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:      
  示例: 沙坡头地区,人工植被区,变化  检索词用空格隔开表示必须包含全部检索词,用“,”隔开表示只需满足任一检索词即可!
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   11366篇
  免费   205篇
  国内免费   35篇
耳鼻咽喉   137篇
儿科学   275篇
妇产科学   217篇
基础医学   1622篇
口腔科学   352篇
临床医学   1085篇
内科学   2219篇
皮肤病学   182篇
神经病学   1270篇
特种医学   181篇
外科学   944篇
综合类   40篇
一般理论   5篇
预防医学   1171篇
眼科学   112篇
药学   937篇
  3篇
中国医学   57篇
肿瘤学   797篇
  2024年   104篇
  2023年   109篇
  2022年   251篇
  2021年   435篇
  2020年   280篇
  2019年   374篇
  2018年   383篇
  2017年   274篇
  2016年   277篇
  2015年   335篇
  2014年   504篇
  2013年   600篇
  2012年   927篇
  2011年   976篇
  2010年   485篇
  2009年   442篇
  2008年   697篇
  2007年   746篇
  2006年   617篇
  2005年   608篇
  2004年   562篇
  2003年   480篇
  2002年   443篇
  2001年   49篇
  2000年   32篇
  1999年   55篇
  1998年   87篇
  1997年   73篇
  1996年   48篇
  1995年   47篇
  1994年   47篇
  1993年   38篇
  1992年   25篇
  1991年   21篇
  1990年   19篇
  1989年   12篇
  1988年   13篇
  1987年   9篇
  1986年   7篇
  1985年   12篇
  1984年   13篇
  1983年   10篇
  1982年   19篇
  1981年   11篇
  1980年   10篇
  1979年   8篇
  1978年   6篇
  1977年   3篇
  1976年   6篇
  1974年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
The aim of this study was to evaluate the applicability of different calibration approaches in trichothecenes analysis from wheat flour. Concretely eight trichothecenes (five type B trichothecenes and three type A trichothecenes) were analyzed by matrix solid-phase dispersion (MSPD) and liquid chromatography–tandem mass spectrometry (LC–MS/MS). In the first set of experiments the presence of matrix effects was evaluated; values ranged between 59% and 79%. In the second set of experiments, solutions to compensate these signal suppressions were examined. Different calibration methods showed to tackle matrix effects obtaining values between 69% and 85% for external matrix matched calibration and values from 76% to 111% and from 78% to 108% by analog and deuterated internal standard calibrations, respectively. Trueness of the method was studied using quality control material and certificated reference material (DON 1062 ± 110 μg kg−1). The values were compared by matrix-matched, analog internal standard (deepoxydeoxynivalenol (DOM-1)) and deuterated internal standard (DON-d1).  相似文献   
32.
33.
American cutaneous leishmaniasis (ACL) caused by Leishmania (Viannia) braziliensis is a neglected disease of humans in the New World that may also cause irreversible skin and eventually mucocutaneous lesions. This parasite can also infect dogs and represents a diagnostic challenge for veterinarians. Methods currently available for the diagnosis of ACL have a low sensitivity and may be time-consuming, representing a limit for treatment expedition of ACL. Quantitative real time PCR assays (qPCR) for the detection of L. (V.) braziliensis in canine blood samples were developed herein, and the detection limit and specificity of different molecular targets (kDNA and rDNA) evaluated. Of the protocols assessed, two qPCR assays, one targeting the kDNA and other the SSU rDNA of L. (V.) braziliensis, performed better, with detection limits of 100 fg and 10 pg, respectively. These assays were also used to test skin samples from humans with suspected ACL. The results indicate that the qPCR protocols developed represent an advance for the diagnosis of ACL in dogs and humans from this region, and provide a rapid and non-invasive diagnosis of the infection by L. (V.) braziliensis. Considering the quantitative nature of the assays, they will also be useful for monitoring treatment efficacy and preventing relapses in human patients in Brazil, although further studies are needed to critically evaluate the specificity of the qPCRs for their capacity to distinguish different Leishmania species and subspecies (represented by zymodemes) in other countries. Finally, molecular assays established may represent new tools for future basic and applied research focused on species identification, host–parasite associations, and infection dynamics in host and vector populations.  相似文献   
