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   5341篇
  免费   310篇
  国内免费   38篇
耳鼻咽喉   108篇
儿科学   172篇
妇产科学   116篇
基础医学   864篇
口腔科学   552篇
临床医学   374篇
内科学   1059篇
皮肤病学   138篇
神经病学   440篇
特种医学   98篇
外科学   430篇
综合类   25篇
一般理论   3篇
预防医学   507篇
眼科学   70篇
药学   401篇
中国医学   25篇
肿瘤学   307篇
  2024年   4篇
  2023年   42篇
  2022年   47篇
  2021年   228篇
  2020年   163篇
  2019年   189篇
  2018年   205篇
  2017年   129篇
  2016年   184篇
  2015年   226篇
  2014年   261篇
  2013年   333篇
  2012年   448篇
  2011年   526篇
  2010年   288篇
  2009年   244篇
  2008年   336篇
  2007年   361篇
  2006年   335篇
  2005年   300篇
  2004年   260篇
  2003年   192篇
  2002年   165篇
  2001年   22篇
  2000年   13篇
  1999年   19篇
  1998年   17篇
  1997年   22篇
  1996年   17篇
  1995年   13篇
  1994年   5篇
  1993年   13篇
  1992年   7篇
  1991年   5篇
  1988年   9篇
  1987年   3篇
  1986年   4篇
  1985年   6篇
  1983年   9篇
  1982年   2篇
  1981年   3篇
  1980年   2篇
  1979年   2篇
  1977年   4篇
  1975年   4篇
  1974年   2篇
  1973年   2篇
  1972年   3篇
  1971年   2篇
  1955年   2篇
排序方式: 共有5689条查询结果,搜索用时 109 毫秒
41.
42.
Lasers in Medical Science - This study compared the effects of LED therapy associated with occlusal splint (OS) on the signs and symptoms of temporomandibular disorder (TMD). In this randomized,...  相似文献   
43.
Infertility is a major health issue affecting over 48.5 million couples around the world, with the male factor accounting for about 50% of the cases. The conventional semen analysis recommended by the World Health Organization (WHO) is the cornerstone in the evaluation of male fertility status. It includes macroscopic and microscopic evaluation of the ejaculate, which reflects the production of spermatozoa in the testes, the patency of the duct system and the glandular secretory activity. Evaluation of seminal fructose, sperm vitality and leucocytes (Endtz test) are useful adjuncts to semen analysis that provide information on specific clinical conditions. Though several computer-assisted sperm analysis (CASA) systems have been developed, conventional methods for semen analysis are still widely accepted in clinical practice. This review summarises the conventional techniques used in routine semen analysis and their diagnostic value in clinical andrology.  相似文献   
44.
BackgroundAccurate resuscitation of pediatric patients with large thermal injury is critical to achieving optimal outcomes. The goal of this project was to describe the degree of variability in resuscitation guidelines among pediatric burn centers and the impact on fluid estimates.MethodsFive pediatric burn centers in the Pediatric Injury Quality Improvement Collaborative (PIQIC) contributed data from patients with ≥15% total body surface area (TBSA) burns treated from 2014 to 2018. Each center's resuscitation guidelines and guidelines from the American Burn Association were used to calculate estimated 24-h fluid requirements and compare these values to the actual fluid received.ResultsDifferences in the TBSA burn at which fluid resuscitation was initiated, coefficients related to the Parkland formula, criteria to initiate dextrose containing fluids, and urine output goals were observed. Three of the five centers’ resuscitation guidelines produced statistically significant lower mean fluid estimates when compared with the actual mean fluid received for all patients across centers (4.53 versus 6.35 ml/kg/% TBSA, p < 0.001), (4.90 versus 6.35 ml/kg/TBSA, p = 0.002) and (3.38 versus 6.35 ml/kg/TBSA, p < 0.0001).ConclusionsThis variation in practice patterns led to statistically significant differences in fluid estimates. One center chose to modify its resuscitation guidelines at the conclusion of this study.  相似文献   
45.
BackgroundDespite the vast literature studying the opioid crisis, sparse data describe this in the pediatric burn population. This study sought to assess patient-level characteristics and their potential effects on opioid administration in nonsurgical pediatric burn inpatients.MethodsAdmitted burn patients from 2013 to 2018 with nonsurgical management at an American Burn Association (ABA) verified pediatric burn center were retrospectively identified. Morphine milligram equivalents by weight (MME/kg) per admission were evaluated through a multiple loglinear regression with race, sex, age, total body surface area burned (TBSA), and burn depth as predictors. Simple linear regression was used to evaluate the temporal trend of median opioid utilization.ResultsA total of 806 patients (55% White, 35% Black, 5% Hispanic, 5% Other) were included. In an adjusted analysis, no differences in opioid administration were seen by sex, burn degree, or for Blacks and Hispanics when compared with Whites. Increased MME/kg was associated with older age (10–18 years; p < 0.0001) and larger burns (>5% TBSA burned; p < 0.0001). From 2013 to 2018, median MME/kg per admission declined significantly (2013:0.21, 2018:0.09; p = 0.0103).ConclusionsNonsurgical burn patients who were older and presented with larger TBSA experienced marked increases in opioid utilization. Overall, opioid administration decreased over time.  相似文献   
46.
