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   15562篇
  免费   995篇
  国内免费   188篇
耳鼻咽喉   387篇
儿科学   200篇
妇产科学   292篇
基础医学   2699篇
口腔科学   294篇
临床医学   1207篇
内科学   3069篇
皮肤病学   441篇
神经病学   1181篇
特种医学   1044篇
外科学   2090篇
综合类   71篇
现状与发展   3篇
一般理论   10篇
预防医学   605篇
眼科学   430篇
药学   1256篇
中国医学   153篇
肿瘤学   1313篇
  2024年   24篇
  2023年   133篇
  2022年   371篇
  2021年   661篇
  2020年   271篇
  2019年   440篇
  2018年   524篇
  2017年   409篇
  2016年   611篇
  2015年   873篇
  2014年   954篇
  2013年   1044篇
  2012年   1583篇
  2011年   1422篇
  2010年   837篇
  2009年   707篇
  2008年   890篇
  2007年   907篇
  2006年   770篇
  2005年   624篇
  2004年   518篇
  2003年   467篇
  2002年   381篇
  2001年   293篇
  2000年   237篇
  1999年   174篇
  1998年   71篇
  1997年   55篇
  1996年   34篇
  1995年   36篇
  1994年   24篇
  1993年   30篇
  1992年   38篇
  1991年   39篇
  1990年   34篇
  1989年   36篇
  1988年   28篇
  1987年   32篇
  1986年   17篇
  1985年   15篇
  1984年   10篇
  1983年   10篇
  1981年   14篇
  1980年   7篇
  1979年   14篇
  1978年   10篇
  1977年   10篇
  1976年   10篇
  1975年   9篇
  1973年   6篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
OBJECTIVE: Evidence from previous studies suggests that heavy alcohol use (HAU) exacerbates the rate of fibrosis progression in the liver and results in increased probability for premature death among patients with hepatitis C virus (HCV) infection. The current study uses population-based mortality data to investigate whether heavy drinking affects the age of death among individuals with HCV and, if so, whether this effect differs between men and women. METHODS: A total of 7,263,163 death records in the United States between 2000 and 2002 were drawn from the Multiple Cause of Death (MCD) public-use data files compiled by the National Center for Health Statistics (NCHS). International Classification of Diseases, Tenth Revision (ICD-10) codes were used to identify the presence of HCV (B17.1 and B18.2) and HAU (as indicated by alcohol-induced medical conditions, F10 and K70) either as the underlying cause or as one of the contributing causes of death. The deaths were divided into 4 distinctive cause-of-death categories: HCV without HAU, HAU without HCV, HCV plus HAU, and all others. The mean ages of death and the cumulative probabilities of death derived from multiple-cause life table were compared across these categories. RESULTS: Hepatitis C virus deaths showed an excessive prevalence of HAU when compared with non-HCV deaths. Compared with deaths of HCV without HAU, the mean age of death was shortened for deaths of HCV plus HAU (from 55.1 to 50.0 years among males, and from 61.0 to 49.1 years among females). The cumulative probability of death before age 65 was much higher for the latter than the former group (0.91 vs 0.68 among males, and 0.88 vs 0.47 among females). While HCV alone showed a disproportionate effect on premature death in males, HAU presented a stronger effect in females, resulting in a "catching-up" effect that diminished the gender difference in age of HCV death. CONCLUSIONS: This study provides mortality-based evidence to further establish heavy alcohol consumption as one of the key risk factors contributing to premature deaths from HCV in the United States. More importantly, this study, for the first time, presents empirical evidence that alcohol consumption affects men and women differently in HCV mortality.  相似文献   
62.
Peroxisome proliferator-activated receptor-γ (PPARγ) agonists exhibit potent anti-fibrotic effects in the lung and other tissues. Recently, micro-computed tomography (CT) has been a useful tool for the investigation of lung diseases in small animals and is now increasingly applied to visualize and quantify the pulmonary structures. However, there is little information on the assessment for therapeutic effects of PPARγ agonists on the pulmonary fibrosis in mice using micro-CT. This study was aimed to determine the capability of micro-CT in examining the effects of rosiglitazone on pulmonary fibrosis. We used a murine model of bleomycin-induced lung fibrosis to evaluate the feasibility of micro-CT in evaluating the therapeutic potential of rosiglitazone on pulmonary fibrosis, comparing with pathologic scores. On micro-CT findings, ground glass opacity (80%) and consolidation (20%) were observed predominantly at 3 weeks after the instillation of bleomycin, and the radiologic features became more complex at 6 weeks. In bleomycin-instilled mice treated with rosiglitazone, the majority (80%) showed normal lung features on micro-CT. Radiological-pathologic correlation analyses revealed that ground glass opacity and consolidation were correlated closely with acute inflammation, while reticular opacity was well correlated with histological honeycomb appearance. These results demonstrate that rosiglitazone displays a protective effect on pulmonary fibrosis in mice and that the visualization of bleomycin-induced pulmonary fibrosis using micro-CT is satisfactory to assess the effects of rosiglitazone. It implies that micro-CT can be applied to evaluate therapeutic efficacies of a variety of candidate drugs for lung diseases.  相似文献   
63.
