全文获取类型
收费全文 | 4359篇 |
免费 | 228篇 |
国内免费 | 114篇 |
专业分类
耳鼻咽喉 | 48篇 |
儿科学 | 122篇 |
妇产科学 | 95篇 |
基础医学 | 452篇 |
口腔科学 | 156篇 |
临床医学 | 440篇 |
内科学 | 915篇 |
皮肤病学 | 37篇 |
神经病学 | 439篇 |
特种医学 | 200篇 |
外科学 | 861篇 |
综合类 | 46篇 |
一般理论 | 3篇 |
预防医学 | 179篇 |
眼科学 | 53篇 |
药学 | 312篇 |
中国医学 | 13篇 |
肿瘤学 | 330篇 |
出版年
2023年 | 22篇 |
2022年 | 52篇 |
2021年 | 99篇 |
2020年 | 53篇 |
2019年 | 84篇 |
2018年 | 115篇 |
2017年 | 71篇 |
2016年 | 91篇 |
2015年 | 98篇 |
2014年 | 144篇 |
2013年 | 237篇 |
2012年 | 263篇 |
2011年 | 305篇 |
2010年 | 164篇 |
2009年 | 151篇 |
2008年 | 228篇 |
2007年 | 254篇 |
2006年 | 195篇 |
2005年 | 211篇 |
2004年 | 179篇 |
2003年 | 143篇 |
2002年 | 188篇 |
2001年 | 118篇 |
2000年 | 125篇 |
1999年 | 104篇 |
1998年 | 76篇 |
1997年 | 55篇 |
1996年 | 61篇 |
1995年 | 40篇 |
1994年 | 39篇 |
1993年 | 25篇 |
1992年 | 80篇 |
1991年 | 63篇 |
1990年 | 58篇 |
1989年 | 62篇 |
1988年 | 52篇 |
1987年 | 60篇 |
1986年 | 47篇 |
1985年 | 29篇 |
1984年 | 28篇 |
1983年 | 25篇 |
1982年 | 11篇 |
1981年 | 13篇 |
1980年 | 10篇 |
1979年 | 19篇 |
1973年 | 20篇 |
1971年 | 10篇 |
1970年 | 12篇 |
1969年 | 13篇 |
1965年 | 11篇 |
排序方式: 共有4701条查询结果,搜索用时 11 毫秒
51.
Della Rocca G Pierconti F Vizza CD Pugliese F Coccia C Pompei L Costa MG Venuta F Rendina EA Pietropaoli P Gasparetto A 《Minerva anestesiologica》1999,65(11):785-790
BACKGROUND: The aim of this study is to analyze the effects of dobutamine (DBT) on pulmonary and systemic hemodynamics and oxygenation in lung transplant candidates. METHODS: Forty-five patients (21M, 24F) to be introduced in waiting list for lung transplantation were studied (14 pulmonary fibrosis, 15 COPD, and 16 cystic fibrosis). They were studied awake, while spontaneously breathing in two different phases: baseline--O2 100%; DBT phase--O2 100% after 10 minutes of DBT continuous infusion (10 mcg/Kg/min). Blood gas samples and hemodynamic data were collected during right heart catheterization. Data were statistically analyzed with Student's "t" test and values for p < 0.05 were considered as significant. RESULTS: During DBT phase, a significant increase of cardiac output with a decreasing in systemic and pulmonary vascular resistance was observed. Since the fall in pulmonary vascular resistance (PVRI) was not proportional to the increase of cardiac output, mean pulmonary artery pressure and transpulmonary gradient increased. The prevalent role of vascular recruitment as mechanism in PVRI reduction during DBT is supported by the concomitant fall in PaO2/FiO2. This strongly suggests a worsening of regional Va/Qc due to an increased perfusion of poorly ventilated areas. CONCLUSIONS: DBT reduces PVRI through a recruitment of vessels due to an increase of pulmonary flow. Dobutamine has a favorable hemodynamic effect in mild-to-moderate pulmonary hypertension in lung transplant candidates. 相似文献
52.
F Heidempergher P Pevarello A Pillan V Pinciroli A Della Torre C Speciale M Marconi M Cini S Toma F Greco M Varasi 《Il Farmaco; edizione pratica》1999,54(3):152-160
A series of pyrrolo[3,2-c]quinoline derivatives were synthesised and evaluated as inhibitors of selected enzymes of the kynurenine pathway. 7-Chloro-3-methyl-1H-pyrrolo[3,2-c]quinoline-4-carboxylic acid (7a) was found to be a relatively potent and selective inhibitor of kynurenine-3-hydroxylase (KYN-3-OHase). A molecular modelling study showed a good superimposition of 7a with PNU-156561 and kynurenine the natural substrate of KYN-3-OHase. 相似文献
53.
54.
