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   2273篇
  免费   88篇
  国内免费   10篇
耳鼻咽喉   8篇
儿科学   189篇
妇产科学   73篇
基础医学   341篇
口腔科学   42篇
临床医学   190篇
内科学   477篇
皮肤病学   30篇
神经病学   139篇
特种医学   52篇
外科学   165篇
综合类   72篇
一般理论   3篇
预防医学   154篇
眼科学   42篇
药学   221篇
  1篇
中国医学   28篇
肿瘤学   144篇
  2023年   9篇
  2022年   37篇
  2021年   59篇
  2020年   39篇
  2019年   53篇
  2018年   84篇
  2017年   43篇
  2016年   70篇
  2015年   52篇
  2014年   72篇
  2013年   109篇
  2012年   167篇
  2011年   157篇
  2010年   90篇
  2009年   51篇
  2008年   135篇
  2007年   126篇
  2006年   109篇
  2005年   110篇
  2004年   106篇
  2003年   99篇
  2002年   78篇
  2001年   46篇
  2000年   59篇
  1999年   35篇
  1998年   13篇
  1997年   12篇
  1996年   8篇
  1995年   8篇
  1994年   11篇
  1993年   10篇
  1992年   24篇
  1991年   18篇
  1990年   20篇
  1989年   18篇
  1988年   9篇
  1987年   18篇
  1986年   19篇
  1985年   16篇
  1984年   15篇
  1983年   9篇
  1979年   8篇
  1977年   10篇
  1976年   11篇
  1974年   10篇
  1973年   13篇
  1972年   10篇
  1971年   8篇
  1970年   12篇
  1969年   13篇
排序方式: 共有2371条查询结果,搜索用时 31 毫秒
81.
82.
Molecular characterization of β-thalassemia (β-thal) is essential in prevention and in understanding the biology of the disease. Deletion mutations are relatively uncommon in β-thal. In this report, we describe a novel 26 bp deletion from codon 6 to codon 14 in the β-globin in a consanguineous family from Tamil Nadu, India. This novel mutation causes a shift in the normal reading frame of the β-globin coding sequence, and consequently, a premature chain termination of translation due to the creation of a stop codon at the position of codon 21. The identification of this novel deletional mutation adds to the repertoire of β-thal mutations in India.  相似文献   
83.
84.
85.
Studies on influence of lipid lowering therapies have generated wide controversial results on the role of cholesterol on memory function. However recent studies revealed that cholesterol lowering treatment substantially reduce the risk of dementia. The objectives of this study were to analyze the effect of statins on memory function and to establish the relationship between increase/decrease in cholesterol synthesis, total cholesterol level and memory function in animals. We examined the relationship between biosynthesis of cholesterol and memory function using two statins (lipophilic simvastatin and hydrophilic pravastatin) and high cholesterol diet in mice for 15?days and 4?months. Memory performance was evaluated with two different behavioral tests and various biochemical parameters such as serum cholesterol, whole brain cholesterol, brain 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) activity and brain acetylcholine esterase (AChE) activity. We found that statin treatment for 4?months, but not for 15?days, showed significant improvement in memory function whereas high cholesterol diet showed significant impairment of memory. However long-term statin treatment showed significant decrease in serum cholesterol level as well as brain AChE level. Moreover high cholesterol diet showed significant decrease in memory function with an increase in serum cholesterol level as well as brain AChE level. There is no direct correlation between brain cholesterol level, as well as HMG-CoA activity with memory function regulation. However there is definite link between plasma cholesterol level and AChE level. A long-standing plasma cholesterol alteration may be essential to regulate memory function which in turn might be mediated through AChE modulated pathway.  相似文献   
86.
Silk fibroin (SF) is well known for its excellent biocompatible properties facilitating its application in the field of biomedical engineering through different biomaterial fabrications in the recent era. Here in this study, novel nanoparticles from non-mulberry SF of Antheraea assamensis were fabricated, characterized and evaluated for its applicability as nanocarrier. Fabricated nanoparticles were initially compared with prevailing SF nanoparticles from Bombyx mori. Fabricated A. assamensis silk fibroin nanoparticles (AA-SFNps) were found to be lesser in size (80–300 nm in diameter) than B. mori silk fibroin nanoparticles (BM-SFNps) (120–500 nm in diameter). When checked for stability, AA-SFNps were found to be more stable than BM-SFNps in biological media. FTIR and XRD studies revealed persistence of structural properties even after fabrication. TGA and DSC studies showed AA-SFNps to be thermally more stable than BM-SFNps without any cytotoxicity (MTT assay). On loading with model drug Doxorubicin hydrochloride (DOX), AA-SFNps exhibited an encapsulation efficiency of 94.47% with 11.81% loading of the anticancer drug. Cumulative release study revealed highest percentage release of DOX (42.1 ± 0.4%) at pH 5.2 on day 7 in comparison to pH 7.4 and 8.0. Sustained release profile of the DOX loaded AA-SFNps (AA-SFNps-DOX) was clearly reflected and it was found to be highly cytotoxic against triple negative MDA-MB-231 cells in comparison to free DOX at different time points. Overall, this study showed the efficacy of the AA-SFNps as a nanocarrier for future drug delivery applications.

