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   16914篇
  免费   921篇
  国内免费   164篇
耳鼻咽喉   213篇
儿科学   324篇
妇产科学   374篇
基础医学   1937篇
口腔科学   628篇
临床医学   1309篇
内科学   4382篇
皮肤病学   212篇
神经病学   1950篇
特种医学   628篇
外科学   2808篇
综合类   39篇
一般理论   2篇
预防医学   657篇
眼科学   272篇
药学   892篇
中国医学   17篇
肿瘤学   1355篇
  2024年   10篇
  2023年   179篇
  2022年   376篇
  2021年   700篇
  2020年   415篇
  2019年   574篇
  2018年   613篇
  2017年   469篇
  2016年   519篇
  2015年   569篇
  2014年   748篇
  2013年   999篇
  2012年   1430篇
  2011年   1493篇
  2010年   783篇
  2009年   751篇
  2008年   1086篇
  2007年   1081篇
  2006年   936篇
  2005年   920篇
  2004年   897篇
  2003年   701篇
  2002年   642篇
  2001年   93篇
  2000年   56篇
  1999年   79篇
  1998年   130篇
  1997年   115篇
  1996年   86篇
  1995年   72篇
  1994年   70篇
  1993年   52篇
  1992年   38篇
  1991年   31篇
  1990年   38篇
  1989年   35篇
  1988年   18篇
  1987年   19篇
  1986年   25篇
  1985年   10篇
  1984年   18篇
  1983年   19篇
  1982年   24篇
  1981年   15篇
  1980年   18篇
  1979年   7篇
  1978年   7篇
  1976年   4篇
  1973年   3篇
  1892年   2篇
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
991.
The authors performed an anatomic study on 16 thighs of 11 fresh white cadavers at the Ludwig-Maximilian University of Munchen, Germany. They analyzed the anatomic pattern and caliber of both the lateral circumflex femoral arterial system and the perforators nourishing the anterolateral thigh flap. They found regularly a majority of musculocutaneous perforators, mainly in the central third of the thigh, arising from the descending branch of the lateral circumflex femoral artery. Despite the small number of cadavers, they identified several differences in the anatomy of the lateral circumflex femoral arterial system. These variabilities, especially regarding the descending branch and its perforators, could have clinical importance. They also suggest new dissection studies by comparing white and oriental anatomy. Their aim is to establish whether any difference in the variability of the lateral circumflex femoral arterial system could increase the popularity, currently greater in Eastern Europe, of the anterolateral thigh flap.  相似文献   
992.
So-called "skinny legs" are commonly held to be aesthetically negative in both men and women. Taking care of one's body in terms of aesthetics is a practice that is continuously spreading and being refined to the smallest details. Indeed, a leg with underdeveloped muscles, lacking a sculptured look is considered to be unattractive and therefore deserving of surgical correction. The present article illustrates a surgical technique for correcting this marginal, yet valid, aesthetic complaint as well as the relative indications, methods, and preliminary results that have been obtained in 11 patients.  相似文献   
993.
BACKGROUND AND PURPOSE: The investigation of a child with a nonpalpable testis is probably the most frequent indication for laparoscopy in pediatric patients. The objective of this study was to evaluate the results and advantages of laparoscopy-assisted orchidopexy performed without dividing the spermatic vessels. PATIENTS AND METHODS: During a 3-year period, 85 boys with nonpalpable testes (NPT) (91 testes overall) underwent laparoscopic diagnostic exploration. Twenty-five patients (27.4%) showed an intra-abdominal testis (IAT): 24 underwent a laparoscopy-assisted orchidopexy (LAO) without sectioning of the spermatic vessels, and one, whose inner spermatic vessels were not adequately long for LAO without tension, underwent a two-step Fowler-Stephens (FS) procedure. The technique consists of dissection and mobilization of the inner spermatic vessels and the vas deferens from the posterior peritoneum, sectioning of the gubernaculum attachments, and bringing down of the testis into the scrotum through the internal inguinal ring, if open, or through a neo-inguinal ring created medial to the epigastric vessels. RESULTS: Surgery lasted between 40 and 80 minutes (median 60 minutes). All the testes were brought down into the scrotum. There was only 1 (4%) intraoperative complication, which occurred in the second patient operated on with this procedure. He experienced an iatrogenic rupture of the spermatic vessels secondary to excessive traction. CONCLUSION: Laparoscopic orchidopexy is the logical extension of diagnostic laparoscopy for the evaluation of NPT. Concerning the technique, we believe that LAO with intact spermatic vessels could be considered the treatment of choice in the patient with IAT, as it does not affect normal testicular vascularization. Alternatively, in the case of very high IAT (more than 3 cm from IIR), an FS procedure may be considered.  相似文献   
994.
