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   9525篇
  免费   736篇
  国内免费   21篇
耳鼻咽喉   159篇
儿科学   374篇
妇产科学   376篇
基础医学   1339篇
口腔科学   460篇
临床医学   959篇
内科学   1547篇
皮肤病学   274篇
神经病学   875篇
特种医学   345篇
外科学   1445篇
综合类   145篇
一般理论   3篇
预防医学   758篇
眼科学   215篇
药学   532篇
中国医学   14篇
肿瘤学   462篇
  2021年   144篇
  2020年   78篇
  2019年   136篇
  2018年   153篇
  2017年   109篇
  2016年   142篇
  2015年   143篇
  2014年   208篇
  2013年   272篇
  2012年   364篇
  2011年   430篇
  2010年   232篇
  2009年   240篇
  2008年   350篇
  2007年   409篇
  2006年   438篇
  2005年   373篇
  2004年   359篇
  2003年   286篇
  2002年   291篇
  2001年   312篇
  2000年   287篇
  1999年   258篇
  1998年   108篇
  1997年   104篇
  1996年   88篇
  1995年   96篇
  1994年   91篇
  1993年   95篇
  1992年   209篇
  1991年   176篇
  1990年   218篇
  1989年   208篇
  1988年   211篇
  1987年   195篇
  1986年   183篇
  1985年   172篇
  1984年   144篇
  1983年   123篇
  1982年   78篇
  1979年   118篇
  1978年   90篇
  1977年   80篇
  1975年   93篇
  1974年   91篇
  1973年   89篇
  1972年   78篇
  1971年   85篇
  1970年   83篇
  1969年   77篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
42.
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   
43.
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   
44.
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   
45.
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   
46.
47.
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   
48.
Mesenteric and retroperitoneal cysts.   总被引:10,自引:0,他引:10       下载免费PDF全文
R J Kurtz  T M Heimann  J Holt    A R Beck 《Annals of surgery》1986,203(1):109-112
Mesenteric and retroperitoneal cysts are rare intra-abdominal tumors. Ten new patients are presented as well as 152 other cases reported in the English literature. These 162 cases were then analyzed for significant trends. Patients under 10 years of age were significantly different from the older group with respect to a shorter duration of symptoms, a higher number of patients requiring an emergency operation, a lower number of recurrences and the location of the cyst. Patients with retroperitoneal cysts were more likely to have incomplete excision of the cyst and therefore had a higher incidence of recurrence. They also required marsupialization more often. Retroperitoneal cysts should be considered a different entity from mesenteric cysts even though they present clinically in a similar fashion. The outcome of surgical treatment is less satisfactory in patients with retroperitoneal cysts.  相似文献   
49.
R Hu  C Beck  Y B Chang  L J DeGroot 《Autoimmunity》1992,12(2):103-106
Inheritance of Graves' disease has been linked to the HA-DR3 gene product which may function in some specific way in antigen presentation. To determine whether the first extracellular domain of this protein, which is specifically involved in antigen presentation, has the same sequence in patients with Graves' disease and in normal individuals, we have amplified the second exon using the polymerase chain reaction, and then cloned and sequenced the DNA segment. In eight subjects with Graves' disease, sequences identical to prototypic reported sequence for DRB1*0301 were recovered, and in two individuals sequences varied by a few nucleotides, leading to 1-3 amino acid substitutions which did not occur in a pattern. Sequences identical to the prototypic sequence known as DRB3*0101, also previously known as DRw52, were also recovered. Thus the HLA-DRB1 and B3 genes present in patients with autoimmune disease appear to be the same as those present in the general population. These observations indicate that a unique allele is not present in patients with autoimmune disease, but rather that the normal DR3 allele itself, in a manner yet to be described, increases the probability of developing autoimmune thyroid disease.  相似文献   
50.
Nitric oxide (NO) is a free radical produced by several lung cells via the enzyme nitric oxide synthetase (NOS) and can be easily measured in exhaled air by chemiluminescence analysis. As the iso-enzyme iNOS may be induced by cytokines and endotoxin, NO is elevated in several chronic inflammatory airway diseases. Prior to using exhaled nitric oxide (eNO) as a non-invasive marker of airway inflammation in daily routine, the role of possibly influencing factors such as age, time of the day, smoking exposure and intra-individual variability have to be clarified. NO concentrations were measured in 107 healthy children aged 4–18 years at an expiratory flow of 184 ml/s. Spirometry and a skin-prick test were performed and a questionnaire on family history of atopy, personal symptoms of atopic disease and smoke exposure was completed. For intra-individual variability nitric oxide was measured in six children three times daily on 6 consecutive days. Median eNO concentration was 5.7 p.p.b., and increased significantly with age but did not vary with gender. No correlation was found between eNO and smoke exposure, positive skin-prick test, FEV 1, MEF25 and time of the day. There was no circadian rhythm found in the six children measured on 6 consecutive days, but the eNO showed an intra-individual coefficient of variation of 25.9%. With the help of a two-compartment model of the lung the alveolar NO concentration was estimated to be 4.1 p.p.b and was shown to be constant with age, whereas the airway part of NO steadily increased with age. When comparing eNO values with standardized measurement techniques, the age of the children and the large intra-subject coefficient of variation have to be taken into account, whereas in healthy children subject-specific factors such as atopic history, gender and skin test reactivity did not affect eNO measurement.  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