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   1521篇
  免费   76篇
  国内免费   8篇
耳鼻咽喉   45篇
儿科学   104篇
妇产科学   93篇
基础医学   166篇
口腔科学   60篇
临床医学   122篇
内科学   326篇
皮肤病学   58篇
神经病学   172篇
特种医学   31篇
外科学   185篇
综合类   18篇
预防医学   45篇
眼科学   29篇
药学   78篇
中国医学   5篇
肿瘤学   68篇
  2024年   1篇
  2023年   10篇
  2022年   25篇
  2021年   38篇
  2020年   25篇
  2019年   25篇
  2018年   39篇
  2017年   36篇
  2016年   46篇
  2015年   55篇
  2014年   82篇
  2013年   101篇
  2012年   137篇
  2011年   111篇
  2010年   58篇
  2009年   72篇
  2008年   103篇
  2007年   128篇
  2006年   130篇
  2005年   111篇
  2004年   90篇
  2003年   73篇
  2002年   47篇
  2001年   11篇
  2000年   14篇
  1999年   5篇
  1998年   5篇
  1997年   4篇
  1996年   6篇
  1995年   3篇
  1994年   3篇
  1993年   2篇
  1992年   2篇
  1991年   4篇
  1986年   1篇
  1984年   1篇
  1978年   1篇
排序方式: 共有1605条查询结果,搜索用时 156 毫秒
11.
The jawbones can be sites of various neoplastic conditions. Given the variety of processes affecting this particular anatomical area, formulation of a precise diagnosis can be challenging to clinicians. Limited jaw movement, pain, and facial asymmetry are common signs among patients, especially those with temporomandibular disorder (TMD). This paper reports a case of primary fibrosarcoma affecting the mandible and surrounding structures in a 14-year-old girl presenting signs and symptoms similar to TMD. Her condition was misdiagnosed, and she was treated for TMD over an extended period before the correct diagnosis was made for fibrosarcoma. The patient underwent surgical resection with postsurgical radiotherapy and chemotherapy and now is being followed up. Although malignant lesions are rare in the temporomandibular joint (TMJ) region, dentists are advised to be aware of the condition and to keep in mind that patients who are admitting for TMD can also possibly be affected from neoplasms. Hence, those patients have to be examined meticulously to avoid misdiagnosis and mistreatment.  相似文献   
12.
Five-day-old Wistar albino rats were injected with kainic acid (KA) or saline i.p. to investigate time-dependent alterations in morphology and number of basic fibroblast growth factor (bFGF) immunoreactive (-ir) astrocytes and neurons in hippocampus at 15, 30, and 90 days after the injections. Sections were stained with cresyl violet for morphological evaluation and bFGF immunohistochemistry was used for quantitative evaluation of bFGF-ir cell density. Fifteen days after KA injection, there was gliosis but no neuronal loss although disorganization in CA1, CA3, CA4 pyramidal layers and neuronal loss were evident 30 and 90 days after the injection. KA injected rats demonstrated significantly increased number of bFGF-ir astrocytes throughout the hippocampus and pyramidal neurons in CA2 after 15 days and decreased number of bFGF-ir cells after 30 and 90 days. The decrease in the number of bFGF-ir astroglia and neurons in long term after KA injection may indicate a decrease in the production of bFGF and/or number of bFGF-ir cells suggesting that protective effects of bFGF may be altered during epileptogenesis in hippocampus.  相似文献   
13.
Molecular genetic methods in the diagnosis of hematologic neoplasms   总被引:3,自引:0,他引:3  
Leukemias and lymphomas are monoclonal neoplasms that arise as a result of molecular abnormalities. These abnormalites are diverse but can be grouped into two general categories, chromosomal translocations that usually result in oncogene activation and inactivation of tumor suppressor genes. Recent advances in our understanding of chromosomal translocations have led to improved classification of leukemias and lymphomas. For example, the t(9;22)(q34;q11) is now considered a defining feature of chronic myeloid leukemia, and the t(2;5)(p23;q35) defines a clinically and biologically unique subset of anaplastic large cell lymphomas. In this review, we focus on chromosomal translocations in hematologic neoplasms and the techniques used for their detection. We also briefly discuss tumor suppressor genes and assessment of clonality in lymphoid neoplasms.  相似文献   
14.
