全文获取类型
收费全文 | 4390篇 |
免费 | 329篇 |
国内免费 | 128篇 |
专业分类
耳鼻咽喉 | 40篇 |
儿科学 | 81篇 |
妇产科学 | 63篇 |
基础医学 | 538篇 |
口腔科学 | 81篇 |
临床医学 | 449篇 |
内科学 | 764篇 |
皮肤病学 | 83篇 |
神经病学 | 341篇 |
特种医学 | 151篇 |
外科学 | 460篇 |
综合类 | 326篇 |
一般理论 | 1篇 |
预防医学 | 338篇 |
眼科学 | 266篇 |
药学 | 326篇 |
2篇 | |
中国医学 | 46篇 |
肿瘤学 | 491篇 |
出版年
2024年 | 4篇 |
2023年 | 37篇 |
2022年 | 111篇 |
2021年 | 168篇 |
2020年 | 138篇 |
2019年 | 115篇 |
2018年 | 149篇 |
2017年 | 105篇 |
2016年 | 117篇 |
2015年 | 181篇 |
2014年 | 215篇 |
2013年 | 208篇 |
2012年 | 371篇 |
2011年 | 417篇 |
2010年 | 215篇 |
2009年 | 160篇 |
2008年 | 286篇 |
2007年 | 304篇 |
2006年 | 251篇 |
2005年 | 225篇 |
2004年 | 173篇 |
2003年 | 157篇 |
2002年 | 116篇 |
2001年 | 74篇 |
2000年 | 68篇 |
1999年 | 47篇 |
1998年 | 47篇 |
1997年 | 33篇 |
1996年 | 21篇 |
1995年 | 22篇 |
1994年 | 16篇 |
1993年 | 20篇 |
1992年 | 29篇 |
1991年 | 32篇 |
1990年 | 33篇 |
1989年 | 21篇 |
1988年 | 22篇 |
1987年 | 20篇 |
1986年 | 16篇 |
1985年 | 17篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1977年 | 6篇 |
1976年 | 9篇 |
1973年 | 10篇 |
1972年 | 4篇 |
1970年 | 3篇 |
1964年 | 4篇 |
排序方式: 共有4847条查询结果,搜索用时 15 毫秒
21.
Immune inflammation was induced by injecting bovine serum albumin (BSA) into 6-day-old air pouches of mice presensitized with 2 weekly injections of an emulsion containing BSA and complete Freund's adjuvant. Control mice were also similarly pretreated with the same emulsion without BSA. The results show that the numbers of exudate leucocytes in the air pouches of both test and control groups increased and peaked at 4 h and then declined after the antigen challenge. However, the values of exudate leucocytes in the test animals at 4- and 24-hour intervals were significantly lower than those of the control. On the other hand, exudate histamine of the test group peaked at 1 h, and this was significantly higher than that of the control. Injection of exogenous histamine or histaminase with the challenging antigen increased the number of exudate leucocytes in both test and control animals. The findings thus suggest that endogenous histamine released in immune inflammation most probably plays the same role as in non-immune inflammation by enhancing the vascular permeability at the inflammatory site in the early phase of the inflammatory reaction. 相似文献
22.
Changes in the human immunodeficiency virus p7-p1-p6 gag gene in drug-naive and pretreated patients 下载免费PDF全文
Resistance to antiretroviral agents often results from mutations within the human immunodeficiency virus (HIV) pol gene. Moreover, insertions within the p6 gag-pol region have recently been found to be involved with resistance to nucleoside analogs. Overall, we found that 21% of 156 specimens collected from HIV-infected individuals (17.6% from 74 drug-naive patients and 24.4% from 82 pretreated patients) harbored these insertions. Insertions around the KQE (Lys-Gln-Glu) motif were found in 12.2% of the pretreated patients but in none of the drug-naive subjects (P = 0.002). In contrast, insertions around the PTAP (Prol-Thre-Ala-Prol) motif were seen at similar rates ( approximately 15%) among drug-naive and pretreated patients, which supports the idea that they may be natural polymorphisms. 相似文献
23.
