全文获取类型
收费全文 | 12873篇 |
免费 | 693篇 |
国内免费 | 75篇 |
专业分类
耳鼻咽喉 | 167篇 |
儿科学 | 287篇 |
妇产科学 | 234篇 |
基础医学 | 1858篇 |
口腔科学 | 1293篇 |
临床医学 | 910篇 |
内科学 | 2687篇 |
皮肤病学 | 310篇 |
神经病学 | 908篇 |
特种医学 | 218篇 |
外科学 | 1321篇 |
综合类 | 52篇 |
一般理论 | 4篇 |
预防医学 | 1493篇 |
眼科学 | 238篇 |
药学 | 1049篇 |
中国医学 | 123篇 |
肿瘤学 | 489篇 |
出版年
2023年 | 125篇 |
2022年 | 297篇 |
2021年 | 518篇 |
2020年 | 328篇 |
2019年 | 427篇 |
2018年 | 539篇 |
2017年 | 341篇 |
2016年 | 387篇 |
2015年 | 413篇 |
2014年 | 606篇 |
2013年 | 659篇 |
2012年 | 1045篇 |
2011年 | 1189篇 |
2010年 | 662篇 |
2009年 | 462篇 |
2008年 | 793篇 |
2007年 | 766篇 |
2006年 | 610篇 |
2005年 | 580篇 |
2004年 | 519篇 |
2003年 | 430篇 |
2002年 | 394篇 |
2001年 | 213篇 |
2000年 | 208篇 |
1999年 | 166篇 |
1998年 | 54篇 |
1997年 | 37篇 |
1996年 | 33篇 |
1995年 | 32篇 |
1994年 | 25篇 |
1993年 | 24篇 |
1992年 | 80篇 |
1991年 | 65篇 |
1990年 | 56篇 |
1989年 | 57篇 |
1988年 | 40篇 |
1987年 | 33篇 |
1986年 | 38篇 |
1985年 | 36篇 |
1984年 | 20篇 |
1983年 | 19篇 |
1979年 | 23篇 |
1978年 | 18篇 |
1977年 | 18篇 |
1974年 | 18篇 |
1973年 | 24篇 |
1972年 | 15篇 |
1970年 | 17篇 |
1969年 | 23篇 |
1967年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
Mazzanti L Cicognani A Baldazzi L Bergamaschi R Scarano E Strocchi S Nicoletti A Mencarelli F Pittalis M Forabosco A Cacciari E 《American journal of medical genetics. Part A》2005,135(2):150-154
The identification of Y-chromosome material is important in females with Ullrich-Turner syndrome (UTS) due to the risk of developing gonadoblastoma or other gonadal tumors. There is controversy regarding the frequency of the Y-chromosome-derived material and the occurrence of gonadoblastoma in these patients. The aim of our study was to evaluate a large number of patients with UTS, followed before and during the pubertal age for the prevalence of Y-chromosome derived material, the occurrence of gonadoblastoma, and the incidence of possible neoplastic degeneration. An unselected series of 171 patients with UTS (1-34 years old), diagnosed cytogenetically, was studied for Y-chromosome markers (SRY and Y-centromeric DYZ3 repeats). The follow-up was of 2-22 years; 101 of these patients were followed during pubertal age. Y-chromosome material was found in 14 patients (8%): 12 of these were gonadectomized (2.8-25.9 years). A gonadoblastoma was detected in four patients under 16 years of age: in two, Y-material was detected only at molecular analysis (at conventional cytogenetic analysis, one was included in the 45,X group and one in the X + mar group) and one had also an immature teratoma and an endodermal sinus carcinoma. The prevalence of gonadoblastoma in our series of gonadectomized UTS patients with Y-positive material was of 33.3% (4/12). Our data suggest that the age of appearance and the possibility of malignant degeneration of gonadoblastoma can occur early in life. These patients, in particular those with 45,X or a marker chromosome may benefit from molecular screening to detect the presence of Y-chromosome material; PCR is a rapid and inexpensive technique. At the moment, laparoscopy and preventive gonadectomy performed as soon as possible remain the procedures of choice for patients with UTS, when Y-chromosome has been identified, as we are still unable to predict a future malignant evolution of gonadoblastoma. 相似文献
53.
