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   5524篇
  免费   316篇
  国内免费   31篇
耳鼻咽喉   33篇
儿科学   185篇
妇产科学   120篇
基础医学   733篇
口腔科学   144篇
临床医学   385篇
内科学   1111篇
皮肤病学   93篇
神经病学   395篇
特种医学   256篇
外科学   695篇
综合类   27篇
预防医学   609篇
眼科学   288篇
药学   398篇
中国医学   6篇
肿瘤学   393篇
  2023年   26篇
  2022年   51篇
  2021年   122篇
  2020年   63篇
  2019年   101篇
  2018年   117篇
  2017年   98篇
  2016年   85篇
  2015年   123篇
  2014年   137篇
  2013年   165篇
  2012年   297篇
  2011年   301篇
  2010年   165篇
  2009年   136篇
  2008年   277篇
  2007年   282篇
  2006年   313篇
  2005年   298篇
  2004年   314篇
  2003年   283篇
  2002年   276篇
  2001年   212篇
  2000年   180篇
  1999年   164篇
  1998年   69篇
  1997年   54篇
  1996年   68篇
  1995年   37篇
  1994年   31篇
  1993年   18篇
  1992年   94篇
  1991年   74篇
  1990年   72篇
  1989年   82篇
  1988年   91篇
  1987年   59篇
  1986年   61篇
  1985年   58篇
  1984年   52篇
  1983年   26篇
  1979年   25篇
  1978年   30篇
  1977年   18篇
  1976年   24篇
  1975年   21篇
  1974年   22篇
  1973年   34篇
  1972年   18篇
  1968年   18篇
排序方式: 共有5871条查询结果,搜索用时 234 毫秒
61.
Unilateral obstruction of a duplicate uterus is very rare. The current recommendation for its correction involves transmural incision of the uterine muscle. A method is presented here that was successfully applied in one patient suffering from this anomaly, using sonographically guided hysteroscopy. This method obviated the need for an extensive operation.  相似文献   
62.
Lexical priming deficits as a function of age   总被引:2,自引:0,他引:2  
The effects of age on implicit memory were assessed in elderly young adults using 2 priming procedures. Subjects also completed the WAIS-R, 3 tests to assess frontal lobe function, and 2 recall and 2 recognition tests of explicit memory. In Experiment 1, subjects were exposed to the low-frequency member of a homophone pair in a test purported to assess general knowledge. Subsequently, subjects completed a spelling test that contained the previously presented homophones to assess priming. Young subjects demonstrated priming (p less than .01). Elderly subjects demonstrated a high baseline that may have obscured priming. In Experiment 2, subjects from each decade of life from the 20s through the 80s were given a word-stem completion test of priming. All age conditions demonstrated an effect of priming (p less than .01). However, subjects in their 70s and 80s demonstrated lower priming scores (p less than .05). Elderly subjects were also impaired on immediate-and delayed-recall tests. These results suggest an age-related decline in both implicit and explicit memory.  相似文献   
63.
Immediate hypersensitivity to penicillins. Studies on Italian subjects   总被引:4,自引:5,他引:4  
The IgE response, the involvement of the different penicillins available for therapeutic use, and the specificity of the IgE antibodies found in a group of penicillin-allergic subjects from Italy were studied. Thirty subjects with a history of allergic reactions to penicillins were studied. In vivo and in vitro specific IgE antibodies were determined to different penicillin determinants. Fifteen subjects developed anaphylactic responses and the remainder urticaria and angioedema. The drug most frequently involved in the patients' allergic reactions was ampicillin (AMP). The benzylpenicilloyl (BPO) skin test was positive in 16 (53.3%) patients, whereas 23 (76.6%) patients were positive to minor determinant mixture (MDM), benzylpenicillin (PG), AMP, or amoxicillin (AX). When classified according to initial reaction type, most anaphylactic patients (93.3%) were associated with minor determinant reactivity, whereas most urticaria patients (80%) reacted to BPO. RAST results for the anaphylactic and urticaria subgroups were similar. RAST inhibition showed that most sera contained highly cross-reactive IgE antibodies. There was evidence of a specific response to AX and PG (one patient each). These data show that in a population of penicillin-allergic patients from Italy, AMP was the main drug inducing the allergic reaction. In skin tests and RAST, patients exhibited heterogeneous IgE responses with little indication of specific reactivity to AMP.  相似文献   
64.
