全文获取类型
收费全文 | 989篇 |
免费 | 46篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 25篇 |
妇产科学 | 17篇 |
基础医学 | 91篇 |
口腔科学 | 57篇 |
临床医学 | 73篇 |
内科学 | 344篇 |
皮肤病学 | 10篇 |
神经病学 | 61篇 |
特种医学 | 69篇 |
外科学 | 143篇 |
综合类 | 4篇 |
预防医学 | 29篇 |
眼科学 | 19篇 |
药学 | 30篇 |
肿瘤学 | 60篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 20篇 |
2021年 | 38篇 |
2020年 | 24篇 |
2019年 | 29篇 |
2018年 | 31篇 |
2017年 | 15篇 |
2016年 | 35篇 |
2015年 | 22篇 |
2014年 | 45篇 |
2013年 | 47篇 |
2012年 | 90篇 |
2011年 | 98篇 |
2010年 | 53篇 |
2009年 | 44篇 |
2008年 | 78篇 |
2007年 | 73篇 |
2006年 | 78篇 |
2005年 | 55篇 |
2004年 | 40篇 |
2003年 | 29篇 |
2002年 | 24篇 |
2001年 | 4篇 |
2000年 | 10篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1962年 | 1篇 |
1960年 | 1篇 |
1940年 | 2篇 |
排序方式: 共有1044条查询结果,搜索用时 31 毫秒
1.
2.
Leptin and adiponectin represent two newly discovered adipose tissue derived hormones with important roles in energy homeostasis and insulin resistance. Their interrelations with the manifestations of the HIV associated metabolic syndrome and specific somatomorphic changes i.e. fat redistribution is reviewed. A synopsis of published studies is presented and the potential role of leptin and adiponectin is discussed. We have described an association of the HIV metabolic syndrome with a state of reduced insulin sensitivity due to adiponectin deficiency. The metabolic syndrome is also accompanied by leptin deficiency in lipoatrophic subjects and possibly by a leptin resistance state in lipohypertrophic patients. Adiponectin and / or leptin therapy in a manner similar to other leptin deficiency states may assist in the future management of such patients. 相似文献
3.
Objectives: The investigation of the effect of time and type of menopause on bone mineral density (BMD) at different ages. Methods: Five hundred and fourteen women, who had never received any hormonal substitution were studied in a cross-sectional design: 177 with normal (NMP), 210 with surgical (SUMP) and 127 with premature natural (EMP) menopause. Age at menopause was 49.1±3.9, 38.3±4.7 and 38.1±4.2 years (mean±1 S.D.), respectively. BMD was measured at L2–L4 vertebrae and proximal femur by the DEXA method. Results: EMP women presented significantly lower vertebral BMD than NMP women in the 45–55-years segments (P<0.001), but did not differ from SUMP women. This group exhibited lower vertebral BMD than NMP between 45 and 50 years (P<0.001). Regarding femoral neck, EMP women exhibited lower values than SUMP in the 45–50 and 55–65 age segments (P<0.001) whereas SUMP women presented significantly higher BMD values than NMP women after 55 years of age (P<0.001). The percentages of women with vertebral BMD (T-score values) in the osteoporotic range were significantly greater in EMP compared with either NMP or SUMP groups (both P<0.001) whereas in femoral neck lower in SUMP than the other two categories. Conclusions: Women with either natural or surgical premature menopause exhibit lower BMD of trabecular bone compared with normal menopause women at the age segments 45–55 and 45–50, respectively. However, surgical menopause women exceed normal menopause women in their mixed bone BMD values after 60 years as well as premature natural menopause women at almost all age segments. 相似文献
4.
Detection of genetic alterations in primary bladder carcinoma with dual-color and multiplex fluorescence in situ hybridization 总被引:4,自引:0,他引:4
Stamouli MI Panani AD Ferti AD Petraki C Oliver RT Raptis SA Young BD 《Cancer Genetics and Cytogenetics》2004,149(2):107-113
Cytogenetic studies of bladder cancer have shown several nonrandom aberrations. Numerical aberrations of both sex chromosomes were investigated in 32 primary bladder tumors with bicolor fluorescence in situ hybridization (FISH). Loss of chromosome Y and overrepresentation of chromosome X were observed in subgroups of male patients. Chromosome X was represented normally in female patients. Two of the above primary bladder tumors, a transitional cell carcinoma (TCC) and an adenocarcinoma, were further analyzed with both multiplex FISH (24-color M-FISH) and G-banding. Both cases exhibited 1) common breakpoints on 5q11 approximately q12 and 15q24; 2) involvement of the pericentromeric area of chromosome 13; 3) structural abnormalities of chromosomes 8 and 17, with loss of material on the short arm; 4) structural abnormalities involving chromosome 11; and 5) loss of chromosome Y. The TCC case also exhibited structural abnormalities of chromosome 9, resulting in loss of 9q. The combined G-banding and M-FISH findings could help reveal regions potentially involved in bladder tumorigenesis. 相似文献
5.
