全文获取类型
收费全文 | 11837篇 |
免费 | 785篇 |
国内免费 | 23篇 |
专业分类
耳鼻咽喉 | 75篇 |
儿科学 | 418篇 |
妇产科学 | 232篇 |
基础医学 | 1382篇 |
口腔科学 | 156篇 |
临床医学 | 1296篇 |
内科学 | 1996篇 |
皮肤病学 | 148篇 |
神经病学 | 1546篇 |
特种医学 | 546篇 |
外科学 | 2016篇 |
综合类 | 122篇 |
一般理论 | 22篇 |
预防医学 | 1138篇 |
眼科学 | 108篇 |
药学 | 823篇 |
中国医学 | 24篇 |
肿瘤学 | 597篇 |
出版年
2023年 | 62篇 |
2022年 | 90篇 |
2021年 | 245篇 |
2020年 | 163篇 |
2019年 | 271篇 |
2018年 | 309篇 |
2017年 | 209篇 |
2016年 | 252篇 |
2015年 | 240篇 |
2014年 | 427篇 |
2013年 | 588篇 |
2012年 | 903篇 |
2011年 | 954篇 |
2010年 | 528篇 |
2009年 | 485篇 |
2008年 | 831篇 |
2007年 | 797篇 |
2006年 | 782篇 |
2005年 | 825篇 |
2004年 | 752篇 |
2003年 | 716篇 |
2002年 | 651篇 |
2001年 | 101篇 |
2000年 | 67篇 |
1999年 | 89篇 |
1998年 | 140篇 |
1997年 | 102篇 |
1996年 | 104篇 |
1995年 | 90篇 |
1994年 | 71篇 |
1993年 | 54篇 |
1992年 | 58篇 |
1991年 | 45篇 |
1990年 | 33篇 |
1989年 | 39篇 |
1988年 | 57篇 |
1987年 | 40篇 |
1986年 | 36篇 |
1985年 | 29篇 |
1984年 | 44篇 |
1983年 | 45篇 |
1982年 | 47篇 |
1981年 | 33篇 |
1980年 | 48篇 |
1979年 | 26篇 |
1978年 | 20篇 |
1977年 | 19篇 |
1976年 | 21篇 |
1972年 | 14篇 |
1971年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
101.
Varicocele--the most common cause of male factor infertility? 总被引:5,自引:0,他引:5
Varicocele is often cited as the most common cause of male factor infertility. Arguments in support of this statement include reports of increased prevalence of varicocele in populations of infertile men compared with fertile or otherwise unselected men, association of varicocele with abnormal semen parameters, and improvements in semen parameters and/or pregnancy rates after varicocele repair. Logically, there would appear to be three possibilities regarding the relationship between varicocele and fertility: (i) varicocele has no association with or effect on male fertility; (ii) varicocele may be associated with, but is not the cause of, male subfertility; and (iii) varicocele is a direct cause of male subfertility. In the following, we review evidence from the literature for and against these three possibilities: at the current time, available evidence appears inadequate to confirm or deny any of these three possibilities. Since the ultimate goal of infertile couples is to conceive, it seem logical that future varicocele research should focus primarily on adequately powered, controlled clinical trials in well-characterized infertile couples, randomized to intervention or appropriate controlled observation, with pregnancy as the primary outcome. 相似文献
102.
103.
