首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   7121篇
  免费   372篇
  国内免费   76篇
耳鼻咽喉   28篇
儿科学   142篇
妇产科学   133篇
基础医学   1073篇
口腔科学   148篇
临床医学   426篇
内科学   1748篇
皮肤病学   252篇
神经病学   601篇
特种医学   250篇
外科学   1105篇
综合类   23篇
预防医学   178篇
眼科学   73篇
药学   516篇
中国医学   18篇
肿瘤学   855篇
  2023年   29篇
  2022年   94篇
  2021年   148篇
  2020年   76篇
  2019年   102篇
  2018年   149篇
  2017年   158篇
  2016年   169篇
  2015年   170篇
  2014年   244篇
  2013年   280篇
  2012年   468篇
  2011年   518篇
  2010年   305篇
  2009年   243篇
  2008年   427篇
  2007年   502篇
  2006年   490篇
  2005年   489篇
  2004年   479篇
  2003年   502篇
  2002年   474篇
  2001年   74篇
  2000年   64篇
  1999年   91篇
  1998年   125篇
  1997年   81篇
  1996年   69篇
  1995年   73篇
  1994年   65篇
  1993年   53篇
  1992年   44篇
  1991年   39篇
  1990年   36篇
  1989年   41篇
  1988年   19篇
  1987年   23篇
  1986年   11篇
  1985年   16篇
  1984年   13篇
  1983年   10篇
  1982年   18篇
  1981年   9篇
  1980年   12篇
  1979年   14篇
  1978年   8篇
  1977年   7篇
  1976年   6篇
  1973年   7篇
  1969年   5篇
排序方式: 共有7569条查询结果,搜索用时 15 毫秒
91.

