全文获取类型
收费全文 | 1699篇 |
免费 | 100篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 43篇 |
妇产科学 | 53篇 |
基础医学 | 116篇 |
口腔科学 | 47篇 |
临床医学 | 194篇 |
内科学 | 720篇 |
皮肤病学 | 16篇 |
神经病学 | 137篇 |
特种医学 | 228篇 |
外科学 | 66篇 |
综合类 | 18篇 |
预防医学 | 38篇 |
眼科学 | 17篇 |
药学 | 52篇 |
中国医学 | 1篇 |
肿瘤学 | 55篇 |
出版年
2023年 | 6篇 |
2022年 | 5篇 |
2021年 | 17篇 |
2020年 | 13篇 |
2019年 | 12篇 |
2018年 | 24篇 |
2017年 | 18篇 |
2016年 | 20篇 |
2015年 | 18篇 |
2014年 | 47篇 |
2013年 | 62篇 |
2012年 | 66篇 |
2011年 | 56篇 |
2010年 | 62篇 |
2009年 | 56篇 |
2008年 | 57篇 |
2007年 | 60篇 |
2006年 | 52篇 |
2005年 | 41篇 |
2004年 | 54篇 |
2003年 | 43篇 |
2002年 | 44篇 |
2001年 | 33篇 |
2000年 | 44篇 |
1999年 | 36篇 |
1998年 | 65篇 |
1997年 | 63篇 |
1996年 | 57篇 |
1995年 | 54篇 |
1994年 | 55篇 |
1993年 | 41篇 |
1992年 | 54篇 |
1991年 | 34篇 |
1990年 | 29篇 |
1989年 | 38篇 |
1988年 | 46篇 |
1987年 | 26篇 |
1986年 | 52篇 |
1985年 | 42篇 |
1984年 | 22篇 |
1983年 | 30篇 |
1982年 | 24篇 |
1981年 | 20篇 |
1980年 | 15篇 |
1979年 | 14篇 |
1978年 | 17篇 |
1977年 | 11篇 |
1976年 | 19篇 |
1975年 | 7篇 |
1968年 | 3篇 |
排序方式: 共有1805条查询结果,搜索用时 15 毫秒
1.
2.
3.
Intracranial circulation: pulse-sequence considerations in three- dimensional (volume) MR angiography 总被引:2,自引:0,他引:2
The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study. 相似文献
4.
Vasileios Mourmouras Gabriele Cevenini Elena Cosci Maria C. Epistolato Maurizio Biagioli Letizia Barbagli Pietro Luzi Susanna Mannucci and Clelia Miracco 《Journal of cutaneous pathology》2009,36(6):637-646
Background: Nucleolin is a major nucleolar argyrophilic protein involved in carcinogenesis. There are only few studies on its tissue expression in human cancer and none in melanoma. We aimed at exploring this protein and its prognostic impact in cutaneous melanocytic lesions.
Methods: We studied 193 cases including benign, dysplastic and malignant melanocytic lesions. Nuclear positivity was evaluated by immunohistochemistry and quantified by automated image analysis.
Results: Most dysplastic and malignant lesions showed high percentages of cells with abnormal patterns of nuclear positivity (Abn+N) consisting in multiple, irregular, positive dots (ID+) and a coarse, irregularly positive nucleoplasm (CNpl+) or both (ID+CNpl+). The patterns CNpl+ and/or ID+CNpl+ were never observed in benign lesions, in which ID+ were also virtually absent. Abn+N% was significantly lower in dysplastic nevi than in primary melanomas and metastases and in primary melanomas than in metastases (p < 0.05). Furthermore, Abn+N was the second powerful prognostic discriminator, after melanoma thickness, and a significantly lower survival was observed in vertical growth phase melanoma patients showing Abn+N in more than 50% of melanoma cells.
Conclusion: An altered nuclear nucleolin expression seems to accompany melanoma progression. Further investigation on nucleolin functionality and subcellular trafficking could add information on its altered role in melanoma. 相似文献
Methods: We studied 193 cases including benign, dysplastic and malignant melanocytic lesions. Nuclear positivity was evaluated by immunohistochemistry and quantified by automated image analysis.
Results: Most dysplastic and malignant lesions showed high percentages of cells with abnormal patterns of nuclear positivity (Abn+N) consisting in multiple, irregular, positive dots (ID+) and a coarse, irregularly positive nucleoplasm (CNpl+) or both (ID+CNpl+). The patterns CNpl+ and/or ID+CNpl+ were never observed in benign lesions, in which ID+ were also virtually absent. Abn+N% was significantly lower in dysplastic nevi than in primary melanomas and metastases and in primary melanomas than in metastases (p < 0.05). Furthermore, Abn+N was the second powerful prognostic discriminator, after melanoma thickness, and a significantly lower survival was observed in vertical growth phase melanoma patients showing Abn+N in more than 50% of melanoma cells.
Conclusion: An altered nuclear nucleolin expression seems to accompany melanoma progression. Further investigation on nucleolin functionality and subcellular trafficking could add information on its altered role in melanoma. 相似文献
5.
Thiazolidinediones (TZDs), agonists of the nuclear receptor peroxisome proliferator-activated receptor-γ, induce the expression
of many genes, including several enzymes and transporters involved in glucose and lipid metabolism. Although the efficacy
of TZDs on blood glucose control in type 2 diabetes is not questionable, their cardiovascular effects have been debated, with
beneficial or harmful actions suggested by different authors. This article reviews the available clinical evidence on the
cardiovascular effects of TZDs, discussing possible mechanisms underlying the observed effects and suggesting some directions
for future research. 相似文献
6.
C.K. Kasper J.B. Graham P.B.A. Kernoff M.J. Larrieu K.A. Rickard and Prof. P.M. Mannucci 《Vox sanguinis》1989,56(3):141-144
Since 1982, when the World Federation of Hemophilia first published a document on the state of the art of hemophilia diagnosis and care, there have been lights and shadows in this field. Although the widespread infection of hemophiliacs with the human immunodeficiency virus (HIV) contaminating clotting factor concentrates is still a threatening and formidable shadow, the gloomy picture brought about by the AIDS epidemic is partially lightened by spectacular improvements in therapy and diagnosis. Carrier detection and first-trimester prenatal diagnosis can now be performed accurately in most kindreds by analysis of DNA of the factor VIII or IX genes. An important step forward towards the elimination of the risk of blood-borne infections transmitted by plasma products was recently made through the application of virucidal methods to clotting factor concentrates. Since HIV appears more vulnerable to such methods than the hepatitis viruses, currently available concentrates can be considered substantially free from the risk of transmitting HIV infection. Even though transmission of hepatitis is much reduced but not totally abolished, virucidal methods are continuously being improved, so that it can be foreseen that concentrates will become safer and safer. Finally, factor VIII produced by recombinant DNA technology is undergoing the first clinical trials in hemophiliacs. Hopefully, it will free from the risk of transmitting infections and will be available in sufficiently large amounts to meet the need of hemophiliacs worldwide. In 1982, the World Federation of Hemophilia published a message on the status of diagnosis and treatment of hemophilia. Since then, hemophilia care has been complicated by widespread infection of hemophiliacs with human immunodeficiency virus (HIV).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
7.
8.
9.
Ralls PW; Johnson MB; Kanel G; Dobalian DM; Colletti PM; Boswell WD Jr; Radin DR; Halls JM 《Radiology》1986,161(2):451-454
FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease. 相似文献
10.