全文获取类型
收费全文 | 19262篇 |
免费 | 1172篇 |
国内免费 | 138篇 |
专业分类
耳鼻咽喉 | 161篇 |
儿科学 | 425篇 |
妇产科学 | 358篇 |
基础医学 | 2232篇 |
口腔科学 | 737篇 |
临床医学 | 1841篇 |
内科学 | 4187篇 |
皮肤病学 | 401篇 |
神经病学 | 1224篇 |
特种医学 | 464篇 |
外国民族医学 | 5篇 |
外科学 | 2500篇 |
综合类 | 486篇 |
一般理论 | 14篇 |
预防医学 | 1571篇 |
眼科学 | 749篇 |
药学 | 1854篇 |
中国医学 | 213篇 |
肿瘤学 | 1150篇 |
出版年
2024年 | 30篇 |
2023年 | 253篇 |
2022年 | 698篇 |
2021年 | 1110篇 |
2020年 | 717篇 |
2019年 | 868篇 |
2018年 | 1030篇 |
2017年 | 724篇 |
2016年 | 808篇 |
2015年 | 808篇 |
2014年 | 1069篇 |
2013年 | 1232篇 |
2012年 | 1696篇 |
2011年 | 1728篇 |
2010年 | 1023篇 |
2009年 | 777篇 |
2008年 | 1138篇 |
2007年 | 1008篇 |
2006年 | 862篇 |
2005年 | 735篇 |
2004年 | 581篇 |
2003年 | 485篇 |
2002年 | 419篇 |
2001年 | 72篇 |
2000年 | 72篇 |
1999年 | 71篇 |
1998年 | 54篇 |
1997年 | 52篇 |
1996年 | 46篇 |
1995年 | 39篇 |
1994年 | 18篇 |
1993年 | 36篇 |
1992年 | 31篇 |
1991年 | 19篇 |
1990年 | 22篇 |
1989年 | 21篇 |
1988年 | 19篇 |
1987年 | 12篇 |
1986年 | 13篇 |
1985年 | 13篇 |
1984年 | 19篇 |
1983年 | 17篇 |
1982年 | 17篇 |
1981年 | 11篇 |
1980年 | 13篇 |
1979年 | 13篇 |
1978年 | 11篇 |
1976年 | 10篇 |
1974年 | 8篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 25 毫秒
21.
Mohammad Hassanzadeh Hassan Gilanpour Saied Charkhkar Johan Buyse Eddy Decuypere 《Avian pathology》2005,34(3):188-193
The present study was designed to compare the anatomical parameters of the cardiopulmonary system in three different lines of chickens with different susceptibility to ascites syndrome. Eggs from three different genetic lines-commercial broiler and layer lines and one native to Iran--were incubated and hatched, and 1-day-old chicks used. The relative heart and lung weights, the volumes of the heart, lung and thorax cavity, the incidence of ascites, and the related physiological parameters in these chickens were followed. Lung weight as a percentage of body weight, the relative lung and heart volume, and the volumes of the thorax cavity, before and after removing heart and lung tissues, were lower in fast-growing broiler chickens compared with the layer and native chickens. Additionally, most of these parameters (e.g. relative lung weight, lung volume and thorax cavity) were significantly decreased with age in broiler chickens but were increased in layer and native chickens, which was concomitant with the incidence of ascites in broiler chickens. Our data indicate that all cardiopulmonary parameters investigated are extremely unfavourable to broiler chickens and suggest a reduction in gas exchange area in broilers, and therefore higher susceptibility to pulmonary hypertension and ascites. 相似文献
22.
Ansar M Din MA Arshad M Sohail M Faiyaz-Ul-Haque M Haque S Ahmad W Leal SM 《European journal of human genetics : EJHG》2003,11(1):77-80
Autosomal recessive nonsyndromic deafness is one of the most frequent forms of inherited hearing impairment. Over 30 autosomal recessive nonsyndromic hearing loss loci have been mapped, and 15 genes have been isolated. Of the over 30 reported autosomal recessive nonsyndromic hearing loss (NSHL) loci, the typical phenotype is prelingual non-progressive severe to profound hearing loss with the exception of DFNB8, which displays postlingual onset and DFNB13, which is progressive. In this report we describe a large inbred kindred from a remote area of Pakistan, comprising six generations and segregating autosomal recessive nonsyndromic prelingual deafness. DNA samples from 24 individuals were used for genome wide screen and fine mapping. Linkage analysis indicates that in this family the NSHL locus, (DFNB35) maps to a 17.54 cM region on chromosome 14 flanked by markers D14S57 and D14S59. Examination of haplotypes reveals a region that is homozygous for 11.75 cM spanning between markers D14S588 and D14S59. A maximum two-point LOD score of 5.3 and multipoint LOD score of 7.6 was obtained at marker D14S53. The interval for DFNB35 does not overlap with the regions for DFNA9, DFNA23 or DFNB5. 相似文献
23.