Peripheral T-cell lymphomas (PTCLs) are a heterogeneous group of non-Hodgkin lymphomas with a wide spectrum of clinicopathologic features, and apoptosis mechanisms may have a role in lymphomagenesis. We assessed apoptotic rate (AR) in 112 PTCLs using a tissue microarray developed in our laboratory and a modified terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay. The mean AR was 1.47% +/- 1.38% for the entire group of PTCLs (range, 0.06%-5.15%), and AR varied significantly among different tumor types. In mycosis fungoides, the mean AR was 0.74%; angioimmunoblastic T-cell lymphoma, 1.02%; PTCL, not otherwise specified, 1.38%; cutaneous anaplastic large cell lymphoma (ALCL), 1.41%; anaplastic lymphoma kinase protein (ALK)-negative ALCL, 1.43%; extranodal natural killer/T-cell lymphoma of nasal type, 2.04%; ALK-positive ALCL, 2.95%; and enteropathy-type T-cell lymphoma, 3.06%. Mean AR was higher in PTCL with large cell vs small/medium cell morphologic features (1.66% +/- 1.1% vs 0.99% +/- 1.0%). In a subset of 33 PTCLs, the tissue microarray results comparedfavorably with those obtained in full tissue sections. We conclude that the highest ARs in PTCLs are found in enteropathy-type T-cell lymphoma and ALK-positive ALCL, and that AR can be assessed reliably by using a tissue microarray.  相似文献   
15.
BACKGROUND: Patients with allergic rhinitis and bronchial hyperresponsiveness (BHR) may be at higher risk of developing asthma. OBJECTIVE: To investigate whether reactivity to aeroallergens in skin prick testing (SPT) and serum eosinophil cationic protein levels can be used to predict BHR in allergic rhinitis patients. METHODS: Fifty-nine consecutive patients with allergic rhinitis underwent SPTs using grass, tree, weed, parietaria, Alternaria, Aspergillus, mites, and cat and dog dander extracts. Methacholine challenge tests were performed using spirometry. RESULTS: Methacholine-induced BHR was detected in 23 patients (39%). Of 59 patients, 14 had 1 positive SPT response, 35 had 2 to 4 positive responses, and 10 had more than 4 positive responses. There was a significant inverse correlation between methacholine provocation concentration that caused a decrease in forced expiratory volume in 1 second of 20% (PC20) and the number of positive SPT responses (r = -0.28; P = .03). The BHR-positive patients had a mean of 4 positive SPT responses, whereas BHR-negative patients had a mean of 2.6 (P = .04). Nine BHR-positive patients (39%) and only 1 BHR-negative patient (3%) had more than 4 positive SPT responses (P < .001). There was no correlation between serum eosinophil cationic protein levels and methacholine PC20 doses. There was a strong association between hyperresponsiveness to methacholine and both cat and dog dander sensitivity (P < .001 and P = .001, respectively). CONCLUSIONS: Allergic rhinitis patients with SPT responses to a higher number of allergens are more likely to have BHR. Whether the number of positive SPT responses correlates with the risk of developing asthma in allergic rhinitis patients remains to be determined.  相似文献   
16.
Percutaneous nephrolithotomy in older children   总被引:4,自引:0,他引:4  
PURPOSE: The aim of this study was to evaluate the safety and efficacy of percutaneous nephrolithotomy (PCNL) in pediatric patients, older than 8 years, without any technical and instrumental modifications. METHODS: The authors retrospectively evaluated the data of 16 percutaneously treated kidneys of 14 patients with a mean age of 11 years (range, 8 to 17). The mean stone burden was calculated as 301 mm2 (range, 120-750). Percutaneous accesses were done under fluoroscopic control, and 24F to 30F Amplatz dilators were used depending on patient size. Ultrasonic and laser lithotripsy were performed to fragment calculi. RESULTS: Mean operating time was 111 minutes (range, 60 to 210 min) and no intraoperative or postoperative major complication was observed. Mean hemoglobin drop after the procedure was 1.16 g/dL (range, 0.3 to 2.8). Blood transfusion was required in only 1 patient, and mean postoperative hospitalization was 4.6 days (range, 3 to 10). Stone-free rate was calculated as 69% (11 of 16), but with residual fragments smaller than 4 mm, the success rate becomes 100% at patient's discharge. CONCLUSIONS: PCNL is an effective and safe form of therapy in pediatric stone disease. Especially in older children the use of the same instruments and technique as in adults may achieve equal results without any increased risk of possible morbidity and need of blood transfusion.  相似文献   
17.
