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   7406篇
  免费   799篇
  国内免费   28篇
耳鼻咽喉   109篇
儿科学   158篇
妇产科学   293篇
基础医学   975篇
口腔科学   146篇
临床医学   906篇
内科学   1700篇
皮肤病学   116篇
神经病学   623篇
特种医学   199篇
外科学   844篇
综合类   103篇
一般理论   13篇
预防医学   644篇
眼科学   112篇
药学   698篇
中国医学   45篇
肿瘤学   549篇
  2023年   44篇
  2022年   92篇
  2021年   235篇
  2020年   176篇
  2019年   256篇
  2018年   253篇
  2017年   214篇
  2016年   271篇
  2015年   259篇
  2014年   293篇
  2013年   455篇
  2012年   541篇
  2011年   567篇
  2010年   378篇
  2009年   313篇
  2008年   471篇
  2007年   467篇
  2006年   443篇
  2005年   410篇
  2004年   337篇
  2003年   304篇
  2002年   295篇
  2001年   132篇
  2000年   122篇
  1999年   107篇
  1998年   57篇
  1997年   39篇
  1996年   32篇
  1995年   29篇
  1994年   16篇
  1993年   34篇
  1992年   64篇
  1991年   47篇
  1990年   45篇
  1989年   46篇
  1988年   44篇
  1987年   33篇
  1986年   20篇
  1985年   32篇
  1984年   26篇
  1983年   20篇
  1980年   15篇
  1979年   20篇
  1978年   17篇
  1977年   14篇
  1975年   17篇
  1974年   13篇
  1973年   13篇
  1972年   13篇
  1971年   13篇
排序方式: 共有8233条查询结果,搜索用时 218 毫秒
11.
Objective: Two major changes have occurred in inguinal hernia repair during the last two decades: (i) the use of tension‐free mesh repair; and (ii) the application of laparoscopic technique for repair. The aims of the present study were to study: (i) how inguinal hernia repair was carried out; and (ii) the outcome of inguinal hernia repair in Hospital Authority (HA) hospitals. Methodology: This was a retrospective analysis on 8311 elective inguinal hernia repairs performed in 16 HA hospitals from January 2001 to December 2003. The mean age was 63.9 ± 14.2 years, and the male to female ratio was 22.0 : 1.0. Among these, 869 (10.5%) repairs were performed with the laparoscopic approach and 7442 (89.5%) repairs with the open approach. The proportion of laparoscopic hernia repair increased from 8.7% to 12.6%. Results: For open repair, 39% of cases were carried out with regional anaesthesia, 32% with general anaesthesia and 29% with local anaesthesia (LA). Furthermore, mesh repair was used in 88% of the patients. For laparosocpic repair, 98.4% of cases were carried out under general anaesthesia, and all patients had mesh repair using the totally extraperitoneal approach. A significantly higher proportion of bilateral repair and recurrent hernia repair was performed with the laparoscopic approach (P = 0.000). For primary unilateral repair, there was no significant difference in the postoperative length of stay (LOS) and the total LOS between the laparoscopic and the open surgery groups. No difference in LOS was found in recurrent hernia repair between the two groups. With respect to bilateral repair, both the preoperative LOS (P = 0.036) and total LOS (P = 0.039) were shorter in the laparoscopic group. Furthermore, a significantly higher proportion of day‐surgery patients was observed in the laparoscopic group than the open surgery group (21.3%vs 16.9%, P = 0.001). Nevertheless, when only the results of 2003 were analyzed, the postoperative LOS (P = 0.000) and total LOS (P = 0.000) were significantly shorter in the laparoscopic group than the open surgery group. The LOS parameters were significantly shorter in the open surgery LA subgroup compared with the non‐LA subgroup (P = 0.000), and they were not different from those in the laparoscopic group. Conclusions: The open mesh repair is the predominant approach for inguinal hernia repair in HA hospitals. The originally described local anaesthetic approach was under utilized, although it resulted in good outcome. The use of laparoscopic hernia repair is increasing and a learning curve was recently observed with improved outcome.  相似文献   
12.
