全文获取类型
收费全文 | 3697篇 |
免费 | 221篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 19篇 |
儿科学 | 86篇 |
妇产科学 | 74篇 |
基础医学 | 623篇 |
口腔科学 | 88篇 |
临床医学 | 283篇 |
内科学 | 796篇 |
皮肤病学 | 89篇 |
神经病学 | 516篇 |
特种医学 | 92篇 |
外科学 | 364篇 |
综合类 | 25篇 |
一般理论 | 1篇 |
预防医学 | 236篇 |
眼科学 | 47篇 |
药学 | 288篇 |
中国医学 | 8篇 |
肿瘤学 | 293篇 |
出版年
2023年 | 49篇 |
2022年 | 83篇 |
2021年 | 155篇 |
2020年 | 95篇 |
2019年 | 99篇 |
2018年 | 125篇 |
2017年 | 91篇 |
2016年 | 107篇 |
2015年 | 127篇 |
2014年 | 158篇 |
2013年 | 203篇 |
2012年 | 279篇 |
2011年 | 252篇 |
2010年 | 149篇 |
2009年 | 145篇 |
2008年 | 215篇 |
2007年 | 231篇 |
2006年 | 192篇 |
2005年 | 184篇 |
2004年 | 161篇 |
2003年 | 133篇 |
2002年 | 142篇 |
2001年 | 34篇 |
2000年 | 20篇 |
1999年 | 17篇 |
1998年 | 24篇 |
1997年 | 23篇 |
1996年 | 13篇 |
1995年 | 23篇 |
1994年 | 8篇 |
1993年 | 11篇 |
1992年 | 17篇 |
1991年 | 20篇 |
1990年 | 13篇 |
1989年 | 24篇 |
1988年 | 25篇 |
1987年 | 14篇 |
1986年 | 20篇 |
1985年 | 23篇 |
1984年 | 18篇 |
1983年 | 16篇 |
1982年 | 12篇 |
1981年 | 10篇 |
1980年 | 8篇 |
1978年 | 12篇 |
1977年 | 11篇 |
1975年 | 8篇 |
1974年 | 7篇 |
1968年 | 12篇 |
1957年 | 10篇 |
排序方式: 共有3928条查询结果,搜索用时 390 毫秒
1.
Karl Johnson Katherine W. Saylor Isabella Guynn Karen Hicklin Jonathan S. Berg Kristen Hassmiller Lich 《Genetics in medicine》2022,24(2):262-288
PurposeUnderstanding the value of genetic screening and testing for monogenic disorders requires high-quality, methodologically robust economic evaluations. This systematic review sought to assess the methodological quality among such studies and examined opportunities for improvement.MethodsWe searched PubMed, Cochrane, Embase, and Web of Science for economic evaluations of genetic screening/testing (2013-2019). Methodological rigor and adherence to best practices were systematically assessed using the British Medical Journal checklist.ResultsAcross the 47 identified studies, there were substantial variations in modeling approaches, reporting detail, and sophistication. Models ranged from simple decision trees to individual-level microsimulations that compared between 2 and >20 alternative interventions. Many studies failed to report sufficient detail to enable replication or did not justify modeling assumptions, especially for costing methods and utility values. Meta-analyses, systematic reviews, or calibration were rarely used to derive parameter estimates. Nearly all studies conducted some sensitivity analysis, and more sophisticated studies implemented probabilistic sensitivity/uncertainty analysis, threshold analysis, and value of information analysis.ConclusionWe describe a heterogeneous body of work and present recommendations and exemplar studies across the methodological domains of (1) perspective, scope, and parameter selection; (2) use of uncertainty/sensitivity analyses; and (3) reporting transparency for improvement in the economic evaluation of genetic screening/testing. 相似文献
2.
