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   9394篇
  免费   707篇
  国内免费   10篇
耳鼻咽喉   158篇
儿科学   373篇
妇产科学   370篇
基础医学   1329篇
口腔科学   455篇
临床医学   946篇
内科学   1494篇
皮肤病学   273篇
神经病学   874篇
特种医学   299篇
外科学   1437篇
综合类   141篇
一般理论   3篇
预防医学   754篇
眼科学   214篇
药学   524篇
中国医学   13篇
肿瘤学   454篇
  2021年   144篇
  2020年   76篇
  2019年   136篇
  2018年   151篇
  2017年   106篇
  2016年   138篇
  2015年   138篇
  2014年   204篇
  2013年   269篇
  2012年   361篇
  2011年   428篇
  2010年   228篇
  2009年   235篇
  2008年   348篇
  2007年   404篇
  2006年   433篇
  2005年   373篇
  2004年   358篇
  2003年   283篇
  2002年   291篇
  2001年   310篇
  2000年   285篇
  1999年   256篇
  1998年   97篇
  1997年   92篇
  1996年   79篇
  1995年   90篇
  1994年   78篇
  1993年   83篇
  1992年   209篇
  1991年   174篇
  1990年   216篇
  1989年   203篇
  1988年   206篇
  1987年   192篇
  1986年   178篇
  1985年   167篇
  1984年   138篇
  1983年   118篇
  1979年   118篇
  1978年   89篇
  1977年   79篇
  1975年   88篇
  1974年   91篇
  1973年   90篇
  1972年   78篇
  1971年   86篇
  1970年   83篇
  1969年   77篇
  1968年   76篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
Idiopathic perioptic neuritis is a term used to describe noninfectious inflammatory disorders of the optic nerve sheaths, the causes of which are unknown. In the following report, a 68-year-old woman with bilateral visual loss was found to have chronic inflammation with necrobiotic granulomas of her optic nerve sheaths. The patient, who had no systemic condition known to be associated with necrobiotic granuloma, lost vision from infarction of the optic nerve parenchyma and from compression due to thickened meninges. Although there are similarities between the inflammatory reaction in this case to the necrobiotic dermatoses, the pathogenesis of this condition remains obscure.  相似文献   
22.
PURPOSE: This study was designed to identify risk indicators for the prevalence at enrollment and incidence over 36 months of periodontal pathology and coronal caries experience affecting third molars in a community-based study of people over 65 years of age. SUBJECTS AND METHODS: Data from a subsample of 810 dentate subjects from the Piedmont 65+ Study were available for analyses. All visible teeth were examined. Periodontal probing measures were taken at 2 sites, mesiobuccal and buccal/facial. Clinical data on caries experience were collected by visual-tactile examination. At enrollment, 340 subjects had at least 1 visible third molar; all were examined for caries experience. Periodontal probing measures were available for 277 of these same subjects. The significance of the possible risk indicators for periodontal pathology and caries affecting third molars was determined by chi(2) tests. Statistical significance was set at .05. Logistic multivariable models were used to derive odds ratios and 95% confidence intervals. RESULTS: African-American subjects were more likely to have visible third molars (P < .01). Caucasian subjects were more likely to have third molar coronal caries experience (P < .01), as were subjects with greater than a high school education and those with a dental visit within 3 years (both P < .01). However, African American subjects were more likely to have periodontal pathology, CALs >/= 3 mm on third molars (P < .01), as were those who used tobacco (P < .01). None of the other risk indicators we studied were associated with progression of periodontal pathology or coronal caries experience on visible third molars. CONCLUSION: In this population study of senior adults, Caucasians and African Americans appear to have different levels of risk for caries experience and periodontal pathology affecting retained third molars.  相似文献   
23.
24.
25.
Surgical glove powders bind latex antigens.   总被引:4,自引:0,他引:4  
Latex surgical gloves have recently been identified as a potential source of allergens. Much of the current information suggests that the soluble proteins in latex may cause significant reactions in sensitive individuals. The starch powders used as a lubricant on some latex gloves have also been identified as potential allergens in some patients. In this study, we determined these powders to act as potential carriers of latex allergens. We have produced a polyclonal antiserum to be used as a reagent to study latex proteins. By Western blot analysis, we identified a significant interaction between latex proteins and starch powders. The binding of latex proteins to starch particles results in a glove particle that may have an increased potential to act as an allergen. The latex protein-starch particles represent a potential mechanism for exposure and sensitization of health care workers to latex allergens. Elimination of these particles from the operating room should reduce the route of sensitization and the potential for adverse reactions to latex.  相似文献   
26.