A cohort study of tobacco use,diet, occupation,and lung cancer mortality   总被引:1,自引:0,他引:1  
In 1966, a cohort of White males aged 35 or over, who were policy-holders with the Lutheran Brotherhood Insurance Society (United States), completed a mail questionnaire on tobacco use, diet, and demographic characteristics. During the 20 years of follow-up, 219 lung cancer deaths occurred. Besides the strong relationship with cigarette smoking, we observed an effect on lung cancer risk among current users of cigars or pipes who were nonsmokers of cigarettes (relative risk [RR]=3.5, 95 percent confidence interval[CI]=1.0–12.6) or who were past/occasional users of cigarettes (RR=2.7, CI=1.4–5.3). In addition, elevated risks (from 1.5 to 2.6) of lung cancer were found among craftsmen and laborers, with the highest risks among subjects who worked in the mining or manufacturing industry. No association between current (as of 1966) use of beer or hard liquor and lung cancer was observed, although past users were at elevated risk. An inverse association between lung cancer and intake of fruits was observed, and risks of lung cancer were lower among persons in the highest dietary intake quintiles of vitamins A and C. Except for oranges, however, none of the inverse associations with fruits or dietary nutrients had statistically significant trends. The findings from this cohort study add to the evidence of an adverse effect of cigar/pipe smoking and possibly protective effect of dietary factors on lung cancer risk.  相似文献   
13.
The aqueous humor concentration of phenylephrine and its corresponding mydriatic response were measured over time in New Zealand albino rabbit eyes following a 10-µl topical instillation of a phenylephrine HC1 viscous solution (10%) or a phenylephrine oxazolidine (prodrug) suspension in sesame oil (1 and 10%). The bioavailability of a 1% prodrug suspension in the rabbit eye (AUC of aqueous humor concentration vs time) was 30% lower than that of a 10% phenylephrine solution (P < 0.1) with the exception that the peak time occurred 34 min earlier with the prodrug. A 10% prodrug suspension increased the aqueous humor bioavailability approximately eightfold but improved the mydriatic activity (AUC of mydriasis vs time) only fourfold. The pharmacokinetic parameters, apparent absorption, and elimination rate constants, of phenylephrine and the prodrug were determined from aqueous humor concentration–time and mydriasis–time profiles. The study showed that the kinetic parameters of phenylephrine estimated from its mydriasis profile do not accurately reflect the kinetics of drug distribution in the iris. These parameters also varied with the instillation of phenylephrine solution or prodrug suspensions. A mydriatic tolerance of the pupil response was apparent after the topical instillation of phenylephrine solution. The mydriatic tolerance may be due to the decrease in receptor number in the iris dilator muscle.  相似文献   
14.
As an ongoing effort to elucidate the mechanisms involved in the calcium-dependent fertility regulation process, the viscoelastic properties of the mucus obtained from lamb cervix and human semen, as well as their water and total protein contents after exposure to EDTA, a chelating agent, or Nonoxynol-9 (N-9), a spermicidal agent, were examined. The viscosity was measured using a Cone Plate Digital Viscometer, while the water and total protein contents were determined by the lyophilization process and the Lowry method, respectively. The significant changes in the rheological properties of mucus, such as its viscosity and the water content, upon exposure to EDTA were demonstrated. The viscosity of cervical mucus and human semen were significantly increased by EDTA treatment (as compared to the controls): lamb cervical mucus (2.9 ± 0.3 vs. 2.2 ± 0.3 cps) and human semen (5.0 ± 0.3 vs. 4.3 ± 0.3 cps), respectively. The hydration rate was decreased by EDTA treatment as compared with the control (93.6 ± 0.7 vs. 96.8 ± 0.8%). Among tested samples, the reduction in the percentage of sperm penetration through the cervical mucus was the highest in the mucus containing EDTA, which had the lowest water content (93.6 ± 0.7%), indicating that there is a positive relationship between the hydration rate of the cervical mucus and its ability to permit the penetration of spermatozoa. This result indicates that spermicidal activity exerted by high concentrations of EDTA is in part due to its effect on the rheological properties of cervical mucus or semen.  相似文献   
15.
16.
17.
