全文获取类型
收费全文 | 17554篇 |
免费 | 1415篇 |
国内免费 | 53篇 |
专业分类
耳鼻咽喉 | 194篇 |
儿科学 | 611篇 |
妇产科学 | 325篇 |
基础医学 | 2875篇 |
口腔科学 | 414篇 |
临床医学 | 1739篇 |
内科学 | 3682篇 |
皮肤病学 | 340篇 |
神经病学 | 1458篇 |
特种医学 | 564篇 |
外国民族医学 | 1篇 |
外科学 | 2289篇 |
综合类 | 108篇 |
一般理论 | 9篇 |
预防医学 | 1317篇 |
眼科学 | 367篇 |
药学 | 1435篇 |
中国医学 | 20篇 |
肿瘤学 | 1274篇 |
出版年
2023年 | 97篇 |
2022年 | 128篇 |
2021年 | 288篇 |
2020年 | 249篇 |
2019年 | 318篇 |
2018年 | 326篇 |
2017年 | 317篇 |
2016年 | 377篇 |
2015年 | 359篇 |
2014年 | 509篇 |
2013年 | 679篇 |
2012年 | 976篇 |
2011年 | 911篇 |
2010年 | 517篇 |
2009年 | 512篇 |
2008年 | 794篇 |
2007年 | 834篇 |
2006年 | 797篇 |
2005年 | 803篇 |
2004年 | 852篇 |
2003年 | 704篇 |
2002年 | 646篇 |
2001年 | 456篇 |
2000年 | 500篇 |
1999年 | 443篇 |
1998年 | 242篇 |
1997年 | 166篇 |
1996年 | 189篇 |
1995年 | 161篇 |
1994年 | 145篇 |
1993年 | 146篇 |
1992年 | 321篇 |
1991年 | 345篇 |
1990年 | 335篇 |
1989年 | 346篇 |
1988年 | 263篇 |
1987年 | 279篇 |
1986年 | 239篇 |
1985年 | 290篇 |
1984年 | 192篇 |
1983年 | 164篇 |
1982年 | 128篇 |
1981年 | 101篇 |
1980年 | 90篇 |
1979年 | 165篇 |
1978年 | 122篇 |
1977年 | 106篇 |
1975年 | 97篇 |
1974年 | 117篇 |
1973年 | 105篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
1.
Martin R. Späth Malte P. Bartram Nicolàs Palacio-Escat K. Johanna R. Hoyer Cedric Debes Fatih Demir Christina B. Schroeter Amrei M. Mandel Franziska Grundmann Giuliano Ciarimboli Andreas Beyer Jayachandran N. Kizhakkedathu Susanne Brodesser Heike Göbel Jan U. Becker Thomas Benzing Bernhard Schermer Martin Höhne Markus M. Rinschen 《Kidney international》2019,95(2):333-349
2.
Christian Holm Hansen Shelley Lees Saidi Kapiga Janet Seeley Tony Barnett 《Global public health》2020,15(3):402-413
ABSTRACTMeasuring hope reliably and accurately remains an important research objective, not least in less prosperous settings where ‘holding on to hope’ may be critically important in the struggle against adverse life conditions. The State Hope Scale was designed for use in the US. Despite reported application in diverse cultures and using translations the scale has not been extensively validated outside US populations. This study contributes to a larger project exploring the measurement of hope and provides a critique of Snyder’s scale as used in a Tanzanian female population of 1021 urban microfinance participants. We evaluate the scale’s validity through assessment of the empirical distribution of scores, item response profiles, internal consistency and discriminatory ability. Participants mostly scored very high and many reached very near the maximum attainable score. Hardly any endorsed the negative half of the response scale. Several problems are discussed including poor discrimination and strong evidence of acquiescence response bias. We also found little association of the scale scores with hypothesised correlates of hope. Future improvements on the measurement of hope are recommended, especially in studies outside the narrow Western context in which the scale was devised. 相似文献
3.
4.
5.
6.
