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   28641篇
  免费   1773篇
  国内免费   201篇
耳鼻咽喉   320篇
儿科学   875篇
妇产科学   825篇
基础医学   2855篇
口腔科学   800篇
临床医学   2392篇
内科学   6234篇
皮肤病学   620篇
神经病学   1341篇
特种医学   1045篇
外国民族医学   9篇
外科学   5026篇
综合类   808篇
现状与发展   1篇
一般理论   23篇
预防医学   2052篇
眼科学   834篇
药学   2505篇
中国医学   189篇
肿瘤学   1861篇
  2023年   385篇
  2022年   1089篇
  2021年   1589篇
  2020年   856篇
  2019年   1124篇
  2018年   1410篇
  2017年   906篇
  2016年   927篇
  2015年   1009篇
  2014年   1245篇
  2013年   1561篇
  2012年   2102篇
  2011年   2174篇
  2010年   1122篇
  2009年   922篇
  2008年   1372篇
  2007年   1484篇
  2006年   1311篇
  2005年   1134篇
  2004年   1044篇
  2003年   890篇
  2002年   826篇
  2001年   387篇
  2000年   373篇
  1999年   350篇
  1998年   192篇
  1997年   135篇
  1996年   123篇
  1995年   128篇
  1994年   83篇
  1993年   69篇
  1992年   189篇
  1991年   187篇
  1990年   163篇
  1989年   144篇
  1988年   149篇
  1987年   135篇
  1986年   133篇
  1985年   122篇
  1984年   99篇
  1983年   114篇
  1982年   57篇
  1981年   59篇
  1980年   45篇
  1979年   100篇
  1978年   64篇
  1977年   65篇
  1976年   50篇
  1975年   58篇
  1974年   60篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
63.
BACKGROUND: The deliberate use of ketoconazole to reduce the need for cyclosporine (CsA) is not new, but it is particularly relevant because of the high cost of CsA. Many studies have documented this benefit in renal and cardiac transplants, but this co-administration has not been reported in patients with nephrotic syndrome. METHODS: This retrospective study included 207 nephrotic patients who were steroid resistant, dependent or frequent relapsers and received CsA therapy. Among these patients 153 received daily ketoconazole therapy in a dose of 50 mg with concomitant decrease of one-third of the CsA dose while 54 patients received CsA alone. The majority of our cases were children (179 were below 18 years) and male to female ratio was 1.7:1. RESULTS: The great majority of the study population received the drugs for 1-2 years. Patients who received CsA and ketoconazole were comparable with those who received CsA alone regarding age, sex, duration of renal disease, renal pathology, severity of nephrotic syndrome, renal function, hepatic function and steroid response. Co-administration of ketoconazole significantly reduced mean doses of CsA by 37% after 1 month and 47% at 1 year with overall net cost savings of 37%. Hepatic functions remained within the normal range in both groups. Additionally, co-administration of ketoconazole significantly improved the response to CsA therapy, successful steroid withdrawal and decreased the frequency of renal impairment. CONCLUSIONS: Co-administration of keto with CsA in idiopathic nephrotic patients significantly reduces CsA costs and may improve its response.  相似文献   
64.
Using immunohistochemical and biochemical techniques, the occurrence of endogenous opioid peptides and their receptors in normal rat bone and joint tissues was investigated. Opioid receptors were detected, quantified, and characterized in homogenates from capsule/synovium and periosteum using radioligand binding assays. Receptor binding of the nonselective opioid [3H]naloxone to tissue homogenates was stereospecific and saturable, showing similar characteristics to that of brain tissue, although with lower binding capacities. By immunohistochemistry, the neuronal occurrence of four different enkephalins was demonstrated in synovium, bone marrow, periosteum, and juxta-articular bone, whereas no neuronal dynorphin immunoreactivity was detected. Double-staining studies disclosed that enkephalins coexisted with substance P in primary afferent fibers. The applied techniques can be used to assess changes in the distribution of endogenous opioids and their receptors in joint tissues in conditions associated with pain and inflammation. The endogenous opioid system now demonstrated might be targeted and exploited therapeutically to obtain peripheral control of symptoms in joint disorders.  相似文献   
65.
