全文获取类型
收费全文 | 6577篇 |
免费 | 490篇 |
国内免费 | 24篇 |
专业分类
耳鼻咽喉 | 82篇 |
儿科学 | 149篇 |
妇产科学 | 100篇 |
基础医学 | 943篇 |
口腔科学 | 164篇 |
临床医学 | 638篇 |
内科学 | 1551篇 |
皮肤病学 | 85篇 |
神经病学 | 657篇 |
特种医学 | 261篇 |
外科学 | 1023篇 |
综合类 | 59篇 |
一般理论 | 5篇 |
预防医学 | 366篇 |
眼科学 | 131篇 |
药学 | 334篇 |
中国医学 | 8篇 |
肿瘤学 | 535篇 |
出版年
2023年 | 60篇 |
2022年 | 101篇 |
2021年 | 187篇 |
2020年 | 134篇 |
2019年 | 167篇 |
2018年 | 199篇 |
2017年 | 148篇 |
2016年 | 163篇 |
2015年 | 197篇 |
2014年 | 264篇 |
2013年 | 330篇 |
2012年 | 524篇 |
2011年 | 503篇 |
2010年 | 325篇 |
2009年 | 259篇 |
2008年 | 467篇 |
2007年 | 445篇 |
2006年 | 391篇 |
2005年 | 384篇 |
2004年 | 314篇 |
2003年 | 308篇 |
2002年 | 268篇 |
2001年 | 56篇 |
2000年 | 40篇 |
1999年 | 55篇 |
1998年 | 49篇 |
1997年 | 37篇 |
1996年 | 40篇 |
1995年 | 45篇 |
1994年 | 30篇 |
1993年 | 41篇 |
1992年 | 32篇 |
1991年 | 32篇 |
1990年 | 29篇 |
1989年 | 32篇 |
1988年 | 39篇 |
1987年 | 34篇 |
1986年 | 25篇 |
1985年 | 22篇 |
1984年 | 28篇 |
1983年 | 27篇 |
1982年 | 28篇 |
1981年 | 26篇 |
1980年 | 13篇 |
1979年 | 21篇 |
1978年 | 16篇 |
1975年 | 12篇 |
1974年 | 17篇 |
1973年 | 13篇 |
1972年 | 13篇 |
排序方式: 共有7091条查询结果,搜索用时 15 毫秒
41.
Prior electrical stimulation of the medial prefrontal cortex MFC facilitated the subsequent acquisition of intracranial self-stimulation (ICSS) from the same MFC electrode site. Stimulations that were spaced over a period of six days were more effective in producing this facilitation than the same number of stimulations delivered over a two day period. These data suggest that the rewarding effects of MFC stimulation may involve some process akin to the kindling phenomenon and as such may provide insights in the neuronal modifications thought to underlie learning and memory. 相似文献
42.
Thierry Janssen MD Michel Petein MD Roland van Velthoven MD Patrick van Leer MD Marc Fourmarier MD Juan-Pablo Vanegas MD Andre Danguy PhD Claude Schulman MD Jean-Lambert Pasteels MD Robert Kiss PhD 《Human pathology》1996,27(12):1341-1347
The histochemical binding pattern of the peanut (Arachis hypogaea) lectin (PNA) was quantitatively described by means of computer-assisted microscope analysis in 28 benign prostatic hyperplasias (BPH), 15 prostatic intraepithelial neoplasias (PIN), and 119 prostatic adenocarcinomas. PNA exhibits noninunune but selective binding to glycoproteins with β-D-galactosyl(1,3)-N-acetyl-D-galactosamine residues. We also investigated whether a relationship existed between the number of histochemical-related PNA acceptors and the histochemical prostate-specific antigen (PSA) stain intensity, and between the number of PNA receptors and DNA ploidy level. The results show that neoplastic prostate tissues and high-grade intraepithelial prostatic neoplasias (PIN2_3) exhibit a significantly higher number of PNA acceptors than benign prostatic hyperplasias and low (PIN1) grade prostatic intraepithelial neoplasias. A statistically significant correlation was observed between the number of histochemically related PNA acceptors and PSA immunostain intensity. Lastly, diploid prostatic tumors, whether benign or malignant, exhibited a significantly higher number of PNA acceptors than aneuploid ones. These results suggest that PNA acceptors play an important role in the biology of prostate tumors. 相似文献
43.
