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   6316篇
  免费   397篇
  国内免费   66篇
耳鼻咽喉   50篇
儿科学   167篇
妇产科学   104篇
基础医学   909篇
口腔科学   506篇
临床医学   495篇
内科学   1415篇
皮肤病学   149篇
神经病学   494篇
特种医学   226篇
外科学   586篇
综合类   47篇
一般理论   1篇
预防医学   544篇
眼科学   143篇
药学   636篇
中国医学   57篇
肿瘤学   250篇
  2023年   55篇
  2022年   124篇
  2021年   205篇
  2020年   126篇
  2019年   168篇
  2018年   223篇
  2017年   143篇
  2016年   144篇
  2015年   166篇
  2014年   262篇
  2013年   307篇
  2012年   460篇
  2011年   491篇
  2010年   298篇
  2009年   229篇
  2008年   363篇
  2007年   396篇
  2006年   288篇
  2005年   283篇
  2004年   259篇
  2003年   201篇
  2002年   166篇
  2001年   125篇
  2000年   128篇
  1999年   111篇
  1998年   73篇
  1997年   60篇
  1996年   59篇
  1995年   45篇
  1994年   32篇
  1993年   31篇
  1992年   64篇
  1991年   50篇
  1990年   56篇
  1989年   71篇
  1988年   60篇
  1987年   42篇
  1986年   43篇
  1985年   42篇
  1984年   19篇
  1983年   24篇
  1979年   19篇
  1978年   21篇
  1977年   22篇
  1974年   17篇
  1973年   22篇
  1970年   14篇
  1969年   16篇
  1967年   15篇
  1922年   13篇
排序方式: 共有6779条查询结果,搜索用时 15 毫秒
91.
The application of assisted reproductive technologies (ART) has revolutionised the treatment of human infertility, giving hope to the patients previously considered incapable of establishing pregnancy. While semen analysis is performed to access whether a sample has an adequate number of viable, motile and morphologically normal sperm cells able to achieve fertilisation, sperm selection techniques for ART aim to isolate the most competent spermatozoon which is characterised by the highest fertilising potential. Based on the semen analysis results, the correct sperm selection technique must be chosen and applied. In this review, different sperm selection strategies for retrieving spermatozoa with the highest fertilising potential and their impact on ART outcomes are discussed. In addition, advantages and disadvantages of each method and the best suited techniques for each clinical scenario are described.  相似文献   
92.
A small scale documentation analysis was conducted to explore the medical and surgical nursing content of the patient record at a large teaching hospital affiliated with Partners Healthcare System (PHS), in preparation for a computerized documentation system. Through this study, we identified a number of problems associated with the paper record that require resolution in the new computerized system, including elimination of documentation redundancy, areas where more structure is needed to properly capture data on nursing practice, and various design considerations to support a more complete and accurate documentation of nursing care.  相似文献   
93.
In this questionnaire study, the authors compared the prevalence of certain symptoms and signs associated with Sick Building Syndrome and perceptions relative to environmental discomfort of employees in a central-air-conditioned shopping center and in natural-ventilation commercial shops located on the streets of Niteröi, Rio de Janeiro, Brazil. There was a statistically significant higher prevalence of symptoms (e.g., water and itching of eyes, sore throat, nose irritation, difficulty breathing, skin irritation, sneezing) that were characteristic of Sick Building Syndrome in the air-conditioned building than in the naturally ventilated stores. The results indicated that there exists a continuing need for further research in Brazilian work environments.  相似文献   
94.
