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   4527篇
  免费   214篇
  国内免费   51篇
耳鼻咽喉   77篇
儿科学   55篇
妇产科学   25篇
基础医学   566篇
口腔科学   79篇
临床医学   322篇
内科学   1445篇
皮肤病学   75篇
神经病学   360篇
特种医学   114篇
外科学   610篇
综合类   48篇
预防医学   131篇
眼科学   60篇
药学   216篇
中国医学   9篇
肿瘤学   600篇
  2023年   50篇
  2022年   92篇
  2021年   155篇
  2020年   84篇
  2019年   131篇
  2018年   127篇
  2017年   87篇
  2016年   122篇
  2015年   110篇
  2014年   158篇
  2013年   168篇
  2012年   239篇
  2011年   305篇
  2010年   154篇
  2009年   116篇
  2008年   210篇
  2007年   233篇
  2006年   199篇
  2005年   223篇
  2004年   210篇
  2003年   213篇
  2002年   173篇
  2001年   136篇
  2000年   141篇
  1999年   117篇
  1998年   48篇
  1997年   39篇
  1996年   32篇
  1995年   22篇
  1994年   19篇
  1993年   17篇
  1992年   58篇
  1991年   61篇
  1990年   63篇
  1989年   54篇
  1988年   50篇
  1987年   51篇
  1986年   37篇
  1985年   48篇
  1984年   27篇
  1983年   21篇
  1980年   12篇
  1979年   16篇
  1977年   12篇
  1976年   11篇
  1972年   16篇
  1971年   11篇
  1970年   12篇
  1968年   15篇
  1967年   9篇
排序方式: 共有4792条查询结果,搜索用时 15 毫秒
51.
Although the osteosarcoma is considered to be among the most chemosensitive malignancies and preoperative chemotherapy is commonly applied, an appreciable proportion of cases are in fact quite insensitive. Predictive markers for chemosensitivity are therefore desirable in order to develop effective treatment strategies. Thirty-two cases of conventional osteosarcomas treated at the Cancer Institute Hospital, Tokyo, were analyzed. The sensitivity to preoperative chemotherapy was investigated with reference to loss of heterozygosity (LOH) at the 17p13 ( p 53) and 13q14 ( Rb ) loci and expression of the cell-cycle associated proteins, p53, Rb, p21/Waf-1, mdm-2 and Ki-67, as detected immunohistochemically. LOH was detected by analyzing polymerase chain reaction products at marker microsatellite loci. The efficacy of chemotherapy was evaluated both radiologically and histologically. LOH at p 53 or Rb loci was seen in 54% (13/24) and 58% (14/24) of cases, respectively. Only 15% of osteosarcomas with LOH at the p 53 locus were sensitive to preoperative chemotherapy, as compared to 64% of tumors without such loss ( P <0.05). A similar but much less distinct tendency was observed with LOH at the Rb locus. No relationship was evident between chemosensitivity and immunohistochemical staining patterns for p53, Rb, p21/Waf-1, mdm-2 or Ki-67. The results suggest that p 53 gene deletion, but not the other parameters investigated, may be useful for predicting chemoresistance of osteosarcomas.  相似文献   
52.
To explore the possible histogenesis of superficially spreading carcinoma of the esophagus, the clinicopathological features of these tumors (n = 44) were compared with those of ordinary superficial carcinoma (n = 163). Tumors of a heterogeneous histological type and having in situ carcinoma components were significantly more common (P < .05), and the number of residual squamous islands was significantly greater (P < 0.05) in the former group than the latter. Furthermore, the tumor size was not different among in situ, intramucosal, and submucosal carcinomas of the former, whereas the tumors became larger according to the depth of invasion in the latter group. These results indicate that the collision of multiple simultaneously developing superficial tumors is a plausible histogenesis of superficially spreading carcinoma of the esophagus.  相似文献   
53.
We evaluated somatic genetic alterations in the kinase domain of the EGFR gene in the tumors of 219 non-small cell lung cancer patients of primarily Caucasian and African American origins. We identified 26 patients (12%) whose tumors had a mutation in the EGFR gene, and 11 (5%) patients carried novel genomic variations consistent with germ-line polymorphisms. All but one mutation were identified in Caucasian patients affected with adenocarcinoma. EGFR mutations were more frequent in women and in nonsmokers, but a significant portion of the affected patients were men (12 of 26) and current or past smokers accounted for half of the patients affected (13 of 26). Screening subjects with EGFR mutations may identify patients whose tumors could respond to targeted therapy using tyrosine kinase inhibitors.  相似文献   
54.
We report the case of a 52-year-old woman with hepatitis B virus (HBV) reactivation during treatment for chronic graft vs. host disease (GVHD) after peripheral bone marrow transplantation (PBSCT) to treat chronic myelocytic leukemia. She was given cyclosporine and prednisolone orally to treat chronic GVHD after PBSCT. Liver dysfunction first developed 25 months after transplantation with the appearance of hepatitis B s antigen (HBsAg), hepatitis B e antigen (HBeAg), and elevation of HBV-DNA up to 4.5 log copies/ml. Retrospective examination of her serum before PBSCT proved negative for HBsAg and HBeAg, and positive for anti-HBsAg, anti-HBeAg, anti-hepatitis B core antigen, and HBV-DNA (2.7 log copies/ml), showing that she was in a state of occult HBV infection. Nucleotide sequences of the HBV genome obtained from her serum showed no core promoter mutations at nt 1762 and 1764 and no pre-core mutation at nt 1896. Polymerase chain reaction-restriction fragment length polymorphism showed that she was infected with HBV genotype B. The administration of lamivudine, a nucleoside analog, improved her liver function and reduced HBV-DNA replication. We conclude that antiviral agents, such as lamivudine, are effective for treating hepatitis B reactivation during immunosuppressive treatment, such as for GVHD. The administration of a nucleoside analog before transplantation should also be considered in the light of HBV genotypes and mutations, even if HBsAg was negative and the viral load was low before transplantation.  相似文献   
55.
