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   268篇
  免费   2篇
儿科学   11篇
基础医学   91篇
口腔科学   6篇
临床医学   19篇
内科学   20篇
皮肤病学   4篇
神经病学   27篇
特种医学   12篇
外科学   16篇
综合类   3篇
预防医学   24篇
眼科学   2篇
药学   29篇
肿瘤学   6篇
  2021年   3篇
  2020年   3篇
  2019年   4篇
  2018年   3篇
  2017年   2篇
  2016年   4篇
  2015年   2篇
  2014年   3篇
  2013年   3篇
  2012年   6篇
  2011年   9篇
  2010年   11篇
  2009年   4篇
  2008年   9篇
  2007年   11篇
  2006年   10篇
  2005年   9篇
  2004年   8篇
  2003年   13篇
  2002年   10篇
  2001年   9篇
  2000年   9篇
  1999年   9篇
  1998年   11篇
  1997年   2篇
  1995年   4篇
  1994年   3篇
  1993年   2篇
  1992年   4篇
  1991年   5篇
  1990年   4篇
  1989年   12篇
  1987年   4篇
  1986年   7篇
  1985年   6篇
  1979年   2篇
  1978年   3篇
  1977年   3篇
  1976年   6篇
  1975年   5篇
  1974年   6篇
  1973年   4篇
  1972年   4篇
  1969年   2篇
  1968年   3篇
  1967年   2篇
  1966年   3篇
  1965年   1篇
  1941年   1篇
  1936年   1篇
排序方式: 共有270条查询结果,搜索用时 15 毫秒
261.
To predict a potential value of a viral ID50 for a macro-organism of interest (e.g. humans), it is necessary to determine in vitro two parameters of the interaction of the virus with susceptible cells of the host, i.e. the probability of the virus' productive absorption on a susceptible cell and the average virus yield per cell. A different macroorganism (a model animal) and primary cells obtained from it can be used to determine the value of a scale factor, which accounts for the difference between the values of the probability of the virus' absorption measured in vivo and in vitro. An original mathematical model is used to convert the above-mentioned data to ID50 for the macroorganism of interest. It was shown that the method of cultivating influenza virus (A/ Aichi/2/68) in primary suspension culture of respiratory tract cells of rats and two breeds of mice may be used to estimate potential human susceptibility to novel influenza viruses. This work was sponsored by DAPRA, USA, and performed under the contract 450p to the International Science and Technology Center, Moscow.  相似文献   
262.
Antisense strategy was used to investigate the role of alpha2A-adrenoceptor (alpha2A-AR) subtype in anxiety-related behavior. A 18-mer phosphorothioate oligodeoxynucleotide (AS-ODN) complementary to the alpha2A-AR mRNA was administered to the adult male rats for 3 days (1 nmol/5 microl/day) into the region of locus coeruleus (LC). Control groups received infusions of either oligodeoxynucleotide of a random sequence (RS-ODN) or saline. Treatment with AS-ODN significantly reduced the levels of alpha2A-AR mRNA in the brain stem. At the same time, AS-ODN treatment caused only a small reduction in [(3)H]clonidine binding (by 26-32%) in the brain stem which was not significant. Compared to both RS-ODN and saline controls, treatment with AS-ODN significantly increased the percentage of open arm entries in the elevated plus-maze while the total number of arm entries was unaltered. Also, AS-ODN treatment elevated basal levels of plasma corticosterone by 217% and 96% compared to both RS-ODN and saline controls. These changes in the hormone concentrations were at a level of marginal significance (p<0.1 versus random group). Taken together, the data indicate that administration of AS-ODN against alpha2A-ARs in the LC significantly reduced expression of alpha2A-AR mRNA in brain stem, moderately increased plasma corticosterone and had anxiolytic-like effect in the elevated plus-maze.  相似文献   
263.
In spite of rare incidence, cystic intracranial meningiomas deserve interest due to difficulties in correct preoperative diagnosis. Authors present a case report of a patient with cystic meningioma mimicking astrocytoma. In addition, review of literature is performed.  相似文献   
264.

Objectives

The aim of the study was to determine total and unbound lopinavir (LPV) plasma concentrations in HIV‐infected pregnant women receiving lopinavir/ritonavir (LPV/r tablet) undergoing therapeutic drug monitoring (TDM) during pregnancy and postpartum.

Methods

Women were enrolled in the study who were receiving the LPV/r tablet as part of their routine prenatal care. Demographic and clinical data were collected and LPV plasma (total) and ultrafiltrate (unbound) concentrations were determined in the first, second and third trimesters using high‐performance liquid chromatography–tandem mass spectrometry (HPLC‐MS/MS). Postpartum sampling was performed where applicable. Antepartum and postpartum trough concentrations (Ctrough) were compared independently [using analysis of variance (anova )] and on a longitudinal basis (using a paired t‐test).

