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   43106篇
  免费   2092篇
  国内免费   282篇
耳鼻咽喉   274篇
儿科学   889篇
妇产科学   432篇
基础医学   5171篇
口腔科学   958篇
临床医学   2739篇
内科学   11262篇
皮肤病学   720篇
神经病学   3109篇
特种医学   1961篇
外科学   7648篇
综合类   184篇
一般理论   1篇
预防医学   1290篇
眼科学   832篇
药学   2921篇
中国医学   61篇
肿瘤学   5028篇
  2023年   256篇
  2022年   519篇
  2021年   903篇
  2020年   484篇
  2019年   715篇
  2018年   889篇
  2017年   689篇
  2016年   897篇
  2015年   909篇
  2014年   1209篇
  2013年   1475篇
  2012年   2352篇
  2011年   2651篇
  2010年   1486篇
  2009年   1254篇
  2008年   2235篇
  2007年   2530篇
  2006年   2541篇
  2005年   2489篇
  2004年   2431篇
  2003年   2266篇
  2002年   2255篇
  2001年   1121篇
  2000年   1072篇
  1999年   992篇
  1998年   596篇
  1997年   470篇
  1996年   476篇
  1995年   336篇
  1994年   332篇
  1993年   285篇
  1992年   637篇
  1991年   589篇
  1990年   562篇
  1989年   535篇
  1988年   471篇
  1987年   439篇
  1986年   441篇
  1985年   421篇
  1984年   268篇
  1983年   209篇
  1982年   124篇
  1981年   111篇
  1979年   188篇
  1978年   124篇
  1977年   116篇
  1975年   97篇
  1973年   103篇
  1972年   98篇
  1970年   109篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
Primary extranodal malignant lymphoma frequently occurs in the gastrointestinal tract; however, it is rarely encountered in the rectum. We report herein the case of an 85-year-old man who underwent abdominoperineal resection for primary malignant lymphoma of the rectum, and 1 year later, developed hematemesis caused by gastric metastasis. To our knowledge this is the first case report of such distant metastasis developing from malignant lymphoma of the rectum.  相似文献   
102.
In order to evaluate the quality of life (QOL) in hypertensive outpatients, we selected 78 patients with hypertension of various degrees of severity (WHO Classification I: 29 cases, II: 15, III: 34), 59 not ill healthy persons (N1) and 22 normotensive outpatients (N2) aged at 50 years and over, using the self-completed questionnaire (QUIK) which we developed. QUIK covers four domains including physical functioning (20 questions), emotional adjustment (10), interpersonal relationships (10) and attitudes toward life (10) totaling 50 questions. In this study the internal consistency of QUIK was alpha = 0.95 by the Kuder-Richardson formula 20 and it's repeatability was r = 0.89 by the Spearman-Brown formula. The QOL in hypertensive outpatients was definitely worse in terms of total score (N1 5.1 +/- 4.4 vs WHO II 9.3 +/- 7.2 and III 12.1 +/- 5.6, p < 0.05), for physical functioning (N1 2.5 +/- 2.1 vs WHO I 3.7 +/- 2.8, II 4.7 +/- 3.8, III 5.4 +/- 2.8 p < 0.05), for emotional adjustment (N1 1.2 +/- 1.4 vs WHO III 2.3 +/- 1.7, p < 0.01), for interpersonal relationships (N1 0.8 +/- 1.3 vs WHO III 1.6 +/- 1.5, p < 0.01) and for attitudes toward life (N1 0.7 +/- 1.2 vs WHO III 2.7 +/- 2.0 p < 0.01). The total QUIK score increased according to the severity of symptoms (WHO I 5.8 +/- 4.4, WHO II 9.3 +/- 7.2 and WHO III 12.1 +/- 5.6), respectively. The total score of WHO I was significantly lower compared with that of WHO III (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
103.
The effects of 12 essential oils, popularly used as antifungal treatments in aromatherapy, on growth of Candida albicans were investigated. Mycelial growth of C. albicans, which is known to give the fungus the capacity to invade mucosal tissues, was inhibited in the medium containing 100 micro g/ml of the oils: lemongrass (Cymbopogon citratus), thyme (Thymus vulgaris), patchouli (Pogostemon cablin) and cedarwood (Cedrus atlantica). Not only lemongrass oil but also citral, a major component of lemongrass oil (80%), in the range of 25 and 200 micro g/ml inhibited the mycelial growth but allowed yeast-form growth. More than 200 micro g/ml of citral clearly inhibited both mycelial and yeast-form growth of C. albicans. These results provide experimental evidence suggesting the potential value of lemongrass oil for the treatment of oral or vaginal candidiasis.  相似文献   
104.
105.
106.
