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   47146篇
  免费   2656篇
  国内免费   346篇
耳鼻咽喉   535篇
儿科学   1488篇
妇产科学   1231篇
基础医学   4864篇
口腔科学   1465篇
临床医学   3963篇
内科学   10212篇
皮肤病学   900篇
神经病学   3090篇
特种医学   1868篇
外国民族医学   5篇
外科学   7990篇
综合类   912篇
现状与发展   3篇
一般理论   29篇
预防医学   3759篇
眼科学   1605篇
药学   3642篇
  1篇
中国医学   286篇
肿瘤学   2300篇
  2023年   380篇
  2022年   998篇
  2021年   1686篇
  2020年   1020篇
  2019年   1318篇
  2018年   1679篇
  2017年   1198篇
  2016年   1321篇
  2015年   1448篇
  2014年   1801篇
  2013年   2239篇
  2012年   3735篇
  2011年   3771篇
  2010年   1950篇
  2009年   1661篇
  2008年   2951篇
  2007年   3140篇
  2006年   2814篇
  2005年   2648篇
  2004年   2409篇
  2003年   2071篇
  2002年   1827篇
  2001年   881篇
  2000年   909篇
  1999年   565篇
  1998年   331篇
  1997年   252篇
  1996年   276篇
  1995年   185篇
  1994年   167篇
  1993年   158篇
  1992年   179篇
  1991年   206篇
  1990年   165篇
  1989年   182篇
  1988年   161篇
  1987年   152篇
  1986年   121篇
  1985年   167篇
  1984年   102篇
  1983年   78篇
  1982年   86篇
  1981年   79篇
  1980年   75篇
  1979年   61篇
  1978年   53篇
  1977年   57篇
  1976年   61篇
  1975年   52篇
  1974年   44篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Exposure of male albino rats to DDVP insecticide at sublethal dose of 30 mg/kg/day through dermal painting for a period of 90 days didn't show any intoxication symptoms or mortality. However, cytopathological changes in testicular and liver tissues were evident. There was a positive correlation between the degree of cellular damage and the period of insecticide administration. In general, damages were prominent in rats treated for 30 days or more. Histological examination of testes showed degenerative seminiferous tubules and fewer leydig cells. Hepatic cells were congested, atrophied and showed different stages of necrobiotic changes. This suggests a great care and caution for workers during different phases of DDVP insecticide handling.  相似文献   
102.
Bone scintigraphy in tuberculous sacroiliitis   总被引:1,自引:0,他引:1  
Radionuclide bone imaging is becoming increasingly important in the evaluation of musculoskeletal pain of uncertain cause. A case in which Tc-99m MDP bone imaging was employed to investigate complaints of low back pain is presented. Scan abnormalities directed clinicians towards appropriate further workup and diagnosis of unilateral tuberculous sacroiliitis.  相似文献   
103.
Thirty-five patients hospitalized for recent angiographically documented arterial occlusion in the legs (27 femoropopliteal arteries and eight grafts) benefited from local fibrinolytic therapy delivered at the site of the occlusion with a 4- or 5-F catheter. This therapy combined a continuous urokinase (UK) infusion of 1,000 U/kg/hour and a lysyl plasminogen (LYS-PLG) infusion of 15 microkatals every 30 minutes. Angiographically confirmed lysis was obtained in 85% of the cases. Only 3% of the patients had major and 6% had minor groin hematomas. Only two patients had concentrations of fibrinogen as low as 100 mg/dl. Intravascular infusion of UK-LYS-PLG is as effective as streptokinase. Its excellent tolerance makes it a good alternative in the treatment of acute ischemia in the lower limbs.  相似文献   
104.
BACKGROUND: The diagnosis of analgesic nephropathy has improved significantly with modern imaging techniques. We reviewed a large portion of the Hungarian dialysis population to obtain additional insight into the problem. METHODS: Twenty-two participating dialysis units enrolled 1400 patients on renal replacement therapy between 1 January 1995 and 1 January 1998. Patients with no known aetiology (n = 284) were interviewed and studied with renal imaging. We assessed the presence of decreased renal mass combined with either bumpy contours, papillary calcification, or both. The subjects studied were interrogated extensively. RESULTS: Our survey suggested analgesic nephropathy in 47 of 1400 patients (3.3%), 3-fold higher than the EDTA database estimate for Hungary. The analgesics most commonly abused were phenacetin-containing mixtures. The driving symptoms were mainly headache and joint pain. Cardiovascular complications were more common than in the rest of the dialysis population, independent of smoking and lipid values (P<0.01). CONCLUSIONS: Phenacetin should be banned. Our study results support the need for longitudinal cohort and case-control studies in Hungary.  相似文献   
105.
PURPOSE: To report on iodine-125 ((125)I) interstitial irradiation in the treatment of brain stem tumors. PATIENTS AND METHODS: Two patients with brain stem tumors were treated with CT- and image fusion-guided (125)I stereotactic brachytherapy. RESULTS: By March 2003, the patients had been followed up for 47 and 13 months, respectively. In case 1, the tumor volume was 1.98 cm(3) on the control CT, indicating a 65.5% shrinkage as compared to a target volume of 5.73 cm3 at the time of brachytherapy. In case 2, shrinkage was more distinct. After irradiation, the cyst volume was 0.16 cm(3) on the control MRI, indicating a 97.4% shrinkage as compared to a target volume of 6.05 cm(3) at the time of brachytherapy, i. e., the metastasis had virtually disappeared. CONCLUSION: CT- and image fusion-guided (125)I stereotactic brachytherapy can be performed during the biopsy session. The procedure can be well planned dosimetrically and is surgically precise.  相似文献   
106.
