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   5028篇
  免费   318篇
  国内免费   37篇
耳鼻咽喉   81篇
儿科学   129篇
妇产科学   127篇
基础医学   778篇
口腔科学   101篇
临床医学   697篇
内科学   873篇
皮肤病学   94篇
神经病学   661篇
特种医学   170篇
外科学   467篇
综合类   33篇
一般理论   4篇
预防医学   384篇
眼科学   102篇
药学   280篇
中国医学   5篇
肿瘤学   397篇
  2024年   7篇
  2023年   44篇
  2022年   77篇
  2021年   174篇
  2020年   98篇
  2019年   135篇
  2018年   160篇
  2017年   120篇
  2016年   144篇
  2015年   166篇
  2014年   216篇
  2013年   247篇
  2012年   373篇
  2011年   371篇
  2010年   261篇
  2009年   205篇
  2008年   308篇
  2007年   341篇
  2006年   288篇
  2005年   272篇
  2004年   273篇
  2003年   210篇
  2002年   258篇
  2001年   45篇
  2000年   45篇
  1999年   57篇
  1998年   43篇
  1997年   41篇
  1996年   34篇
  1995年   33篇
  1994年   33篇
  1993年   21篇
  1992年   21篇
  1991年   23篇
  1990年   21篇
  1989年   13篇
  1988年   14篇
  1987年   15篇
  1986年   15篇
  1983年   8篇
  1982年   8篇
  1981年   7篇
  1980年   7篇
  1979年   10篇
  1977年   13篇
  1976年   16篇
  1975年   8篇
  1973年   13篇
  1972年   10篇
  1966年   7篇
排序方式: 共有5383条查询结果,搜索用时 0 毫秒
1.
2.
结果 髌股关节的压力与应力随膝关节屈曲角度的增加而升高,随膝关节屈曲角度的减小而降低(图3~8).不同膝关节屈曲角度下弓步变化和跨步变化的髌股关节压力见表1.  相似文献   
3.
4.
Evidence that genetic disposition for adult lactose intolerance significantly affects calcium intake, bone density, and fractures in postmenopausal women is presented. PCR-based genotyping of lactase gene polymorphisms may complement diagnostic procedures to identify persons at risk for both lactose malabsorption and osteoporosis. INTRODUCTION: Lactase deficiency is a common autosomal recessive condition resulting in decreased intestinal lactose degradation. A -13910 T/C dimorphism (LCT) near the lactase phlorizin hydrolase gene, reported to be strongly associated with adult lactase nonpersistence, may have an impact on calcium supply, bone density, and osteoporotic fractures in the elderly. MATERIALS AND METHODS: We determined LCT genotypes TT, TC, and CC in 258 postmenopausal women using a polymerase chain reaction-based assay. Genotypes were related to milk intolerance, nutritional calcium intake, intestinal calcium absorption, bone mineral density (BMD), and nonvertebral fractures. RESULTS: Twenty-four percent of all women were found to have CC genotypes and genetic lactase deficiency. Age-adjusted BMD at the hip in CC genotypes and at the spine in CC and TC genotypes was reduced by -7% to -11% depending on the site measured (p = 0.04). LCT(T/C-13910) polymorphisms alone accounted for 2-4% of BMD in a multiple regression model. Bone fracture incidence was significantly associated with CC genotypes (p = 0.001). Milk calcium intake was significantly lower (-55%, p = 0.004) and aversion to milk consumption was significantly higher (+166%, p = 0.01) in women with the CC genotype, but there were no differences in overall dietary calcium intake or in intestinal calcium absorption test values. CONCLUSION: The LCT(T/C-13910) polymorphism is associated with subjective milk intolerance, reduced milk calcium intake, and reduced BMD at the hip and the lumbar spine and may predispose to bone fractures. Genetic testing for lactase deficiency may complement indirect methods in the detection of individuals at risk for both lactose malabsorption and osteoporosis.  相似文献   
5.
6.
Abstract. Registered nurses regarded as “experienced and good” in dementia care were interviewed about the feeding of a severely demented patient who showed refusal-like feeding behaviour. Not one of the twenty nurses could see herself using force against her patients. Most interviewees justified their decisions to feed a severely demented patient and answered questions about whether they would change their minds if there were certain circumstances in terms of words that could be interpreted as referring to the ethical principle of beneficence. The nurses stressed the difficulty to understand the meaning of severely demented patients' feeding behaviour and decide when force-feeding occurs. When asked to rank ethical principles of importance for the decision, however, the most common answer was that they would give priority to the ethical principle of autonomy. The nurses did not see the ethical principles as separate entities, that could be applied one by one, but tried to integrate them into a whole. The findings of this study were interpreted as indicating that principled ethics is not an adequate model to describe experienced nurses' ethical reasoning.  相似文献   
7.

Introduction  

Cattle are an important source of allergens in the working area of farmers. Asthma caused by cow allergens is a significant occupational problem. Yet in allergological testing, the results of in vivo and in vitro diagnostic tests are often inconsistent even in cases with clearly cattle-related symptoms.  相似文献   
8.
