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   13678篇
  免费   1021篇
  国内免费   78篇
耳鼻咽喉   168篇
儿科学   310篇
妇产科学   418篇
基础医学   1972篇
口腔科学   297篇
临床医学   1333篇
内科学   3149篇
皮肤病学   194篇
神经病学   1114篇
特种医学   603篇
外科学   1876篇
综合类   241篇
现状与发展   1篇
一般理论   14篇
预防医学   888篇
眼科学   376篇
药学   834篇
中国医学   45篇
肿瘤学   944篇
  2023年   116篇
  2022年   242篇
  2021年   401篇
  2020年   242篇
  2019年   382篇
  2018年   445篇
  2017年   288篇
  2016年   320篇
  2015年   479篇
  2014年   505篇
  2013年   653篇
  2012年   927篇
  2011年   969篇
  2010年   507篇
  2009年   458篇
  2008年   733篇
  2007年   801篇
  2006年   696篇
  2005年   700篇
  2004年   706篇
  2003年   710篇
  2002年   659篇
  2001年   265篇
  2000年   226篇
  1999年   195篇
  1998年   134篇
  1997年   107篇
  1996年   95篇
  1995年   89篇
  1994年   81篇
  1993年   86篇
  1992年   132篇
  1991年   105篇
  1990年   98篇
  1989年   103篇
  1988年   95篇
  1987年   106篇
  1986年   78篇
  1985年   56篇
  1984年   56篇
  1983年   53篇
  1982年   48篇
  1981年   43篇
  1979年   47篇
  1978年   39篇
  1977年   40篇
  1976年   34篇
  1974年   35篇
  1973年   38篇
  1972年   33篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
This study, evaluating the effects of hyperthyroidism (HT) in oesophageal motility, depended on an oesophageal radionuclide transit test. A modified standard method was used to calculate: (a) total mean transit time (MTT), (b) residual fraction (RF) and (c) retrograde index (RI) in a supine position. Eighteen untreated patients with HT and 25 normal volunteers (NV) with a similar age distribution were included in this study. The results showed that oesophageal motility in patients with HT was worse than in the normal controls (P < 0.05 by Student's t-test). The correlation of MTT, RF and RI with size and function of thyroid glands in the patients with HT were calculated to explain the effects of HT in oesophageal motility. The results showed that neither the size nor the function of the thyroid glands in HT affected oesophageal motility.  相似文献   
42.
43.
44.
An increasing number of genetic association studies have implicated polymorphisms of cytokine genes as host genetic factors influencing susceptibility to infectious disease, primarily using a candidate gene approach based on knowledge of disease pathogenesis. The application and limitations of association studies are reviewed together with the impact of recent advances in single nucleotide polymorphism mapping on strategic approaches to defining genetic susceptibility loci. It often remains unclear whether associated genetic polymorphisms are themselves functionally relevant or acting only as markers within an extended haplotype, and experimental approaches to investigating the functional impact of polymorphisms in noncoding regulatory DNA sequences are discussed. An overview of genetic associations of cytokine genes with infectious disease is presented, together with discussion of recent studies in a number of infectious diseases including hepatitis, HIV, malaria, and sepsis.  相似文献   
45.