Oleoylethanolamide (OEA) is a naturally occurring bioactive lipid belonging to the family of N-acylethanolamides. A variety of beneficial effects have been attributed to OEA, although the greater interest is due to its potential role in the treatment of obesity, fatty liver, and eating-related disorders. To better clarify the mechanism of the antiadipogenic effect of OEA in the liver, using a lipidomic study performed by 1H-NMR, LC-MS/MS and thin-layer chromatography analyses we evaluated the whole lipid composition of rat liver, following a two-week daily treatment of OEA (10 mg kg−1 i.p.). We found that OEA induced a significant reduction in hepatic triacylglycerol (TAG) content and significant changes in sphingolipid composition and ceramidase activity. We associated the antiadipogenic effect of OEA to decreased activity and expression of key enzymes involved in fatty acid and TAG syntheses, such as acetyl-CoA carboxylase, fatty acid synthase, diacylglycerol acyltransferase, and stearoyl-CoA desaturase 1. Moreover, we found that both SREBP-1 and PPARγ protein expression were significantly reduced in the liver of OEA-treated rats. Our findings add significant and important insights into the molecular mechanism of OEA on hepatic adipogenesis, and suggest a possible link between the OEA-induced changes in sphingolipid metabolism and suppression of hepatic TAG level.  相似文献   
65.
Altered circulating levels of free fatty acids (FFAs), namely short chain fatty acids (SCFAs), medium chain fatty acids (MCFAs), and long chain fatty acids (LCFAs), are associated with metabolic, gastrointestinal, and malignant diseases. Hence, we compared the serum FFA profile of patients with celiac disease (CD), adenomatous polyposis (AP), and colorectal cancer (CRC) to healthy controls (HC). We enrolled 44 patients (19 CRC, 9 AP, 16 CD) and 16 HC. We performed a quantitative FFA evaluation with the gas chromatography–mass spectrometry method (GC–MS), and we performed Dirichlet-multinomial regression in order to highlight disease-specific FFA signature. HC showed a different composition of FFAs than CRC, AP, and CD patients. Furthermore, the partial least squares discriminant analysis (PLS-DA) confirmed perfect overlap between the CRC and AP patients and separation of HC from the diseased groups. The Dirichlet-multinomial regression identified only strong positive association between CD and butyric acid. Moreover, CD patients showed significant interactions with age, BMI, and gender. In addition, among patients with the same age and BMI, being male compared to being female implies a decrease of the CD effect on the (log) prevalence of butyric acid in FFA composition. Our data support GC–MS as a suitable method for the concurrent analysis of circulating SCFAs, MCFAs, and LCFAs in different gastrointestinal diseases. Furthermore, and notably, we suggest for the first time that butyric acid could represent a potential biomarker for CD screening.  相似文献   
66.
Microsatellite replication errors (RERs), consisting in random tumour-associated allele contractions or expansions, represent a frequent genetic alteration in gastric cancer and appear to be associated with important clinicopathologic parameters. To verify the role of microsatellite instability in the initial phases of gastric carcinogenesis, we analysed the status of II microsatellites in paired microdissected samples of tumour and unaffected mucosa from 30 cases of early gastric carcinoma. Fifteen tumours (50%) demonstrated RERs: these included 7 cases with RERs at one locus and 8 cases with RERs at 2 or more loci. Cases with 2 or more RERs were more frequent among intramucosal tumours, compared to tumours with submucosal spread (43% vs. 12%) and among tumours staged T1NOMx, compared to tumours staged T1N1Mx (35% vs. 0%). RER-positive microsatellite typings were statistically more frequent among tumours with intramucosal extension, lower stage (T1NOMx) and excavated growth pattern (macroscopic type III), compared to tumours with submucosal extension, higher stage (T1N1Mx) and elevated, flat or depressed growth patterns (macroscopic types IIa-IIb-IIc respectively). The above findings indicate that microsatellite instability occurs early in the progression of sporadic gastric cancer and tends to be associated with good prognostic indicators.  相似文献   
67.
68.
69.
BACKGROUND: The electrically stimulated gracilis neoanal sphincter was initially developed to treat refractory incontinence. Good early results were reported from the two centres that pioneered the technique. The aim of this study was to assess the operation in a prospective multicentre setting. METHODS: The procedure was performed on 64 patients from seven centres worldwide and was performed in stages. All patients were evaluated clinically and manometrically before and after operation. RESULTS: There was a high incidence of infective and hardware-related complications. At a median of 10 months following closure of the defunctioning stoma 56 per cent had experienced a good functional result. The major functional problems comprised evacuatory difficulties experienced by 25 per cent. CONCLUSION: The technique is effective in treating otherwise refractory incontinence. It is, however, a complex procedure and the morbidity rate may be high, particularly during the learning curve, factors that necessitate careful patient selection. Presented to the Association of Surgeons of Great Britain and Ireland in Bournemouth, UK, April 1997 and the European Council of Coloproctology in Edinburgh, UK, June 1997; and published in abstract form as Br J Surg 1997; 88(Suppl): 39 and Int J Colorectal Dis 1997; 12: 144  相似文献   
70.
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