全文获取类型
收费全文 | 233612篇 |
免费 | 15819篇 |
国内免费 | 3077篇 |
专业分类
耳鼻咽喉 | 3251篇 |
儿科学 | 4400篇 |
妇产科学 | 6045篇 |
基础医学 | 33080篇 |
口腔科学 | 4617篇 |
临床医学 | 22866篇 |
内科学 | 44661篇 |
皮肤病学 | 5531篇 |
神经病学 | 16695篇 |
特种医学 | 11002篇 |
外国民族医学 | 6篇 |
外科学 | 31523篇 |
综合类 | 6673篇 |
现状与发展 | 12篇 |
一般理论 | 102篇 |
预防医学 | 13813篇 |
眼科学 | 6284篇 |
药学 | 19760篇 |
21篇 | |
中国医学 | 3230篇 |
肿瘤学 | 18936篇 |
出版年
2023年 | 1592篇 |
2022年 | 4175篇 |
2021年 | 7167篇 |
2020年 | 3903篇 |
2019年 | 5376篇 |
2018年 | 6595篇 |
2017年 | 4866篇 |
2016年 | 5820篇 |
2015年 | 8029篇 |
2014年 | 9909篇 |
2013年 | 11945篇 |
2012年 | 17715篇 |
2011年 | 17425篇 |
2010年 | 10399篇 |
2009年 | 8869篇 |
2008年 | 13129篇 |
2007年 | 12983篇 |
2006年 | 12091篇 |
2005年 | 11471篇 |
2004年 | 10263篇 |
2003年 | 9316篇 |
2002年 | 8177篇 |
2001年 | 6614篇 |
2000年 | 5989篇 |
1999年 | 4958篇 |
1998年 | 2008篇 |
1997年 | 1588篇 |
1996年 | 1499篇 |
1995年 | 1349篇 |
1994年 | 1186篇 |
1993年 | 941篇 |
1992年 | 2472篇 |
1991年 | 2293篇 |
1990年 | 2060篇 |
1989年 | 1916篇 |
1988年 | 1770篇 |
1987年 | 1610篇 |
1986年 | 1526篇 |
1985年 | 1311篇 |
1984年 | 1001篇 |
1983年 | 856篇 |
1982年 | 587篇 |
1981年 | 557篇 |
1980年 | 503篇 |
1979年 | 841篇 |
1978年 | 641篇 |
1977年 | 551篇 |
1976年 | 492篇 |
1974年 | 506篇 |
1973年 | 458篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Eun Sang Park Jung Im Na Seon Ok Kim Chang Hun Huh Sang Woong Youn Kyoung Chan Park 《Skin research and technology》2006,12(4):298-302
Background/purpose: Vitiligo and nevus depigmentosus (ND) present similar hypopigmented macules with significantly different prognoses. Although the distinction between the two diseases is important, differential diagnosis relies on medical history and physical examination, which is far from decisive in some cases. The Mexameter® is an objective skin color-measuring device, and has been reported to provide a reproducible and sensitive means of quantifying small skin color differences. In this study, we investigated the usefulness of a Mexameter® for discriminating these diseases.
Methods: A selection of 202 hypopigmented skin lesions (182 from vitiligo and 20 from ND) were the objects of this study. Using a Mexameter, MIs were obtained from lesions and symmetrically located control skin. RMIs, ratios of the MIs of lesional skins to control skins, were calculated.
Results: The mean MIs and RMIs were significantly different for vitiligo and ND. The mean RMI of ND lesions was 74±13, which was significantly higher than that of vitiligo lesions (50±24). No ND lesion had an RMI of <50%.
Conclusion: This study shows that the Mexameter® , an objective pigment-measuring device, can be used to achieve a more accurate diagnosis of hypopigmentary disorders, and that the relative melanin index (RMI), which represents the relative pigment levels, might be a more effective parameter than the melanin index (MI) itself for comparing pigmentation differences. 相似文献
Methods: A selection of 202 hypopigmented skin lesions (182 from vitiligo and 20 from ND) were the objects of this study. Using a Mexameter, MIs were obtained from lesions and symmetrically located control skin. RMIs, ratios of the MIs of lesional skins to control skins, were calculated.
Results: The mean MIs and RMIs were significantly different for vitiligo and ND. The mean RMI of ND lesions was 74±13, which was significantly higher than that of vitiligo lesions (50±24). No ND lesion had an RMI of <50%.
Conclusion: This study shows that the Mexameter
22.
Hirschsprung disease (HSCR) is a congenital disorder characterized by an absence of ganglion cells in the nerve plexuses of the lower digestive tract. Although mutations in eight different genes (EDNRB, EDN3, ECE1, SOX10, RET, GDNF, NTN, SIP1) have been identified in affected individuals, it is now clear that RET and EDNRB are the primary genes implicated in the etiology of HSCR. All eight genes are involved in the early development of the enteric nervous system, and most act through two distinct biochemical pathways mediated by RET and EDNRB. Mutations in RET and EDNRB account for up to 50% and 5% of HSCR cases in the general population, respectively. Interaction between these two signaling pathways could modify RET expression and, therefore, HSCR phenotype. Here, we report the case of a 1-year-old Taiwanese boy who presented with abdominal distension since birth and bilious vomiting after feeding. HSCR (short-segment type) was diagnosed based on X-ray, lower gastrointestinal series and biopsy findings. Mutation analysis revealed a heterozygous T>C missense mutation in exon 1 of the EDNRB gene, that substitutes the highly conserved cysteine-90 residue in the extracellular domain of the G protein-coupled receptor with an arginine residue (C90R). No RET gene mutation was detected in this patient. 相似文献
23.