Alan W Johnson Sandra J Potthoff Leslie Carranza Heather M Swenson Christine R Platt Jon R Rathbun 《Academic medicine》2006,81(3):252-256
The authors describe the development and impact of CLARION, a student-run organization at the University of Minnesota founded in 2001 and dedicated to furthering interprofessional education for health professions students. CLARION's student founders recognized that three recent reports from the Institute of Medicine will fuel significant changes in health professions education. Moreover, they deduced that targeted, interprofessional education in the preclinical years could provide fundamental skills and understanding needed to make today's patient care safer and more effective. By engaging health care professionals and faculty, CLARION creates and conducts extracurricular, interprofessional experiences for students that are reflective of the six IOM aims for health care. Student members are from four separate schools of the university's academic health center: medicine, nursing, pharmacy, and public health. The organization's capstone event, the Interprofessional Case Competition, challenges interprofessional teams of students to compete in conducting and presenting a root cause analysis of a fictitious sentinel event. The interprofessional organizational structure of the CLARION board models the kind of interprofessional equality needed to effectively solve problems in the health care system. The interaction among students from different health professions has led them to many new understandings about health care and the realization that many fundamental biases about other professions are firmly rooted in students before they enter the workplace. CLARION has enabled continued professional development of students, faculty, and practitioners, leading individual students to enhanced understanding of the health care system. It is a grassroots catalyst that has prompted faculty to reexamine traditional health professions curricula and look for ways to integrate more interprofessional opportunities into it. 相似文献
104.
Hoshino Y Honma S Jones RW Ross J Santos N Gentsch JR Kapikian AZ Hesse RA 《Virology》2005,332(1):177-188
Of five globally important VP7 (G) serotypes (G1-4 and 9) of group A rotaviruses (the single most important etiologic agents of infantile diarrhea worldwide), G9 continues to attract considerable attention because of its unique natural history. Serotype G9 rotavirus was isolated from a child with diarrhea first in the United States in 1983 and subsequently in Japan in 1985. Curiously, soon after their detection, G9 rotaviruses were not detected for about a decade in both countries and then reemerged in both countries in the mid-1990s. Unexpectedly, however, such reemerged G9 strains were distinct genetically and molecularly from those isolated in the 1980s. Thus, the origin of the reemerged G9 viruses remains an enigma. Sequence analysis has demonstrated that the G9 rotavirus VP7 gene belongs to one of at least three phylogenetic lineages: lineage 1 (strains isolated in the 1980s in the United States and Japan), lineage 2 (strains first isolated in 1986 and exclusively in India thus far), and lineage 3 (strains that emerged/reemerged in the mid-1990s). Currently, lineage 3 G9 viruses are the most frequently detected G9 strains globally. We characterized a porcine rotavirus (A2 strain) isolated in the United States that was known to belong to the P[7] genotype but had not been serotyped by neutralization. The A2 strain was found to bear serotype G9 and P9 specificities as well as NSP4 [B] and subgroup I characteristics. By VP7-specific neutralization, the porcine G9 strain was more closely related to lineage 3 viruses than to lineage 1 or 2 viruses. Furthermore, by sequence analysis, the A2 VP7 was shown to belong to lineage 3 G9. These findings raise intriguing questions regarding possible explanations for the emergence of variations among the G9 strains. 相似文献
105.
Data are presented on the family distribution of nearsightedness, including the frequency of the disorder in the children of two myopes. The previous literature is reviewed, embracing several quantitative family or population studies in addition to extensive pedigree material. It is concluded that there is substantial evidence that recessive inheritance is the principal mechanism of transmission, and that most instances of myopia probably fall into that category. 相似文献
106.
Tim Martin Mark A McDaniel Melissa J Guynn Jon M Houck C Chad Woodruff Joel Pearson Bish Sandra N Moses Dubravko Kici? Claudia D Tesche 《International journal of psychophysiology》2007,64(3):247-258
We measured brain activity using magnetoencephalography in five participants during ongoing tasks that included prospective memory, retrospective memory, and oddball trials. Sources were identified in the hippocampal formation and posterior parietal and frontal lobes. Posterior parietal cortex activation had an earlier onset in the prospective memory condition than retrospective memory or oddball conditions, a higher level of theta activity in the retrospective condition, and higher levels of upper alpha in the prospective and oddball conditions. Activation of the hippocampal formation had a longer duration in the retrospective memory and prospective memory conditions than the oddball condition, but prominent alpha and theta band activity was present in all three conditions. We interpret the early (87 ms) onset of activity in parietal cortex as evidence for an initial noticing of appropriate conditions for a PM response. Hippocampal activity may reflect a subsequent memory search for the intended action. 相似文献
107.