Antonio M. Calafiore Antonio Totaro Nicola Testa Cosimo Sacra Gaetano Castellano Stefano Guarracini Massimo Di Marco Sotirios Prapas Mario Gaudino Roberto Lorusso Domenico Paparella Michele Di Mauro 《Journal of cardiac surgery》2021,36(1):247-259
In secondary mitral regurgitation, the concept that the mitral valve (MV) is an innocent bystander, has been challenged by many studies in the last decades. The MV is a living structure with intrinsic plasticity that reacts to changes in stretch or in mechanical stress activating biohumoral mechanisms that have, as purpose, the adaptation of the valve to the new environment. If the adaptation is balanced, the leaflets increase both surface and length and the chordae tendineae lengthen: the result is a valve with different characteristics, but able to avoid or to limit the regurgitation. However, if the adaptation is unbalanced, the leaflets and the chords do not change their size, but become stiffer and rigid, with moderate or severe regurgitation. These changes are mediated mainly by a cytokine, the transforming growth factor‐β (TGF‐β), which is able to promote the changes that the MV needs to adapt to a new hemodynamic environment. In general, mild TGF‐β activation facilitates leaflet growth, excessive TGF‐β activation, as after myocardial infarction, results in profibrotic changes in the leaflets, with increased thickness and stiffness. The MV is then a plastic organism, that reacts to the external stimuli, trying to maintain its physiologic integrity. This review has the goal to unveil the secret life of the MV, to understand which stimuli can trigger its plasticity, and to explain why the equation “large heart = moderate/severe mitral regurgitation” and “small heart = no/mild mitral regurgitation” does not work into the clinical practice. 相似文献
6.
Pyrgaki Konstantina Argyraki Ariadne Kelepertzis Efstratios Botsou Fotini Megremi Ifigeneia Karavoltsos Sotirios Dassenakis Emmanuel Mpouras Thanasis Dermatas Dimitrios 《Bulletin of environmental contamination and toxicology》2021,106(3):446-452
Bulletin of Environmental Contamination and Toxicology - The holistic approach of Driver-Pressure-State-Impact-Response (DPSIR) methodology was applied to selected Cr(VI) impacted groundwater... 相似文献
7.
The use of insecticides continues to be a basic tool in pest management, since there are many pest situations for which there are no known alternative management methods. However, the harmful effects of insecticides against beneficial Insects continuous to be a serious problem. Poisoning of bee pollinators is a serious adverse effect of insecticide use which leads to a decrease in insect population, to reduction of honey yields, to destruction of plant communities, to insecticide residues in food, and to a significant loss of beekeepers' income. In bee poisoning, the identification of the responsible toxicant is necessary by both environmental and biological monitoring, to prevent bee poisoning and for the protection of public health. The different aspects of bee poisoning with anticholinesterase insecticides are discussed in detail. 相似文献
8.
