全文获取类型
收费全文 | 23774篇 |
免费 | 1880篇 |
国内免费 | 89篇 |
专业分类
耳鼻咽喉 | 395篇 |
儿科学 | 834篇 |
妇产科学 | 374篇 |
基础医学 | 2423篇 |
口腔科学 | 536篇 |
临床医学 | 2177篇 |
内科学 | 5229篇 |
皮肤病学 | 549篇 |
神经病学 | 1285篇 |
特种医学 | 1141篇 |
外国民族医学 | 1篇 |
外科学 | 4550篇 |
综合类 | 330篇 |
一般理论 | 15篇 |
预防医学 | 1243篇 |
眼科学 | 816篇 |
药学 | 2042篇 |
中国医学 | 38篇 |
肿瘤学 | 1765篇 |
出版年
2023年 | 198篇 |
2022年 | 384篇 |
2021年 | 991篇 |
2020年 | 478篇 |
2019年 | 816篇 |
2018年 | 949篇 |
2017年 | 628篇 |
2016年 | 653篇 |
2015年 | 678篇 |
2014年 | 1020篇 |
2013年 | 1202篇 |
2012年 | 1744篇 |
2011年 | 1717篇 |
2010年 | 877篇 |
2009年 | 824篇 |
2008年 | 1281篇 |
2007年 | 1216篇 |
2006年 | 1129篇 |
2005年 | 982篇 |
2004年 | 886篇 |
2003年 | 751篇 |
2002年 | 647篇 |
2001年 | 593篇 |
2000年 | 550篇 |
1999年 | 494篇 |
1998年 | 168篇 |
1997年 | 147篇 |
1996年 | 149篇 |
1995年 | 154篇 |
1994年 | 128篇 |
1993年 | 103篇 |
1992年 | 273篇 |
1991年 | 286篇 |
1990年 | 249篇 |
1989年 | 219篇 |
1988年 | 214篇 |
1987年 | 225篇 |
1986年 | 196篇 |
1985年 | 179篇 |
1984年 | 116篇 |
1983年 | 130篇 |
1982年 | 89篇 |
1981年 | 71篇 |
1980年 | 60篇 |
1979年 | 130篇 |
1978年 | 78篇 |
1977年 | 70篇 |
1975年 | 59篇 |
1974年 | 65篇 |
1973年 | 88篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
Stenoien DL Cummings CJ Adams HP Mancini MG Patel K DeMartino GN Marcelli M Weigel NL Mancini MA 《Human molecular genetics》1999,8(5):731-741
Spinal bulbar muscular atrophy is a neurodegenerative disorder caused by a polyglutamine expansion in the androgen receptor (AR). We show in transiently transfected HeLa cells that an AR containing 48 glutamines (ARQ48) accumulates in a hormone-dependent manner in both cytoplasmic and nuclear aggregates. Electron microscopy reveals both types of aggregates to have a similar ultrastructure. ARQ48 aggregates sequester mitochondria and steroid receptor coactivator 1 and stain positively for NEDD8, Hsp70, Hsp90 and HDJ-2/HSDJ. Co-expression of HDJ-2/HSDJ significantly represses aggregate formation. ARQ48 aggregates also label with antibodies recognizing the PA700 proteasome caps but not 20S core particles. These results suggest that ARQ48 accumulates due to protein misfolding and a breakdown in proteolytic processing. Furthermore, the homeostatic disturbances associated with aggregate formation may affect normal cell function. 相似文献
142.
Gene expression patterns and gene copy number changes in dermatofibrosarcoma protuberans 总被引:5,自引:0,他引:5 下载免费PDF全文
Linn SC West RB Pollack JR Zhu S Hernandez-Boussard T Nielsen TO Rubin BP Patel R Goldblum JR Siegmund D Botstein D Brown PO Gilks CB van de Rijn M 《The American journal of pathology》2003,163(6):2383-2395
Dermatofibrosarcoma protuberans (DFSP) is an aggressive spindle cell neoplasm. It is associated with the chromosomal translocation, t(17:22), which fuses the COL1A1 and PDGFbeta genes. We determined the characteristic gene expression profile of DFSP and characterized DNA copy number changes in DFSP by array-based comparative genomic hybridization (array CGH). Fresh frozen and formalin-fixed, paraffin-embedded samples of DFSP were analyzed by array CGH (four cases) and DNA microarray analysis of global gene expression (nine cases). The nine DFSPs were readily distinguished from 27 other diverse soft tissue tumors based on their gene expression patterns. Genes characteristically expressed in the DFSPs included PDGF beta and its receptor, PDGFRB, APOD, MEOX1, PLA2R, and PRKCA. Array CGH of DNA extracted either from frozen tumor samples or from paraffin blocks yielded equivalent results. Large areas of chromosomes 17q and 22q, bounded by COL1A1 and PDGF beta, respectively, were amplified in DFSP. Expression of genes in the amplified regions was significantly elevated. Our data shows that: 1) DFSP has a distinctive gene expression profile; 2) array CGH can be applied successfully to frozen or formalin-fixed, paraffin-embedded tumor samples; 3) a characteristic amplification of sequences from chromosomes 17q and 22q, demarcated by the COL1A1 and PDGF beta genes, respectively, was associated with elevated expression of the amplified genes. 相似文献
143.