Establishing phenotypic features associated with morbidity in human T-cell lymphotropic virus type 1 infection 总被引:1,自引:0,他引:1
Brito-Melo GE Souza JG Barbosa-Stancioli EF Carneiro-Proietti AB Catalan-Soares B Ribas JG Thorum GW Rocha RD Martins-Filho OA;Grupo Interdisciplinar de Pesquisas em HTLV 《Clinical and diagnostic laboratory immunology》2004,11(6):1105-1110
The human T-cell lymphotropic virus type 1 (HTLV-1) is the causative agent of HTLV-1-associated myelopathy/tropical spastic paraparesis (HT). Although it is widely believed that virus infection and host immune response are involved in the pathogenic mechanisms, the role of the immune system in the development and/or maintenance of HT remains unknown. We performed an analysis of the peripheral blood leukocyte phenotype for two different subcohorts of HTLV-1-infected individuals to verify the existence of similar immunological alterations, possible laboratory markers for HT. The leukocyte population balance, the activation status of the T lymphocytes, and the cellular migratory potential of T lymphocytes, monocytes, and neutrophils were evaluated in the peripheral blood of HTLV-1-infected individuals classified as asymptomatic individuals, oligosymptomatic individuals, and individuals with HT. Data analysis demonstrated that a decreased percentage of B cells, resulting in an increased T cell/B cell ratio and an increase in the CD8+ HLA-DR+ T lymphocytes, exclusively in the HT group could be identified in both subcohorts, suggesting its possible use as a potential immunological marker for HT for use in the laboratory. Moreover, analysis of likelihood ratios showed that if an HTLV-1-infected individual demonstrated B-cell percentages lower than 7.0%, a T cell/B cell ratio higher than 11, or a percentage of CD8+ HLA-DR+ T lymphocytes higher than 70.0%, this individual would have, respectively, a 12-, 13-, or 22-times-greater chance of belonging to the HT group. Based on these data, we propose that the T cell/B cell ratios and percentages of circulating B cells and activated CD8+ T lymphocytes in HTLV-1-infected patients are important immunological indicators which could help clinicians monitor HTLV-1 infection and differentiate the HT group from the asymptomatic and oligosymptomatic groups. 相似文献
54.
dos Santos CN Rocha CF Cordeiro M Fragoso SP Rey F Deubel V Desprès P 《Virus research》2002,90(1-2):197-205
We have investigated the genetic diversity of dengue type-1 (DEN-1) virus in Brazil. The full nucleotide sequences of three DEN-1 virus isolated from DEN fever (DF) and DEN hemorrhagic fever patients in northeastern Brazil in 1997 (BR/97) and one from a DF patient in the south of Brazil in 2001 (BR/01) were compared to that of the reference strain BR/90 obtained in the city of Rio de Janeiro in 1990. Sequence analysis showed that the structural proteins were remarkably conserved between all isolates. A total of 27 amino acid changes occurred throughout the non-structural proteins. Among them, nine amino acid substitutions were specific of BR/97 and BR/01 isolates, indicating that in situ evolution of these strains had occurred. Within the BR/97 and BR/01 samples, some amino acid substitutions have been previously identified in DEN-1 virus strains sequenced so far, suggesting that recombination events might have occurred. 相似文献
55.
Partitioning of whey proteins, bovine serum albumin and porcine insulin in aqueous two-phase systems 总被引:1,自引:0,他引:1
Alves JG Chumpitaz LD da Silva LH Franco TT Meirelles AJ 《Journal of chromatography. B, Biomedical sciences and applications》2000,743(1-2):235-239
Partitioning of the proteins from cheese whey, bovine serum albumin and porcine insulin were analysed using aqueous two-phase systems (ATPS) prepared with PEG-phosphate, PEG-citrate and PEG-maltodextrin (MD). Proteins were quantified through one of the following methods: FPLC, Bradford and spectrophotometry at 280 nm. Results showed that whey proteins partitioned unevenly on the phases of the systems used, with alpha-lactoalbumin (alpha-La) concentrated in the upper phase and beta-lactoglobulin (beta-Lg) in the lower. Albumin in PEG-MD systems concentrated in the MD-rich lower phase. Porcine insulin showed great affinity with the PEG-rich phase, its partition coefficient was always over 10 and increases with PEG molecular mass. 相似文献
56.
57.
Development and evaluation of a rapid dipstick assay for serodiagnosis of acute human brucellosis 下载免费PDF全文
Smits HL Basahi MA Díaz R Marrodan T Douglas JT Rocha A Veerman J Zheludkov MM Witte OW de Jong J Gussenhoven GC Goris MG van Der Hoorn MA 《Journal of clinical microbiology》1999,37(12):4179-4182
A dipstick assay for the detection of brucella-specific immunoglobulin M antibodies was evaluated with 707 sera from 247 laboratory-confirmed brucellosis patients and 342 control sera from brucellosis-free individuals. These sera were collected from six different countries. The assay was found to be highly sensitive and specific. In addition, the test is easy to use and does not require specialized training or equipment, and the components are stable without a requirement for refrigeration. All of these factors make the test ideal for developing countries and rural settings. 相似文献
58.
