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   3063篇
  免费   136篇
  国内免费   16篇
耳鼻咽喉   59篇
儿科学   128篇
妇产科学   115篇
基础医学   334篇
口腔科学   77篇
临床医学   257篇
内科学   582篇
皮肤病学   89篇
神经病学   197篇
特种医学   72篇
外科学   561篇
综合类   40篇
一般理论   2篇
预防医学   122篇
眼科学   127篇
药学   249篇
中国医学   16篇
肿瘤学   188篇
  2024年   5篇
  2023年   34篇
  2022年   89篇
  2021年   172篇
  2020年   74篇
  2019年   131篇
  2018年   128篇
  2017年   89篇
  2016年   105篇
  2015年   125篇
  2014年   168篇
  2013年   180篇
  2012年   309篇
  2011年   319篇
  2010年   154篇
  2009年   116篇
  2008年   180篇
  2007年   124篇
  2006年   144篇
  2005年   144篇
  2004年   116篇
  2003年   92篇
  2002年   68篇
  2001年   15篇
  2000年   13篇
  1999年   12篇
  1998年   11篇
  1997年   5篇
  1996年   3篇
  1995年   5篇
  1994年   10篇
  1992年   2篇
  1991年   9篇
  1990年   2篇
  1989年   4篇
  1988年   4篇
  1986年   5篇
  1985年   3篇
  1984年   4篇
  1983年   2篇
  1982年   7篇
  1981年   3篇
  1979年   2篇
  1978年   4篇
  1975年   2篇
  1974年   2篇
  1972年   2篇
  1971年   3篇
  1970年   4篇
  1966年   3篇
排序方式: 共有3215条查询结果,搜索用时 15 毫秒
991.
Guided Fine‐Needle Aspiration Cytology (FNAC) as the first line investigation is not only useful in diagnosis of space occupying lesions but can also help in choosing appropriate management. This technique is most useful in diagnosing metastasis but is also helpful in excluding malignancy in some cases. Aim of this study is to analyze the spectrum of cytological diagnosis, adequacy, and clinicoradiological correlation of guided FNAC. The study was carried out in the departments of pathology and radiology for a period from January 2000 to November 2011. All the data were retrieved from hospital medical record section and departmental data bank and were analyzed. We have performed a total of 500 FNACs, including 234 under CT guidance and 266 under USG guidance. Among the CT‐guided FNACs, 87.6% (205 cases) had adequate material which included 152 malignant cases, 38 inflammatory cases and 15 benign cases. Among the cases under USG, 91.7% (244 cases) had adequate material comprising of 112 malignant cases, 44 inflammatory cases, and 88 benign lesions. It was noted that increased number of inadequate aspirate was from lesions with smaller size and increased depth. Out of total 264 malignant cases diagnosed on FNAC, 160 cases were identified as malignant on clinical and radiological findings. Guided FNAC is useful in deep seated lesions as well as in suspicious superficial lesions and is a safe diagnostic tool. If performed properly and correlated well with clinical and radiological findings, FNAC provides correct diagnosis in most cases. Diagn. Cytopathol. 2013;41:1052–1062. © 2012 Wiley Periodicals, Inc.  相似文献   
992.
Background: Whereas the effect of imageability on lexical access has received attention in normal monolingual individuals and in individuals with aphasia, its effect on normal bilingual access and in bilingual aphasia has not been systematically addressed.Aim: The goal of the present experiment was to examine the effects of imageability in normal bilingual adults and in one patient with bilingual aphasia by addressing the following questions: (a) Is there a difference in language performance in early L2 bilinguals? (b) Is there a difference between concrete and abstract words across both languages? (c) Is there a difference between accuracy on a naming to definition task and semantic priming task across language and imageability?Methods & Procedures: A total of 15 normal Spanish–English bilingual adults and 1 bilingual aphasic individual performed two tasks – a naming to definition task and a semantic priming task in English and in Spanish. The targets in both tasks were either concrete or abstract nouns and the words were translation equivalents in the two languages. Naming accuracy in both languages and for both levels of imageability was measured during the naming to definition task. Mean reaction times and accuracy rates to judge relatedness of word pairs on the semantic priming task were also measured.Results: Results indicated that across tasks, performance was better in English than in Spanish, indicating an English dominance in the normal bilingual adults, although performance was the same across languages in the aphasic patient. Across tasks and languages, responses were faster and more accurate for concrete words than abstract words. Finally, retrieval of abstract words was significantly more difficult during naming to definition than during semantic priming, reflecting a processing difference between concrete and abstract words in retrieval of their respective phonological forms.Conclusions: These results highlight differences between concrete and abstract words in conceptual/semantic representations and phonological retrieval that are notably consistent across both languages in a bilingual individual. Data from the one bilingual aphasic individual suggest the possibility of a systematic deterioration of the normal bilingual language system.  相似文献   
993.
Swathi Kiran 《Aphasiology》2013,27(2):231-261
Background: Edmonds and Kiran (2006 Edmonds, L. and Kiran, S. 2006. Effect of semantic based treatment on cross linguistic generalisation in bilingual aphasia.. Journal of Speech, Language and Hearing Research, 49: 729748. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]) reported that training lexical retrieval in one language resulted in within‐language and cross‐language generalisation in three bilingual (English–Spanish) patients with aphasia.

