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   1877篇
  免费   51篇
  国内免费   33篇
耳鼻咽喉   23篇
儿科学   50篇
妇产科学   15篇
基础医学   113篇
口腔科学   57篇
临床医学   299篇
内科学   185篇
皮肤病学   29篇
神经病学   65篇
特种医学   71篇
外科学   221篇
综合类   296篇
预防医学   190篇
眼科学   18篇
药学   230篇
中国医学   28篇
肿瘤学   71篇
  2022年   2篇
  2021年   6篇
  2020年   5篇
  2019年   7篇
  2018年   3篇
  2017年   18篇
  2016年   6篇
  2015年   165篇
  2014年   197篇
  2013年   145篇
  2012年   123篇
  2011年   217篇
  2010年   89篇
  2009年   143篇
  2008年   85篇
  2007年   172篇
  2006年   106篇
  2005年   46篇
  2004年   50篇
  2003年   30篇
  2002年   24篇
  2001年   21篇
  2000年   11篇
  1999年   14篇
  1998年   13篇
  1997年   25篇
  1996年   23篇
  1995年   21篇
  1994年   19篇
  1993年   20篇
  1992年   13篇
  1991年   18篇
  1990年   12篇
  1989年   11篇
  1988年   15篇
  1987年   21篇
  1986年   15篇
  1985年   4篇
  1984年   4篇
  1983年   2篇
  1982年   9篇
  1981年   9篇
  1980年   3篇
  1979年   5篇
  1977年   2篇
  1975年   2篇
  1971年   2篇
  1956年   1篇
  1955年   1篇
  1934年   1篇
排序方式: 共有1961条查询结果,搜索用时 0 毫秒
1.
AIM: To evaluate the usefulness of urodynamic study in young men with lower urinary tract symptoms (LUTS). METHODS: We reviewed the charts of 50 men with LUTS aged 50 years and below. Those with neurological diseases, urethral trauma or strictures were excluded. All underwent multichannel urodynamic studies (UDS). The pre- and post-UDS diagnoses and treatment modalities were compared. RESULTS: Mean age was 38.1 years (17-49). The main pre-UDS diagnoses included prostatitis in seven (14%), overactive bladder in seventeen (34%) and benign prostatic hyperplasia in nine (18%). Pre-UDS management ranged from anticholingeric agents for thirteen (26%), alpha-adrenergic antagonists for nine (18%), antibiotics for six (12%). Abnormal UDS were noted in 36 (72%), including detrusor overactivity in 9 (18%), detrusor underactivity/acontractility in 5 (10%) and bladder outlet obstruction in 21 (42%). Fourteen (28%) had primary bladder neck dysfunction and five (10%) had benign prostatic hyperplasia. Post-UDS management included anticholingeric agents for ten (26%), alpha-adrenergic antagonists for seventeen (34%), catheterization for four (10%), behavioral therapy for three (6%), surgery for three (6%). None were prescribed antibiotics. Following UDS, the diagnosis had to be updated in 40 (80%) and concomitant change in management was required in 34 (68%). CONCLUSION: Young men presenting with LUTS have different underlying etiologies. Clinical diagnosis and treatment are often empiric and inaccurate. Urodynamic study is useful in the evaluation of this group of patients as it aids in arriving at an accurate diagnosis and guides treatment therapy.  相似文献   
2.
目的:采用几种不同类型的炎症动物模型对AGE的抗炎作用进行研究。方法:大鼠角叉菜胶性足肿胀,醋酸诱导的小鼠腹腔毛细血管通透性增高,小鼠羧甲基纤维素囊中的白细胞数目,大鼠巴豆油性气囊肿的形成。结果:连续灌胃给药5天,AGE(5、10g/kg)可以显著抑制角叉菜胶所致的大鼠足肿胀、醋酸所致的小鼠腹腔毛细血管通透性增高、小鼠羧甲基纤维素囊中白细胞的游出数目以及大鼠巴豆油性气囊的形成。结论:藤茶提取物具有显著的抗炎活性。  相似文献   
3.
The objective of this study is to determine whether a normal fetal morphology ultrasound scan in women older than 35 years reduces the risk of aneuploidy. We reviewed the results of amniocentesis and second trimester sonogram in all women older than 35 years from 1991 to 1995. None had prior screening. We excluded fetuses with structural anomalies. We determined the sensitivity and specificity of minor markers in detecting Down syndrome and also determined the reduction in risk of a normal sonogram. Among the 2060 women older than 35 years giving birth during the study period, 16 (0.78%) delivered an infant with Down syndrome. Of the 16 fetuses, two had no prenatal testing or ultrasound, two had invasive testing but no second trimester sonogram, five had a normal sonogram and seven had one or more sonographic markers of Down syndrome. At least 17% of women older than 35 years did not participate in prenatal testing or ultrasound. Ultrasound detected Down syndrome with a sensitivity of 59% (95% confidence interval: 45–72%), a false‐positive rate of 10.6% (9.4–11.8%) and a positive predictor value of 1 in 9. The likelihood of having normal karyotype if the sonogram was normal was 0.46 (0.31–0.61). In women older than 35 years, a normal second trimester sonogram reduces the risk of Down syndrome by more than 50%. At least 17% of women older than 35 years do not participate in prenatal testing or ultrasound.  相似文献   
4.
