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   15760篇
  免费   1113篇
  国内免费   70篇
耳鼻咽喉   269篇
儿科学   627篇
妇产科学   458篇
基础医学   1916篇
口腔科学   243篇
临床医学   1616篇
内科学   3537篇
皮肤病学   483篇
神经病学   1291篇
特种医学   524篇
外科学   2543篇
综合类   186篇
一般理论   20篇
预防医学   991篇
眼科学   342篇
药学   963篇
中国医学   32篇
肿瘤学   902篇
  2023年   122篇
  2022年   227篇
  2021年   588篇
  2020年   343篇
  2019年   456篇
  2018年   522篇
  2017年   379篇
  2016年   424篇
  2015年   416篇
  2014年   553篇
  2013年   742篇
  2012年   1063篇
  2011年   1083篇
  2010年   587篇
  2009年   551篇
  2008年   837篇
  2007年   923篇
  2006年   836篇
  2005年   787篇
  2004年   737篇
  2003年   629篇
  2002年   548篇
  2001年   226篇
  2000年   206篇
  1999年   213篇
  1998年   138篇
  1997年   89篇
  1996年   80篇
  1995年   67篇
  1994年   71篇
  1993年   76篇
  1992年   132篇
  1991年   136篇
  1990年   116篇
  1989年   128篇
  1988年   114篇
  1987年   108篇
  1986年   124篇
  1985年   127篇
  1984年   110篇
  1983年   87篇
  1982年   87篇
  1981年   103篇
  1980年   70篇
  1979年   90篇
  1978年   74篇
  1977年   65篇
  1975年   48篇
  1974年   54篇
  1972年   47篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Objectives: Currently in Ghana, there is an on-going task-shifting strategy in which nurses are trained in hypertension management. While this study will provide useful information on the viability of this approach, it is not clear how patients in the intervention perceive hypertension, the task-shifting strategy, and its effects on blood pressure management. The objective of this paper is to examine patients’ perceptions of hypertension and hypertension management in the context of an on-going task-shifting intervention to manage blood pressure control in Ghana.

Design: Forty-two patients participating in the Task Shifting Strategy for Hypertension program (23 males, 19 females, and mean age 61. 7 years) completed in-depth, qualitative interviews. Interviews were transcribed, and key words and phrases were extracted and coded using the PEN-3 Cultural Model as a guide through open and axial coding techniques, thus allowing rich exploration of the data.

Results: Emergent themes included patients’ perceptions of hypertension, which encompassed misperceptions of hypertension and blood pressure control. Additional themes included enablers and barriers to hypertension management, and how the intervention nurtured lifestyle change associated with blood pressure control. Primary enabling factors included the supportive nature of TASSH nurses, while notable barriers were financial constraints and difficulty accessing medication. Nurturing factors included the motivational interviewing and patient counseling which instilled confidence in the patients that they could make lasting behavior changes.

Conclusions: This study offers a unique perspective of blood pressure control by examining how patients view an on-going task-shifting initiative for hypertension management. The results of this study shed light on factors that can help and hinder individuals in low-resource settings with long-term blood pressure management.  相似文献   

2.
3.
PURPOSE: The purpose of this study was to measure spectrophotometrically the color stability of pigmented A-2186 silicone maxillofacial elastomer with 10% by volume of titanium white dry earth opacifier before and after exposure to microwave energy over a simulated 1.5-year period of microwave sterilization. Materials AND METHODS: A-2186 silicone elastomer opacified with titanium white dry earth pigment, pigmented with 5 cosmetic dry earth pigment colors [no pigment (control) group (Pc), red (Pr), yellow ochre (Py), burnt sienna (Po), and a mixture of Pr + Py + Po color group (P3)], was used in this study. Each of the 5 experimental groups consisted of 5 specimens. All specimens were placed in a 250 ml glass beaker filled with 150 ml of water (replenished for each microwave exposure). An exposure of 6 minutes was used 18 times (simulating 1.5 years of microwave sterilization with one 6 minute exposure monthly). Reflectance values were measured by spectrophotometer. Three- and two-way analyses of variance with repeated measures were performed for the color difference (DeltaE*) with the factors of group/color/months, and group/months, respectively. Means were compared by Tukey Honest Significant Difference (HSD) multiple range test calculated at the 0.05 level of significance using SPSS. RESULTS: The trained human eye can detect color changes (DeltaE*) greater than 1.0. Most DeltaE* values of the red pigment group at all intervals and the mixed pigment group at 15- and 18- month intervals increased significantly greater than 1.0 (p < 0.001) compared with the control group. Yellow and burnt sienna groups remained the most color stable over time with DeltaE* values below 0.35. CONCLUSIONS: Lack of color stability of red dry earth pigmented A-2186 silicone maxillofacial elastomers was clinically significant after 12-month exposure to microwave energy as compared with yellow, burnt sienna, and opacified A-2186 dry earth pigments.  相似文献   
4.
