇 |
1997年 | 31篇 |
1996年 | 11篇 |
1995年 | 14篇 |
1994年 | 14篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 11篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1980年 | 5篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1970年 | 2篇 |
1969年 | 2篇 |
排序方式: 共有4792条查询结果,搜索用时 15 毫秒
11.
12.
Brian F O'Donnell Marcia A Wilt Ann Marie Hake Julie C Stout Sandra C Kirkwood Tatiana Foroud 《Movement disorders》2003,18(9):1027-1034
Disturbances of visual cognition, visuomotor performance, and visual memory have been described frequently in Huntington's disease (HD). Early stage visual abnormalities could contribute to these deficits. We evaluated visual processing in 20 control subjects who were non-gene carriers at risk for HD, nine presymptomatic gene-positive subjects, and eight subjects with a recent diagnosis of Huntington's disease. Visual perceptual tests of contrast sensitivity and motion discrimination were used to probe early stage visual processing. Extraocular movements were evaluated in a neurologic examination, and the Digit Symbol test was used to test visual motor performance. Contrast sensitivity did not differ among the three groups. Motion discrimination was impaired in HD subjects but not in the presymptomatic gene carriers when compared to gene noncarriers. Among gene carriers, impaired motion discrimination performance was associated with poorer Digit Symbol performance and extraocular abnormalities. These findings suggest that the early stages of HD are associated with disturbances of motion perception as well as disruptions of visual motor and ocular motor performance. 相似文献
13.
14.
Angela Favaro Tatiana Zanetti Elena Tenconi Daniela Degortes Andrea Ronzan Angela Veronese Paolo Santonastaso 《Eating disorders》2004,13(1):61-70
To date, few studies have examined the personality characteristics and clinical predictors of impulsive behaviors in eating disorders (ED). The aim of this work was to study the prevalence of a wide range of impulsive behaviors in a sample of 554 ED subjects and to examine the predictors of these behaviors. Subjects were diagnosed according to DSM-IV criteria as having anorexia nervosa restricting type (ANR; n = 183), anorexia nervosa binge eating/purging type (ANBP; n = 65), bulimia nervosa purging type (BNP; n = 244), and bulimia nervosa nonpurging type (BNNP; n = 62). Nine different types of impulsive behaviors were assessed in these groups. About 55% of the whole sample reported at least one type of impulsive behavior, 35% more than one, and about 13% more than three. According to findings, impulsive and multi-impulsive subjects are characterized by the presence of purging behavior and by specific temperamental features such as high levels of novelty seeking and low persistence. The prediction of impulsive behavior is further improved by considering the presence of a history of childhood abuse, maternal psychiatric morbidity, and some specific psychological symptoms such as maturity fears, perfectionism, depression, and obsessive-compulsive symptoms. The presence of impulsive behavior appears to be associated with overall higher levels of psychiatric symptomatology and eating psychopathology, thus indicating that they are an important feature to be considered in the assessment and treatment of ED. 相似文献
15.
I. N. Nesterova L. M. Alekseeva N. I. Andreeva S. M. Golovina V. G. Granik 《Pharmaceutical Chemistry Journal》1995,29(2):111-114
A simple method of synthesizing derivatives of 5-dimethylaminopyrano[3,2-c]quinolin-2-ones is proposed which involves obttaining 4-chloro- or 4-oxo-3-formylquinolines using compounds having an active methylene group. The pharmacological activity of the synthesized compounds is studied. 相似文献
16.
Vascular endothelial growth factor C is required for sprouting of the first lymphatic vessels from embryonic veins 总被引:3,自引:0,他引:3
Karkkainen MJ Haiko P Sainio K Partanen J Taipale J Petrova TV Jeltsch M Jackson DG Talikka M Rauvala H Betsholtz C Alitalo K 《Nature immunology》2004,5(1):74-80
Lymphatic vessels are essential for immune surveillance, tissue fluid homeostasis and fat absorption. Defects in lymphatic vessel formation or function cause lymphedema. Here we show that the vascular endothelial growth factor C (VEGF-C) is required for the initial steps in lymphatic development. In Vegfc-/- mice, endothelial cells commit to the lymphatic lineage but do not sprout to form lymph vessels. Sprouting was rescued by VEGF-C and VEGF-D but not by VEGF, indicating VEGF receptor 3 specificity. The lack of lymphatic vessels resulted in prenatal death due to fluid accumulation in tissues, and Vegfc+/- mice developed cutaneous lymphatic hypoplasia and lymphedema. Our results indicate that VEGF-C is the paracrine factor essential for lymphangiogenesis, and show that both Vegfc alleles are required for normal lymphatic development. 相似文献
17.
Detection of ethambutol-resistant Mycobacterium tuberculosis strains by multiplex allele-specific PCR assay targeting embB306 mutations 总被引:4,自引:0,他引:4 下载免费PDF全文
Mokrousov I Narvskaya O Limeschenko E Otten T Vyshnevskiy B 《Journal of clinical microbiology》2002,40(5):1617-1620
We describe a multiplex allele-specific (MAS)-PCR assay to detect simultaneously mutations in the first and third bases of the embB gene codon 306ATG. These mutations are known to confer ethambutol (EMB) resistance in the majority of clinical Mycobacterium tuberculosis isolates worldwide. The mutated bases are revealed depending on the presence or absence of the respective indicative fragments amplified from the embB306 wild-type allele. Initially optimized on purified DNA samples, the assay was tested on crude cell lysates and auramine-stained sputum slide DNA preparations with the same reproducibility and interpretability of the generated profiles in agarose gel electrophoresis. Since EMB resistance is generally linked to multiple-drug resistance (MDR), the MAS-PCR assay for EMB resistance detection can be used in clinical laboratory practice in areas with a high prevalence and a high transmission rate of MDR-EMB-resistant tuberculosis. 相似文献
18.