Panagiotis M. Angelopoulos Nikolaos Rafael Vrithias Zacharias Viskadourakis Petros Tsakiridis Konstantinos C. Vasilopoulos Antonis Peppas Georgios Asimakopoulos Anastasia V. Spyrou Michael A. Karakassides Maria Taxiarchou George Kenanakis 《Materials》2022,15(14)
The use of amorphous microspheres as filler in composites is promising due to their light weight, low cost, incombustibility, and the ability to alter relevant properties of the final composite. Contrary to glass spheres, perlite microspheres are much cheaper and can be tailor-made to facilitate purpose-oriented alteration of the final composite. We report the use of perlite microspheres for the preparation of: (1) composites, through a compression molding (hot pressing) technique; and (2) composite filaments, in a single screw extruder, as well as their use for sample printing through Fused Deposition Modeling (FDM). Proper characterization of the produced composites allows for their evaluation in terms of physical, thermal, and mechanical properties and with regards to the manufacturing technique, the filler fraction, and size. Composite samples of acceptable quality in terms of filler survival and dispersion as well as mechanical properties were produced through compression molding using fine expanded perlite microspheres (<90 μm) up to an infill ratio of 40 vol.%. Fine fillers (<90 μm) performed well in FDM, allowing printing of composite dogbone samples with a higher Young’s modulus and elongation and similar ultimate tensile strength compared to benchmark, up to an infill ratio of 20 vol.%. Composite samples present a slightly lower burning rate compared to those produced solely by ABS. Perlite microspheres present good workability in both applications, possessing satisfactory performance as filler in the composites, and can thus be assumed a promising multifunctional filler for various thermoplastics considering their low price, environmental impact, and fire rating. 相似文献
9.
To examine the existing evidence on the relationship between periodontal disease and adverse pregnancy outcomes, we conducted a systematic review of studies published up to December 2006. Studies published in full text were identified by searching computerized databases (e.g., MEDLINE, EMBASE). A meta-analysis was performed to pool the effect size of the clinical trials. Forty-four studies were identified (26 case-control studies, 13 cohort studies, and 5 controlled trials). The studies focused on preterm low birth weight, low birth weight, preterm birth, birth weight by gestational age, miscarriage or pregnancy loss, preeclampsia, and gestational diabetes mellitus. Of the chosen studies, 29 suggested an association between periodontal disease and increased risk of adverse pregnancy outcome (odds ratios [ORs] ranging from 1.10 to 20.0) and 15 found no evidence of an association (ORs ranging from 0.78 to 2.54). A meta-analysis of the clinical trials suggested that oral prophylaxis and periodontal treatment may reduce the rate of preterm low birth weight (pooled risk ratio (RR): 0.53, 95% confidence interval [CI]: 0.30-0.95, P < 0.05), but did not significantly reduce the rates of preterm birth (pooled RR: 0.79, 95% CI: 0.55-1.11, P > 0.05) or low birth weight (pooled RR: 0.86, 95% CI: 0.58%1.29, P > 0.05). The authors conclude that periodontal disease may be associated with increased risk of adverse pregnancy outcomes. More methodologically rigorous studies are needed in this field. Currently, there is insufficient evidence to support the provision of periodontal treatment during pregnancy for the purpose of reducing adverse pregnancy outcomes. TARGET AUDIENCE: Obstetricians & Gynecologists, Family Physicians. LEARNING OBJECTIVES: After completion of this article, the reader should be able to state that the published literature is not vigorous to clinically link periodontal disease and/or its treatment to specific adverse pregnancy outcomes, and explain that more rigorous studies with world-wide agreed-upon definitions are particularly needed before periodontal disease treatment can be recommended. 相似文献
10.
Botaitis S Polychronidis A Pitiakoudis M Perente S Simopoulos C 《Surgical laparoscopy, endoscopy & percutaneous techniques》2008,18(2):157-161
The relationship between sex and outcome after laparoscopic surgery for symptomatic cholelithiasis remains unclear. The purpose of this study was to determine the influence of sex on the clinical presentation of patients with symptomatic gallstone disease and the clinical outcomes of laparoscopic cholecystectomy. The rates of conversion to open cholecystectomy, complication rates, operative times, and lengths of hospital stay were compared between the sexes. Compared with female patients, males were significantly older and more likely to have coexisting cardiovascular disease, previous upper abdominal surgery, previous hospitalization for acute cholecystitis and pancreatitis, acute cholecystitis, and suppurative cholecystitis (such as empyema), conversions, and complications. The mortality rate was nil. Analyses revealed an independent effect of sex on the prevalence of complications, even when including all of the major confounding factors in the model. In contrast, the effect of sex on conversion to open cholecystectomy was not significant when controlling for patient age. Operative time and postoperative hospital stay were significantly longer in males than in females. The tendency of male patients to have cholecystitis of greater severity should remind surgeons of the need to inform patients about the higher conversion rate among male patients, to reduce the disappointment of a large laparotomy wound or prolonged recovery period. On the other hand, there may be an increased need for surgeons to strongly advice male patients with symptomatic cholelithiasis to undergo early intervention. 相似文献