全文获取类型
收费全文 | 10989篇 |
免费 | 834篇 |
国内免费 | 38篇 |
专业分类
耳鼻咽喉 | 80篇 |
儿科学 | 333篇 |
妇产科学 | 316篇 |
基础医学 | 1439篇 |
口腔科学 | 250篇 |
临床医学 | 1361篇 |
内科学 | 2144篇 |
皮肤病学 | 264篇 |
神经病学 | 1117篇 |
特种医学 | 210篇 |
外科学 | 1190篇 |
综合类 | 73篇 |
一般理论 | 16篇 |
预防医学 | 1352篇 |
眼科学 | 191篇 |
药学 | 735篇 |
中国医学 | 32篇 |
肿瘤学 | 758篇 |
出版年
2023年 | 133篇 |
2022年 | 228篇 |
2021年 | 465篇 |
2020年 | 265篇 |
2019年 | 364篇 |
2018年 | 382篇 |
2017年 | 274篇 |
2016年 | 315篇 |
2015年 | 323篇 |
2014年 | 401篇 |
2013年 | 593篇 |
2012年 | 860篇 |
2011年 | 842篇 |
2010年 | 488篇 |
2009年 | 384篇 |
2008年 | 656篇 |
2007年 | 643篇 |
2006年 | 591篇 |
2005年 | 569篇 |
2004年 | 481篇 |
2003年 | 461篇 |
2002年 | 429篇 |
2001年 | 63篇 |
2000年 | 50篇 |
1999年 | 53篇 |
1998年 | 74篇 |
1997年 | 72篇 |
1996年 | 66篇 |
1995年 | 58篇 |
1994年 | 43篇 |
1993年 | 51篇 |
1992年 | 55篇 |
1991年 | 50篇 |
1990年 | 49篇 |
1989年 | 52篇 |
1988年 | 61篇 |
1987年 | 65篇 |
1986年 | 60篇 |
1985年 | 47篇 |
1984年 | 56篇 |
1983年 | 57篇 |
1982年 | 45篇 |
1981年 | 43篇 |
1980年 | 46篇 |
1979年 | 35篇 |
1978年 | 31篇 |
1977年 | 31篇 |
1975年 | 24篇 |
1974年 | 25篇 |
1973年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
C. Edwin Polk DDS MSD David Buchanan PhD 《American journal of orthodontics and dentofacial orthopedics》2003,124(6):663-669
The cephalometric measurement known as Wits appraisal (AOBO) was studied to determine its importance in diagnosis, treatment, and prediction of treatment success. The Wits appraisal is used primarily to identify unreliable ANB values (those that do not accurately reflect the degree of horizontal jaw discrepancy, ie, those that differ greatly from the AOBO value). Therefore, differences between AOBO and ANB also were evaluated. Because neither measurement alone can assess jaw discrepancies with total accuracy, they were combined, plotted on a scattergram, and divided into equal zones to create a new index of horizontal skeletal discrepancies and treatment predictability. Pretreatment values correspond to treatment difficulty, and posttreatment values correspond to the effectiveness of treatment. Treatment time for each zone also was evaluated. We were able to draw several conclusions from this study. First, combining AOBO and ANB values results in a more accurate measurement of treatment difficulty. These combined values also can be used to predict both treatment time and the success of treatment for horizontal discrepancies. Second, the AOBO value predicts variations in treatment time at each ANB value. Finally, adding ANB and AOBO values and then dividing the total yields zones that represent statistically significant differences in treatment times and percentages of success. The zones also correlate with the difference between AOBO and ANB measurements. 相似文献
2.
L C Harlan B F Polk S Cooper T P Blaszkowski J Ignatius-Smith M Stromer H Mull 《American journal of preventive medicine》1986,2(5):256-261
The effects of labeling a person as hypertensive have important implications for hypertension screening. The Hypertension Detection and Follow-up Program (HDFP) provides an opportunity to examine the effects of labeling, treatment, and study assignment on a large group of hypertensives (n = 10,070). Their answers to questions regarding perceived health and general well-being asked at baseline and again one year later were analyzed. There was no significant change in the perceived health status of persons who were unaware of their hypertension at baseline and remained untreated at one year (labeling alone). The effect of labeling plus treatment was associated with a significant decrease in perceived health. The effect of antihypertensive drug therapy on perceived health status was examined in persons who were aware of their hypertension but not on treatment at baseline, and on treatment at one year. The stepped care group (SC) had a significant improvement in their perceived health and a significant decrease in the amount of time spent worrying about their health. The referred care group (RC) had no change. Program assignment effects were studied in individuals aware of their hypertension and on treatment both at baseline and one year later. Both the SC and RC groups had a significant improvement in their perceptions of their health status. The SC group had a significant decrease in time spent worrying about their health, while the RC group showed no change. These reassuring results fail to support the suggestion that labeling persons as hypertensive is necessarily followed by negative psychological consequences.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
3.
