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   2499篇
  免费   116篇
  国内免费   16篇
耳鼻咽喉   8篇
儿科学   52篇
妇产科学   92篇
基础医学   349篇
口腔科学   36篇
临床医学   169篇
内科学   408篇
皮肤病学   28篇
神经病学   334篇
特种医学   52篇
外科学   336篇
综合类   5篇
预防医学   344篇
眼科学   27篇
药学   225篇
中国医学   2篇
肿瘤学   164篇
  2021年   48篇
  2020年   14篇
  2019年   29篇
  2018年   48篇
  2017年   41篇
  2016年   48篇
  2015年   51篇
  2014年   72篇
  2013年   80篇
  2012年   161篇
  2011年   167篇
  2010年   89篇
  2009年   73篇
  2008年   136篇
  2007年   165篇
  2006年   153篇
  2005年   170篇
  2004年   155篇
  2003年   140篇
  2002年   139篇
  2001年   36篇
  2000年   36篇
  1999年   27篇
  1998年   25篇
  1997年   21篇
  1996年   11篇
  1993年   9篇
  1992年   24篇
  1991年   25篇
  1990年   20篇
  1989年   14篇
  1988年   20篇
  1987年   23篇
  1986年   19篇
  1985年   24篇
  1984年   12篇
  1983年   14篇
  1982年   11篇
  1979年   24篇
  1978年   17篇
  1977年   9篇
  1976年   15篇
  1975年   22篇
  1974年   18篇
  1973年   20篇
  1972年   11篇
  1969年   10篇
  1968年   11篇
  1932年   9篇
  1931年   12篇
排序方式: 共有2631条查询结果,搜索用时 15 毫秒
91.
Authors trace an ochronotic Hungarian family, which moved from Slovakia to Hungary 300 years ago. As the family members lived in a relatively close village community the gene mutation had been survived silently for ages before the clinical symptoms developed. Family tree analysis could detect with the use of allele specific PCR amplification–the p.G161R mutation of the homogentisic acid 1,2-dioxygenase (HGD) gene, which resulted in a specific genotype appearing in the Slovak population. We found a heterozygote member of this family who has children with an alkaptonuria-homozygote and known–heterozygote genotypes so there would be a high risk of alkaptonuria in their offsprings. Therefore genetic counselling is highly recommended to minimize the risk factors.  相似文献   
92.
Supercritical carbon dioxide (CO2) possesses germicide (bactericide and sporicide) effect. Despite of the fact, that this effect is used in industrial sterilization processes, the sterilization mechanism at molecular level is unclear. Our hypotheses can provide a molecular-biological explanation for the phenomenon.  相似文献   
93.
The amount of biogenic amines (dopamine and serotonin) and their metabolites (DOPAC, HVA, 5-HIAA, and 5-HTOL) in five regions of the brain (frontal cortex, hypothalamus, hippocampus, striatum, and brainstem) was studied in the male and female offspring of control and perinatally (48 h before birth or 48 h after birth) food and water deprived dams, when they were three months old, by using HPLC-EC determination. The increase of amine or metabolite level was dominant (19 values increased and 10 decreased related to control). Before-birth stress caused increase in 9 case and only 2 decreased, while in the case of after-birth stress 10 increased and 8 decreased. However, though there is no possibility to decide an exact tendency of direction, the after-birth stress (transmitted by milk) has more expressed effect. Striatum and brainstem were the most touched regions. There was a gender dependence with the dominance of males, except striatum. Blood plasma nociceptin level was also studied and there was a significant elevation in males after pre- and postnatal deprivation, while in females only after postnatal deprivation. The importance of the results in correlation with other stress effects is discussed.  相似文献   
94.
Summary Serum levels of beta lactoglobulin homologue placental protein 14 (PP14) were measured by a sensitive radioimmunoassay in various trophoblastic diseases and non-trophoblastic gynecologic malignancies. While trace amounts of protein were detected in sera of non-pregnant subjects (22.3±13.7 g/l), during first half of normal pregnancy a dramatic rise of serum-PP14 levels was demonstrable with a peak-value at 7th–10th week of gestation, followed by a decline thereafter. Serial determinations of PP14 have been performed in 31 patients with trophoblastic tumour (20 hydatidiform moles, 4 invasive moles and 7 choriocarcinomas). In patients with hydatidiform moles and invasive moles (273.5±106.5g/l and 162.2±109.6g/l) respective values before therapy were much exceeding the nonpregnant controls. After therapy there was a rapid decline of the serum-PP14 levels within two weeks. In patients with choriocarcinoma the PP14 values were moderately elevated (66.4±25.7g/l), and declined following the remission of disease. In 32 gynecological tumours (21 carcinomas of the cervix, 4 endometrial carcinomas, 5 ovarian carcinomas, 2 carcinomas of the vulva) the pretreatment levels were not different to normal controls.  相似文献   
95.
PP12 is one of the recently discovered soluble tissue antigens of the placenta. During normal pregnancy maternal serum PP12 levels rise during the first 18 weeks reaching a mean peak value of 139.9 +/- 40.26 micrograms/l; after that there is a fall to a mean value of 111.9 +/- 42.39 micrograms/l between 28 and 40 weeks. Significantly higher mean serum PP12 levels were found in the third trimester in two high risk pregnancy groups (281.09 +/- 117.08 micrograms/l in pre-eclamptic toxaemia and 203.71 +/- 73.77 micrograms/l in diabetes) while serum PP12 levels remained normal (114.94 +/- 58.06 micrograms/l) in twin pregnancy. The increase of serum PP12 concentration in toxaemia and in diabetes may be of considerable diagnostic significance.  相似文献   
96.