Flavia Temperilli Aldona Rina Isabella Massimi Anna Lisa Montemari Maria Luisa Guarino Alessandra Zicari 《Platelets》2015,26(8):783-787
Serum thromboxane-B2 (TxB2), together with arachidonic acid (AA)-induced platelet aggregation, are, at the moment, the most used tests to identify patients displaying high on-aspirin treatment platelet reactivity (HAPR). Both tests are specific for aspirin action on cyclooxygenase-1. While the correlation between serum TxB2 assay and clinical outcome is established, data are conflicting with regard to aspirin treatment and a possible association with AA-stimulated platelet markers and clinical outcome. To understand such discrepancy, we performed a retrospective study to compare both assays. We collected data from 132 patients receiving a daily dose of aspirin (100?mg/day) and data from 48 patients receiving aspirin on alternate days. All Patients who received a daily dose of aspirin were studied for AA-induced platelet aggregation together with serum TxB2 levels and AA-induced TxB2 formation was also studied in 71 patients out of entire population. Consistent with recommendations in the literature, we defined HAPR by setting a cut-off point at 3.1?ng/ml for serum levels of thromboxane B2 and 20% for AA-induced platelet aggregation. According to this cut-off point, we divided our overall population into two groups: (1) TxB2?<?3.1?ng/ml and (2) TxB2?>?3.1?ng/ml. We found low agreement between such tests to identify patients displaying HAPR. Our results show that AA-induced platelet aggregation >20% identify a smaller number of HAPR patients in comparison with TxB2. A good correlation between serum TxB2 and arachidonic acid-induced TxB2 production was found (r?=?0.76619). 相似文献
3.
Ana M. Gómez Angelica Imitola Diana Henao Maira García-Jaramillo Marga Giménez Clara Viñals Bruno Grassi Mariana Torres Isabella Zuluaga Oscar Mauricio Muñoz Martin Rondón Fabián León-Vargas Ignacio Conget 《Diabetes & Metabolic Syndrome: Clinical Research & Reviews》2021,15(1):267-272
Background and aimsDespite using sensor-augmented pump therapy (SAPT) with predictive low-glucose management (PLGM), hypoglycemia is still an issue in patients with type 1 Diabetes (T1D). Our aim was to determine factors associated with clinically significant hypoglycemia (<54 mg/dl) in persons with T1D treated with PLGM-SAPT.Methodology: This is a multicentric prospective real-life study performed in Colombia, Chile and Spain. Patients with T1D treated with PLGM-SAPT, using sensor ≥70% of time, were included. Data regarding pump and sensor use patterns and carbohydrate intake from 28 consecutive days were collected. A bivariate and multivariate Poisson regression analysis was carried out, to evaluate the association between the number of events of <54 mg/dl with the clinical variables and patterns of sensor and pump use.Results188 subjects were included (41 ± 13.8 years-old, 23 ± 12 years disease duration, A1c 7.2% ± 0.9). The median of events <54 mg/dl was four events/patient/month (IQR 1–10), 77% of these events occurred during day time. Multivariate analysis showed that the number of events of hypoglycemia were higher in patients with previous severe hypoglycemia (IRR1.38; 95% CI 1.19–1.61; p < 0.001), high glycemic variability defined as Coefficient of Variation (CV%) > 36% (IRR 2.09; 95%CI 1.79–2.45; p < 0.001) and hypoglycemia unawareness. A protector effect was identified for adequate sensor calibration (IRR 0.77; 95%CI 0.66–0.90; p:0.001), and the use of bolus wizard >60% (IRR 0.74; 95%CI 0.58–0.95; p:0.017).ConclusionIn spite of using advanced SAPT, clinically significant hypoglycemia is still a non-negligible risk. Only the identification and intervention of modifiable factors could help to prevent and reduce hypoglycemia in clinical practice. 相似文献
4.