OBJECTIVE: To assess the efficacy and safety of aripiprazole for psychosis associated with Alzheimer dementia (AD). METHODS: In this double-blind, multicenter study, 487 institutionalized patients with psychosis associated with AD were randomized to placebo or aripiprazole, 2, 5 or 10 mg/day. Primary efficacy assessment was the mean change from baseline to week 10 on the Neuropsychiatric Inventory-Nursing Home (NPI-NH) version Psychosis Subscale score. Secondary measures included NPI-NH Total, Clinical Global Impression-Severity of Illness (CGI-S), Brief Psychiatric Rating Scale (BPRS) Core and Total, and the Cohen-Mansfield Agitation Inventory (CMAI) scores. RESULTS: Aripiprazole 10 mg/day showed significantly greater improvements (mean change [2 x SD]) than placebo on the NPI-NH Psychosis Subscale (-6.87 [8.6] versus -5.13 [10.0]; F = 6.29, df = 1, 422, p = 0.013 by analysis of covariance [ANCOVA]); CGI-S (-0.72 [1.8] versus -0.46 [1.6]; F = 4.68, df = 1, 419, p = 0.031 [ANCOVA]); BPRS Total (-7.12 [18.4] versus -4.17 [21.6]; F = 4.72, df = 1, 399, p = 0.030 [ANCOVA]); BPRS Core (-3.07 [6.9] versus -1.74 [7.8]; F = 7.30, df = 1, 407, p = 0.007 [ANCOVA]); CMAI (-10.96 [22.6] versus -6.64 [28.6]; F = 5.23, df = 1, 410, p = 0.023 [ANCOVA]), and NPI-NH Psychosis response rate (65 versus 50%; chi(2) = 5.52, df = 1, p = 0.019 [CMH]). Aripiprazole 5 mg/day showed significant improvements versus placebo on BPRS and CMAI scores. Aripiprazole 2 mg/day was not efficacious. Cerebrovascular adverse events were reported: aripiprazole 2 mg/day, N = 1; 5 mg/day, N = 2; 10 mg/day, N = 4; placebo, N = 0. No deaths in any group (aripiprazole 2 mg/day, 3%; 5 mg/day, 2%; 10 mg/day, 7%; placebo, 3%) were considered to be treatment-related. CONCLUSION: Aripiprazole 10 mg/day was efficacious and safe for psychosis associated with AD, significantly improving psychotic symptoms, agitation, and clinical global impression. However, clinicians should be aware of the safety considerations of atypical antipsychotic uses in this population.  相似文献   
18.
BACKGROUND AND PURPOSE: Odontoma is the most common odontogenic tumor. It includes 2 types, the compound and complex odontomas. There has not been a series study of the clinical and histologic features of odontomas from Taiwan. This study evaluated the clinicopathologic features of odontoma in Taiwanese. METHODS: Cases of odontoma treated from 1998 to 2002 identified from medical records were included. The microscopic features, radiographic features, and clinical history of the patients were reviewed and analyzed. RESULTS: A total of 81 odontomas in 81 patients (36 males and 45 females) were included. There were 62 compound and 19 complex odontomas. The mean age of the patients was 18 years with the majority of odontomas occurring in the first (32%) and second decade (38%) of life. Odontomas had a marked predilection for the maxilla (70%) and for the anterior region of the jaw (83%), particularly for the anterior maxilla (62%). Sixty four (79%) of the 81 odontomas were associated with 80 impacted teeth, including 71 permanent teeth, 2 deciduous teeth, and 7 supernumerary teeth. Of the 71 impacted permanent teeth, the maxillary central incisor (27%) was most commonly affected, followed by the maxillary canine (26%) and mandibular canine (24%). Histologic examination revealed enamel matrix in 90%, dentin in 100%, cementum in 88%, pulp tissue in 96%, fibrous capsule in 93%, ghost cells in 83%, reduced enamel epithelium in 86%, and nests of odontogenic epithelium in 58% of odontomas. Dentigerous cyst was associated with 9% of odontomas. CONCLUSIONS: In this series, odontomas occurred most often in the first and second decade of life. Although complex odontomas are usually found in the posterior jaw, in this Taiwanese series they were most commonly found in the anterior maxilla. Odontoma is frequently associated with an impacted tooth and occasionally with a dentigerous cyst. No recurrence of odontomas was found after surgical excision with follow-up of 1 to 15 years.  相似文献   
19.
20.
The undecapeptide, substance P, is known to be synthesized in cell bodies of dorsal root ganglia. This neuropeptide is also known to modulate sensory, nociceptive transmission postsynaptically on dorsal horn interneurons. In the animal model used in the current study, experimental mechanical stimulation of dorsal root ganglia and nerve roots increased the amounts of substance P, as well as substance P immunoreactivity in cell bodies of the dorsal root ganglia and in the substantia gelatinosa of the spinal dorsal horn that the cell bodies innervated. These results were determined by using both immunohistochemistry and radioimmunoassay. This study suggests that substance P may modulate nociception when lumbar nerve roots are stimulated mechanically.  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