A. Kanda  K. Noda  W. Saito  S. Ishida 《Diabetologia》2012,55(11):3104-3113

Aims/hypothesis  

The renin–angiotensin system (RAS) potentially has a role in the development of end-organ damage, and tissue RAS activation has been suggested as a risk factor for diabetic retinopathy. We have recently shown significant involvement of (pro)renin receptor ([P]RR) in retinal inflammation in a rodent model of early diabetes. In this study we aim to elucidate the (P)RR-associated pathogenesis of fibrovascular proliferation, a late-stage angiogenic complication in human diabetic retinopathy.  相似文献   
56.
Increasing evidence indicates that microRNAs (miRNAs) participate in almost every step of cellular processes and are often aberrantly expressed in human cancer. Therefore, the discovery of miRNAs may provide a new and powerful tool for understanding the mechanism and treatment of carcinogenesis. The aim of this study was to investigate the functional significance of miR-100 and to identify its possible target genes in osteosarcoma (OS) cells. Here, we found that expression level of miR-100 was significantly decreased in osteosarcoma tissues in comparison with the adjacent normal tissues. The enforced expression of miR-100 was able to inhibit cell proliferation in Saos-2 and MG63 cells, while its antisense oligonucleotides (antisense miR-100) promoted cell proliferation. Moreover, our results further revealed that expression of Cyr61, an extracellular matrix-associated growth factor, was negatively regulated by miR-100. Therefore, we consider that miR-100 acts as a tumor suppressor for osteosarcoma. It may provide novel diagnostic and therapeutic options for human osteosarcoma in the future.  相似文献   
57.
Sarcoidosis is a multi‐systemic disease of unknown etiology that results in the development of non‐caseating epithelioid granulomas. The liver is the third most frequently involved organ after the lymph nodes and the lungs. Most cases of liver sarcoidosis do not present with symptoms and involve minimal liver dysfunction, but some cases display progression to portal hypertension and liver cirrhosis, and finally to liver failure. The mechanism and the risk of progression in liver sarcoidosis are still unknown because of the diagnostic difficulty associated with this condition, and because follow‐up examinations can only be done in an invasive manner. Here, we present an informative case of liver sarcoidosis with rapid progression of esophagogastric varices. Four months prior to the definitive diagnosis, no signs of varices were observed on endoscopy, and developmentof esophagogastric varices, rapid progression, and eventual rupture occurred in a short period of time. A liver biopsy, carried out after endoscopic sclerotherapy, revealed that granulomas primarily affected the portal area without fibrotic and cirrhotic changes, which is considered a primary cause of portal hypertension and esophagogastric varices. Following the liver biopsy, the patient was given systemic steroids and is currently receiving outpatient care. Thus, we should consider the possibility that liver sarcoidosis, even in the absence of cirrhotic changes, can cause serious events such as esophagogastric variceal rupture following rapid progression as a result of portal hypertension.  相似文献   
58.
IntroductionAtrophic vaginitis is a common occurrence, particularly among postmenopausal women; however, few seek or receive treatment. One therapeutic solution is topically applied products. Estrogen‐based treatments have been shown to be effective; however, many patients are reluctant to use such formulations due to health concerns, hence the need to assess the efficacy of acceptable alternatives.AimThis multicenter, randomized, controlled, open‐label, parallel‐group clinical trial set out to evaluate the efficacy and safety of hyaluronic acid vaginal gel to treat vaginal dryness compared with estriol cream in postmenopausal women.MethodsOne hundred forty‐four subjects were randomized, 72 to the test group treated with hyaluronic acid vaginal gel (Hyalofemme) and 72 to the control group treated with estriol cream (Ovestin). Treatment in both groups was applied by means of a device once every 3 days for a total of 10 applications over 30 days.Main Outcome MeasuresEfficacy was measured by grading vaginal dryness and three other vaginal symptoms on a visual analog scale. Safety assessments included vital signs, laboratory examinations of the vaginal microecosystem, vaginal pH value, vaginal B ultrasound, and incidence of adverse events. Assessments were performed at baseline, by telephone after the third application, and at the final visit.ResultsBoth hyaluronic acid vaginal gel and estriol cream can significantly improve the clinical symptoms of vaginal dryness in postmenopausal women, with improvement rate of 84.44% and 89.42%, respectively, after 10 applications, without statistically significant difference between them.ConclusionBoth hyaluronic acid vaginal gel and estriol cream are effective in the treatment of vaginal dryness. Hyaluronic acid vaginal gel may be considered as a valid alternative to estrogen‐based treatments in relieving the symptoms of vaginal dryness.  相似文献   
59.
60.
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