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   4673篇
  免费   237篇
  国内免费   21篇
耳鼻咽喉   90篇
儿科学   198篇
妇产科学   61篇
基础医学   468篇
口腔科学   98篇
临床医学   319篇
内科学   780篇
皮肤病学   39篇
神经病学   385篇
特种医学   332篇
外科学   896篇
综合类   125篇
预防医学   179篇
眼科学   252篇
药学   345篇
中国医学   13篇
肿瘤学   351篇
  2023年   28篇
  2022年   67篇
  2021年   178篇
  2020年   72篇
  2019年   106篇
  2018年   130篇
  2017年   96篇
  2016年   124篇
  2015年   117篇
  2014年   160篇
  2013年   226篇
  2012年   363篇
  2011年   371篇
  2010年   207篇
  2009年   208篇
  2008年   321篇
  2007年   299篇
  2006年   261篇
  2005年   254篇
  2004年   234篇
  2003年   193篇
  2002年   201篇
  2001年   74篇
  2000年   52篇
  1999年   63篇
  1998年   31篇
  1997年   22篇
  1996年   15篇
  1995年   16篇
  1993年   23篇
  1992年   36篇
  1991年   40篇
  1990年   37篇
  1989年   49篇
  1988年   31篇
  1987年   26篇
  1986年   16篇
  1985年   10篇
  1984年   11篇
  1983年   14篇
  1982年   9篇
  1981年   20篇
  1980年   10篇
  1979年   10篇
  1976年   10篇
  1975年   10篇
  1974年   7篇
  1973年   10篇
  1972年   7篇
  1971年   7篇
排序方式: 共有4931条查询结果,搜索用时 15 毫秒
1.
2.
ABSTRACT

HIV-positive men who have sex with men (HIV+MSM) in India need culturally-relevant interventions to promote safer sex. We tested a multi-level intervention among HIV+MSM that targeted individual, interpersonal, and community factors, based on the Social-Personal and Social Ecological Models. We conducted a 2?×?2 factorial RCT with 119 HIV+MSM randomised to receive either an individual-level intervention (ILI) using motivational interviewing to promote safer sex, a community-level intervention (CLI) to strengthen community norms toward safer sex and reduce stigma among MSM communities, a multi-level intervention combining the individual- and community-level interventions (ILI?+?CLI), or standard-of-care control. Participants completed pre- and post-intervention assessments of a composite sexual risk score and a process evaluation to assess fidelity and satisfaction. Out of the 119 HIV+MSM, 106 (89.0%) completed pre- and post-intervention assessments. Generalised Estimating Equation models showed that both CLI (Incidence Rate Ratio [IRR]?=?.67, 95% CI .47 to .96) and ILI?+?CLI (IRR?=?.66, 95% CI .48 to .91) groups had a statistically significant decrease in sexual risk compared to the standard-of-care. The interventions had high levels of fidelity and satisfaction. This pilot RCT demonstrated feasibility and potential effectiveness of a multi-level intervention that addresses individual, interpersonal and community-level contributors of sexual risk among HIV+MSM.  相似文献   
3.
A model is developed to describe protein release kinetics from injectable, polymer solution depots which undergo rapid phase inversion on injection. The model consists of a polymer-rich phase and a solvent-rich phase, consistent with experimentally observed phase inversion morphology. Equations in the polymer-rich phase are based on diffusion-reaction mass balances for solvent, water and dissolved drug, and the rate of dissolution of dispersed drug particles. Equations in the water-rich phase are also of the diffusion-reaction type. Transport parameters in the polymer-rich phase are coupled to the ternary thermodynamics through friction formalism, and remaining parameters are estimated from literature data, leaving two free parameters: volume fraction of water-rich phase (epsilon) and k, the mass-transfer coefficient for bath-side transfer of the protein. Variations of these parameters lead to predictions of release profiles that vary from a rapid, burst-like behavior followed by a locking-in of the polymer-rich phase, to a uniform, zero-order profile. Comparisons are made to lysozyme release data for three systems: PLGA solutions in N-methlypyrollidinone (NMP), PLA solutions in NMP, and the latter with added Pluronic. Good agreement between model predictions and data is shown; in particular, the transition from rapid release to zero-order kinetics that occurs on addition of Pluronic is illustrated.  相似文献   
4.
The aqueous extract of the fruits of Terminalia chebula Retz. has been evaluated for its antidiabetic activity in streptozotocin (STZ) induced mild diabetic rats and compared with a known drug, tolbutamide. The oral effective dose (ED) of the extract was observed to be 200 mg/kg body weight, which produced a fall of 55.6% (p<0.01) in the oral glucose tolerance test. Oral administration of ED of aqueous extract of T.chebula (AETC) daily once for two months reduced the elevated blood glucose by 43.2% (p<0.01) and significantly reduced the increase in glycosylated hemoglobin (HbA1c) (p<0.01). The same dose also showed a marked improvement in controlling the elevated blood lipids as well as decreased serum insulin levels in contrast to the untreated diabetic animals. Hepatic and skeletal muscle glycogen content decreased by 75% and 62.9% respectively in diabetic controls, these alterations were partly prevented (34.9% and 21.17%) in AETC treated group when compared to the healthy controls. The in vitro studies with pancreatic islets showed that the insulin release was nearly two times more than that in untreated diabetic animals. The treatment did not have any unfavorable effect on other blood parameters of liver and kidney function tests. LD 50 was found to be above 3 g/kg bw i.e. 15 times of ED, because there were no deaths of animals even at this dose indicating high margin of safety. These findings suggest further investigations for the possible use of the aqueous extract of fruits of T.chebula for the treatment of diabetes.  相似文献   
5.
