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   35638篇
  免费   2776篇
  国内免费   352篇
耳鼻咽喉   391篇
儿科学   965篇
妇产科学   955篇
基础医学   4555篇
口腔科学   582篇
临床医学   3710篇
内科学   7607篇
皮肤病学   831篇
神经病学   2413篇
特种医学   1166篇
外科学   4873篇
综合类   1172篇
一般理论   32篇
预防医学   1962篇
眼科学   1583篇
药学   2708篇
中国医学   307篇
肿瘤学   2954篇
  2023年   265篇
  2022年   511篇
  2021年   959篇
  2020年   615篇
  2019年   781篇
  2018年   997篇
  2017年   762篇
  2016年   868篇
  2015年   1043篇
  2014年   1373篇
  2013年   1637篇
  2012年   2342篇
  2011年   2454篇
  2010年   1402篇
  2009年   1234篇
  2008年   1912篇
  2007年   1990篇
  2006年   1992篇
  2005年   1925篇
  2004年   1700篇
  2003年   1582篇
  2002年   1414篇
  2001年   1119篇
  2000年   1051篇
  1999年   904篇
  1998年   355篇
  1997年   262篇
  1996年   241篇
  1995年   194篇
  1994年   188篇
  1993年   187篇
  1992年   452篇
  1991年   439篇
  1990年   419篇
  1989年   394篇
  1988年   346篇
  1987年   366篇
  1986年   320篇
  1985年   272篇
  1984年   203篇
  1983年   146篇
  1982年   94篇
  1981年   85篇
  1980年   89篇
  1979年   138篇
  1978年   89篇
  1977年   72篇
  1976年   76篇
  1975年   77篇
  1972年   69篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
The suicide rate has been paralleled by an upward trend of unemployment in Hong Kong since 1997. This study aims to explore the unknown suicide-related factors among the unemployed. This information is useful in developing culturally specific suicide prevention initiatives related to unemployment. Seventy-six suicide deceased and 15 life subjects who were unemployed were selected from a previous psychological autopsy study. Logistic regression models were employed to estimate the relative suicide risks among the unemployed people. Among the unemployed, the suicide deceased were more likely to be male, had suffered from psychiatric illness, and had attempted suicide before. They also had acquired less competent social problem solving skills. Comparison with a small control group creates a generalizability problem. Suicide prevention for the unemployed could be done through mental health awareness programs; problem-solving skills training for attempters and males; and vocational training and job opportunities for discharged psychiatric patients and rehabilitees.  相似文献   
92.
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   
93.
94.
为了比较中国内地城市和香港青少年儿童的心肺耐力和肌肉素质,对两地的青少年儿童体质调查数据进行了比较研究。结果发现:内地各年龄组男女生的心肺耐力均优于香港同龄者;香港青少年儿童的肌肉素质除立定跳远外,其他项目的成绩均弱于内地青少年儿童。提示:随着生活水平的提高,应重视青少年儿童对体育活动的参与。  相似文献   
95.
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   
96.
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   
97.
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   
98.
A 46-year-old man presented with shock and adult respiratory distress syndrome. Investigations revealed an adrenal mass that was diagnosed, by fine-needle aspiration biopsy, as pheochromocytoma. Because biopsy is contraindicated in patients with pheochromocytoma, this confusing presentation underscores the value of excluding this diagnosis by biochemical means before performing fine-needle aspiration of adrenal tumours.  相似文献   
99.
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   
100.
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   
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