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   2383篇
  免费   142篇
  国内免费   1篇
耳鼻咽喉   6篇
儿科学   70篇
妇产科学   34篇
基础医学   260篇
口腔科学   49篇
临床医学   322篇
内科学   385篇
皮肤病学   51篇
神经病学   164篇
特种医学   119篇
外国民族医学   2篇
外科学   306篇
综合类   90篇
预防医学   261篇
眼科学   30篇
药学   162篇
中国医学   1篇
肿瘤学   214篇
  2022年   27篇
  2021年   43篇
  2020年   34篇
  2019年   43篇
  2018年   46篇
  2017年   46篇
  2016年   38篇
  2015年   43篇
  2014年   58篇
  2013年   64篇
  2012年   96篇
  2011年   85篇
  2010年   74篇
  2009年   71篇
  2008年   93篇
  2007年   71篇
  2006年   82篇
  2005年   72篇
  2004年   65篇
  2003年   75篇
  2002年   58篇
  2001年   70篇
  2000年   67篇
  1999年   60篇
  1998年   49篇
  1997年   30篇
  1996年   49篇
  1995年   32篇
  1994年   60篇
  1993年   53篇
  1992年   67篇
  1991年   53篇
  1990年   48篇
  1989年   45篇
  1988年   44篇
  1987年   48篇
  1986年   33篇
  1985年   45篇
  1984年   35篇
  1983年   28篇
  1982年   15篇
  1981年   15篇
  1980年   19篇
  1979年   24篇
  1978年   16篇
  1976年   20篇
  1975年   16篇
  1974年   16篇
  1972年   13篇
  1970年   12篇
排序方式: 共有2526条查询结果,搜索用时 828 毫秒
81.
82.
Criteria for the classification of juvenile rheumatoid arthritis were analyzed in a detailed database of 250 children in order to assess the accuracy of diagnosis and validity of onset types and course subtypes. A number of conclusions have been derived from this study: All definitions of the 1973 criteria for classification of juvenile rheumatoid arthritis should be retained. The addition of onset types to the 1976 revision of the criteria has been validated. The course of the disease after the onset period of 6 months is as important to the outcome of a group of children as is the onset type. The current classification should be broadened to include the course subtypes.  相似文献   
83.
OBJECTIVE: To describe the effect of Etanercept treatment in systemic AA amyloidosis in tumour necrosis factor receptor-associated periodic syndrome (TRAPS). METHODS: Etanercept therapy was given to a 27 year old woman, with systemic amyloidosis and nephrotic syndrome, and to her 51 year old father, also affected by TRAPS, who had previously undergone renal transplant for amyloidosis. Serum SAA levels, plasma cytokines, glomerular filtration rate and serum amyloid P scanning were monitored. RESULTS: Etanercept treatment resulted in initial clinical resolution of nephrotic syndrome in the 27 year old female. Both subjects demonstrated improvements in GFR and initial reduction or stabilisation of amyloid deposits on SAP scanning. CONCLUSION: Etanercept may reverse or slow the progression of systemic AA amyloidosis in subjects with C33Y TNFRSF1A mutation. Treatment may however need to be continuous and life-long to prevent progression to end stage disease.  相似文献   
84.
Myocardial conduction depends on the magnitude of the fast inward sodium current as well as on cardiac fiber orientation, with more rapid propagation along myocardial fibers than across them. Although antiarrhythmic drugs depress the sodium current in a frequency-dependent fashion in vitro, their effects on conduction in the intact ventricle have been less well studied. We therefore evaluated the frequency- and orientation-dependent actions of mexiletine, quinidine, and their combination on epicardial conduction in 24 pentobarbital-anesthetized dogs. These interventions were chosen because the time constant of recovery from sodium-channel blockade by mexiletine in vitro is shorter than that from blockade by quinidine, and because we have previously shown that the combination of these drugs is often clinically effective when single-agent therapy fails. An electrode array that permitted measurement of conduction times in multiple orientations over short segments of epicardium without contamination by rapid Purkinje fiber propagation or by latency or virtual cathode effects at the stimulus site was developed for these studies. In all animals, the atrioventricular node was destroyed by injection of formalin to permit measurements over a wide range of cycle lengths (250 to 1500 msec). In the absence of drugs, conduction in any direction was frequency independent. In the presence of mexiletine, however, frequency-dependent increases in conduction times were found at cycle lengths of 600 msec or less; these changes were significantly greater in orientations for which baseline conduction was rapid. Quinidine, on the other hand, increased conduction times at all tested cycle lengths without significant orientation-dependent effects.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
85.
In order to assess the effects of free or resin-bound bile acids on colonic topography, adult rats were surgically provided with an indwelling infusion catheter in the proximal cecum, which exited at the neck behind the head. Conscious, unrestrained rats were allowed chowad libitum and were administered 1 ml of an infusion mixture twice daily for five days. The infusion mixtures included either carrier saline, 100 mg cholestyramine, 165 μmol mixed bile acids, or the bile acids bound to cholestyramine. Additional groups of rats were fed defined diets with and without 2% cholestyramine. Compared to fed controls, colonic infusions of saline had little effect on colon topography. Infusions of 100 mg of cholestyramine in saline twice each day did cause some apparent damage to surface morphology of the colon, but not to the extent observed during feeding of the resin as 2% of the diet. In contrast, extensive surface damage of the colon was observed by twice daily infusions of either 165 μmol of an equimolar mixture of cholic, deoxycholic, and chenodeoxycholic acids, or by the bile acids mixed previously with the ion-exchange resin. The data suggest that topographical damage of the colon observed during feeding of bile acid-sequestering resins is in large part due to increased concentrations of either bound or unbound bile acids in the large bowel.  相似文献   
86.
A facile single-step synthesis was performed to cross-link chitosan with thiocarbohydrazide to yield thiocarbohydrazide-chitosan (TC-Cht) which was for the first time evaluated as an inhibitor for corrosion of stainless steel in 3.5% NaCl solution. A comprehensive electrochemical analysis employing electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and cyclic voltammetry (CV) was undertaken and showed that the TC-Cht acts by adsorption on the steel surface and exhibits mixed type behavior with predominantly cathodic nature. The adsorption of TC-Cht molecules on the surface of stainless steel followed the Langmuir isotherm. The TC-Cht showed a high inhibition efficiency of >94% at 500 mg L?1 concentration. Surface investigation using SEM and EDX supported the inhibitor adsorption on the steel surface.  相似文献   
87.
88.
89.
Shotgun metagenomic sequencing (SMg) enables the simultaneous detection and characterization of viruses in human, animal and environmental samples. However, lack of sensitivity still poses a challenge and may lead to poor detection and data acquisition for detailed analysis. To improve sensitivity, we assessed a broad scope targeted sequence capture (TSC) panel (ViroCap) in both human and animal samples. Moreover, we adjusted TSC for the Oxford Nanopore MinION and compared the performance to an SMg approach. TSC on the Illumina NextSeq served as the gold standard. Overall, TSC increased the viral read count significantly in challenging human samples, with the highest genome coverage achieved using the TSC on the MinION. TSC also improved the genome coverage and sequencing depth in clinically relevant viruses in the animal samples, such as influenza A virus. However, SMg was shown to be adequate for characterizing a highly diverse animal virome. TSC on the MinION was comparable to the NextSeq and can provide a valuable alternative, offering longer reads, portability and lower initial cost. Developing new viral enrichment approaches to detect and characterize significant human and animal viruses is essential for the One Health Initiative.  相似文献   
90.
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