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   36442篇
  免费   1964篇
  国内免费   128篇
耳鼻咽喉   447篇
儿科学   2137篇
妇产科学   712篇
基础医学   4637篇
口腔科学   815篇
临床医学   2560篇
内科学   7406篇
皮肤病学   843篇
神经病学   1944篇
特种医学   804篇
外科学   5056篇
综合类   1339篇
一般理论   15篇
预防医学   2145篇
眼科学   1548篇
药学   3556篇
中国医学   275篇
肿瘤学   2295篇
  2023年   243篇
  2022年   678篇
  2021年   1169篇
  2020年   643篇
  2019年   864篇
  2018年   1069篇
  2017年   734篇
  2016年   969篇
  2015年   1010篇
  2014年   1381篇
  2013年   1840篇
  2012年   2474篇
  2011年   2462篇
  2010年   1397篇
  2009年   1266篇
  2008年   1834篇
  2007年   1761篇
  2006年   1776篇
  2005年   1398篇
  2004年   1407篇
  2003年   1194篇
  2002年   1016篇
  2001年   827篇
  2000年   874篇
  1999年   732篇
  1998年   311篇
  1997年   216篇
  1996年   223篇
  1995年   218篇
  1994年   176篇
  1993年   151篇
  1992年   499篇
  1991年   405篇
  1990年   433篇
  1989年   395篇
  1988年   357篇
  1987年   357篇
  1986年   348篇
  1985年   323篇
  1984年   262篇
  1983年   219篇
  1979年   230篇
  1978年   150篇
  1977年   180篇
  1976年   140篇
  1975年   171篇
  1974年   182篇
  1973年   182篇
  1972年   173篇
  1971年   161篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
A prospective randomized controlled study was designed to evaluate differences in efficacy and complication rate between the two most commonly used sclerosing agents, sodium tetradecyl sulfate (STD) and polidocanol. Of 52 patients with esophageal variceal bleeding, 26 were randomized to receive sclerotherapy with 1.5% STD and 26 to receive 1% polidocanol at weekly intervals. Eradication of varices was achieved in 88% patients each of the STD and polidocanol group. There was no significant difference between patients injected with STD and polidocanol with regard to re-bleeding (27% vs. 15%) and mortality (11.5% in both). The use of STD, in contrast to polidocanol, was associated with a higher incidence of complications in terms of severe retrosternal pain (27% vs. 4%), deep ulceration (53% vs. 23%), dysphagia (88% vs. 46%), and stricture formation (27% vs. 8%). It was concluded that these two agents were similar in efficacy. However, polidocanol was superior due to a lower incidence of complications.  相似文献   
62.
Standardization of allergens are achieved by in vitro and in vivo methods. Some of the allergens from Western countries are standardized using biological potency of the extracts but no attempt has been made till now to standardize any of the pollen extracts from India based on biological units. Therefore, we have attempted to standardize two important pollen allergens Ricinus communis and Holoptelea integrifolia by biological methods. Broadly the methods adopted by Dreborg and Grimmer (1983) was followed. Skin prick tests were carried out with the extracts of R. communis and H. integrifolia on 15 allergic patients in five three fold log dilutions starting with 1:10, in 50% glycerinated buffer. Glycerinated buffer (50%) and histamine dihydrochloride (1 mg/ml) were used as negative and positive controls, respectively. The mean wheal diameter obtained with different concentrations showed a gradual systematic fall with increase in dilution. The mean relative diameter (% of histamine reaction) varied from 124.1 +/- 8.9 to 33.7 +/- 6.1 and 78.9 +/- 5.5 to 21.4 +/- 3.8 with the highest and lowest concentrations of R. communis and H. integrifolia pollen antigens, respectively. The histamine equivalent concentration of antigen 1,000 Biological Units (BU) obtained for crude pollen extracts of R. communis and H. integrifolia was 1:17 and 1:22 respectively.  相似文献   
63.
BACKGROUND: Allergen extracts are unstable, heat labile or susceptible to proteases. Stability of allergen extracts is important for proper diagnosis and therapy of allergic disorders. OBJECTIVE: The present study was undertaken to determine the preservation and stabilization conditions of Imperata cylindrica (Ic) grass pollen extract. METHODS: The Ic extract was kept with 0.1 mepsilon-aminocaproic acid (EACA), 0.75 m sucrose, 5% glycerol, 0.03% human serum albumin (HSA) or 0.4% phenol for different time periods. The extracts were stored for 3, 6 and 12 months each at 4 degrees C, 4 degrees C with daily exposure to room temperature (RT) for 1 h, and RT. The quality of extracts was analysed by SDS-PAGE, Western blot, ELISA, ELISA inhibition and skin test. RESULTS: Extracts kept with EACA and sucrose retained most of the protein bands followed by glycerol as determined by SDS-PAGE and Western blot during all storage periods and conditions in comparison with standard extracts. The extracts kept with HSA, phenol and without preservative (WP) showed protein degradation below 33 kDa after 3 months storage at all conditions. However, a 67-kDa allergen was stable in these extracts. EACA extract required 75 to 120 ng of protein for 50% inhibition in IgE binding under different conditions, whereas standard extract required 70 ng for the same. ELISA also demonstrated high allergenic reactivity of EACA extract. ID test on allergy patients with EACA extract demonstrated same allergenic potency as that of standard extract. CONCLUSION: EACA is the best preservative/stabilizing agent of Ic pollen extract, followed by sucrose and glycerol. Ic extract kept with phenol, HSA and without preservative showed degradation within 3 months. EACA preserved extract is equally potent as that of standard extract up to 1 year's storage.  相似文献   
64.
65.
66.
The pattern of gastro-intestinal (GIT) and Respiratory tract (RTI) diseases in rural areas of the Varanasi district, U.P. (India) was studied from the outpatient (OPD) attendance between July 1985 to June 1986. Out of a total of new patients, 19.71% had respiratory diseases in contrast to 27.9% with GIT disease. A decreasing trend was observed in attendance rates as age advanced. The difference in age distribution of males and females was statistically significant. The attendance rates for GIT diseases were higher in female (29.16%) than in males (25.16%) whereas in RTI, the rates were higher in males (19.39%) than in females (18.77%). The attendance rate was found to be higher in rainy season (23.59%) followed by summer (14.50%). Diarrhoea (15.44%) and upper (URTI) respiratory tract infection (19.93%) occupied the major recorded episodes.  相似文献   
67.
68.
69.
Estimation of plasma cortisol by fluorometric technique desorbed by Mallingly's was carried out in 56 cases, including 38 cases of myopia (19 cases of simple myopia and 19 cases of degenerative myopia) and 18 normal individuals. Urinary 17-keto steroids/24 hours was also estimated by Zimmermann technique in 12 out of the 56 cases, which include 8 cases of myopia (4 cases of simple myopia and 4 cases of degenerative myopia) and 4 normal individuals as control. Plasma cortisol level is lower in simple and degenerative myopia than in normal subjects, but on statistical analysis the difference was not of much significance. Patients with simple myopia with positive family history showed lower value of plasma cortisol than patients with simple myopia with negative family history, the difference was also statistically insignificant (P-0.1). In degenerative myopia patients, with and without family history, there was very little difference in plasma cortisol level and statistically highly insignificant (P-0.8). Urinary 17 keto steroid/24 hour values are lower in simple and degenerative myopia than in normal subjects.  相似文献   
70.
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