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   14868篇
  免费   1197篇
  国内免费   32篇
耳鼻咽喉   171篇
儿科学   544篇
妇产科学   296篇
基础医学   2357篇
口腔科学   362篇
临床医学   1517篇
内科学   3182篇
皮肤病学   266篇
神经病学   1076篇
特种医学   600篇
外国民族医学   1篇
外科学   1996篇
综合类   104篇
一般理论   8篇
预防医学   1142篇
眼科学   328篇
药学   1163篇
中国医学   14篇
肿瘤学   970篇
  2022年   117篇
  2021年   228篇
  2020年   195篇
  2019年   246篇
  2018年   276篇
  2017年   265篇
  2016年   311篇
  2015年   285篇
  2014年   406篇
  2013年   545篇
  2012年   703篇
  2011年   667篇
  2010年   411篇
  2009年   387篇
  2008年   572篇
  2007年   609篇
  2006年   559篇
  2005年   539篇
  2004年   608篇
  2003年   502篇
  2002年   483篇
  2001年   423篇
  2000年   463篇
  1999年   408篇
  1998年   216篇
  1997年   186篇
  1996年   203篇
  1995年   177篇
  1994年   157篇
  1993年   156篇
  1992年   310篇
  1991年   345篇
  1990年   335篇
  1989年   356篇
  1988年   288篇
  1987年   296篇
  1986年   259篇
  1985年   301篇
  1984年   196篇
  1983年   168篇
  1982年   131篇
  1981年   115篇
  1980年   95篇
  1979年   170篇
  1978年   130篇
  1977年   115篇
  1976年   87篇
  1975年   106篇
  1974年   118篇
  1973年   105篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
The autopsies of 82 patients with cystic fibrosis were reviewed with respect to pathologic changes in the lungs and their respective prevalence among different age groups. Although bronchitis, mucopurulent plugging, and bronchopneumonia were almost universally present among children of all ages, epithelial metaplasia and bronchiectasis were rarer among infants and progressively more prevalent in older age groups. Emphysema was absent in patients under two years of age and affected 11 per cent of the patients two to six years of age and 40 per cent of the patients older than six years, but was never of a severe degree by the point count method. Pulmonary hemorrhage, although uncommon, was usually associated with prominent arterial vessels in walls of bronchiectatic airways. Quantitative assessment of bronchial glands revealed Reid indices significantly higher in patients with cystic fibrosis when compared to noncystic fibrosis patients, but there was no increase in these indices with the age of the patients. Glandular hypertrophy, predominance of mucous acini within glands, and goblet cell hyperplasia of the bronchial mucosa all suggest an explanation for the copious mucous secretion of patients with cystic fibrosis. However, it was not possible to ascertain whether these findings reflect a general exocrine defect of such patients or whether they were merely a response to chronic airway infection, even though the latter is a more plausible assumption.  相似文献   
82.
Parallel to the growing role of tissue engineering, the need for cell embedding materials, which allow cells to stabilise in a three-dimensional distribution, has increased. Although several substances have been tested, fibrin is thus far the only one that permits the clinical application of cultured tissue. To date, can cause severe immunological side effects. The objective of this study was to explore the practicability of obtaining autologous thrombin from a single patient in an adequate concentration and amount. Fibrinogen was cryoprecipitated from 200 ml of freshly-frozen plasma. Thrombin was isolated from the supernatant through ionexchange chromatography. The thrombin was first bound to Sephadex A-50 and then eluated using 2ml of a salt buffer (2.0M NaCl in 0.015M trisodiumcitrate, pH 7.0). The activity of the thrombin (51 NIH ml−1 to 414 NIH ml−1) reached levels comparable to those in commercially available fibrin glues (4–500 NIH ml−1). The study has shown that it is possible to obtain a sufficient amount of autologous thrombin from a single donor to create a fibrin matrix of high efficiency without the risk of immunological and infectious side effects.  相似文献   
83.
84.
85.
