全文获取类型
收费全文 | 28869篇 |
免费 | 6836篇 |
国内免费 | 97篇 |
专业分类
耳鼻咽喉 | 456篇 |
儿科学 | 1017篇 |
妇产科学 | 842篇 |
基础医学 | 1977篇 |
口腔科学 | 1602篇 |
临床医学 | 7524篇 |
内科学 | 6314篇 |
皮肤病学 | 785篇 |
神经病学 | 3267篇 |
特种医学 | 689篇 |
外国民族医学 | 1篇 |
外科学 | 3411篇 |
综合类 | 225篇 |
现状与发展 | 2篇 |
一般理论 | 25篇 |
预防医学 | 3878篇 |
眼科学 | 609篇 |
药学 | 898篇 |
中国医学 | 23篇 |
肿瘤学 | 2257篇 |
出版年
2024年 | 228篇 |
2023年 | 1392篇 |
2022年 | 479篇 |
2021年 | 992篇 |
2020年 | 1331篇 |
2019年 | 784篇 |
2018年 | 1797篇 |
2017年 | 1872篇 |
2016年 | 1901篇 |
2015年 | 1937篇 |
2014年 | 2296篇 |
2013年 | 2417篇 |
2012年 | 1509篇 |
2011年 | 1583篇 |
2010年 | 1623篇 |
2009年 | 1954篇 |
2008年 | 1280篇 |
2007年 | 1222篇 |
2006年 | 1176篇 |
2005年 | 961篇 |
2004年 | 892篇 |
2003年 | 819篇 |
2002年 | 714篇 |
2001年 | 372篇 |
2000年 | 232篇 |
1999年 | 341篇 |
1998年 | 375篇 |
1997年 | 377篇 |
1996年 | 360篇 |
1995年 | 329篇 |
1994年 | 215篇 |
1993年 | 201篇 |
1992年 | 183篇 |
1991年 | 160篇 |
1990年 | 141篇 |
1989年 | 146篇 |
1988年 | 128篇 |
1987年 | 104篇 |
1986年 | 91篇 |
1985年 | 110篇 |
1984年 | 79篇 |
1983年 | 59篇 |
1982年 | 59篇 |
1981年 | 48篇 |
1980年 | 42篇 |
1979年 | 50篇 |
1978年 | 56篇 |
1977年 | 43篇 |
1976年 | 42篇 |
1973年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
STUDY OBJECTIVES: It has been suggested that mild hypoxia may not be a potent stimulus for arousal during sleep in infants because infants frequently fail to arouse from quiet sleep (QS). Our aim was to characterize arousal responses of sleeping infants in both active sleep (AS) and QS under normoxic and mildly hypoxic (15% O2) conditions over the first 6 months of life. PARTICIPANTS: Five healthy term and 6 healthy preterm infants were each studied at 2 to 5 weeks, 2 to 3 months, and 5 to 6 months postterm. All infants underwent daytime polysomnography during which nasal airflow was monitored using a purpose-built pneumotachograph. All infants were studied under both normoxic (21% O2) and hypoxic (15% O2, balance N2) conditions (presentation order randomized) in each sleep state at each study age. Tests were terminated at arousal, O2 saturation falling below 85%, or 5 minutes (failure to arouse). MEASUREMENTS: Probability of failure to arouse and mean arousal latency were compared between each experimental condition, with each infant serving as its own control. RESULTS: Infants aroused more frequently under hypoxic conditions than under normoxic conditions. Overall, arousal latencies were shorter during hypoxia compared to normoxia in both sleep states at each age. Arousal latencies were longer in QS compared to AS in both hypoxic and normoxic conditions. CONCLUSION: In sleeping infants, mild hypoxia serves as a stimulus for arousal in both AS and QS. Of particular significance is our finding that arousal from AS is readily elicited by mild hypoxia. 相似文献
102.
Yuzheng Wu MSc Kunio Doi Charles E. Metz Naoki Asada Maryellen L. Giger 《Journal of digital imaging》1993,6(2):117-125
Artificial neural networks are being investigated in the field of medical imaging as a means to facilitate pattern recognition and patient classification. In the work reported here, the effects of internal structure and the nature of input data on the performance of neural networks were investigated systematically using computer-simulated data. Network performance was evaluated quantitatively by means of receiver operating characteristic analysis and compared with the performance of an ideal statistical decision maker. We found that the relatively simple neural networks investigated in this study can perform at the level of an ideal decision maker. These simple networks were also found to learn accurately even when the training data are extremely unbalanced with respect to the prevalence of actually positive cases and to differentiate input data patterns by recognizing their unique characteristics. 相似文献
103.
Hüffmeier U Hausser I Reis A Rauch A 《American journal of medical genetics. Part A》2005,135(2):195-199
We present a family of Iraqui origin with three siblings affected by a novel type of progressive hyperpigmentation syndrome. The generalized initially diffuse, later disseminated hyperpigmentation started in early infancy and increased during childhood. It also affected palms and soles, and the face but spared the cheeks. Additional features were dry, itchy and sunlight sensitive skin, dystrophy of toe nails, hair loss, and myopia, but normal sweat glands. Light and electron microscopy showed signs of pigment incontinence and compound melanosomes as well as fibrillar bodies. The occurrence of this entity in affected siblings from a consanguineous mating suggests autosomal recessive inheritance. Extensive review of the literature showed no previous report with this distinct combination of clinical and microscopic findings. 相似文献
104.