Hemiretinal vein occlusion associated with membranous glomerulonephritis   总被引:1,自引:0,他引:1  
PURPOSE: To report a patient in whom the finding of hemiretinal vein occlusion led to the diagnosis of membranous glomerulonephritis. DESIGN: Interventional case report. METHODS: A 44-year-old tennis instructor presented with a 1-week history of blurred vision in the left eye. Examination of the left eye demonstrated a best-corrected visual acuity of 20/40 and an inferior hemiretinal vein occlusion. RESULTS: Blood pressure was normal, and the patient was referred for a medical examination, which revealed membranous glomerulonephritis. The patient was treated with oral prednisone and cyclosporine. Four months after presentation, the left eye demonstrated resolution of the vascular abnormalities and had a best-corrected visual acuity of 20/20. CONCLUSION: Retinal vein occlusion may be associated with membranous glomerulonephritis. Treatment of the systemic disease may be associated with regression of the retinal vascular abnormalities.  相似文献   
995.
PURPOSE: To evaluate the role of retinopexy in the surgical management of primary rhegmatogenous retinal detachment (RD) without proliferative vitreoretinopathy. The primary outcome was retinal attachment, and secondary outcomes were visual acuity results and complications. METHODS: A randomized controlled trial including 60 patients with RD caused by a break or a group of breaks no larger than one clock hour. Thirty eyes received no retinopexy (group 1), and 30 eyes received transscleral cryotherapy (group 2). An encircling buckle was placed in all eyes. In eyes with posterior breaks, segmental buckles were also added. In some eyes, subretinal fluid drainage or anterior chamber paracentesis and/or intravitreal air bubble injection was performed. RESULTS: No differences were found between the groups in terms of the preoperative clinical variables evaluated: age; sex; axial length; lens status; type, number, and location of breaks; extension of detachment; and macula status. There were no differences in the surgical procedures performed. The reattachment rate in group 1 was 90%, and in group 2, it was 87% (a difference that was not significant [P = 1.00]). Final visual acuity improved by two lines or more in 22 patients in group 1 and in 20 patients in group 2 (P = 0.317). CONCLUSIONS: Our results indicate that primary rhegmatogenous RD can be successfully treated with scleral buckling without retinopexy.  相似文献   
996.
The statistical arrangement of oriented segments in natural scenes was recently proposed to be indicative of a cocircularity rule. In particular, the probability density function of the relative position of two oriented segments was found to be maximal along fixed angles on the plane, consistent with the two segments being tangent to two points of a circle. Does this observation point to a prevalence of circles in natural scenes? Here we demonstrate that similar statistics can be obtained even when circles are not very common in visual scenes. The reason is that circles or near circular objects can heavily skew the distribution in favor of the cocircularity rule.  相似文献   
997.
AIMS: To measure the unbound plasma concentrations of saquinavir (SQV) and indinavir (IDV) and to relate them to the total plasma concentrations in order to establish the unbound percentage of protease inhibitors in vivo during a full dosage interval profile. METHODS: HIV-infected subjects (n = 35; median CD4 cell count = 340 x 10(6) cells l-1, range: 120-825; viral load < 50 copies ml-1 in 22/35) treated with SQV or IDV containing regimens were studied. Plasma drug samples were collected at 0, 2, 4, 8 and 12 h postdose for the twice daily regimens and 0, 1, 2, 4 and 8 h for the three times daily regimens. Ultra-filtration was used to separate unbound IDV and SQV in plasma and their respective concentrations were measured by a fully validated method using high performance liquid chromatography-mass spectometry (h.p.l.c.-MS/MS). RESULTS: Based on the ratio AUCunbound/AUCtotal, the median unbound percentage (95% CI for differences) of SQV and IDV from all the samples studied was 1.19% (0.99, 1.58%) and 36.3% (35.1, 44.2%), respectively. No significant difference was seen in the percentage binding of SQV between patients receiving SQV alone (median = 1.49%) or with ritonavir (median = 1.09%; P = 0.141; 95% CI for difference between medians = -0.145, 0.937) over the pharmacokinetic profile. Similarly, no significant difference was seen in the percentage binding of IDV in patients receiving IDV alone (median 35.2%) or with ritonavir (median = 41.3%; P = 0.069; 95% CI for difference between medians = -0.09, 15.4). The unbound concentrations of SQV (P < 0.0001; 95% CI for r(2) = 0.634, 0.815) and IDV (P < 0.0001; 95% CI for r(2) = 0.830, 0.925) remained constant as a proportion of total concentration over the full dosing profile. CONCLUSIONS: These in vivo data confirm previously published in vitro measurements of SQV and IDV protein binding. The unbound percentage of both protease inhibitors remained constant over the dosing interval.  相似文献   
998.