A Bairati M E Perotti L Vitellaro Zuccarello E Della Morte 《Bulletin de l'Association des anatomistes》1979,63(182):255-262
Ten testicular biopsies from adult males with agenesis of the vas deferens have been investigated with light and electron microscopy. The ultrastructural study of SERTOLI cells has demonstrated that: (a) the junctions between SERTOLI cells and between SERTOLI and germinal cells retain their normal ultrastructural features. (b) Lanthanum permeates SERTOLI cells tight junctions, but its diffusion towards the adluminal compartment is prevented. (c) SERTOLI cells present unusual amounts of cytoplasmic inclusions, especially lipofuscin granules. A relationship between these inclusions and phagocytosis has not been demonstrated. (d) "Dark" SERTOLI cells which show alterations of their typical junctional complex have been frequently observed, although their frequency varies among the different patients. The results are discussed in relation to diagnostic significance of the ultrastructural study of testicular biopsies. 相似文献
55.
56.
Teneriello FL Della Casa U Teneriello GF Alessandrini G Cicchini C Stazi A Ghini C Indinnimeo M 《Il Giornale di chirurgia》2000,21(5):243-247
Annular Pancreas (AP) is a rare congenital anomaly that usually presents in childhood with symptoms referable to duodenal obstruction; nonetheless, this condition can manifest in adulthood with abdominal pain, pancreatitis, duodenal ulcer, pancreatic head mass. The Authors hereby discuss a case of AP observed in a 63 year-old patient in which EUS played a decisive role in achieving a certain diagnosis. 相似文献
57.
Papaloizos MY Le Moine P Prues-Latour V Borisch N Della Santa DR 《The Journal of hand surgery, European volume》2000,25(3):253-257
The clinical and radiological outcomes of 25 surgically treated fractures of the proximal third of the fifth metacarpal were retrospectively analysed. Many different methods of osteosynthesis were used. At follow-up after a mean of 3.3 years, 15 of 25 patients had no pain. Most patients regained a nearly full range of motion in the adjacent joints and more than 90% of the contralateral grip strength. X-ray signs of degenerative arthritis in the metacarpohamate joint were observed in 10 of 25 patients. Pain was found to be directly correlated with the presence of degenerative changes. 相似文献
58.
Donato Gemmati Alessia Ongaro Gian L Scapoli Matteo Della Porta Silvia Tognazzo Maria L Serino Eros Di Bona Francesco Rodeghiero Giuseppe Gilli Roberto Reverberi Angelo Caruso Michela Pasello Agnese Pellati Monica De Mattei 《Cancer epidemiology, biomarkers & prevention》2004,13(5):787-794
Folate and methionine metabolism is involved in DNA synthesis and methylation processes. Polymorphisms in the genes of folate metabolism enzymes have been associated with some forms of cancer. In a case-control study, we evaluated whether four common polymorphisms in methylenetetrahydrofolate reductase (MTHFR C677T and A1298C), methionine synthase (MS A2756G), and methionine synthase reductase (MTRR A66G) genes may have a role in altering susceptibility to adult acute lymphoblastic leukemia (ALL) and non-Hodgkin's lymphoma (NHL). We analyzed DNA of 120 adult ALL, 200 NHL, and 257 healthy control subjects. Individual carrying the MTHFR 677TT genotype showed a 3.6-fold decreased ALL risk [odds ratio (OR) 0.28, 95% confidence interval (95% CI) 0.12-0.72] than wild-types. Similarly, MS 2756GG individuals showed a 5.0-fold decreased ALL risk (OR 0.20, 95% CI 0.02-1.45) than wild-types. In combined results, subjects with the MTHFR 677CT/TT and MS 2756AG/GG genotypes revealed a 3.6-fold ALL risk reduction (OR 0.28, 95% CI 0.14-0.58) and those with the MTHFR 677TT and MTRR 66AG genotypes revealed a 4.2-fold ALL risk reduction (OR 0.24, 95% CI 0.06-0.81). Finally, those with the MS 2756AG/GG and MTRR 66AG/GG genotypes revealed a 2.2-fold ALL risk reduction (OR 0.45, 95% CI 0.10-0.85). Single analysis for NHL did not show any significant difference for all the polymorphisms investigated, but in the low-grade NHL subgroup, we found a 2.0-fold risk reduction for the MTRR 66GG homozygous genotype (OR 0.50, 95% CI 0.25-0.99), which was higher (OR 0.37, 95% CI 0.14-0.85) when analyzed in combination with MS 2756AA genotype. These data are in accordance with the hypothesis that polymorphisms in the genes for folate and methionine metabolism might play a greater role in the occurrence of ALL than NHL by influencing DNA synthesis and/or DNA methylation. 相似文献
59.
hDAF expression in hearts of transgenic pigs obtained by sperm-mediated gene transfer 总被引:5,自引:0,他引:5
60.