3,4-Methylenedioxymethamphetamine damages fine serotonergic fibers and nerve terminals in adult organisms. Developing animals seem to be less susceptible to this effect, possibly due to a lack of drug-induced hyperthermia. We tested this hypothesis by producing hyperthermia in neonatal rats for 2 h after each of twice-daily MDMA (10 mg/kg s.c.) or saline injections administered from postnatal days 1–4. Other drug-treated and control litters were maintained at normothermic temperatures following injection. Changes in forebrain serotonergic innervation were assessed at postnatal day 25 (serotonin transporter binding and serotonin levels), postnatal day 60 (serotonin transporter binding), and 9 months of age (serotonin transporter immunohistochemistry). We also determined the influence of MDMA treatment on apoptotic activity by means of immunohistochemistry for cleaved caspase-3 at postnatal day 5. The hippocampus showed significant MDMA-related reductions in serotonergic markers at postnatal day 25 and postnatal day 60. At 9 months, there was no effect of prior MDMA exposure on serotonin transporter-immunoreactive fiber density in the hippocampus; however, significant reductions in fiber density were observed in two neocortical areas and a hyperinnervation was found in the caudate-putamen and nucleus accumbens shell. MDMA treatment also produced a two-fold increase in the number of cleaved caspase-3-immunoreactive cells in the rostral forebrain and hippocampus. All of these effects were completely independent of pup body temperature. These findings demonstrate that neonatal MDMA administration exposure stimulates apoptotic cell death in various forebrain areas and also leads to a long-term reorganization of the forebrain serotonergic innervation. Consequently, offspring of MDMA-using women may be at heightened risk for abnormal neural and behavioral development.  相似文献   
107.
Hemoperitoneum secondary to rupture of cystic artery pseudoaneurysm   总被引:1,自引:0,他引:1  
BACKGROUND:Spontaneous hemoperitoneum of hepato- biliary origin is commonly due to hemorrhage from a liver tumor.It is rarely caused by spontaneous rupture of aneurysm in visceral arteries. METHODS:We report an unusual case of hemoperitoneum caused by rupture of cystic artery pseudoaneurysm,and also outline the approach to its management through surgical and radiological methods. RESULTS:In our patient,the pseudoanurysm was initially treated with percutaneous thrombin injection.However this method of treatment failed after initial success.The pseudoanurysm was finally obliterated successfully using microcoil embolization. CONCLUSIONS:The mainstay of treatment of cystic artery pseudoaneurysm is cholecystectomy and ligation of the aneurysm.Recent publications showed success in using microcoil embolisation.In this case we also outline the use of percutaneous thrombin injection as a definitive treatment method and discuss its success or failure as a new method of treatment.  相似文献   
108.
Inversion recovery (IR), commonly considered a pulse sequence capable of producing T1-weighted images with excellent display of normal anatomy, is versatile: The null point and peak time provide a useful, succinct summary of the properties of IR and its capacity for producing both T1- and T2-weighted images. Shortening of the inversion time (TI) and creation of a short-TI inversion-recovery (STIR) pulse sequence increases sensitivity to malignancy and other abnormalities by making the effects of prolonged T1 and T2 on signal intensity additive and by nulling the signal from fat. The authors examined over 300 patients with various malignancies and compared STIR images with T1- and T2-weighted images obtained at 0.5 T. In 43 cases, signal-difference-to-noise ratios (SD/Ns) were calculated between tumor, fat, and muscle. In general, STIR images demonstrated tumor as a conspicuously high-intensity area in a background of muted, discernible anatomic detail. The good contrast achieved with STIR sequences between tumor and fat (SD/N = 18.1) and tumor and muscle (SD/N = 12.9) consolidated into a single image the information contained separately on T1- and T2-weighted images, which facilitates efficient detection and localization of malignancy.  相似文献   
109.
Eleven patients with portal hypertension due to infection with Schistosoma mansoni underwent splenectomy and devascularization operations. The patients were examined with ultrasound once preoperatively and twice postoperatively over a period of about 6 months. Following surgery there was significant and sequential reduction in the diameter of the portal vein at the hilum and the splenic vein at the pancreas. The liver lengths and index of liver size did not change significantly. No changes in the degree of periportal fibrosis could be detected.  相似文献   
110.
Biodistribution of iodine-131-labeled Lipiodol Ultra-Fluide (I-131 LUF) injected into the hepatic artery was studied scintigraphically in 47 patients with hepatocellular carcinoma (n = 23), hepatic metastases (n = 14), or normal livers (n = 10). The investigation was extremely well tolerated. I-131 LUF concentrated mainly in the liver (L) and the lungs (l), with L/L + l activity ratios greater than 75% for all three groups of patients. I-131 LUF distribution was homogeneous in normal livers and heterogeneous in cirrhotic livers. I-131 LUF concentrated in the tumor with a tumorous (T) to nontumorous (NT) activity ratio (T/NT) of 4.3 +/- 3.6 for hepatocellular carcinoma and 2.4 +/- 0.7 for hepatic metastases. The effective half-life of I-131 LUF is more than 4.5 days for the three groups. It was eliminated mainly through the urine. Clearance from tumor is slower than from normal liver, as shown by the increase in T/NT at day 18. Biodistribution did not change in patients who had a second injection, which indicates that there is no saturation phenomenon. The results of this study suggest that LUF may be considered as a potential carrier vehicle for therapeutic agents.  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