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   36680篇
  免费   2882篇
  国内免费   404篇
耳鼻咽喉   392篇
儿科学   1031篇
妇产科学   962篇
基础医学   4676篇
口腔科学   603篇
临床医学   3850篇
内科学   7867篇
皮肤病学   881篇
神经病学   2431篇
特种医学   1463篇
外科学   4915篇
综合类   1195篇
一般理论   32篇
预防医学   2001篇
眼科学   1588篇
药学   2761篇
中国医学   309篇
肿瘤学   3009篇
  2023年   269篇
  2022年   514篇
  2021年   964篇
  2020年   624篇
  2019年   788篇
  2018年   1014篇
  2017年   765篇
  2016年   874篇
  2015年   1056篇
  2014年   1386篇
  2013年   1674篇
  2012年   2362篇
  2011年   2466篇
  2010年   1436篇
  2009年   1287篇
  2008年   1930篇
  2007年   2041篇
  2006年   2012篇
  2005年   1945篇
  2004年   1711篇
  2003年   1593篇
  2002年   1427篇
  2001年   1131篇
  2000年   1065篇
  1999年   923篇
  1998年   425篇
  1997年   342篇
  1996年   341篇
  1995年   255篇
  1994年   246篇
  1993年   238篇
  1992年   468篇
  1991年   454篇
  1990年   439篇
  1989年   431篇
  1988年   382篇
  1987年   400篇
  1986年   363篇
  1985年   312篇
  1984年   211篇
  1983年   160篇
  1982年   107篇
  1981年   94篇
  1980年   100篇
  1979年   146篇
  1978年   101篇
  1977年   81篇
  1976年   89篇
  1975年   90篇
  1972年   69篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Summary We have completed a phase I and pharmacology study of liposomally-encapsulated daunorubicin (DaunoXome). Of 32 patients entered, 30 were evaluable. No toxicity was encountered at the initial doseescalation steps from 10 to 60 mg/m2. At 80 mg/m2, two patients manifested grade 2 neutropenia. At least grade 3 neutropenia occurred in all patients receiving 120 mg/m2. Alopecia and subjective intolerance were mild. Cardiotoxicity was not observed except for an episode of arrhythmia in a patient with lung cancer and prior radiation. Only one minor objective response was observed in this population of refractory solid tumors. Pharmacokinetics differed from those of the free drug with no detection of daunorubicinol. We recommend future phase II studies with a dose of 100 mg/m2 in previously treated and 120 mg/m2 of DaunoXome in previously untreated patients with solid tumors.EDW is supported in part by ACS award 92-14-1  相似文献   
62.
1. We studied the inhibitory effect of pituitary adenylate cyclase activating polypeptide (PACAP 1-27) on the increase in total pulmonary resistance (RL) caused either by allergen or histamine in anaesthetized, ventilated guinea-pigs. 2. PACAP 1-27 given via i.v. infusion (0.045-4.5 nmol kg-1 min-1) dose-dependently reduced the increase in RL caused by inhaled ovalbumin and histamine. At the highest dose, PACAP 1-27 prevented the increase in RL caused by ovalbumin and histamine completely. Infusion of PACAP 1-27 and the beta 2-adrenoceptor agonist, salbutamol (0.045-4.5 nmol kg-1 min-1) inhibited the increase in RL similarly, but salbutamol increased the heart rate more than PACAP 1-27. 3. PACAP 1-27 and salbutamol given via inhaled aerosol (0.1 mM, 20 breaths) significantly reduced the increase in RL caused by histamine infused i.v., whereas aerosolised sterile saline did not. Both PACAP 1-27 and salbutamol caused bronchodilator effects within 1 min of drug inhalation and these effects remained throughout the 20 min of study. 4. Because PACAP 1-27 produced significant bronchodilatation and rapid onset of sustained action in vivo and without pronounced cardiovascular side effects, we conclude that this peptide may have therapeutic potential as a bronchodilator.  相似文献   
63.
Many recent findings in Western countries suggest that episodic recall is the most sensitive discriminator between patients with mild Alzheimer disease (AD) and the normal elderly, while semantic memory tends best to differentiate between moderate and severe AD patients. The present study is the first to examine in detail the episodic memory of Chinese AD patients in Hong Kong with a locally developed list learning test, comparing procedures that do or do not encourage the use of semantic organization. The performance of 28 AD patients was compared to that of 30 normal controls. AD patients did significantly worse in terms of acquisition and retention and also benefited significantly less from external organization cues. In the discriminant function analysis, the rate of forgetting in the random condition and the total retention score in the blocked condition were found to be the best predictors for differentiating between AD patients and controls. On the other hand, in the differentiation between mild and moderate AD, semantic clustering in the blocked condition was found to be the best predictor. Results of the present study were discussed in the light of the previous findings reported in the Western countries and the neuropathological changes of AD patients.  相似文献   
64.
The mechanisms by which anti-DNA MoAbs derived from MRL-lpr/lpr mice, bind to human umbilical vein endothelial cells (HUVEC) and glomerular mesangial cells were studied using a cellular ELISA. DNAse-treatment of either the MoAb or HUVEC followed by reconstitution with DNA and/or histones was performed to determine whether DNA and histones mediated such binding. It was found that MoAb410 bound to HUVEC and mesangial cells in the form of preformed DNA/anti-DNA immune complex, and such binding was facilitated by histones. In contrast, MoAb 152 bound directly to cell membrane-associated DNA, and adding DNA to MoAb 152 reduced its cellular binding. DNA binds endothelial cell surface and histones enhance the binding of both MoAb 410 and MoAb 152 to HUVEC by increasing cell membrane-associated DNA. Finally, the degree of MoAb binding to HUVEC is critically influenced by the relative concentrations of antibody, DNA, and histones.  相似文献   
65.