Objectives To estimate, by neonatal screening, the birth prevalence of congenital toxoplasmosis among live‐born infants in Sergipe state, Brazil, and to investigate the clinical features of affected infants. Methods Dried blood spot specimens obtained from 15 204 neonates were assayed for the presence of anti‐T. gondii IgM antibodies. Duplicate retesting was done in infants with positive and borderline results. Confirmatory testing in peripheral blood samples consisted of testing for anti‐T. gondii IgG and IgM in infants and mothers. Those with possible congenital toxoplasmosis were evaluated and followed up to a median age of 20 months. Congenital infection was confirmed in the presence of persisting anti‐T. gondii IgG antibodies beyond 12 months of age. All infants with confirmed infection were treated with pyrimethamine, sulfadiazine and folinic acid for 1 year. Results Fifty‐three infants had detectable IgM in dried blood spot specimens. Confirmatory testing was reactive in 39/50, of which, 38 completed follow‐up. Six of 15 204 newborns were diagnosed with congenital toxoplasmosis, resulting in an estimated birth prevalence of four per 10 000 [CI 95% 1.4–8.0]. Four infants (67%) showed signs of congenital toxoplasmosis in their first year of life; three (75%) had retinochoroidal scars, and one had cerebral calcifications. Two infants remained asymptomatic until 20 months of age. Conclusions The birth prevalence of congenital toxoplasmosis is high in the Brazilian state of Sergipe, with most of the infants showing ocular lesions. Preventive measures are strongly warranted.  相似文献   
95.
96.
Radiotherapy (RDT) is commonly used for cancer treatment, but high doses of ionizing radiation can directly affect healthy tissues. Positive biological effects of low-level laser therapy (LLLT) on bone repair have been demonstrated; however, this effect on surgical defects of bone previously compromised by radiotherapy has not been evaluated. The aim of this study was to investigate the influence of LLLT (λ?=?830 nm) in femur repair after ionizing radiation. Twenty Wistar rats were divided into four groups: control group (GC, n?=?5) creation of bone defects (BDs) only; laser group (GL), with BD and LLLT (n?=?5); radiotherapy group (GR), submitted to RDT and BD (n?=?5); and radiotherapy and laser group (GRL), submitted to RDT, BD, and LLLT (n?=?5). GL and GRL received punctual laser application (DE?=?210 J/cm2, P?=?50 mW, t?=?120 s, and beam diameter of 0.04 cm2) immediately after surgery, with 48-h interval during 7 days. Animals were euthanized at 7 days after surgery, and bone sections were evaluated morphometrically with conventional microscopy. Bone repair was only observed in nonirradiated bone, with significant improvement in GL in comparison to GC. GR and GRL did not present any bone neoformation. The result demonstrated a positive local biostimulative effect of LLLT in normal bone. However, LLLT was not able to revert the bone metabolic damage due to ionizing radiation.  相似文献   
97.
Enterococci are increasingly responsible for nosocomial infections worldwide. This study was undertaken to compare the identification and susceptibility profile using an automated MicrosScan system, PCR-based assay and disk diffusion assay of Enterococcus spp. We evaluated 30 clinical isolates of Enterococcus spp. Isolates were identified by MicrosScan system and PCR-based assay. The detection of antibiotic resistance genes (vancomycin, gentamicin, tetracycline and erythromycin) was also determined by PCR. Antimicrobial susceptibilities to vancomycin (30 µg), gentamicin (120 µg), tetracycline (30 µg) and erythromycin (15 µg) were tested by the automated system and disk diffusion method, and were interpreted according to the criteria recommended in CLSI guidelines. Concerning Enterococcus identification the general agreement between data obtained by the PCR method and by the automatic system was 90.0% (27/30). For all isolates of E. faecium and E. faecalis we observed 100% agreement. Resistance frequencies were higher in E. faecium than E. faecalis. The resistance rates obtained were higher for erythromycin (86.7%), vancomycin (80.0%), tetracycline (43.35) and gentamicin (33.3%). The correlation between disk diffusion and automation revealed an agreement for the majority of the antibiotics with category agreement rates of > 80%. The PCR-based assay, the van(A) gene was detected in 100% of vancomycin resistant enterococci. This assay is simple to conduct and reliable in the identification of clinically relevant enterococci. The data obtained reinforced the need for an improvement of the automated system to identify some enterococci.  相似文献   
98.
99.
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