Adenoid cystic carcinoma of Bartholin glands (BG-ACC) is a rare, slow-growing but a highly aggressive tumor with remarkable capacity for local recurrence and distant metastasis. The purpose of this study was to elucidate our experiences of the diagnosis and treatment of BG-ACC and to analyze the clinical outcomes and prognosis of patients with BG-ACC. A retrospective chart review was performed to assess the demographic information, chief complaints, pathologic features of tumors, primary treatment, and development of local recurrence or distant metastasis, as well as the patient outcome. All patients received surgical excision as the primary treatment, and the diagnosis of BG-ACC was confirmed histopathologically. Three of four patients whose tumors showed pathologic features indicating a high probability of recurrence received adjuvant radiotherapy. These patients did not develop local recurrence, in contrast, one patient who did not receive adjuvant radiotherapy developed local recurrence and distant metastasis on several occasions. All patients who received primary surgical treatment are alive to date. When patients who are more than 40 years of age and who present with symptomatic BG lesions, BG-ACC should be included in the differential diagnosis and biopsy should be performed for histopathologic confirmation. Radical local excision with sufficient negative margins seems to be beneficial for primary treatment. Adjuvant radiotherapy is a reasonable treatment option for patients with high risk factors after surgery or for patients who develop local recurrence.  相似文献   
64.
Drug-resistant tuberculosis (TB) has lent urgency to finding new drug leads with novel modes of action. A high-throughput screening campaign of >65,000 actinomycete extracts for inhibition of Mycobacterium tuberculosis viability identified ecumicin, a macrocyclic tridecapeptide that exerts potent, selective bactericidal activity against M. tuberculosis in vitro, including nonreplicating cells. Ecumicin retains activity against isolated multiple-drug-resistant (MDR) and extensively drug-resistant (XDR) strains of M. tuberculosis. The subcutaneous administration to mice of ecumicin in a micellar formulation at 20 mg/kg body weight resulted in plasma and lung exposures exceeding the MIC. Complete inhibition of M. tuberculosis growth in the lungs of mice was achieved following 12 doses at 20 or 32 mg/kg. Genome mining of lab-generated, spontaneous ecumicin-resistant M. tuberculosis strains identified the ClpC1 ATPase complex as the putative target, and this was confirmed by a drug affinity response test. ClpC1 functions in protein breakdown with the ClpP1P2 protease complex. Ecumicin markedly enhanced the ATPase activity of wild-type (WT) ClpC1 but prevented activation of proteolysis by ClpC1. Less stimulation was observed with ClpC1 from ecumicin-resistant mutants. Thus, ClpC1 is a valid drug target against M. tuberculosis, and ecumicin may serve as a lead compound for anti-TB drug development.  相似文献   
65.
ObjectiveTo assess the performance of diffusion tensor imaging (DTI) for the diagnosis of cervical spondylotic myelopathy (CSM) in patients with deformed spinal cord but otherwise unremarkable conventional magnetic resonance imaging (MRI) findings.ResultsThe MD, LD, and RD cut-off values were 1.079 × 10-3, 1.719 × 10-3, and 0.749 × 10-3 mm2/sec, respectively, and that of FA was 0.475. Sensitivity, specificity, positive predictive value and negative predictive value were: 100 (4/4), 44.8 (13/29), 20 (4/20), and 100 (13/13) for MD; 100 (4/4), 27.6 (8/29), 16 (4/25), and 100 (8/8) for FA; 100 (4/4), 58.6 (17/29), 25 (4/16), and 100 (17/17) for MD∩FA; 100 (4/4), 68.9 (20/29), 30.8 (4/13), and 100 (20/20) for LD∩FA; and 75 (3/4), 68.9 (20/29), 25 (3/12), and 95.2 (20/21) for RD∩FA in percentage value. Diagnostic performance comparisons revealed significant differences only in specificity between FA and MD∩FA (p = 0.003), FA and LD∩FA (p < 0.001), FA and RD∩FA (p < 0.001), MD and LD∩FA (p = 0.024) and MD and RD∩FA (p = 0.024).ConclusionFractional anisotropy combined with MD, RD, or LD is expected to be more useful than FA and MD for diagnosing CSM in patients who show deformed spinal cords without signal changes on MRI.  相似文献   
66.
ObjectiveTo evaluate the correlation between bone tunnel diameter after anterior cruciate ligament (ACL) reconstruction measured by computed tomography (CT) using multiplanar reconstruction (MPR) and stability or clinical scores.ResultsThe tibial bone tunnels for the anteromedial bundles were significantly widened at T2 compared with T1 (observer 1, 0.578 mm to 0.698 mm, p value of < 0.001; observer 2, 0.581 mm to 0.707 mm, p value of < 0.001). There was no significant correlation between the diameter at T2 and stability or clinical scores and between the interval change ratio ([T2 - T1] / T1) and stability or clinical scores (corrected p values for all were 1.0). Intraobserver agreement for measurements was excellent (> 0.8) for both observers. Interobserver agreement for measurement was excellent (> 0.8) except for the most distal portion of the femoral bone tunnel for anterior medial bundle in immediate postoperative CT, which showed moderate agreement (concordance correlation coefficient = 0.6311).ConclusionNeither the diameter nor its change ratio during interval follow-up is correlated with stability or clinical scores.  相似文献   
67.
As a high quantity of melanin can lead to hyperpig­mentation or skin cancer in humans and it can also activate lysosomal enzymes so in the present study the changes in lysosomal enzymes upon exposure of HeLa cells to melanin has been studied. The HeLa cells were exposed to 100 ppm melanin for 24 hours and lysosomal enzymes were extracted. The lysosomal enzymes were identified through two­dimensional polyacrylamide gel electrophoresis (2­DE) after exposure of HeLa cells to melanin. The results showed 12 up­ and 3­down regulation spots in relation to melanin exposure. It has been observed that lysosomal proteins are related to melanin to decrease the color and quantity through cellular activation of lysosomes.  相似文献   
68.
69.
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