The authors report on the stage distribution and 5-years survival rate of 1158 cervical cancer cases treated from 1970 to 1980 at their center. Comparing these data to those of other institutions according to the 17th volume of Annual Report on the results of treatment in gynecological cancer they found that the stage distribution of their cases is not so favourable as that of other institutions. This unfavourable stage distribution is the consequence of the insufficiency of the mass screening of cervical cancer. Their treatment results characterized by the five year survival rate correspond to the international average.  相似文献   
97.
PURPOSE: To compare the results, complications, efficiency, and safety of simultaneous bilateral percutaneous nephrolithotomy (SBPN) and unilateral percutaneous nephrolithotomy (PCNL). PATIENTS AND METHODS: We compared the results and complications of 150 SBPNs with those of 300 unilateral PCNLs. All the procedures were performed by one surgeon which provides relatively constant parameters. The success rates, preoperative and postoperative laboratory results, and complications were compared on the basis of stone size and the number of nephrostomy tracks. RESULTS: There were no significant differences between the results and complications of SBPN and PCNL. The SBPN itself did not cause more blood loss than unilateral PCNL. In both groups, the blood loss was in direct proportion to the size of the stones and the number of nephrostomy tracks. After SBPN, kidney function improved >20% in 12.2% of the patients and worsened for more than 3 days in only 4%. Temporary worsening of kidney function occurred in the unilateral procedure group as well (8%), mostly in cases of solitary kidneys or bilateral stones. The SBPN was not more hazardous than unilateral PCNL (complication rate 11.3% v 14.3%, respectively). In both groups, most of the complications were in proportion to the size and difficulties of the stones. CONCLUSION: Simultaneous bilateral percutaneous nephrolithotomy is a safe and advantageous procedure that is not more hazardous than the separate PCNL in cases of bilateral large stone burdens. To our knowledge, these are the largest reported series of these procedures and the only comparative analysis of SBPN and PCNL.  相似文献   
98.
99.
The success of cortical resection for intractable epilepsy of neocortical origin is highly dependent on the accurate presurgical delineation of the regions responsible for generating seizures. In addition to EEG and structural imaging studies, functional neuroimaging such as positron emission tomography (PET) can assist lateralization and localization of epileptogenic cortical areas. In the presented studies, objectively delineated focal PET abnormalities have been analyzed in patients (mostly children) with intractable epilepsy, using two different tracers: 2-deoxy-2-[18F]fluoro-D-glucose (FDG), that measures regional brain glucose metabolism, and [11C]flumazenil (FMZ), that binds to GABAA receptors. The PET abnormalities were correlated with scalp and intracranial EEG findings, structural brain abnormalities, as well as surgical outcome data. In patients with extratemporal foci and no lesion on MRI, FMZ PET was more sensitive than FDG PET for identification of the seizure onset zone defined by intracranial EEG monitoring. In contrast, seizures commonly originated from the border of hypometabolic cortex detected by FDG PET suggesting that such areas are most likely epileptogenic, and should be addressed if subdural EEG is applied to delineate epileptic cortex. In patients with cortical lesions, perilesional cortex with decreased FMZ binding was significantly smaller than corresponding areas of glucose hypometabolism, and correlated well with spiking cortex. Extent of perilesional hypometabolism, on the other hand, showed a correlation with the life-time number of seizures suggesting a seizure-related progression of brain dysfunction. FMZ PET proved to be also very sensitive for detection of dual pathology (coexistence of an epileptogenic cortical lesion and hippocampal sclerosis). This has a major clinical importance since resection of both the cortical lesion and the atrophic hippocampus is required to achieve optimal surgical results. Finally, the author demonstrated that in patients with neocortical epilepsy, FDG PET abnormalities correctly regionalize the epileptogenic area, but their size is not related to the extent of epileptogenic tissue to be removed. In contrast, complete resection of cortex with decreased FMZ binding predicts good surgical outcome suggesting that application of FMZ PET can improve surgical results in selected patients with intractable epilepsy of neocortical origin.  相似文献   
100.
Investigating the scintigraphic images of jaws may have a diagnostic value of bone alterations of dental origin. Anterior view of whole body bone scintigraphy revealed hot spot on jaws of 61% (279) of patients. Twenty-six patients (mean age 58.3 year) from all of those who had increased tracer uptake (ITU) in the maxillo-mandibular region were called back for dental examination. 279 out of 459 (61%) patients had ITU in the maxillo-mandibular region. Dental examination revealed the dental origin of ITU in all cases. In case of periapical pathosis tracer uptake showed 28.79% increase compared to the contralateral side. In marginal periodontitis 23.82% ITU was found. In case of loading due to prosthesis 13.06% ITU was observed. The mean DMF-T value was 26.36 +/- 4.52 (D = 4.12, M = 20.8, F = 1.44). The prosthetic index was 0.42 on the mandible. The above mentioned data mean very low oral health conditions of the patients included in this examination. The results show that bone scintigraphy is a valuable procedure in detecting tooth related jaw lesions. Bone scintigraphy provides very useful data on oral health of these patients. Enrolling of these patients into regular dental care is inevitable.  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