Jamet D Marzin Y Douet-Guilbert N Morel F Le Bris MJ Herry A Banzakour S Bourquard P Morice P Abgrall JF Berthou C De Braekeleer M 《Cancer Genetics and Cytogenetics》2005,161(2):159-163
Jumping translocations (JT) have been defined as nonreciprocal translocations involving a same donor chromosome arm or chromosome segment onto two or more recipient chromosomes in different cell lines in the same patient, leading to a mosaic karyotype. This definition has been expanded to also include extra copies of a same donor segment on different recipient chromosomes in a single clone. Six patients with multiple myeloma and JT involving chromosome arm 1q were identified among 37 patients presenting with chromosome 1 abnormalities. All six patients had an advanced disease and a short survival. The literature review allowed us to identify 24 additional patients with JT. Chromosomes 16 and 19 were the recipients in 11 (45.8%) and 6 (25%) of these 24 patients, respectively. Breakpoints on the recipient chromosomes were pericentromeric in 46.2% and telomeric in 40.4% of the breakpoints recorded. Since telomeres are made of (TTAGGG)n tandem DNA repeats that are also found in the pericentromeric heterochromatic regions (interstital telomeric sequences), it is presumed that jumping translocations arise through illegimate recombination between telomere repeat sequences and interstitial telomeric sequences. 相似文献
24.
Angèle S Jones C Reis Filho JS Fulford LG Treilleux I Lakhani SR Hall J 《Journal of clinical pathology》2004,57(11):1179-1184
AIMS: To analyse the expression of proteins involved in DNA double strand break detection and repair in the luminal and myoepithelial compartments of benign breast lesions and malignant breast tumours with myoepithelial differentiation. METHODS: Expression of the ataxia telangiectasia (ATM) and p53 proteins was immunohistochemically evaluated in 18 benign and malignant myoepithelial tumours of the breast. Fifteen benign breast lesions with prominent myoepithelial compartment were also evaluated for these proteins, in addition to those in the MRE11-Rad50-NBS1 (MRN) complex, and the expression profiles were compared with those seen in eight independent non-cancer (normal breast) samples and in the surrounding normal tissues of the benign and malignant tumours examined. RESULTS: ATM expression was higher in the myoepithelial compartment of three of 15 benign breast lesions and lower in the luminal compartment of eight of these lesions compared with that found in the corresponding normal tissue compartments. Malignant myoepithelial tumours overexpressed ATM in one of 18 cases. p53 was consistently negative in benign lesions and was overexpressed in eight of 18 malignant tumours. In benign breast lesions, expression of the MRN complex was significantly more reduced in myoepithelial cells (up to 73%) than in luminal cells (up to 40%) (p=0.0005). CONCLUSIONS: Malignant myoepithelial tumours rarely overexpress ATM but are frequently positive for p53. In benign breast lesions, expression of the MRN complex was more frequently reduced in the myoepithelial than in the luminal epithelial compartment, suggesting different DNA repair capabilities in these two cell types. 相似文献
25.
He Q Manopo I Lu L Leung BP Chng HH Ling AE Chee LL Chan SW Ooi EE Sin YL Ang B Kwang J 《Clinical and diagnostic laboratory immunology》2005,12(2):321-328
Severe acute respiratory syndrome (SARS) is caused by a novel and highly infectious virus named SARS coronavirus (SARS-CoV). Among the serological tests currently available for the detection of SARS-CoV, a whole-virus-based immunofluorescence assay (IFA) was considered one of the most sensitive assays and served as a "gold standard" during the SARS epidemic in Singapore in 2003. However, the need to manipulate live SARS-CoV in the traditional IFA limits its wide application due to the requirement for a biosafety level 3 laboratory and the risk of laboratory infection. Previously, we have identified two immunodominant epitopes, named N195 and Sc, in the two major structural proteins, the N and S proteins, of SARS-CoV (Q. He, K. H. Chong, H. H. Chng, B. Leung, A. E. Ling, T. Wei, S. W. Chan, E. E. Ooi, and J. Kwang, Clin. Diagn. Lab. Immunol., 11:417-422, 2004; L. Lu, I. Manopo, B. P. Leung, H. H. Chng, A. E. Ling, L. L. Chee, E. E. Ooi, S. W. Chan, and J. Kwang, J. Clin. Microbiol. 42:1570-1576, 2004). In the present study, the N195-Sc fusion protein was highly expressed in insect (Sf9) cells infected with a recombinant baculovirus bearing the hybrid gene under the control of a polyhedrin promoter. An IFA based on Sf9 cells producing the fusion protein was standardized with 23 serum samples from patients with SARS, 20 serum samples from patients with autoimmune diseases, and 43 serum samples from healthy blood donors. The detection rates were comparable to those obtained with a commercial SARS-CoV IFA kit (EUROIMMUN, Gross Groenau, Germany) and a conventional IFA performed at the Singapore General Hospital. Our data showed that the newly developed IFA could detect SARS-CoV in 22 of the 23 SARS-CoV-positive serum samples and gave no false-positive results when the sera from patients with autoimmune diseases and healthy individuals were tested. The detection rate was identical to those of the two whole-virus-based IFAs. Thus, the novel N-S fusion antigen-based IFA could be an attractive alternative to present whole-virus-based IFAs for the diagnosis of SARS-CoV infection. 相似文献
26.
