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   202489篇
  免费   18465篇
  国内免费   11714篇
耳鼻咽喉   1729篇
儿科学   2158篇
妇产科学   2494篇
基础医学   23164篇
口腔科学   3721篇
临床医学   26474篇
内科学   28508篇
皮肤病学   2345篇
神经病学   10002篇
特种医学   7043篇
外国民族医学   97篇
外科学   20279篇
综合类   33650篇
现状与发展   44篇
一般理论   22篇
预防医学   14566篇
眼科学   5035篇
药学   21418篇
  271篇
中国医学   12822篇
肿瘤学   16826篇
  2025年   56篇
  2024年   2931篇
  2023年   4032篇
  2022年   8350篇
  2021年   10371篇
  2020年   8310篇
  2019年   7045篇
  2018年   6935篇
  2017年   6564篇
  2016年   6150篇
  2015年   9349篇
  2014年   11497篇
  2013年   10979篇
  2012年   16012篇
  2011年   17379篇
  2010年   11481篇
  2009年   8886篇
  2008年   11363篇
  2007年   10585篇
  2006年   9949篇
  2005年   9353篇
  2004年   5952篇
  2003年   5307篇
  2002年   4350篇
  2001年   3650篇
  2000年   3840篇
  1999年   3852篇
  1998年   2291篇
  1997年   2345篇
  1996年   1797篇
  1995年   1736篇
  1994年   1518篇
  1993年   914篇
  1992年   1280篇
  1991年   1118篇
  1990年   896篇
  1989年   846篇
  1988年   766篇
  1987年   627篇
  1986年   463篇
  1985年   403篇
  1984年   192篇
  1983年   164篇
  1982年   94篇
  1981年   125篇
  1980年   80篇
  1979年   109篇
  1978年   52篇
  1977年   53篇
  1974年   44篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Conventionally a confidence interval (CI) for the standardized mortality ratio is set using the conservative CI for a Poisson expectation, μ. Employing the mid-P argument we present alternative CIs that are shorter than the conventional ones. The mid-P intervals do not guarantee the nominal confidence level, but the true coverage probability is only lower than the nominal level for a few short ranges of μ. The implications for mid-P confidence intervals of various proposed definitions of two-sided tests for discrete data are discussed.  相似文献   
92.
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   
93.
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   
94.
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   
95.
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   
96.
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   
97.
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   
98.
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   
99.
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   
100.
臀肌挛缩症(gluteal muscle contracture,GMC)是由多种原因引起的臀肌及其筋膜纤维变性、挛缩,导致髋关节功能受限所表现的特有步态、体征的临床综合征。1989年陆裕朴在国内已有系统回顾后,我国病例报道逐渐增多,普及各大省市,特别是那些偏远的山区或基层农村。由于医疗卫生条件差,再加上人们的医疗卫生、保健知识缺乏,导致对本病的认识不足,该病的发病率农村明显的高于城镇。轻者造成患儿异常姿势和特殊步态。严重的可导致骨关节畸形、骨盆倾斜、跛行等。影响患者的正常发育及生活能力。  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