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   719篇
  免费   39篇
  国内免费   5篇
耳鼻咽喉   7篇
儿科学   34篇
妇产科学   19篇
基础医学   94篇
口腔科学   4篇
临床医学   61篇
内科学   152篇
皮肤病学   5篇
神经病学   150篇
特种医学   8篇
外科学   54篇
综合类   7篇
预防医学   86篇
眼科学   27篇
药学   20篇
中国医学   1篇
肿瘤学   34篇
  2024年   2篇
  2023年   3篇
  2022年   9篇
  2021年   18篇
  2020年   14篇
  2019年   19篇
  2018年   22篇
  2017年   12篇
  2016年   12篇
  2015年   17篇
  2014年   28篇
  2013年   38篇
  2012年   52篇
  2011年   48篇
  2010年   24篇
  2009年   34篇
  2008年   44篇
  2007年   50篇
  2006年   54篇
  2005年   35篇
  2004年   28篇
  2003年   30篇
  2002年   27篇
  2001年   19篇
  2000年   14篇
  1999年   17篇
  1998年   9篇
  1997年   3篇
  1996年   6篇
  1994年   4篇
  1993年   2篇
  1992年   3篇
  1991年   6篇
  1990年   14篇
  1989年   3篇
  1988年   9篇
  1987年   4篇
  1986年   5篇
  1985年   4篇
  1983年   6篇
  1982年   1篇
  1981年   2篇
  1980年   2篇
  1979年   1篇
  1978年   1篇
  1976年   2篇
  1974年   1篇
  1970年   1篇
  1965年   1篇
  1964年   1篇
排序方式: 共有763条查询结果,搜索用时 15 毫秒
61.
Objectives  To examine the association between dietary factors to daily activity energy expenditure (DAEE) and mortality among older adults. Design and setting  A sub-study of Health, Aging, and Body Composition study. Participants  298 older participants (aged 70–82 years) in the Health, Aging, and Body Composition Energy Expenditure sub-study. Measurements  Dietary factors, DAEE, and all-cause mortality were measured in 298 older participants. Dietary factors include dietary intake assessed by the Block Food Frequency Questionnaire (FFQ), Healthy Eating Index (HEI), and self-reported appetite and enjoyment of eating. DAEE was assessed using doubly labeled water. All-cause mortality was evaluated over a 9 year period. Results  Participants in the highest tertile of DAEE were more likely to be men and to report having a ‘good’ appetite; BMI among men, proportion married, IL-6 and CRP levels and energy intake were also higher. Fewer black participants were in the ‘good’ HEI category. Participants in the ‘good’ HEI category had higher cognitive scores and a higher education level. Participants who reported improvement in their appetite as well as participants who reported a ‘good’ appetite were at lower risk for mortality (HR (95% CI): 0.42 (0.24–0.74) and 0.50 (0.26–0.88), respectively) even after adjusting for DAEE, demographic, nutritional and health indices. Conclusions  We showed an association between DAEE and appetite and mortality among well-functioning, community-dwelling older adults. These findings may have some practical use for the health providers. Inclusion of a question regarding appetite of an elderly patient may provide important information regarding risk for health deterioration and mortality.  相似文献   
62.
We investigated both the structural and functional consequences of modifying the hydrophobic, lipopeptide-mimetic oligo-acyl-lysine (OAK) N(alpha)-hexadecanoyl-l-lysyl-l-lysyl-aminododecanoyl-l-lysyl-amide (c(16)KKc(12)K) to its unsaturated analog hexadecenoyl-KKc(12)K [c(16(omega7))KKc(12)K]. Despite similar tendencies for self-assembly in solution (critical aggregation concentrations, approximately 10 muM), the analogous OAKs displayed dissimilar antibacterial properties (e.g., bactericidal kinetics taking minutes versus hours). Diverse experimental evidence provided insight into these discrepancies: whereas c(16(omega7))KKc(12)K created wiry interconnected nanofiber networks, c(16)KKc(12)K formed both wider and stiffer fibers which displayed distinct binding properties to phospholipid membranes. Unsaturation also shifted their gel-to-liquid transition temperatures and altered their light-scattering properties, suggesting the disassembly of c(16(omega7))KKc(12)K in the presence of bacteria. Collectively, the data indicated that the higher efficiency in interfering with bacterial viability emanated from a wobbly packing imposed by a single double bond. This suggests that similar strategies might improve hydrophobic OAKs and related lipopeptide antibiotics.  相似文献   
63.
64.