34.
35.
36.
Background Obesity is the most important risk factor for obstructive sleep apnea. It is estimated that 70% of sleep apnea patients are obese. In the morbidly obese, the prevalence may reach 80% in men and 50% in women. The aim of this study was to determine the prevalence and severity of sleep apnea in a group of morbidly obese patients, leading to bariatric surgery. Methods In a cross-sectional study developed in Bahia, northeastern Brazil. 108 patients (78 women and 30 men) from the Obesity Treatment and Surgery Center - “Núcleo de Tratamento e Cirurgia da Obesidade” underwent standard polysomnography. Patients with an apnea-hypopnea index (AHI) ≥ 5 events/hour were considered apneic. Results Mean ± SD for age and BMI were 37.1 ± 10.2 years and 45.2 ± 5.4 kg/m2, respectively. The calculated AHI ranged widely from 2.5 to 128.9 events/hour. Sleep apnea was detected in 93.6% of the sample, wherein 35.2% had mild, 30.6% moderate and 27.8% severe apnea. Oxyhemoglobin desaturation was directly related to the AHI and was more severe in men. Conclusion There was a high frequency of sleep apnea in this group of morbidly obese patients, for whom it was very important to request polysomnography, thus enabling therapeutic management and prognostication.  相似文献   
37.
PURPOSE: Cortical tremor, a form of rhythmic cortical myoclonus (rhythmic CM), and epilepsy have been described in families with autosomal dominant inheritance. Linkage analyses revealed two putative loci on chromosome 2p and 8q. Clinical photosensitivity was not a prominent feature in such families. We describe a large Italian family with rhythmic CM, photosensitivity, and epilepsy. METHODS: Twenty-three individuals of a five-generation family were studied. Linkage analyses for the loci on chromosome 2p11.1 and 8q23.3 were performed. RESULTS: Of the 23 studied family members, 16 were affected. Rhythmic CM of childhood onset was present in all 16 individuals (onset ranging from 3 to 12 years), was associated with photic-induced myoclonic jerks in seven, and with epileptic seizures in six (onset ranging from 23 to 34 years). Five children of the V generation manifested also episodes of arousal with generalized tremor in early infancy ("tremulous arousals"). Jerk-locked back-averaging of rhythmic CM of six affected individuals, documented a premyoclonic EEG correlate. C-reflex at rest was present in two affected adults. Linkage analyses excluded mapping to the 2p11.1 and 8q23.3 loci. CONCLUSIONS: Clinical variability and severity of the phenotypes in this family are in line with those of previously described pedigrees with autosomal dominant cortical myoclonus and epilepsy. In this family, a progression of symptoms was found: rhythmic CM and tremulous arousals occurred in childhood, whereas visually induced manifestations and epileptic seizures occurred during adolescence-adulthood. Exclusion of linkage to the two known loci is consistent with genetic heterogeneity of such familial clustering of symptoms.  相似文献   
38.