Results

Forty‐six women were enrolled in the study (38 Black African). Forty women initiated LPV/r treatment in pregnancy. Median (range) gestation at initiation was 25 (15–36) weeks and median (range) baseline CD4 count and viral load were 346 (14–836) cells/μL and 8724 (<50–267408) HIV‐1 RNA copies/mL, respectively. Forty women (87%) had LPV concentrations above the accepted minimum effective concentration for wild‐type virus (MEC; 1000 ng/mL). Geometric mean (95% confidence interval [CI]) total LPV concentrations in the first/second [3525 (2823–4227) ng/mL; n=16] and third [3346 (2813–3880) ng/mL; n=43] trimesters were significantly lower relative to postpartum [5136 (3693–6579) ng/mL; n=12] (P=0.006). In a paired analysis (n=12), LPV concentrations were reduced in the third trimester [3657 (2851–4463) ng/mL] vs. postpartum (P=0.021). No significant differences were observed in the LPV fraction unbound (fu%). Conclusions The above target concentrations achieved in the majority of women and similarities in the fu% suggest standard dosing of the LPV/r tablet is appropriate during pregnancy. However, reduced LPV concentrations in the second/third trimesters and potentially compromised adherence highlight the need for TDM‐guided dose adjustment in certain cases.  相似文献   
265.
Rare clinical observation of a patient with spontaneous rupture of posterior lateral choroid artery aneurysm is described. The patient was surgically treated--clipping of aneurismal neck with preservation of arterial lumen was performed. The authors illustrated the paper with angiographic data and morphological view confirming genuine structure of aneurysm.  相似文献   
266.
The aim of this study was to investigate structure of cerebral arteriovenous malformations (AVM). We examined and treated 5 patients with AVMs of cerebral hemispheres. Treatment consisted of endovascular embolization with subsequent surgical resection of AVM. The series included 3 female and 2 male patients (age 19-44, mean - 28 years). Histoacryl (B. Braun, Germany) was used for embolization. Corrosion specimens were prepared according to standard technique and examined using optic and scanning electron microscopy. AVMs had similar structure. Casts were formed by distal segments of afferent arteries, fistulas, interjacent venous vessels, proximal segments of draining veins and vessels of angiomatous surrounding. The latter consisted of abnormal network of small arteries, veins, fistulas and dilated capillaries. The most variable length and formation of glomeruli was characteristic for interjacent venous vessels. AVMs extensively anastomosed with cerebral vessels. Big amount of aneurysms and aneurysmatic bulgings was present. Aneurysms of intranidal segment of afferent artery and angiomatous vessels are demonstrated.  相似文献   
267.
Hunteria umbellata (K. Schum.) Hallier f. (family: Apocynaceae) is reputed for the folkloric management of labour, pain and swellings, stomach ulcers, diabetes, obesity, and anaemia, with no scientific report of its toxicity and reversibility profile. The present study was, therefore, aimed at investigating the in vivo toxicity and reversibility profile of the aqueous seed extract of Hunteria umbellata (HU). The acute oral and intraperitoneal toxicity studies of HU were determined in Swiss albino mice while its 90-day oral toxicity and toxicity reversibility profile on anthropometric, biochemical, haematological and histopathological parameters were also assessed using standard procedures. Results showed that the LD50 values for the acute oral and intraperitoneal toxicity studies for HU were estimated to be 1000 mg/kg and 459.3 mg/kg, respectively. Visible signs of immediate and delayed toxicities including starry hair coat, respiratory distress, and dyskinesia were observed. For the chronic oral toxicity study, HU administered for 90 days produced significant (p<0.001) reductions in the weight gain pattern and significant (p<0.001) and dose related increases in the relative weights of liver, stomach, spleen, testis, lungs and heart, at the 100 and 500 mg/kg of HU. Chronic HU treatment also produced significant (p<0.05, p<0.001) dose related reductions in the serum levels of fasting blood glucose, bicarbonate, urea and creatinine while causing non-significant (p>0.05) alterations in the serum levels of sodium, potassium, alaninine transaminase, aspartate transaminase, alkaline phosphatase, total and conjugated bilirubin, total protein and albumin. Also, chronic oral treatment with HU produced significant (p<0.05, p<0.01, p<0.001) and dose-related increases in the red cell count, packed cell volume, haemoglobin concentration, platelet count, total leucocyte count and lymphocyte differential while producing significant (p<0.05) reductions in neutrophil and granulocyte differentials. HU also produced histological features of proliferations of the stomach epithelia, lung tissues, splenic white and red pulps, and testicular spermatogenic series. Following 14 days of oral toxicity reversibility test, there was no significant (p>0.05) reversal in the serum levels of the biochemical and haematological parameters investigated, including the HU-induced histological lesions.Overall, results of this study showed that HU has a relatively low oral toxicity profile but its prolonged use, particularly, at high doses should be with great caution.Key words: Hunteria umbellata, Toxicity and reversibility profile, Haematology, Liver and Renal function tests, Histopathology, Rodents  相似文献   
