全文获取类型
收费全文 | 10858篇 |
免费 | 999篇 |
国内免费 | 16篇 |
专业分类
耳鼻咽喉 | 79篇 |
儿科学 | 252篇 |
妇产科学 | 291篇 |
基础医学 | 1560篇 |
口腔科学 | 298篇 |
临床医学 | 1248篇 |
内科学 | 2546篇 |
皮肤病学 | 86篇 |
神经病学 | 835篇 |
特种医学 | 465篇 |
外科学 | 1283篇 |
综合类 | 187篇 |
一般理论 | 6篇 |
预防医学 | 1313篇 |
眼科学 | 111篇 |
药学 | 753篇 |
中国医学 | 4篇 |
肿瘤学 | 556篇 |
出版年
2021年 | 141篇 |
2020年 | 93篇 |
2019年 | 147篇 |
2018年 | 164篇 |
2017年 | 102篇 |
2016年 | 153篇 |
2015年 | 156篇 |
2014年 | 262篇 |
2013年 | 341篇 |
2012年 | 458篇 |
2011年 | 533篇 |
2010年 | 308篇 |
2009年 | 253篇 |
2008年 | 514篇 |
2007年 | 466篇 |
2006年 | 460篇 |
2005年 | 437篇 |
2004年 | 369篇 |
2003年 | 357篇 |
2002年 | 346篇 |
2001年 | 326篇 |
2000年 | 319篇 |
1999年 | 298篇 |
1998年 | 143篇 |
1997年 | 134篇 |
1996年 | 147篇 |
1995年 | 111篇 |
1994年 | 98篇 |
1993年 | 93篇 |
1992年 | 273篇 |
1991年 | 258篇 |
1990年 | 250篇 |
1989年 | 238篇 |
1988年 | 234篇 |
1987年 | 201篇 |
1986年 | 233篇 |
1985年 | 203篇 |
1984年 | 192篇 |
1983年 | 191篇 |
1982年 | 137篇 |
1981年 | 114篇 |
1980年 | 89篇 |
1979年 | 160篇 |
1978年 | 121篇 |
1977年 | 106篇 |
1976年 | 90篇 |
1974年 | 110篇 |
1973年 | 105篇 |
1972年 | 87篇 |
1968年 | 88篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Detection of chromosomes and estimation of aneuploidy in human spermatozoa using fluorescence in-situ hybridization 总被引:11,自引:0,他引:11
The development and application of fluorescence in-situ hybridization
(FISH) has opened the way for comprehensive studies on numerical chromosome
abnormalities in human spermatozoa. FISH can be rapidly applied to large
numbers of spermatozoa and thus overcomes the major limitation of
karyotyping spermatozoa after penetration of zona-free hamster oocytes. The
simultaneous hybridization of two or more chromosome-specific probes to
spermatozoa and subsequent detection of the bound probes using different
fluorescent detection systems enables two or more chromosomes to be
localized simultaneously in the same spermatozoon and provides a technique
for undertaking reasonable estimates of aneuploidy. The most commonly used
probes are those which bind to the centromeric region of specific
chromosomes. Most studies to date have concentrated on estimating
aneuploidy in spermatozoa from normospermic men, although reports are
beginning to appear on aneuploidy in spermatozoa from subfertile and
infertile men. Multi- probe FISH studies have generally reported disomy
(hyperhaploidy) estimates of 0.05-0.2% per chromosome. There is preliminary
evidence that some chromosomes such as X, Y and 21 are predisposed towards
higher rates of non-disjunction during spermatogenesis. There are also
suggestions of inter-donor variability in aneuploidy frequencies for
specific chromosomes, although this requires confirmation in larger
studies. While FISH is clearly a powerful technique that has many
applications in reproductive medicine, it must also be realized that it
does have limitations and the technology itself is still evolving and has
yet to be fully validated on spermatozoa.
相似文献
82.