To examine species differences in the distribution pattern of guanosine triphosphate (GTP)-binding protein (Go) within the vertebrate retina, paraffin-embedded retinae from a number of vertebrate species, including the goldfish, frog, turtle, chicken, monkey, and human, were immunohistochemically stained with affinity-purified antibody against the alpha-subunit of Go. Go-immunoreactive products were found to be located in the neuropil, but not in the cell bodies of neurons, in the retina of all these species. However, some species differences were observed. In the frog, monkey and human, the inner plexiform layer (IPL) was homogeneously stained with this antibody, but in the goldfish, turtle and chicken, the IPL was heterogeneously stained. In the frog, chicken, turtle and human, the outer plexiform layer (OPL) was densely stained with this antibody, but in the goldfish and monkey, the OPL was rather faintly immunoreactive to the antibody. In the goldfish, monkey and human, the outer nuclear layer (ONL) was not immunoreactive to the Go-antibody, whereas in the frog, turtle and chicken, the ONL was immunoreactive to it. The implications of these species differences in Go localization in the vertebrate retina are discussed.  相似文献   
107.
108.
Male Sprague-Dawley rats (230-280 g), either fasted for 15-24 hr or non-fasted prior to experiments, were used. Misoprostol (3-100 micrograms/kg, p.o.) dose-dependently inhibited the development of 150 mM HCl X aspirin (100 mg/kg)-, 150 mM HCl X 60% ethanol-, and aspirin (150 mg/kg)-induced gastric lesions. Misoprostol (30, 100 micrograms/kg, p.o.), given twice daily for 4 days, significantly inhibited prednisolone (50 mg/kg given once daily for 4 days)-induced gastric lesions. Misoprostol (30 or 2 X 300 micrograms/kg, p.o.) also significantly inhibited water-immersion stress (21 degrees C, 10 hr)-induced gastric lesions or mepirizole (200 mg/kg)-induced duodenal lesions, respectively. In contrast, misoprostol (30-300 micrograms/kg, p.o.) had no effects on indomethacin (25 mg/kg)- and mepirizole (200 mg/kg)-induced gastric lesions. Misoprostol (30 micrograms/kg, p.o.) had no effect on gastric secretion in pylorus-ligated preparations (4 hr), but it (100 or 300 micrograms/kg, p.o.) significantly increased the volume and pepsin output. Gastric motility, either normal or enhanced with indomethacin (25 mg/kg), was inhibited by misoprostol (30 or 300 micrograms/kg, p.o.). Misoprostol (30 micrograms/kg, i.d.) significantly stimulated duodenal HCO3- secretion. Mechanisms by which misoprostol inhibits various gastric lesions remain unknown. However, the stimulatory activity on duodenal HCO3- secretion appears to be involved in the preventive effect of misoprostol on the development of duodenal lesions. The effects of cimetidine and 16,16-dimethyl PGE2 were also studied and compared with those of misoprostol.  相似文献   
109.
A 36-year-old man was admitted to a hospital with complaints of fever, polyarthralgia and dyspnea. Erythema was observed on his face, extensor surface of the fingers and extremities, and a chest X-ray revealed massive bilateral pleural effusion. He had no sign of myopathy at this point. Pleural fluid was proved to be exudative and contained extremely high levels of hyaluronic acid. He was also complicated with interstitial pneumonitis and was given a pulse therapy with methyl prednisolone followed by daily administration of 55 mg prednisolone (PSL). Twenty days after the commencement of the therapy, pleural effusion decreased but muscle weakness gradually appeared, accompanied by elevation of myogenic enzymes. Myogenic changes on electromyogram, and irregularity of the muscle fibers with slight inflammatory cell infiltrates in a biopsy specimen were demonstrated. He was transferred to our hospital, and a diagnosis of dermatomyositis was made. Later, pleural effusion waxed and waned depending on the dosage of PSL, but no other causative disorder was demonstrated by extensive examinations. This case indicates that the pleuritis could be one of the vasculitic manifestations of dermatomyositis.  相似文献   
110.
Ethylnitrosourea (ENU) is a simple alkylating agent. It induces gene mutations in fetal primordial germ cells (PGCs), and a high incidence of congenital malformations is also found in the offspring of male mice treated with ENU at the embryonic stage. It is also reported that decreases in the fertility rate and weights of the testis and ovary were found in the offspring from dams treated with ENU. In this study, we analyzed the occurrence of apoptotic cell death and the expression of p53 protein which is thought to play an important role in the DNA damage-induced apoptosis after administration of ENU to pregnant rats on day 13 of gestation to obtain a clue for clarifying the toxic effect of ENU on PGCs. Apoptotic cells increased in PGCs in fetal gonads from 3 h after treatment. The number of apoptotic PGCs peaked at 6 h and gradually decreased towards 24 h after treatment. On the other hand, p53-positive PGCs increased from I h after treatment, prior to the induction of apoptosis. The number of p53-positive PGCs peaked at 3 h and returned to the control level at 24 h after treatment. These results suggest that ENU induces apoptosis in rat fetal PGCs immediately after its administration to dams and excess cell death by apoptosis may have a close relation to the later occurrence of decreases in the fertility rate and gonadal weight. Moreover, a possible involvement of p53 is suggested in the ENU-induced apoptosis in PGCs.  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