268.
The effects of long-term administration of boiled aqueous extract of Syzigium aromaticum (SYZ), commonly known as clove (which has been locally employed for treating gastrointestinal tract diseases and also used as food spices), on some biochemical indices, such as body weight, liver functions and blood parameters were studied in adult albino rats of both sexes. Selected doses of 300 and 700 mg kg−1 were given orally through cannular to groups of animals for a period of 90 days, while the control group received distilled water throughout the duration of study via the same route. Blood samples collected after therapy and assayed for activities of some liver enzymes recorded a significant (p<0.05) and prominent effect on ALP and AST. Measurement of haematological parameters also revealed significant effects (p<0.05; p<0.001) on Hb, RBC (p<0.05), PCV (p<0.001), platelets (p<0.001) and granulocytes (p<0.001). An insignificant reduction was recorded for total WBC. The histopathological study conducted was in consonance with the results of the biochemical investigations that the aqueous extract of SYZ even at moderate doses, significantly affects body organs, their enzymes as well as the various functions. LD50 for both intraperitoneal and oral routes of SYZ were 263 and 2500 mg kg−1 respectively. The present work has revealed the toxicity of sub chronic administration of SYZ, which suggests that its prolonged usage must be avoided.  相似文献   
269.
Pilocytic astrocytoma (PA) is a low-grade glial tumor (WHO grade I) with predominant occurrence in pediatric patients. According to many authors, stereotactic radiosurgery (SRS) and radiotherapy (SRT) promote long-term remission or retardation of tumor progression in patients with in inoperable lesions after incomplete resection or recurrence. Therefore it is essential to determine the role of SRS and SRT in complex management of patients with deep-seated PA. Since April 2005 till May 2010 101 patient with intracranial PA was treated in department for radiation therapy of Burdenko Neurosurgical Institute. The series consisted of 70 pediatric patients (below 17 years inclusively) and 31 adults, of them--51 male and 50 female patients. Mean age was 15.1 years (9.8 years in children and 28.7 in adults). In 90 patients (89.2%) tumors were previously histologically verified (tumor resection in 83 cases and biopsy in 7). In 11 (10.8%) patients diagnosis of PA was based on clinical and neurovisualization data. In most cases SRT (66 (66.3%) patients) was preformed, the rest 35 (34.7%) patients were treated by SRS. Median follow-up from the onset of disease reached 52 months (2-228 months). Catamnestic data were available in 88 (87%) patients. By the end of catamnestic follow-up (December 2010) 87 (98.8%) patients treated by SRS and SRT were alive. Median follow-up from the start of radiation treatment was 22.7 months (6-60 months). Progression of tumor was observed in 20 patients (22.7%), in 18 of them due to cyst growth. 18 patients were reoperated. In 12 operated patients histological examination and its comparative analysis were performed. We found that alterations in the tumor tissue, accompanied by regression of solid component and progression of cystic portion, represent reactive-degenerative changes in the tumor as a consequence of radiation-induced pathomorphism. SRS and STR are effective techniques for treatment of patients with primary and recurrent PA despite regardless of localization of the tumor. There procedures should be performed shortly after non-radical resection. Control of tumor growth by the present time (median follow-up is 22.7 months) reaches 98%. "Progression" of the tumor due to enlargement of cystic portion shortly after SRT and SRS represents reactive-degenerative alterations in the tumor tissue and should not be evaluated as true recurrence; without neurological deterioration these cases do not require special treatment.  相似文献   
270.
MDCK and Vero (B) cell cultures were propagated during 10 passages in the experimental nutrient media containing the soybean powder hydrolyzate prepared using trypsin and bromelain enzymes and the rice powder hydrolysate prepared with trypsin and in the control DMEM and SFM4 MegaVir media. The karyological, morphological, and proliferative characteristics of continuous cultures were examined and compared. The experimental media supplied with 3% fetal bovine serum (FBS) (Gibco, U.S.A.) showed high growth-enhancing properties and failed to affect their morphology. After propagated during 10 passages in the experimental media preserved a stable karyotype. MDCK cell cultures in the nutrient media based on rice and soybean powder hydrolyzates low (2%) in FBS caused no substantial changes in the proliferation indices and morphological and karyological characteristics of cell cultures.  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