27.
This study was designed to determine whether the somatostatin analogue,
octreotide, could prevent embryonic loss by normalizing increased uterine
insulin-like growth factor-I (IGF-I) action related to hyperoestrogenaemia
following superovulation. Superovulated immature and
oestradiol-17beta-treated adult rats were infused with 100 or 300 microg/ml
of octreotide respectively, or injected daily with 1 or 10 microg of
octreotide from day 1 to day 3 of pregnancy. On day 3, embryos were
collected from the oviducts and uteri. Uterine luminal fluid was subjected
to embryo culture. The amounts of uterine IGF-I and IGF binding proteins
(IGFBP) were determined by radioimmunoassay and ligand binding assay
respectively. Octreotide infusion normalized uterine IGF-I action following
superovulatory and oestradiol-17beta treatment, by reducing IGF-I
concentrations and increasing IGFBP concentrations. Octreotide infusion
increased the number of normal embryos by 2.7-fold and 1.7-fold in
superovulated and oestradiol-17beta- treated rats respectively, and
reversed the detrimental effects of uterine luminal fluid on embryonic
development caused by superovulatory and oestradiol-17beta treatment. Daily
injections with octreotide had similar but reduced effects in all
parameters examined in both treatment groups. In conclusion, octreotide may
reduce embryonic loss, at least in part, by normalizing IGF-I action
following superovulation.
相似文献
28.
Trypanosoma evansi (Trypanosomatidae, Kinetoplastida) is a salivarian trypanosomatid that infects eight mammal orders spread over America, Europe and Asia. In Brazil, T. evansi is the etiological agent of Mal de Cadeiras, a horse disease very often described in the region known as Pantanal do Mato Grosso. Few data concerning the genetic diversity and biology of subpopulations of T. evansi that circulate in Brazil are available. The factors that modulate the interaction of this parasite with its hosts also remain to be elucidated. Here we evaluated the course of experimental infection of six T. evansi isolates derived from domestic and wild animals in Swiss-Webster mice and three Mus musculus lineages. The follow-up included biological, immunological as well as biochemical and hematological parameters. The same isolates as well as three others were characterized by pulsed-field electrophoresis. Our results showed that T. evansi isolates displayed significant differences regarding behavior and morbidity patterns in the distinct mouse lineages. Nevertheless, these differences could not be correlated with pulsed-field electrophoresis profiles. Indeed, concerning this molecular marker, only microheterogeneity was observed. Moreover, we observed that the outcome of the infection is defined by both host genetic background and peculiarities (virulence factors) of the distinct T. evansi isolates. Anemia and hypoglycemia were the only features that could be observed in all mouse lineages, independently of the inoculated T. evansi subpopulation. In addition, our data also show that Mus musculus is a suitable model host for the study of the different pathogenetic features of T. evansi infection. 相似文献
29.
Hypoxia can contribute to the induction of the Epstein-Barr virus (EBV) lytic cycle. 总被引:1,自引:0,他引:1
Ju-Hong Jiang Na Wang Ang Li Wen-Ting Liao Zhi-Gang Pan Shi-Juan Mai Da-Jiang Li Mu-Sheng Zeng Jian-Ming Wen Yi-Xin Zeng 《Journal of clinical virology》2006,37(2):98-103
BACKGROUND: Like other herpes viruses, latent Epstein-Barr virus (EBV) infection can be reactivated to lytic replication. Reactivation can be achieved by treatment with various reagents, including tetradecanoyl phorbol acetate (TPA) and Ca2+ ionophores. Relatively little is known about the physiological factors related to reactivation of EBV. Previous studies have demonstrated that G0/G1 cell cycle arrest is associated with EBV activation, and that hypoxic conditions can induce cell cycle arrest. In the present study we investigated the effect of hypoxia on reactivation of EBV. OBJECTIVE AND METHODS: Hypoxic culture conditions were established and the expression of Zta protein and the number of EBV DNA copies were measured in B95-8 cells maintained under these conditions. RESULTS: Hypoxia treatment not only increased the expression of the EBV immediate-early protein Zta (which mediates the switch between the latent and lytic form of infection), but also increased the number of EBV DNA copies in B95-8 cells. CONCLUSIONS: EBV in latent infection can be activated to lytic infection by hypoxia treatment. 相似文献
30.