Eighteen male patients undergoing elective surgical reconstruction of the abdominal aorta were divided into two groups. Patients in Group I (nine) were given dopamine intravenously, in a dose of 2 micrograms/kg/min, during the first half of the period of cross-clamping, whilst those in Group II received dopamine during the second half. Each patient acted as his own control and for each, three periods were examined, namely: pre-clamp, clamping with dopamine and clamping without dopamine. Dopamine infusion during aortic clamping caused a significant rise in sodium output (P less than 0.01), potassium output (P less than 0.05), creatinine clearance (P less than 0.05) and urine output (P less than 0.05). We conclude that dopamine infusion during aortic clamping helps to protect the kidney from any deleterious effect of clamping.  相似文献   
66.
We describe 100 consecutive patients with histologically proven gastric carcinoma who were admitted to various hospitals in Northern Pakistan. Twenty-six per cent of patients were under 40 years of age. In a majority of patients the tumour was of a morphological type associated with poor prognosis. In most cases the disease was already at an advanced stage at the time of diagnosis, and most patients died within one year.  相似文献   
67.
The routine chest radiographs of 178 psychiatric patients were reviewed. 67 patients had abnormalities found on their chest radiographs. 22 (32.8 pc) of these were significant abnormalities while 45 (67.2 pc) were non-significant. There was no significant abnormality detected on the chest radiographs of any patient in whom abnormality had not been suspected clinically. No significant abnormality was found in patients below the age of 40 years. This study suggests that chest radiography should be performed only on psychiatric patients who are above the age of 40 years and especially those who have clinical evidence of chest disease.  相似文献   
68.
There are significant variations among countries in the incidence of brain abscess. We report here 26 cases of brain abscess treated at the Neurosurgery Department of King Faisal University and Dammam Central Hospital Saudi Arabia over a six year period (1982–1988). This is 2.3% of total admissions to the two neurosurgery departments serving a population of approximately 1.2 million in the same period.Young males were most often affected (M/F ratio 3.3:1; 31% were less than 15 years old, 46% aged between 15–39 years, and 23% older than 40 years). Streptococcus was found to be the most common microorganism (38.4%). Mixed infection was seen in 15.3%, and sterile abscesses were found in 11.5% of the patients after aerobic and anaerobic cultures of the pus. Chronic otitis media and paranasal sinusitis predisposed the patients to abscess formation in 57.6% of the cases. The temporo-parietal area was the commonest site. Epilepsy was a complication in 30.7% of our patients, and the mortality rate was 15.3%.  相似文献   
69.
Modification of human thrombin: effect on thrombomodulin binding   总被引:1,自引:0,他引:1  
Thrombomodulin, an endothelial cell protein, binds thrombin with high affinity and alters thrombin from a procoagulant to an anticoagulant molecule. In this study, chemical and/or proteolytic modification of thrombin was carried out to identify the essential components required for its interaction with thrombomodulin. Modification of thrombin at the catalytic site serine and histidine residues, with Diisopropylfluorophosphate and Tosyl-L-lysine chloromethyl ketone, resulted in loss of clotting and amidolytic activity. Both Diisopropyl phosphoryl-thrombin and Tosyl-L-chloromethyl ketone-thrombin inhibited native-thrombin: thrombomodulin catalyzed protein C activation with Ki values of 5 nM and 6 nM respectively indicating no loss of affinity for thrombomodulin. Oxidation of tryptophan residues with N-bromosuccinimide or iodination of tyrosine residues of thrombin led to reduced clotting and amidolytic activity as well as a reduced ability to interact with thrombomodulin. Modification of arginine residues with Phenylglyoxal and 2,3,Butanedione led to loss of thrombomodulin binding affinity. Limited proteolysis of thrombin by trypsin yielded the derivative beta-thrombin which had also lost its ability to interact with thrombomodulin. Deglycosylation of thrombin did not alter its binding affinity for thrombomodulin. These results indicate that one or more tryptophan, arginine and tyrosine residues are essential for the recognition of thrombin by thrombomodulin whilst the carbohydrate side chain and the active site residues of the thrombin molecule are not involved in thrombomodulin binding.  相似文献   
70.
The antibacterial activity of the volatile oil of Nigella sativa seeds was studied against 37 isolates of Shigella dysenteriae 1, Shigella flexneri, Shigella sonnei and Shigella boydii and 10 strains of Vibrio cholerae and Escherichia coli. Most of the strains were clinically resistant to ampicillin, co-trimoxazole and tetracycline. All the strains tested showed promising sensitivity to the volatile oil. The minimum inhibitory concentration (MIC) of the volatile oil for Shigella, Vibrio and Escherichia strains tested was between 50–400 μg/mL.  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