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   35910篇
  免费   2786篇
  国内免费   370篇
耳鼻咽喉   398篇
儿科学   976篇
妇产科学   960篇
基础医学   4572篇
口腔科学   602篇
临床医学   3742篇
内科学   7670篇
皮肤病学   839篇
神经病学   2418篇
特种医学   1214篇
外科学   4885篇
综合类   1184篇
一般理论   32篇
预防医学   1979篇
眼科学   1587篇
药学   2724篇
中国医学   308篇
肿瘤学   2976篇
  2023年   268篇
  2022年   517篇
  2021年   960篇
  2020年   618篇
  2019年   783篇
  2018年   1002篇
  2017年   766篇
  2016年   870篇
  2015年   1047篇
  2014年   1377篇
  2013年   1649篇
  2012年   2345篇
  2011年   2458篇
  2010年   1417篇
  2009年   1248篇
  2008年   1921篇
  2007年   2006篇
  2006年   1999篇
  2005年   1930篇
  2004年   1708篇
  2003年   1587篇
  2002年   1416篇
  2001年   1124篇
  2000年   1053篇
  1999年   910篇
  1998年   368篇
  1997年   274篇
  1996年   257篇
  1995年   203篇
  1994年   201篇
  1993年   198篇
  1992年   453篇
  1991年   444篇
  1990年   421篇
  1989年   401篇
  1988年   355篇
  1987年   372篇
  1986年   330篇
  1985年   282篇
  1984年   208篇
  1983年   151篇
  1982年   99篇
  1981年   87篇
  1980年   92篇
  1979年   138篇
  1978年   91篇
  1977年   74篇
  1976年   78篇
  1975年   80篇
  1972年   69篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
K. L. Chan 《Hernia》2007,11(1):37-40
Background Open repair of recurrent paediatric inguinal hernias (IH) is difficult and there is definite risk of damaging the vas deferens and testicular vessels during dissection of the previous open herniotomy field. Laparoscopic repair (LR) has the benefit of avoiding the previous operative site. Method Records of patients with recurrent IH that had LR after open repair were reviewed and evaluated retrospectively. The results were compared with data from cases in which the LR method was used in the initial IH repair. Results From September 2002 to October 2005, four boys and one girl (mean age 58.8 months) were treated in our institution for recurrent IH after open repair. Operative time, success rate and complications did not show any statistically significant difference when compared with our previous prospectively collected data for primary repairs. Conclusion Laparoscopic repair is the preferred operation for recurrent childhood IH after open repair.  相似文献   
53.
Trisomy 8 and, less commonly tetrasomy 8, are karyotypic aberrations found in myeloid malignancies. We describe a unique case of acute myeloid leukemia with partial pentasomy 8 resulting from duplication of isochromosome 8q, and discuss its possible roles in leukemogenesis.  相似文献   
54.
Phase I trial of piroxicam in 62 dogs bearing naturally occurring tumors   总被引:3,自引:0,他引:3  
Summary Piroxicam, a nonsteroidal antiinflammatory drug, was given to 62 dogs bearing naturally occurring tumors in a phase I clinical trial. Dose escalation was performed, with oral doses ranging from 0.5 mg/kg every 48 h (q48h) to 1.5 mg/kg q48h being tested. Dose-limiting gastromestinal irritation/ulceration occurred in all four animals that received 1.5 mg/kg q48h. The maximum tolerated dose was 1 mg/kg q48h. Subclinical renal papillary necrosis occurred in two dogs (initial dosages, 1 and 1.5 mg/kg q48h, respectively). Following dose escalation, an additional group of dogs was treated with 0.3 mg/kg piroxicam q24h per os, the accepted canine dosage prior to this trial. Inclusion of this treatment group enabled evaluation of the toxicity of and tumor response to a daily dosage regimen. No complete remissions occurred in this trial. Partial remission was documented in three of ten dogs exhibiting transitional-cell carcinoma, in three of five animals bearing squamous-cell carcinoma, in one of three dogs displaying mammary adenocarcinoma, and in the one dog that exhibited a transmissible venereal tumor. The results of this study support the additional evaluation of piroxicam in a phase II clinical trial in dogs bearing naturally occurring tumors.This investigation was supported by Pfizer Inc.  相似文献   
55.
Background: The lack of depth perception and spatial orientation in video vision are the drawbacks of laparoscopic surgery. The advent of a three-dimensional camera system enables surgeons to regain binocular vision and may be advantageous in complex laparoscopic procedures. Methods: We prospectively studied two groups of surgeons (with and without experiences in laparoscopic surgery) who performed a designated standardized laparoscopic task using a two-dimensional camera system (Olympus OTV-S4) vs a three-dimensional camera system (Baxter-V. Mueller VS7700) and compared their time performances. Results: The results suggested that only experience in laparoscopic surgery had significant effect on individual's performance. We could not demonstrate any superiority of the 3D system over the 2D system. However, two-thirds of the surgeons commented that the depth perception did improve. Conclusions: With further refinement of the technology, the 3D system may improve its potential in laparoscopic surgery.  相似文献   
56.