47.
BACKGROUND: Androgenetic alopecia (AGA) is a common, genetically predisposed condition that begins after puberty and whose frequency increases with age; although biologically benign, AGA can impact patients both psychologically and socially, contributing to an impairment on their quality of life. OBJECTIVE: We sought to evaluate the psychological, social, and quality of life impairments inherent in women with AGA using 5% minoxidil daily for at least six months. DESIGN: Thirty-one women with diffuse central hair thinning and shaft miniaturization who were using 5% minoxidil daily for at least six months responded to a clinical questionnaire and underwent trichoscopy. RESULTS: 83.9 percent (n=26) of the participants reported they were satisfied with the 5% minoxidil treatment and its convenience. Hair loss influenced social life in 54.8 percent (n=17) of the respondents and choice of hair cut/hairstyle in 87.1 percent (n=27) of respondents. For 51.6 percent (n=16) hair loss was slightly increased, although it did not increase after beginning treatment. A frontoparietal pattern (74.2%, n=23), very low capillary density (61.3%, n=19), trichodynia (32.3%, n=10), and negative traction test (100%, n=31) were also observed. Miniaturization occurred in 100 percent (n=31) of patients, frontal/occipital hair thickness was reduced in 83.9 percent (n=26), and more than 10 percent of velus hair in the frontal area was observed in 83.9 percent (n=26) of patients. The number of hair shafts per follicular unit was reduced in 67.7 percent (n=21), and a higher frontal to occipital ratio of follicular units with one hair shaft was seen in 74.2 percent (n=23) of patients. Empty follicles, large numbers of peripillar brownish halo, scalp pigmentation, mild Ludwig''s baldness degree, and quality of life scores of 4±3.5 points were observed. CONCLUSION: Our results indicate that patient satisfaction and quality of life of women with AGA on 5% topical minoxidil are high, although hair loss influences daily habits and social life.  相似文献   
48.
Upregulation of the inducible gene products MICA (human) and Rae-1 (mouse) may promote tumor surveillance and autoimmunity by engaging the activating receptor NKG2D on natural killer (NK) cells and T cells. Nevertheless, sustained expression of MICA by tumors can also elicit NKG2D downregulation, perhaps indicating 'immunoevasion'. Investigating this paradox, we report here that constitutive Rae-1epsilon transgene expression in normal epithelium elicited local and systemic NKG2D downregulation, generalized but reversible defects in NK cell-mediated cytotoxicity and mild CD8(+) T cell defects. The extent of NKG2D downregulation correlated well with the incidence and progression of cutaneous carcinogenesis, emphasizing the utility of NKG2D as a marker of tumor resistance. Thus, NKG2D engagement is a natural mediator of immunosurveillance, which can be compromised by locally sustained ligand expression but potentially restored by innate immune activation.  相似文献   
49.
In the present study the effect of antidepressant drugs on the density of dopamine D2/D3 receptors in the rat forebrain was examined using autoradiography, since this technique provides the appropriate anatomical resolution. Male Wistar rats were treated with three various antidepressant drugs: imipramine, citalopram and mianserin in a dose of 10 mg/kg p.o., acutely (single dose) or repeatedly (twice a day for 14 days). To estimate the distribution of D2/D3 receptors, we chose following radioligands: [3H]raclopride, a non-selective antagonist of D2/D3 receptors, and [3H]quinpirole, a non-selective D2/D3 agonist. When [3H]raclopride was used as a radioligand, no significant differences in the density of D2/D3 receptors were observed after administration of the investigated drugs. However, following repeated administration of imipramine, citalopram and mianserin, a significant increase in the binding of [3H]quinpirole was observed, both in the nucleus caudatus and nucleus accumbens septi. In some cases the increase of [3H]quinpirole binding was also observed after acute treatment with antidepressant drugs. Thus, using an agonist as a radioligand, we were able to see upregulation of dopamine D2/D3 receptors in the rat forebrain following administration of antidepressant drugs, which might be interpreted as the biochemical correlative for the postsynaptic dopamine D2/D3 receptor supersensitivity observed in previous behavioral studies. Received: 13 February 1998 / Accepted: 13 November 1998  相似文献   
50.
Deletion 22q11.2 is a chromosomal abnormality detected in young patients with clinical manifestations of the DiGeorge/velocardiofacial syndrome. Conotruncal heart defects are also associated with del22q11.2. An association of these cardiac malformations with neoplasias has been observed. Our series includes two cases of malignancies, a hepatoblastoma and a renal-cell carcinoma, arising in children with complex cardiac malformations. The aim of the study was to determine if the deletion at 22q11.2 was present and could be responsible for both pathological processes. Del22q11.2 was identified in both cases. Comparative genomic hybridization revealed terminal gains on chromosomes 1q and Xq and terminal loss on 1p in the hepatoblastoma, and gains in 1p, 12q, 16p, 20q, 22q, and whole chromosome 19 and loss of Xq in the renal-cell carcinoma. Our results confirm a common genetic basis for cardiac malformations, and del22q11.2 presents a risk factor for the development of pediatric tumours.  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