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   44510篇
  免费   2670篇
  国内免费   111篇
耳鼻咽喉   673篇
儿科学   2033篇
妇产科学   1023篇
基础医学   5439篇
口腔科学   1923篇
临床医学   4063篇
内科学   9155篇
皮肤病学   1118篇
神经病学   3749篇
特种医学   1392篇
外国民族医学   2篇
外科学   6991篇
综合类   155篇
一般理论   17篇
预防医学   2788篇
眼科学   1294篇
药学   2911篇
中国医学   184篇
肿瘤学   2381篇
  2023年   344篇
  2022年   218篇
  2021年   815篇
  2020年   548篇
  2019年   865篇
  2018年   1358篇
  2017年   964篇
  2016年   1077篇
  2015年   1042篇
  2014年   1314篇
  2013年   2027篇
  2012年   3116篇
  2011年   3578篇
  2010年   1815篇
  2009年   1293篇
  2008年   3037篇
  2007年   3244篇
  2006年   3151篇
  2005年   3191篇
  2004年   3037篇
  2003年   2811篇
  2002年   2688篇
  2001年   899篇
  2000年   989篇
  1999年   641篇
  1998年   379篇
  1997年   310篇
  1996年   249篇
  1995年   217篇
  1994年   189篇
  1993年   172篇
  1992年   147篇
  1991年   120篇
  1990年   117篇
  1989年   111篇
  1988年   96篇
  1987年   81篇
  1986年   94篇
  1985年   61篇
  1984年   71篇
  1983年   69篇
  1982年   62篇
  1981年   51篇
  1980年   57篇
  1979年   69篇
  1978年   49篇
  1977年   51篇
  1974年   41篇
  1973年   43篇
  1972年   36篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
81.
The relaxant effects of electrical field stimulation (EFS) and exogenously applied acetylcholine (ACh) or acidified NaNO2 (a-NaNO2) were investigated in the isolated mouse corpus cavernosum precontracted with phenylephrine hydrochloride (PE). Tetrodotoxin (TTX) blocked the relaxant effects of EFS completely, whereas it had no effect on the responses to ACh or a-NaNO2. Guanethidine and indomethacin failed to affect the electrically or ACh-induced relaxations. Atropine completely blocked the effect of ACh; however, it caused a slight reduction in the relaxation evoked by EFS.N G- Nitro-l-arginine (l-NOARG) reduced the effects of EFS and ACh significantly, but it was ineffective on the relaxations induced by a-NaNO2. The inhibitory action ofl-NOARG was partly restored byl-arginine, but not byd-arginine. Methylene blue (MB) and hydroxocobalamin (HC) exhibited significant inhibition on the relaxations evoked by EFS, ACh and a-NaNO2. Hydroquinone (HQ) reduced relaxation due to a-NaNO2, but did not affect that of EFS and ACh. Our findings suggest that EFS-induced relaxations of mouse cavernosal tissue are mediated by a transmitter which probably resembles an organic nitrate.  相似文献   
82.
83.
Infertility may occur in patients with unilateral testicular torsion whose contralateral testis is intact. Depending on this observation, the physicians have begun to examine the contralateral testis. In the present prospective study we aimed to examine the histopathologic alterations occurring in the contralateral testicle with time. Sixty adult male albino rats were included in the programme, and following experimental torsion the histopathologic findings, especially those in the contralateral testis, were evaluated after 4–12 weeks. Long-term and high degree torsion of the testicle led to varying degrees of deterioration in the germinal epithelium and interstitial cells of the contralateral testicle. Histopathologic alterations were reversed in 12 weeks. Tubular diameter and testicular volume also decreased in accordance with the histopathologic alteration. In our opinion, orchiectomy following torsion of one testicle will limit potential histopathologic alterations in the contralateral testicle.  相似文献   
84.
85.
Hydatid cysts of central nervous system are rare and comprise only 2% to 3% of all hydatid cysts reported. Orbital localization is very uncommon and has been reported less than 1 % of all hydatid diseases. The primary treatment of hydatid disease is surgical. The most important complication of the surgical treatment is secondary hydatidosis due to spillage of the cyst contents. Because of the difficulties of the orbital localization, total extirpation of the cysts without rupture is almost impossible. Preventing spontaneous rupture of the cysts during surgery and postoperative antihelmintic treatment should be taken into consideration in these cases.This study includes four cases who underwent surgery for orbital hydatid cysts. Radiological characteristics, operative technique and postoperative medical therapy are discussed.  相似文献   
86.
Chlamydial infections and male infertility   总被引:3,自引:0,他引:3  
Chlamydial infections may be difficult to diagnose due to the silent symptoms and difficulty in culturing. An infectious process may impair fertility by adversely affecting sperm functions, resulting in testicular damage or causing obstruction of the genital tract. In our study, we tried to find Chlamydial antigen by using EIA (Enzyme Immune Assay) and to compare the Ag(+) and Ag(−) groups according to semen parameters. Except for semen volume, we found significant differences in density, morphology, motility and viability (intervolume p>0.05, interdensity p<0.01, intermorphology p<0.001, intermotility p<0.001 and interviability p<0.001).  相似文献   
87.
Esthesioneuroblastoma is an uncommon malignant neoplasm that arises from olfactory mucosa, often with intracranial extension.A case report of the youngest victim in the literature (2-year-old boy) is presented.  相似文献   
88.
89.
Objective: To determine which characteristics of older patients who use a hospital ED are associated with repeat visits during the 90 days following the index visit.
Methods: The study was conducted in the ED of a 400-bed university-affiliated acute care community hospital in Montreal. Patients aged ≥75 years who visited the ED between 08:00 and and 16:00 on a convenience sample of days over an 8-week period (July and August 1994) were assessed using a questionnaire, physical and cognitive status instruments, and a functional problem checklist. The hospital's administrative database was used to identify repeat visits during the 90 days following the ED visit. The representativeness of the sample was assessed by analyses of ED visits made by 4,466 persons aged ≥65 years during a 12-month period (September 1993 to August 1994) using the hospital's administrative database.
Results: 256 patients aged ≥75 years visited the ED during the study period and 167 were assessed. Of these, 54 (32%) were admitted to the hospital. Among the 113 patients released from the ED, 27 (24%) made repeat visits during the next 90 days. In univariate analyses, repeat visits were significantly associated with the number of functional problems, cognitive impairment, and previous ED visits. In multiple logistic regression, male gender, living alone, and number of functional problems were independent predictors of repeat visits. In the administrative data analyses, nighttime arrival to the ED for the index visit was significantly associated with repeat visits.
Conclusions: Self-reported risk factors can help to identify a group of elders likely to make repeated ED visits; the development of a screening instrument incorporating questions on these problems and implementation of appropriate interventions might improve these patients' quality of life and reduce the demand for further ED care in this age group.  相似文献   
90.
Efficient RT-PCR on platelet mRNA after long-term storage   总被引:1,自引:0,他引:1  
We have developed a procedure permitting RT-PCR from mRNA even after a long-term storage (1 year) of platelet samples in ethanol (EtOH-platelets) at −80°C. To validate our method, we have analysed the human platelet alloantigen system (HPA-1) which is coded by β3 mRNA. We have also demonstrated the efficiency of amplification of part of the coding region for (i) αIIb subunit mRNA, (ii) αv subunit mRNA, and (iii) the seven transmembrane domain thrombin receptor mRNA.  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