R Patel G Connor D R Patel A Soriano D Najera 《International archives of allergy and applied immunology》1986,79(2):182-187
Determination of T lymphocyte subsets using monoclonal antibodies revealed a deficiency of suppressor cells and an elevated helper:suppressor T cell ratio in 7 patients with untreated idiopathic immune complex glomerulonephritis and nephrotic syndrome. Possible pathogenetic mechanisms of immunoregulatory cell imbalance and their implications specifically in reference to idiopathic glomerulonephritis are discussed. 相似文献
144.
S C Bell R F James J A Jackson S R Patel G T Waites K Walczak 《American journal of reproductive immunology (New York, N.Y. : 1989)》1989,20(3):87-96
Monoclonal antibodies were raised against pregnancy-associated endometrial alpha 1-globulin (alpha 1-PEG), a 32 KD insulin-like growth factor binding protein (IGF-BP), which represents a major secretory product of the human decidualized endometrium during pregnancy. This class of IGF-BP has been implicated in the modulation of action, inhibitory and stimulatory, of insulin-like growth factors. Immunization with the protein purified from pregnancy endometrium resulted after myeloma fusion in the isolation of six hybridoma clones and the antibodies produced were characterized. The Ka of the antibodies ranged between 4.75 x 10(9) M-1 and 0.7 x 10(8) M-1. In Western blots all monoclonal antibodies reacted with purified protein of molecular weight 32 KD and specifically detected this IGF-BP species in culture medium and cytosolic extracts of pregnancy endometrium and amniotic fluid. The monoclonal antibodies appear to define three epitope-bearing regions as evidenced by their reactivity to polypeptide fragments of the protein. After synthesis and secretion by tissue explants in vitro the protein is susceptible to cleavage into fragments possessing different monoclonal antibody-defined reactivity. Employing immunohistochemical techniques the protein was principally localized to decidual cells in tissue sections of pregnancy endometrium and solely to these cells after enzymic digestion of the tissue. The implications of these results are discussed with respect to potential role of IGF-BP in the action of IGF upon the IGF-1 receptor-bearing populations, including lymphocytes and trophoblast cells, D in the decidua. 相似文献
145.
Mansy HA Hoxie SJ Patel NH Sandler RH 《Medical & biological engineering & computing》2005,43(1):56-62
Vascular access for renal dialysis is a lifeline for about 120 000 individuals in the United States. Stethoscope auscultation
of vascular sounds has some utility in the assessment of access patency, yet can be highly skill-dependent. The objective
of the study was to identify acoustic parameters that are related to changes in vascular access patency. The underlying hypothesis
is that stenoses of haemodialysis access vessels or grafts cause vascular sound changes that are detectable using computerised
data acquisition and analysis. Eleven patients participated in the study. Their vascular sounds were recorded before and after
angiography, which was accompanied by angioplasty in most patients. The sounds were acquired using two electronic stethoscopes
and then digitised and analysed on a personal computer. Vessel stenosis changes were found to be associated with changes in
acoustic amplitude and/or spectral energy distribution. Certain acoustic parameters correlated well (correlation coefficient=0.98,
p<0.0001) with the change in the degree of stenosis, suggesting that stenosis severity may be predictable from these parameters.
Parameters also appeared to be sensitive to modest diameter changes (>20%), (p<0.005, Wilcoxon rank sum test). These results
suggest that computerised analysis of vascular sounds may be useful in vessel patency surveillance. Further testing using
longitudinal studies may be warranted. 相似文献
146.
Antineuron specific enolase staining reactions in sarcomas and carcinomas: its lack of neuroendocrine specificity. 总被引:2,自引:1,他引:2 下载免费PDF全文
A commercially available polyclonal antiserum (Dakopatts) raised against bovine neuron specific enolase (NSE) was reacted with 197 sarcomas, 32 carcinomas, 11 carcinoid tumours and 20 malignant melanomas to assess its specificity for neuroendocrine tumours. All the tumours had been fixed in formalin and embedded in paraffin. Positive tumour cells were found in two of 11 squamous cell carcinomas, one of 11 adenocarcinomas, 10 of 10 oat cell carcinomas, 11 of 11 carcinoid tumours, 16 of 20 malignant melanomas, four of seven clear cell sarcomas, nine of 25 leiomyosarcomas, four of 22 rhabdomyosarcomas, one of seven angiosarcomas and one of 20 synovial sarcomas. 相似文献
147.
