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   184246篇
  免费   17539篇
  国内免费   11867篇
耳鼻咽喉   1650篇
儿科学   1922篇
妇产科学   2439篇
基础医学   22044篇
口腔科学   3284篇
临床医学   24178篇
内科学   26913篇
皮肤病学   2217篇
神经病学   9562篇
特种医学   6542篇
外国民族医学   98篇
外科学   18836篇
综合类   29963篇
现状与发展   39篇
一般理论   22篇
预防医学   12323篇
眼科学   4780篇
药学   19931篇
  205篇
中国医学   11117篇
肿瘤学   15587篇
  2024年   760篇
  2023年   3038篇
  2022年   7972篇
  2021年   10007篇
  2020年   7486篇
  2019年   6429篇
  2018年   6709篇
  2017年   6165篇
  2016年   5773篇
  2015年   8841篇
  2014年   10720篇
  2013年   9874篇
  2012年   14390篇
  2011年   15541篇
  2010年   9923篇
  2009年   7626篇
  2008年   10121篇
  2007年   9585篇
  2006年   9201篇
  2005年   8913篇
  2004年   5710篇
  2003年   5175篇
  2002年   4288篇
  2001年   3611篇
  2000年   3817篇
  1999年   3871篇
  1998年   2296篇
  1997年   2351篇
  1996年   1793篇
  1995年   1734篇
  1994年   1517篇
  1993年   908篇
  1992年   1282篇
  1991年   1117篇
  1990年   896篇
  1989年   843篇
  1988年   762篇
  1987年   626篇
  1986年   458篇
  1985年   396篇
  1984年   190篇
  1983年   162篇
  1982年   93篇
  1981年   123篇
  1980年   79篇
  1979年   108篇
  1978年   52篇
  1977年   51篇
  1976年   42篇
  1974年   44篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
The technique of Enzyme linked immuno-electrophoresis (ELIEP) was established to detect the specific antibody against tubercle bacilli. The results of 730 cases showed that the sensitivity of this method is 97.33%, and the specificity, 97.5%. Thus this method is more sensitive than the ELISA methods which had bean published. The manipulation of ELIEP is simple, convenient, and fast, reagent stable. This method may be used in diagnosis of tuberculosis with reliability and efficiency.  相似文献   
102.
采用平阳霉素作为诱变剂,对28例喉癌患者和23例正常人做外周血淋巴细胞染色体对诱变剂敏感性研究,结果显示喉癌患者的染色体总畸变率、每细胞染色单体断裂率(b/c值)和细胞畸变率分别为1.98%±0.05%,0.57%±0.35%和42.8%±12%。正常人则分别为0.94%±0.04%,0.28%±0.12%和27%±12%。经统计学处理,喉癌患者组与正常人组的差异有高度显著性。并结合实验结果探讨了染色体对致突变剂的敏感性与患喉癌风险的关系。  相似文献   
103.
Immunoscintigraphy with radiolabelled monoclonal antibodies is widely used to detect solid tumours, but only a few trials have been carried out concerning the specific in vivo localization of an inflammatory process. The purpose of this study was to investigate the detectability of tuberculous foci utilizing this method with radiolabelled bacillus Calmette-Guérin (BCG)-specific F(ab')2 in rabbits. All of the tuberculous lesions (n = 8) were clearly visualized on serial scintigraphy for up to 48 h after injection of the antibody. Immunohistochemical and Ziel-Neelson staining of the tuberculous lesions confirmed the presence of the tuberculous antigens and bacilli. It failed to demonstrate any sustained retention of the BCG-specific antibody fragment in the control group with syphilitic orchitis (n = 2). Therefore, the specific in vivo localization of tuberculosis is feasible by immunoscintigraphy.  相似文献   
104.