A novel chiral redox-active ferrocene compound (FcVI) with amphiphilic properties has been synthesized. Cryogenic Transmission Electron Microscopy (cryo-TEM) has been used to estimate the shape and size of the FcVI aggregates in solution. Uni- and multi-lamellar vesicles (between 40 and 300 nm in diameter) were observed in water. Large particles (of more than 1 μm in diameter) with a hexagonal fine structure were found in 50 mM aqueous Na2SO4 solution. Sonication transformed the latter into ‘rosette’-like structures. Cyclic voltammetry has been employed to investigate the electrochemical properties of FcVI. The amphiphile adsorbed on graphite electrodes and a reversible electrochemical behaviour, characteristic of ferrocene, was observed with redox potentials between 330 and 350 mV.  相似文献   
5.
N-Nitrosodibutylamine (NDBA) and its omega-oxidized metabolites N-nitrosobutyl-4-hydroxybutylamine (4-OH-NDBA) and N-nitrosobutyl-3-carboxypropylamine (BCPN) are potent urinary bladder carcinogens. To study putative organ specific activation of BCPN, its alpha-oxidation by liver and urinary bladder microsomal fractions was investigated in comparison to NDBA and 4-OH-NDBA. Additionally, induction of DNA single strand breaks (SSB) was monitored in hepatocytes and in a human lymphoblastoid cell line (Namalva) in the presence and absence of external metabolic activation, including N-nitroso-t-butyl-n-butylamine as a negative control. BCPN was alpha-hydroxylated and dealkylated at both alkyl chains in small rates (about 1 nmol x mg protein-1 x 60 min-1) by microsomes from rat liver and pig urinary bladder epithelium. NDBA and 4-OH-NDBA were dealkylated at similarly low rates by pig urinary bladder microsomes, in strong contrast to the high debutylation rates observed for rat liver microsomes. Correspondingly, SSB induction by NDBA and 4-OH-NDBA was observed in Namalva cells with NDBA and 4-OH-NDBA in the presence of PB-induced rat liver microsomes but not with urinary bladder microsomes or without external activation. BCPN did not induce DNA-damage in Namalva cells (with or without external activation) or in rat hepatocytes. Significant induction of sister chromatid exchanges (SCEs) and micronuclei, however, was observed in Namalva cells after incubation with NDBA and BCPN. Our data suggest activation of BCPN via alpha-oxidation in the urinary bladder, even though activation rate in-vitro is so low that a positive response is not detectable by several short-term tests.  相似文献   
6.
Bitran  Jacob D. 《JAMA》2005,293(23):2940
  相似文献   
7.
We dissected 20 preserved Caucasian cadaveric upper limbs looking at the relation of the superficial branch of the radial nerve (SBRN) to the brachioradialis tendon. SBRN emerged from deep to superficial position by piercing the brachioradialis tendon near its dorsal border in four limbs. The resulting dorsal tendinous band compressed the nerve and prevented longitudinal gliding movement during ulnar flexion. This is likely to increase the risk of chronic compression neuropathy (Wartenberg's syndrome). In two of these four limbs, there was a communication between the SBRN and lateral cutaneous nerve of the forearm. No such communication was found in the remaining 16 forearms. This communication could contribute to the minimal area of sensory loss observed in Wartenberg's syndrome. We recommend that this anatomical anomaly is looked for and if present dealt with during surgical treatment of Wartenberg's syndrome, as it is likely to predispose to chronic compression neuropathy.  相似文献   
8.