Background  

Neuromyelitis optica (NMO) is a recurring inflammatory neurological disease characterized by severe optic neuritis and myelitis. The purpose of this study was to determine whether the retinal nerve fiber layer thickness (RNFLT) is correlated with the clinical presentations in patients with NMO and to determine the clinical factors that lead to poor visual outcomes.  相似文献   
92.
Fabry disease is a rare X-linked lysosomal storage disorder caused by mutations in the alpha-galactosidase A (GLA) gene that results in deficiency of the enzyme GLA and leads to the accumulation of globotriaosylceramide (GL-3) in cells. The accumulation of GL-3 may lead to life-threatening complications. Significant advances in genetic sequencing technology have led to a better understanding of genotype-phenotype interactions in Fabry disease. Fabry disease with an R112H mutation is known as the non-classic type. However, the long-term clinical course of the disease remains unknown. We herein report a patient with a 30-year natural history of non-classic Fabry disease with an R112H mutation.  相似文献   
93.
94.
PURPOSE: To investigate the association of magnetic resonance imaging (MRI) of anterior optic pathway with glaucomatous visual field damage and optic disc cupping. SUBJECTS AND METHODS: Twenty-three healthy volunteers (controls) and 31 glaucoma patients (14 with primary open angle glaucoma and 17 with normal tension glaucoma) were enrolled. All the participants showed no abnormal signs in their intracranial space and optic tract causing optic nerve atrophy and visual field defect, as confirmed by MRI. Multislice T1-weighted spin-echo imaging was performed in the sagittal plane followed by the coronal plane. MRI enabled the evaluation of the diameter of the optic nerve located in the retro-bulb space and the height of the optic chiasm in an observer-masked fashion. The MRI data were compared with the mean deviation (MD) score of the full threshold static visual field test and the optic cup-disc ratio (C/D ratio). RESULTS: The optic nerve diameter was significantly smaller in glaucoma patients (2.25 +/- 0.33 mm) than in controls (2.47 +/- 0.24 mm) and the height of the optic chiasm was significantly shorter in glaucoma patients (2.12 +/- 0.37 mm) than in controls (2.77 +/- 0.36 mm). The optic nerve diameter showed significant correlation with MD score (r = 0.547, P = 0.001) and C/D ratio (r = 0.407, P = 0.009). These correlations are similar to that between MD score and C/D ratio (r = 0.490, P = 0.001). The height of the optic chiasm showed significant correlation with MD score (r = 0.503, P = 0.01) and low correlation with C/D ratio (r = 0.339, P = 0.113). CONCLUSION: Glaucoma affects the anterior visual pathway anterogradely at least up to the optic chiasm, and these morphologic changes in the anterior visual pathway are correlated with glaucomatous optic nerve damage. MRI of the anterior visual pathway may be a good tool for evaluating glaucomatous damage objectively.  相似文献   
95.
96.
97.
OBJECTIVE: To examine the obstetrical risk factors for death and brain injury among extremely-low-birth-weight (ELBW) infants (birth weight <1000 g). STUDY DESIGN: Study subjects were 121 ELBW infants born at a single tertiary perinatal center. Death among ELBW infants was considered to have occurred when subjects died within their corrected age of 40 weeks. In the sub-analysis of the 91 ELBW infants who survived their corrected age of 40 weeks, brain injury was defined as present when criteria based on ultrasound and/or MRI were substantiated. RESULTS: A birth weight of <800 g [adjusted odds ratio (OR), 14.57; 95% confidence interval (CI), 4.72-56.98], a younger gestational age of <26 weeks (adjusted OR, 4.64; 95% CI, 1.60-14.90), and a low Apgar score of <5 (adjusted OR, 3.88; 95% CI, 1.32-12.45) were significantly associated with death among ELBW infants. A maternal age of 30 years or older (adjusted OR, 3.71; 95% CI, 1.19-13.35) was only associated with brain injury among surviving ELBW infants. CONCLUSION: Obstetrical care should be aimed at preventing or predicting premature delivery especially at <26 weeks of gestation.  相似文献   
98.
OBJECTIVE: The purpose of the present study was to clarify the association of serum cytokine concentrations, determined using a multiplexed cytokine assay, with psychological symptoms in midlife women. METHODS: Fifty-three peri- and post-menopausal women with and without psychological symptoms in Greene's climacteric scale were enrolled in this study. Levels of 17 cytokines in serum samples were measured simultaneously using a multiplexed human cytokine assay. RESULTS: Serum interleukin (IL)-6 concentration in women with psychological symptoms (2.71+/-047 pg/ml) was significantly (p=0.009) higher than that in women without psychological symptoms (0.98+/-0.18 pg/ml). Serum IL-8 concentration in women with psychological symptoms (33.4+/-8.17 pg/ml) was also significantly (p=0.022) higher than that in women without psychological symptoms (7.87+/-1.64 pg/ml). In addition, serum IL-10 concentration in women with psychological symptoms (0.74+/-0.26 pg/ml) was significantly (p=0.048) higher than that in women without psychological symptoms (0.07+/-0.04 pg/ml). Tumor necrosis factor (TNF)-alpha in serum was detected only in women with psychological symptoms. Serum IL-2 concentration in women with psychological symptoms tended (p=0.066) to be higher than that in women without psychological symptoms. No significant differences were found between levels of other cytokines in women with and without psychological symptoms. CONCLUSION: Psychological stress manifested as climacteric symptoms in midlife women may be associated with increases in serum concentrations of IL-6, IL-8, IL-10, and TNF-alpha.  相似文献   
99.
We developed a series of blue-emitting 1,8-naphthalimide dyes covalently attached to 2-(2-hydroxyphenyl)-2H-benzotriazoles that retard photodegradation of the fluorophore. The dyes displayed weaker fluorescence emissions than the parent 1.8-naphthalimide. Quantum chemical calculations suggested that the decreased fluorescence was caused by the nonradiative deactivation promoted through the excited state intramolecular proton transfer (ESIPT) in benzotriazole components. The dyes'' phosphorescences in a degassed solution at 77 K were more efficient than that of the parent 1.8-naphthalimide, indicating a possible deactivation pathway through intersystem crossing. PMMA films doped with these dyes showed higher resistance against photoaging than the film doped with an equimolar mixture of constituent 1.8-naphthalimide and the benzotriazole derivatives. Thus, the covalently linked benzotriazole units slow fluorophore degradation not only by preferential absorption of harmful UV light, which is found in the film with a simple mixture of two components, but also by the nonradiative deactivation involved in benzotriazole units.

Highly photostable blue fluorescence dyes were developed by hybridization of 1,8-naphthalimides with benzotriazole-based UV absorbers enabling a non-radiative energy dissipation process of excited-state intramolecular proton transfer (ESIPT).  相似文献   
100.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号