全文获取类型
收费全文 | 4291篇 |
免费 | 263篇 |
国内免费 | 23篇 |
专业分类
耳鼻咽喉 | 43篇 |
儿科学 | 153篇 |
妇产科学 | 121篇 |
基础医学 | 533篇 |
口腔科学 | 106篇 |
临床医学 | 395篇 |
内科学 | 933篇 |
皮肤病学 | 68篇 |
神经病学 | 417篇 |
特种医学 | 203篇 |
外科学 | 491篇 |
综合类 | 22篇 |
一般理论 | 1篇 |
预防医学 | 362篇 |
眼科学 | 62篇 |
药学 | 297篇 |
中国医学 | 10篇 |
肿瘤学 | 360篇 |
出版年
2024年 | 6篇 |
2023年 | 35篇 |
2022年 | 74篇 |
2021年 | 140篇 |
2020年 | 109篇 |
2019年 | 127篇 |
2018年 | 122篇 |
2017年 | 94篇 |
2016年 | 126篇 |
2015年 | 128篇 |
2014年 | 181篇 |
2013年 | 233篇 |
2012年 | 372篇 |
2011年 | 404篇 |
2010年 | 182篇 |
2009年 | 158篇 |
2008年 | 298篇 |
2007年 | 316篇 |
2006年 | 277篇 |
2005年 | 281篇 |
2004年 | 247篇 |
2003年 | 209篇 |
2002年 | 166篇 |
2001年 | 37篇 |
2000年 | 33篇 |
1999年 | 29篇 |
1998年 | 27篇 |
1997年 | 24篇 |
1996年 | 8篇 |
1995年 | 13篇 |
1994年 | 20篇 |
1993年 | 10篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1972年 | 2篇 |
1971年 | 4篇 |
1969年 | 7篇 |
1968年 | 4篇 |
排序方式: 共有4577条查询结果,搜索用时 31 毫秒
101.
102.
103.
104.
Elina Sillanpää Arja Häkkinen Keijo Häkkinen 《European journal of applied physiology》2013,113(9):2331-2341
Purpose
Few studies have examined responsiveness of bioimpedance (BIA) to detect changes over time in body composition using a longitudinal design. Accuracy of BIA and skinfold thickness in estimating body composition among 39–64 year-old women was investigated using dual-energy X-ray absorptiometry (DXA) as a criterion method both cross-sectionally and during a training intervention.Methods
97 women had percentage of fat assessed using DXA, skinfolds and eight-polar BIA using multi-frequency current. Fat mass and lean mass were estimated by DXA and BIA. Measurements were performed before and after the 21-week training intervention.Results
At baseline relative to DXA, BIA under predicted percentage of fat (?6.50 %) and fat mass (?3.42 kg) and overestimated lean mass (3.18 kg) considerably. Also skinfold measurement under predicted percentage of fat compared to DXA, but the difference was smaller (?1.69 % units). Skinfold measurement overestimated percentage of fat at low values and underestimated at high values (r 2 = 0.535). A significant bias was detected between DXA and BIA’s estimate of change in percentage of fat, fat mass and lean mass. Compared to DXA, BIA and skinfolds underestimated the training-induced positive changes in body composition.Conclusions
BIA and skinfold methods compared to DXA are not interchangeable to quantify the percentage of fat, fat mass and lean mass at the cross-sectional design in middle-aged women. Moreover, exercise training-induced small changes in body composition cannot be detected with BIA or skinfold method, even though DXA was able to measure statistically significant within-group changes in body composition after training. 相似文献105.
106.
Reina Matsui Takeshi Hagino Nelson Hirokazu Tsuno Hideo Ohtani Fumihiro Azuma Mika Matsuhashi Makoto Saito Maya Kobayashi Reina Saga Hiroko Hidai Hisashi Tsutsumi Hideki Akiyama Sayuri Motomura 《Transfusion and apheresis science》2021,60(3):103123
The measurement of corrected count increment at 1-h post-transfusion (CCI-1 h) of platelet concentrate (PC) transfusion is recommended, but in the revised Japanese Guideline (2017) it was changed to “after 10-min to 1-h”, following the revision of the guidelines from Western countries. Here, we aimed to investigate on the feasibility to apply the CCI measured at 10-min or 30-min post-transfusion as the surrogate of CCI-1 h. Peripheral blood was collected at 10-min, 30-min and 1-h post-transfusion of PC and the effectiveness of the transfusion was analyzed based on the CCI. In the period from December 2017 to February 2020, 8 patients, who received multiple PC transfusion (total 208) at our institution, were analyzed. We performed the univariate analyses to examine the relationship between CCI value and the categorical variables, p-value <0.1 was obtained for gender (p = 2.91 × 10?19), fever after transfusion (p = 0.0163). The qualitative variables, namely measurement time (p = 0.0553), also showed p-value <0.1. Using these factors as covariates in the mixed effect model, we found that the measurement time (p = 0.0007) had a significant effect on the CCI value when looking at fixed effects. Although there is a tendency for decreased CCI values with time progression, the slope of the change in the mixed model was -0.00307, indicating that the CCI difference among the 3 measurements was small. Here we provide evidence that CCI measured at 10-min and 30-min post-transfusion give results comparable to those measured at 1-h post-transfusion, under the Japanese practice of platelet transfusion, which relies on 100 % single-donor apheresis PC, and ABO-identical whenever possible. 相似文献
107.
Converting from CT- to MRI-only-based target definition in radiotherapy of localized prostate cancer
108.
109.
110.
Retardation of skeletal development and cervical abnormalities in transgenic mice expressing a dominant-negative retinoic acid receptor in chondrogenic cells
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Masahiro Yamaguchi Mika Nakamoto Hiroaki Honda Toshiyuki Nakagawa Hiroshi Fujita Takashi Nakamura Hisamaru Hirai Shuh Narumiya Akira Kakizuka 《Proceedings of the National Academy of Sciences of the United States of America》1998,95(13):7491-7496
Skeletal formation is a fundamental element of body patterning and is strictly regulated both temporally and spatially by a variety of molecules. Among these, retinoic acid (RA) has been shown to be involved in normal skeletal development. However, its pleiotropic effects have caused difficulty in identifying its crucial target cells and molecular mechanisms for each effect. Development of cartilage primordia is an important process in defining the skeletal structures. To address the role of RA in skeletal formation, we have generated mice expressing a dominant-negative retinoic acid receptor (RAR) in chondrogenic cells by using the type II collagen α1 promoter, and we have analyzed their phenotypes. These mice exhibited small cartilage primordia during development and retarded skeletal formation in both embryonic and postnatal periods. They also showed selective degeneration in their cervical vertebrae combined with homeotic transformations, but not in their extremities. The cervical phenotypes are reminiscent of phenotypes involving homeobox genes. We found that the expression of Hoxa-4 was indeed reduced in the cartilage primordia of cervical vertebrae of embryonic day 12.5 embryos. These observations demonstrate that endogenous RA acts directly on chondrogenic cells to promote skeletal growth in both embryonic and growing periods, and it regulates the proper formation of cervical vertebrae. Furthermore, RA apparently specifies the identities of the cervical vertebrae through the regulation of homeobox genes in the chondrogenic cells. Great similarities of the phenotypes between our mice and reported RAR knockout mice revealed that chondrogenic cells are a principal RA target during complex cascades of skeletal development. 相似文献