OBJECTIVES: To determine the differences in and factors related to satisfaction between barrier (male condom) and non-barrier method users. METHODS: A semi-structured questionnaire was used for collecting data for this cross-sectional survey. The questionnaires were completed via one-on-one interviews by the researchers. The study group was selected using stratified random sampling. Exclusion criteria were, being unmarried, pregnant, in postmenopausal status and using traditional methods. A total of 434 currently married women using modern contraceptive methods participated in the study. Contraceptive users were dichotomized into two groups as non-barrier method users and barrier method users. RESULTS: About half of the participants (n = 191, 44%) were barrier method users. Their mean age was 33.7 +/- 7.3 years, 66.6% (n = 131) were well educated and reported significantly less pregnancies, given births, living children and abortions (reproductive history events) than non-barrier users. Barrier method users were significantly more likely to be satisfied with their contraceptive method of choice (OR: 2.4; 95% CI 1.2-5.2). Among barrier method users, deciding the type of the contraceptive method themselves had significant effect on satisfaction.CONCLUSION: In our study, satisfaction was mostly affected by heavy side effects and health risks of the methods resulting in less satisfaction with the contraceptive method among non-barrier method users. Other factors which may influence satisfaction deserve further investigation.  相似文献   
18.
Abstract

Synthetic micro/nanomotors (MNMs) are novel, self-propelled nano or microscale devices that are widely used in drug transport, cell stimulation and isolation, bio-imaging, diagnostic and monitoring, sensing, photocatalysis and environmental remediation. Various preparation methods and propulsion mechanisms make MNMs “tailormade” nanosystems for the intended purpose or use. As the one of the newest members of nano carriers, MNMs open a new perspective especially for rapid drug transport and gene delivery. Although there exists limited number of in-vivo studies for drug delivery purposes, existence of in-vitro supportive data strongly encourages researchers to move on in this field and benefit from the manoeuvre capability of these novel systems. In this article, we reviewed the preparation and propulsion mechanisms of nanomotors in various fields with special attention to drug delivery systems.  相似文献   
19.
Endometrial carcinoma (EnCa) is the most common invasive gynaecologic carcinoma. Over 85% of EnCa are classified as endometrioid, expressing steroid hormone receptors and mostly involving pathological prestages. Human endogenous retroviruses (ERV) are chromosomally integrated genes, account for about 8% of the human genome and are implicated in the etiology of carcinomas. The majority of ERV envelope (env) coding genes are either not present or not consistently represented between common gene expression microarrays. The aim of this study was to analyse the absolute gene expression of all known 21 ERV env genes including 19 codogenic and two env genes with premature stop codons in EnCa, endometrium as well as in hyperplasia and polyps. For EnCa seven env genes had high expression with >200 mol/ng cDNA (e.g. envH1-3, Syncytin-1, envT), two middle >50 mol/ng cDNA (envFc2, erv-3) and 12 low <50 mol/ng cDNA (e.g. Syncytin-2, envV2). Regarding tumor parameters, Syncytin-1 and Syncytin-2 were significantly over-expressed in advanced stage pT2 compared to pT1b. In less differentiated EnCa Syncytin-1, erv-3, envT and envFc2 were significantly over-expressed. Syncytin-1, Syncytin-2 and erv-3 were specific to glandular epithelial cells of polyps, hyperplasia and EnCa using immunohistochemistry. An analysis of 10 patient-matched EnCa with endometrium revealed that the ERV-W 5'' long terminal repeat regulating Syncytin-1 was hypomethylated, including the ERE and CRE overlapping MeCP2 sites. Functional analyses showed that 10 env genes were regulated by methylation in EnCa using the RL95-2 cell line. In conclusion, over-expressed env genes could serve as indicators for pathological pre-stages and EnCa.  相似文献   
20.
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