全文获取类型
收费全文 | 3648篇 |
免费 | 208篇 |
国内免费 | 21篇 |
专业分类
耳鼻咽喉 | 44篇 |
儿科学 | 45篇 |
妇产科学 | 38篇 |
基础医学 | 571篇 |
口腔科学 | 171篇 |
临床医学 | 309篇 |
内科学 | 823篇 |
皮肤病学 | 102篇 |
神经病学 | 260篇 |
特种医学 | 168篇 |
外科学 | 538篇 |
综合类 | 17篇 |
预防医学 | 177篇 |
眼科学 | 42篇 |
药学 | 252篇 |
中国医学 | 5篇 |
肿瘤学 | 315篇 |
出版年
2023年 | 24篇 |
2022年 | 61篇 |
2021年 | 79篇 |
2020年 | 68篇 |
2019年 | 77篇 |
2018年 | 81篇 |
2017年 | 62篇 |
2016年 | 80篇 |
2015年 | 98篇 |
2014年 | 121篇 |
2013年 | 172篇 |
2012年 | 281篇 |
2011年 | 297篇 |
2010年 | 180篇 |
2009年 | 167篇 |
2008年 | 242篇 |
2007年 | 258篇 |
2006年 | 264篇 |
2005年 | 241篇 |
2004年 | 205篇 |
2003年 | 211篇 |
2002年 | 173篇 |
2001年 | 38篇 |
2000年 | 13篇 |
1999年 | 36篇 |
1998年 | 41篇 |
1997年 | 34篇 |
1996年 | 32篇 |
1995年 | 19篇 |
1994年 | 13篇 |
1993年 | 20篇 |
1992年 | 16篇 |
1991年 | 6篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1975年 | 4篇 |
1974年 | 5篇 |
1969年 | 4篇 |
1964年 | 6篇 |
1958年 | 4篇 |
1955年 | 7篇 |
1954年 | 4篇 |
排序方式: 共有3877条查询结果,搜索用时 0 毫秒
21.
22.
23.
Reinheimer TM 《BMC pregnancy and childbirth》2007,7(Z1):S15
Background
Preterm labour (PTL) is a major cause of neonatal mortality and morbidity, and oxytocin (OT) antagonists are potential tocolytics. Atosiban (TRACTOCILE) is a mixed vasopressin V1A/OT antagonist registered for acute treatment of PTL in Europe. Other off-label drugs have serious side effects. Barusiban is a selective OT antagonist which has reached clinical development. A monkey model with OT-induced PTL was developed to compare barusiban and atosiban. In addition, the feasibility for long-term treatment of PTL with barusiban was explored.Methods
Conscious pregnant cynomolgus monkeys were monitored for intrauterine pressure (IUP). A sensor for IUP was implanted into the amniotic cavity, and biopotential sensors for electromyogram were attached to the uterus. For short-term experiments, individual low-dose OT infusions induced stable submaximal uterine contractions. Barusiban and atosiban were administered either as intravenous bolus or infusion at high or low doses. For long-term treatment, low-dose OT was infused daily for 3–6 hours to mimic PTL. In addition, continuous high-dose infusions of barusiban (150 μg kg-1 h-1) or fenoterol (3 μg kg-1 h-1) were administered.Results
Contractions of 15–40 mmHg were induced with individual OT infusions at 5–90 mU kg-1 h-1, and no OT-related desensitization occurred. Correlation was demonstrated between electromyograms and IUP curves. Barusiban was well tolerated and its potency was 4 times higher than atosiban's. Barusiban and atosiban demonstrated >95% efficacy. However, barusiban's duration of action was >13 hours (atosiban's 1–3 hours) and reversible with high-dose OT in emergency situations. OT control and fenoterol-treated monkeys delivered preterm (ca. day 154) and showed an increase in overall IUP. Barusiban-treated animals delivered normally following end of treatment (ca. day 163).Conclusion
The presented telemetry model provides an excellent method to evaluate PTL drug candidates. OT induced stable repetitive contractions and no desensitisation. Barusiban and atosiban demonstrated high efficacy and rapid onset of action. Barusiban, a selective OT antagonist has higher potency and prolonged duration of action than atosiban. Barusiban effectively suppressed IUP during daily OT-challenges, delayed labour, and prolonged monkeys' pregnancy till term.24.