Somers KL Royals MA Carstea ED Rafi MA Wenger DA Thrall MA 《Molecular genetics and metabolism》2003,79(2):99-103
Niemann-Pick C (NPC) disease is an autosomal recessive neurovisceral lysosomal storage disorder that results in defective intracellular transport of cholesterol. The major form of human NPC (NPC1) has been mapped to chromosome 18, the NPC1 gene (NPC1) has been sequenced and several mutations have been identified in NPC1 patients. A feline model of NPC has been characterized and is phenotypically, morphologically, and biochemically similar to human NPC1. Complementation studies using cultured fibroblasts from NPC affected cats and NPC1 affected humans support that the gene responsible for the NPC phenotype in this colony of cats is orthologous to human NPC1. Using human-based PCR primers, initial fragments of the feline NPC cDNA were amplified and sequenced. From these sequences, feline-specific PCR primers were generated and designed to amplify six overlapping bands that span the entire feline NPC1 open reading frame. A single base substitution (2864G-C) was identified in NPC1 affected cats. Obligate carriers are heterozygous at the same allele and a PCR-based assay was developed to identify the geneotype of all cats in the colony. The mutation results in an amino acid change from cysteine to serine (C955S). Several of the mutations identified in people occur in the same region. Marked similarity exists between the human and feline NPC1 cDNA sequences, and is greater than that between the human and murine NPC1 sequences. The human cDNA sequence predicts a 1278aa protein with a lysosomal targeting sequence, several trans-membrane domains and extensive homology with other known mediators of cholesterol homeostasis. 相似文献
24.
Coprological examination of 40 Apodemus mystacinus Danford and Alston 1877 from Jordan revealed oocysts of three species of genus Eimeria. Two species are described as new. Eimeria zuhairamri sp. n. has broadly ellipsoidal oocysts 29.6 (27.0–34.0)×23.3 (22.0–25.0) m with distinctly granulated wall and oocyst residuum. Endogenous development occurs in jejunum and ileum. Eimeria alorani sp. n. has oocysts 26.9 (23.0–29.0)×19.3 (18.0–22.0) m with smooth wall and absent residuum. Endogenous development is confined to the caecum. The third species, developing in jejunum, has oocysts morphologically indistinguishable from Eimeria uptoni. The identity of E. uptoni and the taxonomy of Eimeria of Apodemus are discussed. 相似文献
25.
S Kageyama O Yamada S S Mohammad S Hama N Hattori M Asanaka E Nakayama T Matsumoto F Higuchi T Kawatani 《Journal of virological methods》1988,22(2-3):125-131
The measurement of HIV antigen levels in sera or plasma of HIV-infected individuals is critical for determining the existence of antigen or infectious virus before seroconversion and for prognosis. Pretreatment of sera or plasma of HIV carriers by heating at 70 degrees C for 10 min at an acidic pH enabled us to estimate antigens efficiently in immune complexes. This procedure will also be useful in determining antigen levels in HIV carriers more precisely. 相似文献
26.
27.
Sharafi M 《International journal of medical sciences》2005,2(2):79-86
Many neuroimaging studies of schizophrenia have shown abnormalities in the frontal cortex, limbic system, basal ganglia, temporal and parietal lobes. These findings are not specific or consistent enough to build up a coherent theory of the origin of the brain abnormality in schizophrenia. This paper describes a state-of-the-art approach of SPECT to correlate neuropsychological evaluation. PANSS scores and different brain focal abnormalities of two groups of patients receiving Clozapine and classical antipsychotic treatments were observed. A total of 20 drug-free patients, actively psychotic schizophrenic, were selected according to the DSM-IV criteria. Pre-Post-treatment was designed using PANSS and 99mTc- ECD-SPECT to assess regional Cerebral Blood Flow (rCBF). The results showed that after treatment, differences in PANSS scores were significant in both groups, with superior scores resulting from the Clozapine therapy. Results were supported by SPECT, which showed a greater improvement in the Clozapine group. Both positive and negative symptoms were improved with Clozapine as well. Before treatment, hypofrontality was the most common (85%) finding, whereas after treatment hypofrontality was mostly cleared. However, in some areas like temporal and caudate, hyperfrontality was induced. Negative symptoms showed linkage to hypofrontality in both groups before and after treatment, and both positive and negative symptoms were improved more with Clozapine therapy than with classical treatment. 相似文献
28.