Brenda Laky Isabella Alram Julia K. Frank Leo Pauzenberger Werner Anderl Karl-Heinz Wagner Philipp R. Heuberer 《Journal of orthopaedic research》2020,38(9):2074-2082
Increasing numbers of arthroplasties are also accompanied by postoperative infections. The main purpose was to evaluate preoperative serum bilirubin levels between patients with and without infections after shoulder and knee arthroplasties. For this retrospective case-control single-center study, a total of 108 patients were extracted from a prospectively collected database. Eighteen patients with infections after shoulder (n = 8) and knee (n = 10) arthroplasty were matched by age, gender, and implant type in a 1:5-scenario to 90 patients (40 shoulders and 50 knees) without postoperative infection. Demographic data, preoperative blood parameters, and postoperative infection-related outcomes were evaluated. Total bilirubin was the only preoperative parameter significantly different between the infection (8.21 ± 3.25 μmol/L or 0.48 ± 0.19 mg/dL) and noninfection (10.78 ± 4.62 μmol/L or 0.63 ± 0.27 mg/dL; P = .014) group, while C-reactive protein and other liver parameters were similar between the groups. Significantly more controls (92.1%) had preoperative bilirubin levels above 8.72 μmol/L or 0.51 mg/dL than cases (7.9%; P = .007). The 5-year infection survival-rate was 65.6% for patients with preoperative bilirubin levels < 8.72 μmol/L or < 0.51 mg/dL and 91.2% with ≥ 8.72 μmol/L or ≥ 0.51 mg/dL. Mildly decreased preoperative bilirubin levels with a cutoff at 8.72 μmol/L or 0.51 mg/dL were significantly associated to patients with infections after shoulder and knee arthroplasty. There were no differences in other blood parameters or comorbidities between patients with infections and their matched-controls. 相似文献
5.
A high resolution depth attenuation product (Kdhires) was developed using MODIS 500 m and 250 m spectral bands. The Kdhires was compared with Wang’s operational Kd for the Chesapeake Bay. Minimal differences were observed between the two methods, with greatest deviation occurring in areas of high turbidity in the tributaries. After tuning the new Kdhires, the mean absolute error and bias between the two algorithms was 0.22 m?1 and 0.026 m?1, indicating good agreement. Higher spatial resolution provides for improved retrievals along the coast and into the narrow sections of the tributaries, coinciding with areas of concern to estuarine health and coastal management applications. 相似文献
6.
Isabella Sch?ll George Boltz-Nitulescu Erika Jensen-Jarolim 《Journal of controlled release》2005,104(1):1-27
For the treatment of infectious diseases, cancer and allergy, the directed induction of an appropriate immune response is the ultimate goal. Therefore, with the development of pure, often very small proteins, peptides or DNA by molecular biology techniques, the research for suitable adjuvants or delivery systems became increasingly important. Particle formulations are made of a variety of materials, including lipids, proteins or amino acids, polysaccharides, polyacrylic substances or organic acids. Microparticles serve as vehicles and provide a depot for the entrapped or coupled antigen. The release occurs in a pulsatile or continuous manner, a feature, which is well controllable for many particulate systems. Particles attract antigen presenting cells to the administration site, thereby guaranteeing the efficient presentation of the antigen to the immune system. Importantly, particles also protect the entrapped substance. This is especially necessary after oral application to avoid gastric or tryptic breakdown. In this article, the design and construction of different antigen delivery systems and their immune effects, with special focus on the suitability for allergy treatment, are discussed. 相似文献
7.
Rebecca P. Ang Robert M. Klassen Wan Har Chong Vivien S. Huan Isabella Y.F. Wong Lay See Yeo Lindsey L. Krawchuk 《Journal of adolescence》2009,32(5):1225-1237
We provide further evidence for the two-factor structure of the 9-item Academic Expectations Stress Inventory (AESI) using confirmatory factor analysis on a sample of 289 Canadian adolescents and 310 Singaporean adolescents. Examination of measurement invariance tests the assumption that the model underlying a set of scores is directly comparable across groups. This study also examined the cross-cultural validity of the AESI using multigroup confirmatory factor analysis across both the Canadian and Singaporean adolescent samples. The results suggested cross-cultural invariance of form, factor loadings, and factor variances and covariances of the AESI across both samples. Evidence of AESI's convergent and discriminant validity was also reported. Findings from t-tests revealed that Singaporean adolescents reported a significantly higher level of academic stress arising from self expectations, other expectations, and overall academic stress, compared to Canadian adolescents. Also, a larger cross-cultural effect was associated with academic stress arising from other expectations compared with academic stress arising from self expectations. 相似文献
8.
