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   1282842篇
  免费   122417篇
  国内免费   5721篇
耳鼻咽喉   18477篇
儿科学   35170篇
妇产科学   31617篇
基础医学   186231篇
口腔科学   40999篇
临床医学   116404篇
内科学   257151篇
皮肤病学   31917篇
神经病学   104119篇
特种医学   48550篇
外国民族医学   171篇
外科学   205611篇
综合类   31663篇
现状与发展   8篇
一般理论   308篇
预防医学   80828篇
眼科学   30337篇
药学   101436篇
  37篇
中国医学   6831篇
肿瘤学   83115篇
  2021年   10596篇
  2020年   10918篇
  2019年   19039篇
  2018年   22084篇
  2017年   20590篇
  2016年   21965篇
  2015年   23783篇
  2014年   28379篇
  2013年   35871篇
  2012年   37807篇
  2011年   38852篇
  2010年   29154篇
  2009年   24828篇
  2008年   34918篇
  2007年   35745篇
  2006年   35990篇
  2005年   33947篇
  2004年   32378篇
  2003年   31087篇
  2002年   30347篇
  2001年   73287篇
  2000年   74942篇
  1999年   61882篇
  1998年   14602篇
  1997年   12638篇
  1996年   12275篇
  1995年   11476篇
  1994年   10508篇
  1993年   9650篇
  1992年   45476篇
  1991年   43078篇
  1990年   41394篇
  1989年   40500篇
  1988年   36746篇
  1987年   35758篇
  1986年   33310篇
  1985年   31588篇
  1984年   22302篇
  1983年   18775篇
  1982年   9696篇
  1979年   19492篇
  1978年   12984篇
  1977年   11181篇
  1975年   10519篇
  1974年   12710篇
  1973年   11956篇
  1972年   11403篇
  1971年   10892篇
  1970年   10260篇
  1969年   9704篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
51.
Published data devoted to making and characterization of the properties of polymeric wound dressings with proteolytic action are reviewed. These data are indicative of individual dependence of the physicochemical properties, activity, and stability of each particular enzyme on the type of polymer matrix and the method of immobilization. In order to obtain wound dressings, which are active in physiological medium and retain their activity upon sterilization, it is necessary to optimize the composition and characteristics of a polymer matrix and the enzyme included into its structure. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 8, pp. 24–28, August, 2006.  相似文献   
52.
53.
In chronic myeloid leukaemia, CD34(+) stem/progenitor cells appear resistant to imatinib mesylate (IM) in vitro and in vivo. To investigate the underlying mechanism(s) of IM resistance, it is essential to quantify Bcr-Abl kinase status at the stem cell level. We developed a flow cytometry method to measure CrkL phosphorylation (P-CrkL) in samples with <10(4) cells. The method was first validated in wild-type (K562) and mutant (BAF3) BCR-ABL(+) as well as BCR-ABL(-) (HL60) cell lines. In response to increasing IM concentration, there was a linear reduction in P-CrkL, which was Bcr-Abl specific and correlated with known resistance. The results were comparable to those from Western blotting. The method also proved to be reproducible with small samples of normal and Ph(+) CD34(+) cells and was able to discriminate between Ph(-), sensitive and resistant Ph(+) cells. This assay should now enable investigators to unravel the mechanism(s) of IM resistance in stem cells.  相似文献   
54.
Accurate assessment of the amount and intensity of physical activity in daily life is considered very important due to the close relationship between physical activity level, health, disability and mortality. For this reason, assessment of physical activity in daily life has gained interest in recent years, especially in sedentary populations, such as patients with chronic obstructive pulmonary disease (COPD). The present article aims to compare and discuss the two kinds of instruments more commonly used to quantify the amount of physical activity performed by COPD patients in daily life: subjective methods (questionnaires, diaries) and motion sensors (electronic or mechanical methods). Their characteristics are summarised and evidence of their validity, reliability and sensitivity is discussed, when available. Subjective methods have practical value mainly in providing the patients' view on their performance in activities of daily living and functional status. However, care must be taken when using subjective methods to accurately quantify the amount of daily physical activity performed. More accurate information is likely to be available with motion sensors rather than questionnaires. The selection of which motion sensor to use for quantification of physical activity in daily life should depend mainly on the purpose of its use.  相似文献   
55.
The aim of the current study was to investigate whether alterations in N-terminal pro brain natriuretic peptide (NT-proBNP) reflect changes in right ventricular structure and function in pulmonary hypertension patients during treatment. The study consisted of 30 pulmonary hypertension patients; 15 newly diagnosed and 15 on long-term treatment. NT-proBNP, right heart catheterisation and cardiac magnetic resonance imaging measurements were performed, at baseline and follow-up. There were no significant differences between newly diagnosed patients and those on treatment at baseline or follow-up with respect to NT-proBNP, haemodynamics and right ventricular parameters. Relative changes in NT-proBNP during treatment were correlated to the relative changes in right ventricular end-diastolic volume index (r = 0.59), right ventricular mass index (r = 0.62) and right ventricular ejection fraction (r = -0.81). N-terminal pro brain natriuretic peptide measurements reflect changes in magnetic resonance imaging-measured right ventricular structure and function in pulmonary hypertension patients. An increase in N-terminal pro brain natriuretic peptide over time reflects right ventricular dilatation concomitant to hypertrophy and deterioration of systolic function.  相似文献   
56.
57.
The pharmacokinetics (PK) of moxifloxacin in healthy white New Zealand rabbits was studied following intravenous (IV) and subcutaneous (SC) administration routes as well as a SC long‐acting poloxamer 407 gel formulation (SC‐P407). Moxifloxacin concentrations were determined by high‐performance liquid chromatography assay with fluorescence detection. Mean half‐life for IV, SC and SC‐P407 routes was 2.15, 5.41 and 11.09 h. Clearance value after IV dosing was 0.78 l/kg/h. After SC administration, the mean absolute bioavailability was 117% and the Cmax was 1.61 ± 0.49 mg/l. After SC‐P407 administration, the bioavailability was 44% and the Cmax 1.83 was ±0.62 mg/l. No adverse effects were observed in any of the rabbits following IV, SC and SC‐P407 administration of moxifloxacin. Minimal inhibitory concentrations of moxifloxacin against different strains of Staphylococcus aureus from different european countries were used to compute the main pharmacodynamic (PD) surrogate markers of efficacy. The high tolerability of this SC‐P407 formulation and the favourable PK behaviour such as the long half‐life, acceptable bioavailability and excellent PK–PD ratios achieved indicate that it is likely to be effective in rabbits.  相似文献   
58.
Clinicopathological and electron microscopical findings of eight cases of enzootic nasal adenocarcinoma of sheep, diagnosed solely in one big flock in Slovenia between years 2001 and 2003 are described. All affected sheep were female, their mean age was 4.5 ± 1.5 years and they either belonged to the Istrian pramenka breed (five sheep) or were crossbreeds (three sheep). Tumours that arose from the ethmoid area of the nasal cavity were unilateral in six cases (75%) and bilateral in two cases (25%). All tumours were classified as adenocarcinomas by histopathological examination and they displayed either a combination of tubular and papillary growth or less often solely tubular proliferation. No metastases were detected in regional lymph nodes, brain or other organs. Electron microscopical studies performed on the reprocessed paraffin‐embedded tissues revealed the presence of the virus‐like particles with an average diameter between 70 and 90 nm.  相似文献   
59.
60.
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