Plasma lipid concentrations and high density lipoprotein (HDL) subclass distributions were evaluated in 22 newborn infants nourished with intravenous (iv)-fat. The majority of infants were premature with respiratory distress syndrome. Based on baseline (prior to iv-fat) HDL subclass profiles determined by gradient gel electrophoresis (GGE), infants fell into two classes, one with two or more pronounced peaks within the normal HDL spectrum (group I, 17 subjects) and the other with highly unusual HDL distribution (group II, five subjects). Total plasma cholesterol increased in both groups during low and high fat intravenous feeding. HDL-cholesterol, however, did not change with iv-fat where mean values for groups I and II at baseline, iv-low fat and -high fat were: group I, 31.2 +/- 7.1, 30.0 +/- 8.8, and 36.6 +/- 16.7 mg/dl, respectively; and group II, 20.0 +/- 7.8, 20.2 +/- 7.4, and 19.8 +/- 8.8 mg/dl, respectively. Unlike HDL-cholesterol levels that remained constant with iv-fat, apolipoprotein (apo) AI concentrations increased significantly: group I, 73.0 +/- 11.0, 88.3 +/- 15.9, and 93.1 +/- 21.9 mg/dl, respectively; and group II, 31.8 +/- 10.5, 41.0 +/- 12.8, and 59.3 +/- 18.5 mg/dl, respectively. In group I infants, iv-fat is associated with an increase in larger-sized particles, particularly in the (HDL2b)gge range; in group II there is an increase in (HDL3b)gge and (HDL3c)gge components and a disappearance of particles that fall outside of the size range of normal HDL. In both groups, enteral feeding is associated with a further normalization of HDL subclass distribution. The aberrant GGE profiles and very low apoAI levels of group II infants at baseline were associated with unusual HDL morphology determined by electron microscopy where discoidal structures were prominent. With iv-fat, discoidal particles decline in number while normal spherical structures increase. Prevalence of discoidal HDL at baseline was associated with low concentrations of lecithin:cholesterol acyltransferase (LCAT) (1.12 +/- 0.5 micrograms/ml); with iv-fat this enzyme rose to 1.61 +/- 0.18 micrograms/ml. Increased LCAT is associated with the normalization of HDL morphology. It is likely that iv-fat improves the nutritional status of premature infants, thereby stimulating increased liver synthesis of important proteins, including apoAI and LCAT, associated with HDL metabolism.  相似文献   
46.
47.
用国产恩威牌洁尔阴对阴道常见七种细菌进行抑菌试验,结果该药对其中五种细菌有明显抑菌作用,本文为洁尔阴治疗细菌性阴道炎提供了实验依据。  相似文献   
48.
Sympathetic skin response (SSR) and R–R interval variation (RRIV) were studied in 36 chronic, nondiabetic uremics to compare with their nerve conduction studies (NCS) and clinical dysautonomia. Abnormal SSR was noted in 5 (13.9%) patients, abnormal RRIV in 14 (38.9%), and abnormal NCS in 26 (72.2%). The patients were classified into three groups: group (GP) 1: “normal,” n = 21 (58.3%), normal RRIV and SSR; GP 2: “isolated parasympathetic dysfunction,” n = 10 (27.8%), abnormal RRIV and normal SSR; and GP 3: “sympathetic sudomotor dysfunction,” n = 5 (13.9%), abnormal SSR. A significant difference in age was found among the three groups (GP 3 > GP 2 > GP 1; P < 0.0001, ANOVA). After controlling the age factor, we still noted a tendency toward increasing NCS disturbances (distal latency and nerve conduction velocity of peroneal nerve; P < 0.05, multiple regression analysis) and frequencies of clinical autonomic symptoms (postural dizziness and impotence; P < 0.05, Mantel–Hanszel test) from GP 1 to GP 3. Patients with abnormal SSR (GP 3) displayed significantly higher frequencies of postural dizziness and impotence, indicating the relationship between an absence of SSR and clinical dysautonomia. © 1994 John Wiley & Sons, Inc.  相似文献   
49.
Many current generativist theorists suggest that young children possess the grammatical principles of inversion required for question formation but make errors because they find it difficult to learn language-specific rules about how inversion applies. The present study analyzed longitudinal spontaneous sampled data from twelve 2-3-year-old English speaking children and the intensive diary data of 1 child (age 2;7 [years;months] to 2;11) in order to test some of these theories. The results indicated significantly different rates of error use across different auxiliaries. In particular, error rates differed across 2 forms of the same auxiliary subtype (e.g., auxiliary is vs. are), and auxiliary DO and modal auxiliaries attracted significantly higher rates of errors of inversion than other auxiliaries. The authors concluded that current generativist theories might have problems explaining the patterning of errors seen in children's questions, which might be more consistent with a constructivist account of development. However, constructivists need to devise more precise predictions in order to fully explain the acquisition of questions.  相似文献   
50.
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