全文获取类型
收费全文 | 13042篇 |
免费 | 616篇 |
国内免费 | 38篇 |
专业分类
耳鼻咽喉 | 187篇 |
儿科学 | 260篇 |
妇产科学 | 259篇 |
基础医学 | 2079篇 |
口腔科学 | 243篇 |
临床医学 | 1064篇 |
内科学 | 2496篇 |
皮肤病学 | 232篇 |
神经病学 | 1281篇 |
特种医学 | 762篇 |
外国民族医学 | 1篇 |
外科学 | 1662篇 |
综合类 | 84篇 |
预防医学 | 531篇 |
眼科学 | 627篇 |
药学 | 1170篇 |
中国医学 | 64篇 |
肿瘤学 | 694篇 |
出版年
2022年 | 83篇 |
2021年 | 157篇 |
2020年 | 103篇 |
2019年 | 132篇 |
2018年 | 180篇 |
2017年 | 154篇 |
2016年 | 210篇 |
2015年 | 305篇 |
2014年 | 355篇 |
2013年 | 483篇 |
2012年 | 657篇 |
2011年 | 730篇 |
2010年 | 439篇 |
2009年 | 440篇 |
2008年 | 732篇 |
2007年 | 765篇 |
2006年 | 714篇 |
2005年 | 748篇 |
2004年 | 731篇 |
2003年 | 731篇 |
2002年 | 691篇 |
2001年 | 244篇 |
2000年 | 195篇 |
1999年 | 233篇 |
1998年 | 175篇 |
1997年 | 151篇 |
1996年 | 125篇 |
1995年 | 98篇 |
1994年 | 116篇 |
1993年 | 119篇 |
1992年 | 128篇 |
1991年 | 98篇 |
1990年 | 105篇 |
1989年 | 125篇 |
1988年 | 91篇 |
1987年 | 107篇 |
1986年 | 73篇 |
1985年 | 107篇 |
1984年 | 86篇 |
1983年 | 76篇 |
1982年 | 70篇 |
1981年 | 84篇 |
1980年 | 56篇 |
1979年 | 70篇 |
1978年 | 54篇 |
1977年 | 85篇 |
1976年 | 56篇 |
1975年 | 52篇 |
1974年 | 53篇 |
1973年 | 43篇 |
排序方式: 共有10000条查询结果,搜索用时 166 毫秒
81.
Given the changes of gender roles in this century it is hardly justified to assume constant proportions of alcohol consumption for males and females. The purpose of the study was to reconstruct the consumption trends of males and females in Switzerland since the beginning of the 20th century. Cirrhosis mortality and survey data were used to disaggregate by sex the per capita alcohol consumption based on liver cirrhosis mortality suggests that the evolution of alcohol consumption in Switzerland followed a parallel course for both sexes only until the 1930 s. The low consumption during World War II and the evident increase until the beginning of the '60s seem to have resulted above all from the variations in consumption of beer by men. The decrease in total alcohol consumption observed since the '70s is also most probably due only to men; there is no indication of a decreasing consumption by women. The tendency of male and female consumption patterns to become more similar should be taken into account in the prevention of alcohol misuse. 相似文献
82.