BACKGROUND: Intrahepatic stones, though common in East Asia, are uncommon in India. There is paucity of data from India regarding the treatment and long-term outcome of patients with intrahepatic stones. METHODS: We retrospectively analyzed medical records of 35 patients with intrahepatic stones who had been treated surgically. Endoscopic biliary drainage had been used in patients who presented with acute cholangitis. Intraoperative stone clearance was confirmed by choledochoscopy and intraoperative cholangiography. Outcome of surgery, frequency and subsequent management of recurrent intrahepatic stones, and factors associated with stone recurrence and cholangitis were analyzed. RESULTS: Twenty-one (60%) patients had bilobar disease. Eight patients underwent hepatectomy and 16 hepatico-jejunostomy with access loop; 12 of these were jejuno-duodenal anastomoses. Postoperative morbidity was observed in 10 patients (29%). Recurrence of stones occurred in 12 patients (34%) and cholangitis in 9 patients (26%). Presence of bilobar disease and associated biliary strictures were associated with recurrent cholangitis (p< 0.05). Two patients (6%) required re-operation for recurrent cholangitis. Complete removal of recurrent stones using conventional endoscope was possible through jejuno-duodenostomy in all 5 cases who had this type of access loop construction. CONCLUSION: Surgical treatment for intrahepatic stones depends on the site of involvement. Construction of a jejuno-duodenal access loop in patients with bilobar disease and intrahepatic strictures is helpful in facilitating postoperative stone clearance. A multidisciplinary approach is beneficial especially when the disease is bilobar and recurrent in type.  相似文献   
9.
BACKGROUND: Wall-motion analysis during low-dose dobutamine echocardiography (LDDE) is a semiquantitative measure of left ventricular contractile reserve after myocardial infarction (MI). The Doppler echocardiographic myocardial performance index (MPI) is a quantitative measure of combined left ventricular systolic and diastolic function. We sought to characterize the changes in MPI during LDDE in control subjects and patients with MI, and to describe the relation of these changes to changes in regional systolic function. METHODS: MPI was obtained at rest and during LDDE (10 microg/kg/min) in 25 healthy volunteers (group 1) and 50 patients with a recent MI. Patients were divided into two subsets; those with (n = 23; group 2A) and those without (n = 27; group 2B) a contractile reserve defined as an improvement of wall motion in more than two contiguous infarct-zone segments during LDDE. DeltaMPI was defined as the change from rest to LDDE. RESULTS: MPI decreased significantly during LDDE in groups 1 and 2A, whereas MPI increased in group 2B (DeltaMPI = 0.12 +/- 0.04 and 0.10 +/- 0.08 vs -0.03 +/- 0.08, P <.0001). On multivariate analysis, Deltawall-motion score index predicted DeltaMPI (beta = 0.65, P <.0001) independently of age, sex, and the dobutamine-induced change in heart rate and systolic blood pressure. CONCLUSIONS: Data suggest that the change in MPI during LDDE may provide a simple and quantitative measure of overall left ventricular functional reserve in patients with a recent MI.  相似文献   
10.
Despite reports demonstrating the safety of laparoscopic donor nephrectomy (LDN) for pediatric recipients of renal transplants, recent evidence has challenged using LDN for recipients 5 years of age or younger. We retrospectively reviewed the records of all pediatric recipients of living donor renal transplants from September 2000 through August 2004. We compared those who received allografts recovered by LDN (n = 34) with those recovered by open donor nephrectomy (ODN, n = 26). Outcomes of interest included operative complications, postoperative renal function, the incidence of delayed graft function or episodes of acute rejection and long-term graft function. Donor and recipient demographic data were similar for the LDN and ODN groups. Serum creatinine and calculated creatinine clearance were not significantly different between groups both in the early postoperative period and at long-term follow-up (p > 0.142). Rates of delayed graft function and acute rejection did not differ between groups. Among recipients aged 5 years old or younger stratified by donor technique (9 LDN, 5 ODN recipients), no difference was noted in graft outcomes both early and long-term (p > 0.079). At our center, pediatric LDN recipients have graft outcomes comparable to those of ODN recipients. At experienced centers, we recommend continued use of LDN for pediatric recipients of all ages.  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