H H Goebel W Zeman V K Patel R K Pullarkat H G Lenard 《Mechanisms of ageing and development》1979,10(1-2):53-70
In 4 patients with neuronal ceroid-lipofuscinoses (NCL) (3 patients with the junvenile type, 1 patient with the late infantile type), the ultrastructural spectrum of residual bodies in the central and peripheral nervous system presented curvilinear profiles in all cases and regions investigated and many more ultrastructural patterns within and beyond regions commonly accessible to biopsy, probably due to age dependence, local tissue and cellular biochemical factors. Sampling from basal ganglia especially yielded combined curvilinear-fingerpint bodies, from peripheral ganglia additional membranous bodies. Residual bodies in NCL were present in almost every cell type, similar to the distribution of regular lipofuscin. Although the classical subgroups of NCL contain electronmicroscopically well defined residual bodies, permitting distinction of the late infantile type from the juvenile type, the ultrastructural differences are more of a quantitative than of a qualitative nature. However, they are not pathognomonic. N.m.r. spectra of ceroid and lipofuscin support the concept of their biochemical similarity, and argue against the proposition that they contain a single major component. 相似文献
148.
Campo-Ruiz V Patel D Anderson RR Delgado-Baeza E González S 《International journal of experimental pathology》2005,86(5):297-307
Knee cartilage biopsy is used to confirm the pathology in both clinical and experimental conditions and often guides diagnosis and therapeutic strategies. Current histopathological techniques are time consuming, induce tissue artefacts and often prevent further evaluation, once the tissue has been fixed. Hence, there is a potential need for a fast and nondestructive imaging technique for unfixed tissue. Near-infrared, reflectance confocal microscopy (CM) allows real-time, virtual sectioning of unstained, bulk tissue samples. This pilot study evaluates the use of CM in the assessment of meniscus histopathology in a series of 26 freshly-excised human meniscus samples compared to standard light microscopy of stained sections. CM images of the meniscus show cell and matrix detail, depicting morphologic features of collagen and elastic fibres, vessels and nerve endings. In addition, crystal deposits of gout and pseudogout are also demonstrable. Thus, CM is a novel imaging technique that could enable the pathologist to make a rapid microscopic evaluation of cartilage in a fresh and unfixed fashion. 相似文献
149.
New strategies for prevention and therapy of cytomegalovirus infection and disease in solid-organ transplant recipients 总被引:23,自引:0,他引:23 下载免费PDF全文
In the past three decades since the inception of human organ transplantation, cytomegalovirus (CMV) has gained increasing clinical import because it is a common pathogen in the immunocompromised transplant recipient. Patients may suffer from severe manifestations of this infection along with the threat of potential fatality. Additionally, the dynamic evolution of immunosuppressive and antiviral agents has brought forth changes in the natural history of CMV infection and disease. Transplant physicians now face the daunting task of recognizing and managing the changing spectrum of CMV infection and its consequences in the organ recipient. For the microbiology laboratory, the emphasis has been geared toward the development of more sophisticated detection assays, including methods to detect emerging antiviral resistance. The discovery of novel antiviral chemotherapy is an important theme of clinical research. Investigations have also focused on preventative measures for CMV disease in the solid-organ transplant population. In all, while much has been achieved in the overall management of CMV infection, the current understanding of CMV pathogenesis and therapy still leaves much to be learned before success can be claimed. 相似文献
150.
Sequence variation in the envelope E1 and E2 glycoproteins of hepatitis C virus (HCV) could account for differences in disease pathogenesis in patients infected with different genotypes. A cDNA encoding the structural region of the hepatitis C polyprotein was constructed to match the majority sequence of viral RNA extracted from a patient infected with genotype 3a (designated strain HCV3a-Gla). The principal differences predicted between E2 of HCV3a-Gla and the corresponding H77c genotype 1a protein were that the former contained six more amino acids (361 vs. 355), but it had one fewer glycosylation site. Expression studies showed that, in common with the H77c glycoproteins, E1 and E2 from HCV3a-Gla localised to the endoplasmic reticulum (ER) membrane in both Huh-7 and BHK tissue culture cells and interacted to form native complexes. Analysis of the cross-reactivity of antibodies raised against glycoproteins of genotype 1a strains showed that three of five monoclonal antibodies that recognise linear epitopes were able to detect E2 from strain HCV3a-Gla. However, neither conformational E2 antibodies nor antibodies raised against E1 were able to detect the HCV3a-Gla glycoproteins. In receptor binding assays, E2 of HCV3a-Gla consistently failed to bind CD81, a putative cell receptor for HCV. Absence of binding to CD81 and lack of recognition by most antibodies raised to genotype 1a glycoproteins indicate important differences between these glycoproteins representative of genotypes 3a and 1a. These may be pertinent to the differences in response to interferon therapy and the prevalence of steatosis reported in patients infected with these genotypes. 相似文献