J. Mark Ebertz Jeanne M. Hermens J. Clifford McMillan Hideo Uno Carol Hirshman Jon M. Hanifin 《Inflammation research》1986,18(5-6):455-462
Intravenous administration of morphine sulfate often produces urticarial and hypotensive reactions associated with elevations in plasma histamine. The source of this histamine and mechanisms controlling its release are poorly understood. Previous studies of morphine-induced histamine release compared human leukocytes to rat peritoneal mast cells. The effects of morphine on human cutaneous mast cells has not been examined. We studiedin vitro histamine release from human basophils and human skin preparations containing cutaneous mast cells to evaluate their relative, contribution to the pharmacologic effects of morphine.Human skin mast cell preparations showed dosedependent histamine release over a morphine concentration range of 1.5×10–5 to 4.5×10–3
M, with peak release occurring at 5×10–4
M, with peak release occurring at 5×10–4
M. Clinically, morphine sulfate is usually injected as a 1.5×10–2
M solution. Histamine release was calcium dependent and equivalent to that obtained with 3 and 10 mM strontium. Morphologic examination revealed degranulation and exocytosis occurring in morphine-stimulated tissue but not in specimens exposed to buffer alone. Lactate dehydrogenase levels did not increase following morphine incubation, thus supporting a noncytolytic mechanism of histamine release.Basophils, in contrast, showed no significant histamine release from exposure to morphine up to 10–2
M. Concanavalin A, as a positive control in these same preparations, produced a mean histamine release of 21.0%.Our studies indicate distinct functional differences between human skin mast cell and human blood basophil responses to morphine sulfate. We conclude that the cutaneous and systemic reactions to morphine sulfate probably result from the release of histamine from mast cells rather than from basophils.This study was supported by: National Institutes of Health Grants 2-T32 AMO7153, 5-RO1 AI18615, AI 15557, HL 25831, American Society of Anesthesiologists Starter Grant 1283, and a grant from the Bramble Foundation. 相似文献
108.
Nigel A. Cunliffe Bimal K. Das Madhumati Ramachandran Maharaj K. Bhan Roger I. Glass Jon R. Gentsch 《Virus genes》1997,15(1):39-44
We have sequenced the genes encoding the inner capsid protein VP6 and the nonstructural proteins NSP1 and NSP4 of the Indian
neonatal serotype P8[11]G9 human/bovine reassortant candidate vaccine rotavirus strain 116E. These three genes share a high
degree of sequence and deduced amino acid homology with human prototype strain Wa. Our results confirm and extend those of
previous RNA-RNA hybridization studies which suggested that these genes are of human origin, and will facilitate examination
of the host immune response to 116E induced by natural infection and vaccination.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
109.
Proctopexy using synthetic mesh is a popular method of treating rectal prolapse. Suturing the graft to the presacral fascia is time-consuming and can lead to complications. With the fascial staper®, two parallel rows of three staples are used to quickly and securely anchor the Marlex sling to the sacrum, thus avoiding hemorrhage from the presacral veins. Fourteen patients have been treated with no complications. 相似文献
110.
Jon Årtun Stig K. Osterberg Donald R. Joondeph 《Journal of clinical periodontology》1986,13(9):856-861
Periodontal status was studied at the mesiobuccal, midbuccal and distobuccal aspects of contralateral pairs of canines in 22 postorthodontic patients aged 30 to 51 years with a mean time of 26.4 years (SD, 5.6) out of active treatment. The pretreatment models showed one canine erupting severely to the labial ("ectopic") with a contralateral canine in good arch alignment (control). None of the patients experienced relapse of the "ectopic" canine in a labial direction, and none had missing teeth, malalignment, overhanging restorations or open tooth contacts adjacent to the canines evaluated. Periodontal parameters were examined using a Michigan #0 probe with Williams markings. A nonstandardized light force was used and the measurements were rounded to the nearest millimeter. The results demonstrated statistically significant differences between the canines in probing attachment and bone levels (mean, 0.75; SD, 0.92; P less than 0.01) and width of attached gingiva (mean, 0.50; SD, 1.07; p less than 0.05) at the midbuccal aspects. The reason for these differences could only be speculated upon. 相似文献