Langenbucher A Seitz B Kus MM Naumann GO 《Investigative ophthalmology & visual science》1999,40(3):582-591
PURPOSE: To demonstrate a mathematical method for decomposition of discrete corneal topography height data into a set of Zernike polynomials and to demonstrate the clinical applicability of these computations in the postkeratoplasty cornea. METHODS: Fifty consecutive patients with either Fuchs' dystrophy (n = 20) or keratoconus (n = 30) were seen at 3 months, 6 months, and 1 year (before suture removal) and again after suture removal following nonmechanical trephination with the excimer laser. Patients were assessed using regular keratometry, corneal topography (TMS-1, simulated keratometry [SimK]), subjective refraction, and best-corrected visual acuity (VA) at each interval. A set of Zernike coefficients with radial degree 8 was calculated to fit two model surfaces: a complete representation (TOTAL) and a representation with parabolic terms only to define an approximate spherocylindrical surface (PARABOLIC). The root mean square error (RMS) was calculated comparing the corneal raw height data with TOTAL (TOTALRMS) and PARABOLIC (PARABOLICRMS). The cylinder of subjective refraction was correlated with the keratometric readings, the SimK, and the respective Zernike parameter. Visual acuity was correlated with the tilt components of the Zernike expansion. RESULTS: The measured corneal surface could be approximated by the composed surface 1 with TOTALRMS < or = 1.93 microm and by surface 2 with PARABOLICRMS < or = 3.66 microm. Mean keratometric reading after suture removal was 2.8+/-0.6 D. At all follow-up examinations, the SimK yielded higher values, whereas the keratometric reading and the refractive cylinder yielded lower values than the respective Zernike parameter. The correlation of the Zernike representation and the refractive cylinder (P = 0.02 at 3 months, P = 0.05 at 6 months and at 1 year, and P = 0.01 after suture removal) was much better than the correlation of the SimK and refractive cylinder (P = 0.3 at 3 months, P = 0.4 at 6 months, P = 0.2 at 1 year, and P = 0.1 after suture removal). Visual acuity increased from 0.23+/-0.10 at the 3-month evaluation to 0.54+/-0.19 after suture removal. After suture removal, there was a statistically significant inverse correlation between VA and tilt (P = 0.02 in patients with keratoconus and P = 0.05 in those with Fuchs' dystrophy). CONCLUSIONS: Zernike representation of corneal topography height data renders a reconstruction of clinically relevant corneal topography parameters with a marked reduction of redundance and a small error. Correlation of amount/axis of refractive cylinder with respective Zernike parameters is more accurate than with keratometry or respective SimK values of corneal topography analysis. 相似文献
83.
"Orientation teeth" in non-mechanical laser corneal trephination for penetrating keratoplasty: 2.94 microm Er:YAG v 193 nm ArF excimer laser. 下载免费PDF全文
A. Behrens B. Seitz M. Kuchle A. Langenbucher M. Kus C. Rummelt G. Naumann 《The British journal of ophthalmology》1999,83(9):1008-1012
BACKGROUND/AIMS: "Orientation teeth" at the donor trephination margin and correspondent "notches" at the host margin facilitate graft orientation and avoid "horizontal torsion" induced by asymmetric suture placement. In this study the quality and reproducibility of these structures created by non-mechanical laser corneal trephination were compared using two laser emissions. METHODS: The procedure was performed in 20 enucleated pigs' eyes using open metal masks with eight "orientation teeth/notches" (0.3 x 0.15 mm, base x height), an automated globe rotation device, and either a 193 nm ArF excimer laser or a Q switched 2.94 microm Er:YAG laser. "Teeth/notches" were analysed by planimetry and scanning electron microscopy (SEM). RESULTS: Mean size was 0.30 (0.027) x 0. 16 (0.017) mm for "teeth" and 0.30 (0.035) x 0.15 (0.021) mm for "notches" (excimer), and 0.31 (0.022) x 0.16 (0.015) mm and 0.30 (0.031) x 0.14 (0.021) mm respectively (Er:YAG). Overall, variability of notches was higher than that of teeth. By SEM, comparable cut regularity and sustained ablation profile were observed with both lasers. However, the corneal surface at the cut edge appeared slightly elevated (=35 microm) in the Er:YAG group. CONCLUSION: Orientation teeth/notches resembling those obtained with the excimer laser can be created using the Q switched Er:YAG laser, with potential advantages of lower costs, convenient equipment size, and solid state safety. 相似文献
84.
85.
Frank Rösch Hans Herzog Cornelius Plag Bernd Neumaier Ulrike Braun Hans-Willhelm Müller-Gärtnere Gerhard Stöcklin 《European journal of nuclear medicine and molecular imaging》1996,23(8):958-966
Yttrium-90 is used for palliative therapy for the treatment of skeletal metastases, but because it is a pure - emitter, data on the pharmacokinetics and radiation doses to metastases and unaffected organs are lacking. To obtain such data, the present study employed yttrium-86 as a substitute for90Y, with detection by positron emission tomography (PET). The study compared the properties of two different86Y complexes —86y-citrate and86Y -ethylene diamine tetramethylene phosphonate (EDTMP) — in ten patients with prostatic cancer who had developed multiple bone metastases (the ten patients being divided into two groups of five). Early dynamics were measured up to 1 h post injection (p.i.) over the liver region, followed by subsequent whole-body PET scans up to 3 days p.i. Absolute uptake data were determined for normal bone, bone metastases, liver and kidney. Radiation doses were calculated according to the MIRD recommendations. Based on the pharmacokinetic measurements of the distribution of the86Y complexes, it was possible to calculate radiation doses for the bone metastases and the red bone marrow delivered by complexes containing90Y. In 1 cm3 of bone metastasis, doses of 26±11 mGy/MBq and 18±2 mGy/MBq were determined per MBq of injected90Y- citrate and90Y- EDTMP, respectively. The doses to the bone marrow were 2.5±0.4 mGy/MBq for90Y- citrate and 1.8±0.6 mGy/MBq for90Y-EDTMP.86Y and PET provide quantitative information applicable to the clinical use of90Y. This method may also be useful for the design of other90Y radiopharmaceuticals and for planning radiotherapy dosages. 相似文献
86.
