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   11082篇
  免费   696篇
  国内免费   53篇
耳鼻咽喉   303篇
儿科学   277篇
妇产科学   301篇
基础医学   1566篇
口腔科学   420篇
临床医学   915篇
内科学   2582篇
皮肤病学   232篇
神经病学   1252篇
特种医学   220篇
外科学   1005篇
综合类   21篇
一般理论   5篇
预防医学   645篇
眼科学   132篇
药学   690篇
中国医学   36篇
肿瘤学   1229篇
  2024年   19篇
  2023年   116篇
  2022年   275篇
  2021年   424篇
  2020年   271篇
  2019年   316篇
  2018年   352篇
  2017年   288篇
  2016年   349篇
  2015年   371篇
  2014年   495篇
  2013年   603篇
  2012年   924篇
  2011年   1042篇
  2010年   517篇
  2009年   449篇
  2008年   784篇
  2007年   714篇
  2006年   640篇
  2005年   670篇
  2004年   602篇
  2003年   550篇
  2002年   482篇
  2001年   60篇
  2000年   38篇
  1999年   53篇
  1998年   87篇
  1997年   60篇
  1996年   45篇
  1995年   46篇
  1994年   34篇
  1993年   32篇
  1992年   20篇
  1991年   11篇
  1990年   10篇
  1989年   15篇
  1988年   7篇
  1987年   2篇
  1986年   13篇
  1985年   3篇
  1984年   6篇
  1983年   4篇
  1982年   5篇
  1981年   4篇
  1980年   6篇
  1979年   4篇
  1978年   3篇
  1976年   3篇
  1974年   2篇
  1973年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
OBJECTIVES: To compare the efficacy of bicalutamide monotherapy to maximal androgen blockade in advanced prostatic cancer. PATIENTS AND METHODS: Previously untreated patients with histologically proven stage C or D (American Urological Association Staging System) disease were randomly allocated to either bicalutamide (B) or goserelin plus flutamide (G+F). After disease progression, patients treated with B were assigned to castration. The primary endpoint for this trial was overall survival. Prostate cancer-specific survival and progression were included among secondary endpoints. RESULTS: In total 108 patients received B and 112 received G+F. At a median follow-up time of 54 months (range 1-89), 151 patients progressed and 113 died. There was no significant difference in the duration of either progression-free or overall survival. Hazards of progression, death and cancer-specific death, corrected by disease stage, tumor grade and baseline PSA level, showed that patients initially assigned to B had a higher risk of progression but a comparable risk of death and cancer-specific death with the exception of patients with G3 tumors who had an increased risk of death). CONCLUSIONS: In patients with well or moderately well differentiated tumors, B monotherapy followed by castration may offer the same survival chance as maximal androgen deprivation. In those patients it thus represents a reasonable choice that can avoid the side effects of androgen deprivation for considerable periods of time.  相似文献   
82.
The aim of this study was to evaluate the influence of laparoscopic Palomo varicocelectomy on testicular volume and sperm parameters. Laparoscopic Palomo varicocelectomy was performed on 91 patients for left-sided grade II and grade III varicoceles. Ultrasound-derived testicular volumes, semen volume, sperm concentration, percentage sperm motility and total motile sperm count were compared before and after the procedure. Postoperative complications and recurrence rate were also assessed. There were no surgical complications. Four patients (5%) had a mild hydrocele, but did not need hydrocelectomy. No patients presented signs of testicular atrophy and the left testicular volume increased in the adolescents (p < 0.05), but not in the adults. Our data suggest that laparoscopic high mass ligation of both the testicular artery and vein is a highly effective, reliable method for the treatment of varicocele. It is associated with very low complication and recurrence rates and with an objective improvement in fertility parameters.  相似文献   
83.
Sodium-sensitive hypertension is thought to be dependent on primary alterations in renal tubular sodium reabsorption. The major apical plasma membrane Na(+) transporters include the proximal tubular Na(+)-H(+) exchanger, the thick ascending limb Na(+)-K(+)-2Cl(-) cotransport system, the distal tubular Na(+)-Cl(-) cotransporter, and the collecting duct epithelial sodium channel (ENaC). This article explores the role of each transporter in the pathogenesis of hypertension. Although the contribution of the proximal tubule Na(+)-H(+) exchanger is not yet defined completely, more convincing data have been generated about the importance of the Na(+)-K(+)-2Cl(-). Indeed at least 2 forms of hypertension appear to be related to the up-regulation of the transporter: the so-called programmed hypertension induced by low-protein diet during pregnancy and the early phase of hypertension in the Milan strain of rats. With respect to the Na(+)-Cl(-) cotransporter this may be overactive caused by inactivating mutation of WNK4 as in the Gordon syndrome, although it is the main actor for the maintenance phase of the hypertension found in the Milan strain of rats. Finally, the contribution of the ENaC has been established clearly; indeed, in the Liddle syndrome the mutation of the ENaC gene leads to a longer retention of the channel on the cell surface of collecting duct principal cells, thus inducing stronger sodium reabsorption along this segment. All these examples clearly indicate that renal sodium transporters may be responsible for various types of sodium-sensitive hypertension.  相似文献   
84.
Both genetics and physical activity (PA) contribute to bone mineral density (BMD), but it is unknown if the benefits of physical activity on childhood bone accretion depend on genetic risk. We, therefore, aimed to determine if PA influenced the effect of bone fragility genetic variants on BMD in childhood. Our sample comprised US children of European ancestry enrolled in the Bone Mineral Density in Childhood Study (N = 918, aged 5 to 19 years, and 52.4% female). We used a questionnaire to estimate hours per day spent in total, high‐, and low‐impact PA. We calculated a BMD genetic score (% BMD lowering alleles) using adult genome‐wide association study (GWAS)‐implicated BMD variants. We used dual‐energy X‐ray absorptiometry to estimate femoral neck, total hip, and spine areal‐BMD and total body less head (TBLH) bone mineral content (BMC) Z‐scores. The BMD genetic score was negatively associated with each bone Z‐score (eg, TBLH‐BMC: estimate = –0.03, p = 1.3 × 10?6). Total PA was positively associated with bone Z‐scores; these associations were driven by time spent in high‐impact PA (eg, TBLH‐BMC: estimate = 0.05, p = 4.0 × 10?10) and were observed even for children with lower than average bone Z‐scores. We found no evidence of PA‐adult genetic score interactions (p interaction > 0.05) at any skeletal site, and there was no evidence of PA‐genetic score–Tanner stage interactions at any skeletal site (p interaction > 0.05). However, exploratory analyses at the individual variant level revealed that PA statistically interacted with rs2887571 (ERC1/WNT5B) to influence TBLH‐BMC in males (p interaction = 7.1 × 10?5), where PA was associated with higher TBLH‐BMC Z‐score among the BMD‐lowering allele carriers (rs2887571 AA homozygotes: estimate = 0.08 [95% CI 0.06, 0.11], p = 2.7 × 10?9). In conclusion, the beneficial effect of PA on bone, especially high‐impact PA, applies to the average child and those genetically predisposed to lower adult BMD (based on GWAS‐implicated BMD variants). Independent replication of our exploratory individual variant findings is warranted. © 2016 American Society for Bone and Mineral Research.  相似文献   
85.