Few studies have characterized or compared the pathologic features of bone marrow involvement by extranodal (EMZL), splenic (SMZL), and nodal marginal zone lymphoma (NMZL). We evaluated 45 bone marrow biopsy specimens from 39 patients with marginal zone lymphomas. As previously reported, bone marrow involvement was frequent (100%) in patients with SMZL. We also identified lymphoma involving bone marrow in 11 (44%) of 25 patients with EMZL and 1 of 2 patients with NMZL. The patterns of infiltration were mixed in all groups; however, the extent of involvement was greater in SMZL than in EMZL. In addition, germinal centers were present in bone marrow biopsy specimens involved by lymphoma in 4 patients with SMZL. Intrasinusoidal infiltration was common (10/12 [83%]) and prominent in patients with bone marrow involvement by SMZL, but was not invariably present. Intrasinusoidal infiltration of the bone marrow also was not specific for SMZL since similar infiltrates, although subtle, also were found in patients with other small B-cell lymphoproliferative disorders, including 6 (55%) of 11 patients whose bone marrow samples were infiltrated by EMZL. 相似文献
83.
E G Levine S Juneja D Arthur O M Garson J L Machnicki G Frizzera P Ironside I Cooper D D Hurd B A Peterson 《Genes, chromosomes & cancer》1990,1(4):270-280
The examination of sequential karyotypes in hematologic disorders has demonstrated that karyotypic changes are often associated with concurrent changes in clinical behavior. Acquired abnormalities that recur among different patients may also suggest genomic areas important to tumor progression. We therefore examined sequential karyotypes in 21 patients with non-Hodgkin lymphoma (NHL). Sixteen of the 21 karyotypes demonstrated changes, including the majority of 6 small lymphocytic, 11 follicular, and 4 intermediate and high-grade diffuse lymphomas. The t(14;18)(q32;q21) occurred in ten initial karyotypes was retained in all cases. The band most frequently affected by newly acquired abnormalities was 14q32 (n = 5); chromosomes 1 and 2 (n = 5, each), and the 17p arm (n = 4) were also commonly affected. The acquired deletion of all or part of 17p appeared to be associated with a poor prognosis. Histologic transformation and karyotypic change did not correlate. This study of sequential karyotypes in NHL 1) confirms the primary importance of the t(14;18), 2) suggests that the 14q32 band is involved frequently in both primary and secondary cytogenetic events, and 3) suggests other genomic regions of potential significance to progression. 相似文献
84.
85.
The MMPI was administered twice to 40 graduate students to determine the utility of the Weiner subtle and obvious scales (D, HY, PD, PA, MA) for estimating how fake good and fake bad response sets might influence full scale scores. The first time, the MMPI was administered under standard conditions. Subjects then were divided randomly into two groups: fake good (complete MMPI for job application) and fake bad (qualify for psychotherapy). There were significant multivariate test effects (standard vs. response set) for the raw scores of all five obvious, subtle, and full scales. However, when raw scores were converted to T scores to ascertain practical significance, the obvious scales appeared to provide the most useful information to enhance the interpretation of full scale scores in normal populations. 相似文献
86.
Thomas JA Johnson J Peterson Kraai TL Wilson R Tartaglia N LeRoux J Beischel L McGavran L Hagerman RJ 《American journal of medical genetics. Part A》2003,(2):111-120
The clinical significance of an interstitial duplication of (15)(q11-q13) remains unclear and controversial. The reported phenotypes vary widely and appear to be influenced by the parent of origin of the duplication. Aside from cases of dup(15) reported with autism, the behavioral phenotype of individuals with dup(15) has not been described. We present three families, two with intrachromosomal duplication (15)(q11-q13) ascertained because of developmental delay in a relative. Two families show clear evidence of multigenerational maternal inheritance. The individuals discussed in this paper have minor anomalies and developmental delays. In addition, we describe a behavioral phenotype which often includes attention deficit hyperactivity disorder (ADHD) and autistic spectrum disorder. Responses to medications used to manage these behaviors are also described, including a positive response to methylphenidate and a poor response to fluoxetine. The duplication in each presenting individual, and available family members, was investigated utilizing cytogenetic and molecular techniques including high resolution cytogenetics, fluorescence in situ hybridization (FISH), DNA methylation studies, and quantitative fluorescence PCR. High resolution cytogenetic techniques alone missed some cases, demonstrating the need to confirm results with other methods. 相似文献
87.