p-Aminobenzoic acid (PABA), p-acetamidobenzoic acid (PADB) and p-aminohippuric acid (PAH) have been separated and determined by a reversed phase, isocratic high performance liquid chromatographic (HPLC) procedure simultaneously. The mobile phase, at 1.5 ml min-1, used was 10 mM sodium hydrogen phosphate buffer, pH 3.5, containing 40% methanol. The eluent was detected at 270 nm. Linear relationship was obtained from 0 to 2.0 micrograms ml-1 of each compound with the corresponding peak-height ratio using p-methylamino-benzoic acid (PMAB) as the internal standard. Urine samples were obtained from healthy Chinese volunteers after oral dosing of 200 mg PABA which was used as a model substance for metabolic investigation of N-acetylation and other conjugation reactions. The 24 hour urinary recovery, from 43 healthy subjects, of PABA, PABA-COOH conjugates, PADB and PADB-COOH conjugates were (mean +/- S.D.) 2.9 +/- 1.5%, 5.2 +/- 3.3%, 13.9 +/- 4.0% and 42.9 +/- 9.8% of the ingested dose respectively. These accounted for 64.9 +/- 12.0% of total dose ingested in 24 hour. In contrast to previously reported findings on one Caucasian subject, no PAH was identified in the urine, and N-acetylation was the major route of metabolism of PABA apart from conjugation at the -COOH group in this group of Chinese volunteers. It is proposed that PABA metabolism may be a useful probe to study ethnic and geographic variation in N-acetylation.  相似文献   
57.
Our initial characterization of a herpes simplex virus type 1, temperature sensitive host shutoff mutant, called ts1-8, revealed that it has a low plaquing efficiency and exhibits a defect in the shutoff of host polypeptide synthesis and host DNA replication at the nonpermissive temperature of 39.5 degrees C. Using intratypic marker rescue experiments the ts plaquing mutation was mapped to a 557 bp region. Sequence analysis and complementation studies revealed that the low plaquing efficiency phenotype is due to a mutation in the glycoprotein B gene converting Pro-357 to Ser. This novel tsgB mutation is located in a conserved region of gB and it is distinct from the delayed host shutoff mutation (dhs).  相似文献   
58.
A chromium electroplating worker, suffering from epistaxis during work, was found to have nasal septum perforation. To determine the etiology and prevalence of nasal septum lesions, we conducted a survey of seven chromium electroplating factories and examined 79 workers. Forty workers from three aluminum electroplating factories were also enrolled as the reference group. Subjects were thoroughly examined by an otolaryngologist and each of them provided a blood and urine sample. A questionnaire interview regarding symptoms of the upper respiratory tract, past medical history, life style, and work history was also conducted. Air chromium concentrations were measured by taking area samples for 4–6 hours. Based on field observation and chromium measurements, we divided chromium electroplating into three different exposure zones: workers directly dealing with electroplating tanks (n = 31), other process workers (n = 29), and office workers and drivers (n = 19). Among the 79 chromium electroplating workers, there were 16 cases of nasal septum perforation, and 42 with either scar formation or ulceration; 10 chromium electroplating workers developed skin ulcers after performing chrome plating. No workers from aluminum electroplating factories had any nasal septum or skin abnormalities. There was a consistent trend between the degree of chromium exposure and the signs and symptoms related to the nose, throat, and skin. Immediate improvement of occupational hygiene is warranted.  相似文献   
59.
The effect of the proton pump inhibitor omeprazole on the anticoagulation and the pharmacokinetics of warfarin enantiomers was studied in rats. Omeprazole given intraperitoneally in a daily dose of 0.67 mg/kg over 8 days had no significant effect on the absorption, distribution and the total serum clearance values of the S- and R-enantiomers of warfarin. Omeprazole did not affect the pre-treatment baseline blood coagulation and the in vitro rat serum protein binding of warfarin enantiomers. In vitro study with rat liver microsomes showed that omeprazole had an inhibitory effect on the hydroxylation of warfarin enantiomers. Results obtained from in vivo urinary excretion study revealed that omeprazole inhibited the formation clearance of both S- and R-form oxidative metabolites, but increased that of the overall reductive metabolites, and the renal clearance of S- and R-enantiomers, of warfarin. As a consequence, the total serum clearance values for warfarin enantiomers remained unchanged and the hypoprothrombinaemic response produced by warfarin was not affected.  相似文献   
60.
OBJECTIVES: The impact of command hallucinations on patients and the determinants of patients' compliance with them are still poorly understood. The extant literature is also divided on their association with violence. This study aimed to establish the prevalence of command hallucinations and to identify the factors that affect compliance with the commands, together with patients' coping methods. METHODS: We recruited 50 consecutive male and 50 consecutive female schizophrenia inpatients who reported hearing voices in the 6 months prior to admission. We interviewed these patients, using a semistructured questionnaire. We collected information on the contents of their auditory hallucinations and their coping methods. RESULTS: Of the patients, 53 (53%) reported command hallucinations. Of these 53 patients, 58% were women and 48% were men; 62% reported complying with the commands. They were also more likely to comply with nonviolent commands. A history of self-harm predicted compliance. Those patients who did not comply with the commands adopted various methods of coping, of which praying was the most common. CONCLUSION: Command hallucinations are common in patients with schizophrenia. Patients with a history of self-harm need closer monitoring because they may be more likely to comply with these hallucinations. Assessment should also include the patient's own coping strategies, which can be incorporated into the treatment.  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