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   11674篇
  免费   660篇
  国内免费   39篇
耳鼻咽喉   147篇
儿科学   303篇
妇产科学   267篇
基础医学   1496篇
口腔科学   349篇
临床医学   1051篇
内科学   2123篇
皮肤病学   92篇
神经病学   1399篇
特种医学   268篇
外科学   1321篇
综合类   149篇
一般理论   27篇
预防医学   1191篇
眼科学   331篇
药学   920篇
中国医学   28篇
肿瘤学   911篇
  2022年   47篇
  2021年   134篇
  2020年   77篇
  2019年   153篇
  2018年   204篇
  2017年   150篇
  2016年   165篇
  2015年   180篇
  2014年   289篇
  2013年   487篇
  2012年   678篇
  2011年   746篇
  2010年   410篇
  2009年   399篇
  2008年   788篇
  2007年   837篇
  2006年   803篇
  2005年   876篇
  2004年   847篇
  2003年   851篇
  2002年   832篇
  2001年   96篇
  2000年   56篇
  1999年   101篇
  1998年   153篇
  1997年   144篇
  1996年   133篇
  1995年   109篇
  1994年   94篇
  1993年   111篇
  1992年   83篇
  1991年   69篇
  1990年   62篇
  1989年   62篇
  1988年   60篇
  1987年   45篇
  1986年   56篇
  1985年   69篇
  1984年   120篇
  1983年   81篇
  1982年   110篇
  1981年   122篇
  1980年   90篇
  1979年   56篇
  1978年   54篇
  1977年   46篇
  1976年   39篇
  1975年   38篇
  1974年   39篇
  1973年   28篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Cripe  Larry D. 《JAMA》2007,298(16):1841
  相似文献   
12.
Book reviewed in this article: The Needs of Strangers . By Michael Ignatieff. The Health Economy . By Victor Fuchs. Just Health Care . By Norman Daniels  相似文献   
13.
14.
Impact of smoking on cancer stage at diagnosis.   总被引:2,自引:0,他引:2  
BACKGROUND: Studies evaluating the relationship between smoking and cancer spread are limited. METHODS: We studied the relationship between cancer stage at diagnosis (local, regional, or metastatic) and smoking history (current, previous, or nonsmoker). For lung cancer, patterns of spread were also studied. RESULTS: In a tumor registry for eastern North Dakota, northwestern Minnesota, and northern South Dakota, 11,716 cases were identified from 1986 to 2001. Current smokers (relative risk [RR], 2.11; 95% confidence interval, 1.93 to 2.32; P <.001) and previous smokers (RR, 1.56; 95% confidence interval, 1.42 to 1.72; P <.001) had an increased risk of metastatic disease at diagnosis. Current smokers (RR, 1.39; 95% confidence interval, 1.29 to 1.51; P <.001), but not previous smokers, also had an increased risk of regional disease. An increase in metastatic disease was most evident for prostate cancer (RR, 1.53; P =.003). An increase in regional disease was most evident for head and neck (RR, 3.53; P <.001), prostate (RR, 1.83; P =.030), and breast cancer (RR, 1.22; P =.005). Compared with previous smokers, current smokers with metastatic lung cancer were more likely to have involvement of the brain (33.6% v 23.0%; P =.004), bone marrow, adrenal gland, and pericardium (24.7% v 15.9%; P =.004). CONCLUSION: Previous or current smoking is a risk factor for increased cancer stage in a wide range of malignancies. Further study is required to determine whether this association is causal.  相似文献   
15.
Complications of laparoscopy are categorized into trocar insertion complications, complications resulting from image quality, and complications resulting from instrumentation. Microlaparoscopy also has similar complications and additional complications when being performed in the awake patient. Each of these complications is reviewed as they apply to microlaparoscopy. The results reveal that the seriousness of the complication is directly dependent on the size of the perforation. Therefore, surgeons' reluctance to downsize the instruments used is increasing the laparoscopy complication rate. Using smaller-diameter trocars and instruments reduces laparoscopic complication rates.  相似文献   
16.
Summary An infant with persistent truncus arteriosus associated with splenic agenesis and the asplenia syndrome is reported, including clinical, echocardiographic and autopsy findings. To the authors' knowledge this association has not been previously reported.  相似文献   
17.
