全文获取类型
收费全文 | 28359篇 |
免费 | 6319篇 |
国内免费 | 170篇 |
专业分类
耳鼻咽喉 | 704篇 |
儿科学 | 803篇 |
妇产科学 | 873篇 |
基础医学 | 1376篇 |
口腔科学 | 2965篇 |
临床医学 | 4746篇 |
内科学 | 6323篇 |
皮肤病学 | 574篇 |
神经病学 | 2578篇 |
特种医学 | 1487篇 |
外科学 | 4880篇 |
综合类 | 90篇 |
现状与发展 | 12篇 |
一般理论 | 2篇 |
预防医学 | 3081篇 |
眼科学 | 526篇 |
药学 | 710篇 |
中国医学 | 20篇 |
肿瘤学 | 3098篇 |
出版年
2024年 | 167篇 |
2023年 | 1132篇 |
2022年 | 466篇 |
2021年 | 836篇 |
2020年 | 1356篇 |
2019年 | 647篇 |
2018年 | 1500篇 |
2017年 | 1445篇 |
2016年 | 1720篇 |
2015年 | 1803篇 |
2014年 | 2261篇 |
2013年 | 2810篇 |
2012年 | 1329篇 |
2011年 | 1287篇 |
2010年 | 1691篇 |
2009年 | 2240篇 |
2008年 | 1229篇 |
2007年 | 968篇 |
2006年 | 1068篇 |
2005年 | 855篇 |
2004年 | 672篇 |
2003年 | 628篇 |
2002年 | 578篇 |
2001年 | 439篇 |
2000年 | 316篇 |
1999年 | 435篇 |
1998年 | 555篇 |
1997年 | 519篇 |
1996年 | 584篇 |
1995年 | 437篇 |
1994年 | 342篇 |
1993年 | 290篇 |
1992年 | 208篇 |
1991年 | 180篇 |
1990年 | 157篇 |
1989年 | 164篇 |
1988年 | 140篇 |
1987年 | 151篇 |
1986年 | 121篇 |
1985年 | 124篇 |
1984年 | 107篇 |
1983年 | 110篇 |
1982年 | 109篇 |
1981年 | 85篇 |
1980年 | 66篇 |
1979年 | 46篇 |
1978年 | 47篇 |
1977年 | 59篇 |
1976年 | 41篇 |
1974年 | 41篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
Antihypertensive Combination Therapy: Optimizing Blood Pressure Control and Cardiovascular Risk Reduction 总被引:1,自引:0,他引:1
Treating hypertension reduces the rates of myocardial infarction, stroke, and renal disease; however, clinical trial experience suggests that monotherapy is not likely to be successful for achieving goal blood pressure (BP) levels in many hypertensive patients. In multiple recent clinical trials including various subsets of hypertensive patients, the achievement of BP goal has typically required the combination of 2 or more medications, particularly in patients with BP levels >160/100 mm Hg. When initiating combination therapy for hypertension, careful consideration must be given to the choice of medication. Clinical trial evidence has shown the efficacy of various combinations of angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, calcium channel blockers, and diuretics in reducing BP and cardiovascular risk. Ongoing trials should provide additional guidance on the optimal choice of combination regimens in specific clinical settings. 相似文献
43.