Aims: The present experiment continues this line of research, repeating a similar procedure with new patients and examining a broader range of factors that may affect generalisation patterns.

Methods & Procedures: Four participants (two Spanish–English and two French–English speakers) with anomia post CVA received a semantic feature‐based treatment aimed at improving naming of English or Spanish/French nouns. Using a multiple baseline design, generalisation to untrained semantically related and unrelated items in each language was measured during periods of therapy first in one language, then in the other.

Outcomes & Results: All patients improved their naming of the trained items in the trained language, although to varying degrees. Within‐language generalisation to semantically related items occurred in two Spanish–English patients and one French–English patient. Cross‐language generalisation to translations and semantically related items occurred only for one French–English patient.

Conclusions: The impact of the intervention is very clear. The semantic feature‐based practice is linked to the gains made, and accounts for the predominance of semantic naming errors after treatment. Possible explanations for the different patterns of generalisation are considered in terms of the various factors including each patient's pre‐stroke language proficiency, age of acquisition of each language, post‐stroke level of language impairment, and type and severity of aphasia.  相似文献   
994.
In the present study, novel dermacozine-1-carboxamides (8a–8n) were synthesized and screened for their in vitro cytotoxic activity against three different cancer cell lines: MCF-7 (breast cancer), A-549 (lung cancer) and DU145 (prostate cancer). All the compounds showed more efficiency against the DU145 cell line than against the MCF-7 and A-549 cell lines. Furthermore, 8a (CTC50: 7.02 μM) and 8l (CTC50: 6.32 μM) have been found to be more effective against the DU145 cells as they arrest the cell cycle at the G2/M phase by interfering with tubulin polymerization; these results indicate that these compounds act as potential anti-cancer agents by inhibiting tubulin polymerization.

In the present study, novel dermacozine-1-carboxamides (8a–8n) were synthesized and screened for their in vitro cytotoxic activity against three different cancer cell lines: MCF-7 (breast cancer), A-549 (lung cancer) and DU145 (prostate cancer).  相似文献   
995.
Farber lipogranulomatosis is a rare autosomal recessive lysosomal storage disorder caused by mutations in the ASAH1 gene. In the largest ever study, we identified and characterized ASAH1 mutations from 11 independent Farber disease (FD) families. A total of 13 different mutations were identified including 1 splice, 1 polypyrimidine tract (PPT) deletion and 11 missense mutations. Eleven mutations were exclusive to the Indian population. The IVS6+4A>G splice and IVS5‐16delTTTTC PPT deletion mutations resulted in skipping of exon 6 precluding thereby the region responsible for cleavage of enzyme precursor. A missense mutation (p.V198A) resulted in skipping of exon 8 due to inactivation of an exonic splicing enhancer (ESE) element. This is the first report of mutations affecting PPT and ESE in the ASAH1 gene resulting in FD.  相似文献   
996.

Objectives

This qualitative study examines performance bias, i.e. unintended differences between groups, in the context of a weight loss trial in which a novel patient counseling program was compared to usual care in general practice.

Methods

14/381 consecutive interviewees (6 intervention group, 8 control group) within the CAMWEL (Camden Weight Loss) effectiveness trial process study were asked about their engagement with various features of the research study and a thematic content analysis undertaken.

Results

Decisions to participate were interwoven with decisions to change behavior, to the extent that for many participants the two were synonymous. The intervention group were satisfied with their allocation. The control group spoke of their disappointment at having been offered usual care when they had taken part in the trial to access new forms of help. Reactions to disappointment involved both movements toward and away from behavior change.

Conclusion

There is a prima facie case that reactions to disappointment may introduce bias, as they lead the randomized groups to differ in ways other than the intended experimental contrast.

Practice implications

In-depth qualitative studies nested within trials are needed to understand better the processes through which bias may be introduced.  相似文献   
997.

Introduction:

Management of bone loss is a challenge in revision total hip arthroplasty (THA). A retrospective review was performed to study the use of uncemented distal locked prosthesis in cases with proximal femoral bone loss.