Background

Radiochemotherapy is the standard treatment for patients with carcinoma of the anal canal. Therefore, a surgical specimen is not usually obtained. Inguinal lymph node metastases cannot be accurately predicted by either clinical examination or imaging techniques. In this study, we applied the sentinel node technique in patients with anal canal squamous-cell carcinoma to determine whether this provided more reliable staging of tumors.

Methods

From May 2007 to May 2009, we enrolled 11 patients (7 women) with a mean age 65 (range 39–80) years with squamous-cell carcinoma of the anal canal and clinically and radiologically negative groin lymph nodes. The patients were staged with endorectal ultrasound, computed tomographic scan, magnetic resonance imaging of the pelvis, and positron emission tomography. There were two T1, four T2, and five T3 tumors (International Union Against Cancer classification). Lymphoscintigraphy with peritumoral 99mTc colloid injection was performed 16 to 18 h before surgery. During the surgery, patent blue dye was injected peritumorally, and the sentinel inguinal node was identified by a handheld gamma probe and dye visualization.

Results

The sentinel lymph node was detected in all 11 patients by scintigraphy; in 9 cases, the lymph node was in the inguinal region. All of these patients underwent radioguided node biopsy, and a total of 12 lymph nodes were removed. The average diameter of the resected nodes was 8 (range 4–20) mm. No serious complications occurred. In three patients, metastases were identified in the lymph node.

Conclusions

Sentinel node biopsy is a more accurate method than clinical or radiological techniques to stage the disease of patients with anal carcinoma.  相似文献   
39.
Background ACTH-independent macronodular adrenal hyperplasia (AIMAH) is a rare cause of Cushing’s syndrome. Bilateral adrenalectomy is considered the treatment of choice, with subsequent lifetime steroid replacement, but unilateral adrenalectomy has been recently proposed to reduce the secreting tissue. This prospective study was designed to evaluate the long-term results of unilateral adrenalectomy in AIMAH concerning the main laboratory and clinical abnormalities and the patient’s quality of life. Methods Seven consecutive patients with confirmed AIMAH underwent unilateral adrenalectomy of the largest gland. ACTH and cortisol levels, arterial blood pressure (BP), glycometabolic parameters, and patient’s subjective perception of health-related quality of life (by the SF-36 questionnaire) were measured preoperatively and postoperatively. Results No surgery-related morbidity occurred. One patient with a large contralateral adrenal enlargement required a completion adrenalectomy after 7 months because of persistent hypercortisolism. At a median follow-up of 53 (range, 27–68) months, the remaining six patients were cured, because serum and urinary free cortisol levels significantly decreased and ACTH increased, thus regaining the normal range. Both systolic and diastolic BP levels significantly reduced: 50% of patients definitively became normotensive, and the remaining patients reduced the need for antihypertensive treatment; 40% of patients suffering from preoperative diabetes were cured, whereas 40% reduced the need for hypoglycemizing drug. SF-36 evaluation of the health-related quality of life confirmed a significant amelioration. Conclusions Unilateral adrenalectomy of the largest gland can be an effective and safe treatment for AIMAH in case of asymmetric involvement. It may achieve long-term remission of Cushing’s syndrome and improve BP values, glycemic control, and patient’s quality of life.  相似文献   
40.
Previously, we demonstrated in heart transplant patients that FOXP3, a gene required for the development and function of regulatory T cells, was highly expressed in the graft during an acute cellular rejection. In this study, we analyzed whether the FOXP3 gene expression in the peripheral blood also reflects anti-donor immune responses, and therefore may provide clues for non-invasive detection of non-responsiveness or acute rejection. We examined the FOXP3 expression patterns of peripheral blood mononuclear cells (PBMC; n=69) of 19 heart transplant patients during quiescence and rejection in comparison with those of endomyocardial biopsies (EMB; n=75) of 24 heart transplant patients. While the FOXP3 mRNA levels were abundantly expressed in rejecting EMB (ISHLT rejection grade>1R) compared with EMB without histological evidence of myocardial damage (ISHLT rejection grade 0R-1R; p=0.003), no association with rejection or non-responsiveness was found for the FOXP3 mRNA levels in the peripheral blood. Thus, in contrast to intragraft FOXP3 gene expression, the peripheral FOXP3 mRNA levels lack correlation with anti-donor immune responses in the graft, and, consequently, FOXP3 does not appear to be a potential candidate gene for non-invasive diagnosis of non-responsiveness or rejection.  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