Bilateral salpingectomy does not compromise ovarian stimulation in an in-vitro fertilization/embryo transfer programme 总被引:9,自引:5,他引:9
Verhulst Guy; Vandersteen Nadia; Van Steirteghem Andre C.; Devroey Paul 《Human reproduction (Oxford, England)》1994,9(4):624-628
The question whether salpingectomy has a negative influenceon ovarian function and the outcome of pregnancy in an in-vitrofertilization (IVF) and embryo transfer treatment programmeis not yet answered. We performed a retrospective case-controlstudy to investigate the possible negative effect of salpingectomyon ovarian response to human menopausal gonadotrophins (HMG)during IVF and embryo transfer. The study group was composedof 26 patients with bilateral salpingectomy. In 67 cycles weanalysed different parameters of ovulation such as the numberof days of ovarian stimulation, numbers of ampoules of HMG,pre-ovulatory oestradiol concentrations and the numbers of oocytesretrieved. These parameters were compared to a control groupof 134 cycles in 134 women with healthy Fallopian tubes. Nodifferences were found. Implantation ratio, pregnancy rate andoutcome were the same in both groups. We conclude that bilateralsalpingectomy had no detrimental effect on ovarian performanceduring IVF and embryo transfer treatment nor on the outcome. 相似文献
44.
Rajendra Prasad Philippe De Wergifosse Andre Goffeau Elisabetta Balzi 《Current genetics》1995,27(4):320-329
By functional complementation of a PDR5 null mutant of Saccharomyces cervisiae, we have cloned and sequenced the multidrug-resistance gene CDR1 of Candida albicans. Transformation by CDR1 of a PDR5-disrupted host hypersensitive to cycloheximide and chloramphenicol resulted in resistance to cycloheximide, chloramphenicol and other drugs, such as the antifungal miconazole, with collateral hypersensitivity to oligomycin, nystatin and 2,4 dinitrophenol. Our results also demonstrate the presence of several PDR5 complementing genes in C. albicans, displaying multidrug-resistance patterns different from PDR5 and CDR1. The nucleotide sequence of CDR1 revealed that, like PDR5, it encodes a putative membrane pump belonging to the ABC (ATP-binding cassette) superfamily. CDR1 encodes a 1501-residue protein of 169.9 kDa whose predicted structural organization is characterized by two homologous halves, each comprising a hydrophobic region with a set of six transmembrane stretches, preceded by a hydrophilic nucleotide binding fold. 相似文献
45.
Philippe Rondou Marcel Van Beylen Celest Samyn Gert S'Heeren Andre Persoons 《Macromolecular chemistry and physics.》1992,193(12):3045-3055
The synthesis and second harmonic coeficients d33, d 31 and the susceptibilities χ(2) are reported of three series of (co)polymethacrylates that possess 4-(2,2-dicyanovinyl)- or 4-(2-cyano-2-methoxycarbonyl)vinyl-N,N-dialkylaniline (P1 and P2), 4-(2,2-dicyanovinyl)- or 4-(2-cyano-2-methoxycarbonyl)vinyl-(-piperidino)benzene (P5 and P6) and 4-(2,2-dicyano)- or 4-(2-cyano-2-methoxycarbonyl)vinyl-1-alkoxybenzene (P3 and P4) dyes 1 System. names of the monomers see Exptl. part. . The second-order nonlinear optical properties of corona-poled aligned polymer films were evaluated by second harmonic generation measurements. The χ values for the P1 and P2 polymers vary from 58 to 318, respectively 32 to 106 · 10?9 esu, for P3 and P4 from 7,6 to 19, respectively 4,4 to 7,4 · 10 ?9 esu and for P5 and P6 from 219 to 42,8 respectively 28,1 to 8,1 · 10?9 esu, depending on the dye chromophore concentration incorporated in the polymer structure. 相似文献
46.