Aim

Surgical myotomy of the lower esophageal sphincter has a 5-year success rate of approximately 91 %. Peroral endoscopic myotomy can provide similar results for controlling dysphagia. Some patients experience either persistent or recurrent dysphagia after myotomy. We present here a retrospective analysis of our experience with redo myotomy for recurrent dysphagia in patients with achalasia.

Methods

From March 1996 to February 2015, 234 myotomies for primary or recurrent achalasia were performed in our center. Fifteen patients (6.4 %) had had a previous myotomy and were undergoing surgical redo myotomy (n?=?9) or endoscopic redo myotomy (n?=?6) for recurrent symptoms.

Results

Patients presented at a median of 10.4 months after previous myotomy. Median preoperative Eckardt score was 6. Among the nine patients undergoing surgical myotomy, three esophageal perforations occurred intraoperatively (all repaired immediately). Surgery lasted 111 and 62 min on average (median) in the surgical and peroral endoscopic myotomy (POEM) groups, respectively. No postoperative complications occurred in either group. Median postoperative stay was 3 and 2.5 days in the surgical and POEM groups, respectively. In the surgical group, Eckardt score was <3 for seven out of nine patients after a mean follow-up of 19 months; it was <3 for all six patients in the POEM group after a mean follow-up of 5 months.

Conclusions

A redo myotomy should be considered in patients who underwent myotomy for achalasia and presenting with recurrent dysphagia. Preliminary results using POEM indicate that the technique can be safely used in patients who have undergone previous surgical myotomy.
  相似文献   
86.

Background

Sentinel lymph node biopsy (SLNB) allows for staging of the axillary node status in early-stage breast cancer (BC) patients and avoiding complete axillary lymph node dissection (ALND) when the sentinel lymph node (SLN) is proven to be free of disease. In a previous randomized trial we compared SLNB followed by ALND (ALND arm) with SLNB followed by ALND only if the SLN presented metastasis (SLNB arm). At a mid-term of ≈ 6 years median follow-up, the two strategies appeared to ensure similar survival and locoregional control. We have revised these previous findings and update the results following a 15-year observation period.