Imaging proliferation in lung tumors with PET: 18F-FLT versus 18F-FDG. 总被引:19,自引:0,他引:19
Andreas K Buck Gisela Halter Holger Schirrmeister J?rg Kotzerke Imke Wurziger Gerhard Glatting Torsten Mattfeldt Bernd Neumaier Sven N Reske Martin Hetzel 《Journal of nuclear medicine》2003,44(9):1426-1431
Recently, the thymidine analog 3'-deoxy-3'-(18)F-fluorothymidine (FLT) was suggested for imaging tumoral proliferation. In this prospective study, we examined whether (18)F-FLT better determines proliferative activity in newly diagnosed lung nodules than does (18)F-FDG. METHODS: Twenty-six patients with pulmonary nodules on chest CT were examined with PET and the tracers (18)F-FDG and (18)F-FLT. Tumoral uptake was determined by calculation of standardized uptake value (SUV). Within 2 wk, patients underwent resective surgery or had core biopsy. Proliferative activity was estimated by counting nuclei stained with the Ki-67-specific monoclonal antibody MIB-1 per total number of nuclei in representative tissue specimens. The correlation between the percentage of proliferating cells and the SUVs for (18)F-FLT and (18)F-FDG was determined using linear regression analysis. RESULTS: Eighteen patients had malignant tumors (13 with non-small cell lung cancer [NSCLC], 1 with small cell lung cancer, and 4 with pulmonary metastases from extrapulmonary tumors); 8 had benign lesions. In all visible lesions, mean (18)F-FDG uptake was 4.1 (median, 4.4; SD, 3.0; range, 1.0-10.6), and mean (18)F-FLT uptake was 1.8 (median, 1.2; SD, 2.0; range, 0.8-6.4). Statistical analysis revealed a significantly higher uptake of (18)F-FDG than of (18)F-FLT (Mann-Whitney U test, P < 0.05). (18)F-FLT SUV correlated better with proliferation index (P < 0.0001; r = 0.92) than did (18)F-FDG SUV (P < 0.001; r = 0.59). With the exception of 1 carcinoma in situ, all malignant tumors showed increased (18)F-FDG PET uptake. (18)F-FLT PET was false-negative in the carcinoma in situ, in another NSCLC with a low proliferation index, and in a patient with lung metastases from colorectal cancer. Increased (18)F-FLT uptake was related exclusively to malignant tumors. By contrast, (18)F-FDG PET was false-positive in 4 of 8 patients with benign lesions. CONCLUSION: (18)F-FLT uptake correlates better with proliferation of lung tumors than does uptake of (18)F-FDG and might be more useful as a selective biomarker for tumor proliferation. 相似文献
25.
Torsten Fredriksson M.D. Jerry K. Bigelow M.T. 《Archives of environmental & occupational health》2013,68(6):663-667
Repeated inhalation of the vapors of bis(chloromethyl) ether and chloromethyl methyl ether at one and two ppm, respectively, and of the aerosol of urethan at approximately 138 ppm, resulted in an increase in incidence of pulmonary adenomas in strain A mice. In addition, the high toxicity of the two haloethers and the general lack of properties irritating to the upper respiratory tract in all three compounds pose an insidious industrial handling hazard. 相似文献
26.
Else-Marie Dalsgaard Jesper O. Christensen Mette Vinter Skriver Knut Borch-Johnsen Torsten Lauritzen Annelli Sandbaek 《Primary Care Diabetes》2010,4(4):223-229
AimTo examine attendance, number of people with T2DM and costs of three different stepwise screening strategies for T2DM in general practice (GP).MethodsDiabetes risk questionnaires were mailed to individuals aged 40–69 years from 45 general practices in 2001–2002 and individuals at high risk for T2DM, were asked to contact their GP to arrange a screening test. In 2005–2006, 26 general practices were randomised into two different opportunistic screening programmes (OP-direct and OP-subsequent) and risk questionnaires were distributed to individuals aged 40–69 years during GP consultations. In the OP-direct approach, high-risk individuals were offered to start the screening during the actual consultation while high-risk individuals in the OP-subsequent approach, were invited to a screening test at a later date. We report attendance, number of people with T2DM and costs of each screening approach.ResultsThe mail-distributed approach identified 0.8% of the target population with T2DM, the OP-direct approach and the OP-subsequent approach, 0.9% and 0.5% respectively. Cost per person with T2DM was in the mail-distributed approach: € 1058, OP-direct approach: € 707 and the OP-subsequent approach: € 727.ConclusionThis study indicates that opportunistic screening identifies the same level of unknown diabetes as a mail-distributed approach but with lower costs. 相似文献
27.