In the presence of spiperone to block the 5-HT1A-mediated inhibition of pyramidal cell activity, 5-hydroxytryptamine (serotonin, 5-HT) produces a rapid transient increase in amplitude of the extracellularly recorded population spike from area CA1 of the hippocampus. Intracellular recording techniques in area CA1 of rat hippocampal slices were used to identify the ionic mechanism and to characterize the 5-HT receptor mediating this excitatory response to 5-HT. Most of the experiments were conducted in the presence of spiperone to block the 5HT1A hyperpolarization. Since spiperone also has high affinity for 5-HT2 receptors, any response mediated by 5-HT2 receptors would also be blocked. Bath perfusion of the slice with 5-HT increased the rectification of pyramidal cells in the subthreshold region, increased the resistance, and increased the amplitude of subthreshold excitatory postsynaptic potentials (EPSPs) to initiate spike firing. The 5-HT2,1C-selective agonist DOI mimicked this effect of 5-HT, and the 5-HT2,1C antagonist ketanserin (1 microM) blocked the effect of DOI. There was no change in the amplitude of the slow afterhyperpolarization (sAHP) or the amplitude of evoked inhibitory postsynaptic potentials (IPSPs). The increase in rectification and EPSP amplitude by 5-HT occurred even in the presence of the 5-HT4-selective antagonist BRL 24924 to prevent the decrease in amplitude of the sAHP by 5-HT. We conclude that 5-HT produces a fast excitatory response by increasing subthreshold conductance in CA1 hippocampal pyramidal cells. The identity of the receptor mediating this response was not conclusively identified, but resembled the 5-HT1C receptor.  相似文献   
27.
The peripheral vascular response to Escherichia coli endotoxin (1 mg/kg/i.v.) was measured for 2 hr in the pentobarbital anesthetized dog. Total venous return was collected and returned by a pump to the right atrium to maintain a constant cardiac output. Occlusion of the venous lines permitted estimation of venous compliance in the systems drained by the superior (SVC) and inferior vena cavae (IVC). After endotoxin administration, arterial pressure and total peripheral resistance rapidly dropped and remained low for 2 hr. IVC compliance was decreased at 10-30 min and SVC compliance at 10 min after endotoxin. The decrease in compliance is interpreted as venous dilation and probably venous pooling. The latter may account for a substantial portion of the total venous pooling reported in early endotoxin shock. After 30 min, compliance increased and by 60 min was equal to control. Left ventricular relaxation ability decreased as indicated by maximal negative dp/dt. Ibuprofen, 10 mg/kg, was administered at 120 min or earlier, depending on the state of the animal; rapid recovery of arterial pressure and ventricular function occurred without a significant change in venous compliance.  相似文献   
28.
J R Dura  S J Beck 《Pain》1988,35(1):79-89
Multiple aspects of family functioning were assessed when mothers experienced either chronic pain, a chronic illness (diabetes), or no illness. Mothers' and fathers' self-report measures of depression, anxiety, and family environment were collected. Children's self-report measures of depression and anxiety, as well as information about their overall adjustment, were collected. Family communication patterns were also assessed. Families with a mother who had chronic pain had poorer perceived family environments and higher levels of depression and anxiety compared to the other two groups of families. Children from chronic pain families also appeared to be adversely affected. The data suggest that level of disability appeared more salient than the type of chronic illness. Implications of the findings are discussed in light of the fact that mothers with chronic pain in the present sample reported relatively mild disability and were not actively seeking treatment for their condition.  相似文献   
29.
30.
The frequency of heterozygous protein C and protein S deficiency, detected by measuring total plasma antigen, in a group (n = 141) of young unrelated patients (less than 45 years old) with venous thrombotic disease was studied and compared to that of antithrombin III, fibrinogen, and plasminogen deficiencies. Among 91 patients not receiving oral anticoagulants, six had low protein S antigen levels and one had a low protein C antigen level. Among 50 patients receiving oral anticoagulant therapy, abnormally low ratios of protein S or C to other vitamin K-dependent factors were presented by one patient for protein S and five for protein C. Thus, heterozygous Type I protein S deficiency appeared in seven of 141 patients (5%) and heterozygous Type I protein C deficiency in six of 141 patients (4%). Eleven of thirteen deficient patients had recurrent venous thrombosis. In this group of 141 patients, 1% had an identifiable fibrinogen abnormality, 2% a plasminogen abnormality, and 3% an antithrombin III deficiency. Thus, among the known plasma protein deficiencies associated with venous thrombosis, protein S and protein C deficiencies (9%) emerge as the leading identifiable associated abnormalities.  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