6.
Fatigue mechanisms in normal intercostal muscle and muscle from patients with myasthenia gravis (MG) were evaluated by monitoring the compound muscle action potential (CMAP) and tetanic tension responses to repetitive nerve or muscle stimulation in vitro. When fatigue was induced by nerve stimulation at 30 Hz for 0.5 s every 2.5 s, about half of the original tension decreased after 30 min in normal muscle and 5 min in MG muscle. Analysis of the changes in area of CMAPs and tension indicated that impairment of neuromuscular transmission, muscle membrane excitation, and excitation-contraction (E-C) coupling and contractility accounted for 40%, 29%, and 31% of fatigue in normal muscle, and 83%, 0%, and 17% of fatigue in MG muscle. When fatigue was induced by muscle stimulation at 30 Hz, tension declined by a quarter after 30 min in normal muscle, but by a half after 17 min in MG muscle. Impairment of muscle membrane excitation and E-C coupling and contractility accounted for 58% and 42% of fatigue in normal muscle, and 22% and 78% of fatigue in MG muscle. Thus, fatigue of normal muscle is caused by impairment of at least four processes, and enhanced fatigue of MG muscle is caused by greater impairment of neuromuscular transmission, E-C coupling, and contractility. © 1993 John Wiley & Sons, Inc.  相似文献   
7.
OBJECTIVE: We report our experience with hand-assisted laparoscopic nephroureterectomy (HALN) for upper urinary tract transitional cell carcinoma and compare our results with a contemporary series of open nephroureterectomy (ON) performed at our institution. METHODS: Between August 1996 and May 2003, 90 patients underwent nephroureterectomy for upper-tract transitional cell carcinoma (TCC). Thirty-eight patients underwent HALN, while 52 had an ON. End-points of comparison included operative time, estimated blood loss (EBL), intraoperative and postoperative complications, length of hospital stay, pathologic grade and stage of tumor, and tumor recurrence. RESULTS: The mean patient age was 72.3 and 70.6 years in the ON and HALN groups, respectively. Mean operative duration was 243 minutes (ON) and 244 minutes (HALN), with an EBL of 478mL in the open group versus 191 mL in the hand-assisted group (P<0.001). No intraoperative complications occurred, but postoperative complications occurred in 4% and 11% of the ON and HALN groups, respectively (P=0.21). The mean hospital duration was 7.1 days (ON) versus 4.6 days (HALN) (P<0.01). No difference existed in the pathologic grade or stage distribution of urothelial tumors between the 2 groups. The mean follow-up was 51.0 months in the ON group and 31.7 months in the HALN group. Recurrence of urothelial carcinoma occurred in 50% of patients who underwent ON and 40% treated by HALN (P=0.38) at a median interval of 9.1 and 7.7 months, respectively, after surgery. CONCLUSION: Hand-assisted laparoscopic nephroureterectomy is an effective modality for the treatment of upper urinary tract urothelial carcinoma. Patients benefited from less intraoperative blood loss and a shorter hospitalization with an equivalent intermediate-term oncologic outcome compared with that of the open approach.  相似文献   
8.
Aims: To create a clinical and radiological profile of patients with symptomatic osteoarthritis of the knee in Malaysia. Methods: One hundred consecutive patients presenting with symptomatic knee osteoarthritis at a private rheumatology clinic were profiled for demographic and clinical features. Anteroposterior weight‐bearing, skyline and lateral knee X‐rays were taken. Statistical Package for Social Sciences was used for data analysis. Results: Women predominated (93%). Fifty‐eight percent of the patients reported bilateral knee pain. Difficulty in walking, climbing and squatting was high (85%, 97% and 93% respectively). Patients with knee pain had a higher BMI than controls. Radiological abnormality, related to osteoarthritis was present in 97%. Osteophytes were generally tricompartmental while joint space narrowing was less evident in the lateral tibiofemoral joint than in the medial tibiofemoral joint and the patellofemoral joint. Almost half (49%) the patients manifested radiological varus deformity The severity of radiological abnormality increased with age. Although patients with unilateral pain had milder radiological abnormality, it tended to be bilateral. Clinically detectable hip abnormality and nodal osteoarthritis were uncommon, as was radiological chondrocalcinosis. Conclusions: Patients presenting with symptomatic knee osteoarthritis to a rheumatology service had a high degree of disability, radiological abnormality and varus deformity. Radiological abnormalities were essentially bilateral and tricompartmental.  相似文献   
9.
10.
A hypothesis is put forward based on clinical observations and treatment modalities in vasomotor non-allergic rhinitis (V.M.R.) and primary atrophic rhinitis (P.A.R.). The hypothesis postulates that (1) V.M.R. and P.A.R. are two diseases at the ends of an autonomic spectrum (2) The anterior nasal aperture, its dimensions and sensory receptors play a vital role in the etiopathogenesis of both the conditions through reflex autonomic action.  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