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   4697篇
  免费   255篇
  国内免费   52篇
耳鼻咽喉   23篇
儿科学   220篇
妇产科学   175篇
基础医学   634篇
口腔科学   56篇
临床医学   477篇
内科学   1035篇
皮肤病学   97篇
神经病学   410篇
特种医学   244篇
外科学   517篇
综合类   71篇
一般理论   1篇
预防医学   391篇
眼科学   53篇
药学   299篇
中国医学   7篇
肿瘤学   294篇
  2021年   61篇
  2019年   60篇
  2018年   83篇
  2017年   44篇
  2016年   58篇
  2015年   61篇
  2014年   89篇
  2013年   137篇
  2012年   174篇
  2011年   218篇
  2010年   114篇
  2009年   119篇
  2008年   169篇
  2007年   212篇
  2006年   145篇
  2005年   172篇
  2004年   158篇
  2003年   126篇
  2002年   148篇
  2001年   162篇
  2000年   156篇
  1999年   146篇
  1998年   90篇
  1997年   63篇
  1996年   58篇
  1995年   50篇
  1994年   40篇
  1993年   54篇
  1992年   105篇
  1991年   129篇
  1990年   139篇
  1989年   111篇
  1988年   103篇
  1987年   81篇
  1986年   96篇
  1985年   91篇
  1984年   74篇
  1983年   39篇
  1982年   50篇
  1981年   45篇
  1980年   39篇
  1979年   68篇
  1978年   46篇
  1977年   64篇
  1976年   48篇
  1975年   39篇
  1974年   35篇
  1972年   42篇
  1971年   38篇
  1970年   36篇
排序方式: 共有5004条查询结果,搜索用时 31 毫秒
61.
Our initial paper discussed brain edema resulting from traumatic head injury and the need for specific and effective agents to treat the disorder and disclosed a novel approach for the discovery of a drug of this kind. The current study describes the synthesis of a series of [(2,3,9,9a-tetrahydro-3-oxo-9a-substituted-1H-fluoren-7-yl)oxy]alk anoic acids and their analogues. These compounds were evaluated in an in vitro cerebrocortical tissue slice assay for their relative potencies in inhibiting K+ + HCO3- induced swelling. Structural modification at a number of sites in the "lead" compound revealed that significant biological activity was inherent only within a very narrow range of structural types. The observation that nearly all the biological activity resided in one of the two enantiomers demonstrated the marked stereospecificity of the most active compounds. One of the most potent compounds, (R)-(+)-[(5,6-dichloro-2,3,9,9a-tetrahydro-3-oxo-9a-propyl-1H-fluoren -7-yl) oxy]acetic acid ((+)-5c), exhibited a dose-response relationship in the in vivo acceleration/deceleration brain edema assay, and the data from the two highest doses were statistically significant. Electron microscopic examination demonstrated that the perivascular astroglial swelling that arises from this procedure is abolished in the animals treated with (+)-5c. This compound is currently being evaluated for its clinical efficacy and safety in the treatment of traumatic head injury.  相似文献   
62.
63.
64.
In urgent clinical situations, such as trauma, urgent surgery or before thrombolysis, rapid quantification of direct oral anticoagulant plasma drug levels is warranted. Using the ClotPro® analyser, we assessed two novel viscoelastic tests for detection of clinically-relevant plasma drug levels in trauma patients. The ecarin clotting time was used to assess the plasma concentration of dabigatran and Russell´s viper venom clotting time to determine the plasma concentration of direct factor Xa inhibitors. In parallel, plasma concentrations were analysed using plasma-based chromogenic assays. A total of 203 simultaneous measurements were performed. Strong to very strong linear correlations were detected between ecarin clotting time and plasma concentration of dabigatran (r = 0.9693), and between Russell´s viper venom clotting time and plasma concentrations of apixaban (r = 0.7391), edoxaban (r = 0.9251) and rivaroxaban (r = 0.8792), all p < 0.001. An ecarin clotting time ≥ 189 seconds provided 100% sensitivity and 90% specificity for detecting plasma dabigatran concentrations ≥ 50 ng.ml-1. Corresponding Russell´s viper venom clotting time cut-off values were ≥ 136 seconds for apixaban (80% sensitivity, 88% specificity), ≥ 168 seconds for edoxaban (100% sensitivity, 100% specificity) and ≥ 177 seconds for rivaroxaban (90% sensitivity, 100% specificity). Detection of drug levels ≥ 100 ng.ml-1 was also investigated: for dabigatran, an ecarin clotting time ≥ 315 seconds yielded 92% sensitivity and 100% specificity; while Russell´s viper venom clotting time cut-offs of 191, 188 and 196 seconds were calculated for apixaban (67% sensitivity, 88% specificity), edoxaban (100% sensitivity, 75% specificity) and rivaroxaban (100% sensitivity, 91% specificity), respectively. We have demonstrated strong positive correlations between plasma drug levels and clotting time values in the specific ClotPro assays. Cut-off values for detecting clinically-relevant drug levels showed high levels of sensitivity and specificity.  相似文献   
65.
66.
