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   11560篇
  免费   733篇
  国内免费   75篇
耳鼻咽喉   178篇
儿科学   413篇
妇产科学   410篇
基础医学   1060篇
口腔科学   368篇
临床医学   984篇
内科学   2488篇
皮肤病学   198篇
神经病学   557篇
特种医学   407篇
外科学   2241篇
综合类   367篇
现状与发展   1篇
一般理论   12篇
预防医学   719篇
眼科学   258篇
药学   933篇
中国医学   76篇
肿瘤学   698篇
  2023年   120篇
  2022年   350篇
  2021年   551篇
  2020年   311篇
  2019年   388篇
  2018年   486篇
  2017年   284篇
  2016年   391篇
  2015年   387篇
  2014年   519篇
  2013年   668篇
  2012年   922篇
  2011年   879篇
  2010年   506篇
  2009年   386篇
  2008年   622篇
  2007年   675篇
  2006年   633篇
  2005年   546篇
  2004年   488篇
  2003年   406篇
  2002年   386篇
  2001年   127篇
  2000年   111篇
  1999年   102篇
  1998年   67篇
  1997年   55篇
  1996年   43篇
  1995年   35篇
  1994年   41篇
  1993年   28篇
  1992年   87篇
  1991年   53篇
  1990年   66篇
  1989年   59篇
  1988年   44篇
  1987年   47篇
  1986年   24篇
  1985年   41篇
  1984年   29篇
  1983年   37篇
  1982年   20篇
  1980年   19篇
  1979年   33篇
  1978年   20篇
  1977年   26篇
  1976年   18篇
  1974年   34篇
  1973年   32篇
  1972年   23篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
A cross-sectional bacteriological survey of cattle in West Malaysia revealed 14.4% (32/222) had leptospiral infection. Isolates were obtained from all except one herd with prevalence of infection in herds ranging from 0-44.8%. A small number of buffalo urine samples were examined and all of them were found to be negative. A leptospiral isolate obtained from a bovine kidney proved to be a new serovar of Leptospira interrogans and the name unipertama was assigned to it. Six other leptospiral serovars were isolated, namely canicola, australis, javanica, ballum, pomona and hardjo. All six serovars were isolated for the first time in cattle in Malaysia. Cattle in Malaysia appear to be the maintenance host for serovar hardjo. The presence of the other serovars in cattle was probably due to contact with the maintenance hosts, pigs for serovar pomona and rodents for the other three serovars. It appears that the epidemiology of leptospiral infection in cattle in Malaysia is similar to that reported overseas.  相似文献   
22.
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   
23.
The anthelmintic activity of aqueous extracts (0.25–50 mg/mL) from 14 plant species that represent seven families of the Sudanese flora was examined using the free living rhabditid nematode, Caenorhabditis elegans as a test organism. Extracts of Balanites aegyptiaca and Sesbania sesban were the most effective (LC50, 0.8 and 8.0 mg/mL, respectively). Extracts of Albizzia anthelmintica, Cymbopogen narvatus, Abrus precatorius, Rhyncosia minima, Striga hermonthica and Anogeissus leiocarpa (LC50, 9.5–84.6 mg/mL were less effective in this model test system. Extracts of six plant species, Albizzia malacophylla, Gardenia lutea, Physostigma mesoponticum, Salvadora persica, Xeromphis nilotica and Waltheria indica had no effect upon C. elegans survival.  相似文献   
24.
Metastasis (the spread of cancer from a primary tumor to secondary organs) is responsible for most cancer deaths. The ability to follow the fate of a population of tumor cells over time in an experimental animal would provide a powerful new way to monitor the metastatic process. Here we describe a magnetic resonance imaging (MRI) technique that permits the tracking of breast cancer cells in a mouse model of brain metastasis at the single-cell level. Cancer cells that were injected into the left ventricle of the mouse heart and then delivered to the brain were detectable on MR images. This allowed the visualization of the initial delivery and distribution of cells, as well as the growth of tumors from a subset of these cells within the whole intact brain volume. The ability to follow the metastatic process from the single-cell stage through metastatic growth, and to quantify and monitor the presence of solitary undivided cells will facilitate progress in understanding the mechanisms of brain metastasis and tumor dormancy, and the development of therapeutics to treat this disease.  相似文献   
25.
26.
To investigate HER-2/neu oncoprotein immunoreactivity, monoclonal antibody TA1 immunohistochemical examination of flash-frozen radical prostatectomy specimens was performed (n = 35). All prostatic specimens contained benign prostatic hyperplasia (BPH) and/or prostatic intraepithelial neoplasia (PIN), as well as prostatic carcinoma (CaP). HER-2/neu oncoprotein immunoreactivity in BPH tissues was not significantly different than that for the PIN basal cell layer (P = 0.10) or for the PIN luminal cells (P = 0.17). There was significantly more HER-2/neu oncoprotein immunoreactivity in BPH than in areas of CaP (P < 0.001). There was no significant difference in the amount of immunoreactivity present in PIN basal cells when compared to the PIN luminal cells (P = 0.49). Both the PIN basal cells and luminal cells stained for the HER-2/neu oncoprotein to a higher degree than cells in the CaP areas (P < 0.001 in both cases). HER-2/neu oncoprotein immunoreactivity is present at a significantly higher degree in BPH and PIN than in malignant prostatic epithelium.  相似文献   
27.