Sputum Cytokine Levels in Patients with Pulmonary Tuberculosis as Early Markers of Mycobacterial Clearance 下载免费PDF全文
Rodrigo Ribeiro-Rodrigues Tatiana Resende Co John L. Johnson Fabiola Ribeiro Moises Palaci Ricardo T. S Ethel L. Maciel Fausto E. Pereira Lima Valderio Dettoni Zahra Toossi W. Henry Boom Reynaldo Dietze Jerrold J. Ellner Christina S. Hirsch 《Clinical and Vaccine Immunology : CVI》2002,9(4):818-823
Sputum and serum from patients with active pulmonary tuberculosis (TB), healthy purified protein derivative-positive adults, and patients with bacterial pneumonia were collected to simultaneously assess local immunity in the lungs and peripheral blood. To determine whether cytokine profiles in sputum from TB patients and control subjects were a reflection of its cellular composition, cytospin slides were prepared in parallel and assessed for the presence of relative proportions of epithelial cells, neutrophils, macrophages, and T cells. Gamma interferon (IFN-γ) in sputum from TB patients was markedly elevated over levels for both control groups. With anti-TB therapy, IFN-γ levels in sputum from TB patients decreased rapidly and by week 4 of treatment were comparable to those in sputum from controls. Further, IFN-γ levels in sputum closely followed mycobacterial clearance. Although detected at fourfold-lower levels, IFN-γ immunoreactivities in serum followed kinetics in sputum. TNF-α, interleukin 8 (IL-8) and IL-6 also were readily detected in sputum from TB patients at baseline and responded to anti-TB therapy. In contrast to IFN-γ, however, TNF-α and IL-8 levels also were elevated in sputum from pneumonia controls. These data indicate that sputum cytokines correlate with disease activity during active TB of the lung and may serve as potential early markers for sputum conversion and response to anti-TB therapy. 相似文献
19.
Xiaoling Xuei Leah Flury-Wetherill Laura Bierut Danielle Dick John Nurnberger Tatiana Foroud Howard J Edenberg 《American journal of medical genetics. Part B, Neuropsychiatric genetics》2007,(7):877-884
Opioid receptors and their endogenous peptide ligands play important roles in neurotransmission and neuromodulation in response to addictive drugs such as heroin, cocaine, and alcohol. In an earlier study, we reported that variation in the genes encoding the kappa-opioid receptor (OPRK1) and its peptide ligand (PDYN) were associated with the risk for alcoholism. We continued our investigation of the role of the opioid system in alcohol dependence by analyzing the genes encoding the micro- and delta-opioid receptors and their peptide ligands. We analyzed 18 OPRM1 SNPs, 18 OPRD1 SNPs, 7 PENK SNPs, and 7 POMC SNPs in a sample of 1923 European Americans from 219 multiplex alcohol dependent families. Employing a family-based test of association, we found no evidence that these four genes were significantly associated with alcohol dependence. We also did not find association between these genes and illicit drug dependence. Secondary analyses employing the narrower phenotype of opioid dependence (83 affected individuals) demonstrated association with SNPs in PENK and POMC, but not in OPRM1 or OPRD1. Haplotype analyses provided further support for the association of PENK and POMC with opioid dependence. Therefore, our data provide no support for the idea that variations in OPRM1, OPRD1, PENK and POMC are associated with alcohol dependence or general illicit drug dependence, but variations in PENK and POMC appear to be associated with the narrower phenotype of opioid dependence in these families. 相似文献
20.
Sulfolipid deficiency does not affect the virulence of Mycobacterium tuberculosis H37Rv in mice and guinea pigs 下载免费PDF全文
Rousseau C Turner OC Rush E Bordat Y Sirakova TD Kolattukudy PE Ritter S Orme IM Gicquel B Jackson M 《Infection and immunity》2003,71(8):4684-4690
Lipids that are found only in the cell envelope of pathogenic mycobacteria, such as those containing multiple methyl-branched fatty acids, have long been thought to play a role in pathogenesis. Among these complex lipids, sulfolipids have been the most extensively studied over the last 50 years. The numerous biological effects exhibited by purified sulfolipids on phagocytic cells led to the idea that these molecules are probably important virulence factors facilitating the intracellular survival of Mycobacterium tuberculosis. However, definitive evidence to support this concept has been lacking. The recent construction of an isogenic sulfolipid-deficient mutant of M. tuberculosis H37Rv (Sirakova et al., J. Biol. Chem. 276:16833-16839, 2001) has for the first time provided the opportunity to directly assess the contribution of these complex lipids to pathogenesis. In the present study, we show that against all expectations, sulfolipid deficiency does not significantly affect the replication, persistence, and pathogenicity of M. tuberculosis H37Rv in mice and guinea pigs or in cultured macrophages. 相似文献