Nicoletta Desideri Isabella Sestili Maria Luisa Stein Stefano Manarini Giuseppe Dell'Elba Chiara Cerletti 《Archiv der Pharmazie》1997,330(4):100-106
6-[(4-Quinolinyl)oxy]hexanoic acids and the corresponding esters were designed and synthesized as inhibitors of the production of arachidonic acid metabolites. The inhibitory activities were assayed in vitro by evaluation of serum leukotriene B4 and thromboxane B2 production. While all 6-[(4-quinolinyl)oxy]hexanoic acids and their esters proved to be inactive, the N-alkyl-4-quinolones, obtained as by-products in their synthesis, were found to be a new class of leukotriene biosynthesis inhibitors. 相似文献
9.
Sbrana Isabella; Puliti Aldamaria; Seidel Albrecht; Glatt Hansruedi; Turchi Gino 《Mutagenesis》1995,10(6):505-512
Regioisomers of pyrene and benzo[a]pyrene quinones were testedfor their ability to induce structural and numerical aberrationsand spindle disturbance in Chinese hamster epithelial liver(CHEL) cells in culture. All quinones tested were clastogenicPyrene-1,8-quinone (P-1,8-Q) and benzo[a]pyrene3,6quinone(BP-3,6-Q) induced strikingly high levels of triradials. Inaddition, dicentrics and ring chromosomes were very common inBP-3,6-Q-treated cultures. Isomers of these compounds, pyrene-1,6-quinone(P-1,6-Q) and benzo[a]pyrene-1,6-quinone (BP-1,6-Q), inducedunobtrusive patterns of chromosomal aberrations. We suspectthat the P-1,8-Q and BP-3,6-Q moieties bound to the DNA werestill reactive, and formed crosslinks and/or underwent redoxcycling leading to high local concentrations of reactive oxygenspecies. In addition, P-1,8-Q and BP-3,6-Q induced c-mitoses,hyperdiploidies and polyploidies, in particular endoreduplications.These effects were not seen with the other two test compounds,or they were only detected at the highest concentrations used,which were strongly cytotoxic (c-mitoses with P-1,6-Q, polyploidieswith BP-1,6-Q).
6To whom correspondence should be addressed at: European Centre for the Validation of Alternative Methods (ECVAM), Joint Research Centre (JRC), TP58O, 121020 Ispra, Italy 相似文献
10.
Influence of pneumoperitoneum on small bowel anastomoses: a histological analysis in the rat model. 总被引:3,自引:0,他引:3
R Rosch M Stumpf K Junge D Drinjakovic A Schachtrupp M Afify V Schumpelick 《Journal of investigative surgery》2005,18(2):63-69
Laparoscopic techniques are increasingly applied for the treatment of diverse gastrointestinal diseases. With regard to reports of a pronounced decrease of intra-abdominal blood flow with increasing intra-abdominal pressure, the present study investigates the impact of pressure and gas type on ischemia in small bowel anastomoses in the rat model. Laparotomy and ileoileal anastomosis were performed in 39 male Sprague-Dawley rats. A CO2 or helium pneumoperitoneum of 3 mm Hg or of 6 mm Hg was maintained before and after anastomoses. Rats in the control group received no pneumoperitoneum. Animals were sacrificed after 5 d, and the anastomotic region was explanted for subsequent histopathological examinations. In hematoxylin and eosin (HE)-stained sections, the Chiu score, villi configuration, and number of goblet cells were analyzed. Proliferation (Ki67) and expression of a matrix metalloproteinase (MMP-8) were examined by immunohistochemistry. Mucosal damage according to the scoring system by Chiu, the number of goblet cells, the villus length, the proliferation (Ki67), and the submucosal expression of MMP-8 was similar in all groups. Our results suggest that within a certain range of pressures and time, laparoscopic assisted surgery using CO2 pneumoperitoneum can be performed safely. Helium gas offers no advantages over CO2. 相似文献