Human papillomavirus is associated with a variety of anogenital lesions, including genital warts, precancers and cancers. In male patients human papillomavirus has been identified in proliferative lesions ranging from penile and urethral warts to penile and prostatic cancers. We examined the association of human papillomavirus deoxyribonucleic acid (DNA) in 84 prostate tissue specimens. Specimens were selected from radical prostatectomy, transurethral resection or transrectal biopsy procedures. A total of 60 formalin-fixed, paraffin-embedded tissues (24 prostate cancer specimens, 16 benign prostatic hyperplasia specimens and 20 normal specimens) was examined by polymerase chain reaction and in situ hybridization. Also, 24 gelatin-embedded frozen prostate cancer specimens were examined for human papillomavirus DNA by polymerase chain reaction. Of the specimens 69 were deemed adequate for polymerase chain reaction analysis, whereas all 60 paraffin-embedded tissues were sufficient for in situ hybridization. Human papillomavirus DNA was detected in 2 normal tissues and 6 prostate cancers using polymerase chain reaction. None of the benign prostatic hyperplasia specimens was positive for human papillomavirus. Human papillomavirus typing results indicated that virus type 16 was present in each of the 8 positive specimens. Confirmation of the presence of human papillomavirus was obtained for 1 of the prostate cancers by nonisotopic in situ hybridization with biotinylated human papillomavirus genomic probes. The low prevalence of human papillomavirus in this study population does not strongly support an etiological role for the virus in prostate cancer.  相似文献   
28.
OBJECTIVE: The purpose of this study was to evaluate whether intracoronary shunt usage reduced the myocardial damage on the basis of the cardiac markers when compared with the shuntless anastomosis in off-pump coronary artery bypass grafting (OPCABG) surgery of isolated left anterior descending artery lesions. METHODS: Forty patients who had stable angina with isolated left anterior descending (LAD) coronary artery lesion undergoing OPCABG surgery were randomized into two groups. Shunt group consisted of 20 patients who had OPCABG using intracoronary shunt, whereas the shuntless group consisted of 20 patients who underwent OPCABG without using intracoronary shunt. Cardiac troponin I, CK, and CK-MB before and 24h after the surgery were assessed in the groups. RESULTS: There were no deaths in the study. The two groups were similar with respect to sex and age. Duration of LIMA-LAD anastomosis was significantly higher in the shunt group (p=0.01). There was no significant difference between the groups concerning the preoperative and postoperative CK and CK-MB levels. The preoperative troponin I levels of the groups were not different (p=0.238; NS), whereas postoperative levels of this marker was significantly higher in the shuntless group (p=0.003). CONCLUSION: Intracoronary shunt reduced the postoperative troponin I levels significantly, so it may be indicated in the patients who are thought to be susceptible to transient ischemia.  相似文献   
29.
Complications in a donor are a distressing but inevitable occurrence, since graft procurement is a major undertaking. Although the technique for procurement has some similarities to hepatic resection, a donor is very unlike a patient with malignancy. The risk factors identified in these patients cannot be extrapolated to donors. Donor hepatectomy carried out from June 1995 to March 2005 in Chang Gung Memorial Hospital, Kaohsiung Medical Center was reviewed with the aim of identifying risk factors for complications. There were 204 living donor liver transplants, with 205 donor hepatectomies, as 1 living donor liver transplantation was a dual graft. Ten donors (4.88%) suffered complications. There was no difference in terms of age, gender, body weight, operation, and parenchymal time between those who had complications and those who did not. There was also no difference in liver function tests between the 2 groups of donors, but the total bilirubin was significantly higher in donors with complications. The graft weight and remnant liver volume were also similar. The proportion of donors with fatty liver was the same between the 2 groups. The mean blood loss in donors with complications was 170 +/- 79 mL, and that for donors without complications was 95 +/- 77 mL. There was a statistically significant greater blood loss in donors with complications (P < 0.05). The number of segments removed in donors with complications was also higher compared to donors without complications (P < 0.03). Using multivariate analysis, intraoperative blood loss and the number of segments removed were found to be independent risk factors for donor complications. Intraoperative blood loss during graft procurement must be kept low to minimize complications in donors.  相似文献   
30.
BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited human kidney disease and is caused by germline mutations in PKD1 (85%) or PKD2 (15%). It has been estimated that around 1% of tubular cells give rise to cysts, and cell hyperproliferation has been noted to be a cardinal feature of cystic epithelium. Nevertheless, it is uncertain whether the increase in proliferative index observed is an early or late feature of the cystic ADPKD kidney. METHODS: Two Pkd2 mouse mutants (WS25 and WS183) have been recently generated as orthologous models of PKD2. To determine the effect of Pkd2 dosage on cell proliferation, cyst formation and renal fibrosis, we studied renal tissue from Pkd2(WS25/WS25) and Pkd2(+/-) mice by histological analysis. We also examined the proliferative index in archival nephrectomy tissue obtained from patients with ADPKD and normal controls. RESULTS: The proliferative index of non-cystic tubules in Pkd2 mutant mice as assessed by proliferating cell nuclear antigen and Ki67-positive nuclei was between 1-2%, values 5-10 times higher than control tissue. Similarly, the proliferative index of non-cystic tubules in human ADPKD kidneys was 40 times higher than corresponding controls. In Pkd2 mutant mice, significant correlations were found between the fibrosis score and the mean cyst area as well as with the proliferative index. Of significance, proliferating tubular cells were uniformly positive for polycystin-2 expression in Pkd2(+/-) kidney. CONCLUSION: These results suggest that an increase in cell proliferation is an early event preceding cyst formation and can result from haploinsufficiency at Pkd2. The possible pathogenic link between tubular cell proliferation, interstitial fibrosis and cyst formation is discussed.  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