The sensitivity of alpha-naphthyl acetate esterase (ANAE) activity of human, bovine, canine, and murine leukocytes to low (42 micrograms/ml incubation mixture) and high (1.5 mg/ml incubation mixture) concentrations of sodium fluoride (NaF) was compared. The ANAE activity of bovine and canine monocytes was only slightly inhibited by the low concentration of NaF, whereas that of murine peritoneal macrophages was moderately inhibited and that of human monocytes was completely inhibited. Human and canine monocytic ANAE was completely inhibited by the high concentration of NaF, whereas the ANAE activity in 1% of bovine monocytes and murine peritoneal macrophages was not inhibited. The ANAE activity of human and murine lymphocytes in nonenriched venous blood samples showed no or negligible NaF sensitivity to the low concentration of NaF, whereas bovine lymphocytic ANAE showed slight and canine lymphocytic ANAE moderate NaF sensitivity. The ANAE of murine T-lymphoma L5178Y cells was resistant to the low concentration of NaF, but the ANAE of both murine T-lymphoma L5178Y cells and murine lymphocytes was completely inhibited by the high concentration of NaF. Human, bovine, and canine lymphocytic ANAE showed marked NaF sensitivity toward the high concentration of NaF, showing 73%, 86%, and 93% inhibition, respectively. The neutrophils in murine venous blood and ascites were positive for ANAE activity, which was only slightly inhibited by the low concentration of NaF but completely inhibited by the high concentration. Results of this investigation demonstrate that the ANAE of leukocytes of various species show remarkable differences in its sensitivity to low and high concentrations of NaF, indicating that appropriate concentrations of NaF are required for distinguishing the ANAE of lymphocytes and monocytes of different species.  相似文献   
105.
Sera from 130 first trimester pregnant women were tested for their serum antibody level against a naturally occurring serum antigen purified from non-pregnancy sera. IgG and IgM antibody level was measured using enzyme linked immunosorbant assay. Results indicate that patients with multiple abortion (n=26) have significantly (p=0.0029) lower level of IgG antibody and significantly (p=0.0001) higher level of IgM antibodies; against the serum antigen as compared to the patients with successful pregnancies with no history of miscarriage (n=63). Western blot analysis identified the scrum antigen recognized by the IgM antibody as a 24 kDa molecular mass component. These IgG and IgM antibodies may play an important role in the outcome of pregnancy.  相似文献   
106.
目的:观察体外循环(CPB)对10例瓣膜置换术病人全血细胞胰岛素受体和红细胞ATP含量的影响。方法:利用放射配体结合试验,测定全血细胞胰岛素受体密度和亲和力;用高效液相色谱法测定红细胞ATP含量,同时监测血糖和胰岛素浓度。结果:转流30分钟,血细胞高亲和胰岛素受体(R1)密度明显增加(P<0.01),亲和力(K1)明显降低(P<0.01),低亲和胰岛素受体(R2)密度也明显增加(P<0.01),但亲和力(K2)变化不大(P>0.05);停机30分钟,上述变化有所恢复,但未到转流前的水平。转流30分钟红细胞ATP含量明显降低(P<0.01),并持续到停机后30分钟,同时伴随血糖明显升高(P<0.01),胰岛素/血糖比值明显降低(P<0.01)。结论:CPB可致血细胞胰岛素受体密度增加而亲和力下降,以及红细胞ATP含量下降。  相似文献   
107.
Adenophora polysaccharides (AP), is an active principle extracted from the root of Adenophorae Potaninii Korsh originated in Gansu Province and isolated with boiling water(1). AP is isolated and purified from the crude drug by DEAE-cellulose and Sephadex G-200 column, with a white powder and mean molecular weight of 8.3 × 104 , and [α]D20of AP is 68(1). AP is only composed of glucose judging from the analysis of it with patina chromatography (PC) and gas chromatography-mass spectrometer (GC-MS) methods.The methylation analysis showed that AP is composed of (1→6) linked glucose residues. The measure of nuclear magnetic resonance imaging (NMR) 1H NMR and 14C NMR techniques further proved that AP is α(l→6) linked by Dglucose. The structure of AP is as follows: -[→6]α-D-Glu(1-)n→ (2).  相似文献   
108.