Methods

Patients were randomly assigned to either the ALND or SLNB arm. The main endpoints were event-free survival (EFS), overall survival (OS), and axillary disease recurrence. EFS and OS were assessed using Kaplan–Meier analysis and the log-rank test.

Results

The ALND and SLNB arms included 115 and 110 patients, respectively. At 14.3 years median follow-up, 39 primary BC-related recurrences occurred, 22 (19 %) of which occurred in the ALND arm and 17 (16 %) occurred in the SLNB arm (p = 0.519). No axillary relapse developed in the SLNB arm, while two were observed in the ALND arm. OS (82.0 vs. 78.8 %) and EFS (72.8 vs. 72.9 %) were not statistically different between the ALND and SLNB arms (p = 0.502 and 0.953, respectively).

Conclusions

SLNB is a safe and efficacious component of the surgical treatment of early-stage BC patients. In the long-term, SLNB is equivalent to ALND in terms of locoregional nodal disease control and survival in this subset of patients.
  相似文献   
87.
CONTEXT AND OBJECTIVE: The choice of an antihypertensive drug is based on several criteria and specific situations give rise to doubt and controversy. The aim here was to evaluate physicians approaches towards treatment with antihypertensive agents in specific situations. DESIGN AND SETTING: Cross-sectional study, at Universidade Federal de S?o Paulo, S?o Paulo. METHODS: A questionnaire was applied during a nephrology meeting to evaluate individual approaches towards each hypothetical clinical situation. The questionnaire consisted of five multiple-choice questions (clinical cases) concerning controversial aspects of antihypertensive therapy. RESULTS: A total of 165 questionnaires were analyzed. Most participants were nephrologists (93.2%). There was a preference for angiotensin-converting enzyme (ACE) inhibitors in at least two of the cases. Only 57.2% of the physicians were correct in choosing beta-blockers as the first-line drugs for patients with ischemic coronary disease. Moreover, 66.2% chose ACE inhibitors as the first-line drugs for patients with chronic kidney disease and proteinuria. About 5% of the physicians did not follow the current recommendations for the use of ACE inhibitors in diabetic patients with microalbuminuria. The most controversial question concerned the first-line drug for advanced chronic kidney disease. Most physicians were correct in choosing calcium channel blockers and avoiding ACE inhibitors in renovascular hypertension in the case of a patient with a single functioning kidney. CONCLUSIONS: Most physicians adopted the correct approach, but some had an alternative strategy for the same situations that was not based on evidence.  相似文献   
88.
Context  Immunization with a meningococcal tetravalent (serogroup ACWY) glycoconjugate vaccine is recommended for all US adolescents. However, the currently licensed vaccine is poorly immunogenic in infancy, when the highest rates of disease are observed. Objective  To determine the immunogenicity of a novel tetravalent CRM197-conjugated meningococcal vaccine (MenACWY) in infants. Design, Setting, and Participants  Randomized, open-label, controlled study of 225 UK and 196 Canadian 2-month-olds from August 2004 to September 2006. Intervention  UK infants received a primary course of MenACWY (at 2, 3, and 4 months or 2 and 4 months) or Neisseria meningitidis serogroup C monovalent meningococcal glycoconjugate vaccine (MenC) (at 2 and 4 months). All received MenACWY at 12 months. Canadian infants received MenACWY at 2, 4, and 6 months or 2 and 4 months; at 12 months they received MenACWY, a plain tetravalent polysaccharide vaccine, or no vaccine. Main Outcome Measure  Percentage of infants with a human complement serum bactericidal activity (hSBA) titer 1:4 after a primary course of MenACWY and after a 12-month booster. Safety and reactogenicity of MenACWY were also assessed. Results  According to the prespecified per-protocol analysis, the percentages (95% CIs) of MenACWY 2-, 3-, and 4-month recipients with hSBA titers 1:4 after primary immunization were serogroup A, 93% (84%-98%); C, 96% (89%-99%); W-135, 97% (90%-100%); and Y, 94% (86%-98%). With a post hoc intention-to-treat analysis with imputed values for missing data, these values were unchanged for serogroups C and Y; for serogroup A, values were 92% (84%-97%), and for W-135, 97% (91%-99%). For the per-protocol analysis of MenACWY 2-, 4-, and 6-month recipients, the percentages (95% CIs) of responders were A, 81% (71%-89%); C, 98% (92%-100%); W-135, 99% (93%-100%); and Y, 98% (92%-100%). With the imputed value analysis, these values were A, 83% (74%-89%); C, 98% (93%-99%); W-135, 99% (94%-100%); and Y, 98% (92%-99%). At least 84% of MenACWY 2- and 4-month recipients achieved hSBA titers 1:4 for serogroups C, W-135, and Y after primary immunization, as did at least 60% for serogroup A (per-protocol and imputation analysis). At least 95% of primary and booster MenACWY recipients achieved hSBA titers 1:4 for serogroups C, W-135, and Y at 13 months, as did at least 84% for serogroup A (per-protocol and imputation analysis). During the primary immunization course, postimmunization pain on leg movement was observed in 2% of UK MenACWY 2- and 4-month recipients and 4% of MenC 2- and 4-month recipients; a temperature of 38°C or greater was observed in 4% and 2% in these groups, respectively. Conclusion  MenACWY is well tolerated and immunogenic in infancy. Trial Registration  clinicaltrials.gov Identifier: NCT00262002   相似文献   