Non‐melanoma skin cancer frequently results from chronic exposure to ultraviolet (UV) irradiation. UV‐induced DNA damage activates cell cycle arrest checkpoints through degradation of the cyclin‐dependent kinase activators, the cell division cycle 25 (CDC25) phosphatases. We previously reported increased CDC25A in nonmelanoma skin cancer, but CDC25B and CDC25C had not been previously examined. Consequently, we hypothesized that increased expression of CDC25B and CDC25C increases tumor cell proliferation and skin tumor growth. We found that CDC25B and CDC25C were increased in mouse and human skin cancers. CDC25B was primarily cytoplasmic in skin and skin tumors and was significantly increased in the squamous cell carcinoma (SCC), while CDC25C was mostly nuclear in the skin, with an increased cytoplasmic signal in the premalignant and malignant tumors. Surprisingly, forced expression of CDC25B or CDC25C in cultured SCC cells did not affect proliferation, but instead suppressed apoptosis, while CDC25C silencing increased apoptosis without impacting proliferation. Targeting CDC25C to the nucleus via mutation of its nuclear export sequence, however, increased proliferation in SCC cells. Overexpression of CDC25C in the nuclear compartment did not hinder the ability of CDC25C to suppress apoptosis, neither did mutation of sites necessary for its interaction with 14‐3‐3 proteins. Analysis of apoptotic signaling pathways revealed that CDC25C increased activating phosphorylation of Akt on Ser473, increased inhibitory phosphorylation of proapoptotic BAD on Ser136, and increased the survival protein Survivin. Silencing of CDC25C significantly reduced Survivin levels. Taken together, these data suggest that increased expression of CDC25B or CDC25C are mechanisms by which skin cancers evade apoptotic cell death. 相似文献
7.
背景:对于脊椎以外的骨折而言,补充口服维生素D的预防作用和用量仍无定论。
目的:评估补充维生素D在预防老年髋骨骨折和非脊椎骨折方面的效果。
数据来源:使用MEDLINE、Cochrance对照试验记录(1960~2005年)以及EMBASE(1991-2005年),对英文和非英文文章进行系统回顾。通过与临床专家接触,通过检索美国社会骨和骨矿研究协会提供的参考文献和摘要(1995~2004年).进一步寻找更多的研究。检索词包括随机对照试验(randomized controlled trial,RCT)、临床对照试验、随机分配、双盲法、维生素D3、维生素D2;25-羟基维生素D、骨折、人类、老年、摔倒和骨密度。
研究选取:纳入的研究仅限于口服补充维生素D(维生素D3、维生素D2、补钙或不补钙)与补钙或安慰剂比较的双盲RCTs。试验于检查髋部骨折或非脊椎骨折的老年人(年龄≥60岁)中进行。数据提取:两位作者根据预先规定独立提取相关数据,其中包括研究质量指标。
数据综合:所有的汇总分析均以随机效应模型为基础。5项有关髋部骨折的RCTs(n=9294)和7项有关非脊椎骨折危险的RCTs(n=9820)符合我们的纳入标准。所有试验均使用了维生素D3。对髋部和非脊椎骨折预防研究的异质性亦进行观察,用低剂量(400IU/d)和高剂量(700~800IU/d)分别合并RCTs后异质性消失。与补钙或安慰剂相比,每天服700~800IU的维生素D可使髋部骨折的相对危险(relative risk,aa)下降26%(3项RCTs共计5572人;RR,0.74;95%可信区间[confidence interval,CI],0.61~0.88),使非脊椎骨折的相对危险下降23%(5项RCTs共计6098人;RR,0.77;95%CI,0.68~0.87)。每天服400IU的维生素D(2项RCTs共计3722人;髋部骨折RR,1.15;95%CI,0.88~1.50;非脊椎骨折RR,1.03;95%CI,0.86—1.24)未见明显获益。
结论:口服补充维生素D(700~800IU/d)可以降低尚能活动的老人或慈善机构收容的老年人发生髋部骨折和脊椎以外骨折的危险,每天口服400IU维生素D并不足以预防骨折。 相似文献
8.
9.
Clinical versus ultrasonographic evaluation of scrotal disorders 总被引:1,自引:0,他引:1
B Kromann-Andersen L B Hansen P N Larsen K Lawetz P Lynge D Lysen S P Nielsen K H Stockholm P Foged 《British journal of urology》1988,61(4):350-353
Clinical and ultrasonographic examinations of scrotal disorders were compared in 166 patients in order to determine their ability to distinguish between those diseases requiring surgery and those requiring clinical follow-up only. Ultrasound examinations were efficient in discriminating between normal and pathological findings. Extra-testicular lesions were readily differentiated from testicular ones. Although both clinical and ultrasonographic examinations had high sensitivity (90%) in detecting testicular cancer, the number of false positive findings was smaller after ultrasound examination. This gave a predictive value of a positive test of 53% after ultrasound examination but only 33% after clinical examination. Ultrasound examination may, therefore, reduce the number of surgical explorations in the scrotum and should be performed in patients with suspected testicular pathology based on history and palpatory findings. 相似文献
10.