Reports suggest that response tointerferon-alpha therapy is influenced by both hepatitisC viral genotype and titer. Our aim was to determine ifdirect, automated, cycle sequencing of the PCR productfrom an HCV RNA detection assay could be used toreliably determine HCV genotype. In addition, theapproach was used to determine the HCV genotypedistribution in our patient population and to learn ifthere was a correlation between HCV genotype and RNAtiter that could be used to predict response totreatment. In all 143 consecutive patients were testedfor both HCV RNA titer and genotype. Automated, cycle sequencing of PCR product was highly effectiveand failed to yield a genotype in only 3 (2%) patients.The distribution of HCV genotypes was: 1a (40%), 1b(39%), 2a (2%), 2b (6%), 3a (4%). There were significant differences in the median HCV RNA titersbetween genotypes 1, 2, and 3. 6 High HCV RNA titers>4.4 × 106 copies/ml were only seenin genotype 1. However, the HCV RNA level should not beused as a surrogate marker of genotype because of a significantoverlap of titers within the genotypes.  相似文献   
18.
The syndrome of senile gait   总被引:1,自引:0,他引:1  
Summary Infrared computed stroboscopic photometry was used to quantify the kinematic profiles of walking in 10 elderly patients with symmetrical neurological disturbances of gait and in 19 age-matched neurologically healthy people. Clinical examination of the patients revealed similar profiles of walking even though their diagnoses were vascular dementia (2), normal pressure hydrocephalus (2), Alzheimer dementia with possible normal pressure hydrocephalus (2), mixed Alzheimer and vascular dementia (1), peripheral neuropathy (1), Alzheimer dementia with parkinsonian features (1), and un determined (1). Quantitatively, the patients' gait kinematics deviated greatly from control values, but these deviations were statistically attributable to reductions in stride. We suggest that many gait disturbances in elderly people are similar, regardless of etiology, because the characteristics of these gait disturbances are heavily veiled by nonspecific stride-dependent changes that comprise the syndrome of senile gait.  相似文献   
19.
Summary: In animals and in humans, T-cell therapy can cure advanced disseminated leukemia that would otherwise be fatal. The therapeutic effect of immune T cells is quantitative. As the dose of effector T cells is increased, survival is proportionately increased. Therefore, effective T-cell therapy is predicated on the ability to procure large numbers of immune effector T cells. By using cultured T cells, the number of immune T cells can be increased in vivo substantially above che level achievable by vaccination. The survival of cultured T ceils in vivo is dependent upon both the culture conditions used and the therapeutic regimens employed. Under appropriate conditions, cultured T ceils can proliferate in vivo in response to stimulation by antigen, distribute widely and survive long term to provide effector function and immunologic memory. Given that T cells recognize peptides. the need for immunization with tumor can be circumvented by immunization with peptide. Peptide-specific T cells and the progeny of single T-cell clones can provide the necessary cellular functions to eradicate disseminated murine leukemia. The ability of cloned T cells to similarly provide substantial measurable immunity in humans has been validated in clinical trials. By priming with peptides and by using established culture conditions, T-cell therapy can now be directed against virtually any antigen within the host T-cell repertoire. The major remaining question to be answered is which proteins and which peptides are the most suitable targets for T-cell therapy trials.  相似文献   
20.
For 3 months in 1969 a family in the United States that included a pregnant mother consumed pork containing methylmercury. Children, aged 20, 13, and 8 years and a neonate, developed severe neurological signs. Twenty-two years later, the 2 oldest had cortical blindness or constricted visual fields, diminished hand proprioception, choreoathetosis, and atentional deficits. Magnetic resonance images showed tissue loss in the calcarine and parietal cortices and cerebellar folia. The youngest had quadriplegia, blindness, and severe mental retradation until their deaths. The brain of the 8-year-old who died at age 30 showed cortical atrophy, neuronal loss, and gliosis, most pronounced in the paracentral and parietooccipital regions. The total mercury level in formalin-fixed, left occipital cortex was 1,974 ng/gm as measured by atomic absorption. Regional brain mercury levels correlated with extent of brain damage. A control patient had 38.5 ng of mercury/gm in the occipital cortex. Systemic organs in the patient and a control subject had comparable mercury levels. In mercury-intoxicated rats, we found that only 5 to 10% of total brain mercury was lost by formalin fixation. Brain inorganic mercury in the patient ranged from 82 to 100%. Since inorganic mercury crosses the blood-brain barrier poorly, biotransformation of methyl to inorganic mercury may have occurred after methylmercury crossed the blood-brain barrier, accounting for its persistence in brain and causing part of the brain damage.  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