Summary Based upon findings from 60 cadavers (120 sides), the incidence of superior laryngeal nerve loop, connecting the cervical sympathetic chain and the superior laryngeal nerve and its branches, the external and internal laryngeal nerve, was 98.3% (118 out of 120 sides). In most cases the loop connected the sympathetic chain and the external laryngeal nerve. The external laryngeal nerve was looped, and not linear as traditionally thought. The loop could be divided into three categories, V-shaped, U-shaped and mixed, and subdivided into 5 types and 17 subtypes according to morphological variation. The loop without exception innervated not only the cricothyroid muscle, but also the thyroid gland. The loop is one of the origins of the thyroid nerve. It seems that for thyroid surgery the loop, when lower in position, should be carefully separated from the superior thyroid vessels before the latter are ligated, in order to preserve a normal nerve supply to the muscle as well as to the part of the gland that remains after surgery.
L'anse du nerf larynge supérieur, étude anatomique et applications chirurgicales
Résumé La fréquence d'une anse du nerf laryngé supérieur réalisant une anastomose entre la chaine sympathique cervicale et le nerf laryngé supérieur et/ou ses branches (rameau laryngé externe et ingerne), est de 98,3 % (118/120). Ce résultat s'appuie sur l'étude de 60 cadavres. Dans la plupart des cas, l'anastomose se fait entre la chaine sympathique cervicale et le rameau laryngé externe. Ce rameau laryngé externe a un trajet curviligne et non linéaire conformément aux données classiques. Il existe trois catégories d'anses : en "V", en "U" et mixte ; on peut également les subdiviser en 5 types et 17 sous-types en fonction des variations morphologiques. Cette anse innerve constamment non seulement le muscle cricothyroïdien mais aussi la glande thyroïde dont elle fournit une partie de l'innervation. Lors de la chirurgie thyroïdienne, si l'anse est en position basse, les nerfs doivent être soigneusement disséqués et séparés des vaisseaux thyroïdiens supérieurs avant ligature de ces derniers de façon à conserver l'innervation normale du muscle et de la partie restante de la glande.
  相似文献   
67.
When should incidentalomas of the adrenal gland be surgically treated?   总被引:1,自引:0,他引:1  
U G?hring  R Ziegler  H Buhr 《Der Chirurg》1990,61(4):304-307
Between January 1981 and December 1988 a total of 95 patients underwent surgery for adrenal tumors. In 24 cases (25.3%) a so-called "incidentaloma" was found. While seven of these tumors showed hormonal activity, in seventeen patients the tumor was hormonal inactive. The size of the tumors ranged between 2 and 11 cm. Histologically all tumors were found to be benign neoplasms. Because of the lack of lethality and minimal morbidity we indicate surgery on incidentaloma of the adrenal gland for the following reasons: tumors with hormone activity, tumor size larger than 3 cm, suspecting malignoma or metastasis and finally in proven enlargement of small tumors. Only in adrenal tumors smaller than 3 cm we suggest a follow-up by ultrasound or computed tomography.  相似文献   
68.
We describe a new multipurpose method for corneal refractive surgery by using a focused excimer laser beam, which allows the application of a small, compact low-energy excimer laser. It is possible to ablate any area desired in the cornea without masking by scanning the focused beam. The ablation depths in freshly enucleated swine eyes were measured in relation to the number of laser pulses (at fixed fluence) and the pulse fluence at wavelengths = 248 nm and =193 nm. The irradiation conditions were investigated to obtain smooth ablation of the corneal material over an area of about 1 cm2. The experiments show that smooth ablation is obtained when the ratio of the excimer laser beam spot diameter on the corneal surface and the displacement for one scanning step is given by a whole number. A simple model based on rectangular beam profiles is presented to exemplify this.  相似文献   
69.
Some novel 6-fluoro-7-substituted-1,4-dihydro-4-oxoquinoline-3-carboxylic acids have been prepared. At the N-1 position "standard" substitution was employed with the ethyl, cyclopropyl, and p-fluorophenyl groups being used. At C-7 the introduction of some novel piperazines was made. Most notably, 2-(fluoromethyl)piperazine (10) and hexahydro-6-fluoro-1H-1,4-diazepine (16, fluorohomopiperazine) at the quinolone C-7 position produced products with similar in vitro antibacterial activity as the ciprofloxacin reference. The in vivo efficacy of 1-cyclopropyl-6-fluoro-7-[3-(fluoromethyl)piperazinyl]-1,4-dihydro-4- oxoquinoline-3-carboxylic acid (20) was excellent with better oral absorption than ciprofloxacin (2).  相似文献   
70.
0 引言 我科 1996 / 1998分别应用消痔灵与强的松龙混合液、消痔灵液、强的松龙液行鼻息肉内 ,鼻息肉蒂部注射治疗鼻息肉各 5 0例 ,并设对照组为鼻腔滴入及口服类固醇激素 5 0例 ,合计 2 0 0例 ,观察并对比其疗效 .1 对象和方法1.1 对象 男 12 8例 ,女 72例 ,年龄 8~ 78(平均 38)岁 ,病程 32 a~ 45 (平均 4.5 ) a.其中在本次治疗前做过一次鼻息肉摘除术后复发的 2 7例 ,做过 2次或 2次以上手术的 12例 .主要症状为鼻塞、流脓涕、头痛及嗅觉减退 .全部病例治疗前均行鼻窦 X线拍片 ,其中上颌窦炎 12 5例、筛窦炎 5 8例、蝶窦炎 2例、…  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