24.
Mandibular prognathism (MP) or skeletal Class III malocclusion with a prognathic mandible is one of the most severe maxillofacial deformities. Facial growth modification can be an effective method of resolving skeletal Class III jaw discrepancies in growing children with dentofacial orthopedic appliances including the chincup, face mask, maxillary protraction combined with chincup traction and the Fr?nkel functional regulator III appliance. Orthognathic surgery in conjunction with orthodontic treatment is required for the correction of adult MP. The two most commonly applied surgical procedures to correct MP are sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy. Both procedures are suitable for patients in whom a desirable occlusal relationship can be obtained with a setback of the mandible, and each has its own advantages and disadvantages. In bilateral SSRO, the intentional ostectomy of the posterior part of the distal segment can offer long-term positioned stability. This may be attributable to reduction of tension in the pterygomasseteric sling that applies force in the posterior mandible. While various environmental factors have been found to contribute to the development of MP, heredity plays a substantial role. The relative contributions of genetic and environmental components in the etiology of MP are unclear. The recent identification of the genetic susceptibilities to MP constitutes the first step toward understanding the molecular pathogenesis of MP. Further studies in molecular biology are needed to identify the gene-environment interactions associated with the phenotypic diversity of MP and the heterogenic developmental mechanisms thought to be responsible for them. 相似文献
25.
Abstract: Background: Identification of risk drinking in expectant fathers may be helpful as an important part of efforts to minimize maternal alcohol use, and as an opportunity to inform them about a problematic practice during a critical developmental stage for the couple. The purpose of this study was to evaluate the T‐ACE screening questionnaire, which asks about t olerance to alcohol, being a nnoyed by other's comments about drinking, attempts to c ut down, and having a drink first thing in the morning (“ e ye‐opener”), in the male partners of pregnant women who themselves were T‐ACE positive. Methods: Two hundred fifty‐four male partners were asked to complete the T‐ACE embedded in a health survey, the Alcohol Use Disorders Identification Test (AUDIT), and other questions about their alcohol use in the past 30 days when their pregnant partners had a median gestation of 11.5 weeks (T1). After delivery, male partners again completed the T‐ACE and quantity‐frequency questions (T2). The predictive ability of the T‐ACE and AUDIT was compared, using risk drinking (>4 drinks/day or >14 drinks/week) as the criterion standard. Results: A substantial minority of male partners had risk drinking, 31 percent at T1 and 25 percent at T2. Although the AUDIT was better than the T‐ACE as an independent predictor of risk drinking, the latter was most accurate when the tolerance threshold exceeded 2 drinks, the same established for pregnant women. The sensitivity (T1 = 84.6%, T2 = 82.8%) and specificity (T1 = 43.8%, T2 = 51.1%) of the T‐ACE at this threshold compared favorably with those of the AUDIT at the standard cut point of 8. Conclusions: The T‐ACE may be a practical way for clinicians to identify risk drinking in both pregnant women and expectant fathers. (BIRTH 33:2 June 2006) 相似文献
26.
The authors studied the cumulative probability of pregnancy for up to 4 consecutive embryo transfer (ET) cycles with ICSI performed for male factor. Transfers could be either fresh or frozen. The clinical pregnancy rate (PR) for the first 4 cycles were similar [44% (61/366); 31% (44/138); 45% (14/31); 44% (4/9)]. Delivery rates were also similar. There was a lower PR on the second retrieval vs. the first retrieval (47% vs. 29%), but this may be related to most of the second retrievals occurring in the second transfer cycle (67%, 31/55); this may be explained by women who were poor responders and required another retrieval without a frozen ET. The majority of transfers in cycle 1 were fresh, whereas cycles 2-4 used primarily frozen-thawed embryos. These data should be helpful for patients requiring IVF with ICSI in deciding to continue with more IVF cycles or consider other 相似文献
27.
Milton G. Mutchnick MD Horchang H. Lee MD 《Alcoholism, clinical and experimental research》1988,12(1):155-158
Concanavalin A-induced lymphocyte proliferation was studied in 25 patients with alcoholic hepatitis or compensated alcoholic cirrhosis. Nine alcoholics without evidence of liver disease were also evaluated. A nonlinear correlation equation, which was natural logarithmic, was applied to individual dose-response proliferation curves and permitted comparisons between patient groups and controls. The proliferative response in all patient groups was significantly lower when compared to healthy controls and was independent of the presence or absence of liver disease. This suggests that some changes in immune function observed in alcoholics may be linked to the direct effects of alcohol on the immune system rather than to the associated liver disease. 相似文献
28.
29.
A discrete time optimal control for linear time-delay systems is developed to ensure that all closed-loop eigenvalues will lie inside a circular region centred at (β;, 0) with radius α. It is shown that by suitable manipulations the problem can be reduced to a standard discrete time quadratic regulator problem. An illustrative example is included to demonstrate the applicability of the proposed method. 相似文献
30.