Robert H. EckelAuthor Vitae Penny Kris-EthertonAuthor Vitae Alice H. LichtensteinAuthor Vitae Judith Wylie-RosettAuthor Vitae Allison Groom Author Vitae Kimberly F. StitzelAuthor Vitae Shirley Yin-PiazzaAuthor Vitae 《Journal of the American Dietetic Association》2009,109(2):288-296
In recent years, epidemiologic and clinical studies, public and regulatory policy activity, and media coverage have focused on issues related to trans fats. To help increase awareness and understanding of trans fats and other fats, the American Heart Association (AHA) launched the “Face the Fats” national consumer education campaign in April 2007. The AHA commissioned a quantitative tracking survey between 2006 and 2007 to measure changes in consumer awareness, knowledge, and behaviors related fats and oils and their perceived impact on heart disease. The survey was conducted by Cogent Research. Data were collected during March 2006 and May 2007. At both time points, the survey included a representative sample of the American population age 18 to 65 years (n=1,000). The sampling plan for the survey was designed based on the 2000 and 2003 US Census. The margin of error was ±3.10 percentage points. Awareness of trans fats increased during the 1-year study period. In 2007, 92% of respondents were aware of trans fats, an increase from 84% in 2006 (P<0.05). The 2007 level was similar to the awareness of saturated fats (93%). Perceptions that certain fats and oils heighten the risk of heart disease increased for trans fats (73% in 2007 vs 63% in 2006; P<0.05), saturated fats (77% in 2007 vs 73% in 2006; P<0.05), and partially hydrogenated oils (56% in 2007 vs 49% in 2006; P<0.05). Knowledge about food sources of different fats remained low. On an unaided basis, 21% could name three food sources of trans fats in 2007, up from 17% in 2006 (P<0.05). Knowledge of food sources of saturated fat remained unchanged at 30% in 2007. Significantly more respondents in 2007 reported behavioral changes related to trans fat information, such as buying food products because they show “zero trans fat” on labels or packages (37% in 2007 vs. 32% in 2006; P<0.05). Between 2006 and 2007, consumer awareness about trans fats increased and attained awareness levels similar to saturated fats. The increased awareness is associated with improved self-reported behaviors in grocery shopping. Nonetheless, overall knowledge, especially regarding food sources of saturated and trans fats, remains relatively low, underscoring the need for heightened consumer education activities. The positive change in consumer awareness about trans fats is likely attributable to the wide range of messages available to them, including the AHA “Face the Fats” national consumer education campaign. 相似文献
4.
5.
6.
Rosa M. Razaboni M. Alba Greco Alice D. Harper William W. Shaw Donald L. Ballantyne 《Microsurgery》1981,3(2):65-71
Segments 15 mm in length were excised from the femoral veins of rats and preserved by refrigeration at 4 C in lactated Ringer's solution for periods up to 21 days. The findings show that veins can be preserved for up to seven days and successfully grafted to recipients. Although there was some success in preserving vein segments for more than seven days, a high rate of thrombosis occurred after implantation in the recipients. It is generally accepted that damaged endothelium causes thrombosis. The light and electron microscopic observations in this study, however, suggest that the condition of the endothelium may not be the only important factor in the patency of small vessels. A thickened and prominent elastic lamina may also play a role in keeping the lumen open. 相似文献
7.
8.
9.
Li Li Alice C Jiang Pin Dong Yi Wan Zi Wei Yu 《Otolaryngology--head and neck surgery》2007,137(4):659-664
OBJECTIVE: To investigate the characteristics of Hep-2 cell with multidrug resistance (MDR) induced by Taxol. STUDY DESIGN: Hep-2 cells were exposed in stepwise escalating concentration of Taxol to develop the resistant cell line-Hep-2T. Cell cycle distribution, apoptosis, and rhodamine accumulation were studied through flow cytometry. The MDR1 and MRP1 genes were detected through real-time quantitative RT-PCR, and the corresponding proteins were detected through Western blotting. RESULTS: The drug resistance of Hep-2T cells to Taxol, doxorubicin, gemcitabine, 5-FU, and cisplatin all increased. The percentage of G0/G1 phase and the antiapoptosis ability increased significantly compared with Hep-2 cells. Both MDR1 and MRP1 also increased at gene and protein level, though MDR1 was more prominent. CONCLUSION: More emphasis should be laid on MDR1/Pgp, the non-Pgp substrate chemotherapeutic agents, and the changes of cell cycle distribution to prevent MDR induced by Taxol. SIGNIFICANCE: These findings may provide theoretical support for the reverse of MDR. 相似文献
10.
Empty Sella and Headache 总被引:2,自引:0,他引:2
Teresa Catarci Fabrizio Fiacco Luigi Bozzao Manuela Pati Alice Valeria Magiar Rosanna Cerbo 《Headache》1994,34(10):583-586
SYNOPSIS
Empty sella is an anatomical condition caused by herniation of the subarachnoid space into the pituitary fossa through an incompetent seller diaphragm. Headache seems to be one of the most frequently reported symptoms. We studied 13 headache patients (12 females, 1 male) presenting with primary empty sella (PES) on CT scan. The characteristics of the headache were analyzed and plasma levels of pituitary hormones or cortisol assessed. We confirmed the nonspecific nature of the headache in PES even though the majority of our patients complained of daily headache, mostly localized anteriorly. Hormone plasma levels were within normal range in all the patients assessed. However, four patients reported earlier endocrine disorders and more than half of the patients presented with obesity.
In our opinion, PES should be suspected in middle-aged overweight women with daily headache even in the absence of endocrine symptomatology. 相似文献
Empty sella is an anatomical condition caused by herniation of the subarachnoid space into the pituitary fossa through an incompetent seller diaphragm. Headache seems to be one of the most frequently reported symptoms. We studied 13 headache patients (12 females, 1 male) presenting with primary empty sella (PES) on CT scan. The characteristics of the headache were analyzed and plasma levels of pituitary hormones or cortisol assessed. We confirmed the nonspecific nature of the headache in PES even though the majority of our patients complained of daily headache, mostly localized anteriorly. Hormone plasma levels were within normal range in all the patients assessed. However, four patients reported earlier endocrine disorders and more than half of the patients presented with obesity.
In our opinion, PES should be suspected in middle-aged overweight women with daily headache even in the absence of endocrine symptomatology. 相似文献