Karsten Gavenis †Bernhard Schmidt-Rohlfing Stefan Andereya Torsten Mumme ‡Ulrich Schneider Ralf Mueller-Rath 《Artificial organs》2010,34(1):79-83
The purpose of this study was to evaluate the potential value of a cell-free collagen type I gel plug for the treatment of focal cartilage defects. Cellular migration and proliferation was addressed in vitro, and the formation of repair tissue in a nude mouse-based defect model. A cell-free plug made of collagen type I was placed in the center of an incubation plate. Surrounding space was filled with a collagen type I gel (Arthro Kinetics, Esslingen, Germany) seeded with 2 × 105 human articular chondrocytes/mL gel. After cultivation for up to 6 weeks in vitro, samples were subject to histological and immunohistochemical staining and gene expression analysis. Subsequently, chondral defects of human osteochondral blocks were treated with the plug, and specimens were cultivated subcutaneously in nude mice for 6 weeks. The repair tissue was evaluated macroscopically, and collagen type II production was investigated immunohistochemically. In vitro, morphology of immigrated cells did not show any differences, as did collagen type II gene expression. After 4 weeks, the plug was homogeneously inhabited. After 6 weeks of cultivation in nude mice, collagen gel plug treatment led to a macroscopically excellent repair tissue. Histological staining revealed a tight bonding, and the collagen gel plug started to be remodeled. We conclude that the novel collagen gel plug device offers an environment favorable for the migration of articular chondrocytes and leads to a good-quality repair tissue in the nude mouse model. The arthroscopic transplantation of a collagen gel plug may be one option in the treatment of focal cartilage defects. 相似文献
28.
29.
Reda T Plugge CM Abram NJ Hirst J 《Proceedings of the National Academy of Sciences of the United States of America》2008,105(31):10654-10658
Carbon dioxide (CO2) is a kinetically and thermodynamically stable molecule. It is easily formed by the oxidation of organic molecules, during combustion or respiration, but is difficult to reduce. The production of reduced carbon compounds from CO2 is an attractive proposition, because carbon-neutral energy sources could be used to generate fuel resources and sequester CO2 from the atmosphere. However, available methods for the electrochemical reduction of CO2 require excessive overpotentials (are energetically wasteful) and produce mixtures of products. Here, we show that a tungsten-containing formate dehydrogenase enzyme (FDH1) adsorbed to an electrode surface catalyzes the efficient electrochemical reduction of CO2 to formate. Electrocatalysis by FDH1 is thermodynamically reversible—only small overpotentials are required, and the point of zero net catalytic current defines the reduction potential. It occurs under thoroughly mild conditions, and formate is the only product. Both as a homogeneous catalyst and on the electrode, FDH1 catalyzes CO2 reduction with a rate more than two orders of magnitude faster than that of any known catalyst for the same reaction. Formate oxidation is more than five times faster than CO2 reduction. Thermodynamically, formate and hydrogen are oxidized at similar potentials, so formate is a viable energy source in its own right as well as an industrially important feedstock and a stable intermediate in the conversion of CO2 to methanol and methane. FDH1 demonstrates the feasibility of interconverting CO2 and formate electrochemically, and it is a template for the development of robust synthetic catalysts suitable for practical applications. 相似文献
30.
Susanna?Nikolaus Georg?H.?Waetzig Sven?Butzin Monika?Ziolkiewicz Natalie?Al-Massad Florian?Thieme Ulf?L?vgren Birgitte?B.?Rasmussen Torsten?M.?Reinheimer Dirk?Seegert Philip?Rosenstiel Silke?Szymczak Stefan?SchreiberEmail authorView authors OrcID profile 《International journal of colorectal disease》2018,33(7):927-936