C Peterson 《Neuroscience letters》1990,115(2-3):274-278
1,2,3,4-Tetrahydro-5-aminoacridine (THA; tacrine) reportedly improves cognitive deficits in certain individuals with Alzheimer's disease. The present study describes increased glucose oxidation and acetylcholine (ACh) synthesis by mouse brain slices after THA treatment. THA increased [U-14C]glucose decarboxylation and ACh formation in a concentration-dependent manner in hippocampal slices (50 nM less than 50 microM less than microM). In striatal and cortical slices, 50 microM THA effectively elevated the oxidation of glucose and its incorporation into ACh. Thus the efficacy of THA treatment on Alzheimer patients may be partially related to increased ACh synthesis and oxidative metabolism. 相似文献
88.
W J Peterson T Akagawa D G Anderson T Makinodan 《Clinical immunology and immunopathology》1985,35(1):73-84
The radiosensitivity of interleukin-2 (IL-2) production was assessed of (a) peripheral blood mononuclear cells (PBMC) of young humans, dogs, and mice (C57BL/6); (b) PBMC and splenic cells of young mice; and (c) PBMC of young and old humans and the splenic cells of young and old mice. The results indicate that (a) large differences in radiosensitivity exist between the PBMC of humans, dogs, and mice (e.g., the radiation doses which resulted in 37% remaining IL-2 activity (D37) of human, dog, and mouse PBMC were 3771, greater than 10,000, and 1398 rads, respectively); (b) only a small difference exists between the PBMC and splenic cells of mice; and (c) no difference exists between the PBMC of young and old humans and between splenic cells of young and old mice. Topological abnormalities, as judged by scanning electron microscopic analysis, could not be detected in dog PBMC after their exposure to 1800 rads, but could be detected in mouse PBMC after their exposure to 400 rads. 相似文献
89.
Williams LK Peterson EL Pladevall M Tunceli K Ownby DR Johnson CC 《The Journal of allergy and clinical immunology》2005,116(1):102-108
BACKGROUND: Early childhood fevers appear to protect against later allergies and asthma. What is not known is the time in which fevers exert this effect and whether the degree of temperature increase is important. OBJECTIVE: We sought to examine the relationship between the time and degree of early fevers and later allergies and asthma. METHODS: Eight hundred thirty-five children from southeast Michigan were enrolled at birth. Clinic records from their first 2 years were abstracted for episodes of fever. At age 6 to 7 years, children underwent allergy testing. We examined fevers occurring within 6-month intervals in the first 2 years of life and outcomes at age 6 to 7 years. The primary outcome measures were allergic sensitization, asthma, asthma with allergic sensitization, and asthma without allergic sensitization. RESULTS: In the unadjusted analysis each episode of fever between 7 and 12 months of age was associated with a lower odds of allergic sensitization (odds ratio [OR], 0.71; 95% CI, 0.54-0.93) and asthma with allergic sensitization (OR, 0.43; 95% CI, 0.21-0.90) at age 6 to 7 years. Likewise, every 1 degrees C increase in the maximum temperature between 7 and 12 months was associated with a lower odds of allergic sensitization (OR, 0.77; 95% CI, 0.61-0.96) and asthma with allergic sensitization (OR, 0.62; 95% CI, 0.40-0.94). After adjusting for potential confounders, each episode of fever between 7 and 12 months was associated with a lower likelihood of asthma with allergic sensitization (adjusted OR, 0.33; 95% CI, 0.11-0.94) at age 6 to 7 years. CONCLUSIONS: Both the timing and intensity of childhood fevers appear to be important factors in the development of allergies and asthma. 相似文献
90.
Vaughan JR; Farrer MJ; Wszolek ZK; Gasser T; Durr A; Agid Y; Bonifati V; DeMichele G; Volpe G; Lincoln S; Breteler M; Meco G; Brice A; Marsden CD; Hardy J; Wood NW 《Human molecular genetics》1998,7(4):751-753
A mutation in exon 4 of the human alpha-synuclein gene was reported
recently in four families with autosomal dominant Parkinson's disease (PD).
In order to examine whether mutations in this exon or elsewhere in the gene
are common in familial PD, all seven exons of the alpha- synuclein gene
were amplified by PCR from index cases of 30 European and American
Caucasian kindreds affected with autosomal dominant PD. Each product was
sequenced directly and examined for mutations in the open reading frame. No
mutations were found in any of the samples examined. We conclude that the
A53T change described in the alpha- synuclein gene is a rare cause of PD or
may even be a rare variant. Mutations in the regulatory or intronic regions
of the gene were not excluded by this study.
相似文献