Color Stability of Dry Earth Pigmented Maxillofacial Silicone A-2186 Subjected to Microwave Energy Exposure 总被引:2,自引:0,他引:2
Sudarat Kiat-amnuay DDS MS ; Dennis A. Johnston PhD ; John M. Powers PhD ; Rhonda F. Jacob DDS MS 《Journal of prosthodontics》2005,14(2):91-96
PURPOSE: The purpose of this study was to measure spectrophotometrically the color stability of pigmented A-2186 silicone maxillofacial elastomer with 10% by volume of titanium white dry earth opacifier before and after exposure to microwave energy over a simulated 1.5-year period of microwave sterilization. Materials AND METHODS: A-2186 silicone elastomer opacified with titanium white dry earth pigment, pigmented with 5 cosmetic dry earth pigment colors [no pigment (control) group (Pc), red (Pr), yellow ochre (Py), burnt sienna (Po), and a mixture of Pr + Py + Po color group (P3)], was used in this study. Each of the 5 experimental groups consisted of 5 specimens. All specimens were placed in a 250 ml glass beaker filled with 150 ml of water (replenished for each microwave exposure). An exposure of 6 minutes was used 18 times (simulating 1.5 years of microwave sterilization with one 6 minute exposure monthly). Reflectance values were measured by spectrophotometer. Three- and two-way analyses of variance with repeated measures were performed for the color difference (DeltaE*) with the factors of group/color/months, and group/months, respectively. Means were compared by Tukey Honest Significant Difference (HSD) multiple range test calculated at the 0.05 level of significance using SPSS. RESULTS: The trained human eye can detect color changes (DeltaE*) greater than 1.0. Most DeltaE* values of the red pigment group at all intervals and the mixed pigment group at 15- and 18- month intervals increased significantly greater than 1.0 (p < 0.001) compared with the control group. Yellow and burnt sienna groups remained the most color stable over time with DeltaE* values below 0.35. CONCLUSIONS: Lack of color stability of red dry earth pigmented A-2186 silicone maxillofacial elastomers was clinically significant after 12-month exposure to microwave energy as compared with yellow, burnt sienna, and opacified A-2186 dry earth pigments. 相似文献
44.
The study explored the counterfactual thinking that women with chronic and widespread pain showed in response to what they themselves considered to be particularly stressful situations. Counterfactual thinking in 125 women sick‐listed due to chronic and widespread pain was investigated in terms of structure, function and control focus. The women were asked, for each of three types of problems that they indicated in a questionnaire to affect them most strongly, to describe a typical occurrence of it and to complete a counterfactual sentence in connection with it of the type ‘If only . . .’. The majority of counterfactuals pertained to predominantly somatic problems (e.g. musculo‐skeletal problems, pain and fatigue) classified as being affective rather than preparative and self‐focused rather than external, whereas in counterfactuals relating to predominantly psychological/psychosocial problems a preparative function and an external focus were more prominent. The numbers of problems listed and the numbers of situations responded to counterfactually were positively correlated. The counterfactuals, although often related to somatic problems, generally concerned psychological or psychosocial matters such as finances and paid or unpaid work. A contextual approach to elucidating counterfactual thinking based on subjects' own experiences is seen as providing valuable insight into what bothers them most. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
45.
46.
47.
48.
49.
Robert P. Kusy BS MS PhD 《American journal of orthodontics and dentofacial orthopedics》2004,125(6):726-732
Using an earlier model, which described the critical contact angle for binding from second-order angulation alone, a more generalized model is derived that combines the effects of angulation and torque. From this vantage point, the onset of binding is evaluated for 3 scenarios: second-order angulation alone, third-order torque only, and a combination of second-order angulation and third-order torque. These scenarios are detailed by plotting the critical contact angle for binding against the torque angle as a function of 10 wire dimensions (16 x 16, 16 x 22, 17 x 17, 17 x 22, 17 x 25, 18 x 18, 18 x 22, 18 x 25, 19 x 25, and 21 x 25 mil), 4 bracket widths (70, 100, 130, and 160 mil), and 4 bracket slots (18, 20.5, 22, and 24.5 mil). From these plots, we learn that each wire base dimension (eg, an 18-mil base as found in 18 x 18-mil, 18 x 22-mil and 18 x 25-mil archwires) has a common maximum critical contact angle for binding. Moreover, each wire-slot combination has a common maximum torque angle, which is independent of bracket width. Finally, we learn that archwire-bracket combinations that use a metric 0.5-mm slot might have some advantages with regard to torquing--given the current philosophy that light, continuous forces are more favorable. 相似文献
50.