Background Current influenza pandemic models predict a surge in influenza‐related hospitalizations in affected jurisdictions. One proposed strategy to increase hospital surge capacity is to restrict elective hospitalizations, yet the degree to which this measure would meet the anticipated is unknown. Objectives To compare the reduction in hospitalizations resulting from widespread nonurgent hospital admission restrictions during the Toronto severe acute respiratory syndrome (SARS) outbreak with the expected increase in admissions resulting from an influenza pandemic in Toronto. Methods The authors compared the expected influenza‐related hospitalizations in the first eight weeks of a mild, moderate, or severe pandemic with the actual reduction in the number of hospital admissions in Toronto, Ontario, during the first eight weeks of the SARS‐related restrictions. Results Influenza modeling for Toronto predicts that there will be 4,819, 8,032, or 11,245 influenza‐related admissions in the first eight weeks of a mild, moderate, or severe pandemic, respectively. In the first eight weeks of SARS‐related hospital admission restrictions, there were 3,654 fewer hospitalizations than expected in Toronto, representing a modest 12% decrease in the overall admission rate (a reduction of 1.40 admissions per 1,000 population). Therefore, influenza‐related admissions could exceed the reduction in admissions resulting from restricted hospital utilization by 1,165 to 7,591 patient admissions, depending on pandemic severity, which corresponds to an excess of 0.44 to 2.91 influenza‐related admissions per 1,000 population per eight weeks, and an increase of 4% to 25% in the overall number of admissions, when compared with nonpandemic conditions. Conclusions Pandemic modeling for Toronto suggests that influenza‐related admissions would exceed the reduction in hospitalizations seen during SARS‐related nonurgent hospital admission restrictions, even in a mild pandemic. Sufficient surge capacity in a pandemic will likely require the implementation of other measures, including possibly stricter implementation of hospital utilization restrictions.  相似文献   
9.
Receptor-targeted scintigraphy and radionuclide therapy with radiolabeled somatostatin analogs are successfully applied for somatostatin receptor-positive tumors. The synergistic effects of an apoptosis-inducing factor, for example, the Arg-Gly-Asp (RGD) motif, can increase the radiotherapeutic efficacy of these peptides. Hence, the tumoricidal effects of the hybrid peptide RGD-diethylaminetriaminepentaacetic acid (DTPA)-Tyr3-octreotate (cyclic[c](Arg-Gly-Asp-D-Tyr-Asp)-Lys(DTPA)-D-Phe-c(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr), hereafter referred to as RGD-DTPA-octreotate, were evaluated in comparison with those of RGD (c(Arg-Gly-Asp-D-Tyr-Asp)) and Tyr3-octreotate (D-Phe-c(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr). METHODS: The therapeutic effects of RGD-111In-DTPA-octreotate, 111In-DTPA-RGD, and 111In-DTPA-Tyr3-octreotate were investigated with various cell lines by use of a colony-forming assay, and caspase-3 activity was also determined. RESULTS: Tumoricidal effects were found with 111In-DTPA-RGD, 111In-DTPA-Tyr3-octreotate, and RGD-111In-DTPA-octreotate, in order from least effective to most effective. Also, the largest increase in caspase-3 levels was found with RGD-111In-DTPA-octreotate. CONCLUSION: RGD-111In-DTPA-octreotate has more pronounced tumoricidal effects than 111In-DTPA-RGD and 111In-DTPA-Tyr3-octreotate, because of increased apoptosis, as indicated by increased caspase-3 activity.  相似文献   
10.
Two patients with bilateral extensive confluent choroidal lesions, exudative retinal detachments, positive lyme serology and a typical history are documented: A 32-year-old woman presented 14 days after a "flu-like" illness with bilateral acute extensive choroidal lesions and exudative retinal detachments (OD from 5 to 8:30 o'clock, OS from 5 to 8 o'clock, both including the macula) accompanied by a mild lymphocytic meningitis. The laboratory work-up revealed increased serum and CSF titers of antibodies against Borrelia burgdorferi (Lyme immunofluorescent test (IFT) and Lyme-IgM IFT) which declined after a 14-day treatment with doxycycline (200 mg/d), CSF titers non-detectable (serum IgG: from 1:640 to 1:320, serum IgM: from 1:40 to 1:20). A distinct improvement with visual acuity increasing from OD 0.2/OS 0.3 p to OD/OS 0.8 p was observed after seven days of treatment. A 40-year-old man with a 14-day history of tick-bite developed the same, though more severe ocular findings and a lymphocytic meningitis. The serological work-up revealed increased antibody titers against Borrelia burgdorferi (ELISA); the IgM titer was normal. After a 10-day treatment with penicillin, antibody titers against the spirochete decreased slightly and the patient's neurologic and ophthalmologic status improved dramatically. Five weeks after admission visual acuity was OD/OS 0.5 (compared to OD/OS 0.1) and has remained at 0.8 p (OD/OS) since the ninth week after onset. The clinical course of the disease and the decreasing lyme serology strongly suggest an infection with Borrelia burgdorferi. The authors propose thorough laboratory work-ups including tests for Lyme disease in selected patients with diffuse choroidal lesions.  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