89.
BACKGROUND: Growth hormone (GH) replacement in adult GH-deficient (GHD) patients is reported to have a long-term beneficial effect on muscle mass and function, these effects being greater in young males and in adult-onset compared with those with childhood-onset GHD. To date, more discordant data are reported on the degree of muscle impairment in untreated GHD patients, due to the large heterogeneity of this syndrome. METHODS: Muscle maximum total isotonic strength (ST), lower limb maximum power output (W), maximum aerobic capacity (VO(2)max) and body composition (by tetrapolar bio-impedentiometry) were evaluated in seven short-stature adults with childhood-onset GHD and in seven age-matched normal-stature controls with comparable lifestyle and daily physical activity. RESULTS: Significant differences were found in body composition between control subjects and GHD patients, who presented higher adiposity (mean BMI+/-SD: GHD, 27.8+/-5.8 kg/m(2); controls, 22.1+/-0.8 kg/m(2); p=0.047), larger fat mass (GHD, 21.8+/-10.7 kg; controls, 8.8+/-3.5 kg; p=0.008), and lower fat-free mass (GHD, 65.8+/-11.4 %; controls, 87.0+/-6.5 %; p=0.002). In absolute terms, GHD patients attained significantly lower values in ST (GHD, 2479+/-493 N; controls, 4578+/-1476 N; p=0.008), W (GHD, 1092+/-452 W; controls, 1910+/-781 W; p=0.035) and VO(2)max (GHD, 1.68+/-0.40 l/min; controls, 2.67+/-0.84 l/min; p=0.035) than those attained by controls. The differences were still evident when the results were normalized by unit body mass, whereas they disappeared when the parameters were expressed per unit fat-free mass, suggesting for these patients the presence of an intrinsic muscle function in the same range as that of control subjects. CONCLUSIONS: Middle-aged and short-stature adults with childhood-onset GHD, who received discontinuous pit-GH substitution therapy only during childhood and have uncorrected long-lasting GHD, still retain a normal intrinsic muscle capability in attaining isotonic strength, generating anaerobic power as well as accomplishing oxidative processes. Nonetheless, it is not known which age-dependent evolution in motor dysfunction could be expected in this subgroup of GHD patients, when ageing processes add up to hormonal deficiencies.  相似文献   
90.
Background Imiquimod use in the treatment of basal cell carcinoma (BCC) has proven to be successful in a large percentage of cases, inducing tumor regression; however, the exact cellular mechanism has not been fully clarified. Aim To measure the morphological changes in the tumor microenvironment and the markers of apoptosis in skin biopsies from patients with BCC before and after imiquimod treatment. Methods In this open label study, skin biopsies obtained from 11 patients with BCC were evaluated before and after imiquimod treatment for: (i) morphological changes in the tumor microenvironment, with specific emphasis on the immunophenotype of inflammatory cells around the tumor; and (ii) markers of apoptosis, including expression of death receptors. Results Imiquimod treatment induced a significant increase in the mononuclear inflammatory response. In the majority of cases, the cellular infiltrate was predominantly composed of CD3+/CD4+ T cells, suggesting that the effector response is mediated by CD3+/CD4+ lymphocytes, with a minor cytotoxic and natural killer (NK) component. An increase in the cytotoxic CD3+/CD8+ T‐cell population was also observed. Imiquimod treatment was associated with a marked increased in CD20+ B cells, and a less pronounced enhancement in cells of monocyte–macrophage origin (CD68+) surrounding, or within, the tumor. This finding indicates either that macrophages play a minor role in the imiquimod‐induced response, or the recruitment of these cells is related to time and dose. Imiquimod treatment decreased CD1A+ Langerhans cells in the epidermis and increased the number of CD1A+ dendritic cells within the tumor aggregates. Imiquimod reduced Bcl‐2 expression, but no difference was found in Bax, Fas/FasL, and p53 expression in BCC cells. Conclusions Our results support the hypothesis that imiquimod activity in the treatment of BCC is partly a result of a pro‐inflammatory action mediated by CD3+/CD4+ lymphoid cells and of a pro‐apoptotic activity associated with decreased Bcl‐2 expression.  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