Glycaemic control in type 2 diabetic patients varies widely between general practitioners (GPs). To increase our understanding of this variation, linear random effects models were used to examine the predictive value of GP characteristics on the course of annual HbA1c measurements, in 688 newly diagnosed type 2 diabetic patients between one and five years after diabetes diagnosis. We found that characteristics of centrally supported GPs, such as interest in diabetes, experience, practice type, list size, and weekly working hours, did not predict their patients' glycaemic control.  相似文献   
86.
The human cytotoxic hybridoma antibody 4166 (IgMχ) was generated by fusing an in vitro EBV-transformed B-LCL from a multiparous woman with the mouse-human heteromyeloma fusion partner CB-F7. In microcytotoxicity and IIF tests with B-LCLs as target cells, the mAb 4166 was specific for DQ3 ( = DQ7 + 8 + 9). However, when used for DQ typing of class-II-positive PBMCs, 4166 could be rendered functionally specific for DQ7 + 8and did not react with DQ9+ PBMCs. Binding of mAb 4166 to DQ8-positive cells was efficiently blocked by several allotype-specific mAbs recognizing DQ8. Other HLA class-II-specific mAbs were unable to inhibit. With the use of mAb 4166, it is possible to discriminate DQ7 + 8 from DQ9 in serologic DQ typing.  相似文献   
87.
88.
89.
This study investigated the variation in freely chosen pedal rate between subjects and its possible dependence on percentage myosin heavy chain I (%MHC I) in m. vastus lateralis, maximum leg strength and power, as well as efficiency. Additionally, the hypothesis was tested that a positive correlation exists between percentage MHC I and efficiency at pre-set pedal rates but not at freely chosen pedal rate. Twenty males performed cycling at low and high submaximal power output ( approximately 40 and 70% of the power output at which maximum oxygen uptake (VO(2max)) was attained at 80 r.p.m.) with freely chosen and pre-set pedal rates (61, 88, and 115 r.p.m.). Percentage MHC I as well as leg strength and power were determined. Freely chosen pedal rate varied considerably between subjects: 56-88 r.p.m. at low and 61-102 r.p.m. at high submaximal power output. This variation was only partly explained by percentage MHC I (21-97%) as well as by leg strength and power. Interestingly, %MHC I correlated significantly with the pedal rate at which maximum peak crank power occurred (r = -0.81). As hypothesized, %MHC I and efficiency were unrelated at freely chosen pedal rate, which was in contrast to a significant correlation found at pre-set pedal rates (r = 0.61 and r = 0.57 at low and high power output, respectively). Conclusions: Subjects with high percentage MHC I chose high pedal rates close to the pedal rates at which maximum peak crank power occurred, while subjects with low percentage MHC I tended to choose lower pedal rates, favouring high efficiency. Nevertheless, the considerable variation in freely chosen pedal rate between subjects was neither fully accounted for by percentage MHC I nor by leg strength and power. Previously recognized relationships between percentage Type I ( approximately %MHC I) and efficiency as well as between pedal rate and efficiency were confirmed for pre-set pedal rates, but for freely chosen pedal rate, these variables were unrelated.  相似文献   
90.
Anti-diabetogenic effect of fusidic acid in diabetes prone BB rats.   总被引:3,自引:0,他引:3  
Fusidic acid and its sodium salt (fusidin) are anti-staphylococcal drugs. In vitro studies have shown that they prevent the lymphocyte co-stimulatory activities of the cytokines IL-1 and IL-6 in a manner similar to that of cyclosporin A, and prevent the inhibitory effect of IL-1 on glucose-induced insulin production. As IL-1 and IL-6 are thought to play a role in the pathogenesis of Type 1 diabetes, the aim of this study was to investigate whether fusidin could influence the disease incidence of the spontaneously diabetic BB rat model. Accordingly, a group of 50 BB rats receiving fusidin dissolved in their drinking water were compared to a control group of 55 rats over a period of 200 days. The incidence of diabetes was found to be 52% in the experimental group and 71% in the control group (P < 0.05). The degree of insulitis and the number of islets at histological examination were similar among the non-diabetic animals whereas the diabetic fusidin-treated animals showed a higher degree of islet preservation than the diabetic control rats. The results are highly indicative of an anti-diabetogenic effect of fusidin.  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