Nomura M Akama KT Alves SE Korach KS Gustafsson JA Pfaff DW Ogawa S 《Neuroscience》2005,130(2):445-456
We examined the distribution of estrogen receptor (ER)-alpha and ER-beta immunoreactive (ir) cells in the dorsal (DRN) and median/paramedian (MPRN) raphe nuclei in male mice. ER-alpha ir neurons were scattered across the three subdivisions (ventral, dorsal, and lateral) of the DRN and the MPRN. Robust ER-beta ir cells were observed throughout the raphe nuclei, and were particularly abundant in the ventral and dorsal subdivisions of the DRN. Using dual-label immunocytochemistry for ER-alpha or ER-beta with tryptophan hydroxylase (TPH), the rate-limiting enzyme for 5-hydroxytryptamine (5-HT) synthesis, over 90% of ER-beta ir cells exhibited TPH-ir in all DRN subdivisions, whereas only 23% of ER-alpha ir cells contained TPH. Comparisons of ER-alpha knockout (alphaERKO) as well as ER-beta knockout (betaERKO) mice with their respective wild-type (WT) littermates revealed that gene disruption of either ER-alpha or ER-beta did not affect the other ER subtype expression in the raphe nuclei. In situ hybridization histochemistry revealed that there was a small but statistically significant decrease in TPH mRNA expression in the ventral DRN subdivision in betaERKO mice compared with betaWT mice, whereas TPH mRNA levels were not affected in alphaERKO mice. These findings support a hypothesis that ER-beta activation may contribute to the estrogenic regulation of neuroendocrine and behavioral functions, in part, by acting directly on 5-HT neurons in the raphe nuclei in male mice. 相似文献
59.
A satellite DNA has been cloned from the neotropical primateCallithrix argentata and designated CarB. The presence of the satellite was assayed in New and Old World primates by blot hybridization: CarB is highly amplified in the genomes of all three species belonging to theC. argentata species group (C. argentata, C. emiliae, C. humeralifer), but is either absent, or present in only minor amounts, in other primates, including the closely related species,C. jacchus. A completely sequenced CarB monomeric unit was 1528 bp in length and mapped to the telomeric C-band-positive regions of manyC. argentata species group chromosomes. Sequence data from eight CarB clones indicated an average difference of 3.5% when base substitutions alone were counted. The hybridization and sequence data suggest that this satellite underwent a period of amplification and dispersal in the genome of a recent ancestor of theC. argentata species group. 相似文献
60.
Rocha V Wagner JE Sobocinski KA Klein JP Zhang MJ Horowitz MM Gluckman E 《The New England journal of medicine》2000,342(25):1846-1854
BACKGROUND: Umbilical-cord blood as an alternative to bone marrow for hematopoietic stem-cell transplantation may lower the risk of graft-versus-host disease (GVHD). METHODS: We studied the records of 113 recipients of cord blood from HLA-identical siblings from the period from 1990 through 1997 and compared them with the records of 2052 recipients of bone marrow from HLA-identical siblings during the same period. The study population consisted of children 15 years of age or younger. We compared the rates of GVHD, hematopoietic recovery, and survival using Cox proportional-hazards regression to adjust for potentially confounding factors. RESULTS: Recipients of cord blood were younger than recipients of bone marrow (median age, 5 years vs. 8 years; P<0.001), weighed less (median weight, 17 kg vs. 26 kg; P<0.001), and were less likely to have received methotrexate for prophylaxis against GVHD (28 percent vs. 65 percent, P<0.001). Multivariate analysis demonstrated a lower risk of acute GVHD (relative risk, 0.41; P=0.001) and chronic GVHD (relative risk, 0.35; P=0.02) among recipients of cord-blood transplants. As compared with recovery after bone marrow transplantation, the likelihood of recovery of the neutrophil count and the platelet count was significantly lower in the first month after cord-blood transplantation (relative risk, 0.40 [P<0.001], and relative risk, 0.20 [P<0.001]), respectively. Mortality was similar in the two groups (relative risk of death in the recipients of cord blood, 1.15; P=0.43). CONCLUSIONS: Recipients of cord-blood transplants from HLA-identical siblings have a lower incidence of acute and chronic GVHD than recipients of bone marrow transplants from HLA-identical siblings. 相似文献