Novel Antheraea assamensis silk fibroin nanoparticles (AA-SFNps) exhibiting enhanced activity as doxorubicin hydrochloride (DOX) loaded nanocarriers for future drug delivery applications.  相似文献   
87.

Introduction and hypothesis

Polyacrylamide hydrogel (PAHG, Bulkamid®) is one of several injectable agents currently used for the treatment of women with urinary stress incontinence. Although bulking agents appear to have lower efficacy rates compared to other surgical treatments, current evidence based on large prospective or comparative studies as well as systematic reviews is limited. The purpose of this study was to conduct a systematic review on the efficacy of PAHG in the treatment of female patients with stress urinary incontinence with regard to reproducibility, feasibility, safety and clinical outcome.

Methods

We searched MEDLINE (1966–2015), Scopus (2004–2015), POPLINE (1974–2015) and ClinicalTrials.gov (2008–2015) along with reference lists of electronically retrieved studies. Observational studies, prospective, retrospective and randomized controlled studies were included. Two reviewers independently selected studies, assessed the risk of bias and tabulated data to structured forms.

Results

We included 8 studies, which enrolled a total of 767 patients who received treatment with PAHG. We found that 186 of 767 women (24.3 %, range 12–35 %) required reinjection in order to achieve adequate efficacy. The most frequent adverse effects were pain at the site of injection (4–14 %) and urinary tract infections (3–7 %). Both the number of incontinence episodes/24 h and the number of ml/24 h were significantly reduced 1 year following treatment and the quality of life of patients was significantly improved.

Conclusions

PAHG is a safe intervention for treating women with stress urinary incontinence, but repeat injections are often required. Further research is mandated in the field in order to compare its efficacy to other bulking agents.
  相似文献   
88.
Fertility preservation is an area of immense interest in today's society. The most effective and established means of fertility preservation is cryopreservation of gametes (sperm and oocytes) and embryos. Gonadal cryopreservation is yet another means for fertility preservation, especially if the gonadal function is threatened by premature menopause, gonadotoxic cancer treatment, surgical castration, or diseases. It can also aid in the preservation of germplasm of animals that die before attaining sexual maturity. This is especially of significance for valuable, rare, and endangered animals whose population is affected by high neonatal/juvenile mortality because of diseases, poor management practices, or inbreeding depression. Establishing genome resource banks to conserve the genetic status of wild animals will provide a critical interface between ex-situ and in-situ conservation strategies. Cryopreservation of gonads effectively lengthens the genetic lifespan of individuals in a breeding program even after their death and contributes towards germplasm conservation of prized animals. Although the studies on domestic animals are quite promising, there are limitations for developing cryopreservation strategies in wild animals. In this review, we discuss different options for gonadal tissue cryopreservation with respect to humans and to laboratory, domestic, and wild animals. This review also covers recent developments in gonadal tissue cryopreservation and transplantation, providing a systematic view and the advances in the field with the possibility for its application in fertility preservation and for the conservation of germplasm in domestic and wild species.  相似文献   
89.
Penicillium marneffei (PM), the only dimorphic species of the genus penicillium is the etiological agent of penicilliosis marneffei. This opportunistic fungal infection occurs among human immunodeficiency virus (HIV) infected and other immunocompromised patient in several regions of South-east Asia, where the infection is considered as an indicator disease of AIDS. A case of penicilliosis marneffei is reported in a patient whose HIV status was unknown and later turned to be in the late stage of AIDS. This demonstrates that it is indeed an indicator disease of AIDS. In India, penicilliosis has been reported among the inhabitants of Manipur state where the prevalence of HIV infection / AIDS is very high. The causative agent was first isolated from a captive bamboo rat. Investigation of the prevalence of the organism among bamboo rats of different countries of South East Asia revealed four species of bamboo rats to be harboring the organism. These four species of bamboo rats are Rhizomys sinensis, R. pruinosus, R. sumatrensis and Cannomys badius. In Manipur, Penicillium marneffei has been isolated from Cannomys badius. Any patient presenting with penicilliosis marneffei should be subjected to HIV counselling and testing if the HIV status is not known and further study regarding the ecology and epidemiology of the fungus is needed.  相似文献   
90.
Syringomatous adenoma of the nipple is a rarely encountered neoplasm of the breast with histological features similar to eccrine syringoma of the skin. This tumour which is locally invasive with high potential for recurrence if incompletely excised is considered benign and a complete excision is sufficient. Hence it deserves recognition by pathologists and surgeons for appropriate management. We report a case of syringomatous adenoma of the nipple in a postmenopausal diabetic woman who was incidentally found to have a subareolar mass in her right breast. Clinical examination and mammographic findings indicated malignancy. Histopathological examination showed features of syringomatous adenoma of the nipple. A clinicopathological study and histological differential diagnosis of this unusual tumour is described.  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