In the event of smallpox bioterrorism, widespread vaccination may be required. Vaccinia immune globulin (VIG) has been used to treat complications from the smallpox vaccine. While the potency of VIG was defined by its ability to neutralize intracellular mature virus, a second form of vaccinia called the extracellular enveloped virus (EEV) is critical for virus spread in the host. The B5R-protein is one of many EEV-specific proteins. Immunoprecipitation and ELISA revealed that VIG recognizes the B5R-protein. An EEV plaque-reduction assay using a recombinant vaccinia that lacks the majority of the extracellular domain of B5R showed that the ability of VIG to neutralize EEV is principally directed at B5R. In addition, absorbing out the anti-B5R antibody present in VIG through the addition of recombinant B5R protein abrogated VIG's ability to significantly neutralize wild-type EEV. This work demonstrates the prominent role of B5R as a target of EEV-neutralizing activity of human antibodies. 相似文献
29.
Mohammad Sotoudeh Shila Jalali Shunichi Usami John Y-J. Shyy Shu Chien 《Annals of biomedical engineering》1998,26(2):181-189
The objective of this study is to design a new apparatus to allow the control of the magnitude and frequency of dynamic stretch applied uniformly to cells cultured on a silicon elastic membrane. The apparatus is designed to produce equi-biaxial dynamic stretches with area changes ranging from 0% to 55% and frequencies ranging from 0 to 2 Hz. Homogeneous finite strain analysis using triangles of markers was performed to compute the symmetric two-dimensional Lagrangian strain tensor on the membrane. Measurements of strain in both static and dynamic conditions showed that the shear component of the strain tensor (Erc) was near zero, and that there was no significant difference between radial (Err) and circumferential (Ecc) components, indicating the attainment of equi-biaxial strain. Bovine aortic endothelial cells were transiently transfected with a chimeric construct in which the luciferase reporter is driven by TPA-responsive elements (TRE). The transfected cells cultured on the membrane were stretched. The luciferase activity increased significantly only when the cells were stretched by 15% or more in area. Cells in different locations of the membrane showed similar induction of luciferase activities, confirming that strain is uniform and equi-biaxial across the membrane. © 1998 Biomedical Engineering Society.
PAC98: 8780+s, 8745-k, 8722-q 相似文献
30.
The role of COX-2 in angiogenesis and rheumatoid arthritis 总被引:4,自引:0,他引:4
Woods JM Mogollon A Amin MA Martinez RJ Koch AE 《Experimental and molecular pathology》2003,74(3):282-290
Recent evidence suggests that cyclooxygenase (COX)-2 is a mediator of angiogenesis, and COX-2 activity is known to be upregulated in the rheumatoid arthritis (RA) synovium. We examined whether mediation of angiogenesis by COX-2 was occuring in cells of the RA synovium and in microvascular endothelial cells (ECs) that are similar to those found in the RA synovium. We demonstrate that rofecoxib, a selective COX-2 inhibitor, acts directly on human dermal microvascular ECs (HMVECs) to inhibit their chemotactic and tube forming ability. Likewise, pretreatment of HMVECs with rofecoxib significantly inhibited their ability to form tubes induced by conditioned media (CM) of activated RA synovial fibroblasts. When RA synovial fibroblasts were pretreated with rofecoxib for 16 h and then stimulated with interleukin (IL)-1beta, their CM induced significantly less HMVEC tube formation when compared with CM from vehicle-treated RA synovial fibroblasts. ELISAs performed on activated RA fibroblast CM for known proangiogenic factors demonstrated a significant reduction in bFGF, in addition to the expected decrease in PGE(2). Our studies suggest that COX-2-induced angiogenic activity is an active mechanism within diseased synovium and may provide an additional rationale for the use of COX-2 inhibitors in RA. 相似文献