TRIO amplification and abundant mRNA expression is associated with invasive tumor growth and rapid tumor cell proliferation in urinary bladder cancer
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Zheng M Simon R Mirlacher M Maurer R Gasser T Forster T Diener PA Mihatsch MJ Sauter G Schraml P 《The American journal of pathology》2004,165(1):63-69
Studies by comparative genome hybridization have suggested that 5p amplification is related to tumor progression in urinary bladder cancer. In this study seven genes (TAS2R, ADCY2, DNAH5, CTNND2, TRIO, ANKH, and MYO10) located to 5p15.31-5p15.1 were analyzed by fluorescence in situ hybridization using a tissue microarray containing samples from tumors and cell lines with known 5p amplification by comparative genome hybridization. Amplification frequency was highest for TRIO, which maps to 5p15.2 and encodes a protein with a putative role in cell-cycle regulation. To further investigate the role of TRIO amplification in bladder cancer, a tissue microarray containing samples from 2317 bladder tumors was used for fluorescence in situ hybridization analysis. TRIO amplification was strongly associated with invasive tumor phenotype, high tumor grade, and rapid tumor cell proliferation (Ki67 LI) (P < 0.0001 each). Only 7 of 456 pTaG1/G2 tumors (1.5%) but 62 of 485 pT1-4 carcinomas (12.8%) had TRIO amplification. TRIO amplification was not associated with poor prognosis. Using a frozen bladder tumor tissue microarray RNA in situ hybridization confirmed that TRIO is up-regulated in amplified tumors. It is concluded that TRIO up-regulation through amplification has a potential role in bladder cancer progression. 相似文献
47.
48.
49.
Dr. Eric Delcourt Philippe Franken Andre Lenaers 《European journal of nuclear medicine and molecular imaging》1985,11(4):123-126
When performing equilibrium radionuclide angiocardiography with two successive acquisition views, absolute left-ventricular volumes can be calculated using an internal standard generated by a computer in the left-ventricular cavity. The method is based on the computed ratio of maximum to global activity in the 40°-left-anterior-oblique view after background correction and on the measured depth of the left ventricle in almost-orthogonal, 30°-left-posterior-oblique Fourier first-harmonic images. The method does not require blood sampling or correction for self attenuation. The intra- and interobserver reproducibility is excellent, even in patients with severe impairment of the ventricular-contractility pattern. When compared with a classical method requiring venous-blood counting and an attenuation correction factor, the accuracy of the internalstandard method was fairly good, with a regression coefficient of 0.90. 相似文献
50.
Francisca de Castro Mendes Kirstie Ducharme-Smith Gustavo Mora-Garcia Saleh A. Alqahtani Maria Stephany Ruiz-Diaz Andre Moreira Rodrigo Villegas Vanessa Garcia-Larsen 《Nutrients》2021,13(6)
Increasing epidemiological evidence suggests that optimal diet quality helps to improve preservation of lung function and to reduce chronic obstructive pulmonary disease (COPD) risk, but no study has investigated the association of food insecurity (FI) and lung health in the general population. Using data from a representative sample of US adults who participated in the National Health and Nutrition Examination Survey (NHANES) 2007–2012 cycles, we investigated the association between FI with lung function and spirometrically defined COPD in 12,469 individuals aged ≥ 18 years of age. FI (high vs. low) was defined using the US Department of Agriculture’s Food Security Scale). Population-weighted adjusted regression models were used to investigate associations between FI, and forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), their ratio, and spirometrically defined restriction (FVC below the lower limit of normal) and airflow obstruction (COPD). The prevalence of household FI was 13.2%. High household FI was associated with lower FVC (adjusted β-coefficient −70.9 mL, 95% CI −116.6, −25.3), and with higher odds (OR) of spirometric restriction (1.02, 95% CI 1.00, 1.03). Stratified analyses showed similar effect sizes within specific ethnic groups. High FI was associated with worse lung health in a nationally representative sample of adults in the US. 相似文献