Materials and Methods:

Uncemented stems with distal interlocking were used in 65 hips during revision THAs with 38 hips having Paprosky IIIB/IV defects between January 1998 and February 2004. There were 48 males and 17 females in the study with an average age of 53 years (range 30-80 years). Radiographic and clinical outcome evaluation using the Harris hip score (HHS) were performed.

Results:

An improvement in HHS (mean: 33 points) was observed at final followup (mean: 9 years). Regeneration of proximal bone stock was observed without signs of loosening or subsidence and none of the stems were revised. Three patients developed recurrent dislocation while one had a stem subsidence of 1cm following removal of interlocking bolts.

Conclusion:

Uncemented distal locked prosthesis provide adequate stability in revision THA, aiding the reconstruction of bony deficiencies while avoiding the disadvantages of fully porous or cemented implants.  相似文献   
998.
Mitotic counting is often used for classification, grading and prognosis of tumors. The count usually stands as a decision point for treatment as well. The easiest way of counting the number of mitoses is done by screening routine H&E stained slides. However, for proper mitotic counting, certain strict protocols should be taken into consideration. This study on 30 cases of different grades of oral squamous cell carcinoma was undertaken to determine the interobserver variations in two different groups: Group1 (A1, A2), who were given certain criteria to be followed during the counting of the mitotic figures and group 2 investigators (B1, B2) who were unaware of such criteria. The paired t-test gives a correlation of 0.988 and a significant difference of 0.000 between the two investigators in group 1. The correlation was 0.650 with a significant difference of 0.058 between two investigators in-group 2, indicating that group 1 observers exhibit good interobserver agreement. The results emphasize that following of strict protocols are of great help in determining the accuracy of mitotic counting. Keywords: Mitotic figures, Mitotic counting, Squamous cell carcinoma. How to cite this article: Yadav KS, Gonuguntla S, Ealla KKR, Velidandla SR, Reddy CRC, Prasanna MD, Bommu SR. Assessment of Interobserver Variability in Mitotic Figure Counting in Different Histological Grades of Oral Squamous Cell Carcinoma. J Contemp Dent Pract 2012;13(3):339-344. Source of support: Nil Conflict of interest: None declared.  相似文献   
999.
This article describes the treatment of an adult male with vertical maxillary excess, excessive gingival display on smiling, a convex profile, proclined upper and lower incisors, and crowded lower anteriors with severe lip incompetence. The therapy included stages: (1) Pre surgical orthodontics- leveling and aligning of the maxillary and mandibular arch with closure of all extraction spaces. (2) Surgical phase-Lefort I osteotomy for superior maxillary impaction, 5 mm of anterior and 3 mm of posterior impaction ofmaxilla was done. (3) Post surgical orthodontics for finishing and detailing. The treatment lasted 16 months; improved facial esthetics significantly; and resulted in a normal occlusion, overjet, and overbite.  相似文献   
1000.

Background

Risk of adhesive small-bowel obstruction (SBO) is high following open colorectal surgery. Laparoscopic surgery may induce fewer adhesions; however, the translation of this advantage to a reduced rate of bowel obstruction has not been well demonstrated. This study evaluates whether SBO is lower after laparoscopic compared with open colorectal surgery.

Methods

Patients who underwent laparoscopic abdominal colorectal surgery, without any previous history of open surgery, from 1998 to 2010 were identified from a prospective laparoscopic database. Details regarding occurrence of symptoms of SBO (colicky abdominal pain; nausea and/or vomiting; constipation; abdominal distension not due to infection or gastroenteritis), admissions to hospital with radiological findings confirming SBO, and surgery for obstruction after the laparoscopic colectomy were obtained by contacting patients and mailed questionnaires. Patients undergoing open colorectal surgery for similar operations during the same period and without a history of previous open surgery also were contacted and compared with the laparoscopic group for risk of obstruction.

Results

Information pertaining to SBO was available for 205 patients who underwent an elective laparoscopic procedure and 205 similar open operations. The two groups had similar age, gender, and sufficiently long duration of follow-up. Despite a significantly longer duration of follow-up for the laparoscopic group, admission to hospital for SBO was similar between groups. Patients who underwent laparoscopic surgery also had significantly lower operative intervention for SBO (8% vs. 2%, p = 0.006).

Conclusions

Although the rate of SBO was similar after laparoscopic and open colorectal surgery, the need for operative intervention for SBO was significantly lower after laparoscopic operations. These findings especially in the context of the longer follow-up for laparoscopic patients suggests that the lower incidence of adhesions expected after laparoscopic surgery likely translates into long-term benefits in terms of reduced SBO.  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