Relatively little is known about occupational and other risk factors for renal-cell carcinoma (RCC). Associations between RCC and occupations, exposures and other factors were investigated in a hospital-based case-control study in Bologna (central-northern Italy). Between 1986 and 1994, 324 histologically confirmed RCC cases were diagnosed at Policlinico S. Orsola-Malpighi in patients from the Province of Bologna. Corresponding control subjects admitted to the same hospital with any diagnosis except RCC were matched for sex, age, and residency. We studied the 249 cases and 238 controls for whom detailed information on occupational history, diet, smoking habits, alcohol and drug intake was obtained. At conditional logistic regression, among males (167 matched pairs), significant matched odds ratios (OR) were found, after adjusting for cigarette smoking and alcohol intake, for high body-mass index BMI (third quartile: OR, 4.91; confidence interval [95% CI], 1.56-15.5; last quartile: OR, 4.42; 95% CI, 1.48-13.18), railway workers (OR, 10.14; 95% CI, 1.46-70.17) and asbestos exposure (OR, 7.11; 95% CI, 1.46-34.51); nearly significant OR were found for managers (OR, 3.59; 95% CI, 0.82-15.59) and metal workers (OR, 2.21; 95% CI, 0.99-5.37). Among females (52 pairs), significant OR were found for BMI > 25.4 (OR, 8.46; 95% CI, 1.02-68.0). Railway workers (on or near to trains) may have increased risk of developing RCC, possibly due to asbestos exposure. Studies are required on possible risks encountered by railway (and metal) workers and by managers.  相似文献   
999.
Atrial fibrillation (AF) is a very common arrhythmia. In order to treat acute AF rapidly, effective drug regimens are required. Propafenone is a class IC antiarrhythmic agent that is suitable for oral loading as it reaches peak plasma concentrations within 2 to 4 hours of administration. The use of propafenone loading in patients with AF must be based on appropriate patient selection in view of the negative inotropic effect and the potential proarrhythmic effects of the drug. A series of controlled trials in patients with recent-onset AF without heart failure who were hospitalised with enforced bed rest has shown that orally loaded propafenone (450 to 600 mg as single dose) exerts a relatively quick effect (within 3 to 4 hours) and a high rate of efficacy (72 to 78% within 8 hours). A potentially harmful effect of class IC agents is the risk of transforming AF into atrial flutter (3.5 to 5% of patients). However, atrial flutter with 1 : 1 atrioventricular response was observed in only two of 709 patients receiving propafenone (0.3% incidence). Nevertheless, the potential negative inotropic effect of propafenone demands careful patient selection, with systematic exclusion of patients with left ventricular dysfunction or congestive heart failure. Oral loading with propafenone can be considered as an episodic treatment in patients with AF recurrences, as has been proposed for other drugs in the past. However, the safety of oral loading with propafenone as an outpatient treatment in appropriately selected patients has to be assessed by appropriately designed prospective studies.  相似文献   
1000.
WB4101 (1)-related compounds 5-10 were synthesized, and their biological profile at alpha(1)-adrenoreceptor (AR) subtypes and 5-HT(1A) serotoninergic receptors was assessed by binding assays in Chinese hamster ovary and HeLa cell membranes expressing the human cloned receptors. Moreover, their receptor selectivity was further determined in functional experiments in isolated rat prostate (alpha(1A)), vas deferens (alpha(1A)), aorta (alpha(1D)), and spleen (alpha(1B)). In functional assays, compound 5 was the most potent at alpha(1D)-ARs with a reversed selectivity profile (alpha(1D) > alpha(1A) > alpha(1B)) relative to both prototype 1 and phendioxan (2) (alpha(1A) > alpha(1D) > alpha(1B)), whereas compound 8, bearing a carbonyl moiety at position 1, was the most potent at alpha(1A)-ARs with a selectivity profile similar to that of prototypes. The least potent of the series was the trans isomer 6, suggesting that optimum alpha(1)-AR blocking activity in this series is associated with a cis relationship between the 2-side chain and the 4-phenyl ring rather than a trans relationship as previously observed for the 2-side chain and the 3-phenyl ring in 2 and related compounds. Binding affinity results were not in complete agreement with the selectivity profiles deriving from functional experiments. Although a firm explanation was not available, neutral and negative antagonism and receptor dimerization were considered as two possibilities to account for the difference between binding and functional affinities. Finally, compound 5 was selected for a modeling study in comparison with 1, mephendioxan (3), and open phendioxan (4) to achieve information on the physicochemical interactions that account for its high affinity toward alpha(1d/D)-ARs.  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