G. Chan  C. K. Chan 《Hernia》2005,9(1):37-41
At the Shouldice Clinic pre-operative weight loss is used prior to incisional hernia repairs. Mesh repair is selectively used, based on specific hernia characteristics. A series of 236 patients were reviewed and followed up for 36 months. Data were available on 188 patients (80%). There were 15 recurrences (8%). The number of obese patients was reduced from 67 (35.6%) to 25 (13.3%) through the weight loss program. The hernia diameter, gastrointestinal complications, and surgical site infection were significantly related to recurrence but not the type of repair, obesity, location, or previous recurrences. The risk factors of incisional hernias include size, intestinal complications and infections. A selective use has a comparable result to the exclusive use of mesh repair. Weight reduction has yet to be shown to affect the rate of recurrence, and further prospective studies are required.  相似文献   
66.
Background and Objectives: The perception of pain is a personal experience influenced by many factors, including genetic, ethnic and cultural issues. Understanding these perceptions is especially important in dermatologic patients undergoing minor surgical operations and who often differ in their pain response to surgical treatments. Little is known about how these differences affect the perception of experimental pain. The purpose of this study was to determine experimental pain perception differences in three distinct East Asian ethnic populations.
Methods: Pain thresholds were examined with a psychophysical computerized quantitative thermal sensory testing device (TSA 2001) in healthy volunteers recruited from three different Asian ethnic groups. Using the methods of limits, experimental pain perception threshold was measured on the forehead and volar aspect of the forearm in 49 healthy subjects. The measurements were then repeated after skin barrier perturbation with adhesive tape stripping of the stratum corneum. All three ethnic groups were analyzed separately with respect to age, gender educational level and skin type.
Results: A total of 20 Chinese, 14 Malay and 15 Indian subjects completed the study. Thermal pain thresholds were similar in all three ethnic groups before and after tape strippings. No significant differences were noted between genders.
Conclusions: Using quantitative sensory thermal testing, we demonstrated that no significant differences in pain occur between different races and genders.  相似文献   
67.
Few studies used paired kidneys for comparison between tacrolimus and cyclosporine in renal transplantation. Most of the published data used whole blood trough levels for drug monitoring. However, the use of limited sampling strategy and abbreviated formula to estimate the 12-h area under concentration-time curve (AUC(0-12)) allowed better prediction of drug exposure. Sixty-six first cadaveric renal transplant recipients receiving paired kidneys were randomized to receive either tacrolimus-based (n = 33) or cyclosporine microemulsion (Neoral)-based therapies (n = 33). Abbreviated AUC(0-12) was used for drug monitoring and dose titration. Mean follow-up duration was 2.8 +/- 2 years. The patient and graft survival were comparable. Fewer incidence of acute rejection was observed in tacrolimus group (15% vs. 27.3%) though the difference was not significant (P = 0.23). The absolute value and the rate of decline of creatinine clearance were both significantly better in tacrolimus-treated patients. Prevalence of hypertension, post-transplant diabetes mellitus, infection, and malignancy were similar in both groups. Prevalence of hypercholesterolemia (11/33 vs. 4/33) and gum hypertrophy (6/33 vs. 1/33) was more common in cyclosporine-treated patients (P = 0.04 in both parameters). This was the first prospective, randomized study with paired kidney analysis showing the renal function was significantly better in tacrolimus-treated patients than in cyclosporine-treated patients.  相似文献   
68.
69.
We identified 18 patients with double-orifice mitral valve (DOMV) and intact atrioventricular (AV) septum out of 40,179 echocardiographic studies performed between 1997 and 2002 at Children's Hospital, Denver, CO. In this study we describe (1) the anatomic characteristics of the DOMV in the absence of AV septal defect, (2) the function of the mitral valve by spectral and color Doppler flow mapping, and (3) associated lesions. The topographic location of the orifices in the leaflets suggests possible embryologic mechanisms of DOMV. In this series, DOMV was most commonly associated with left-sided obstructive lesions (in 39% of patients). Spectral and color Doppler interrogation demonstrated a normal flow profile in most cases; only 2 patients had significant mitral regurgitation or stenosis. Therefore, due to the uncertain natural history of this lesion and the potential need for endocarditis prophylaxis, careful imaging of the mitral valve is recommended, particularly in the presence of left-sided obstructive lesions.  相似文献   
70.
BACKGROUND: Since 1997, a number of trials have shown promising results in treating generalized vitiligo with narrowband ultraviolet B (UVB) both in adults and children. However, there is little knowledge concerning the duration and permanency of the treatment-induced repigmentation. OBJECTIVE: Our main objective was to perform a follow-up trial of successfully treated patients receiving narrowband UVB for generalized vitiligo. METHODS: We have investigated to what degree the treatment-induced repigmentation remains stable for up to 2 years post-treatment. We performed an initial open trial including 31 patients with generalized vitiligo. They received narrowband UVB thrice weekly for up to 12 months. Patients experiencing > 75% repigmentation were defined responders and were included in the follow-up trial. Responders were followed every 6 months for up to 2 years after cessation of treatment. We observed the pigmentation status and registered any changes indicating loss of pigmentation and relapse. RESULTS: Eleven of the 31 treated patients were included in the follow-up trial. Six patients had relapse and five patients had stable response 24 months after cessation of treatment. Four out of six relapses were within 6 months post-treatment. CONCLUSION: In our study population of 31 patients with generalized vitiligo, five patients (16%) experienced > 75% stable repigmentation 2 years after cessation of a treatment programme of up to 1 years narrowband UVB therapy.  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