Gelastic seizures comprise a very rare form of epilepsy. They present with recurrent bursts of laughter voices without mirth and are most commonly associated with the evolution of a hypothalamic hamartoma. The purpose of this article is to describe the second reported ictal fluorodeoxyglucose-positron emission tomography study in a unique case of an infant with intractable gelastic seizures since the neonatal period associated with a hypothalamic hamartoma. The patient presented at 4 months old with recurrent, almost persistent, gelastic seizures consisting of laughter bouts without mirth. The seizures were noticeable at the first week of life and increased in frequency to last up to 12 hours, namely status gelasticus. These gelastic fits were accompanied with focal motor seizures, including unilateral right-eye blinking and mouth twitching. Developmental mile-stones were intact for age. Magnetic resonance imaging of the cortex demonstrated a large hypothalamic hamartoma within the third ventricle, hampering cerebrovascular fluid drainage of the lateral ventricles. An electroencephalography was nondiagnostic. Ictal fluorodeoxyglucose-positron emission tomography demonstrated a large circumscribed hypermetabolic region within the location of the hypothalamic hamartoma, representing localized intense epileptiform activity. The infant became instantly free of all seizure types given minute doses of oral benzodiazepine (clonazepam) and remains completely controlled after 12 months. Her overall development remains intact. This ictal fluorodeoxyglucose-positron emission tomography is the second reported study verifying that the main source of the epileptic activity inducing gelastic seizures originates from the hypothalamic hamartoma itself; therefore, a complementary fluorodeoxyglucose-positron emission tomography study should be considered in any patient presenting with intractable gelastic seizures, especially in those associated with hypothalamic hamartoma, in order to localize the region of epileptiform activity amenable to surgical resection if intensive drug therapy fails.  相似文献   
65.
We describe the cases of three children with encephalitis associated with Coxiella burnetii infection. Neurologic features ranged from status epilepticus and coma to headache and pseudotumor cerebri syndrome. Patients had good response to antibiotic treatment with doxycycline and recovered fully. Q fever should be included in the differential diagnosis of children with encephalitis, and routine serological testing should be considered, especially in endemic areas.  相似文献   
66.
67.
In the present investigation, a series of 5-[(substituted) phenyl]-3-(4-hydroxy-3-methylphenyl)-4,5-dihydro-1H-1-pyrazolyl-2-toluidinomethanethione and 5-[(substituted) phenyl]-3-(4-hydroxy-3-methylphenyl)-4,5-dihydro-1H-1-pyrazolyl-2-methoxyanilinomethanethione were synthesized and were tested for their antimycobacterial activity in vitro against isoniazid (INH) resistant Mycobacteium tuberculosis (INHR-MTB). Compound 6i was found to be the most potent derivative of the series with an MIC value of 0.90 mg/mL. When compared to INH, compound 6i was ca. 2-fold more active against INH resistant Mycobacterium tuberculosis (INHR-MTB).  相似文献   
68.
The role of microenvironment interleukin 1 (IL-1) on 3-methylcholanthrene (3-MCA)-induced carcinogenesis was assessed in IL-1-deficient mice, i.e., IL-1beta(-/-), IL-1alpha(-/-), IL-1alpha/beta(-/-) (double knockout), and mice deficient in the naturally occurring inhibitor of IL-1, the IL-1 receptor antagonist (IL-1Ra). Tumors developed in all wild-type (WT) mice, whereas in IL-1beta-deficient mice, tumors developed slower and only in some of the mice. In IL-1Ra-deficient mice, tumor development was the most rapid. Tumor incidence was similar in WT and IL-1alpha-deficient mice. Histologic analyses revealed fibrotic structures forming a capsule surrounding droplets of the carcinogen in olive oil, resembling foreign body-like granulomas, which appeared 10 days after injection of 3-MCA and persisted until the development of local tumors. A sparse leukocyte infiltrate was found at the site of carcinogen injection in IL-1beta-deficient mice, whereas in IL-1Ra-deficient mice, a dense neutrophilic infiltrate was observed. Treatment of IL-1Ra-deficient mice with recombinant IL-1Ra but not with an inhibitor of tumor necrosis factor abrogated the early leukocytic infiltrate. The late leukocyte infiltrate (day 70), which was dominated by macrophages, was also apparent in WT and IL-1alpha-deficient mice, but was nearly absent in IL-1beta-deficient mice. Fibrosarcoma cell lines, established from 3-MCA-induced tumors from IL-1Ra-deficient mice, were more aggressive and metastatic than lines from WT mice; cell lines from IL-1-deficient mice were the least invasive. These observations show the crucial role of microenvironment-derived IL-1beta, rather than IL-1alpha, in chemical carcinogenesis and in determining the invasive potential of malignant cells.  相似文献   
69.
70.
Rationale, aims and objectives  Despite advances in our understanding of cognitive biases in clinical practice, little is known about correction or prevention of diagnostic errors. The presence of a single misleading detail may lead clinicians down a cognitive and actual path toward an incorrect diagnosis.
Methods  In a large teaching hospital, we surveyed 51 attending doctors in internal medicine, presenting each with 10 clinical vignettes and soliciting their diagnosis of the condition leading to the presentation. Each of the 10 clinical cases included a single misleading detail.
Results  This survey elicited a wrong diagnosis in 90% of cases, which was reduced to 30% when omitting the misleading detail from the vignette. Diagnostic accuracy did not improve by warning doctors about potentially misleading information. Asking doctors to identify a leading diagnostic detail and then to formulate an alternative diagnosis after omission of the detail, significantly reduced diagnostic error rate by nearly 50%.
Conclusion  Systematic re-examination of leading diagnostic clues may help to reduce errors in diagnosis.  相似文献   
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