杨元  肖翠英  张思仲  张思孝  黄明孔  林立 《四川医学》2004,25(11):1166-1168
目的 探讨Y染色体无精症因子C区(azoospermia factor C,AZFe)无精症缺失基因(deleted-in-azoospermia,DAZ)家族基因拷贝缺失与中国男性原发不育之间的关系。方法 运用多重PCR与PCR-RFLP检测技术,对210例已生育男性、216例原发无精症与189例严重少精症患者Y染色体AzFc区域DAZ基因家族的基因拷贝数进行分析。结果 在所有已生育男性中未检出DAZ基因拷贝的完全或部分缺失,而在原发无精症与严重少精症患者中DAZ基因拷贝完全缺失率分别为8.8%和12.2%,DAZ1/DAZ2共缺失率分别为8.3%和5.3%。结论 在中国男性原发无精症与严重少精症患者中存在较高频率的DAZ基因拷贝缺失现象,提示Y染色体AZFc区域DAZ基因家族基因拷贝的完全与部分缺失是中国男性原发不育的遗传高风险因子。  相似文献   
109.
Primary megaureter presents a spectrum of findings ranging from mild, clinically unimportant, stable ureterectasis to severe, progressive obstructive hydroureteronephrosis. We report a patient with a double uterus and ipsilateral renal dystrophy. A previous imaging study had revealed a double uterus and obstructed left hemivagina, into which a single vaginal ectopic ureter inserted. On follow-up intravenous urography 8 years later, the left kidney was non-functioning, and there was segmental dilation of the distal right ureter. Transvaginal sonography with real-time scanning and Doppler were useful in exploring the morphological and functional status of this dilated distal ureter.  相似文献   
110.
BACKGROUND AND PURPOSE: Mycoplasma pneumoniae infection is a frequent cause of community-acquired respiratory infections in children and adults. However, standardized, rapid, specific methods for its diagnosis are lacking. The relationship between M. pneumoniae infection and asthma exacerbation has been recently discussed in the literature. We investigated the accuracy of rapid detection of mycoplasma infection by cold hemagglutination test compared to conventional enzyme immunoassays. The clinical characteristics of mycoplasma infection seen during emergent visits in asthmatic children were reviewed. METHODS: We retrospectively reviewed medical records of patients with asthma exacerbation visiting the Department of Pediatric Emergency, National Taiwan University Hospital, over a 12-month period. Subjects 2-18 years of age diagnosed with asthma at our outpatient clinic were included in this study. Patients with immunodeficiency, congenital anomalies, neurological diseases and irregular follow-up were excluded. RESULTS: A total of 269 children (174 males and 95 females) with a mean (+/- standard deviation) age of 6.15 +/- 3.08 years were included. The prevalence of asthma exacerbation in regular follow-up patients was 13.4%, and as many as 19.6% of cases (74/378 person-times) required hospitalization. Asthma attacks were most prevalent during December. 126 patients had both rapid cold hemagglutination testing and mycoplasma immunoglobulin M titers determined using acute blood samples drawn in the emergency room; 46 (36.5%) of these patients demonstrated mycoplasma infection. Sensitivity and specificity of the rapid cold hemagglutination test was 78.3% and 41.3%, respectively. The positive predictive value was 43.4%. Comparison of patients with or without mycoplasma infection revealed no differences in gender, age, chest X-ray findings, and most symptoms/signs and laboratory data, except that more signs of fever and auscultatory rales were seen in the non-mycoplasma infection group. CONCLUSIONS: Mycoplasma infections could be an exacerbating factor for asthma, and the rapid cold hemagglutination test should not be a guideline for prescribing macrolides in the emergency room.  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