Rauch A Beese M Mayatepek E Dörr HG Wenzel D Reis A Trautmann U 《American journal of medical genetics. Part A》2003,(1):1-8
We observed a novel 3.5 Mb 5q subtelomeric deletion in a 3-year-old girl with developmental delay, hypotonia and multiple minor anomalies. Comparison of her phenotype with the few published patients with terminal 5q35 deletions revealed several overlapping features, but also showed remarkable differences such as shortness of stature versus macrosomia. After the report of 5q35.3 microdeletions in Sotos syndrome we integrated the published BACs into the public draft sequence and exactly mapped the deletion size in our patient by FISH analysis with 15 BAC probes. We demonstrated that the deletion in our patient is immediately adjacent to the reported Sotos syndrome deletion site. Subtracting the symptoms of Sotos syndrome from the published patients with larger 5q35.3 deletions allowed us to delineate a distinct phenotype of prenatal lymphedema with increased nuchal translucency, pronounced muscular hypotonia and delay of reaching motor milestones, but speech development within normal limits, wide fontanels, failure to thrive with postnatal short stature, and multiple minor anomalies such as mildly bell-shaped chest, minor congenital heart disease, and a distinct facial gestalt, associated with the novel 3.5 Mb cryptic deletion. We further showed in our patient that the deletion of the LCT(4) synthase gene results in a reduction of cysteinyl leukotriene synthesis to about 65% compared to normal values. The prenatal nuchal lymphedema associated with this deletion syndrome my be related to the deletion of the FLT4 gene causing autosomal dominant primary lymphedema and contributes to the differential diagnosis of increased fetal nuchal translucency. 相似文献
105.
Werner M Mattis A Aubele M Cummings M Zitzelsberger H Hutzler P Höfler H 《Virchows Archiv : an international journal of pathology》1999,435(5):469-472
The 20q13 region harboring recently described putative oncogenes is frequently amplified in invasive ductal carcinoma (IDC).
The aim of this study was to examine the 20q13 copy number in intraduct hyperplasia (IH), atypical duct hyperplasia (ADH),
and ductal carcinoma in situ (DCIS) adjacent to IDC. In 5 patients, comparative genomic hybridization (CGH) after laser microdissection
revealed 20q13 amplification in four of five cases of IH, in all of three cases of IH with atypia, all five of DCIS, and all
five of IDC. Fluorescence in situ hybridization (FISH) confirmed the amplification at 20q13.2 in IH in the two specimens analyzed.
The amplification rate, however, was higher in DCIS and IDC. In phenotypically normal ductal epithelium normal values were
found for 20q13 copy number by FISH (n=2) and CGH (n=5). Although the number of cases presented here is small, our results suggest that mutations in the 20q13.2 region in IH
may be associated with accelerated proliferation and hyperplasia of the ductal epithelium. Progression to DCIS and ICD is
accompanied by a further increase in the 20q13.2 copy number.
Received: 17 March 1999 / Accepted: 22 June 1999 相似文献
106.
Inactivation of Notch1 impairs VDJbeta rearrangement and allows pre-TCR-independent survival of early alpha beta Lineage Thymocytes 总被引:12,自引:0,他引:12
Notch proteins influence cell fate decisions in many developmental systems. During lymphoid development, Notch1 signaling is essential to direct a bipotent T/B precursor toward the T cell fate, but the role of Notch1 at later stages of T cell development remains controversial. We have recently reported that tissue-specific inactivation of Notch1 in immature (CD44(-) CD25(+)) thymocytes does not affect subsequent T cell development. Here, we demonstrate that loss of Notch1 signaling at an earlier (CD44(+)CD25(+)) developmental stage results in severe perturbation of alpha beta but not gamma delta lineage development. Immature Notch1(-/-) thymocytes show impaired VDJ beta rearrangement and aberrant pre-TCR-independent survival. Collectively, our data demonstrate that Notch1 controls several nonredundant functions necessary for alpha beta lineage development. 相似文献
107.
108.
Anita S. Kulharya Mark Maberry Mary K. Kukolich Donald W. Day Nancy R. Schneider Golder N. Wilson Vijay Tonk 《American journal of medical genetics. Part A》1995,55(2):165-170
We describe clinical and chromosomal findings in two patients with del(4q). Patient 1, with interstitial deletion (4)(q21.1q25), had craniofacial and skeletal anomalies and died at 8 months of hydrocephalus. Patient 2, with interstitial deletion (4)(q25q27), had craniofacial and skeletal anomalies with congenital hypotonia and developmental delay. These patients shared certain manifestations with other del(4q) patients but did not have Rieger anomaly. Clinical variability among patients with interstitial deletions of 4q may be related to variable expression, variable deletion, or imprinting of genes within the 4q region. © 1995 Wiley-Liss, Inc. 相似文献
109.
Inhibition of p38MAP kinase suppresses fibrotic reaction of retinal pigment epithelial cells 总被引:3,自引:0,他引:3
110.