87.
Kurt Krejcy Gunther Krumpl Hannes Todt Gerhard Raberger 《Naunyn-Schmiedeberg's archives of pharmacology》1992,346(2):213-218
Summary The aim of the present study was to investigate the dose-dependent antiarrhythmic efficacy of lidocaine against electrically induced tachycardias in conscious, chronically instrumented postinfarction dogs. Programmed electrical stimulation (PES) was performed in 16 dogs 8 to 21 days after a 4 h occlusion of the left anterior descending coronary artery (LAD). Infusion of saline in 8 control animals with sustained ventricular tachycardia (SVT) inducible at baseline did not affect subsequent inducibility. In the treatment group 7 of 8 animals responded with SVT and one exhibited ventricular fibrillation at baseline. After an initial bolus of 1 mg/kg lidocaine intravenously (i.v.), the drug was infused at infusion rates of 40, 80 and 120 g/kg/min (i.v.). During 80 g/kg/min lidocaine (mean plasma level 3.5 g/ml) 7 out of 8 animals displayed an antiarrhythmic response; both the lower and the higher infusion rate were associated with a smaller antiarrhythmic efficacy (3 of 8 animals responded to 40 g/kg/min and 4 of 8 to 120 g/kg/min). Licocaine did not affect ventricular refractory periods, but induced an increase in intraventricular conduction time at all infusion rates, from 66.2 ms at baseline to 67.7 ms (p<0.05), 67.7 ms (p<0.05), 70.0 ms (p<0.01) respectively.In conclusion the present study demonstrates that lidocaine is of considerable value in the management of PES-induced ventricular arrhythmias in the postinfarction phase. However there is only a small optimal therapeutic plasma level range, where lidocaine exhibits its antiarrhythmic efficacy against this type of arrhythmia; this makes a carefully titration of the drug necessary both in the experimental and in the clinical setting.
Send offprint requests to K. Krejcy at the above address 相似文献
88.
Specific chromosomal losses have been reported for various human tumors. We have now investigated ten cases of urothelial carcinoma and observed genomic alterations by a new method allowing detection of chromosomal losses directly in the tissue section. In 6 out of 8 male carcinomas, the Y-chromosome was lost either in single cells and isolated areas or in extended regions of the tumor sample. Presence of chromosome 1 served as an internal control. This new in situ method allows studies of chromosomal alterations in relation to their tumor topology and the observations constitute the first report on such localised tumor-specific genomic changes. 相似文献
89.
Hans Christian Blossey Hans Helge Bartsch Dietrich Kanne Johannes Koebberling Gerhard Arno Nagel 《Cancer chemotherapy and pharmacology》1982,8(1):77-81
Summary Oral MPA 1.5 g/day leads to plasma concentrations between 1 and 12 g/ml, with a broad intra-and interindividual variance. The plateau state is reached in between 4 and 16 days. Plasma concentrations in the plateau state are very sensitive to dose modifications. After cessation of administration, the decline in plasma levels seems to proceed in two phases, with half-times of about 20 h and 4 days. Extraction procedures reveal no benefit in discriminating between MPA and its metabolites. 相似文献
90.
Gerhard Kloss Margret Leven 《European journal of nuclear medicine and molecular imaging》1979,4(3):179-186
Because tyrosine and dopa can be regarded as precursors of adrenomedullary hormones and melanin, radioiodinated derivatives of these compounds were tested for their accumulation in the adrenal medulla and in melanomas of various animal species. The highest level of accumulation in the adrenal medulla was attained in mice and rats with iodinated -hydroxy--methyltyramine, and in melanomas of mice with iodinated -methyltyrosine. The results could not be reproduced to the same extent in other species. 相似文献