5.
In 10 children seriously disabled by cerebral palsy, 12 dislocated hips were surgically reduced. The main indications for surgery were impaired perineal care, decreasing sitting balance, and pain. Furthermore, the operations were considered in order to anticipate major problems in the future, such as the wind-swept hip phenomenon and pain in the hip. At follow-up, it appeared that all the children had profited from the surgical procedures.  相似文献   
6.
Reproducibility of fracture classification systems in general has been a matter of controversy. The reproducibility of spinal fracture classifications has not been sufficiently studied. We studied the inter-observer and intra-observer reproducibility of the Magerl (AO) classification using radiograms, CTs and MRIs of 53 patients. We compared this classification with the older and simpler Denis classification. Five observers classified the fractures, first using the radiograms and CTs and, 6 weeks later, with radiograms and MRIs. Three of the observers repeated the readings after 3 months. Three observers also classified the fractures according to Denis. Agreement was measured using Cohen's kappa test. The type (A, B, C) classification of the AO system was fairly reproducible with CTs. With MRI this was only moderate. Group subclassification of the types yielded higher kappa values, corresponding to substantial agreement. The agreement was, in general, better with the Denis classification, but the variance was higher due to the difficulty of finding proper categories for some injury patterns. Although the AO classification allows proper registration of all kinds of injury, the reproducibility, especially at the type level, is problematic. Use of MRI and better definition of the distinctive properties of the three different types may enhance the reproducibility of the scheme.  相似文献   
7.
The effect of H1 and H2 receptor-blocking agents on antibody-dependent cell-mediated cytotoxicity (ADCC) was studied. The H1 receptor-blocker clemastinum and the H2 receptor blocker cimetidine dose-dependently inhibited the antibody-dependent cytotoxic activity of normal human peripheral blood mononuclear cells on chicken erythrocytes. The inhibition cannot be explained either by a direct toxic effect on effector cells or by blocking of Fc receptors. The possible involvement of histamine receptor-bearing effector cells in human ADCC is suggested.  相似文献   
8.
Mouse antibodies were prepared to human amniotic fluid fibronectin by means of somatic cell hybrids. Comparison of immunological reactivity of antibodies with amniotic and plasma fibronectin revealed that the two molecules had very similar patterns of antigenic determinants. Antibodies from one cell population, however, bound belier to amniotic fluid fibronectin, indicating that there is a difference in the molecular structure of fibronectins isolated from the two sources.  相似文献   
9.
The human promyelocytic leukemia cell line HL60 can be differentiated to mature granulocytes upon exposure to DMSO (1.3%, 6 days). The ability of these cells to metabolize arachidonic acid via the 5-lipoxygenase pathway to form 5-HETE, LTB4, and 5,12-diHETEs, has been previously documented. However, the production of peptidoleukotrienes by DMSO-differentiated HL60 cells has not been previously reported. Arachidonic acid metabolites produced via 5-lipoxygenase were identified by reverse-phase, high-performance liquid chromatography, immunoreactivity specific for peptidoleukotriene, glutamyl transpeptidase transformation, characteristic UV spectra, and GC mass spectra. Leukotriene synthesis in the DMSO-differentiated HL60 cell is maximal at 5 min when stimulated with the calcium ioniphore, A23187 (1M), in the presence of calcium. These cells produce 12.94±1.8 ng/106 cells of LTC4 and 3.8±0.4 ng/106 cells of LTB4. LTC4 and LTB4 are also synthesized in the undifferentiated cell when stimulated with 1M A23187 and 1 mM Ca2+, but in much smaller quantities, i.e., 1.91±0.42 ng/106 cells of LTC4 and 0.41 ng±0.06/106 cells of LTB4. The synthetic chemotactic peptide, f-Met-Leu-Phe, also elicits formation of LTC4 and LTB4 in a dose-dependent manner in the presence of exogenously added calcium. Maximal stimulation of DMSO-differentiated cells with f-Met-Leu-Phe produces 2.5±0.2 ng of LTC4 and 1.45±0.2 ng of LTB4 per 106 cells. The observation that DMSO-differentiated HL60 cells produce LTC4, as well as other 5-lipoxygenase products, increases the utility of this cell line for unraveling the regulation of leukotriene biosynthesis by granulocytes.  相似文献   
10.
软骨组织工程中力学因素的影响及应用   总被引:1,自引:0,他引:1  
力学因素是软骨组织工程中的重要影响因素之一。近年来的研究表明,力学作用可以刺激细胞因子及激素的分泌,改变三维支架上培养的软骨细胞的新陈代谢,从而促进软骨组织的生长与重建。目前已经有诸多关于体外构建软骨组织的报道,但对于其中的力学因素的影响(包括力学因素对软骨细胞增殖的促进及力学刺激的传导机制等)还没有完全认识。就以上几方面做一综述,并简单介绍生物反应器在软骨组织工程中的应用。  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